Failed awake craniotomy: a retrospective analysis in 424 patients undergoing craniotomy for brain tumor.

PubMed

Nossek, Erez; Matot, Idit; Shahar, Tal; Barzilai, Ori; Rapoport, Yoni; Gonen, Tal; Sela, Gal; Korn, Akiva; Hayat, Daniel; Ram, Zvi

2013-02-01

Awake craniotomy for removal of intraaxial tumors within or adjacent to eloquent brain regions is a well-established procedure. However, awake craniotomy failures have not been well characterized. In the present study, the authors aimed to analyze and assess the incidence and causes for failed awake craniotomy. The database of awake craniotomies performed at Tel Aviv Medical Center between 2003 and 2010 was reviewed. Awake craniotomy was considered a failure if conversion to general anesthesia was required, or if adequate mapping or monitoring could not have been achieved. Of 488 patients undergoing awake craniotomy, 424 were identified as having complete medical, operative, and anesthesiology records. The awake craniotomies performed in 27 (6.4%) of these 424 patients were considered failures. The main causes of failure were lack of intraoperative communication with the patient (n = 18 [4.2%]) and/or intraoperative seizures (n = 9 [2.1%]). Preoperative mixed dysphasia (p < 0.001) and treatment with phenytoin (p = 0.0019) were related to failure due to lack of communication. History of seizures (p = 0.03) and treatment with multiple antiepileptic drugs (p = 0.0012) were found to be related to failure due to intraoperative seizures. Compared with the successful awake craniotomy group, a significantly lower rate of gross-total resection was achieved (83% vs 54%, p = 0.008), there was a higher incidence of short-term speech deterioration postoperatively (6.1% vs 23.5%, p = 0.0017) as well as at 3 months postoperatively (2.3% vs 15.4%, p = 0.0002), and the hospitalization period was longer (4.9 ± 6.2 days vs 8.0 ± 10.1 days, p < 0.001). Significantly more major complications occurred in the failure group (4 [14.8%] of 27) than in the successful group (16 [4%] of 397) (p = 0.037). Failures of awake craniotomy were associated with a lower incidence of gross-total resection and increased postoperative morbidity. The majority of awake craniotomy failures were preventable by adequate patient selection and avoiding side effects of drugs administered during surgery.

Trans-lamina terminalis approach to third ventricle using supraorbital craniotomy: technique description and literature review for outcome comparison with anterior, lateral and trans-sphenoidal corridors.

PubMed

Krishna, V; Blaker, B; Kosnik, L; Patel, S; Vandergrift, W

2011-10-01

The trans-lamina terminalis approach has been described to remove third ventricular tumors. Various surgical corridors for this approach include anterior (via bifrontal craniotomy), anterolateral (via supra-orbital craniotomy), lateral (via pterional craniotomy) and trans-sphenoidal corridors. Supra-orbital craniotomy offers a minimally invasive access for resection of third ventricular tumors. The trans-lamina terminalis technique through a supra-orbital craniotomy is described. Also, a literature review of clinical outcome data was performed for the comparison of different surgical corridors (anterior, antero-lateral, lateral, and trans-sphenoidal). The operative steps and anatomic landmarks for supra-orbital craniotomy are discussed, along with 3 representative cases and respective outcomes. Gross total resection was achieved in 2 patients, and one patient required reoperation for recurrence. Based on the current literature, the clinical outcomes after supra-orbital craniotomy for trans-lamina terminalis approach are comparable to other surgical corridors. The supra-orbital craniotomy for trans-lamina terminalis approach is a valid surgical choice for third ventricular tumors. The major strengths of this approach include minimal brain retraction and direct end-on view; however, the long working distance is a major limitation. The clinical outcomes are comparable to other surgical corridors. Sound understanding of major strengths, limitations, and strategies for complication avoidance is necessary for its safe and effective application. © Georg Thieme Verlag KG Stuttgart · New York.

A case of loss of consciousness with contralateral acute subdural haematoma during awake craniotomy

PubMed Central

Kamata, Kotoe; Maruyama, Takashi; Nitta, Masayuki; Ozaki, Makoto; Muragaki, Yoshihiro; Okada, Yoshikazu

2014-01-01

We are reporting the case of a 56-year-old woman who developed loss of consciousness during awake craniotomy. A thin subdural haematoma in the contralateral side of the craniotomy was identified with intraoperative magnetic resonance imaging and subsequently removed. Our case indicates that contralateral acute subdural haematoma could be a cause of deterioration of the conscious level during awake craniotomy. PMID:25301378

Awake craniotomy for tumor resection.

PubMed

Attari, Mohammadali; Salimi, Sohrab

2013-01-01

Surgical treatment of brain tumors, especially those located in the eloquent areas such as anterior temporal, frontal lobes, language, memory areas, and near the motor cortex causes high risk of eloquent impairment. Awake craniotomy displays major rule for maximum resection of the tumor with minimum functional impairment of the Central Nervous System. These case reports discuss the use of awake craniotomy during the brain surgery in Alzahra Hospital, Isfahan, Iran. A 56-year-old woman with left-sided body hypoesthesia since last 3 months and a 25-year-old with severe headache of 1 month duration were operated under craniotomy for brain tumors resection. An awake craniotomy was planned to allow maximum tumor intraoperative testing for resection and neurologic morbidity avoidance. The method of anesthesia should offer sufficient analgesia, hemodynamic stability, sedation, respiratory function, and also awake and cooperative patient for different neurological test. Airway management is the most important part of anesthesia during awake craniotomy. Tumor surgery with awake craniotomy is a safe technique that allows maximal resection of lesions in close relationship to eloquent cortex and has a low risk of neurological deficit.

Awake craniotomy for tumor resection

PubMed Central

Attari, Mohammadali; Salimi, Sohrab

2013-01-01

Surgical treatment of brain tumors, especially those located in the eloquent areas such as anterior temporal, frontal lobes, language, memory areas, and near the motor cortex causes high risk of eloquent impairment. Awake craniotomy displays major rule for maximum resection of the tumor with minimum functional impairment of the Central Nervous System. These case reports discuss the use of awake craniotomy during the brain surgery in Alzahra Hospital, Isfahan, Iran. A 56-year-old woman with left-sided body hypoesthesia since last 3 months and a 25-year-old with severe headache of 1 month duration were operated under craniotomy for brain tumors resection. An awake craniotomy was planned to allow maximum tumor intraoperative testing for resection and neurologic morbidity avoidance. The method of anesthesia should offer sufficient analgesia, hemodynamic stability, sedation, respiratory function, and also awake and cooperative patient for different neurological test. Airway management is the most important part of anesthesia during awake craniotomy. Tumor surgery with awake craniotomy is a safe technique that allows maximal resection of lesions in close relationship to eloquent cortex and has a low risk of neurological deficit. PMID:24223378

Seismicity pattern: an indicator of source region of volcanism at convergent plate margins

NASA Astrophysics Data System (ADS)

Špičák, Aleš; Hanuš, Václav; Vaněk, Jiří

2004-04-01

The results of detailed investigation into the geometry of distribution of earthquakes around and below the volcanoes Korovin, Cleveland, Makushin, Yake-Dake, Oshima, Lewotobi, Fuego, Sangay, Nisyros and Montagne Pelée at convergent plate margins are presented. The ISC hypocentral determinations for the period 1964-1999, based on data of global seismic network and relocated by Engdahl, van der Hilst and Buland, have been used. The aim of this study has been to contribute to the solution of the problem of location of source regions of primary magma for calc-alkaline volcanoes spatially and genetically related to the process of subduction. Several specific features of seismicity pattern were revealed in this context. (i) A clear occurrence of the intermediate-depth aseismic gap (IDAG) in the Wadati-Benioff zone (WBZ) below all investigated active volcanoes. We interpret this part of the subducted slab, which does not contain any teleseismically recorded earthquake with magnitude greater than 4.0, as a partially melted domain of oceanic lithosphere and as a possible source of primary magma for calc-alkaline volcanoes. (ii) A set of earthquakes in the shape of a seismically active column (SAC) seems to exists in the continental wedge below volcanoes Korovin, Makushin and Sangay. The seismically active columns probably reach from the Earth surface down to the aseismic gap in the Wadati-Benioff zone. This points to the possibility that the upper mantle overlying the subducted slab does not contain large melted domains, displays an intense fracturing and is not likely to represent the site of magma generation. (iii) In the continental wedge below the volcanoes Cleveland, Fuego, Nisyros, Yake-Dake, Oshima and Lewotobi, shallow seismicity occurs down to the depth of 50 km. The domain without any earthquakes between the shallow seismically active column and the aseismic gap in the Wadati-Benioff zone in the depth range of 50-100 km does not exclude the melting of the mantle also above the slab. (iv) Any earthquake does not exist in the lithospheric wedge below the volcano Montagne Pelée. The source of primary magma could be located in the subducted slab as well as in the overlying mantle wedge. (v) Frequent aftershock sequences accompanying stronger earthquakes in the seismically active columns indicate high fracturing of the wedge below active volcanoes. (vi) The elongated shape of clusters of epicentres of earthquakes of seismically active columns, as well as stable parameters of the available fault plane solutions, seem to reflect the existence of dominant deeply rooted fracture zones below volcanoes. These facts also favour the location of primary magma in the subducting slab rather than in the overlying wedge. We suppose that melts advancing from the slab toward the Earth surface may trigger the observed earthquakes in the continental wedge that is critically pre-stressed by the process of subduction. However, for definitive conclusions it will be necessary to explain the occurrence of earthquake clusters below some volcanoes and the lack of seismicity below others, taking into account the uncertainty of focal depth determination from global seismological data in some regions.

Epidemiology of Moderate-to-Severe Penetrating Versus Closed Traumatic Brain Injury in the Iraq and Afghanistan Wars

DTIC Science & Technology

2012-01-01

Craniotomy 1.21 incision and drainage of cranial sinus 1.23 reopening of craniotomy site 1.24 other craniotomy 1.31 incision of cerebral meninges 1.39 other...Any intervention 401 (51.8) 102 (21.2) 503 (40.1) G0.0001 ICP monitoring 249 (32.2) 77 (16.0) 326 (26.0) G0.0001 Craniotomy 167 (21.6) 30 (6.2) 197

Awake craniotomy: improving the patient's experience.

PubMed

Potters, Jan-Willem; Klimek, Markus

2015-10-01

Awake craniotomy patients are exposed to various stressful stimuli while their attention and vigilance is important for the success of the surgery. We describe several recent findings on the perception of awake craniotomy patients and address nonpharmacological perioperative factors that enhance the experience of awake craniotomy patients. These factors could also be applicable to other surgical patients. Proper preoperative counseling gives higher patient satisfaction and should be individually tailored to the patient. Furthermore, there is a substantial proportion of patients who have significant pain or fear during an awake craniotomy procedure. There is a possibility that this could induce post-traumatic stress disorder or related symptoms. Preoperative preparation is of utmost importance in awake craniotomy patients, and a solid doctor-patient relationship is an important condition. Nonpharmacological intraoperative management should focus on reduction of fear and pain by adaptation of the environment and careful and well considered communication.

Cosmetic and functional reconstruction achieved using a split myofascial bone flap for pterional craniotomy. Technical note.

PubMed

Matsumoto, K; Akagi, K; Abekura, M; Ohkawa, M; Tasaki, O; Tomishima, T

2001-04-01

Cosmetic deformities that appear following pterional craniotomy are usually caused by temporal muscle atrophy, injury to the frontotemporal branch of the facial nerve, or bone pits in the craniotomy line. To resolve these problems during pterional craniotomy, an alternative method was developed in which a split myofascial bone flap and a free bone flap are used. The authors have used this method in the treatment of 40 patients over the last 3 years. Excellent cosmetic and functional results have been obtained. This method can provide wide exposure similar to that achieved using Yaşargil's interfascial pterional craniotomy, without limiting the operative field with a bulky temporal muscle flap.

Anaesthesia for awake craniotomy is safe and well-tolerated.

PubMed

Andersen, Jakob Hessel; Olsen, Karsten Skovgaard

2010-10-01

Awake craniotomy for tumour resection has been performed at Glostrup Hospital since 2004. We describe and discuss the various anaesthetic approaches for such surgery and retrospectively analyse the 44 planned awake craniotomies performed at Glostrup Hospital. The surgery falls into four phases: craniotomy, mapping, tumour resection and closing. Three methods are being used: monitored anaesthetic care, asleep-awake-asleep and asleep-awake (AA). Anaesthesia is induced and maintained with propofol and remifentanil. A laryngeal mask (LM) is used as an airway during the craniotomy phase. In the AA method, patients are mapped and the tumour is resected while the patient is awake. A total of 41 of 44 planned AA craniotomies were performed. Three had to be converted into general anaesthesia (GA) due to tight brain, leaking LM and tumour haemorrhage, respectively. The following complications were observed: bradycardia 10%, leaking LM 5%, nausea 10%, vomiting 5%, focal seizures 28%, generalized seizures 10%, hypoxia 2%, hypotension 5% and hypertension 2%. Our results comply well with the international literature in terms of complications related to haemodynamics, respiration, seizures, vomiting and nausea and in terms of patient satisfaction. Awake craniotomy is a well-tolerated procedure with potential benefits. More prospective randomized studies are required.

Nonopioid anesthesia for awake craniotomy: a case report.

PubMed

Wolff, Diane L; Naruse, Robert; Gold, Michele

2010-02-01

Awake craniotomy is becoming more popular as a neurosurgical technique that allows for increased tumor resection and decreased postoperative neurologic morbidity. This technique, however, presents many challenges to both the neurosurgeon and anesthetist. An ASA class II, 37-year-old man with recurrent oligodendroglioma presented for repeated craniotomy. Prior craniotomy under general anesthesia resulted in residual neurologic deficits. An awake craniotomy was planned to allow for intraoperative testing for maximum tumor resection and avoidance of neurologic morbidity. The patient was sedated with propofol, and bupivacaine was infiltrated for placement of Mayfield tongs and skin incision. Following exposure of brain tissue, propofol infusion was discontinued to allow for patient cooperation during the procedure. Speech, motor, and sensory testing occurred during tumor resection until resection stopped after onset of weakness in the right arm. The propofol infusion was resumed while the cranium was closed and Mayfield tongs removed. The patient was awake, alert, oriented, and able to move all extremities but had residual weakness in the right forearm. Awake craniotomy requires appropriate patient selection, knowledge of the surgeon's skill, and a thorough anesthesia plan. This case report discusses the clinical and anesthetic management for awake craniotomy and reviews the literature.

Awake Craniotomy: First-Year Experiences and Patient Perception.

PubMed

Joswig, Holger; Bratelj, Denis; Brunner, Thomas; Jacomet, Alfred; Hildebrandt, Gerhard; Surbeck, Werner

2016-06-01

Awake craniotomy for brain lesions in or near eloquent brain regions enables neurosurgeons to assess neurologic functions of patients intraoperatively, reducing the risk of permanent neurologic deficits and increasing the extent of resection. A retrospective review was performed of a consecutive series of patients with awake craniotomies in the first year of their introduction to our tertiary non-university-affiliated neurosurgery department. Operation time, complications, and neurologic outcome were assessed, and patient perception of awake craniotomy was surveyed using a mailed questionnaire. There were 24 awake craniotomies performed in 22 patients for low-grade/high-grade gliomas, cavernomas, and metastases (average 2 cases per month). Mean operation time was 205 minutes. Failure of awake craniotomy because of intraoperative seizures with subsequent postictal impaired testing or limited cooperation occurred in 2 patients. Transient neurologic deficits occurred in 29% of patients; 1 patient sustained a permanent neurologic deficit. Of the 18 patients (82%) who returned the questionnaire, only 2 patients recalled significant fear during surgery. Introducing awake craniotomy to a tertiary non-university-affiliated neurosurgery department is feasible and resulted in reasonable operation times and complication rates and high patient satisfaction. Copyright © 2016 Elsevier Inc. All rights reserved.

Workload Trend Analysis for the Military Graduate Medical Education Program in San Antonio

DTIC Science & Technology

2005-05-25

Procedures 57 Introduction and Methodology 57 Results and Discussion 58 Craniotomy 61 Introduction and Methodology 61 Results and Discussion 62...distribution of major vascular procedures by age group for FY 00-04 36. WHMC and BAMC craniotomies for FY 00-04 by age group 37. WHMC and BAMC FY 00-04...average craniotomies by age group compared to required average based on RRC requirement 38. WHMC and BAMC distribution of craniotomies by age group for

The history of craniotomy for headache treatment.

PubMed

Assina, Rachid; Sarris, Christina E; Mammis, Antonios

2014-04-01

Both the history of headache and the practice of craniotomy can be traced to antiquity. From ancient times through the present day, numerous civilizations and scholars have performed craniotomy in attempts to treat headache. Today, surgical intervention for headache management is becoming increasingly more common due to improved technology and greater understanding of headache. By tracing the evolution of the understanding of headache alongside the practice of craniotomy, investigators can better evaluate the mechanisms of headache and the therapeutic treatments used today.

Teaching and sustainably implementing awake craniotomy in resource-poor settings.

PubMed

Howe, Kathryn L; Zhou, Guosheng; July, Julius; Totimeh, Teddy; Dakurah, Thomas; Malomo, Adefolarin O; Mahmud, Muhammad R; Ismail, Nasiru J; Bernstein, Mark A

2013-12-01

Awake craniotomy for brain tumor resection has the benefit of avoiding a general anesthetic and decreasing associated costs (e.g., intensive care unit beds and intravenous line insertion). In low- and middle-income countries, significant resource limitations for the system and individual make awake craniotomy an ideal tool, yet it is infrequently used. We sought to determine if awake craniotomy could be effectively taught and implemented safely and sustainably in low- and middle-income countries. A neurosurgeon experienced in the procedure taught awake craniotomy to colleagues in China, Indonesia, Ghana, and Nigeria during the period 2007-2012. Patients were selected on the basis of suspected intraaxial tumor, absence of major dysphasia or confusion, and ability to tolerate the positioning. Data were recorded by the local surgeons and included preoperative imaging, length of hospital admission, final pathology, postoperative morbidity, and mortality. Awake craniotomy was performed for 38 cases of suspected brain tumor; most procedures were completed independently. All patients underwent preoperative computed tomography or magnetic resonance imaging. In 64% of cases, patients remained in the hospital <10 days. The most common pathology was high-grade glioma, followed by meningioma, low-grade glioma, and metastasis. No deaths occurred, and no case required urgent intubation. The most common perioperative and postoperative issue was seizure, with 1 case of permanent postoperative deficit. Awake craniotomy was successfully taught and implemented in 6 neurosurgical centers in China, Indonesia, Ghana, and Nigeria. Awake craniotomy is safe, resource-sparing, and sustainable. The data suggest awake craniotomy has the potential to significantly improve access to neurosurgical care in resource-challenged settings. Copyright © 2013 Elsevier Inc. All rights reserved.

Wedge assembly for electrical transformer component spacing

DOEpatents

Baggett, Franklin E.; Cage, W. Franklin

1991-01-01

A wedge assembly that is easily inserted between two surfaces to be supported thereby, and thereafter expanded to produce a selected spacing between those surfaces. This wedge assembly has two outer members that are substantially identical except that they are mirror images of each other. Oppositely directed faces of these of these outer members are substantially parallel for the purpose of contacting the surfaces to be separated. The outer faces of these outer members that are directed toward each other are tapered so as to contact a center member having complementary tapers on both faces. A washer member is provided to contact a common end of the outer members, and a bolt member penetrates this washer and is threadably received in a receptor of the center member. As the bolt member is threaded into the center member, the center member is drawn further into the gap between the outer members and thereby separates these outer members to contact the surfaces to be separated. In the preferred embodiment, the contacting surfaces of the outer member and the center member are provided with guide elements. The wedge assembly is described for use in separating the secondary windings from the laminations of an electrical power transformer.

Pediatric Awake Craniotomy for Brain Lesions.

PubMed

Akay, Ali; Rükşen, Mete; Çetin, H Yurday; Seval, H Özer; İşlekel, Sertaç

2016-01-01

Awake craniotomy is a special method to prevent motor deficits during the resection of lesions that are located in, or close to, functional areas. Although it is more commonly performed in adult patients, reports of pediatric cases undergoing awake craniotomy are limited in the literature. In our clinic, where we frequently use awake craniotomy in adult patients, we performed this method in 2 selected pediatric cases for lesion surgery. At an early age, these 2 cases diagnosed with epilepsy presented cerebral lesions, but since the lesions enclosed functional areas, surgical resection was not regarded as a treatment option at this time. In these 2 pediatric cases, we successfully completed lesion surgery with awake craniotomy. The method and the techniques employed during surgery are presented concomitant with other reports in the literature. © 2016 S. Karger AG, Basel.

Management of supratentorial cavernous malformations: craniotomy versus gammaknife radiosurgery.

PubMed

Shih, Yang-Hsin; Pan, David Hung-Chi

2005-02-01

Although craniotomy is the preferred treatment for symptomatic solitary supratentorial cavernous malformation (CM), radiosurgery is also an option. Our aim was to see which of these strategies was the most effective and under what circumstances. Of the 46 patients with solitary supratentorial CM that we retrospectively studied, 24 presented with seizures, 16 with focal neurological deficits due to intracerebral hemorrhage, and 6 with both seizures and bleeding. Sixteen were treated with craniotomy and 30 with gammaknife radiosurgery (GKRS). The main outcome measures for comparing craniotomy with GKRS were the proportion of postoperative seizure-free patients and the proportion of patients in whom no rebleeding occurred. Of patients presenting with seizures with/without bleeding, a significantly higher proportion of the craniotomy group than the GKRS group became and remained seizure-free (11/14 [79%] versus 4/16 [25%]; P < 0.002), and of those presenting with bleeding with/without seizures, a somewhat (though nonsignificantly) higher proportion did not rebleed (4/4 [100%] versus 12/18 [67%]) after surgery. The remaining 2 of the 16 craniotomy patients did not rebleed and had no residual tumor at follow up. Twelve of the 30 GKRS patients had evidence of tumor regression at follow up. In the clinical management of solitary supratentorial CM, craniotomy for lesionectomy resulted in better seizure control and rebleeding avoidance than GKRS.

Definition, evaluation, and management of brain relaxation during craniotomy.

PubMed

Li, J; Gelb, A W; Flexman, A M; Ji, F; Meng, L

2016-06-01

The term 'brain relaxation' is routinely used to describe the size and firmness of the brain tissue during craniotomy. The status of brain relaxation is an important aspect of neuroanaesthesia practice and is relevant to the operating conditions, retraction injury, and likely patient outcomes. Brain relaxation is determined by the relationship between the volume of the intracranial contents and the capacity of the intracranial space (i.e. a content-space relationship). It is a concept related to, but distinct from, intracranial pressure. The evaluation of brain relaxation should be standardized to facilitate clinical communication and research collaboration. Both advantageous and disadvantageous effects of the various interventions for brain relaxation should be taken into account in patient care. The outcomes that matter the most to patients should be emphasized in defining, evaluating, and managing brain relaxation. To date, brain relaxation has not been reviewed specifically, and the aim of this manuscript is to discuss the current approaches to the definition, evaluation, and management of brain relaxation, knowledge gaps, and targets for future research. © The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

How I do it: Awake craniotomy.

PubMed

Hill, Ciaran Scott; Severgnini, Flavio; McKintosh, Edward

2017-01-01

Awake craniotomy allows continuous assessment of a patient's clinical and neurological status during open brain surgery. This facilitates early detection of interference with eloquent cortex, and hence can allow a surgeon to maximize resection margins without compromising neurological function. Awake craniotomy requires an effective scalp blockade, intraoperative assessment, and a carefully co-ordinated theatre team. A variety of clinical and electrophysiological techniques can be used to assess cortical function. Effective scalp blockade and awake craniotomy provides the opportunity to intraoperatively assess cortical function in the awake patient, thus providing an important neurosurgical option for lesions near eloquent cortex.

Patients' perspective on awake craniotomy for brain tumors-single center experience in Brazil.

PubMed

Leal, Rafael Teixeira Magalhaes; da Fonseca, Clovis Orlando; Landeiro, Jose Alberto

2017-04-01

Awake craniotomy with brain mapping is the gold standard for eloquent tissue localization. Patients' tolerability and satisfaction have been shown to be high; however, it is a matter of debate whether these findings could be generalized, since patients across the globe have their own cultural backgrounds and may perceive and accept this procedure differently. We conducted a prospective qualitative study about the perception and tolerability of awake craniotomy in a population of consecutive brain tumor patients in Brazil between January 2013 and April 2015. Seventeen patients were interviewed using a semi-structured model with open-ended questions. Patients' thoughts were grouped into five categories: (1) overall perception: no patient considered awake craniotomy a bad experience, and most understood the rationale behind it. They were positively surprised with the surgery; (2) memory: varied from nothing to the entire surgery; (3) negative sensations: in general, it was painless and comfortable. Remarks concerning discomfort on the operating table were made; (4) postoperative recovery: perception of the postoperative period was positive; (5) previous surgical experiences versus awake craniotomy: patients often preferred awake surgery over other surgery under general anesthesia, including craniotomies. Awake craniotomy for brain tumors was well tolerated and yielded high levels of satisfaction in a population of patients in Brazil. This technique should not be avoided under the pretext of compromising patients' well-being.

Compression asphyxia in upright suspended position.

PubMed

Tumram, Nilesh Keshav; Ambade, Vipul Namdeorao; Dixit, Pradeep Gangadhar

2014-06-01

In compression asphyxia, the respiration is prevented by external pressure on the body. It is usually due to external force compressing the trunk due to heavy weight over chest/abdomen and is associated with internal injuries. In the present case, the victim was suspended in an upright position owing to wedging of the chest and the abdomen in the gap between 2 parallel bridges undergoing construction. There was neither any heavy weight over the body, nor was any external force applied over the trunk. Moreover, there was neither any severe blunt force injury nor any significant pathological natural disease contributing to the cause of death. The body was wedged in the gap between 2 static hard surfaces. The victim was unable to extricate himself from the position owing to impairment of cognitive responses and coordination due to influence of alcohol. The victim died as a result of "static" asphyxia due to compression of the chest and the abdomen. Compression asphyxia in upright suspended position under this circumstance is very rare and not reported previously to the best of our knowledge.

Craniotomy with endoscopic assistance in the treatment of nasopharygeal fibroangioma.

PubMed

Fu, Ji-di; Liu, Hao-cheng; Zhao, Shang-feng; Zhang, Jia-liang; Li, Yong; Ni, Xin; Yu, Chun-jiang

2010-05-20

Nasopharygeal fibroangioma (NPF) can be approached through lateral rhinotomy, the middle skull fossa approach and the transcranial-facial combined approach. It is complicated and thus results in more insults, and when adopted, the total resection rate of tumor is still low. The nasal endoscope is minimally invasive, the dead angles of a craniotomy, such as sphenoid sinus, maxillary sinus, and nasopharynx are easily approached by an endoscope. Lateral rhinotomy have to make facial incision and affects maxillary bone development. We combined the craniotomy and endoscopic approach intending to take advantages of the two approaches. Twelve NPF patients who underwent craniotomy with endoscopic assistance from March 2002 to July 2008 at the Beijing Tongren Hospital were selected. All patients were male. Their ages ranged from 11 to 33 years. The main symptoms were visual deterioration, exophthalmos, nasal obstruction, epistaxis and pharynx nasalis neoplasm. The diagnosis was based on CT, MRI and digital subtraction angiography (DSA). All patients had intracranial encroachment and all underwent DSA and embolism treatment were taken before surgery. Seven patients had a pterional craniotomy, five had a frontal-temporal-orbital-zygomatic craniotomy. Most of the tumor was resected piecemeal, then removed through the sphenoidal sinus. Finally, using an endoscope in the nasal cavity, tumor in nasal cavity was resected and removed through the sphenoidal sinus, observing the dead angle of the craniotomy and confirming that sinus drainage was unobstructed. The tumor was removed completely in 11 patients and partially resected in one patient because of hemorrhage. One patient had an infection after the operation and one patient had cerebrospinal rhinorrhea 3 years after surgery that was remediated by endoscopic repair. Craniotomy with endoscopic assistance in the treatment of NPF was minimally invasive, safe and efficient, and avoided facial incision.

Patient response to awake craniotomy - a summary overview.

PubMed

Milian, Monika; Tatagiba, Marcos; Feigl, Guenther C

2014-06-01

Awake craniotomy is a valuable procedure since it allows brain mapping and live monitoring of eloquent brain functions. The advantage of minimizing resource utilization is also emphasized by some physicians in North America. Data on how well an awake craniotomy is tolerated by patients and how much stress it creates is available from different studies, but this topic has not consequently been summarized in a review of the available literature. Therefore, it is the purpose of this review to shed more light on the still controversially discussed aspect of an awake craniotomy. We reviewed the available English literature published until December 2013 searching for studies that investigated patients' responses to awake craniotomies. Twelve studies, published between 1998 and 2013, including 396 patients with awake surgery were identified. Eleven of these 12 studies set the focus on the perioperative time, one study focused on the later postoperative time. The vast majority of patients felt well prepared and overall satisfaction with the procedure was high. In the majority of studies up to 30 % of the patients recalled considerable pain and 10-14 % experienced strong anxiety during the procedure. The majority of patients reported that they would undergo an awake craniotomy again. A post traumatic stress disorder was present neither shortly nor years after surgery. However, a normal human response to such an exceptional situation can for instance be the delayed appearance of unintentional distressing recollections of the event despite the patients' satisfaction concerning the procedure. For selected patients, an awake craniotomy presents the best possible way to reduce the risk of surgery related neurological deficits. However, benefits and burdens of this type of procedure should be carefully considered when planning an awake craniotomy and the decision should serve the interests of the patient.

Integrative Review: Post-Craniotomy Pain in the Brain Tumor Patient

PubMed Central

Guilkey, Rebecca Elizabeth; Von Ah, Diane; Carpenter, Janet S.; Stone, Cynthia; Draucker, Claire B.

2015-01-01

Aim To conduct an integrative review to examine evidence of pain and associated symptoms in adult (≥ 21 years of age), post-craniotomy, brain tumor patients hospitalized on intensive care units. Background Healthcare providers believe craniotomies are less painful than other surgical procedures. Understanding how post-craniotomy pain unfolds over time will help inform patient care and aid in future research and policy development. Design Systematic literature search to identify relevant literature. Information abstracted using the Theory of Unpleasant Symptoms’ concepts of influencing factors, symptom clusters and patient performance. Inclusion criteria were indexed, peer-reviewed, full-length, English-language articles. Keywords were ‘traumatic brain injury,’ ‘pain, post-operative,’ ‘brain injuries,’ ‘postoperative pain,’ ‘craniotomy,’ ‘decompressive craniectomy,’ and ‘trephining.’ Data sources Medline, OVID, PubMed and CINAHL databases from 2000 – 2014. Review Method Cooper’s five-stage integrative review method was used to assess and synthesize literature. Results The search yielded 115 manuscripts, with 26 meeting inclusion criteria. Most studies were randomized, controlled trials conducted outside of the United States. All tested pharmacological pain interventions. Post-craniotomy brain tumor pain was well-documented and associated with nausea, vomiting and changes in blood pressure and impacted patient length of hospital stay, but there was no consensus for how best to treat such pain. Conclusion The Theory of Unpleasant Symptoms provided structure to the search. Post-craniotomy pain is experienced by patients, but associated symptoms and impact on patient performance remain poorly understood. Further research is needed to improve understanding and management of post-craniotomy pain in this population. PMID:26734710

Patient acceptance of awake craniotomy.

PubMed

Wrede, Karsten H; Stieglitz, Lennart H; Fiferna, Antje; Karst, Matthias; Gerganov, Venelin M; Samii, Madjid; von Gösseln, Hans-Henning; Lüdemann, Wolf O

2011-12-01

The aim of this study was to objectively assess the patients' acceptance for awake craniotomy in a group of neurosurgical patients, who underwent this procedure for removal of lesions in or close to eloquent brain areas. Patients acceptance for awake craniotomy under local anesthesia and conscious sedation was assessed by a formal questionnaire (PPP33), initially developed for general surgery patients. The results are compared to a group of patients who had brain surgery under general anesthesia and to previously published data. The awake craniotomy (AC) group consisted of 37 male and 9 female patients (48 craniotomies) with age ranging from 18 to 71 years. The general anesthesia (GA) group consisted of 26 male and 15 female patients (43 craniotomies) with age ranging from 26 to 83 years. All patients in the study were included in the questionnaire analysis. In comparison to GA the overall PPP33 score for AC was higher (p=0.07), suggesting better overall acceptance for AC. The subscale scores for AC were also significantly better compared to GA for the two subscales "postoperative pain" (p=0.02) and "physical disorders" (p=0.01) and equal for the other 6 subscales. The results of the overall mean score and the scores for the subscales of the PPP33 questionnaire verify good patients' acceptance for AC. Previous studies have shown good patients' acceptance for awake craniotomy, but only a few times using formal approaches. By utilizing a formal questionnaire we could verify good patient acceptance for awake craniotomy for the treatment of brain tumors in or close to eloquent areas. This is a novel approach that substantiates previously published experiences. Copyright © 2011 Elsevier B.V. All rights reserved.

Intracellular magnetophoresis of amyloplasts and induction of root curvature

NASA Technical Reports Server (NTRS)

Kuznetsov, O. A.; Hasenstein, K. H.

1996-01-01

High-gradient magnetic fields (HGMFs) were used to induce intracellular magnetophoresis of amyloplasts. The HGMFs were generated by placing a small ferromagnetic wedge into a uniform magnetic field or at the gap edge between two permanent magnets. In the vicinity of the tip of the wedge the dynamic factor of the magnetic field, delta(H2/2), was about 10(9) Oe2.cm-1, which subjected the amyloplasts to a force comparable to that of gravity. When roots of 2-d-old seedlings of flax (Linum usitatissimum L.) were positioned vertically and exposed to an HGMF, curvature away from the wedge was transient and lasted approximately 1 h. Average curvature obtained after placing magnets, wedge and seedlings on a 1-rpm clinostat for 2 h was 33 +/- 5 degrees. Roots of horizontally placed control seedlings without rotation curved about 47 +/- 4 degrees. The time course of curvature and changes in growth rate were similar for gravicurvature and for root curvature induced by HGMFs. Microscopy showed displacement of amyloplasts in vitro and in vivo. Studies with Arabidopsis thaliana (L.) Heynh. showed that the wild type responded to HGMFs but the starchless mutant TC7 did not. The data indicate that a magnetic force can be used to study the gravisensing and response system of roots.

[Comparison of the intracranial pressure value in patients with hypertensive intracerebral hemorrhage treated with traditional craniotomy and puncture drainage].

PubMed

Song, Shao-jun; Fei, Zhou; Zhang, Xiang

2003-09-01

To compare the difference of intracranial pressure (ICP) in patients with hypertensive intracerebral hemorrhage (HICH) treated with two surgical procedures, traditional craniotomy and puncture drainage. One hundred and twelve cases with HICH were randomly divided into two groups. In one group, 60 patients were operated by traditional craniotomy and in another group, 52 cases by puncture drainage and urokinase treatment. In the meantime, ICP was monitored by placing catheter in lateral ventricle on the contralateral side of the hemorrhage. ICP values were recorded after operation at once, at 24 hours, 72 hours and 1 week. Although all the patients showed increased ICP, the increasing degree in patients treated with traditional craniotomy had lower ICP values (P<0.05 or P<0.01). Traditional craniotomy has advantages over puncture drainage for patients with HICH at least with respect to decreasing ICP.

[Awake craniotomy: analysis of complicated cases].

PubMed

Kulikov, A S; Kobyakov, G L; Gavrilov, A G; Lubnin, A Yu

2015-01-01

Awake craniotomy is recognized as method that can decrease the frequency of neurological complications after surgery for gliomas located near eloquent brain regions. Unfortunately good neurological outcome can't be ensured even by using of this technique. This paper discusses reasons and possible ways of prevention of such complications. 162 awake craniotomies were performed in our clinic. 152 of patients were discharged from the clinic with good outcome. In 10 (6%) cases sustained severe neurological deficit was noted. These complications were associated with anatomic or ischemic injury of subcortical pathways and internal capsule. Awake craniotomy is effective instrument of brain language mapping and prevention of neurological deterioration. Severe neurological complications of awake craniotomy are associated with underestimate neurosurgical risks, especially in terms of blood vessel injury and depth of resection. The main way of prevention of such complications is meticulous planning of operation and adequate using of mapping facilities.

Pediatric awake craniotomy for seizure focus resection with dexmedetomidine sedation-a case report.

PubMed

Sheshadri, Veena; Chandramouli, B A

2016-08-01

Resection of lesions near the eloquent cortex of brain necessitates awake craniotomy to reduce the risk of permanent neurologic deficits during surgery. There are limited reports of anesthetic management of awake craniotomy in pediatric patients. This report is on use of dexmedetomidine sedation for awake craniotomy in a 11-year-old child, without any airway adjuncts throughout the procedure. Dexmedetomidine infusion administered at a dosage of 0.2 to 0.7μg kg(-1) h(-1) provided adequate sedation for the entire procedure. There were no untoward incidents or any interference with electrocorticography, intraoperative stimulation, and functional mapping. Adequate preoperative visits and counseling of patient and parents regarding course and nature of events along with well-planned intraoperative management are of utmost importance in a pediatric age group for successful intraoperative awake craniotomy. Copyright © 2016 Elsevier Inc. All rights reserved.

Combination of Continuous Dexmedetomidine Infusion with Titrated Ultra-Low-Dose Propofol-Fentanyl for an Awake Craniotomy

PubMed Central

Das, Samaresh; Al-Mashani, Ali; Suri, Neelam; Salhotra, Neeraj; Chatterjee, Nilay

2016-01-01

An awake craniotomy is a continuously evolving technique used for the resection of brain tumours from the eloquent cortex. We report a 29-year-old male patient who presented to the Khoula Hospital, Muscat, Oman, in 2016 with a two month history of headaches and convulsions due to a space-occupying brain lesion in close proximity with the left motor cortex. An awake craniotomy was conducted using a scalp block, continuous dexmedetomidine infusion and a titrated ultra-low-dose of propofolfentanyl. The patient remained comfortable throughout the procedure and the intraoperative neuropsychological tests, brain mapping and tumour resection were successful. This case report suggests that dexmedetomidine in combination with titrated ultra-low-dose propofolfentanyl are effective options during an awake craniotomy, ensuring optimum sedation, minimal disinhibition and a rapid recovery. To the best of the authors’ knowledge, this is the first awake craniotomy conducted successfully in Oman. PMID:27606116

Awake Craniotomy: A New Airway Approach.

PubMed

Sivasankar, Chitra; Schlichter, Rolf A; Baranov, Dimitry; Kofke, W Andrew

2016-02-01

Awake craniotomies have been performed regularly at the University of Pennsylvania since 2004. Varying approaches to airway management are described for this procedure, including intubation with an endotracheal tube and use of a laryngeal mask airway, simple facemask, or nasal cannula. In this case series, we describe the successful use (i.e., no need for endotracheal intubation related to inadequate gas exchange) of bilateral nasopharyngeal airways in 90 patients undergoing awake craniotomies. The use of nasopharyngeal airways can ease the transition between the asleep and awake phases of the craniotomy without the need to stimulate the airway. Our purpose was to describe our experience and report adverse events related to this technique.

Diagnostic and prognostic value of procalcitonin for early intracranial infection after craniotomy

PubMed Central

Yu, Y.; Li, H.J.

2017-01-01

Intracranial infection is a common clinical complication after craniotomy. We aimed to explore the diagnostic and prognostic value of dynamic changing procalcitonin (PCT) in early intracranial infection after craniotomy. A prospective study was performed on 93 patients suspected of intracranial infection after craniotomy. Routine peripheral venous blood was collected on the day of admission, and C reactive protein (CRP) and PCT levels were measured. Cerebrospinal fluid (CSF) was collected for routine biochemical, PCT and culture assessment. Serum and CSF analysis continued on days 1, 2, 3, 5, 7, 9, and 11. The patients were divided into intracranial infection group and non-intracranial infection group; intracranial infection group was further divided into infection controlled group and infection uncontrolled group. Thirty-five patients were confirmed with intracranial infection after craniotomy according to the diagnostic criteria. The serum and cerebrospinal fluid PCT levels in the infected group were significantly higher than the non-infected group on day 1 (P<0.05, P<0.01). The area under curve of receiver operating characteristics was 0.803 for CSF PCT in diagnosing intracranial infection. The diagnostic sensitivity and specificity of CSF PCT was superior to other indicators. The serum and CSF PCT levels have potential value in the early diagnosis of intracranial infection after craniotomy. Since CSF PCT levels have higher sensitivity and specificity, dynamic changes in this parameter could be used for early detection of intracranial infection after craniotomy, combined with other biochemical indicators. PMID:28443989

Awake craniotomy and multilingualism: language testing during anaesthesia for awake craniotomy in a bilingual patient.

PubMed

Costello, T G

2014-08-01

An awake craniotomy for epilepsy surgery is presented where a bilingual patient post-operatively reported temporary aphasia of his first language (Spanish). This case report discusses the potential causes for this clinical presentation and methods to prevent the occurrence of this in future patients undergoing this form of surgery. Copyright © 2014 Elsevier Ltd. All rights reserved.

P10.05 Establishment of team work awake craniotomy: clinical experience in Taiwan

PubMed Central

Chen, P.; Chang, W.; Chao, Y.; Toh, C.; Wei, K.

2017-01-01

Abstract Introduction: Awake craniotomy provides the opportunity to maximize both extent of resection and preservation of neurological function. Serial preoperative and postoperative neurobehavial evaluation, magnetic resonance image examination and intraoperative task investigation need multidisciplinary experts to cooperate. Materials and Methods: From 2013, we gradually establish our team for awake craniotomy. Patient who had brain tumor with the symptom of aphasia or hemiparesis and are willing to cooperate would be entered the protocol of awake craniotomy. Patients would receive complete preoperative neurobehavial examination by psychologists and speech therapists and magnetic resonance image included diffuse tensor image. During operation, Patients went through asleep-awake-asleep anesthetic techniques. Direct electric stimulation was used for both cortical and subcortical mapping. Navigation included information of lesion and important fiber tract guided the direction of excision. Rehabilitation doctor performed the tasks and decided the positive response caused by stimulation or excisional procedure. After operation, post-operative image and neurobehavial examination would be performed within one week, 3 months, 6 months and one year later Results: We scheduled awake craniotomy on almost every Tuesday. In recent 89 patients who received awake craniotomy, Twenty-five participants with recurrent tumor underwent the operation. Seven patients received twice and one patient received three times of awake craniotomy. Two patients had controllable intraoperative seizure attack. Early termination of awake status was found in two patients due to general discomfort. Patients with modest preoperative performance status still benefit from the operation. Neurobehavioral functions improved over time and some specific feature correlate to certain aspect of quality of life. The grading of tumor and the extension of resection influence the recovery of neurobehavioral functions and progression free survival considerably. Conclusions: Awake craniotomy is a feasible and effective way to improve not only patient`s survival rate but also quality of life. A team with neurosurgeon, rehabilitation doctor, speech therapist, psychologist, anesthesiologist, nurses and other specialist is important to improve the quality of clinical care for patient who received awake craniotomy. This study is supported by Chang Gung Memorial Hospital with grant number: CMRPG3D0243

Awake craniotomy in a depressed and agitated patient

PubMed Central

Al Shuaibi, Khalid M.

2010-01-01

Depressed patients with brain tumors are often not referred to awake craniotomy because of concern of uncooperation which may increase the risk of perioperative complications. This report describes an interesting case of awake craniotomy for frontal lobe glioma in a 41-year-old woman undergoing language and motor mapping intraoperatively. As she was fearful and apprehensive and was on antidepressant therapy to control depression, the author adopted general anesthesia with laryngeal mask airway during initial stage of skull pinning and craniotomy procedures. Then, the patient reverted to awake state to continue the intended neurosurgical procedure. The patient tolerated the situation satisfactorily and was cooperative till the finish, without any event. PMID:25885087

Hemi-wedge osteotomy in the management of large angular deformities around the knee joint.

PubMed

El-Alfy, Barakat Sayed

2016-08-01

Angular deformity around the knee joint is a common orthopedic problem. Many options are available for the management of such problem with varying degrees of success and failure. The aim of the present study was to assess the results of hemi-wedge osteotomy in the management of big angular deformities about the knee joint. Twenty-eight limbs in 21 patients with large angular deformities around the knee joint were treated by the hemi-wedge osteotomy technique. The ages ranged from 12 to 43 years with an average of 19.8 years. The deformity ranged from 20° to 40° with a mean of 30.39° ± 5.99°. The deformities were genu varum in 12 cases and genu valgum in 9 cases. Seven cases had bilateral deformities. Small wedge was removed from the convex side of the bone and put in the gap created in the other side after correction of the deformity. At the final follow-up, the deformity was corrected in all cases except two. Full range of knee movement was regained in all cases. The complications included superficial wound infection in two cases, overcorrection in one case, pain along the lateral aspect of the knee in one case and recurrence of the deformity in one case. No cases were complicated by nerve injury or vascular injury. Hemi-wedge osteotomy is a good method for treatment of deformities around the knee joint. It can correct large angular deformities without major complications.

Surgical Management of Dural Arteriovenous Fistula After Craniotomy: Case Report and Review of Literature.

PubMed

Pabaney, Aqueel H; Robin, Adam M; Basheer, Azam; Malik, Ghaus

2016-05-01

Development of dural arteriovenous fistula (dAVF) with cortical venous drainage at the site of previous craniotomy is a rare manifestation of nontraumatic subarachnoid hemorrhage (SAH). The authors present a case of postcraniotomy dAVF formation and discuss plausible underlying mechanisms of fistula formation and treatment options as well as review the literature. A 62-year-old man, who had undergone craniotomy 2 decades previously, presented with SAH. Workup revealed a low-flow dAVF with leptomeningeal venous drainage at the posterior margin of the craniotomy. Surgical resection of fistula was undertaken that resulted in cure. Spontaneous SAH in patients with a previous history of an intracranial procedure (e.g., craniotomy, ventriculostomy) should prompt detailed imaging evaluation. In the absence of vascular disease, meticulous review of the angiogram must be undertaken to rule out dAVF at the procedure site and it should be treated definitively. Copyright © 2016 Elsevier Inc. All rights reserved.

Immediate titanium mesh cranioplasty for treatment of post-craniotomy infections

PubMed Central

Wind, Joshua J.; Ohaegbulam, Chima; Iwamoto, Fabio M.; Black, Peter McL.; Park, John K.

2011-01-01

OBJECTIVE Post craniotomy infections have generally been treated by debridement of infected tissues, disposal of the bone flap, and delayed cranioplasty several months later to repair the resulting skull defect. Debridement followed by retention of the bone flap has also been advocated. Here we propose an alternative operative strategy for the treatment of post craniotomy infections. METHODS Two patients presenting with clinical and radiographic signs and symptoms of post craniotomy infections were treated by debridement, bone flap disposal, and immediate titanium mesh cranioplasty. The patients were subsequently administered antibiotics and their clinical courses were followed. RESULTS The patients treated in this fashion did not have recurrence of their infections during three-year follow-up periods. CONCLUSIONS Surgical debridement, bone flap disposal and immediate titanium mesh cranioplasty may be a suitable option for the treatment of post craniotomy infections. This treatment strategy facilitates the eradication of infectious sources and obviates the risks and costs associated with a second surgical procedure. PMID:22120410

Awake craniotomy

PubMed Central

Bajunaid, Khalid M.; Ajlan, Abdulrazag M.

2015-01-01

Objective: To report the personal experiences of patients undergoing awake craniotomy for brain tumor resection. Methods: We carried out a qualitative descriptive survey of patients’ experiences with awake craniotomies for brain tumor resection. The survey was conducted through a standard questionnaire form after the patient was discharged from the hospital. Results: Of the 9 patients who met the inclusion criteria and underwent awake craniotomy, 3 of those patients reported no recollection of the operation. Five patients had auditory recollections from the operation. Two-thirds (6/9) reported that they did not perceive pain. Five patients remembered the head clamp fixation, and 2 of those patients classified the pain from the clamp as moderate. None of the patients reported that the surgery was more difficult than anticipated. Conclusion: Awake craniotomy for surgical resection of brain tumors was well tolerated by patients. Most patients reported that they do not recall feeling pain during the operation. However, we feel that further work and exploration are needed in order to achieve better control of pain and discomfort during these types of operations. PMID:26166593

Scalp Block for Awake Craniotomy in a Patient With a Frontal Bone Mass: A Case Report

PubMed Central

Amiri, Hamid Reza; Kouhnavard, Marjan; Safari, Saeid

2012-01-01

“Anesthesia” for awake craniotomy is a unique clinical condition that requires the anesthesiologist to provide changing states of sedation and analgesia, to ensure optimal patient comfort without interfering with electrophysiologic monitoring and patient cooperation, and also to manipulate cerebral and systemic hemodynamics while guaranteeing adequate ventilation and patency of airways. Awake craniotomy is not as popular in developing countries as in European countries. This might be due to the lack of information regarding awake craniotomy and its benefits among the neurosurgeons and anesthetists in developing countries. From the economic perspective, this procedure may decrease resource utilization by reducing the use of invasive monitoring, the duration of the operation, and the length of postoperative hospital stay. All these reasons also favor its use in the developing world, where the availability of resources still remains a challenge. In this case report we presented a successful awake craniotomy in patient with a frontal bone mass. PMID:24904791

Awake craniotomy. A patient`s perspective.

PubMed

Bajunaid, Khalid M; Ajlan, Abdulrazag M

2015-07-01

To report the personal experiences of patients undergoing awake craniotomy for brain tumor resection. We carried out a qualitative descriptive survey of patients` experiences with awake craniotomies for brain tumor resection. The survey was conducted through a standard questionnaire form after the patient was discharged from the hospital. Of the 9 patients who met the inclusion criteria and underwent awake craniotomy, 3 of those patients reported no recollection of the operation. Five patients had auditory recollections from the operation. Two-thirds (6/9) reported that they did not perceive pain. Five patients remembered the head clamp fixation, and 2 of those patients classified the pain from the clamp as moderate. None of the patients reported that the surgery was more difficult than anticipated. Awake craniotomy for surgical resection of brain tumors was well tolerated by patients. Most patients reported that they do not recall feeling pain during the operation. However, we feel that further work and exploration are needed in order to achieve better control of pain and discomfort during these types of operations.

Spreading Depolarizations Have Prolonged Direct Current Shifts and Are Associated with Poor Outcome in Brain Trauma

DTIC Science & Technology

2011-01-01

prognosis. Keywords: cortical spreading depression; electroencephalography; craniotomy ; signal processing; acute brain injury Introduction Cortical...Mannheim, Germany). Inclusion criteria were the clinical decision for craniotomy for lesion evacuation and/or decompression and age ~ 18 years...externalized through a burr hole in the skull (if the bone flap was replaced) and tu nne lied beneath the scalp to exit 2-3 em from the craniotomy

Infections in patients undergoing craniotomy: risk factors associated with post-craniotomy meningitis.

PubMed

Kourbeti, Irene S; Vakis, Antonis F; Ziakas, Panayiotis; Karabetsos, Dimitris; Potolidis, Evangelos; Christou, Silvana; Samonis, George

2015-05-01

OBJECT The authors performed a prospective study to define the prevalence and microbiological characteristics of infections in patients undergoing craniotomy and to clarify the risk factors for post-craniotomy meningitis. METHODS Patients older than 18 years who underwent nonstereotactic craniotomies between January 2006 and December 2008 were included. Demographic, clinical, laboratory, and microbiological data were systemically recorded. Patient characteristics, craniotomy type, and pre- and postoperative variables were evaluated as risk factors for meningitis RESULTS Three hundred thirty-four procedures were analyzed (65.6% involving male patients). Traumatic brain injury was the most common reason for craniotomy. Almost 40% of the patients developed at least 1 infection. Ventilator-associated pneumonia (VAP) was the most common infection recorded (22.5%) and Acinetobacter spp. were isolated in 44% of the cases. Meningitis was encountered in 16 procedures (4.8%), and CSF cultures were positive for microbial growth in 100% of these cases. Gram-negative pathogens (Acinetobacter spp., Klebsiella spp., Pseudomonas aeruginosa, Enterobacter cloaceae, Proteus mirabilis) represented 88% of the pathogens. Acinetobacter and Klebsiella spp. demonstrated a high percentage of resistance in several antibiotic classes. In multivariate analysis, the risk for meningitis was independently associated with perioperative steroid use (OR 11.55, p = 0.005), CSF leak (OR 48.03, p < 0.001), and ventricular drainage (OR 70.52, p < 0.001). CONCLUSIONS Device-related postoperative communication between the CSF and the environment, CSF leak, and perioperative steroid use were defined as risk factors for meningitis in this study. Ventilator-associated pneumonia was the most common infection overall. The offending pathogens presented a high level of resistance to several antibiotics.

Incidence, Risk Factors and Consequences of Emergence Agitation in Adult Patients after Elective Craniotomy for Brain Tumor: A Prospective Cohort Study

PubMed Central

Chen, Lu; Xu, Ming; Li, Gui-Yun; Cai, Wei-Xin; Zhou, Jian-Xin

2014-01-01

Emergence agitation is a frequent complication that can have serious consequences during recovery from general anesthesia. However, agitation has been poorly investigated in patients after craniotomy. In this prospective cohort study, adult patients were enrolled after elective craniotomy for brain tumor. The sedation-agitation scale was evaluated during the first 12 hours after surgery. Agitation developed in 35 of 123 patients (29%). Of the agitated patients, 28 (80%) were graded as very and dangerously agitated. By multivariate stepwise logistic regression analysis, independent predictors for agitation included male sex, history of long-term use of anti-depressant drugs or benzodiazepines, frontal approach of the operation, method and duration of anesthesia and presence of endotracheal intubation. Total intravenous anesthesia and balanced anesthesia with short duration were protective factors. Emergence agitation was associated with self-extubation (8.6% vs 0%, P = 0.005). Sedatives were administered more in agitated patients than non-agitated patients (85.7% vs 6.8%, P<0.001). In conclusion, emergence agitation was a frequent complication in patients after elective craniotomy for brain tumors. The clarification of risk factors could help to identify the high-risk patients, and then to facilitate the prevention and treatment of agitation. For patients undergoing craniotomy, greater attention should be paid to those receiving a frontal approach for craniotomy and those anesthetized under balanced anesthesia with long duration. More researches are warranted to elucidate whether total intravenous anesthesia could reduce the incidence of agitation after craniotomy. Trial Registration ClinicalTrials.gov NCT00590499. PMID:25493435

Craniotomy: true sham for traumatic brain injury, or a sham of a sham?

PubMed

Cole, Jeffrey T; Yarnell, Angela; Kean, William S; Gold, Eric; Lewis, Bobbi; Ren, Ming; McMullen, David C; Jacobowitz, David M; Pollard, Harvey B; O'Neill, J Timothy; Grunberg, Neil E; Dalgard, Clifton L; Frank, Joseph A; Watson, William D

2011-03-01

Abstract Neurological dysfunction after traumatic brain injury (TBI) is caused by both the primary injury and a secondary cascade of biochemical and metabolic events. Since TBI can be caused by a variety of mechanisms, numerous models have been developed to facilitate its study. The most prevalent models are controlled cortical impact and fluid percussion injury. Both typically use "sham" (craniotomy alone) animals as controls. However, the sham operation is objectively damaging, and we hypothesized that the craniotomy itself may cause a unique brain injury distinct from the impact injury. To test this hypothesis, 38 adult female rats were assigned to one of three groups: control (anesthesia only); craniotomy performed by manual trephine; or craniotomy performed by electric dental drill. The rats were then subjected to behavioral testing, imaging analysis, and quantification of cortical concentrations of cytokines. Both craniotomy methods generate visible MRI lesions that persist for 14 days. The initial lesion generated by the drill technique is significantly larger than that generated by the trephine. Behavioral data mirrored lesion volume. For example, drill rats have significantly impaired sensory and motor responses compared to trephine or naïve rats. Finally, of the seven tested cytokines, KC-GRO and IFN-γ showed significant increases in both craniotomy models compared to naïve rats. We conclude that the traditional sham operation as a control confers profound proinflammatory, morphological, and behavioral damage, which confounds interpretation of conventional experimental brain injury models. Any experimental design incorporating "sham" procedures should distinguish among sham, experimentally injured, and healthy/naïve animals, to help reduce confounding factors.

Technical Aspects of Awake Craniotomy with Mapping for Brain Tumors in a Limited Resource Setting.

PubMed

Leal, Rafael Teixeira Magalhaes; Barcellos, Bruno Mendonça; Landeiro, Jose Alberto

2018-05-01

Brain tumor surgery near or within eloquent regions is increasingly common and is associated with a high risk of neurologic injury. Awake craniotomy with mapping has been shown to be a valid method to preserve neurologic function and increase the extent of resection. However, the technique used varies greatly among centers. Most count on professionals such as neuropsychologists, speech therapists, neurophysiologists, or neurologists to help in intraoperative patient evaluation. We describe our technique with the sole participation of neurosurgeons and anesthesiologists. A retrospective review of 19 patients who underwent awake craniotomies for brain tumors between January 2013 and February 2017 at a tertiary university hospital was performed. We sought to identify and describe the most critical stages involved in this surgery as well as show the complications associated with our technique. Preoperative preparation, positioning, anesthesia, brain mapping, resection, and management of seizures and pain were stages deemed relevant to the accomplishment of an awake craniotomy. Sixteen percent of the patients developed new postoperative deficit. Seizures occurred in 24%. None led to awake craniotomy failure. We provide a thorough description of the technique used in awake craniotomies with mapping used in our institution, where the intraoperative patient evaluation is carried out solely by neurosurgeons and anesthesiologists. The absence of other specialized personnel and equipment does not necessarily preclude successful mapping during awake craniotomy. We hope to provide helpful information for those who wish to offer function-guided tumor resection in their own centers. Copyright © 2018 Elsevier Inc. All rights reserved.

Development of a safe and pragmatic awake craniotomy program at Maine Medical Center.

PubMed

Rughani, Anand I; Rintel, Theodor; Desai, Rajiv; Cushing, Deborah A; Florman, Jeffrey E

2011-01-01

Awake craniotomy offers an excellent means of performing intraoperative mapping and optimizing surgical resection of brain tumors. Awake craniotomy relies on a strong collaboration between anesthesiologists, neurosurgeons, and operating room staff. The authors recently introduced awake craniotomy for tumor resection at the Maine Medical Center and propose that it can be performed safely, effectively, and efficiently in a high-volume community hospital. We describe a practical approach to performing awake craniotomy involving streamlined anesthetic protocols and simplified intraoperative testing parameters in a carefully selected group of patients. Our first 25 patients are retrospectively reviewed with particular attention to the anesthetic protocol, the extent of resection, the operative time, post-operative complications, the length of hospitalization, and their functional status at follow-up. The authors established an anesthetic protocol based primarily on midazolam, fentanyl, propofol, and local anesthetic. The authors note that all but one patient was able to tolerate the awake procedure. Gross total resection was achieved in nearly 80% of patients with a glial tumor. Operative time was short, averaging 159 minutes of entire anesthesia care. Length of stay averaged 3.7 days. Persistent new post-operative deficits were noted in 2 of 25 patients. There was no substantial difference in total hospital charges for patients undergoing awake craniotomy when compared to a matched historical control. With attention focused on patient selection and a streamlined anesthetic protocol, the authors were able to successfully implement an awake craniotomy protocol in a community setting with satisfying results, including low operative morbidity, short operative times, low anesthetic complications, and excellent patient tolerance.

Anaesthesia for awake craniotomy: A retrospective study of 54 cases.

PubMed

Sokhal, Navdeep; Rath, Girija Prasad; Chaturvedi, Arvind; Dash, Hari Hara; Bithal, Parmod Kumar; Chandra, P Sarat

2015-05-01

The anaesthetic challenge of awake craniotomy is to maintain adequate sedation, analgesia, respiratory and haemodynamic stability in an awake patient who should be able to co-operate during intraoperative neurological assessment. The current literature, sharing the experience on awake craniotomy, in Indian context, is minimal. Hence, we carried out a retrospective study with the aim to review and analyse the anaesthetic management and perioperative complications in patients undergoing awake craniotomy, at our centre. Medical records of 54 patients who underwent awake craniotomy for intracranial lesions over a period of 10 years were reviewed, retrospectively. Data regarding anaesthetic management, intraoperative complications and post-operative course were recorded. Propofol (81.5%) and dexmedetomidine (18.5%) were the main agents used for providing conscious sedation to facilitate awake craniotomy. Hypertension (16.7%) was the most commonly encountered complication during intraoperative period, followed by seizures (9.3%), desaturation (7.4%), tight brain (7.4%), and shivering (5.6%). The procedure had to be converted to general anaesthesia in one of patients owing to refractory brain bulge. The incidence of respiratory and haemodynamic complications were comparable in the both groups (P > 0.05). There was less incidence of intraoperative seizures in patients who received propofol (P = 0.03). In post-operative period, 20% of patients developed new motor deficit. Mean intensive care unit stay was 2.8 ± 1.9 day (1-14 days) and mean hospital stay was 7.0 ± 5.0 day (3-30 days). 'Conscious sedation' was the technique of choice for awake craniotomy, at our institute. Fentanyl, propofol, and dexmedetomidine were the main agents used for this purpose. Patients receiving propofol had less incidence of intraoperative seizure. Appropriate selection of patients, understanding the procedure of surgery, and judicious use of sedatives or anaesthetic agents are key to the success for awake craniotomy as a procedure.

Anaesthesia for awake craniotomy: A retrospective study of 54 cases

PubMed Central

Sokhal, Navdeep; Rath, Girija Prasad; Chaturvedi, Arvind; Dash, Hari Hara; Bithal, Parmod Kumar; Chandra, P Sarat

2015-01-01

Background and Aims: The anaesthetic challenge of awake craniotomy is to maintain adequate sedation, analgesia, respiratory and haemodynamic stability in an awake patient who should be able to co-operate during intraoperative neurological assessment. The current literature, sharing the experience on awake craniotomy, in Indian context, is minimal. Hence, we carried out a retrospective study with the aim to review and analyse the anaesthetic management and perioperative complications in patients undergoing awake craniotomy, at our centre. Methods: Medical records of 54 patients who underwent awake craniotomy for intracranial lesions over a period of 10 years were reviewed, retrospectively. Data regarding anaesthetic management, intraoperative complications and post-operative course were recorded. Results: Propofol (81.5%) and dexmedetomidine (18.5%) were the main agents used for providing conscious sedation to facilitate awake craniotomy. Hypertension (16.7%) was the most commonly encountered complication during intraoperative period, followed by seizures (9.3%), desaturation (7.4%), tight brain (7.4%), and shivering (5.6%). The procedure had to be converted to general anaesthesia in one of patients owing to refractory brain bulge. The incidence of respiratory and haemodynamic complications were comparable in the both groups (P > 0.05). There was less incidence of intraoperative seizures in patients who received propofol (P = 0.03). In post-operative period, 20% of patients developed new motor deficit. Mean intensive care unit stay was 2.8 ± 1.9 day (1–14 days) and mean hospital stay was 7.0 ± 5.0 day (3–30 days). Conclusions: ‘Conscious sedation’ was the technique of choice for awake craniotomy, at our institute. Fentanyl, propofol, and dexmedetomidine were the main agents used for this purpose. Patients receiving propofol had less incidence of intraoperative seizure. Appropriate selection of patients, understanding the procedure of surgery, and judicious use of sedatives or anaesthetic agents are key to the success for awake craniotomy as a procedure. PMID:26019355

Risk of brain herniation after craniotomy with lumbar spinal drainage: a propensity score analysis.

PubMed

Motoyama, Yasushi; Nakajima, Tsukasa; Takamura, Yoshiaki; Nakazawa, Tsutomu; Wajima, Daisuke; Takeshima, Yasuhiro; Matsuda, Ryosuke; Tamura, Kentaro; Yamada, Shuichi; Yokota, Hiroshi; Nakagawa, Ichiro; Nishimura, Fumihiko; Park, Young-Su; Nakamura, Mitsutoshi; Nakase, Hiroyuki

2018-06-08

OBJECTIVE Lumbar spinal drainage (LSD) during neurosurgery can have an important effect by facilitating a smooth procedure when needed. However, LSD is quite invasive, and the pathology of brain herniation associated with LSD has become known recently. The objective of this study was to determine the risk of postoperative brain herniation after craniotomy with LSD in neurosurgery overall. METHODS Included were 239 patients who underwent craniotomy with LSD for various types of neurological diseases between January 2007 and December 2016. The authors performed propensity score matching to establish a proper control group taken from among 1424 patients who underwent craniotomy and met the inclusion criteria during the same period. The incidences of postoperative brain herniation between the patients who underwent craniotomy with LSD (group A, n = 239) and the matched patients who underwent craniotomy without LSD (group B, n = 239) were compared. RESULTS Brain herniation was observed in 24 patients in group A and 8 patients in group B (OR 3.21, 95% CI 1.36-8.46, p = 0.005), but the rate of favorable outcomes was higher in group A (OR 1.79, 95% CI 1.18-2.76, p = 0.005). Of the 24 patients, 18 had uncal herniation, 5 had central herniation, and 1 had uncal and subfalcine herniation; 8 patients with other than subarachnoid hemorrhage were included. Significant differences in the rates of deep approach (OR 5.12, 95% CI 1.8-14.5, p = 0.002) and temporal craniotomy (OR 10.2, 95% CI 2.3-44.8, p = 0.002) were found between the 2 subgroups (those with and those without herniation) in group A. In 5 patients, brain herniation proceeded even after external decompression (ED). Cox regression analysis revealed that the risk of brain herniation related to LSD increased with ED (hazard ratio 3.326, 95% CI 1.491-7.422, p < 0.001). Among all 1424 patients, ED resulted in progression or deterioration of brain herniation more frequently in those who underwent LSD than it did in those who did not undergo LSD (OR 9.127, 95% CI 1.82-62.1, p = 0.004). CONCLUSIONS Brain herniation downward to the tentorial hiatus is more likely to occur after craniotomy with LSD than after craniotomy without LSD. Using a deep approach and craniotomy involving the temporal areas are risk factors for brain herniation related to LSD. Additional ED would aggravate brain herniation after LSD. The risk of brain herniation after placement of a lumbar spinal drain during neurosurgery must be considered even when LSD is essential.

The Air Force Critical Care Air Transport Team (CCATT): Using the Estimating Supplies Program (ESP) to Validate Clinical Requirements

DTIC Science & Technology

2005-04-05

categories are postsurgical cases, and represent thoracic, staged exploratory laparotomy, vascular/amputation, and craniotomy PCs for which surgical...Post Surgical Craniotomy J – Environmental Emergency E – Burns > 20% BSA K – Medical, Anaphylaxis/Asthma F – Class III and IV Hemorrhagic Shock...Amputation G – Crush/Blunt Injury K – Med, Anaphylaxis Asthma D – Post Surgical Craniotomy H – Head Injury

Spreading Depressions as Secondary Insults after Traumatic Injury to the Human Brain

DTIC Science & Technology

2012-09-01

earlier and larger craniotomies and better outcomes, despite being similar in initial injury characteristics compared to KCH patients. VCU patients also...enrolled patients with acute TBI who met the following inclusion criteria: clinical decision for craniotomy for lesion evacuation, de compression, or... craniotomies for evacuation of intracranial mass lesions or cerebral decompression, a median of 9·9 h (IQR 4·5–26·3) after trauma

The Air Force Mobile Forward Surgical Team (MFST): Using the Estimating Supplies Program to Validate Clinical Requirement

DTIC Science & Technology

2004-12-01

conducted in an abbreviated, staged manner, such as laparotomies, decompression craniotomies , vascular shunts, or amputations. The FRSS provides...Performed at MFST Abbreviated laparotomy 36.29 Vascular shunt/ligate 32.84 Amputation 12.32 Decompression craniotomy 8.98 Thoracotomy 6.35...Vascular shunt/ligations 6 33 Abbreviated laparotomy 4 22 Amputation 3 16 Decompression craniotomy 3 16 Thoracotomy 2 10 Other 3 Total 18 100

Closing the gap on Achilles tendon rupture: A cadaveric study quantifying the tendon apposition achieved with commonly used immobilisation practices.

PubMed

Collins, Ruaraidh; Sudlow, Alexis; Loizou, Constantinos; Loveday, David T; Smith, George

2018-04-01

The relative benefits of surgical and conservative treatment of Achilles tendon rupture are widely debated. With modern conservative management protocols, the re-rupture risk appears to fall to one similar to surgical repair with negligible loss of function. Conservative management typically employs a period of time in an equinus cast with sequential ankle dorsiflexion in a functional orthosis. The optimal duration of immobilisation and rate of dorsiflexion is unknown. We aimed to quantify the change in Achilles tendon approximation achieved in common immobilisation techniques to assist the design of rehabilitation protocols. Twelve fresh-frozen cadaveric specimens had 2.5cm of Achilles tendon excised. The gap between the tendon ends were measured via windowed full equinus casts and compared with functional boots with successively removed heel wedges. The greatest tendon apposition was achieved with the equinus cast. Each wedge removed decreased the reapproximation by approximately 5mm. This paper supports the early use of maximal equinus casting in early management of acute Achilles tendon ruptures. Copyright © 2017 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

Quantifying surgical access in eyebrow craniotomy with and without orbital bar removal: cadaver and surgical phantom studies.

PubMed

Zador, Zsolt; Coope, David J; Gnanalingham, Kanna; Lawton, Michael T

2014-04-01

Eyebrow craniotomy is a recently described minimally invasive approach for tackling primarily pathology of the anterior skull base. The removal of the orbital bar may further expand the surgical corridor of this exposure, but the extent of benefit is poorly quantified. We assessed the effect of orbital bar removal with regards to surgical access in the eyebrow craniotomy using classic morphometric measurements in cadaver heads. Using surgical phantoms and neuronavigation, we also measured the 'working volume', a new parameter for characterising the volume of surgical access in these approaches. Silicon injected cadaver heads (n = 5) were used for morphometric analysis of the eyebrow craniotomy with and without orbital bar removal. Working depths and 'working areas' of surgical access were measured as defined by key anatomical landmarks. The eyebrow craniotomy with or without orbital bar removal was also simulated using surgical phantoms (n = 3, 90-120 points per trial), calibrated against a frameless neuronavigation system. Working volume was derived from reference coordinates recorded along the anatomical borders of the eyebrow craniotomy using the "α-shape algorithm" in R statistics. In cadaver heads, eyebrow craniotomy with removal of the orbital bar reduced the working depth to the ipsilateral anterior clinoid process (42 ± 2 versus 33 ± 3 mm; p < 0.05), but the working areas as defined by deep neurovascular and bony landmarks was statistically unchanged (total working areas of 418 ± 80 cm(2) versus 334 ± 48 cm(2); p = 0.4). In surgical phantom studies, however, working-volume for the simulated eyebrow craniotomies was increased with orbital bar removal (16 ± 1 cm(3) versus 21 ± 1 cm(3); p < 0.01). In laboratory studies, orbital bar removal in eyebrow craniotomy provides a modest reduction in working depth and increase in the working volume. But this must be weighed up against the added morbidity of the procedure. Working volume, a newly developed parameter may provide a more meaningful endpoint for characterising the surgical access for different surgical approaches and it could be applied to other operative cases undertaken with frameless neuronavigation.

[Biphasic ceramic wedge and plate fixation with locked adjustable screws for open wedge tibial osteotomy].

PubMed

Lavallé, F; Pascal-Mousselard, H; Rouvillain, J L; Ribeyre, D; Delattre, O; Catonné, Y

2004-10-01

The aim of this radiological study was to evaluate the use of a biphasic ceramic wedge combined with plate fixation with locked adjustable screws for open wedge tibial osteotomy. Twenty-six consecutive patients (27 knees) underwent surgery between December 1999 and March 2002 to establish a normal lower-limb axis. The series included 6 women and 20 men, mean age 50 years (16 right knees and 11 left knees). Partial weight-bearing with crutches was allowed on day 1. A standard radiological assessment was performed on day 1, 90, and 360 (plain AP and lateral stance films of the knee). A pangonogram was performed before surgery and at day 360. Presence of a lateral metaphyseal space, development of peripheral cortical bridges, and osteointegration of the bone substitute-bone interface were evaluated used to assess bone healing. The medial tibial angle between the line tangent to the tibial plateau and the anatomic axis of the tibia (beta) was evaluated to assess preservation of postoperative correction. The HKA angle was determined. Three patients were lost to follow-up and 23 patients (24 knees) were retained for analysis. At last follow-up, presence of peripheral cortical bridges and complete filling of the lateral metaphyseal space demonstrated bone healing in all patients. Good quality osteointegration was achieved since 21 knees did not present an interface between the bone substitute and native bone (homogeneous transition zone). The beta angle was unchanged for 23 knees. A normal axis was observed in patients (16 knees) postoperatively. Use of a biphasic ceramic wedge in combination with plate fixation with locked adjustable screws is a reliable option for open wedge tibial osteotomy. The bone substitute fills the gap well. Tolerance and integration are optimal. Bone healing is achieved. Plate fixation with protected weight bearing appears to be a solid assembly, maintaining these corrections.

Complex interactions between diapirs and 4-D subduction driven mantle wedge circulation.

NASA Astrophysics Data System (ADS)

Sylvia, R. T.; Kincaid, C. R.

2015-12-01

Analogue laboratory experiments generate 4-D flow of mantle wedge fluid and capture the evolution of buoyant mesoscale diapirs. The mantle is modeled with viscous glucose syrup with an Arrhenius type temperature dependent viscosity. To characterize diapir evolution we experiment with a variety of fluids injected from multiple point sources. Diapirs interact with kinematically induced flow fields forced by subducting plate motions replicating a range of styles observed in dynamic subduction models (e.g., rollback, steepening, gaps). Data is collected using high definition timelapse photography and quantified using image velocimetry techniques. While many studies assume direct vertical connections between the volcanic arc and the deeper mantle source region, our experiments demonstrate the difficulty of creating near vertical conduits. Results highlight extreme curvature of diapir rise paths. Trench-normal deflection occurs as diapirs are advected downward away from the trench before ascending into wedge apex directed return flow. Trench parallel deflections up to 75% of trench length are seen in all cases, exacerbated by complex geometry and rollback motion. Interdiapir interaction is also important; upwellings with similar trajectory coalesce and rapidly accelerate. Moreover, we observe a new mode of interaction whereby recycled diapir material is drawn down along the slab surface and then initiates rapid fluid migration updip along the slab-wedge interface. Variability in trajectory and residence time leads to complex petrologic inferences. Material from disparate source regions can surface at the same location, mix in the wedge, or become fully entrained in creeping flow adding heterogeneity to the mantle. Active diapirism or any other vertical fluid flux mechanism employing rheological weakening lowers viscosity in the recycling mantle wedge affecting both solid and fluid flow characteristics. Many interesting and insightful results have been presented based upon 2-D, steady-state thermal and flow regimes. We reiterate the importance of 4-D time evolution in subduction models. Analogue experiments allow added feedbacks and complexity improving intuition and providing insight for further investigation.

Awake craniotomy, electrophysiologic mapping, and tumor resection with high-field intraoperative MRI.

PubMed

Parney, Ian F; Goerss, Stephan J; McGee, Kiaran; Huston, John; Perkins, William J; Meyer, Frederic B

2010-05-01

Awake craniotomy and electrophysiologic mapping (EPM) is an established technique to facilitate the resection of near eloquent cortex. Intraoperative magnetic resonance imaging (iMRI) is increasingly used to aid in the resection of intracranial lesions. Standard draping protocols in high-field iMRI units make awake craniotomies challenging, and only two groups have previously reported combined EPM and high-field iMRI. We present an illustrative case describing a simple technique for combining awake craniotomy and EPM with high-field iMRI. A movable platter is used to transfer the patient from the operating table to a transport trolley and into the adjacent MRI and still maintaining the patient's surgical position. This system allows excess drapes to be removed, facilitating awake craniotomy. A 57-year-old right-handed man presented with new onset seizures. Magnetic resonance imaging demonstrated a large left temporal mass. The patient underwent an awake, left frontotemporal craniotomy. The EPM demonstrated a single critical area for speech in his inferior frontal gyrus. After an initial tumor debulking, the scalp flap was loosely approximated, the wound was covered with additional drapes, and the excess surrounding drapes were trimmed. An iMRI was obtained. The image-guidance system was re-registered and the patient was redraped. Additional resection was performed, allowing extensive removal of what proved to be an anaplastic astrocytoma. The patient tolerated this well without any new neurological deficits. Standard protocols for positioning and draping in high-field iMRI units make awake craniotomies problematic. This straightforward technique for combined awake EPM and iMRI may facilitate safe removal of large lesions in eloquent cortex. Copyright © 2010 Elsevier Inc. All rights reserved.

Spreading Depolarizations of Cerebral Cortex After Brain Injury: Mechanism of Injury Progression and Relevance to Military Neurotrauma

DTIC Science & Technology

2006-11-01

sustained penetrating brain injury (PBI). Emergency craniotomies are performed to treat these severe injuries in theater, sometimes on a daily...after craniotomy surgery. ECoG recordings were made subsequently for 1-10 days. CSD was identified by rapidly developing depression of ECoG amplitude...treat patients with moderate-to-severe TBI provides the opportunity to monitor for CSD by ECoG recordings. In these cases, craniotomy is performed as

Emergency Interventions After Severe Traumatic Brain Injury in Rats: Effect on Neuropathology and Functional Outcome

DTIC Science & Technology

2000-01-01

placed in a stereotaxic frame and a left parietal craniotomy was performed. The dura and bone flap were left in place until immediately before CCI. A...microtransducer) was inserted through a burr hole in the frontal bone into the contralateral (right) frontal cortex at the time of craniotomy ...immediately after injury) or vehicle. A separate sham group (all surgery including craniotomy , but no TBI was also studied. Brain temperature maintained at

Total Intravenous Anesthesia Including Ketamine versus Volatile Gas Anesthesia for Combat-related Operative Traumatic Brain Injury

DTIC Science & Technology

2008-07-01

receiving VGA with regard to Injury Severity Score, Glasgow Coma Scale score, base deficit, Head Abbreviated Injury Score, and craniectomy or craniotomy ...1, 2, or 3. Craniectomy or craniotomy was performed at the discretion of the neurosurgeon based on type of skull injury, severity of injury, and...perfectly on GCS ( 8, 8), base deficit ( 6, 6), Head Abbreviated Injury Score ( 3, 3) and craniectomy versus craniotomy . From these, subsets

Accuracy of frame-based stereotactic depth electrode implantation during craniotomy for subdural grid placement.

PubMed

Munyon, Charles N; Koubeissi, Mohamad Z; Syed, Tanvir U; Lüders, Hans O; Miller, Jonathan P

2013-01-01

Frame-based stereotaxy and open craniotomy may seem mutually exclusive, but invasive electrophysiological monitoring can require broad sampling of the cortex and precise targeting of deeper structures. The purpose of this study is to describe simultaneous frame-based insertion of depth electrodes and craniotomy for placement of subdural grids through a single surgical field and to determine the accuracy of depth electrodes placed using this technique. A total of 6 patients with intractable epilepsy underwent placement of a stereotactic frame with the center of the planned cranial flap equidistant from the fixation posts. After volumetric imaging, craniotomy for placement of subdural grids was performed. Depth electrodes were placed using frame-based stereotaxy. Postoperative CT determined the accuracy of electrode placement. A total of 31 depth electrodes were placed. Mean distance of distal electrode contact from the target was 1.0 ± 0.15 mm. Error was correlated to distance to target, with an additional 0.35 mm error for each centimeter (r = 0.635, p < 0.001); when corrected, there was no difference in accuracy based on target structure or method of placement (prior to craniotomy vs. through grid, p = 0.23). The described technique for craniotomy through a stereotactic frame allows placement of subdural grids and depth electrodes without sacrificing the accuracy of a frame or requiring staged procedures.

The floating anchored craniotomy

PubMed Central

Gutman, Matthew J.; How, Elena; Withers, Teresa

2017-01-01

Background: The “floating anchored” craniotomy is a technique utilized at our tertiary neurosurgery institution in which a traditional decompressive craniectomy has been substituted for a floating craniotomy. The hypothesized advantages of this technique include adequate decompression, reduction in the intracranial pressure, obviating the need for a secondary cranioplasty, maintained bone protection, preventing the syndrome of the trephined, and a potential reduction in axonal stretching. Methods: The bone plate is re-attached via multiple loosely affixed vicryl sutures, enabling decompression, but then ensuring the bone returns to its anatomical position once cerebral edema has subsided. Results: From the analysis of 57 consecutive patients analyzed at our institution, we have found that the floating anchored craniotomy is comparable to decompressive craniectomy for intracranial pressure reduction and has some significant theoretical advantages. Conclusions: Despite the potential advantages of techniques that avoid the need for a second cranioplasty, they have not been widely adopted and have been omitted from trials examining the utility of decompressive surgery. This retrospective analysis of prospectively collected data suggests that the floating anchored craniotomy may be applicable instead of decompressive craniectomy. PMID:28713633

The legacy of Hephaestus: the first craniotomy.

PubMed

Brasiliense, Leonardo Bc; Safavi-Abbasi, Sam; Crawford, Neil R; Spetzler, Robert F; Theodore, Nicholas

2010-10-01

Hephaestus is best known as the Greek god of metalworking, fire, and fine arts. As the only Olympian deity not endowed with physical perfection, he has been considered misfortunate among the Olympians. However, textual analysis of his myths reveals that Hephaestus was highly regarded by Greeks for his manual skills and intelligence. Furthermore, one of the myths about Hephaestus indicates that he performed the first recorded craniotomy. This text asserts that Hephaestus intentionally performed the craniotomy to remove a mass growing inside Zeus' head, thereby relieving him of an excruciating headache. The successful craniotomy resulted in the birth of the goddess Athena. From a neurosurgical perspective, the story is allegorical. Nonetheless, it represents the surgical management of intracranial ailments, which is thought to have been reported in Greece centuries later by Hippocrates.

Open wedge high tibial osteotomy using three-dimensional printed models: Experimental analysis using porcine bone.

PubMed

Kwun, Jun-Dae; Kim, Hee-June; Park, Jaeyoung; Park, Il-Hyung; Kyung, Hee-Soo

2017-01-01

The purpose of this study was to evaluate the usefulness of three-dimensional (3D) printed models for open wedge high tibial osteotomy (HTO) in porcine bone. Computed tomography (CT) images were obtained from 10 porcine knees and 3D imaging was planned using the 3D-Slicer program. The osteotomy line was drawn from the three centimeters below the medial tibial plateau to the proximal end of the fibular head. Then the osteotomy gap was opened until the mechanical axis line was 62.5% from the medial border along the width of the tibial plateau, maintaining the posterior tibial slope angle. The wedge-shaped 3D-printed model was designed with the measured angle and osteotomy section and was produced by the 3D printer. The open wedge HTO surgery was reproduced in porcine bone using the 3D-printed model and the osteotomy site was fixed with a plate. Accuracy of osteotomy and posterior tibial slope was evaluated after the osteotomy. The mean mechanical axis line on the tibial plateau was 61.8±1.5% from the medial tibia. There was no statistically significant difference (P=0.160). The planned and post-osteotomy correction wedge angles were 11.5±3.2° and 11.4±3.3°, and the posterior tibial slope angle was 11.2±2.2° pre-osteotomy and 11.4±2.5° post-osteotomy. There were no significant differences (P=0.854 and P=0.429, respectively). This study showed that good results could be obtained in high tibial osteotomy by using 3D printed models of porcine legs. Copyright © 2016 Elsevier B.V. All rights reserved.

[Stability, bone healing and loss of correction after valgus realignment of the tibial head. A roentgen stereometry analysis].

PubMed

Pape, D; Adam, F; Rupp, S; Seil, R; Kohn, D

2004-02-01

In high tibial closing-wedge osteotomies (HTO), closure of an osteotomy gap after resection of a bony wedge can be associated with a fissure of the medial cortex of the tibial head (MCT). The effect of a broken MCT on the recurrence of varus deformity is disputed. In this study, serial roentgen stereometric analysis (RSA) was used to determine the fixation stability of a rigid internal "L" plate after HTO. Full weight lower limb radiographs were used to determine the sagittal alignment in patients with varying degrees of varus malalignment and correction over time. Forty-two patients with varus gonarthrosis stage I-III (Ahlback) were treated with HTO and internal fixation with an L-shaped rigid plate. Patients were followed by serial RSA, conventional radiographs, and clinical evaluation (Hospital of Special Surgery score) over a 12-month period. In 19 of 42 successive patients, an average wedge size of 6.9 degrees was resected leaving the MCT intact (group 1). In 23 of 42 of patients, the MCT was unintentionally fissured during surgery when an average 10.3 degrees -wedge was resected (group 2). In group 2, RSA revealed a fivefold increase in lateral displacement of the distal tibial segment within 3 weeks after HTO. Twelve weeks after HTO, translations between tibial segments were below the accuracy of the RSA setup in the majority of patients. Group 1 patients demonstrated a higher initial fixation stability, less occurrence of varus deformity, and a higher HSS score compared to patients with larger wedge sizes and frequent fracture of the MCT (group 2). Before bone healing is achieved, the integrity of the MCT plays a crucial role for the clinical and radiological outcome after HTO.

[Awake craniotomy].

PubMed

Kobyakov, G L; Lubnin, A Yu; Kulikov, A S; Gavrilov, A G; Goryaynov, S A; Poddubskiy, A A; Lodygina, K S

2016-01-01

Awake craniotomy is a neurosurgical intervention aimed at identifying and preserving the eloquent functional brain areas during resection of tumors located near the cortical and subcortical language centers. This article provides a review of the modern literature devoted to the issue. The anatomical rationale and data of preoperative functional neuroimaging, intraoperative electrophysiological monitoring, and neuropsychological tests as well as the strategy of active surgical intervention are presented. Awake craniotomy is a rapidly developing technique aimed at both preserving speech and motor functions and improving our knowledge in the field of speech psychophysiology.

Flurbiprofen and hypertension but not hydroxyethyl starch are associated with post-craniotomy intracranial haematoma requiring surgery.

PubMed

Jian, M; Li, X; Wang, A; Zhang, L; Han, R; Gelb, A W

2014-11-01

Post-craniotomy intracranial haematoma is one of the most serious complications after neurosurgery. We examined whether post-craniotomy intracranial haematoma requiring surgery is associated with the non-steroidal anti-inflammatory drugs flurbiprofen, hypertension, or hydroxyethyl starch (HES). A case-control study was conducted among 42 359 patients who underwent elective craniotomy procedures at Beijing Tiantan Hospital between January 2006 and December 2011. A one-to-one control group without post-craniotomy intracranial haematoma was selected matched by age, pathologic diagnosis, tumour location, and surgeon. Perioperative blood pressure records up to the diagnosis of haematoma, the use of flurbiprofen and HES were examined. The incidence of post-craniotomy intracranial haematoma and the odds ratios for the risk factors were determined. A total of 202 patients suffered post-craniotomy intracranial haematoma during the study period, for an incidence of 0.48% (95% CI=0.41-0.55). Haematoma requiring surgery was associated with an intraoperative systolic blood pressure of >160 mm Hg (OR=2.618, 95% CI=2.084-2.723, P=0.007), an intraoperative mean blood pressure of >110 mm Hg (OR=2.600, 95% CI=2.312-3.098, P=0.037), a postoperative systolic blood pressure of >160 mm Hg (OR=2.060, 95% CI= 1.763-2.642, P=0.022), a postoperative mean blood pressure of >110 mm Hg (OR=3.600, 95% CI= 3.226-4.057, P=0.001), and the use of flurbiprofen during but not after the surgery (OR=2.256, 95% CI=2.004-2.598, P=0.005). The intraoperative infusion of HES showed no significant difference between patients who had a haematoma and those who did not. Intraoperative and postoperative hypertension and the use of flurbiprofen during surgery are risk factors for post-craniotomy intracranial haematoma requiring surgery. The intraoperative infusion of HES was not associated with a higher incidence of haematoma. © The Author 2014. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Utilization of a Vehicle Integrated Intelligence (V(INT)2) System in Armor Units

DTIC Science & Technology

1984-04-01

weaknesses or deficiencies in the plan such as blind spots or fire integration plans likely to result in either overkill or underkill (e.g., gaps). The...movement is used with this formation. 108 A PL TI.I TK2 . *Thiso~ A oiiaini sdweee h Figue 5-4. CmbatWedg PLL PS I 10 M4w ;ok *Thi modificatio isue-heee-h

Surgical Evacuation of Spontaneous Supratentorial Lobar Intracerebral Hemorrhage: Comparison of Safety and Efficacy of Stereotactic Aspiration, Endoscopic Surgery, and Craniotomy.

PubMed

Li, Yuqian; Yang, Ruixin; Li, Zhihong; Yang, Yanping; Tian, Bo; Zhang, Xingye; Wang, Bao; Lu, Dan; Guo, Shaochun; Man, Minghao; Yang, Yang; Luo, Tao; Gao, Guodong; Li, Lihong

2017-09-01

The safety and efficacy of craniotomy, endoscopic surgery, and stereotactic aspiration for surgical evacuation of spontaneous supratentorial lobar intracerebral hemorrhage (ICH) is yet uncertain. The present study analyzed the clinical and radiographic data from 99 patients with spontaneous supratentorial lobar ICH, retrospectively, to address this issue. Patients who underwent craniotomy, endoscopy surgery, or stereotactic aspiration were assigned to the craniotomy group (n = 31), endoscopy surgery group (n = 32), or stereotactic aspiration group (n = 36), respectively. The characteristics of all the enrolled patients at the time of admission were assimilated. Also, the therapeutic effects of the three surgical procedures were evaluated based on short-term outcomes within 30 days and long-term outcomes at 6 months after the ictus. The results showed that stereotactic aspiration and endoscopic surgery were associated with a superior clinical therapeutic effect in both short-term and long-term outcomes than craniotomy for the treatment of spontaneous supratentorial lobar ICH. Notably, severely affected patients with hematoma volume > 60 mL or Glasgow Coma Scale score 4-8 may benefit more from endoscopic surgery than the two other surgical procedures. The current findings demonstrate that both stereotactic aspiration and endoscopic surgery possess an apparent advantage over craniotomy for the evacuation of spontaneous supratentorial lobar ICH. The endoscopic surgery might be more safe and effective with higher evacuation rate, better functional neurological outcomes, and lower complication and mortality rates. Copyright © 2017 Elsevier Inc. All rights reserved.

Pain during awake craniotomy for brain tumor resection. Incidence, causes, consequences and management.

PubMed

Fontaine, D; Almairac, F

2017-06-01

Awake craniotomy for brain tumor resection is usually well-tolerated and most of the patients are satisfied. However, in studies reporting the patients' postoperative perception of the awake craniotomy procedure, about half of them have experienced some degree of intraoperative pain. Pain was mild (intensity between 1 and 2 on the visual analogical score) short lasting in most cases, and did not challenge the procedure. Pain was reported as moderate in about 25% and exceptionally severe. We conducted a preliminary survey among French centers (n=9) routinely performing awake craniotomy. Neurosurgeons' opinions were concordant with patient's reports. Intraoperative pain exceptionally challenged the awake craniotomy procedure or led to changes in the resection strategy. For neurosurgeons, the most challenging causes of intraoperative pain were the patient's inadequate installation, the contact of surgical tools with pain-sensitive intracranial structures, especially the dura mater of the skull base, falx cerebri, and the leptomeninges of the lateral fissure and neighboring sulci. Strategies to deal with these causes included focusing the patient on the intraoperative functional tests to distract their attention away from the pain, and avoiding contacts with the pain-sensitive intracranial structures during the awake phase. Adequate preoperative patient information and preparation, trained anesthesiologists and application of recommendations for awake craniotomy procedures as well as adaptation of surgical technique to avoid contact with pain-sensitive intracranial structures are key factors to prevent intraoperative pain and ensure patient's postoperative satisfaction. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Asleep-awake-asleep craniotomy: a comparison with general anesthesia for resection of supratentorial tumors.

PubMed

Rajan, Shobana; Cata, Juan P; Nada, Eman; Weil, Robert; Pal, Rakhi; Avitsian, Rafi

2013-08-01

The anesthetic plan for patients undergoing awake craniotomy, when compared to craniotomy under general anesthesia, is different, in that it requires changes in states of consciousness during the procedure. This retrospective review compares patients undergoing an asleep-awake-asleep technique for craniotomy (group AW: n = 101) to patients undergoing craniotomy under general anesthesia (group AS: n = 77). Episodes of desaturation (AW = 31% versus AS = 1%, p < 0.0001), although temporary, and hypercarbia (AW = 43.75 mmHg versus AS = 32.75 mmHg, p < 0.001) were more common in the AW group. The mean arterial pressure during application of head clamp pins and emergence was significantly lower in AW patients compared to AS patients (pinning 91.47 mmHg versus 102.9 mmHg, p < 0.05 and emergence 84.85 mmHg versus 105 mmHg, p < 0.05). Patients in the AW group required less vasopressors intraoperatively (AW = 43% versus AS = 69%, p < 0.01). Intraoperative fluids were comparable between the two groups. The post anesthesia care unit (PACU) administered significantly fewer intravenous opioids in the AW group. The length of stay in the PACU and hospital was comparable in both groups. Thus, asleep-awake-asleep craniotomies with propofol-dexmedetomidine infusion had less hemodynamic response to pinning and emergence, and less overall narcotic use compared to general anesthesia. Despite a higher incidence of temporary episodes of desaturation and hypoventilation, no adverse clinical consequences were seen. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Fabry-Perot interferometric imaging spectrometer in LWIR

NASA Astrophysics Data System (ADS)

Zhang, Fang; Gao, Jiaobo; Wang, Nan; Wu, Jianghui; Meng, Hemin; Zhang, Lei; Gao, Shan

2017-02-01

With applications ranging from the desktop to remote sensing, the long wave infrared (LWIR) interferometric spectral imaging system is always with huge volume and large weight. In order to miniaturize and light the instrument, a new method of LWIR spectral imaging system based on a variable gap Fabry-Perot (FP) interferometer is researched. With the system working principle analyzed, theoretically, it is researched that how to make certain the primary parameter, such as, wedge angle of interferometric cavity, f-number of the imaging lens and the relationship between the wedge angle and the modulation of the interferogram. A prototype is developed and a good experimental result of a uniform radiation source, a monochromatic source, is obtained. The research shows that besides high throughput and high spectral resolution, the advantage of miniaturization is also simultaneously achieved in this method.

Awake craniotomy for assisting placement of auditory brainstem implant in NF2 patients.

PubMed

Zhou, Qiangyi; Yang, Zhijun; Wang, Zhenmin; Wang, Bo; Wang, Xingchao; Zhao, Chi; Zhang, Shun; Wu, Tao; Li, Peng; Li, Shiwei; Zhao, Fu; Liu, Pinan

2018-06-01

Auditory brainstem implants (ABIs) may be the only opportunity for patients with NF2 to regain some sense of hearing sensation. However, only a very small number of individuals achieved open-set speech understanding and high sentence scores. Suboptimal placement of the ABI electrode array over the cochlear nucleus may be one of main factors for poor auditory performance. In the current study, we present a method of awake craniotomy to assist with ABI placement. Awake surgery and hearing test via the retrosigmoid approach were performed for vestibular schwannoma resections and auditory brainstem implantations in four patients with NF2. Auditory outcomes and complications were assessed postoperatively. Three of 4 patients who underwent awake craniotomy during ABI surgery received reproducible auditory sensations intraoperatively. Satisfactory numbers of effective electrodes, threshold levels and distinct pitches were achieved in the wake-up hearing test. In addition, relatively few electrodes produced non-auditory percepts. There was no serious complication attributable to the ABI or awake craniotomy. It is safe and well tolerated for neurofibromatosis type 2 (NF2) patients using awake craniotomy during auditory brainstem implantation. This method can potentially improve the localization accuracy of the cochlear nucleus during surgery.

Reconciling Air Force Physicians’ Peacetime and Wartime Capabilities, Demonstration of a Work Force Design Methodology.

DTIC Science & Technology

1985-08-01

training would again be required, include work on peripheral nerves, craniotomy and craniectomy (although approximately one-fifth of the -general surgeons...said never to craniotomy and craniectomy), and closed and open reductions of fractures of facial bones. Surgical subspecialty examinations can be...0 0 0 0 0 0 Free skin grfts-sites exc face 100 0 0 0 0 0 0 Free skin grafts to face 81 16 4 0 0 0 0 Craniotomy /craniectomy 7 25 11 12 11 15 19 Burr

Burr Hole Washout versus Craniotomy for Chronic Subdural Hematoma: Patient Outcome and Cost Analysis

PubMed Central

Regan, Jacqueline M.; Worley, Emmagene; Shelburne, Christopher; Pullarkat, Ranjit; Watson, Joseph C.

2015-01-01

Chronic subdural hematomas (CSDH), which are frequently encountered in neurosurgical practice, are, in the majority of cases, ideally treated with surgical drainage. Despite this common practice, there is still controversy surrounding the best surgical procedure. With lack of clear evidence of a superior technique, surgeons are free to base the decision on other factors that are not related to patient care. A retrospective chart review of 119 patients requiring surgical drainage of CSDH was conducted at a large tertiary care center over a three-year period. Of the cases reviewed, 58 patients underwent craniotomy, while 61 patients underwent burr hole washout. The study focused on re-operation rates, mortality, and morbidity, as measured by Glasgow coma scores (GCS), discharge Rankin disability scores, and discharge disposition. Secondary endpoints included length of stay and cost of procedure. Burr hole washout was superior to craniotomy with respect to patient outcome, length of stay and recurrence rates. In both study groups, patients required additional surgical procedures (6.6% of burr hole patients and 24.1% of craniotomy patients) (P = 0.0156). Of the patients treated with craniotomy, 51.7% were discharged home, whereas 65.6% of the burr hole patients were discharged home. Patients who underwent burr hole washout spent a mean of 78.8 minutes in the operating suite while the patients undergoing craniotomy spent 129.4 minutes (P < 0.001). The difference in mean cost per patient, based solely on operating time, was $2,828 (P < 0.001). This does not include the further cost due to additional procedures and hospital stay. The mean length of stay after surgical intervention was 3 days longer for the craniotomy group (P = 0.0465). Based on this retrospective study, burr hole washout is superior for both patients’ clinical and financial outcome; however, prospective long-term multicenter clinical studies are required to verify these findings. PMID:25611468

Burr hole washout versus craniotomy for chronic subdural hematoma: patient outcome and cost analysis.

PubMed

Regan, Jacqueline M; Worley, Emmagene; Shelburne, Christopher; Pullarkat, Ranjit; Watson, Joseph C

2015-01-01

Chronic subdural hematomas (CSDH), which are frequently encountered in neurosurgical practice, are, in the majority of cases, ideally treated with surgical drainage. Despite this common practice, there is still controversy surrounding the best surgical procedure. With lack of clear evidence of a superior technique, surgeons are free to base the decision on other factors that are not related to patient care. A retrospective chart review of 119 patients requiring surgical drainage of CSDH was conducted at a large tertiary care center over a three-year period. Of the cases reviewed, 58 patients underwent craniotomy, while 61 patients underwent burr hole washout. The study focused on re-operation rates, mortality, and morbidity, as measured by Glasgow coma scores (GCS), discharge Rankin disability scores, and discharge disposition. Secondary endpoints included length of stay and cost of procedure. Burr hole washout was superior to craniotomy with respect to patient outcome, length of stay and recurrence rates. In both study groups, patients required additional surgical procedures (6.6% of burr hole patients and 24.1% of craniotomy patients) (P = 0.0156). Of the patients treated with craniotomy, 51.7% were discharged home, whereas 65.6% of the burr hole patients were discharged home. Patients who underwent burr hole washout spent a mean of 78.8 minutes in the operating suite while the patients undergoing craniotomy spent 129.4 minutes (P < 0.001). The difference in mean cost per patient, based solely on operating time, was $2,828 (P < 0.001). This does not include the further cost due to additional procedures and hospital stay. The mean length of stay after surgical intervention was 3 days longer for the craniotomy group (P = 0.0465). Based on this retrospective study, burr hole washout is superior for both patients' clinical and financial outcome; however, prospective long-term multicenter clinical studies are required to verify these findings.

Efficacy and safety of dexmedetomidine infusion for patients undergoing awake craniotomy: An observational study.

PubMed

Mahajan, Charu; Rath, Girija Prasad; Singh, Gyaninder Pal; Mishra, Nitasha; Sokhal, Suman; Bithal, Parmod Kumar

2018-01-01

The goal of awake craniotomy is to maintain adequate sedation, analgesia, respiratory, and hemodynamic stability and also to provide a cooperative patient for neurologic testing. An observational study carried out to evaluate the efficacy of dexmedetomidine sedation for awake craniotomy. Adult patients with age >18 year who underwent awake craniotomy for intracranial tumor surgery were enrolled. Those who were uncooperative and had difficult airway were excluded from the study. In the operating room, the patients received a bolus dose of dexmedetomidine 1 μg/kg followed by an infusion of 0.2-0.7 μg/kg/h (bispectral index target 60-80). Once the patients were sedated, scalp block was given with bupivacaine 0.25%. The data on hemodynamics at various stages of the procedure, intraoperative complications, total amount of fentanyl used, intravenous fluids required, blood loss and transfusion, duration of surgery, Intensive Care Unit (ICU), and hospital stay were collected. The patients were assessed for Glasgow outcome scale (GOS) score and patient satisfaction score (PSS). A total of 27 patients underwent awake craniotomy during a period of 2 years. Most common intraoperative complication was seizures; observed in five patients (18.5%). None of these patients experienced any episode of desaturation. Two patients had tight brain for which propofol boluses were administered. The average fentanyl consumption was 161.5 ± 85.0 μg. The duration of surgery, ICU, and hospital stays were 231.5 ± 90.5 min, 14.5 ± 3.5 h, and 4.7 ± 1.5 days, respectively. The overall PSS was 8 and GOS was good in all the patients. The use of dexmedetomidine infusion with regional scalp block in patients undergoing awake craniotomy is safe and efficacious. The absence of major complications and higher PSS makes it close to an ideal agent for craniotomy in awake state.

Efficacy and safety of dexmedetomidine infusion for patients undergoing awake craniotomy: An observational study

PubMed Central

Mahajan, Charu; Rath, Girija Prasad; Singh, Gyaninder Pal; Mishra, Nitasha; Sokhal, Suman; Bithal, Parmod Kumar

2018-01-01

Background: The goal of awake craniotomy is to maintain adequate sedation, analgesia, respiratory, and hemodynamic stability and also to provide a cooperative patient for neurologic testing. An observational study carried out to evaluate the efficacy of dexmedetomidine sedation for awake craniotomy. Materials and Methods: Adult patients with age >18 year who underwent awake craniotomy for intracranial tumor surgery were enrolled. Those who were uncooperative and had difficult airway were excluded from the study. In the operating room, the patients received a bolus dose of dexmedetomidine 1 μg/kg followed by an infusion of 0.2–0.7 μg/kg/h (bispectral index target 60–80). Once the patients were sedated, scalp block was given with bupivacaine 0.25%. The data on hemodynamics at various stages of the procedure, intraoperative complications, total amount of fentanyl used, intravenous fluids required, blood loss and transfusion, duration of surgery, Intensive Care Unit (ICU), and hospital stay were collected. The patients were assessed for Glasgow outcome scale (GOS) score and patient satisfaction score (PSS). Results: A total of 27 patients underwent awake craniotomy during a period of 2 years. Most common intraoperative complication was seizures; observed in five patients (18.5%). None of these patients experienced any episode of desaturation. Two patients had tight brain for which propofol boluses were administered. The average fentanyl consumption was 161.5 ± 85.0 μg. The duration of surgery, ICU, and hospital stays were 231.5 ± 90.5 min, 14.5 ± 3.5 h, and 4.7 ± 1.5 days, respectively. The overall PSS was 8 and GOS was good in all the patients. Conclusion: The use of dexmedetomidine infusion with regional scalp block in patients undergoing awake craniotomy is safe and efficacious. The absence of major complications and higher PSS makes it close to an ideal agent for craniotomy in awake state. PMID:29628833

Incidence of Postoperative Hematomas Requiring Surgical Treatment in Neurosurgery: A Retrospective Observational Study.

PubMed

Lillemäe, Kadri; Järviö, Johanna Annika; Silvasti-Lundell, Marja Kaarina; Antinheimo, Jussi Juha-Pekka; Hernesniemi, Juha Antero; Niemi, Tomi Tapio

2017-12-01

We aimed to characterize the occurrence of postoperative hematoma (POH) after neurosurgery overall and according to procedure type and describe the prevalence of possible confounders. Patient data between 2010 and 2012 at the Department of Neurosurgery in Helsinki University Hospital were retrospectively analyzed. A data search was performed according to the type of surgery including craniotomies; shunt procedures, spine surgery, and spinal cord stimulator implantation. We analyzed basic preoperative characteristics, as well as data about the initial intervention, perioperative period, revision operation and neurologic recovery (after craniotomy only). The overall incidence of POH requiring reoperation was 0.6% (n = 56/8783) to 0.6% (n = 26/4726) after craniotomy, 0% (n = 0/928) after shunting procedure, 1.1% (n = 30/2870) after spine surgery, and 0% (n = 0/259) after implantation of a spinal cord stimulator. Craniotomy types with higher POH incidence were decompressive craniectomy (7.9%, n = 7/89), cranioplasty (3.6%, n = 4/112), bypass surgery (1.7%, n = 1/60), and epidural hematoma evacuation (1.6%, n = 1/64). After spinal surgery, POH was observed in 1.1% of cervical and 2.1% of thoracolumbar operations, whereas 46.7% were multilevel procedures. 64.3% of patients with POH and 84.6% of patients undergoing craniotomy had postoperative hypertension (systolic blood pressure >160 mm Hg or lower if indicated). Poor outcome (Glasgow Outcome Scale score 1-3), whereas death at 6 months after craniotomy was detected in 40.9% and 21.7%. respectively, of patients with POH who underwent craniotomy. POH after neurosurgery was rare in this series but was associated with poor outcome. Identification of risk factors of bleeding, and avoiding them, if possible, might decrease the incidence of POH. Copyright © 2017 Elsevier Inc. All rights reserved.

Anesthetic management with scalp nerve block and propofol/remifentanil infusion during awake craniotomy in an adolescent patient -A case report-

PubMed Central

Sung, Bohyun; Park, Jin-Woo; Byon, Hyo-Jin; Kim, Jin-Tae; Kim, Chong Sung

2010-01-01

Despite of various neurophysiologic monitoring methods under general anesthesia, functional mapping at awake state during brain surgery is helpful for conservation of speech and motor function. But, awake craniotomy in children or adolescents is worrisome considering their emotional friabilities. We present our experience on anesthetic management for awake craniotomy in an adolescent patient. The patient was 16 years old male who would undergo awake craniotomy for removal of brain tumor. Scalp nerve block was done with local anesthetics and we infused propofol and remifentanil with target controlled infusion. The patient endured well and was cooperative before scalp suture, but when surgeon sutured scalp, he complained of pain and was suddenly agitated. We decided change to general anesthesia. Neurosurgeon did full neurologic examinations and there was no neurologic deficit except facial palsy of right side. Facial palsy had improved with time. PMID:21286435

[AWAKE CRANIOTOMY: IN SEARCH FOR OPTIMAL SEDATION].

PubMed

Kulikova, A S; Sel'kov, D A; Kobyakov, G L; Shmigel'skiy, A V; Lubnin, A Yu

2015-01-01

Awake craniotomy is a "gold standard"for intraoperative brain language mapping. One of the main anesthetic challenge of awake craniotomy is providing of optimal sedation for initial stages of intervention. The goal of this study was comparison of different technics of anesthesia for awake craniotomy. Materials and methods: 162 operations were divided in 4 groups: 76 cases with propofol sedation (2-4mg/kg/h) without airway protection; 11 cases with propofol sedation (4-5 mg/kg/h) with MV via LMA; 36 cases of xenon anesthesia; and 39 cases with dexmedetomidine sedation without airway protection. Results and discussion: brain language mapping was successful in 90% of cases. There was no difference between groups in successfulness of brain mapping. However in the first group respiratory complications were more frequent. Three other technics were more safer Xenon anesthesia was associated with ultrafast awakening for mapping (5±1 min). Dexmedetomidine sedation provided high hemodynamic and respiratory stability during the procedure.

Resting state functional connectivity magnetic resonance imaging integrated with intraoperative neuronavigation for functional mapping after aborted awake craniotomy

PubMed Central

Batra, Prag; Bandt, S. Kathleen; Leuthardt, Eric C.

2016-01-01

Background: Awake craniotomy is currently the gold standard for aggressive tumor resections in eloquent cortex. However, a significant subset of patients is unable to tolerate this procedure, particularly the very young or old or those with psychiatric comorbidities, cardiopulmonary comorbidities, or obesity, among other conditions. In these cases, typical alternative procedures include biopsy alone or subtotal resection, both of which are associated with diminished surgical outcomes. Case Description: Here, we report the successful use of a preoperatively obtained resting state functional connectivity magnetic resonance imaging (MRI) integrated with intraoperative neuronavigation software in order to perform functional cortical mapping in the setting of an aborted awake craniotomy due to loss of airway. Conclusion: Resting state functional connectivity MRI integrated with intraoperative neuronavigation software can provide an alternative option for functional cortical mapping in the setting of an aborted awake craniotomy. PMID:26958419

Use of Subdural Evacuating Port System Following Open Craniotomy with Excision of Native Dura and Membranes for Management of Chronic Subdural Hematoma.

PubMed

Cage, Tene; Bach, Ashley; McDermott, Michael W

2017-04-26

An 86-year-old woman was admitted to the intensive care unit with a chronic subdural hematoma (CSDH) and rapid onset of worsening neurological symptoms. She was taken to the operating room for a mini-craniotomy for evacuation of the CSDH including excision of the dura and CSDH membrane. Postoperatively, a subdural evacuation port system (SEPS) was integrated into the craniotomy site and left in place rather than a traditional subdural catheter drain to evacuate the subdural space postoperatively. The patient had a good recovery and improvement of symptoms after evacuation and remained clinically well after the SEPS was removed. We offer the technique of dura and CSDH membrane excision plus SEPS drain as an effective postoperative alternative to the standard craniotomy leaving the native dura intact with traditional subdural drain that overlies the cortical surface of the brain in treating patients with CSDH.

Perioperative Factors Contributing the Post-Craniotomy Pain: A Synthesis of Concepts.

PubMed

Chowdhury, Tumul; Garg, Rakesh; Sheshadri, Veena; Venkatraghavan, Lakshmi; Bergese, Sergio Daniel; Cappellani, Ronald B; Schaller, Bernhard

2017-01-01

The perioperative management of post-craniotomy pain is controversial. Although the concept of pain control in non-neurosurgical fields has grown substantially, the understanding of neurosurgical pain and its causative factors in such a population is inconclusive. In fact, the organ that is the center of pain and its related mechanisms receives little attention to alleviate distress during neurosurgical procedures. In contrast to the old belief that pain following intracranial surgery is minimal, recent data suggest the exact opposite. Despite the evolution of various multimodal analgesic techniques for optimal pain control, the concern of post-craniotomy pain remains. This paradox could be due to the lack of thorough understanding of different perioperative factors that can influence the incidence and intensity of pain in post-craniotomy population. Therefore, this review aims to give an in-depth insight into the various aspects of pain and its related factors in adult neurosurgical patients.

Perioperative Factors Contributing the Post-Craniotomy Pain: A Synthesis of Concepts

PubMed Central

Chowdhury, Tumul; Garg, Rakesh; Sheshadri, Veena; Venkatraghavan, Lakshmi; Bergese, Sergio Daniel; Cappellani, Ronald B.; Schaller, Bernhard

2017-01-01

The perioperative management of post-craniotomy pain is controversial. Although the concept of pain control in non-neurosurgical fields has grown substantially, the understanding of neurosurgical pain and its causative factors in such a population is inconclusive. In fact, the organ that is the center of pain and its related mechanisms receives little attention to alleviate distress during neurosurgical procedures. In contrast to the old belief that pain following intracranial surgery is minimal, recent data suggest the exact opposite. Despite the evolution of various multimodal analgesic techniques for optimal pain control, the concern of post-craniotomy pain remains. This paradox could be due to the lack of thorough understanding of different perioperative factors that can influence the incidence and intensity of pain in post-craniotomy population. Therefore, this review aims to give an in-depth insight into the various aspects of pain and its related factors in adult neurosurgical patients. PMID:28299313

Keyhole concept in cerebral aneurysm clipping and tumor removal by the supraciliary lateral supraorbital approach

PubMed Central

Mori, Kentaro

2014-01-01

The keyhole concept in neurosurgery is designed to minimize the craniotomy needed for the access route to deep intracranial pathologies. Such keyhole surgeries cause less trauma and can be less invasive than conventional surgical techniques. Among the various types of keyhole mini-craniotomy, supraorbital or lateral supraorbital mini-craniotomy is the standard and basic keyhole approaches. The lateral supraorbital keyhole provides adequate working space in the suprasellar to parasellar areas and planum sphenoidale area including the anterior communicating artery complex. Despite the development of neuro-endoscopic techniques and intra-operative assistant methods, the limited working angle to manipulate and observe deeply situated pathologies is a major disadvantage of the keyhole approaches. Neurosurgeons should understand that keyhole mini-craniotomy surgeries aim at “minimally invasive neurosurgery” but still carry the risks of malpractice unless we understand the advantages and disadvantages of these keyhole concepts and strategies. PMID:24891885

Advances in open microsurgery for cerebral aneurysms.

PubMed

Davies, Jason M; Lawton, Michael T

2014-02-01

Endovascular techniques introduced strong extrinsic forces that provoked reactive changes in aneurysm surgery. Microsurgery has become less invasive, more appealing to patients, lower risk, and efficacious for complex aneurysms, particularly those unfavorable for or failing endovascular therapy. To review specific advances in open microsurgery for aneurysms. A university-based, single-surgeon practice was examined for the use of minimally invasive craniotomies, surgical management of recurrence after coiling, the use of intracranial-intracranial bypass techniques, and cerebrovascular volume-outcome relationships. The mini-pterional, lateral supraorbital, and orbital-pterional craniotomies are minimally invasive alternatives to standard craniotomies. Mini-pterional and lateral supraorbital craniotomies were used in one-fourth of unruptured patients, increasing from 22% to 28%, whereas 15% of patients underwent orbital-pterional craniotomies and trended upward from 11% to 20%. Seventy-four patients were treated for coil recurrences (2.3% of all aneurysms) with direct clip occlusion (77%), clip occlusion after coil extraction (7%), or parent artery occlusion with bypass (16%). Intracranial-intracranial bypass (in situ bypass, reimplantation, reanastomosis, and intracranial grafts) transformed the management of giant aneurysms and made the surgical treatment of posterior inferior cerebellar artery aneurysms competitive with endovascular therapy. Centralization maximized the volume-outcome relationships observed with clipping. Aneurysm microsurgery has embraced minimalism, tailoring the exposure to the patient's anatomy with the smallest possible craniotomy that provides adequate exposure. The development of intracranial-intracranial bypasses is an important advancement that makes microsurgery a competitive option for complex and recurrent aneurysms. Trends toward centralizing aneurysm surgery in tertiary centers optimize results achievable with open microsurgery.

Anesthetic approach to high-risk patients and prolonged awake craniotomy using dexmedetomidine and scalp block.

PubMed

Garavaglia, Marco M; Das, Sunit; Cusimano, Michael D; Crescini, Charmagne; Mazer, C David; Hare, Gregory M T; Rigamonti, Andrea

2014-07-01

Awake craniotomy with intraoperative speech or motor testing is relatively contraindicated in cases requiring prolonged operative times and in patients with severe medical comorbidities including anxiety, anticipated difficult airway, obesity, large tumors, and intracranial hypertension. The anesthetic management of neurosurgical patients who possess these contraindications but would be optimally treated by an awake procedure remains unclear. We describe a new anesthetic approach for awake craniotomy that did not require any airway manipulation, utilizing a bupivacaine-based scalp nerve block, and dexmedetomidine as the primary hypnotic-sedative agent. Using this technique, we provided optimal operative conditions to perform awake craniotomy facilitating safe tumor resection, while utilizing intraoperative electrocorticography for motor and speech mapping in a cohort of 10 patients at a high risk for airway compromise and complications associated with patient comorbidities. All patients underwent successful awake craniotomy, intraoperative mapping, and tumor resection with adequate sedation for up to 9 hours (median 3.5 h, range 3 to 9 h) without any loss of neurological function, airway competency, or the need to provide any active rescue airway management. We report 4 of these cases that highlight our experience: 1 case required prolonged surgery because of the complexity of tumor resection and 3 patients had important medical comorbidities and/or relative contraindication for an awake procedure. Dexmedetomidine, with concurrent scalp block, is an effective and safe anesthetic approach for awake craniotomy. Dexmedetomidine facilitates the extension procedure complexity and duration in patients who might traditionally not be considered to be candidates for this procedure.

Prospective study of awake craniotomy used routinely and nonselectively for supratentorial tumors.

PubMed

Serletis, Demitre; Bernstein, Mark

2007-07-01

The authors prospectively assessed the value of awake craniotomy used nonselectively in patients undergoing resection of supratentorial tumors. The demographic features, presenting symptoms, tumor location, histological diagnosis, outcomes, and complications were documented for 610 patients who underwent awake craniotomy for supratentorial tumor resection. Intraoperative brain mapping was used in 511 cases (83.8%). Mapping identified eloquent cortex in 115 patients (22.5%) and no eloquent cortex in 396 patients (77.5%). Neurological deficits occurred in 89 patients (14.6%). In the subset of 511 patients in whom brain mapping was performed, 78 (15.3%) experienced postoperative neurological worsening. This phenomenon was more common in patients with preoperative neurological deficits or in those individuals in whom mapping successfully identified eloquent tissue. Twenty-five (4.9%) of the 511 patients suffered intraoperative seizures, and two of these individuals required intubation and induction of general anesthesia after generalized seizures occurred. Four (0.7%) of the 610 patients developed wound complications. Postoperative hematomas developed in seven patients (1.1%), four of whom urgently required a repeated craniotomy to allow evacuation of the clot. Two patients (0.3%) required readmission to the hospital soon after being discharged. There were three deaths (0.5%). Awake craniotomy is safe, practical, and effective during resection of supratentorial lesions of diverse pathological range and location. It allows for intraoperative brain mapping that helps identify and protect functional cortex. It also avoids the complications inherent in the induction of general anesthesia. Awake craniotomy provides an excellent alternative to surgery of supratentorial brain lesions in patients in whom general anesthesia has been induced.

Post-craniotomy intracranial infection in patients with brain tumors: a retrospective analysis of 5723 consecutive patients.

PubMed

Shi, Zhong-Hua; Xu, Ming; Wang, Yong-Zhi; Luo, Xu-Ying; Chen, Guang-Qiang; Wang, Xin; Wang, Tao; Tang, Ming-Zhong; Zhou, Jian-Xin

2017-02-01

To determine the risk factors for and the incidence, outcomes, and causative pathogens of post-craniotomy intracranial infection (PCII) in patients with brain tumors. A retrospective study was performed of 5723 patients with brain tumors who were surgically treated between January 2012 and December 2013 in Beijing Tiantan Hospital. The patients' demographics, pathohistological diagnoses, surgical procedures, postoperative variables, causative pathogens, and outcomes were evaluated. The overall incidence of PCII was 6.8%, and 82.1% of all cases were diagnosed within two weeks after the craniotomy. Postoperative administration of antibiotics reduced the incidence of PCII. Independent risk factors included clean-contaminated craniotomy, prolonged operation (> 7 h), external cerebrospinal fluid (CSF) drainage/monitoring device placement, and postoperative CSF leakage. Patients ≤ 45 years old were more susceptible to infection. Compared with supratentorial tumors, tumors located in the infratentorial or intraventricular regions were more vulnerable to PCII. Gram-positive bacteria were the most common causative pathogens isolated from the CSF samples, accounting for 82.0% of the PCII cases. Risk factors for PCII can be identified early in the perioperative period. These findings raise the possibility of improving the clinical outcomes of patients with brain tumors who undergo craniotomy.

Application of COMPONT Medical Adhesive Glue for Tension-Reduced Duraplasty in Decompressive Craniotomy

PubMed Central

Zhou, Yujia; Wang, Gesheng; Liu, Jialin; Du, Yong; Wang, Lei; Wang, Xiaoyong

2016-01-01

Background The aim of this study was to evaluate the application of medical adhesive glue for tension-reduced duraplasty in decompressive craniotomy. Material/Methods A total of 56 cases were enrolled for this study from Jan 2013 to May 2015. All patients underwent decompressive craniotomy and the dura was repaired in all of them with tension-reduced duraplasty using the COMPONT medical adhesive to glue artificial dura together. The postoperative complications and the healing of dura mater were observed and recorded. Results No wound infection, epidural or subdural hematoma, cerebrospinal fluid leakage, or other complications associated with the procedure occurred, and there were no allergic reactions to the COMPONT medical adhesive glue. The second-phase surgery of cranioplasty was performed at 3 to 6 months after the decompressive craniotomy in 32 out of the 56 cases. During the cranioplasty we observed no adherence of the artificial dura mater patch to the skin flap, no residual COMPONT glue, or hydropic or contracture change of tissue at the surgical sites. Additionally, no defect or weakening of the adherence between the artificial dura mater patch and the self dura matter occurred. Conclusions COMPONT medical adhesive glue is a safe and reliable tool for tension-reduced duraplasty in decompressive craniotomy. PMID:27752035

Intraoperative seizures during craniotomy under general anesthesia.

PubMed

Howe, John; Lu, Xiaoying; Thompson, Zoe; Peterson, Gordon W; Losey, Travis E

2016-05-01

An acute symptomatic seizure is a clinical seizure occurring at the time of or in close temporal association with a brain insult. We report an acute symptomatic seizure occurring during a surgical procedure in a patient who did not have a prior history of epilepsy and who did not have a lesion associated with an increased risk of epilepsy. To characterize the incidence and clinical features of intraoperative seizures during craniotomy under general anesthesia, we reviewed cases where continuous EEG was acquired during craniotomy. Records of 400 consecutive cases with propofol as general anesthesia during craniotomy were reviewed. Demographic data, indication for surgery, clinical history, history of prior seizures, duration of surgery and duration of burst suppression were recorded. Cases where seizures were observed were analyzed in detail. Two out of 400 patients experienced intraoperative seizures, including one patient who appeared to have an acute symptomatic seizure related to the surgical procedure itself and a second patient who experienced two seizures likely related to an underlying diagnosis of epilepsy. This is the first report of an acute symptomatic seizure secondary to a neurosurgical procedure. Overall, 0.5% of patients monitored experienced seizures, indicating that intraoperative seizures are rare, and EEG monitoring during craniotomies is of low yield in detecting seizures. Copyright © 2016. Published by Elsevier Ltd.

Feasibility of Piezoelectric Endoscopic Transsphenoidal Craniotomy: A Cadaveric Study

PubMed Central

Tomazic, Peter Valentin; Gellner, Verena; Koele, Wolfgang; Hammer, Georg Philipp; Braun, Eva Maria; Gerstenberger, Claus; Clarici, Georg; Holl, Etienne; Braun, Hannes; Stammberger, Heinz; Mokry, Michael

2014-01-01

Objective. Endoscopic transsphenoidal approach has become the gold standard for surgical treatment of treating pituitary adenomas or other lesions in that area. Opening of bony skull base has been performed with burrs, chisels, and hammers or standard instruments like punches and circular top knives. The creation of primary bone flaps—as in external craniotomies—is difficult.The piezoelectric osteotomes used in the present study allows creating a bone flap for endoscopic transnasal approaches in certain areas. The aim of this study was to prove the feasibility of piezoelectric endoscopic transnasal craniotomies. Study Design. Cadaveric study. Methods. On cadaveric specimens (N = 5), a piezoelectric system with specially designed hardware for endonasal application was applied and endoscopic transsphenoidal craniotomies at the sellar floor, tuberculum sellae, and planum sphenoidale were performed up to a size of 3–5 cm2. Results. Bone flaps could be created without fracturing with the piezoosteotome and could be reimplanted. Endoscopic handling was unproblematic and time required was not exceeding standard procedures. Conclusion. In a cadaveric model, the piezoelectric endoscopic transsphenoidal craniotomy (PETC) is technically feasible. This technique allows the surgeon to create a bone flap in endoscopic transnasal approaches similar to existing standard transcranial craniotomies. Future trials will focus on skull base reconstruction using this bone flap. PMID:24689037

Thermal Evolution of Diapirs with Complex Mantle Wedge Flow

NASA Astrophysics Data System (ADS)

Sylvia, R. T.; Kincaid, C.

2016-12-01

Subduction of oceanic lithosphere drives heat and mass exchange between Earth's interior and surface. One proposed transport mechanism for thermally and chemically distinct material through the wedge is the diapir model. The dominant driver of flow in the upper mantle is a mode of forced convection responding to motion of a tabular slab. A set of 4D laboratory experiments was conducted exploring the relationship between buoyancy flux and subduction parameters and subsequent effects on diapir transport. Variable subduction styles tested include downdip and rollback motion, slab gaps, slab steepening and backarc extension. The mantle is modeled using viscous glucose syrup with an Arrhenius type temperature dependent viscosity. Diapirs representing homogeneous mechanically mixed melange layer are introduced as buoyant fluid injected at multiple point sources situated along the surface of the sinking slab. Laboratory data is collected using high definition time-lapse photography and quantified using image velocimetry techniques. Here we present results from numerical simulation of the thermal evolution of spherical mantle wedge diapirs using 2D axisymmetric advection-diffusion model with internal diapir flow described by an analytic potential flow solution. A suite of wedge temperature profiles are used as thermal forcing on diapirs traversing the wedge along experimentally observed 4D ascent pathways. Scaling arguments suggest that for systems with Péclet number on the order of 15 advective heat transport is expected to dominate over diffusive heat transport, but the range of observed P-T-t paths and vigorous internal flow complicate this assumption. Interactions between modes of free (diapiric) and forced (wedge) convection lead to complex spatio-temporal variability in slab-to-arc connectivity patterns. Rollback induced toroidal flow, along trench changes in dip, convergence rate and backarc extension all produce a significant ( 500 km) trench-parallel transport component. Combined with diapir-diapir interactions these factors produce a spectrum of transit times and pathlengths, ranging from much shorter to much longer than those from simple 2D model estimates. Results highlight the broad range of expected internal temperature distributions derived from variable transit paths.

Current from a nano-gap hyperbolic diode using shape-factors: Theory

NASA Astrophysics Data System (ADS)

Jensen, Kevin L.; Shiffler, Donald A.; Peckerar, Martin; Harris, John R.; Petillo, John J.

2017-08-01

Quantum tunneling by field emission from nanoscale features or sharp field emission structures for which the anode-cathode gap is nanometers in scale ("nano diodes") experience strong deviations from the planar image charge lowered tunneling barrier used in the Murphy and Good formulation of the Fowler-Nordheim equation. These deviations alter the prediction of total current from a curved surface. Modifications to the emission barrier are modeled using a hyperbolic (prolate spheroidal) geometry to determine the trajectories along which the Gamow factor in a WKB-like treatment is undertaken; a quadratic equivalent potential is determined, and a method of shape factors is used to evaluate the corrected total current from a protrusion or wedge geometry.

Mini-Craniotomy Under Local Anesthesia for Chronic Subdural Hematoma: An Effective Choice for Elderly Patients and for Patients in a Resource-Strained Environment.

PubMed

Mahmood, Shaikh Danish; Waqas, Muhammad; Baig, Mirza Zain; Darbar, Aneela

2017-10-01

Mini-craniotomy for chronic subdural hematoma (CSDH) is associated with lower rates of recurrence. However, the procedure is performed mostly with the patient under general anesthesia (GA) and therefore frequently requires an intensive care unit (ICU) facility, especially in the elderly population. Because of the unavailability of ICU beds, and to avoid GA, we started to perform this procedure with the patient under local anesthesia (LA). This was a retrospective medical chart review conducted in the section of Neurosurgery at the Aga Khan Hospital in Karachi, Pakistan. The study duration was 1 year. We included patients aged 55 years or older undergoing surgery for CSDH. Clinical characteristics, hospital stay, and recurrence rates were compared between 2 groups, local versus general anesthesia. Thirty-five patients underwent mini-craniotomy for CSDH in the study period. Sixteen patients underwent mini-craniotomy under LA versus 19 patients for GA. Median age for the LA group was 67 years compared with 70 years in the GA group. Four patients from the LA group experienced postoperative complications versus 7 from the GA group. Only one patient in the LA group required an ICU bed in the postoperative period. There was no recurrence in LA group. The overall recurrence was 2.86%. Mini-craniotomy for CSDH under LA is an equally effective procedure compared with mini-craniotomy under GA. In addition, it minimizes the risks of GA in the elderly population and obviates the need of a postoperative ICU bed. It also reduces operative time and hospital stay as compared with GA. Copyright © 2017 Elsevier Inc. All rights reserved.

Outcome of elderly patients undergoing awake-craniotomy for tumor resection.

PubMed

Grossman, Rachel; Nossek, Erez; Sitt, Razi; Hayat, Daniel; Shahar, Tal; Barzilai, Ori; Gonen, Tal; Korn, Akiva; Sela, Gal; Ram, Zvi

2013-05-01

Awake-craniotomy allows maximal tumor resection, which has been associated with extended survival. The feasibility and safety of awake-craniotomy and the effect of extent of resection on survival in the elderly population has not been established. The aim of this study was to compare surgical outcome of elderly patients undergoing awake-craniotomy to that of younger patients. Outcomes of consecutive patients younger and older than 65 years who underwent awake-craniotomy at a single institution between 2003 and 2010 were retrospectively reviewed. The groups were compared for clinical variables and surgical outcome parameters, as well as overall survival. A total of 334 young (45.4 ± 13.2 years, mean ± SD) and 90 elderly (71.7 ± 5.1 years) patients were studied. Distribution of gender, mannitol treatment, hemodynamic stability, and extent of tumor resection were similar. Significantly more younger patients had a better preoperative Karnofsky Performance Scale score (>70) than elderly patients (P = 0.0012). Older patients harbored significantly more high-grade gliomas (HGG) and brain metastases, and fewer low-grade gliomas (P < 0.0001). No significantly higher rate of mortality, or complications were observed in the elderly group. Age was associated with increased length of stay (4.9 ± 6.3 vs. 6.6 ± 7.5 days, P = 0.01). Maximal extent of tumor resection in patients with HGG was associated with prolonged survival in the elderly patients. Awake-craniotomy is a well-tolerated and safe procedure, even in elderly patients. Gross total tumor resection in elderly patients with HGG was associated with prolonged survival. The data suggest that favorable prognostic factors for patients with malignant brain tumors are also valid in elderly patients.

Classifying multiple types of hand motions using electrocorticography during intraoperative awake craniotomy and seizure monitoring processes—case studies

PubMed Central

Xie, Tao; Zhang, Dingguo; Wu, Zehan; Chen, Liang; Zhu, Xiangyang

2015-01-01

In this work, some case studies were conducted to classify several kinds of hand motions from electrocorticography (ECoG) signals during intraoperative awake craniotomy & extraoperative seizure monitoring processes. Four subjects (P1, P2 with intractable epilepsy during seizure monitoring and P3, P4 with brain tumor during awake craniotomy) participated in the experiments. Subjects performed three types of hand motions (Grasp, Thumb-finger motion and Index-finger motion) contralateral to the motor cortex covered with ECoG electrodes. Two methods were used for signal processing. Method I: autoregressive (AR) model with burg method was applied to extract features, and additional waveform length (WL) feature has been considered, finally the linear discriminative analysis (LDA) was used as the classifier. Method II: stationary subspace analysis (SSA) was applied for data preprocessing, and the common spatial pattern (CSP) was used for feature extraction before LDA decoding process. Applying method I, the three-class accuracy of P1~P4 were 90.17, 96.00, 91.77, and 92.95% respectively. For method II, the three-class accuracy of P1~P4 were 72.00, 93.17, 95.22, and 90.36% respectively. This study verified the possibility of decoding multiple hand motion types during an awake craniotomy, which is the first step toward dexterous neuroprosthetic control during surgical implantation, in order to verify the optimal placement of electrodes. The accuracy during awake craniotomy was comparable to results during seizure monitoring. This study also indicated that ECoG was a promising approach for precise identification of eloquent cortex during awake craniotomy, and might form a promising BCI system that could benefit both patients and neurosurgeons. PMID:26483627

Pediatric awake craniotomy and intra-operative stimulation mapping.

PubMed

Balogun, James A; Khan, Osaama H; Taylor, Michael; Dirks, Peter; Der, Tara; Carter Snead Iii, O; Weiss, Shelly; Ochi, Ayako; Drake, James; Rutka, James T

2014-11-01

The indications for operating on lesions in or near areas of cortical eloquence balance the benefit of resection with the risk of permanent neurological deficit. In adults, awake craniotomy has become a versatile tool in tumor, epilepsy and functional neurosurgery, permitting intra-operative stimulation mapping particularly for language, sensory and motor cortical pathways. This allows for maximal tumor resection with considerable reduction in the risk of post-operative speech and motor deficits. We report our experience of awake craniotomy and cortical stimulation for epilepsy and supratentorial tumors located in and around eloquent areas in a pediatric population (n=10, five females). The presenting symptom was mainly seizures and all children had normal neurological examinations. Neuroimaging showed lesions in the left opercular (n=4) and precentral or peri-sylvian regions (n=6). Three right-sided and seven left-sided awake craniotomies were performed. Two patients had a history of prior craniotomy. All patients had intra-operative mapping for either speech or motor or both using cortical stimulation. The surgical goal for tumor patients was gross total resection, while for all epilepsy procedures, focal cortical resections were completed without any difficulty. None of the patients had permanent post-operative neurologic deficits. The patient with an epileptic focus over the speech area in the left frontal lobe had a mild word finding difficulty post-operatively but this improved progressively. Follow-up ranged from 6 to 27 months. Pediatric awake craniotomy with intra-operative mapping is a precise, safe and reliable method allowing for resection of lesions in eloquent areas. Further validations on larger number of patients will be needed to verify the utility of this technique in the pediatric population. Copyright © 2014 Elsevier Ltd. All rights reserved.

Supraorbital Versus Endoscopic Endonasal Approaches for Olfactory Groove Meningiomas: A Cost-Minimization Study.

PubMed

Gandhoke, Gurpreet S; Pease, Matthew; Smith, Kenneth J; Sekula, Raymond F

2017-09-01

To perform a cost-minimization study comparing the supraorbital and endoscopic endonasal (EEA) approach with or without craniotomy for the resection of olfactory groove meningiomas (OGMs). We built a decision tree using probabilities of gross total resection (GTR) and cerebrospinal fluid (CSF) leak rates with the supraorbital approach versus EEA with and without additional craniotomy. The cost (not charge or reimbursement) at each "stem" of this decision tree for both surgical options was obtained from our hospital's finance department. After a base case calculation, we applied plausible ranges to all parameters and carried out multiple 1-way sensitivity analyses. Probabilistic sensitivity analyses confirmed our results. The probabilities of GTR (0.8) and CSF leak (0.2) for the supraorbital craniotomy were obtained from our series of 5 patients who underwent a supraorbital approach for the resection of an OGM. The mean tumor volume was 54.6 cm 3 (range, 17-94.2 cm 3 ). Literature-reported rates of GTR (0.6) and CSF leak (0.3) with EEA were applied to our economic analysis. Supraorbital craniotomy was the preferred strategy, with an expected value of $29,423, compared with an EEA cost of $83,838. On multiple 1-way sensitivity analyses, supraorbital craniotomy remained the preferred strategy, with a minimum cost savings of $46,000 and a maximum savings of $64,000. Probabilistic sensitivity analysis found the lowest cost difference between the 2 surgical options to be $37,431. Compared with EEA, supraorbital craniotomy provides substantial cost savings in the treatment of OGMs. Given the potential differences in effectiveness between approaches, a cost-effectiveness analysis should be undertaken. Copyright © 2017 Elsevier Inc. All rights reserved.

[The treatment principles of frontal sinus tract after the frontal approach craniotomy].

PubMed

Yu, Huanxin; Li, Haiyan; Liu, Gang

2015-12-01

To investigate the causes, clinical manifestation and treatment principles of frontal sinus tract after the frontal approach craniotomy. The clinic data of 13 patients with frontal skin sinus tract after the frontal approach craniotomy were retrospectively analyzed. All of them were described in the clinical record to have undergone frontal sinus mucosa pushing down or shaving and bone wax filling in the frontal sinus during the surgery, of whom 3 cases had history of frontal abscess incision drainage. All patients were performed endoscopic frontal sinus surgery and forehead skin sinus tract excision and suture. All of the patients successfully recovered after one-stage operation, and the frontal skin sinus tract was healed. The frontal approach craniotomy with postoperative frontal sinus tract was related with the improper use of bone wax tamponade and sealing of frontal sinus. The treatment principles were to remove bone wax, remove inflammatory granulation tissue around the sinus tract, and to open frontal sinus and promote frontal sinus drainage.

Ethical challenges with awake craniotomy for tumor.

PubMed

Kirsch, Brandon; Bernstein, Mark

2012-01-01

Awake brain surgery is useful for the treatment of a number of conditions such as epilepsy and brain tumor, as well as in functional neurosurgery. Several studies have been published regarding clinical results and outcomes of patients who have undergone awake craniotomy but few have dealt with related ethical issues. The authors undertake to explore broadly the ethical issues surrounding awake brain surgery for tumor resection to encourage further consideration and discussion. Based on a review of the literature related to awake craniotomy and in part from the personal experience of the senior author, we conducted an assessment of the ethical issues associated with awake brain tumor surgery. The major ethical issues identified relate to: (1) lack of data; (2) utilization; (3) conflict of interest; (4) informed consent; (5) surgical innovation; and (6) surgical training. The authors respectfully suggest that the selection of patients for awake craniotomy needs to be monitored according to more consistent, objective standards in order to avoid conflicts of interest and potential harm to patients.

Anaesthetic management for awake craniotomy in brain glioma resection: initial experience in Military Hospital Mohamed V of Rabat.

PubMed

Meziane, Mohammed; Elkoundi, Abdelghafour; Ahtil, Redouane; Guazaz, Miloudi; Mustapha, Bensghir; Haimeur, Charki

2017-01-01

The awake brain surgery is an innovative approach in the treatment of tumors in the functional areas of the brain. There are various anesthetic techniques for awake craniotomy (AC), including asleep-awake-asleep technique, monitored anesthesia care, and the recent introduced awake-awake-awake method. We describe our first experience with anesthetic management for awake craniotomy, which was a combination of these techniques with scalp nerve block, and propofol/rémifentanil target controlled infusion. A 28-year-oldmale underwent an awake craniotomy for brain glioma resection. The scalp nerve block was performed and a low sedative state was maintained until removal of bone flap. During brain glioma resection, the patient awake state was maintained without any complications. Once, the tumorectomy was completed, the level of anesthesia was deepened and a laryngeal mask airway was inserted. A well psychological preparation, a reasonable choice of anesthetic techniques and agents, and continuous team communication were some of the key challenges for successful outcome in our patient.

[Difficult Ventilation Requiring Emergency Endotracheal Intubation during Awake Craniotomy Managed by Laryngeal Mask Airway].

PubMed

Matsuda, Asako; Mizota, Toshiyuki; Tanaka, Tomoharu; Segawa, Hajime; Fukuda, Kazuhiko

2016-04-01

We report a case of difficult ventilation requiring emergency endotracheal intubation during awake craniotomy managed by laryngeal mask airway (LMA). A 45-year-old woman was scheduled to receive awake craniotomy for brain tumor in the frontal lobe. After anesthetic induction, airway was secured using ProSeal LMA and patient was mechanically ventilated in pressure-control mode. Patient's head was fixed with head-pins at anteflex position, and the operation started. About one hour after the start of the operation, tidal volume suddenly decreased. We immediately started manual ventilation, but the airway resistance was extremely high and we could not adequately ventilate the patient. We administered muscle relaxant for suspected laryngospasm, but ventilatory status did not improve; so we decided to conduct emergency endotracheal intubation. We tried to intubate using Airwayscope or LMA-Fastrach, but they were not effective in our case. Finally trachea was intubated using transnasal fiberoptic bronchoscopy. We discuss airway management during awake craniotomy, focusing on emergency endotracheal intubation during surgery.

Use of Subdural Evacuating Port System Following Open Craniotomy with Excision of Native Dura and Membranes for Management of Chronic Subdural Hematoma

PubMed Central

Bach, Ashley; McDermott, Michael W.

2017-01-01

An 86-year-old woman was admitted to the intensive care unit with a chronic subdural hematoma (CSDH) and rapid onset of worsening neurological symptoms. She was taken to the operating room for a mini-craniotomy for evacuation of the CSDH including excision of the dura and CSDH membrane. Postoperatively, a subdural evacuation port system (SEPS) was integrated into the craniotomy site and left in place rather than a traditional subdural catheter drain to evacuate the subdural space postoperatively. The patient had a good recovery and improvement of symptoms after evacuation and remained clinically well after the SEPS was removed. We offer the technique of dura and CSDH membrane excision plus SEPS drain as an effective postoperative alternative to the standard craniotomy leaving the native dura intact with traditional subdural drain that overlies the cortical surface of the brain in treating patients with CSDH. PMID:28560123

Comparative analysis of monotherapy versus duotherapy antiseizure drug management for postoperative seizure control in patients undergoing an awake craniotomy.

PubMed

Eseonu, Chikezie I; Eguia, Francisco; Garcia, Oscar; Kaplan, Peter W; Quiñones-Hinojosa, Alfredo

2018-06-01

OBJECTIVE Postoperative seizures are a common complication in patients undergoing an awake craniotomy, given the cortical manipulation during tumor resection and the electrical cortical stimulation for brain mapping. However, little evidence exists about the efficacy of postoperative seizure prophylaxis. This study aims to determine the most appropriate antiseizure drug (ASD) management regimen following an awake craniotomy. METHODS The authors performed a retrospective analysis of data pertaining to patients who underwent an awake craniotomy for brain tumor from 2007 to 2015 performed by a single surgeon. Patients were divided into 2 groups, those who received a single ASD (the monotherapy group) and those who received 2 types of ASDs (the duotherapy group). Patient demographics, symptoms, tumor characteristics, hospitalization details, and seizure outcome were evaluated. Multivariable logistic regression was used to evaluate numerous clinical variables associated with postoperative seizures. RESULTS A total of 81 patients underwent an awake craniotomy for tumor resection of an eloquent brain lesion. Preoperative baseline characteristics were comparable between the 2 groups. The postoperative seizure rate was 21.7% in the monotherapy group and 5.7% in the duotherapy group (p = 0.044). Seizure outcome at 6 months' follow-up was assessed with the Engel classification scale. The duotherapy group had a significantly higher proportion of seizure-free (Engel Class I) patients than the monotherapy group (90% vs 60%, p = 0.027). The length of stay was similar, 4.02 days in the monotherapy group and 4.51 days in the duotherapy group (p = 0.193). The 90-day readmission rate was higher for the monotherapy group (26.1% vs 8.5% in the duotherapy group, p = 0.044). Multivariate logistic regression showed that preoperative seizure history was a significant predictor for postoperative seizures following an awake craniotomy (OR 2.08, 95% CI 0.56-0.90, p < 0.001). CONCLUSIONS Patients with a preoperative seizure history may be at a higher risk for postoperative seizures following an awake craniotomy and may benefit from better postoperative seizure control with postoperative ASD duotherapy.

A removable silicone elastomer seal reduces granulation tissue growth and maintains the sterility of recording chambers for primate neurophysiology

PubMed Central

Spitler, Kevin M.; Gothard, Katalin M.

2008-01-01

The maintenance of the sterility of craniotomies for serial acute neurophysiological recordings is exacting and time consuming yet is vital to the health of valuable experimental animals. We have developed a method to seal the craniotomy with surgical grade silicone elastomer (Silastic®) in a hermetically sealed chamber. Under these conditions the tissues in the craniotomy and the inside surface of the chamber remain unpopulated by bacteria. The silicone elastomer sealant retarded the growth of granulation tissue on the dura and reduced the procedures required to maintain ideal conditions for neurophysiological recordings. PMID:18241928

A multi-scale segmentation approach to filling gaps in Landsat ETM+ SLC-off images

USGS Publications Warehouse

Maxwell, S.K.; Schmidt, Gail L.; Storey, James C.

2007-01-01

On 31 May 2003, the Landsat Enhanced Thematic Plus (ETM+) Scan Line Corrector (SLC) failed, causing the scanning pattern to exhibit wedge-shaped scan-to-scan gaps. We developed a method that uses coincident spectral data to fill the image gaps. This method uses a multi-scale segment model, derived from a previous Landsat SLC-on image (image acquired prior to the SLC failure), to guide the spectral interpolation across the gaps in SLC-off images (images acquired after the SLC failure). This paper describes the process used to generate the segment model, provides details of the gap-fill algorithm used in deriving the segment-based gap-fill product, and presents the results of the gap-fill process applied to grassland, cropland, and forest landscapes. Our results indicate this product will be useful for a wide variety of applications, including regional-scale studies, general land cover mapping (e.g. forest, urban, and grass), crop-specific mapping and monitoring, and visual assessments. Applications that need to be cautious when using pixels in the gap areas include any applications that require per-pixel accuracy, such as urban characterization or impervious surface mapping, applications that use texture to characterize landscape features, and applications that require accurate measurements of small or narrow landscape features such as roads, farmsteads, and riparian areas.

Patients' perceptions of awake and outpatient craniotomy for brain tumor: a qualitative study.

PubMed

Khu, Kathleen Joy; Doglietto, Francesco; Radovanovic, Ivan; Taleb, Faisal; Mendelsohn, Daniel; Zadeh, Gelareh; Bernstein, Mark

2010-05-01

Routine and nonselective use of awake and outpatient craniotomy for supratentorial tumors has been shown to be safe and effective from a medical standpoint. In this study the authors aim was to explore patients' perceptions about awake and outpatient craniotomy. Qualitative research methodology was used. Two semistructured, open-ended interviews were conducted with 27 participants, who were ambulatory adult patients who underwent craniotomy for brain tumor excision between October 2008 and April 2009. The participants were each assigned to one of the following categories: 1) awake outpatient; 2) awake inpatient; 3) outpatient under general anesthesia; and 4) inpatient under general anesthesia. Interviews were audiotaped and transcribed, and the data were subjected to thematic analysis. The following 6 overarching themes emerged from the data: 1) patients had a positive experience with awake craniotomy; 2) patient satisfaction with outpatient surgery was high; 3) patients understood the rationale behind awake surgery; 4) patients were surprised that brain surgery can be done on an outpatient basis; 5) trust in one's surgeon was important; and 6) patients were more concerned about the disease than the procedure. The results reflected positively on the patients' awake and outpatient surgery experience, but there were some areas that require improvement, specifically perioperative pain control and postoperative care. These insights on patients' perspectives can lead to better delivery of care, and ultimately, improved health outcomes.

Evaluation of Language Function under Awake Craniotomy

PubMed Central

KANNO, Aya; MIKUNI, Nobuhiro

2015-01-01

Awake craniotomy is the only established way to assess patients’ language functions intraoperatively and to contribute to their preservation, if necessary. Recent guidelines have enabled the approach to be used widely, effectively, and safely. Non-invasive brain functional imaging techniques, including functional magnetic resonance imaging and diffusion tensor imaging, have been used preoperatively to identify brain functional regions corresponding to language, and their accuracy has increased year by year. In addition, the use of neuronavigation that incorporates this preoperative information has made it possible to identify the positional relationships between the lesion and functional regions involved in language, conduct functional brain mapping in the awake state with electrical stimulation, and intraoperatively assess nerve function in real time when resecting the lesion. This article outlines the history of awake craniotomy, the current state of pre- and intraoperative evaluation of language function, and the clinical usefulness of such functional evaluation. When evaluating patients’ language functions during awake craniotomy, given the various intraoperative stresses involved, it is necessary to carefully select the tasks to be undertaken, quickly perform all examinations, and promptly evaluate the results. As language functions involve both input and output, they are strongly affected by patients’ preoperative cognitive function, degree of intraoperative wakefulness and fatigue, the ability to produce verbal articulations and utterances, as well as perform synergic movement. Therefore, it is essential to appropriately assess the reproducibility of language function evaluation using awake craniotomy techniques. PMID:25925758

Impact of preoperative functional magnetic resonance imaging during awake craniotomy procedures for intraoperative guidance and complication avoidance.

PubMed

Trinh, Victoria T; Fahim, Daniel K; Maldaun, Marcos V C; Shah, Komal; McCutcheon, Ian E; Rao, Ganesh; Lang, Frederick; Weinberg, Jeffrey; Sawaya, Raymond; Suki, Dima; Prabhu, Sujit S

2014-01-01

We wanted to study the role of functional MRI (fMRI) in preventing neurological injury in awake craniotomy patients as this has not been previously studied. To examine the role of fMRI as an intraoperative adjunct during awake craniotomy procedures. Preoperative fMRI was carried out routinely in 214 patients undergoing awake craniotomy with direct cortical stimulation (DCS). In 40% of our cases (n = 85) fMRI was utilized for the intraoperative localization of the eloquent cortex. In the other 129 cases significant noise distortion, poor task performance and nonspecific BOLD activation precluded the surgeon from using the fMRI data. Compared with DCS, fMRI had a sensitivity and specificity, respectively, of 91 and 64% in Broca's area, 93 and 18% in Wernicke's area and 100 and 100% in motor areas. A new intraoperative neurological deficit during subcortical dissection was predictive of a worsened deficit following surgery (p < 0.001). The use of fMRI for intraoperative localization was, however, not significant in preventing worsened neurological deficits, both in the immediate postoperative period (p = 1.00) and at the 3-month follow-up (p = 0.42). The routine use of fMRI was not useful in identifying language sites as performed and, more importantly, practiced tasks failed to prevent neurological deficits following awake craniotomy procedures. © 2014 S. Karger AG, Basel.

A comparison study of immune-inflammatory response in electroacupuncture and transcutaneous electrical nerve stimulation for patients undergoing supratentorial craniotomy

PubMed Central

Li, Guoyan; Li, Shuqin; Sun, Lizhi; Lin, Fangcai; Wang, Baoguo

2015-01-01

Objective: The effect of transcutaneous electrical nerve stimulation (TENS) on immuno-inflammatory response was tested and the differences between electroacupuncture (EA) and TENS in immuno-inflammatory response in patients undergoing supratentorial craniotomy were explored. Methods: 51 patients received craniotomy were randomly divided into 3 groups: control (group C, n=18), EA (group A, n=19) and TENS (group T, n=14) groups. Blood samples were collected before anesthesia (T0) and 30 min (T1), 2 h (T2) and 4 h (T3) after induction of anesthesia to measure the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-8, IL-10, IgM, IgA and IgG. Results: No significant difference existed between group A and group T during craniotomy. IgM and IgA decreased significantly in group C compared with groups A and T at T2 and T3 time points. Compared with group C, there were significant differences in TNF-α, IgM and IgA levels at T0 in groups A and T; no significant difference was found in the levels of IgG, IL-10 and IL-8. Conclusion: EA and TENS could reduce immunosuppression in patients undergoing supratentorial craniotomy and it has significance in choice of treatment in immunosuppressive therapy. PMID:25785107

A comparison study of immune-inflammatory response in electroacupuncture and transcutaneous electrical nerve stimulation for patients undergoing supratentorial craniotomy

PubMed Central

Li, Guoyan; Li, Shuqin; Sun, Lizhi; Lin, Fangcai; Wang, Baoguo

2015-01-01

Objective: The effect of transcutaneous electrical nerve stimulation (TENS) on immuno-inflammatory response was tested and the differences between electroacupuncture (EA) and TENS in immuno-inflammatory response in patients undergoing supratentorial craniotomy were explored. Methods: 51 patients received craniotomy were divided randomly into 3 groups: control (group C, n=18), EA (group A, n=19) and TENS (group T, n=14) groups. Blood samples were collected before anesthesia (T0) and 30 min (T1), 2 h (T2) and 4 h (T3) after induction of anesthesia to measure the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-8, IL-10, IgM, IgA and IgG.. Results: No significant difference existed between groups A and group T during craniotomy. IgM and IgA decreased significantly in group C compared with groups A and T at T2 and T3 time points. Compared with group C, there were significant difference in TNF-α, IgM and IgA level at T0 in groups A and T; no significant difference was found in the levels of IgG, IL-10 and IL-8. Conclusion: EA and TENS could reduce immunosuppression in patients undergoing supratentorial craniotomy and it has significance in choice of treatment in immunosuppressive therapy. PMID:25932216

Evaluation of Language Function under Awake Craniotomy.

PubMed

Kanno, Aya; Mikuni, Nobuhiro

2015-01-01

Awake craniotomy is the only established way to assess patients' language functions intraoperatively and to contribute to their preservation, if necessary. Recent guidelines have enabled the approach to be used widely, effectively, and safely. Non-invasive brain functional imaging techniques, including functional magnetic resonance imaging and diffusion tensor imaging, have been used preoperatively to identify brain functional regions corresponding to language, and their accuracy has increased year by year. In addition, the use of neuronavigation that incorporates this preoperative information has made it possible to identify the positional relationships between the lesion and functional regions involved in language, conduct functional brain mapping in the awake state with electrical stimulation, and intraoperatively assess nerve function in real time when resecting the lesion. This article outlines the history of awake craniotomy, the current state of pre- and intraoperative evaluation of language function, and the clinical usefulness of such functional evaluation. When evaluating patients' language functions during awake craniotomy, given the various intraoperative stresses involved, it is necessary to carefully select the tasks to be undertaken, quickly perform all examinations, and promptly evaluate the results. As language functions involve both input and output, they are strongly affected by patients' preoperative cognitive function, degree of intraoperative wakefulness and fatigue, the ability to produce verbal articulations and utterances, as well as perform synergic movement. Therefore, it is essential to appropriately assess the reproducibility of language function evaluation using awake craniotomy techniques.

Comparison of the clinical efficacy of craniotomy and craniopuncture therapy for the early stage of moderate volume spontaneous intracerebral haemorrhage in basal ganglia: Using the CTA spot sign as an entry criterion.

PubMed

Ge, Chunyan; Zhao, Wangmiao; Guo, Hong; Sun, Zhaosheng; Zhang, Wanzeng; Li, Xiaowei; Yang, Xuehui; Zhang, Jinrong; Wang, Dongxin; Xiang, Yi; Mao, Jianhui; Zhang, Wenchao; Guo, Hao; Zhang, Yazhao; Chen, Jianchao

2018-06-01

Surgical treatment is widely used for haematoma removal in spontaneous intracerebral haemorrhage (ICH) patients, but there is controversy about the selection of surgical methods. The CT angiography (CTA) spot sign has been proven to be a promising factor predicting haematoma expansion and is recommended as an entry criterion for haemostatic therapy in patients with ICH. This trial was designed to evaluate the clinical efficacy of two surgical methods (haematoma removal by craniotomy and craniopuncture combined with urokinase infusion) for patients in the early stage (≤6h from symptom onset) of spontaneous ICH with a moderate haematoma volume (30 ml - 60 ml). From January 2012 to July 2017, 196 eligible patients treated in our institution were enrolled according to the inclusion criteria. The patients were divided into the CTA spot sign positive type and CTA spot sign negative type according to the presence or absence of the CTA spot sign. For each type, the patients were randomly assigned to two groups, i.e., the craniotomy group, in which patients underwent craniotomy with haematoma removal, and the craniopuncture group, in which patients underwent minimally invasive craniopuncture combined with urokinase infusion therapy. Neurological function was evaluated with the Scandinavian Stroke Scale (SSS) at day 14. The disability level and the activities of daily living were assessed using a modified Rankin Scale (mRS) and Barthel Index (BI) at day 90. Case fatalities were recorded at day 14 and 90. Complications were recorded during hospitalization. For the CTA spot sign positive type, the craniotomy group had a higher SSS than that in the craniopuncture group (P < 0.05) at day 14. The rebleeding rate was higher in the craniopuncture group than that in the craniotomy group (P < 0.05) during hospitalization. The craniotomy group had a lower mRS than that in the craniopuncture group (P < 0.01) and had a higher BI than that in the craniopuncture group (P < 0.05) at day 90. There was no statistically significant difference in the fatality rate between the two groups. For the CTA spot sign negative type, there were no significant differences in the SSS, mRS, BI, fatality rate and complication rate between the two groups. ICH can be divided into the CTA spot sign positive and negative type according to the presence or absence of the CTA spot sign. For the CTA spot sign positive type, patients can benefit from craniotomy with haematoma removal, which can reduce the postoperative rebleeding rate and improve the prognosis. For the CTA spot sign negative type, both craniotomy and craniopuncture are applicable. Considering simple procedure and minor surgical injury, craniopuncture can be a more reasonable choice. Copyright © 2018 Elsevier B.V. All rights reserved.

Three-dimensional Numerical Models of the Cocos-northern Nazca Slab Gap

NASA Astrophysics Data System (ADS)

Jadamec, M.; Fischer, K. M.

2012-12-01

In contrast to anisotropy beneath the middle of oceanic plates, seismic observations in subduction zones often indicate mantle flow patterns that are not easily explained by simple coupling of the subducting and overriding plates to the mantle. For example, in the Costa Rica-Nicaragua subduction zone local S shear wave splitting measurements combined with geochemical data indicate trench parallel flow in the mantle wedge with flow rates of 6.3-19 cm/yr, which is on order of or may be up to twice the subducting plate velocity. We construct geographically referenced high-resolution three-dimensional (3D) geodynamic models of the Cocos-northern Nazca subduction system to investigate what is driving the northwest directed, and apparently rapid, trench-parallel flow in the mantle wedge beneath Costa Rica-Nicaragua. We use the SlabGenerator code to construct a 3D plate configuration that is used as input to the community mantle convection code, CitcomCU. Models are run on over 400 CPUs on XSEDE, with a mesh resolution of up to 3 km at the plate boundary. Seismicity and seismic tomography delineate the shape and depth of the Cocos and northern Nazca slabs. The subducting plate thermal structure is based on a plate cooling model and ages from the seafloor age grid. Overriding plate thickness is constrained by the ages from the sea floor age grid where available and the depth to the lithosphere-asthenosphere boundary from the greatest negative gradient in absolute shear wave velocity. The geodynamic models test the relative controls of the change in the dip of the Cocos plate and the slab gap between the Cocos and northern Nazca plates in driving the mantle flow beneath Central America. The models also investigate the effect of a non-Newtonian rheology in dynamically generating a low viscosity mantle wedge and how this controls mantle flow rates. To what extent the Cocos-northern Nazca slab gap channelizes mantle flow between Central and South America has direct application to geochemical and geologic studies of the region. In addition, 3D geodynamic models of this kind can further test the hypothesis of rapid mantle flow in subduction zones as a global process and the non-Newtonian rheology as a mechanism for decoupling the mantle from lithospheric plate motion.

[Comparison of extent of postoperative hydrocephalus in patients between intervertional therapy with embolism and craniotomy occlusion in Hunt-Hess III-IV level aneurysm induced subarachnoid hemorrhage and their prognosis].

PubMed

Liu, Yang; Sun, Shengkai; Chen, Xuyi; Cheng, Shixiang; Qin, Zhizhen; Liu, Xiu; Chen, Xiaochu; Ning, Lili; Wang, Zhihong

2015-02-01

To analyze and compare the difference and prognosis between vascular embolization and craniotomy occlusion in patients suffering from aneurysmal subarachnoid hemorrhage (aSAH) with Hunt-Hess level III-IV, and acute postoperative hydrocephalus. A retrospective study was conducted on 767 patients who had undergone vascular embolization (vascular embolization group, n = 403) or craniotomy occlusion operation (craniotomy occlusion operation group, n = 364), and the patients with postoperative acute hydrocephalus were screened. The clinical data of patients of both groups was analyzed. By judging short-term prognosis in patients with hydrocephalus with Glasgow outcome scale (GOS) score estimated at discharge, the advantages and disadvantages of two surgical procedures were compared. The number of cases with postoperative hydrocephalus in vascular embolization group was 56 (13.90%), while that in craniotomy occlusion group was 33 (9.07%). The difference between the two groups of incidence of hydrocephalus was statistically significant (χ (2) = 4.350, P = 0.037). In 767 patients with aSAH, the incidence of hydrocephalus among the patients after the hematoma removal operation was significantly lower than that of patients without hematoma removal [3.07% (11/358) vs. 19.07% (78/409), χ (2) = 47.635, P = 0.000]. The incidence of hydrocephalus among the patients after ventricular drainage was significantly lower than that of patients without the drainage [2.77% (19/685) vs. 85.37% (70/82), χ (2) = 487.032, P = 0.000]. In 403 cases of vascular embolization group, the incidence of hydrocephalus in the patients after the hematoma removal operation was lower than that of patients without it [8.06% (5/62) vs. 14.96% (51/341), χ (2) = 2.082, P = 0.168]. The incidence of hydrocephalus in the patients after the ventricular drainage was lower than that of patients without drainage [2.59% (9/347) vs. 83.93% (47/56), χ (2) = 266.599, P = 0.000]. In 364 cases of craniotomy occlusion operation group, the incidence of hydrocephalus in the patients after hematoma removal operation was significantly lower than that of patients did not receive [2.03% (6/296) vs. 39.71% (27/68), χ (2) = 95.226, P = 0.000]. The incidence of hydrocephalus among the patients after the ventricular drainage was significantly lower than that of patients without drainage [2.96% (10/338) vs. 88.46% (23/26), χ (2) = 203.852, P = 0.000]. The difference in incidence of hydrocephalus between the patients who had hematoma removal surgery between vascular embolization group and craniotomy occlusion operation group was statistically significant [8.06% (5/62) vs. 2.03% (6/296), χ (2) = 4.411, P = 0.027], while no statistically difference was present in ventricular drainage patients [2.59% (9/347) vs. 2.96% (10/338), χ (2) = 0.085, P = 0.819]. There were 23 patients (41.07%) with good outcome (GOS score 4-5), while 33 (58.93%) with poor outcome (GOS score 1-3) in 56 patients undergone vascular embolization operation. Good result (GOS score 4-5) was shown in 21 (63.64%) and 12 (36.36%) with poor outcome (GOS score 1-3) among 33 patients with hydrocephalus after craniotomy occlusion operation, and the difference was statistically significant (χ (2) = 4.230, P = 0.039). Hematoma is one of the main factor contributing to the differences in the incidence of postoperative hydrocephalus of Hunt-Hess grade III-IV patients either receiving vascular embolization or craniotomy occlusion operation. Lateral ventricle drainage may not be the factor that contributes to the difference in incidence of hydrocephalus formation between the vascular embolization and craniotomy occlusion operation groups in Hunt-Hess level III-IV patients. The short term prognosis in the craniotomy occlusion operation group is superior to that of endovascular intervention embolization group.

Evaluation of a Fluorochlorozirconate Glass-Ceramic Storage Phosphor Plate for Gamma-Ray Computed Radiography

DOE PAGES

Leonard, Russell L.; Gray, Sharon K.; Alvarez, Carlos J.; ...

2015-05-21

In this paper, a fluorochlorozirconate (FCZ) glass-ceramic containing orthorhombic barium chloride crystals doped with divalent europium was evaluated for use as a storage phosphor in gamma-ray imaging. X-ray diffraction and phosphorimetry of the glass-ceramic sample showed the presence of a significant amount of orthorhombic barium chloride crystals in the glass matrix. Transmission electron microscopy and scanning electron microscopy were used to identify crystal size, structure, and morphology. The size of the orthorhombic barium chloride crystals in the FCZ glass matrix was very large, ~0.5–0.7 μm, which can limit image resolution. The FCZ glass-ceramic sample was exposed to 1 MeV gammamore » rays to determine its photostimulated emission characteristics at high energies, which were found to be suitable for imaging applications. Test images were made at 2 MeV energies using gap and step wedge phantoms. Gaps as small as 101.6 μm in a 440 stainless steel phantom were imaged using the sample imaging plate. Analysis of an image created using a depleted uranium step wedge phantom showed that emission is proportional to incident energy at the sample and the estimated absorbed dose. Finally, the results showed that the sample imaging plate has potential for gamma-ray-computed radiography and dosimetry applications.« less

Is a synthetic augmentation in medial open wedge high tibial osteotomies superior to no augmentation in terms of bone-healing?

PubMed

Ferner, Felix; Dickschas, Joerg; Ostertag, Helmut; Poske, Ulrich; Schwitulla, Judith; Harrer, Joerg; Strecker, Wolf

2016-01-01

Medial open-wedge high tibial osteotomy (MOWHTO) is an established method to treat unicompartimental osteoarthritis of the knee joint. However, augmentation of the created tibial gap after osteotomy is controversially discussed. We performed a prospective investigation of 49 consecutive cases of MOWHTO at our department. Patients were divided into two groups: group A consisted of 19 patients while group B consisted of 30 patients. In group A, the augmentation of the opening gap after osteotomy was filled with a synthetic bone graft, whereas group B received no augmentation. As an indicator for bone healing we investigated the non-union rate in our study population and compared the non-union-rate between the two groups. The non-union rate was 28% in group A (five of 19 patients had to undergo revision) which received synthetic augmentation, while it was 3.3% in group B (one of 30 patients had to undergo revision) which received no augmentation. The difference between the groups was statistically significant (p-value 0.027). With regard to bone healing after MOWHTO, synthetic augmentation was not superior to no augmentation in terms of non-union rates after surgery. In fact, we registered a significantly higher rate of non-union after augmentation with synthetic bone graft. III. Copyright © 2015 Elsevier B.V. All rights reserved.

Severe bradycardia and hypotension after connecting negative pressure to the subgaleal drain during craniotomy closure.

PubMed

Karamchandani, K; Chouhan, R S; Bithal, P K; Dash, H H

2006-05-01

Negative pressure drainage systems are often used after craniotomy for evacuation of potential bleeding. There are several reports of haemodynamic disturbances with epidural negative pressure drainage, but such reports are very few for subgaleal drains placed over the bone flap. We report a case in which a patient developed severe cardiovascular disturbances after the vacuum drainage was connected to a subgaleal drain after craniotomy for aneurysm clipping. The patient had no significant cardiac history, had an uneventful intra-operative course and yet developed bradycardia and hypotension, which were reproducible and severe enough to require atropine administration. Anaesthetists must be aware of these effects, so that they can anticipate and treat such complications.

High-Flow Nasal Oxygen in Patient With Obstructive Sleep Apnea Undergoing Awake Craniotomy: A Case Report.

PubMed

Wong, Jaclyn W M; Kong, Amy H S; Lam, Sau Yee; Woo, Peter Y M

2017-12-15

Patients with obstructive sleep apnea are frequently considered unsuitable candidates for awake craniotomy due to anticipated problems with oxygenation, ventilation, and a potentially difficult airway. At present, only a handful of such accounts exist in the literature. Our report describes the novel use of high-flow nasal oxygen therapy for a patient with moderate obstructive sleep apnea who underwent an awake craniotomy under deep sedation. The intraoperative application of high-flow nasal oxygen therapy achieved satisfactory oxygenation, maintained the partial carbon dioxide pressure within a reasonable range even during periods of deep sedation, permitted responsive patient monitoring during mapping, and provided excellent patient and surgeon satisfaction.

Material properties effects on the detonation spreading and propagation of diaminoazoxyfurazan (DAAF)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Francois, Elizabeth Green; Morris, John S; Novak, Alan M

2010-01-01

Recent dynamic testing of Diaminoazoxyfurazan (DAAF) has focused on understanding the material properties affecting the detonation propagation, spreading, behavior and symmetry. Small scale gap testing and wedge testing focus on the sensitivity to shock with the gap test including the effects of particle size and density. Floret testing investigates the detonation spreading as it is affected by particle size, density, and binder content. The polyrho testing illustrates the effects of density and binder content on the detonation velocity. Finally the detonation spreading effect can be most dramatically seen in the Mushroom and Onionskin tests where the variations due to densitymore » gradients, pressing methods and geometry can be seen on the wave breakout behavior.« less

Subdural Hematoma

DTIC Science & Technology

2006-07-01

characterization of more subtle associated CNS injuries. Treatment of nonacute subdural hematoma may involve craniotomy -guided hematoma evacuation...nature of this process. Note the ventricular shunt (arrow) in place for drainage of hydrocephalus, caused by significant mass effect on the...collections may require craniotomy . Because SDH may be under high intracranial pressure resultant from associated injuries, patients with the acute form

Burr-hole drainage for the treatment of acute epidural hematoma in coagulopathic patients: a report of eight cases.

PubMed

Habibi, Zohreh; Meybodi, Ali Tayebi; Haji Mirsadeghi, Seyed Mohammad; Miri, Seyed Mojtaba

2012-07-20

Craniotomy has been accepted as the treatment of choice for the management of acute epidural hematomas (AEDH). However, in practice, it seems possible to evacuate AEDH via a single burr hole instead of the traditional craniotomy in certain circumstances. Among 160 patients with AEDH meeting criteria for evacuation admitted to the emergency and accident division of our center between 2006 and 2009, we found 8 cases of hematoma appearing isodense to brain parenchyma on computed tomography (CT), who had concomitant coagulopathy. These patients were managed by burr-hole drainage for treatment of the liquefied AEDH. A closed drainage system was then kept in the epidural space for 3 days. In all 8 patients, AEDH was evacuated successfully via burr-hole placement over the site of hematoma. The level of consciousness and other symptoms improved within the first day, and no patient required an additional routine craniotomy. For patients with slowly-developing AEDH in the context of impaired coagulation, burr-hole evacuation and drainage might be a less invasive method of treatment compared to conventional craniotomy.

Intraoperative seizures and seizures outcome in patients underwent awake craniotomy.

PubMed

Yuan, Yang; Peizhi, Zhou; Xiang, Wang; Yanhui, Liu; Ruofei, Liang; Shu, Jiang; Qing, Mao

2016-11-25

Awake craniotomies (AC) could reduce neurological deficits compared with patients under general anesthesia, however, intraoperative seizure is a major reason causing awake surgery failure. The purpose of the study was to give a comprehensive overview the published articles focused on seizure incidence in awake craniotomy. Bibliographic searches of the EMBASE, MEDLINE,were performed to identify articles and conference abstracts that investigated the intraoperative seizure frequency of patients underwent AC. Twenty-five studies were included in this meta-analysis. Among the 25 included studies, one was randomized controlled trials and 5 of them were comparable studies. The pooled data suggested the general intraoperative seizure(IOS) rate for patients with AC was 8%(fixed effect model), sub-group analysis identified IOS rate for glioma patients was 8% and low grade patients was 10%. The pooled data showed early seizure rates of AC patients was 11% and late seizure rates was 35%. This systematic review and meta-analysis shows that awake craniotomy is a safe technique with relatively low intraoperative seizure occurrence. However, few RCTs were available, and the acquisition of further evidence through high-quality RCTs is highly recommended.

Awake craniotomy using electromagnetic navigation technology without rigid pin fixation.

PubMed

Morsy, Ahmed A; Ng, Wai Hoe

2015-11-01

We report our institutional experience using an electromagnetic navigation system, without rigid head fixation, for awake craniotomy patients. The StealthStation® S7 AxiEM™ navigation system (Medtronic, Inc.) was used for this technique. Detailed preoperative clinical and neuropsychological evaluations, patient education and contrast-enhanced MRI (thickness 1.5mm) were performed for each patient. The AxiEM Mobile Emitter was typically placed in a holder, which was mounted to the operating room table, and a non-invasive patient tracker was used as the patient reference device. A monitored conscious sedation technique was used in all awake craniotomy patients, and the AxiEM Navigation Pointer was used for navigation during the procedure. This offers the same accuracy as optical navigation, but without head pin fixation or interference with intraoperative neurophysiological techniques and surgical instruments. The application of the electromagnetic neuronavigation technology without rigid head fixation during an awake craniotomy is accurate, and offers superior patient comfort. It is recommended as an effective adjunctive technique for the conduct of awake surgery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Anaesthetic management for awake craniotomy in brain glioma resection: initial experience in Military Hospital Mohamed V of Rabat

PubMed Central

Meziane, Mohammed; Elkoundi, Abdelghafour; Ahtil, Redouane; Guazaz, Miloudi; Mustapha, Bensghir; Haimeur, Charki

2017-01-01

The awake brain surgery is an innovative approach in the treatment of tumors in the functional areas of the brain. There are various anesthetic techniques for awake craniotomy (AC), including asleep-awake-asleep technique, monitored anesthesia care, and the recent introduced awake-awake-awake method. We describe our first experience with anesthetic management for awake craniotomy, which was a combination of these techniques with scalp nerve block, and propofol/rémifentanil target controlled infusion. A 28-year-oldmale underwent an awake craniotomy for brain glioma resection. The scalp nerve block was performed and a low sedative state was maintained until removal of bone flap. During brain glioma resection, the patient awake state was maintained without any complications. Once, the tumorectomy was completed, the level of anesthesia was deepened and a laryngeal mask airway was inserted. A well psychological preparation, a reasonable choice of anesthetic techniques and agents, and continuous team communication were some of the key challenges for successful outcome in our patient. PMID:28904684

Wechsler Adult Intelligence Scale-Revised Block Design broken configuration errors in nonpenetrating traumatic brain injury.

PubMed

Wilde, M C; Boake, C; Sherer, M

2000-01-01

Final broken configuration errors on the Wechsler Adult Intelligence Scale-Revised (WAIS-R; Wechsler, 1981) Block Design subtest were examined in 50 moderate and severe nonpenetrating traumatically brain injured adults. Patients were divided into left (n = 15) and right hemisphere (n = 19) groups based on a history of unilateral craniotomy for treatment of an intracranial lesion and were compared to a group with diffuse or negative brain CT scan findings and no history of neurosurgery (n = 16). The percentage of final broken configuration errors was related to injury severity, Benton Visual Form Discrimination Test (VFD; Benton, Hamsher, Varney, & Spreen, 1983) total score and the number of VFD rotation and peripheral errors. The percentage of final broken configuration errors was higher in the patients with right craniotomies than in the left or no craniotomy groups, which did not differ. Broken configuration errors did not occur more frequently on designs without an embedded grid pattern. Right craniotomy patients did not show a greater percentage of broken configuration errors on nongrid designs as compared to grid designs.

MRimaging findings after ventricular puncture in patients with SAH.

PubMed

Tominaga, J; Shimoda, M; Oda, S; Kumasaka, A; Yamazaki, K; Tsugane, R

2001-11-01

Using magnetic resonance (MR) imaging, we studied brain injury from ventricular puncture performed during craniotomy in the acute stage of subarachnoid hemorrhage (SAH). 80 patients underwent craniotomy for aneurysm obliteration within 48 hr after SAH, ventricular puncture for drainage of cerebrospinal fluid (CSF) was performed to reduce intracranial pressure. MR imaging was performed within 3 days following surgery to measure the size of the lesion, and was repeated on postoperative days 14 and 30. Of the 80 patients with ventricular puncture preceding craniotomy, 65 (81%) showed MR evidence of brain injury from the puncture. Overall, 149 lesions were detected. According to coronal images, cortical injuries (54 cases), penetrating injury to tracts along the ventricular tube (55 cases), caudate injury (25 cases), and corpus callosum injury (15 cases). Brain injuries from ventricular puncture did not correlate significantly to patient outcome. While ventricular puncture and drainage of CSF can readily be performed to decrease brain volume at the time of craniotomy in acute-stage SAH, neurosurgeons should be aware of a surprisingly high incidence of brain injury complicating puncture.

Berengario's drill: origin and inspiration.

PubMed

Chorney, Michael A; Gandhi, Chirag D; Prestigiacomo, Charles J

2014-04-01

Craniotomies are among the oldest neurosurgical procedures, as evidenced by early human skulls discovered with holes in the calvaria. Though devices change, the principles to safely transgress the skull are identical. Modern neurosurgeons regularly use electric power drills in the operating theater; however, nonelectric trephining instruments remain trusted by professionals in certain emergent settings in the rare instance that an electric drill is unavailable. Until the late Middle Ages, innovation in craniotomy instrumentation remained stunted without much documented redesign. Jacopo Berengario da Carpi's (c. 1457-1530 CE) text Tractatus de Fractura Calvae sive Cranei depicts a drill previously unseen in a medical volume. Written in 1518 CE, the book was motivated by defeat over the course of Lorenzo II de'Medici's medical care. Berengario's interchangeable bit with a compound brace ("vertibulum"), known today as the Hudson brace, symbolizes a pivotal device in neurosurgery and medical tool design. This drill permitted surgeons to stock multiple bits, perform the craniotomy faster, and decrease equipment costs during a period of increased incidence of cranial fractures, and thus the need for craniotomies, which was attributable to the introduction of gunpowder. The inspiration stemmed from a school of thought growing within a population of physicians trained as mathematicians, engineers, and astrologers prior to entering the medical profession. Berengario may have been the first to record the use of such a unique drill, but whether he invented this instrument or merely adapted its use for the craniotomy remains clouded.

Which one is more effective for analgesia in infratentorial craniotomy? The scalp block or local anesthetic infiltration.

PubMed

Akcil, Eren Fatma; Dilmen, Ozlem Korkmaz; Vehid, Hayriye; Ibısoglu, Lutfiye Serap; Tunali, Yusuf

2017-03-01

The most painful stages of craniotomy are the placement of the pin head holder and the skin incision. The primary aim of the present study is to compare the effects of the scalp block and the local anesthetic infiltration with bupivacaine 0.5% on the hemodynamic response during the pin head holder application and the skin incision in infratentorial craniotomies. The secondary aims are the effects on pain scores and morphine consumption during the postoperative 24h. This prospective, randomized and placebo controlled study included forty seven patients (ASA I, II and III). The scalp block was performed in the Group S, the local anesthetic infiltration was performed in the Group I and the control group (Group C) only received remifentanil as an analgesic during the intraoperative period. The hemodynamic response to the pin head holder application and the skin incision, as well as postoperative pain intensity, cumulative morphine consumption and opioid related side effects were compared. The scalp block reduced the hemodynamic response to the pin head holder application and the skin incision in infratentorial craniotomies. The local anesthetic infiltration reduced the hemodynamic response to the skin incision. As well as both scalp block and local anesthetic infiltration reduced the cumulative morphine consumption in postoperative 24h. Moreover, the pain intensity was lower after scalp block in the early postoperative period. The scalp block may provide better analgesia in infratentorial craniotomies than local anesthetic infiltration. Copyright © 2017 Elsevier B.V. All rights reserved.

A randomised controlled trial of the effects of cryotherapy on pain, eyelid oedema and facial ecchymosis after craniotomy.

PubMed

Shin, Yong Soon; Lim, Nan Young; Yun, Sung-Cheol; Park, Kwang Ok

2009-11-01

To identify the effects of cryotherapy on patient discomfort following craniotomy. Following craniotomy, many patients suffer from unexpected discomfort, including pain, eyelid oedema and ecchymosis. Cryotherapy is regarded as a safe method for managing these postcraniotomy problems. Randomised controlled trial. A total of 97 Korean patients who underwent elective supratentorial craniotomy were randomly assigned to a cryotherapy or a control group. In the cryotherapy group, ice bags were applied to surgical wounds, and cold gel packs were applied to periorbital areas, for 20 minutes per hour, beginning three hours postoperatively and for three days thereafter. The level of patient pain was measured using the visual analogue scale while the eyelid oedema was measured using the Kara & Gokalan's scale. Ecchymosis was also classified according to its extent. The level of pain three hours after craniotomy was similar in the cryotherapy and control groups (57.9 vs. 58.7). Three days after surgery, pain had significantly decreased in the cryotherapy group (p = 0.021). After adjusting diagnosis by analysis of covariance (ANCOVA), pain score did not differ significantly between the two groups. The mean eyelid oedema scores were lower in the cryotherapy group than in the control group (0.59 vs. 2.29, p < 0.001), with ANCOVA showing that cryotherapy had a significant effect on eyelid oedema (p < 0.001). Pain (p = 0.047) and eyelid oedema (p < 0.001) in the cryotherapy group were significantly decreased over time. Ecchymosis were significantly less frequent in the cryotherapy (11/48, 22.9%) than in the control (26/49, 53.1%) group (p = 0.003). Logistic regression analysis showed that cryotherapy affected ecchymosis (p = 0.001). These results indicate that cryotherapy can control pain, eyelid oedema and facial ecchymosis after craniotomy. Cryotherapy, which is both convenient and cost-effective, can be used to prevent postoperative discomforts in a clinical setting.

Awake craniotomy for microsurgical obliteration of mycotic aneurysms: technical report of three cases.

PubMed

Lüders, Jürgen C; Steinmetz, Michael P; Mayberg, Marc R

2005-01-01

Infectious (mycotic) aneurysms that do not resolve with medical treatment require surgical obliteration, usually requiring sacrifice of the parent artery. In addition, patients with mycotic aneurysms frequently need subsequent cardiac valve repair, which often necessitates anticoagulation. Three cases of awake craniotomy for microsurgical clipping of mycotic aneurysms are presented. Awake minimally invasive craniotomy using frameless stereotactic guidance on the basis of computed tomographic angiography enables temporary occlusion of the parent artery with neurological assessment before obliteration of the aneurysm. A 56-year-old woman presented with progressively worsening mitral valve disease and a history of subacute bacterial endocarditis and subarachnoid hemorrhage 30 years previously. A cerebral angiogram revealed a 4-mm left middle cerebral artery (MCA) angular branch aneurysm, which required obliteration before mitral valve replacement. The second patient, a 64-year-old woman with a history of rheumatic fever, had an 8-mm right distal MCA aneurysm diagnosed in the setting of pulmonary abscess and worsening cardiac function as a result of mitral valve disease. The third patient, a 57-year-old man with a history of fevers, night sweats, and progressive mitral valve disease, had an enlarging left MCA angular branch aneurysm despite the administration of antibiotics. Because of their location on distal MCA branches, none of the aneurysms were amenable to preoperative test balloon occlusion. After undergoing stereotactic computed tomographic angiography with fiducial markers, the patients underwent a minimally invasive awake craniotomy with frameless stereotactic navigation. In all cases, the results of the neurological examination were unchanged during temporary parent artery occlusion and the aneurysms were successfully obliterated. Awake minimally invasive craniotomy for an infectious aneurysm located in eloquent brain enables awake testing before permanent clipping or vessel sacrifice. Combining frameless stereotactic navigation with computed tomographic angiography allowed us to perform the operation quickly through a small craniotomy with minimal exploration.

A compact LWIR hyperspectral system employing a microbolometer array and a variable gap Fabry-Perot interferometer employed as a Fourier transform spectrometer

NASA Astrophysics Data System (ADS)

Lucey, Paul G.; Hinrichs, John L.; Akagi, Jason

2012-06-01

A prototype long wave infrared Fourier transform spectral imaging system using a wedged Fabry-Perot interferometer and a microbolometer array was designed and built. The instrument can be used at both short (cm) and long standoff ranges (infinity focus). Signal to noise ratios are in the several hundred range for 30 C targets. The sensor is compact, fitting in a volume about 12 x12 x 4 inches.

Epidural abscess treated with a medial supraorbital craniotomy through an incision in the eyebrow. Case report.

PubMed

Rosen, David S; Shafizadeh, Stephen; Baroody, Fuad M; Yamini, Bakhtiar

2008-02-01

The authors describe a medial supraorbital craniotomy performed through a medial eyebrow skin incision to approach an epidural abscess located in the medial anterior fossa of the skull. An 8-year-old boy presented with fevers and facial swelling. Imaging demonstrated pansinusitis and an epidural fluid collection adjacent to the frontal sinus. A medial supraorbital craniotomy was performed to access and drain the epidural abscess. The supraorbital nerve laterally and the supratrochlear nerve medially were preserved by incising the frontalis muscle vertically, parallel to the course of the nerves, and dissecting the subperiosteal plane to mobilize the nerves. This approach may be a useful access corridor for other lesions located near the medial anterior fossa.

Conscious sedation for awake craniotomy in intraoperative magnetic resonance imaging operating theater

PubMed Central

Takrouri, Mohamad Said Maani; Shubbak, Firas A.; Al Hajjaj, Aisha; Maestro, Rolando F. Del; Soualmi, Lahbib; Alkhodair, Mashael H.; Alduraiby, Abrar M.; Ghanem, Najeeb

2010-01-01

This case report describes the first case in intraoperative magnetic resonance imaging operating theater (iMRI OT) (BrainSuite®) of awake craniotomy for frontal lobe glioma excision in a 24-year-old man undergoing eloquent cortex language mapping intraoperatively. As he was very motivated to take pictures of him while being operated upon, the authors adapted conscious sedation technique with variable depth according to Ramsey's scale, in order to revert to awake state to perform the intended neurosurgical procedure. The patient tolerated the situation satisfactorily and was cooperative till the finish, without any event. We elicit in this report the special environment of iMRI OT for lengthy operation in pinned fixed patient having craniotomy. PMID:25885085

The History of Awake Craniotomy in Hospital Universiti Sains Malaysia

PubMed Central

WAN HASSAN, Wan Mohd Nazaruddin

2013-01-01

Awake craniotomy is a brain surgery performed on awake patients and is indicated for certain intracranial pathologies. These include procedures that require an awake patient for electrocorticographic mapping or precise electrophysiological recordings, resection of lesions located close to or in the motor and speech of the brain, or minor intracranial procedures that aim to avoid general anaesthesia for faster recovery and earlier discharge. This type of brain surgery is quite new and has only recently begun to be performed in a few neurosurgical centres in Malaysia. The success of the surgery requires exceptional teamwork from the neurosurgeon, neuroanaesthesiologist, and neurologist. The aim of this article is to briefly describe the history of awake craniotomy procedures at our institution. PMID:24643321

Seismic evidence for widespread serpentinized forearc upper mantle along the Cascadia margin

USGS Publications Warehouse

Brocher, T.M.; Parsons, T.; Trehu, A.M.; Snelson, C.M.; Fisher, M.A.

2003-01-01

Petrologic models suggest that dehydration and metamorphism of subducting slabs release water that serpentinizes the overlying forearc mantle. To test these models, we use the results of controlled-source seismic surveys and earthquake tomography to map the upper mantle along the Cascadia margin forearc. We find anomalously low upper-mantle velocities and/or weak wide-angle reflections from the top of the upper mantle in a narrow region along the margin, compatible with recent teleseismic studies and indicative of a serpentinized upper mantle. The existence of a hydrated forearc upper-mantle wedge in Cascadia has important geological and geophysical implications. For example, shearing within the upper mantle, inferred from seismic reflectivity and consistent with its serpentinite rheology, may occur during aseismic slow slip events on the megathrust. In addition, progressive dehydration of the hydrated mantle wedge south of the Mendocino triple junction may enhance the effects of a slap gap during the evolution of the California margin.

Transonic flow past a wedge profile with detached bow wave

NASA Technical Reports Server (NTRS)

Vincenti, Walter G; Wagoner, Cleo B

1952-01-01

A theoretical study has been made of the aerodynamic characteristics at zero angle of attack of a thin, doubly symmetrical double-wedge profile in the range of supersonic flight speed in which the bow wave is detached. The analysis utilizes the equations of the transonic small-disturbance theory and involves no assumptions beyond those implicit in this theory. The mixed flow about the front half of the profile is calculated by relaxation solution of boundary conditions along the shock polar and sonic line. The purely subsonic flow about the rear of the profile is found by means of the method of characteristics specialized to the transonic small-disturbance theory. Complete calculations were made for four values of the transonic similarity parameter. These were found sufficient to bridge the gap between the previous results of Guderley and Yoshihara at a Mach number of 1 and the results which are readily obtained when the bow wave is attached and the flow is completely supersonic.

Pressure Distributions About Finite Wedges in Bounded and Unbounded Subsonic Streams

NASA Technical Reports Server (NTRS)

Donoughe, Patrick L; Prasse, Ernst I

1953-01-01

An analytical investigation of incompressible flow about wedges was made to determine effects of tunnel-wedge ratio and wedge angle on the wedge pressure distributions. The region of applicability of infinite wedge-type velocity distribution was examined for finite wedges. Theoretical and experimental pressure coefficients for various tunnel-wedge ratios, wedge angles, and subsonic Mach numbers were compared.

Neurologic Deterioration Due to Brain Sag After Bilateral Craniotomy for Subdural Hematoma Evacuation.

PubMed

Liu, James K C

2018-06-01

Intracranial hypotension from cerebrospinal fluid (CSF) hypovolemia resulting in cerebral herniation is a rare but known complication that can occur after neurosurgical procedures, usually encountered in correlation with perioperative placement of a lumbar subarachnoid drain. Decrease in CSF volume resulting in loss of buoyancy results in downward herniation of the brain without contributing mass effect, causing a phenomenon known as brain sag. Unreported previously is brain sag occurring without concomitant occult CSF leak or lumbar drainage. This case report describes a patient who underwent bilateral craniotomies for subacute on chronic subdural hematoma with successful decompression but experienced acute neurologic deterioration secondary to brain sag. Despite an initial improvement in neurologic function, he subsequently experienced progressive neurologic deterioration with evidence of cerebral herniation on neuroimaging, without evidence of continued mass effect on the brain parenchyma. After a diagnosis of brain sag was determined based on imaging criteria, the patient was placed in a flat position, which resulted in rapid improvement in his neurologic function without any further intervention. This case is unique in comparison with previous reports of intracranial hypotension after craniotomy in that the symptoms were completely reversed with positioning alone, without any evidence of active or occult CSF drainage. This report emphasizes that the diagnosis of brain sag should be taken into consideration when there is an unknown reason for neurologic decline after craniotomy, particularly bilateral craniotomies, if the imaging indicates herniation with imaging findings consistent with intracranial hypotension, without evidence of overlying mass effect. Copyright © 2018 Elsevier Inc. All rights reserved.

The effect of single low-dose dexamethasone on vomiting during awake craniotomy.

PubMed

Kamata, Kotoe; Morioka, Nobutada; Maruyama, Takashi; Komayama, Noriaki; Nitta, Masayuki; Muragaki, Yoshihiro; Kawamata, Takakazu; Ozaki, Makoto

2016-12-01

Intraoperative vomiting leads to serious respiratory complications that could influence the surgical decision-making process for awake craniotomy. However, the use of antiemetics is still limited in Japan. The aim of this study was to investigate the effect of prophylactically administered single low-dose dexamethasone on the incidence of vomiting during awake craniotomy. The frequency of hyperglycemia was also examined. We conducted a retrospective case review of awake craniotomy for glioma resection between 2012 and 2015. Of the 124 patients, 91 were included in the analysis. Dexamethasone was not used in 43 patients and the 48 remaining patients received an intravenous bolus of 4.95 mg dexamethasone at anesthetic induction. Because of stable operating conditions, no one required conscious sedation throughout functional mapping and tumor resection. Although dexamethasone pretreatment reduced the incidence of intraoperative vomiting (P = 0.027), the number of patients who complained of nausea was comparable (P = 0.969). No adverse events related to vomiting occurred intraoperatively. Baseline blood glucose concentration did not differ between each group (P = 0.143), but the samples withdrawn before emergence (P = 0.018), during the awake period (P < 0.0001) and at the end of surgery (P < 0.0001) showed significantly higher glucose levels in the dexamethasone group. Impaired wound healing was not observed in either group. A single low-dose of dexamethasone prevents intraoperative vomiting for awake craniotomy cases. However, as even a small dose of dexamethasone increases the risk for hyperglycemia, antiemetic prophylaxis with dexamethasone should be administered after careful consideration. Monitoring of perioperative blood glucose concentration is also necessary.

Prediction of in-depth gap heating ratios from wing glove model test data. [space shuttle orbiter

NASA Technical Reports Server (NTRS)

1977-01-01

In-depth gap heating ratios were predicted down RSI tile sidewalls based on temperature measurements obtained from the JSC arc-jet Wing Glove model tests in order to develop gap heating ratios which resulted in the best possible fit of test data and to produce a set of engineering verification heating ratios similar in shape to one another which could be used at various body points on the Orbiter during reentry. The Rockwell TPS Multidimensional heat conduction program was used to perform 3-D thermal analyses using a 3.0 in. thick section of a curved RSI tile with 283 nodal points. Correlation with test data shows that the predicted heating ratios were significantly higher down in the gap than the zero pressure values for T/C stacks 39 and 38 on the Wing Glove model. For stack 37 (in a low pressure region), the baseline heating ratio overpredicted the temperature data. This analysis, which showed that the heating ratios were a strong function of the product of pressure and pressure gradient, will be used to compare with recent Gap/Step and Ames Double Wedge test/analysis results in the effort to identify the Orbiter gap response to high delta P flight environment.

Conference Support - Surgery in Extreme Environments - Center for Surgical Innovation

DTIC Science & Technology

2007-01-01

flights. During this 16-day mission in April 1998, surgical procedures, including thoracotomies, laparotomies, craniotomies , laminectomies, and...fixation, craniotomy , laminectomy, and leg dissection. These experiments also permitted the evaluation of IV insertion using the autonomic protocol and...missions will be required to address: Repair of lacerations; wound cement, layered closure Incision and drainage of abscess Needle aspiration of

Awake craniotomy in a patient with ejection fraction of 10%: considerations of cerebrovascular and cardiovascular physiology.

PubMed

Meng, Lingzhong; Weston, Stephen D; Chang, Edward F; Gelb, Adrian W

2015-05-01

A 37-year-old man with nonischemic 4-chamber dilated cardiomyopathy and low-output cardiac failure (estimated ejection fraction of 10%) underwent awake craniotomy for a low-grade oligodendroglioma resection under monitored anesthesia care. The cerebrovascular and cardiovascular physiologic challenges and our management of this patient are discussed. Published by Elsevier Inc.

Delayed intracranial subdural empyema following burr hole drainage: Case series and literature review.

PubMed

Kim, You-Sub; Joo, Sung-Pil; Song, Dong-Jun; Kim, Sung-Hyun; Kim, Tae-Sun

2018-05-01

A subdural empyema (SDE) following burr hole drainage of a chronic subdural hematoma (CSDH) can be difficult to distinguish from a recurrence of the CSDH, especially when imaging data is limited to a computed tomography (CT) scan. All patients underwent burr hole drainage of the CSDH at first, and the appearance of the SDE occurred within one month. A contrast-enhanced magnetic resonance imaging (MRI) scan, with diffusion-weighted imaging (DWI), revealed both the SDE and diffuse meningitis in all patients. In Case 1, because the patient was very young, burr hole drainage of the SDE, rather than craniotomy, was performed. However, subsequent craniotomy was required due to recurrence of the SDE. In Cases 2 and 3, an initial craniotomy was performed without burr hole drainage. Symptoms improved for all patients, and each was discharged without any neurologic deficits or subsequent recurrence. Neurosurgeons should consider the possibility of infection if recurrence of CSDH occurs within 1 month following drainage of a subdural hematoma. A contrast-enhanced MRI with DWI should be performed to differentiate SDE from CSDH. In addition, surgical evacuation of the empyema via wide craniotomy is preferred to burr hole drainage.

Post-operative orofacial pain, temporomandibular dysfunction and trigeminal sensitivity after recent pterional craniotomy: preliminary study.

PubMed

Brazoloto, Thiago Medina; de Siqueira, Silvia Regina Dowgan Tesseroli; Rocha-Filho, Pedro Augusto Sampaio; Figueiredo, Eberval Gadelha; Teixeira, Manoel Jacobsen; de Siqueira, José Tadeu Tesseroli

2017-05-01

Surgical trauma at the temporalis muscle is a potential cause of post-craniotomy headache and temporomandibular disorders (TMD). The aim of this study was to evaluate the prevalence of pain, masticatory dysfunction and trigeminal somatosensory abnormalities in patients who acquired aneurysms following pterional craniotomy. Fifteen patients were evaluated before and after the surgical procedure by a trained dentist. The evaluation consisted of the (1) research diagnostic criteria for TMD, (2) a standardized orofacial pain questionnaire and (3) a systematic protocol for quantitative sensory testing (QST) for the trigeminal nerve. After pterional craniotomy, 80% of the subjects, 12 patients, developed orofacial pain triggered by mandibular function. The pain intensity was measured by using the visual analog scale (VAS), and the mean pain intensity was 3.7. The prevalence of masticatory dysfunction was 86.7%, and there was a significant reduction of the maximum mouth opening. The sensory evaluation showed tactile and thermal hypoesthesia in the area of pterional access in all patients. There was a high frequency of temporomandibular dysfunction, postoperative orofacial pain and trigeminal sensory abnormalities. These findings can help to understand several abnormalities that can contribute to postoperative headache or orofacial pain complaints after pterional surgeries.

[A Case of Psychogenic Tremor during Awake Craniotomy].

PubMed

Kujirai, Kazumasa; Kamata, Kotoe; Uno, Toshihiro; Hamada, Keiko; Ozaki, Makoto

2016-01-01

A 31-year-old woman with a left frontal and parietal brain tumor underwent awake craniotomy. Propofol/remifentanil general anesthesia was induced. Following craniotomy, anesthetic administrations ceased. The level of consciousness was sufficient and she was not agitated. However, the patient complained of nausea 70 minutes into the awake phase. Considering the adverse effects of antiemetics and the upcoming surgical strategy, we did not give any medications. Nausea disappeared spontaneously while the operation was suspended. When surgical intervention extended to the left caudate nucleus, involuntary movement, classified as a tremor, with 5-6 Hz frequency, abruptly occurred on her left forearm. The patient showed emotional distress. Tremor appeared on her right forearm and subsequently spread to her lower extremities. Intravenous midazolam and fentanyl could not reduce her psychological stress. Since the tremor disturbed microscopic observation, general anesthesia was induced. Consequently, the tremor disappeared and did not recur. Based on the anatomical ground and the medication status, her involuntary movement was diagnosed as psychogenic tremor. Various factors can induce involuntary movements. In fact, intraoperative management of nausea and vomiting takes priority during awake craniotomy, but we should be reminded that some antiemetics potentially induce involuntary movement that could be caused by surgery around basal ganglia.

Ammonia encephalopathy and awake craniotomy for brain language mapping: cause of failed awake craniotomy.

PubMed

Villalba Martínez, G; Fernández-Candil, J L; Vivanco-Hidalgo, R M; Pacreu Terradas, S; León Jorba, A; Arroyo Pérez, R

2015-05-01

We report the case of an aborted awake craniotomy for a left frontotemporoinsular glioma due to ammonia encephalopathy on a patient taking Levetiracetam, valproic acid and clobazam. This awake mapping surgery was scheduled as a second-stage procedure following partial resection eight days earlier under general anesthesia. We planned to perform the surgery with local anesthesia and sedation with remifentanil and propofol. After removal of the bone flap all sedation was stopped and we noticed slow mentation and excessive drowsiness prompting us to stop and control the airway and proceed with general anesthesia. There were no post-operative complications but the patient continued to exhibit bradypsychia and hand tremor. His ammonia level was found to be elevated and was treated with an infusion of l-carnitine after discontinuation of the valproic acid with vast improvement. Ammonia encephalopathy should be considered in patients treated with valproic acid and mental status changes who require an awake craniotomy with patient collaboration. Copyright © 2014 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Scalp marking for a craniotomy using a laser pointer during preoperative computed tomographic imaging: technical note.

PubMed

Kubo, S; Nakata, H; Sugauchi, Y; Yokota, N; Yoshimine, T

2000-05-01

The preoperative localization of superficial intracranial lesions is often necessary for accurate burr hole placement or craniotomy siting. It is not always easy, however, to localize the lesions over the scalp working only from computed tomographic images. We developed a simple method for such localization using a laser pointer during the preoperative computed tomographic examination. The angle of incidence, extending from a point on the scalp to the center of the computed tomographic image, is measured by the software included with the scanner. In the gantry, at the same angle as on the image, a laser is beamed from a handmade projector onto the patient's scalp toward the center of the gantry. The point illuminated on the patient's head corresponds to that on the image. The device and the method are described in detail herein. We applied this technique to mark the area for the craniotomy before surgery in five patients with superficial brain tumors. At the time of surgery, it was confirmed that the tumors were circumscribed precisely. The technique is easy to perform and useful in the preoperative planning for a craniotomy. In addition, the device is easily constructed and inexpensive.

Chronic subdural haematoma treated by craniotomy, durectomy, outer membranectomy and subgaleal suction drainage. Personal experience in 39 patients.

PubMed

Mohamed, E E H Hussein

2003-06-01

According to the CT and MRI appearances, 39 chronic subdural haematoma (CSDH) patients were suspected of having solid clots and/or a high likelihood of loculation. Craniotomy was planned from the start. Beside the better exposure, excision of the dura and outer membrane, assumed to be the source of haematoma fluid, this is an additional step to minimize the incidence of significant recollection. There were no additional operative or postoperative cranial and/or systemic complications when compared with other minor procedures. Two patients (5%) required once percutaneous tapping and aspiration. Accordingly, if a case is considered to be better managed with craniotomy, durectomy and outer membranectomy this is an easy and safe technique with minimal incidence of recollection, morbidity and mortality.

[Successful airway management using i-gel in 7 patients undergoing awake craniotomy].

PubMed

Matsunami, Katsuaki; Sanuki, Michiyoshi; Yasuuji, Masakazu; Nakanuno, Ryuichi; Kato, Takahiro; Kawamoto, Masashi

2014-07-01

In order to secure airway during awake craniotomy, we used i-gel to perform positive-pressure ventilation in 7 patients for their anesthetic management. During removal of a tumor around the motor speech center, anesthetic management including asleep-awake-asleep technique was applied for speech testing. The technique, insertion and re-insertion of i-gel, was needed and it was easy in all the patients. During positive-pressure ventilation, peak pressure, tidal volume both for inspiration and expiration, and endtidal-CO2 were not markedly altered. Leakage around i-gel, and its differences between inspiration and expiration were negligible, while the tidal volume was adequate. We conclude that i-gel is useful for anesthetic management for awake craniotomy procedure for both securing airway and ventilation.

Dynamic subcellular imaging of cancer cell mitosis in the brain of live mice.

PubMed

Momiyama, Masashi; Suetsugu, Atsushi; Kimura, Hiroaki; Chishima, Takashi; Bouvet, Michael; Endo, Itaru; Hoffman, Robert M

2013-04-01

The ability to visualize cancer cell mitosis and apoptosis in the brain in real time would be of great utility in testing novel therapies. In order to achieve this goal, the cancer cells were labeled with green fluorescent protein (GFP) in the nucleus and red fluorescent protein (RFP) in the cytoplasm, such that mitosis and apoptosis could be clearly imaged. A craniotomy open window was made in athymic nude mice for real-time fluorescence imaging of implanted cancer cells growing in the brain. The craniotomy window was reversibly closed with a skin flap. Mitosis of the individual cancer cells were imaged dynamically in real time through the craniotomy-open window. This model can be used to evaluate brain metastasis and brain cancer at the subcellular level.

Moral absolutism and abortion: Alan Donagan on the hysterectomy and craniotomy cases.

PubMed

Reynolds, Terrence

1985-07-01

Reynolds argues that the nonconsequentialist moral theory proposed by Alan Donagan in his book The Theory of Morality (University of Chicago Press; 1977) does not resolve the cases in which craniotomy or removal of a cancerous uterus appears necessary to save the life of a pregnant woman. Donagan's absolute prohibition against the murder of the innocent and his rejection of the principle of double effect have led him to view the fetus as a pursuer or assailant or to assert the theory of proleptic agreement--that in risk taking ventures the parties may agree that killing one person to save the lives of the others will be accepted. Reynolds holds these arguments to be inapplicable in therapeutic abortions involving craniotomy or hysterectomy and concludes that Donagan's absolutist theory must be reexamined.

[Scalp neuralgia and headache elicited by cranial superficial anatomical causes: supraorbital neuralgia, occipital neuralgia, and post-craniotomy headache].

PubMed

Shimizu, Satoru

2014-01-01

Most scalp neuralgias are supraorbital or occipital. Although they have been considered idiopathic, recent studies revealed that some were attributable to mechanical irritation with the peripheral nerve of the scalp by superficial anatomical cranial structures. Supraorbital neuralgia involves entrapment of the supraorbital nerve by the facial muscle, and occipital neuralgia involves entrapment of occipital nerves, mainly the greater occipital nerve, by the semispinalis capitis muscle. Contact between the occipital artery and the greater occipital nerve in the scalp may also be causative. Decompression surgery to address these neuralgias has been reported. As headache after craniotomy is the result of iatrogenic injury to the peripheral nerve of the scalp, post-craniotomy headache should be considered as a differential diagnosis.

Gaps, tears and seismic anisotropy around the subducting slabs of the Antilles

NASA Astrophysics Data System (ADS)

Schlaphorst, David; Kendall, J.-Michael; Baptie, Brian; Latchman, Joan L.; Tait, Steve

2017-02-01

Seismic anisotropy in and beneath the subducting slabs of the Antilles is investigated using observations of shear-wave splitting. We use a combination of teleseismic and local events recorded at three-component broadband seismic stations on every major island in the area to map anisotropy in the crust, the mantle wedge and the slab/sub-slab mantle. To date this is the most comprehensive study of anisotropy in this region, involving 52 stations from 8 seismic networks. Local event delay times (0.21 ± 0.12 s) do not increase with depth, indicating a crustal origin in anisotropy and an isotropic mantle wedge. Teleseismic delay times are much larger (1.34 ± 0.47 s), with fast shear-wave polarisations that are predominantly parallel to trend of the arc. These observations can be interpreted three ways: (1) the presence of pre-existing anisotropy in the subducting slab; (2) anisotropy due to sub-slab mantle flow around the eastern margin of the nearly stationary Caribbean plate; (3) some combination of both mechanisms. However, there are two notable variations in the trench-parallel pattern of anisotropy - trench-perpendicular alignment is observed in narrow regions east of Puerto Rico and south of Martinique. These observations support previously proposed ideas of eastward sublithospheric mantle flow through gaps in the slab. Furthermore, the pattern of anisotropy south of Martinique, near Saint Lucia is consistent with a previously proposed location for the boundary between the North and South American plates.

Nociceptive Neuropeptide Increases and Periorbital Allodynia in a Model of Traumatic Brain Injury

PubMed Central

Elliott, Melanie B.; Oshinsky, Michael L.; Amenta, Peter S.; Awe, Olatilewa O.; Jallo, Jack I.

2014-01-01

Objective This study tests the hypothesis that injury to the somatosensory cortex is associated with periorbital allodynia and increases in nociceptive neuropeptides in the brainstem in a mouse model of controlled cortical impact (CCI) injury. Methods Male C57BL/6 mice received either CCI or craniotomy-only followed by weekly periorbital von Frey (mechanical) sensory testing for up to 28 days post-injury. Mice receiving an incision only and naïve mice were included as control groups. Changes in calcitonin gene-related peptide (CGRP) and substance P (SP) within the brainstem were determined using enzyme-linked immunosorbent assay and immunohistochemistry, respectively. Activation of ionized calcium-binding adaptor molecule-1–labeled macrophages/microglia and glial fibrillary acidic protein (GFAP)-positive astrocytes were evaluated using immunohistochemistry because of their potential involvement in nociceptor sensitization. Results Incision-only control mice showed no changes from baseline periorbital von Frey mechanical thresholds. CCI significantly reduced mean periorbital von Frey thresholds (periorbital allodynia) compared with baseline and craniotomy-only at each endpoint, analysis of variance P < .0001. Craniotomy significantly reduced periorbital threshold at 14 days but not 7, 21, or 28 days compared with baseline threshold, P < .01. CCI significantly increased SP immunoreactivity in the brainstem at 7 and 14 days but not 28 days compared with craniotomy-only and controls, P < .001. CGRP levels in brainstem tissues were significantly increased in CCI groups compared with controls (incision-only and naïve mice) or craniotomy-only mice at each endpoint examined, P < .0001. There was a significant correlation between CGRP and periorbital allodynia (P < .0001, r = −0.65) but not for SP (r = 0.20). CCI significantly increased the number of macrophage/microglia in the injured cortex at each endpoint up to 28 days, although cell numbers declined over weeks post-injury, P < .001. GFAP+ immunoreactivity was significantly increased at 7 but not 14 or 28 days after CCI, P < .001. Craniotomy resulted in transient periorbital allodynia accompanied by transient increases in SP, CGRP, and GFAP immunoreactivity compared with control mice. There was no increase in the number of macrophage/microglia cells compared with controls after craniotomy. Conclusion Injury to the somatosensory cortex results in persistent periorbital allodynia and increases in brainstem nociceptive neuropeptides. Findings suggest that persistent allodynia and increased neuropeptides are maintained by mechanisms other than activation of macrophage/microglia or astrocyte in the injured somatosensory cortex. PMID:22568499

Modified irrigation hose placement in draping for craniotomy: provision of a free foot space for surgeons: technical note.

PubMed

Shimizu, S; Utsuki, S; Suzuki, S; Oka, H; Yamada, M; Fujii, K

2008-04-01

Sterility and utility are essential in surgical draping. For craniotomy, we modified the course of the irrigation hose to maintain a free foot space for the surgeon by connection with a suction bottle placed beside the patient's body through a slit made in the linen. This minor modification provides convenience to the surgeon during operations.

Potential for thermal damage to the blood–brain barrier during craniotomy: implications for intracortical recording microelectrodes

NASA Astrophysics Data System (ADS)

Shoffstall, Andrew J.; Paiz, Jen E.; Miller, David M.; Rial, Griffin M.; Willis, Mitchell T.; Menendez, Dhariyat M.; Hostler, Stephen R.; Capadona, Jeffrey R.

2018-06-01

Objective. Our objective was to determine how readily disruption of the blood–brain barrier (BBB) occurred as a result of bone drilling during a craniotomy to implant microelectrodes in rat cortex. While the phenomenon of heat production during bone drilling is well known, practices to evade damage to the underlying brain tissue are inconsistently practiced and reported in the literature. Approach. We conducted a review of the intracortical microelectrode literature to summarize typical approaches to mitigate drill heating during rodent craniotomies. Post mortem skull-surface and transient brain-surface temperatures were experimentally recorded using an infrared camera and thermocouple, respectively. A number of drilling conditions were tested, including varying drill speed and continuous versus intermittent contact. In vivo BBB permeability was assayed 1 h after the craniotomy procedure using Evans blue dye. Main results. Of the reviewed papers that mentioned methods to mitigate thermal damage during craniotomy, saline irrigation was the most frequently cited (in six of seven papers). In post mortem tissues, we observed increases in skull-surface temperature ranging from  +3 °C to  +21 °C, dependent on drill speed. In vivo, pulsed-drilling (2 s-on/2 s-off) and slow-drilling speeds (1000 r.p.m.) were the most effective methods we studied to mitigate heating effects from drilling, while inconclusive results were obtained with saline irrigation. Significance. Neuroinflammation, initiated by damage to the BBB and perpetuated by the foreign body response, is thought to play a key role in premature failure of intracortical recording microelectrodes. This study demonstrates the extreme sensitivity of the BBB to overheating caused by bone drilling. To avoid damage to the BBB, the authors recommend that craniotomies be drilled with slow speeds and/or with intermittent drilling with complete removal of the drill from the skull during ‘off’ periods. While saline alone was ineffective at preventing overheating, its use is still recommended to remove bone dust from the surgical site and to augment other cooling methods.

Organized Chronic Subdural Hematomas Treated by Large Craniotomy with Extended Membranectomy as the Initial Treatment

PubMed Central

Balevi, Mustafa

2017-01-01

Objective: The aim of this retrospective study is to evaluate the efficacy and incidence of complications of craniotomy and membranectomy in elderly patients for the treatment of organized chronic subdural hematoma (OCSH). Materials and Methods: We retrospectively reviewed a series of 28 consecutive patients suffering from OCSH, diagnosed by magnetic resonance imaging (MRI) or computer tomography (CT) to establish the degree of organization and determine the intrahematomal architecture including inner membrane ossification. The indication to perform a primary enlarged craniotomy as initial treatment for nonliquefied OCSH with multilayer loculations was based on the hematoma MRI appearance – mostly hyperintense in both T1- and T2-weighted images with a hypointense web- or net-like structure within the hematoma cavity or inner membrane calcification CT appearance - hyperdense. These cases have been treated by a large craniotomy with extended membranectomy as the initial treatment. However, the technique of a burr hole with closed system drainage for 24–72 h was chosen for cases of nonseptated and mostly liquefied Chronic Subdural Hematoma (CSDH). Results: Between 1998 and 2015, 148 consecutive patients were surgically treated for CSDH at our institution. Of these, 28 patients which have OSDH underwent a large craniotomy with extended membranectomy as the initial treatment. The average age of the patients was 69 (69.4 ± 12.1). Tension pneumocephalus (TP) has occurred in 22.8% of these patients (n = 28). Recurring subdural hemorrhage (RSH) in the operation area has occurred in 11.9% of these patients in the first 24 h. TP with RSH was seen in 4 of 8 TP patients (50%). Large epidural air was seen in one case. Postoperative seizures requiring medical therapy occurred in 25% of our patients. The average stay in the department of neurosurgery was 11 days, ranging from 7 to 28 days. Four patients died within 28 days after surgery; mortality rate was 14.28%. Conclusion: Large craniotomy and extended membrane excision for OSDH still carry a high rate of mortality and morbidity in elderly patients. TP, RSH, and postoperative seizures are frequently seen complications in elderly patients. PMID:29114271

Organized Chronic Subdural Hematomas Treated by Large Craniotomy with Extended Membranectomy as the Initial Treatment.

PubMed

Balevi, Mustafa

2017-01-01

The aim of this retrospective study is to evaluate the efficacy and incidence of complications of craniotomy and membranectomy in elderly patients for the treatment of organized chronic subdural hematoma (OCSH). We retrospectively reviewed a series of 28 consecutive patients suffering from OCSH, diagnosed by magnetic resonance imaging (MRI) or computer tomography (CT) to establish the degree of organization and determine the intrahematomal architecture including inner membrane ossification. The indication to perform a primary enlarged craniotomy as initial treatment for nonliquefied OCSH with multilayer loculations was based on the hematoma MRI appearance - mostly hyperintense in both T1- and T2-weighted images with a hypointense web- or net-like structure within the hematoma cavity or inner membrane calcification CT appearance - hyperdense. These cases have been treated by a large craniotomy with extended membranectomy as the initial treatment. However, the technique of a burr hole with closed system drainage for 24-72 h was chosen for cases of nonseptated and mostly liquefied Chronic Subdural Hematoma (CSDH). Between 1998 and 2015, 148 consecutive patients were surgically treated for CSDH at our institution. Of these, 28 patients which have OSDH underwent a large craniotomy with extended membranectomy as the initial treatment. The average age of the patients was 69 (69.4 ± 12.1). Tension pneumocephalus (TP) has occurred in 22.8% of these patients ( n = 28). Recurring subdural hemorrhage (RSH) in the operation area has occurred in 11.9% of these patients in the first 24 h. TP with RSH was seen in 4 of 8 TP patients (50%). Large epidural air was seen in one case. Postoperative seizures requiring medical therapy occurred in 25% of our patients. The average stay in the department of neurosurgery was 11 days, ranging from 7 to 28 days. Four patients died within 28 days after surgery; mortality rate was 14.28%. Large craniotomy and extended membrane excision for OSDH still carry a high rate of mortality and morbidity in elderly patients. TP, RSH, and postoperative seizures are frequently seen complications in elderly patients.

Mini-craniotomy as the primary surgical intervention for the treatment of chronic subdural hematoma--a retrospective analysis.

PubMed

Van Der Veken, Jorn; Duerinck, Johnny; Buyl, Ronald; Van Rompaey, Katrijn; Herregodts, Patrick; D'Haens, Jean

2014-05-01

The incidence of chronic subdural hematoma (CSDH) is increasing, but optimal treatment remains controversial. Recent meta-analyses suggest burr hole (BH) drainage is the best treatment because it provides optimal balance between recurrence and morbidity. Mini-craniotomy may offer supplementary technical advantages while maintaining equal or better outcomes. This study investigates the outcome of mini-craniotomy as the sole treatment in patients with CSDH. We analyzed all patients operated on for CSDH with mini-craniotomy in our neurosurgical center between 2005-2010. Baseline patient characteristics (age, sex, comorbidities, imaging characteristics, known risk factors for development of CSDH and neurological examination at presentation) and outcomes (mortality, complications, recurrence and neurological examination at discharge) were recorded. One hundred twenty-six adult patients were included, mean age was 73.9 (range 18 to 95) years old, and the sex ratio (M:F) was 2:1. Eighty-four percent of the patients showed clinical improvement at discharge, as shown by a decrease in the Markwalder score postoperatively (with 57 % Markwalder 0 and 23 % Markwalder 1). Recurrence rate was 8.7 %. Overall complication rate was 34.1 % (27.8 % medical complications and 6.3 % surgical complications). In-hospital mortality was 13.5 % (8.7 % due to pulmonary infections and 1.6 % to surgical complications). Preoperative Markwalder grade correlated significantly with complication rate, as did the presence of a neurodegenerative disease (p = 0.018). Factors significantly related to mortality in univariate analysis were arterial hypertension (p = 0.038), heart failure (p = 0.02), renal failure (p = 0.017), neurodegenerative disease (p = 0.001), cerebrovascular accident (p = 0.008) and coagulopathy (p = 0.019). Multivariate analysis was not able to confirm any significant relationship. This is the first published series of CSDH in which all consecutive patients were operated on by mini-craniotomy. The invasiveness and complication rate of mini-craniotomy are equal to those of burr hole treatment, but visualization is superior, resulting in lower recurrences. A randomized controlled trial is indicated to identify the best surgical strategy for the treatment of CSDH.

Awake craniotomy and electrophysiological mapping for eloquent area tumours.

PubMed

Chacko, Ari George; Thomas, Santhosh George; Babu, K Srinivasa; Daniel, Roy Thomas; Chacko, Geeta; Prabhu, Krishna; Cherian, Varghese; Korula, Grace

2013-03-01

An awake craniotomy facilitates radical excision of eloquent area gliomas and ensures neural integrity during the excision. The study describes our experience with 67 consecutive awake craniotomies for the excision of such tumours. Sixty-seven patients with gliomas in or adjacent to eloquent areas were included in this study. The patient was awake during the procedure and intraoperative cortical and white matter stimulation was performed to safely maximize the extent of surgical resection. Of the 883 patients who underwent craniotomies for supratentorial intraaxial tumours during the study period, 84 were chosen for an awake craniotomy. Sixty-seven with a histological diagnosis of glioma were included in this study. There were 55 men and 12 women with a median age of 34.6 years. Forty-two (62.6%) patients had positive localization on cortical stimulation. In 6 (8.9%) patients white matter stimulation was positive, five of whom had responses at the end of a radical excision. In 3 patients who developed a neurological deficit during tumour removal, white matter stimulation was negative and cessation of the surgery did not result in neurological improvement. Sixteen patients (24.6%) had intraoperative neurological deficits at the time of wound closure, 9 (13.4%) of whom had persistent mild neurological deficits at discharge, while the remaining 7 improved to normal. At a mean follow-up of 40.8 months, only 4 (5.9%) of these 9 patients had persistent neurological deficits. Awake craniotomy for excision of eloquent area gliomas enable accurate mapping of motor and language areas as well as continuous neurological monitoring during tumour removal. Furthermore, positive responses on white matter stimulation indicate close proximity of eloquent cortex and projection fibres. This should alert the surgeon to the possibility of postoperative deficits to change the surgical strategy. Thus the surgeon can resect tumour safely, with the knowledge that he has not damaged neurological function up to that point in time thus maximizing the tumour resection and minimizing neurological deficits. Copyright © 2012 Elsevier B.V. All rights reserved.

Coconut Model for Learning First Steps of Craniotomy Techniques and Cerebrospinal Fluid Leak Avoidance.

PubMed

Drummond-Braga, Bernardo; Peleja, Sebastião Berquó; Macedo, Guaracy; Drummond, Carlos Roberto S A; Costa, Pollyana H V; Garcia-Zapata, Marco T; Oliveira, Marcelo Magaldi

2016-12-01

Neurosurgery simulation has gained attention recently due to changes in the medical system. First-year neurosurgical residents in low-income countries usually perform their first craniotomy on a real subject. Development of high-fidelity, cheap, and largely available simulators is a challenge in residency training. An original model for the first steps of craniotomy with cerebrospinal fluid leak avoidance practice using a coconut is described. The coconut is a drupe from Cocos nucifera L. (coconut tree). The green coconut has 4 layers, and some similarity can be seen between these layers and the human skull. The materials used in the simulation are the same as those used in the operating room. The coconut is placed on the head holder support with the face up. The burr holes are made until endocarp is reached. The mesocarp is dissected, and the conductor is passed from one hole to the other with the Gigli saw. The hook handle for the wire saw is positioned, and the mesocarp and endocarp are cut. After sawing the 4 margins, mesocarp is detached from endocarp. Four burr holes are made from endocarp to endosperm. Careful dissection of the endosperm is done, avoiding liquid albumen leak. The Gigli saw is passed through the trephine holes. Hooks are placed, and the endocarp is cut. After cutting the 4 margins, it is dissected from the endosperm and removed. The main goal of the procedure is to remove the endocarp without fluid leakage. The coconut model for learning the first steps of craniotomy and cerebrospinal fluid leak avoidance has some limitations. It is more realistic while trying to remove the endocarp without damage to the endosperm. It is also cheap and can be widely used in low-income countries. However, the coconut does not have anatomic landmarks. The mesocarp makes the model less realistic because it has fibers that make the procedure more difficult and different from a real craniotomy. The model has a potential pedagogic neurosurgical application for freshman residents before they perform a real craniotomy for the first time. Further validity is necessary to confirm this hypothesis. Copyright © 2016 Elsevier Inc. All rights reserved.

Radial wedge flange clamp

DOEpatents

Smith, Karl H.

2002-01-01

A radial wedge flange clamp comprising a pair of flanges each comprising a plurality of peripheral flat wedge facets having flat wedge surfaces and opposed and mating flat surfaces attached to or otherwise engaged with two elements to be joined and including a series of generally U-shaped wedge clamps each having flat wedge interior surfaces and engaging one pair of said peripheral flat wedge facets. Each of said generally U-shaped wedge clamps has in its opposing extremities apertures for the tangential insertion of bolts to apply uniform radial force to said wedge clamps when assembled about said wedge segments.

Ultrasonic fluid densitometer having liquid/wedge and gas/wedge interfaces

DOEpatents

Greenwood, Margaret S.

2000-01-01

The present invention is an ultrasonic liquid densitometer that uses a material wedge having two sections, one with a liquid/wedge interface and another with a gas/wedge interface. It is preferred that the wedge have an acoustic impedance that is near the acoustic impedance of the liquid, specifically less than a factor of 11 greater than the acoustic impedance of the liquid. Ultrasonic signals are internally reflected within the material wedge. Density of a liquid is determined by immersing the wedge into the liquid and measuring reflections of ultrasound at the liquid/wedge interface and at the gas/wedge interface.

Endoscope-Assisted Keyhole Technique for Hypertensive Cerebral Hemorrhage in Elderly Patients: A Randomized Controlled Study in 184 Patients.

PubMed

Feng, Yi; He, Jianqing; Liu, Bin; Yang, Likun; Wang, Yuhai

2016-01-01

Hypertensive cerebral hemorrhage (HCH) is a potentially life-threatening cerebrovascular disease with high mortality. In case of a massive hematoma, surgical drainage is a crucial treatment. The aim of the present study was to assess the efficacy of the endoscope-assisted keyhole technique in elderly patients with intracerebral hematoma who needed a flap craniotomy as traditional treatment. One hundred-eighty-four elderly patients with HCH, who had craniotomy indications after conservative treatment for 6-24 hours after onset, were randomly divided into two groups. In the craniotomy group, traditional hematoma drainage was performed. In the keyhole group, an endoscope-assisted keyhole technique was used. Anesthesia time, blood loss, hematoma drainage rate, and complications were compared. The clinical primary outcome was the six-month efficacy rate (defined by the activities of daily living (ADL) score). Anesthesia time was longer in the craniotomy group (3.43 ± 0.65 vs. 1.53 ± 0.52 h, P < 0.01), and blood losses were more important (256 ± 129 vs. 96 ± 39 ml P < 0.01). There was no difference in hematoma drainage rate between the two groups (77.25 ± 13.44 vs. 83.52 ± 27.51% P > 0.05). Complications, including tracheotomy (P < 0.01), pulmonary infection (P < 0.01) and hypoproteinemia (P < 0.05) were more frequent in the craniotomy group. There was no difference in the occurrence of other complications, including revision surgery digestive tract ulcer and epilepsy. Proportion of patients with good prognosis (ADL I-III) was larger in the keyhole group (P < 0.05). In elderly HCH patients with an indication for hematoma drainage, better outcomes were achieved using an endoscope-assisted keyhole technique.

[Causes and management of frontal sinusitis after transfrontal craniotomy].

PubMed

Liu, T C; Yu, X F; Gu, Z W; Bai, W L; Wang, Z H; Cao, Z W

2018-02-01

Objective: The aim of this study is to investigate the causes and the strategy of frontal sinusitis after transfrontal craniotomy by endoscopic frontal sinus surgery and traditional surgery with facial incision. Method: A total of thirty-four patients with frontal sinusitis after transfrontal craniotomy were admitted, with the symptom of purulence stuff, headache and upper eyelid discharging. The onset time was 2.6 years on average. The frontal sinus CT and MRI images showed frontal sinusitis. Twenty-seven patients were treated with endoscopic frontal sinus surgery, and seven patient was treated with combined endoscopic and traditional frontal sinus surgery. In the revision surgery, the bone wax and inflammatory granulation tissue were cleaned out in both operational methods. The cure standard was that the postoperative frontal sinus inflammation disappeared and the drainage of the volume recess was unobstructed. Result: Thirty-four patients had a history of transfrontal craniotomy, and there was a record of bone wax packing in every operation. Among twenty-seven patients with endoscopic frontal sinus surgery, Twenty-five cases cured and two cases were operated twice. Seven patients were cured with combined endoscopic and traditional frontal sinus surgery. Conclusion: The frontal sinusitis after transfrontal craniotomy may be related to the inadequate sinus management, especially bone wax to be addressed to the frontal sinus ramming leading to frontal sinus mucosa secretion obstruction and poor drainage. Endoscopic frontal sinus surgery is a way of minimally invasive surgery. The satisfying curative effect can be obtained by endoscopic removal of bone wax, inflammatory granulation tissue, and the enlargement of frontal sinus aperture after exposure to the frontal sinus, and some cases was treated with both operation method.

The efficacy and safety of burr-hole craniotomy without continuous drainage for chronic subdural hematoma and subdural hygroma in children under 2 years of age.

PubMed

Matsuo, Kazuya; Akutsu, Nobuyuki; Otsuka, Kunitoshi; Yamamoto, Kazuki; Kawamura, Atsufumi; Nagashima, Tatsuya

2016-12-01

Various treatment modalities have been used in the management of chronic subdural hematoma and subdural hygroma (CSDH/SDHy) in children. However, few studies have examined burr-hole craniotomy without continuous drainage in such cases. Here, we retrospectively evaluated the efficacy and safety of burr-hole craniotomy without continuous drainage for CSDH/SDHy in children under 2 years old. We also aimed to determine the predictors of CSDH/SDHy recurrence. We conducted a retrospective chart review of 25 children under 2 years old who underwent burr-hole craniotomy without continuous drainage for CSDH/SDHy at a pediatric teaching hospital over a 10-year period. We analyzed the relationship between CSDH/SDHy recurrence and factors such as abusive head trauma, laterality of CSDH/SDHy, and subdural fluid collection type (hematoma or hygroma). CSDH/SDHy recurred in 5 of the 25 patients (20 %), requiring a second operation at an average of 0.92 ± 1.12 months after the initial procedure. The mean follow-up period was 25.1 ± 28.6 months. There were no complications related to either operation. None of the assessed factors were statistically associated with recurrence. Burr-hole craniotomy without continuous drainage for CSDH/SDHy appears safe in children aged under 2 years and results in a relatively low recurrence rate. No predictors of CSDH/SDHy recurrence were identified. Advantages of this method include avoiding external subdural drainage-related complications. However, burr-hole drainage may be more effective for CSDH, which our data suggests is more likely to recur than SDHy, providing the procedure is performed with specific efforts to reduce complications.

Assessment of molecular markers demonstrates concordance between samples acquired via stereotactic biopsy and open craniotomy in both anaplastic astrocytomas and glioblastomas.

PubMed

Gessler, Florian; Baumgarten, Peter; Bernstock, Joshua D; Harter, Patrick; Lescher, Stephanie; Senft, Christian; Seifert, Volker; Marquardt, Gerhard; Weise, Lutz

2017-06-01

The classification, treatment and prognosis of high-grade gliomas has been shown to correlate with the expression of molecular markers (e.g. MGMT promotor methylation and IDH1 mutations). Acquisition of tumor samples may be obtained via stereotactic biopsy or open craniotomy. Between the years 2009 and 2013, 22 patients initially diagnosed with HGGs via stereotactic biopsy, that ultimately underwent open craniotomy for resection of their tumor were prospectively included in an institutional glioma database. MGMT promotor analysis was performed using methylation-specific (MS)-PCR and IDH1R132H mutation analysis was performed using immunohistochemistry. Three patients (13.7%) exhibited IDH1R132H mutations in samples obtained via stereotactic biopsy. Tissue derived from stereotaxic biopsy was demonstrated to have MGMT promotor methylation in ten patients (45.5%), while a non-methylated MGMT promotor was demonstrated in ten patients (45.5%); inconclusive results were obtained for the remaining two patients (9%) within our cohort. The initial histologic grading, IDH1R132H mutation and MGMT promotor methylation results were confirmed using samples obtained during open craniotomy in all but one patient; here inconclusive MGMT promotor analysis was obtained in contrast to that which was obtained via stereotactic biopsy. Tumor samples acquired via stereotactic biopsy provide accurate information with regard to clinically relevant molecular markers that have been shown to impact patient care decisions. The profile of markers analyzed in our cohort was nearly concordant between those samples obtained via stereotactic biopsy or open craniotomy thereby suggesting that clinical decisions may be based on the molecular profile of the tumor samples obtained via stereotactic biopsy.

Surgery-Independent Language Function Decline in Patients Undergoing Awake Craniotomy.

PubMed

Gonen, Tal; Sela, Gal; Yanakee, Ranin; Ram, Zvi; Grossman, Rachel

2017-03-01

Despite selection process before awake-craniotomy, some patients experience an unexpected decline in language functions in the operating room (OR), compared with their baseline evaluation, which may impair their functional monitoring. To investigate this phenomenon we prospectively compared language function the day before surgery and on entrance to the OR. Data were collected prospectively from consecutive patients undergoing awake-craniotomy with intraoperative cortical mapping for resection of gliomas affecting language areas. Language functions of 79 patients were evaluated and compared 1-2 days before surgery and after entering the OR. Changes in functional linguistic performance were analyzed with respect to demographic, clinical, and pathologic characteristics. There was a significant decline in language function, beyond sedation effect, after entering the OR, (from median/interquartile range: 0.94/0.72-0.98 to median/interquartile range: 0.86/0.51-0.94; Z = -7.19, P < 0.001). Univariate analyses revealed that this decline was related to age, preoperative Karnofsky Performance Scale, tumor location, tumor pathology, and preexisting language deficits. Multivariate stepwise regression identified tumor pathology and the presence of preoperative language deficit as significant independent predictors for this functional decline. Patients undergoing awake-craniotomy may experience a substantial decline in language functioning after entering the OR. Tumor grade and the presence of preoperative language deficits were significant risk factors for this phenomenon, suggesting a possible relation between cognitive reserve, psychobehavioral coping abilities and histologic features of a tumor involving language areas. Capturing and identifying this unique population of patients who are prone to experience such language decline may improve our ability in the future to select patients eligible for awake-craniotomy. Copyright © 2016 Elsevier Inc. All rights reserved.

[Functional mapping using subdural electrodes combined with monitoring during awake craniotomy enabled preservation of function and extensive resection of a glioma adjacent to the parietal lobe language sites: a case report].

PubMed

Takebayashi, Kento; Saito, Taiichi; Nitta, Masayuki; Tamura, Manabu; Maruyama, Takashi; Muragaki, Yoshihiro; Okada, Yoshikazu

2015-01-01

Surgical resection of gliomas located in the dominant parietal lobe is difficult because this lesion is surrounded by multiple functional areas. Although functional mapping during awake craniotomy is very useful for resection of gliomas adjacent to eloquent areas, the limited time available makes it difficult to sufficiently evaluate multiple functions, such as language, calculative ability, distinction of right and left sides, and finger recognition. Here, we report a case of anaplastic oligodendroglioma, which was successfully treated with a combination of functional mapping using subdural electrodes and monitoring under awake craniotomy for glioma. A 32-year-old man presented with generalized seizure. Magnetic resonance imaging revealed a non-enhanced tumor in the left angular and supramarginal gyri. In addition, the tumor showed high accumulation on 11C-methionine positron emission tomography(PET)(tumor/normal brain tissue ratio=3.20). Preparatory mapping using subdural electrodes showed absence of brain function on the tumor lesion. Surgical removal was performed using cortical mapping during awake craniotomy with an updated navigation system using intraoperative magnetic resonance imaging(MRI). The tumor was resected until aphasia was detected by functional monitoring, and the extent of tumor resection was 93%. The patient showed transient transcortical aphasia and Gerstmann's syndrome after surgery but eventually recovered. The pathological diagnosis was anaplastic oligodendroglioma, and the patient was administered chemo-radiotherapy. The patient has been progression free for more than 2 years. The combination of subdural electrode mapping and monitoring during awake craniotomy is useful in order to achieve preservation of function and extensive resection for gliomas in the dominant parietal lobe.

Effect of intravenous parecoxib on post-craniotomy pain.

PubMed

Williams, D L; Pemberton, E; Leslie, K

2011-09-01

Pain management in craniotomy patients is challenging, with mild-to-moderate pain intensity, moderate-to-high risk of postoperative nausea and vomiting (PONV), and potentially catastrophic consequences of analgesic-related side-effects. The aim of this study was to determine whether i.v. parecoxib administered at dural closure during craniotomy decreased total morphine consumption and morphine-related side-effects compared with placebo. One hundred adult patients presenting for supratentorial craniotomy under propofol/remifentanil anaesthesia were randomized to receive parecoxib, 40 mg i.v., or placebo in a double-blind manner. All patients received local anaesthetic scalp infiltration, regular i.v. paracetamol, nurse-administered morphine in the post-anaesthesia care unit (PACU) until verbal analogue pain scores were ≤4/10 and patient-controlled morphine thereafter. Morphine consumption, pain intensity, and analgesia-related side-effects were recorded during the first 24 h after operation. Ninety-six patients (49 control and 47 parecoxib) were included in the analyses. Fifty-nine (61%) patients received morphine in the PACU and only one patient (control) did not receive any morphine in the postoperative period. There were no significant differences between the two groups in morphine consumption [20 (range: 0-102) vs 16 (range: 1-92) mg; P=0.38], pain intensity [excellent/very good pain relief in 78% of parecoxib patients; 74% of control patients (P=0.72)] or analgesia-related side-effects (PONV in 51% of parecoxib patients; 56% of control patients; P=0.55) in the first 24 h after operation. No major morbidity was recorded. Our study demonstrated no clinical benefit to adding i.v. parecoxib to local anaesthetic scalp infiltration, i.v. paracetamol, and patient-controlled i.v. morphine after supratentorial craniotomy.

Out-of-Body Experience During Awake Craniotomy.

PubMed

Bos, Eelke M; Spoor, Jochem K H; Smits, Marion; Schouten, Joost W; Vincent, Arnaud J P E

2016-08-01

The out-of-body experience (OBE), during which a person feels as if he or she is spatially removed from the physical body, is a mystical phenomenon because of its association with near-death experiences. Literature implicates the cortex at the temporoparietal junction (TPJ) as the possible anatomic substrate for OBE. We present a patient who had an out-of-body experience during an awake craniotomy for resection of low-grade glioma. During surgery, stimulation of subcortical white matter in the left TPJ repetitively induced OBEs, in which the patient felt as if she was floating above the operating table looking down on herself. We repetitively induced OBE by subcortical stimulation near the left TPJ during awake craniotomy. Diffusion tensor imaging tractography implicated the posterior thalamic radiation as a possible substrate for autoscopic phenomena. Copyright © 2016 Elsevier Inc. All rights reserved.

System design of a hand-held mobile robot for craniotomy.

PubMed

Kane, Gavin; Eggers, Georg; Boesecke, Robert; Raczkowsky, Jörg; Wörn, Heinz; Marmulla, Rüdiger; Mühling, Joachim

2009-01-01

This contribution reports the development and initial testing of a Mobile Robot System for Surgical Craniotomy, the Craniostar. A kinematic system based on a unicycle robot is analysed to provide local positioning through two spiked wheels gripping directly onto a patients skull. A control system based on a shared control system between both the Surgeon and Robot is employed in a hand-held design that is tested initially on plastic phantom and swine skulls. Results indicate that the system has substantially lower risk than present robotically assisted craniotomies, and despite being a hand-held mobile robot, the Craniostar is still capable of sub-millimetre accuracy in tracking along a trajectory and thus achieving an accurate transfer of pre-surgical plan to the operating room procedure, without the large impact of current medical robots based on modified industrial robots.

Effect of Head Insulation on the Total Time Required to Rewarm Postoperative Cardiac Surgery Patients.

DTIC Science & Technology

1992-05-01

two-hour period in the recovery room. Individuals were excluded from the study if they had cardiac surgery, craniotomies , surgeries precluding the use...years). Patients were excluded if they had: craniotomies , cardiac surgery, coagulation defects, 34 preoperative hyperthermia, or previous tympanoplasty...intraoperatively. 3. Postoperative mediastinal/chest tube drainage > 100 ml/hour for four hours. 4. Postoperative cardiac arrest during data collection period

Bioacoustic Signal Classification in Cat Auditory Cortex

DTIC Science & Technology

1991-06-14

Studies Preparations for the setup to record from awake animals in a behavioral setting were initiated with the help of Dr. William Jenkins, our...temporal muscle over the right hemisphere was then retracted and the lateral cortex exposed by a craniotomy . The dura overlaying the middle ectosylvian...sites. For recording topographically identified single neurons, a wire mesh was placed over the craniotomy and the space between the grid and cortex was

Spontaneous spinal cerebrospinal fluid leak as a cause of coma after craniotomy for clipping of an unruptured intracranial aneurysm.

PubMed

Schievink, Wouter I; Palestrant, David; Maya, M Marcel; Rappard, George

2009-03-01

Spontaneous spinal CSF leaks are best known as a cause of orthostatic headache, but may also be the cause of coma. The authors encountered a unique case of a spontaneous spinal CSF leak causing coma 2 days after craniotomy for clipping of an unruptured aneurysm. This 44-year-old woman with autosomal dominant polycystic kidney disease underwent an uneventful craniotomy for an incidental anterior choroidal artery aneurysm. No intraoperative spinal CSF drainage was used. Two days after surgery the patient became comatose with a left oculomotor nerve palsy. Computed tomography scanning revealed a right extraceberal hematoma and loss of gray-white matter differentiation. The hematoma was evacuated and a diagnosis of hemodialysis disequilibrium syndrome was made. Continuous hemodialysis and hyperosmolar therapy were instituted without any improvement. The CT scans were then reinterpreted as showing sagging of the brain, and the patient was placed in the Trendelenburg position which resulted in prompt improvement in her level of consciousness. A CT myelogram demonstrated an upper thoracic CSF leak that eventually required surgical correction. The patient made a complete neurological recovery. Neurological deterioration after craniotomy may be caused by brain sagging caused by a spontaneous spinal CSF leak, similar to intracranial hypotension due to intraoperative lumbar CSF drainage.

Awake craniotomy in a developmentally delayed blind man with cognitive deficits.

PubMed

Burbridge, Mark; Raazi, Mateen

2013-04-01

To describe the complex perioperative considerations and anesthetic management of a cognitively delayed blind adult male who underwent awake craniotomy to remove a left anterior temporal lobe epileptic focus. A 28-yr-old left-handed blind cognitively delayed man was scheduled for awake craniotomy to resect a left anterior temporal lobe epileptic focus due to intractable epilepsy despite multiple medications. His medical history was also significant for retinopathy of prematurity that rendered him legally blind in both eyes and an intracerebral hemorrhage shortly after birth that resulted in a chronic brain injury and developmental delay. His cognitive capacity was comparable with that of an eight year old. Since patient cooperation was the primary concern during the awake electrocorticography phase of surgery, careful assessment of the patient's ability to tolerate the procedure was undertaken. There was extensive planning between surgeons and anesthesiologists, and a patient-specific pharmacological strategy was devised to facilitate surgery. The operation proceeded without complication, the patient has remained seizure-free since the procedure, and his quality of life has improved dramatically. This case shows that careful patient assessment, effective interdisciplinary communication, and a carefully tailored anesthetic strategy can facilitate an awake craniotomy in a potentially uncooperative adult patient with diminished mental capacity and sensory deficits.

Factors affecting profitability for craniotomy.

PubMed

Popp, A John; Scrime, Todd; Cohen, Benjamin R; Feustel, Paul J; Petronis, Karen; Habiniak, Sharon; Waldman, John B; Vosburgh, Margaret M

2002-04-15

The authors studied factors influencing hospital profitability after craniotomy in patients who underwent craniotomy coded as diagnosis-related group (DRG) 1 (17 years of age with nontraumatic disease without complication) and who met their hospital's craniotomy pathway criteria and had a hospital length of stay 4 days or less during a 20-month period. Data in all patients meeting these criteria (76 cases) were collected and collated from various hospital databases. Twenty-one cases were profitable and 55 were not. Variables traditionally influencing cost of care, such as surgeon, procedure, length of operation, and pharmacy use had no significant effect on whether a patient was profitable. The most important influence on profitability was the individual payor. Cases in which care was reimbursed under the prospective payment system based on DRGs were nearly always profitable whereas those covered by per diem plans were nearly always nonprofitable. 1) Hospital information systems should be customized to deliver consolidated data for timely analysis of cost of care for individual patients. This information may be useful in negotiating profitable contracts. 2) A clinical pathway was successful in reducing the difference in cost of care between profitable and nonprofitable postcraniotomy cases. 3) In today's health care environment both cost containment and revenue assume importance in determining profitability.

Shampoo after craniotomy: a pilot study.

PubMed

Ireland, Sandra; Carlino, Karen; Gould, Linda; Frazier, Fran; Haycock, Patricia; Ilton, Suzin; Deptuck, Rachel; Bousfield, Brenda; Verge, Donna; Antoni, Karen; MacRae, Louise; Renshaw, Heather; Bialachowski, Ann; Chagnon, Carol; Reddy, Kesava

2007-01-01

The primary goal of this study was to assess the effect of postoperative hair-washing on incision infection and health-related quality of life (HRQOL) in craniotomy patients. The objectives of this study were to 1) determine the effect of postoperative hair-washing on incision infection and HRQOL, 2) provide evidence to support postoperative patient hygienic care, and 3) develop neurosurgical nursing research capacity Does hair-washing 72 hours after craniotomy and before suture or clip removal influence postoperative incision infection and postoperative HRQOL? A prospective cohort of 100 adult patients was randomized to hair-washing 72-hours postoperatively (n = 48), or no hair washing until suture or clip removal (n = 52). At five to -10 days postoperatively, sutures or clips were removed, incisions were assessed using the ASEPSIS Scale (n = 85) and participants were administered the SF-12 Health Survey (n = 71). At 30 days postoperatively, incisions (n = 70) were reassessed. No differences were found between hair-washing and no hair-washing groups for ASEPSIS scores at five to 10 days and 30 days, and total SF-12 scores at five to 10 days postoperatively (p > or = 0.05). Postoperative hair-washing resulted in no increase in incision infection scores or decrease in HRQOL scores when compared to no hair-washing in patients experiencing craniotomy.

Fidelity considerations in translational research: Eating As Treatment - a stepped wedge, randomised controlled trial of a dietitian delivered behaviour change counselling intervention for head and neck cancer patients undergoing radiotherapy.

PubMed

Beck, Alison Kate; Baker, Amanda; Britton, Ben; Wratten, Chris; Bauer, Judith; Wolfenden, Luke; Carter, Gregory

2015-10-15

The confidence with which researchers can comment on intervention efficacy relies on evaluation and consideration of intervention fidelity. Accordingly, there have been calls to increase the transparency with which fidelity methodology is reported. Despite this, consideration and/or reporting of fidelity methods remains poor. We seek to address this gap by describing the methodology for promoting and facilitating the evaluation of intervention fidelity in The EAT (Eating As Treatment) project: a multi-site stepped wedge randomised controlled trial of a dietitian delivered behaviour change counselling intervention to improve nutrition (primary outcome) in head and neck cancer patients undergoing radiotherapy. In accordance with recommendations from the National Institutes of Health Behaviour Change Consortium Treatment Fidelity Workgroup, we sought to maximise fidelity in this stepped wedge randomised controlled trial via strategies implemented from study design through to provider training, intervention delivery and receipt. As the EAT intervention is designed to be incorporated into standard dietetic consultations, we also address unique challenges for translational research. We offer a strong model for improving the quality of translational findings via real world application of National Institutes of Health Behaviour Change Consortium recommendations. Greater transparency in the reporting of behaviour change research is an important step in improving the progress and quality of behaviour change research. ACTRN12613000320752 (Date of registration 21 March 2013).

Double-Sided Wedge Model For Retreating Subduction Zones: Applications to the Apenninic and Hellenic Subduction Zones (Invited)

NASA Astrophysics Data System (ADS)

Brandon, M. T.; Willett, S.; Rahl, J. M.; Cowan, D. S.

2009-12-01

We propose a new model for the evolution of accreting wedges at retreating subduction zones. Advance and retreat refer to the polarity of the velocity of the overriding plate with respect to subduction zone. Advance indicates a velocity toward the subduction zone (e.g., Andes) and retreat, away from the subduction zone (e.g. Apennines, Crete). The tectonic mode of a subduction zone, whether advancing or retreating, is a result of both the rollback of the subducting plate and the absolute motion of the overriding plate. The Hellenic and Apenninic wedges are both associated with retreating subduction zones. The Hellenic wedge has been active for about 100 Ma, whereas the Apenninic wedge has been active for about 30 Ma. Comparison of maximum metamorphic pressures for exhumed rocks in these wedges (25 and 30 km, respectively) with the maximum thickness of the wedges at present (30 and 35 km, respectively) indicates that each wedge has maintained a relatively steady size during its evolution. This conclusion is based on the constraint that both frictional and viscous wedges are subject to the constraint of a steady wedge taper, so that thickness and width are strongly correlated. Both wedges show clear evidence of steady accretion during their full evolution, with accretionary fluxes of about 60 and 200 km2 Ma-1. These wedges also both show steady drift of material from the front to the rear of the wedge, with horizontal shortening dominating in the front of the wedge, and horizontal extension within the back of the wedge. We propose that these wedges represent two back-to-back wedges, with a convergent wedge on the leading side (proside), and a divergent wedge on the trailing side (retroside). In this sense, the wedges are bound by two plates. The subducting plate is familiar. It creates a thrust-sense traction beneath the proside of the wedge. The second plate is an “educting” plate, which is creates a normal-sense traction beneath the retroside of the wedge. The educting plate underlies the Tyrrenhian Sea west of the Apennines and the Cretean Sea north of Crete. The stretched crust that overlies this plate represents highly thinned wedge material that has been removed or decreted from the wedge. This decretion process accounts for the mean motion within the wedge, from pro to retro side, and the pervasive thinning within the retroside. It also explains how these wedges are able to maintain a steady wedge size with time. An important prediction of this model is that different deformational styles, involving thickening and thinning, can occur within the same tectonics setting. This is in contrast the widely cited idea that tectonic thinning is a late- or post-orogenic process.

A Tortuous Process of Surgical Treatment for a Large Calcified Chronic Subdural Hematoma.

PubMed

Li, Huan; Mao, Xiang; Tao, Xiao-Gang; Li, Jing-Sheng; Liu, Bai-Yun; Wu, Zhen

2017-12-01

Calcified chronic subdural hematoma (CCSDH) is a rare disease for which no standard approach to treatment has been established. Reports covering both burr hole trepanation and craniotomy for CCSDH are rare. Furthermore, infection of CCSDH after the burr hole trepanation has not been reported in the literature. A 61-year-old man presented with left frontotemporoparietal CCSDH demonstrated on computed tomography (CT) scan. The patient underwent 2 separate burr hole trepanations with intraoperative irrigation and postoperative drainage. These procedures led to infection of the CCSDH. The patient eventually underwent an open craniotomy to provide complete removal of the hematoma. Owing to the complex contents of a CCSDH, burr hole trepanation cannot adequately drain the hematoma or relieve the mass effect. Craniotomy is a much more reliable approach for achieving complete resection of a CCSDH. Copyright © 2017 Elsevier Inc. All rights reserved.

Epidural Hematoma Complication after Rapid Chronic Subdural Hematoma Evacuation: A Case Report.

PubMed

Akpinar, Aykut; Ucler, Necati; Erdogan, Uzay; Yucetas, Cem Seyho

2015-07-06

Chronic subdural hematoma generally occurs in the elderly. After chronic subdural hematoma evacuation surgery, the development of epidural hematoma is a very rare entity. We report the case of a 41-year-old man with an epidural hematoma complication after chronic subdural hematoma evacuation. Under general anesthesia, the patient underwent a large craniotomy with closed system drainage performed to treat the chronic subdural hematoma. After chronic subdural hematoma evacuation, there was epidural leakage on the following day. Although trauma is the most common risk factor in young CSDH patients, some other predisposing factors may exist. Intracranial hypotension can cause EDH. Craniotomy and drainage surgery can usually resolve the problem. Because of rapid dynamic intracranial changes, epidural leakages can occur. A large craniotomy flap and silicone drainage in the operation area are key safety points for neurosurgeons and hydration is essential.

Transport and optical properties of c-axis oriented wedge shaped GaN nanowall network grown by molecular beam epitaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhasker, H. P.; Dhar, S.; Thakur, Varun

2014-02-21

The transport and optical properties of wedge-shaped nanowall network of GaN grown spontaneously on cplane sapphire substrate by Plasma-Assisted Molecular Beam Epitaxy (PAMBE) show interesting behavior. The electron mobility at room temperature in these samples is found to be orders of magnitude higher than that of a continuous film. Our study reveals a strong correlation between the mobility and the band gap in these nanowall network samples. However, it is seen that when the thickness of the tips of the walls increases to an extent such that more than 70% of the film area is covered, it behaves close tomore » a flat sample. In the sample with lower surface coverage (≈40% and ≈60%), it was observed that the conductivity, mobility as well as the band gap increase with the decrease in the average tip width of the walls. Photoluminescence (PL) experiments show a strong and broad band edge emission with a large (as high as ≈ 90 meV) blue shift, compared to that of a continuous film, suggesting a confinement of carriers on the top edges of the nanowalls. The PL peak width remains wide at all temperatures suggesting the existence of a high density of tail states at the band edge, which is further supported by the photoconductivity result. The high conductivity and mobility observed in these samples is believed to be due to a “dissipation less” transport of carriers, which are localized at the top edges (edge states) of the nanowalls.« less

A prospective, randomized, double-blind, and multicenter trial of prophylactic effects of ramosetronon postoperative nausea and vomiting (PONV) after craniotomy: comparison with ondansetron

PubMed Central

2014-01-01

Background Craniotomy patients have a high incidence of postoperative nausea and vomiting (PONV). This prospective, randomized, double-blind, multi-center study was performed to evaluate the efficacy of prophylactic ramosetron in preventing PONV compared with ondansetron after elective craniotomy in adult patients. Methods A total of 160 American Society of Anesthesiologists physical status I–II patients aged 19–65 years who were scheduled to undergo elective craniotomy for various intracranial lesions were enrolled in this study. All patients received total intravenous anesthesia (TIVA) with propofol and remifentanil. Patients were randomly allocated into three groups to receive ondansetron (4 mg; group A, n  =  55), ondansetron (8 mg; group B, n  =  54), or ramosetron (0.3 mg; group C, n  =  51) intravenously at the time of dural closure. The incidence of PONV, the need for rescue antiemetics, pain score, patient-controlled analgesia (PCA) consumption, and adverse events were recorded 48 h postoperatively. Results Among the initial 160 patients, 127 completed the study and were included in the final analysis. The incidences of PONV were lower (nausea, 14% vs. 59% and 41%, respectively; P  <  0.001; vomiting, P  =  0.048) and the incidence of complete response was higher (83% vs. 37% and 59%, respectively; P  <  0.001) in group C than in groups A and B at 48 h postoperatively. There were no significant differences in the incidence of PONV or need for rescue antiemetics 0–2 h postoperatively, but significant differences were observed in the incidence of PONV and complete response among the three groups 2–48 h postoperatively. No statistically significant intergroup differences were observed in postoperative pain, PCA consumption, or adverse events. Conclusion Intravenous administration of ramosetron at 0.3 mg reduced the incidence of PONV and rescue antiemetic requirement in craniotomy patients. Ramosetron at 0.3 mg was more effective than ondansetron at 4 or 8 mg for preventing PONV in adult craniotomy patients. Trial registration Clinical Research Information Service (CRiS) Identifier: KCT0000320. Registered 9 January 2012. PMID:25104916

P-Wave to Rayleigh-wave conversion coefficients for wedge corners; model experiments

USGS Publications Warehouse

Gangi, A.F.; Wesson, R.L.

1978-01-01

An analytic solution is not available for the diffraction of elastic waves by wedges; however, numerical solutions of finite-difference type are available for selected wedge angles. The P- to Rayleigh-wave conversion coefficients at wedge tips have been measured on two-dimensional seismic models for stress-free wedges with wedge angles, ??0, of 10, 30, 60, 90 and 120??. The conversion coefficients show two broad peaks and a minimum as a function of the angle between the wedge face and the direction of the incident P-wave. The minimum occurs for the P wave incident parallel to the wedge face and one maximum is near an incidence angle of 90?? to the wedge face. The amplitude of this maximum, relative to the other, decreases as the wedge angle increases. The asymmetry of the conversion coefficients, CPR(??; ??0), relative to parallel incidence (?? = 0) increases as the wedge angle increases. The locations of the maxima and the minimum as well as the asymmetry can be explained qualitatively. The conversion coefficients are measured with an accuracy of ??5% in those regions where there are no interfering waves. A comparison of the data for the 10?? wedge with the theoretical results for a half plane (0?? wedge) shows good correlation. ?? 1978.

Care of Pediatric Neurosurgical Patients in Iraq in 2007: Clinical and Ethical Experience of a Field Hospital

DTIC Science & Technology

2010-09-01

epidural abscess from a prior craniotomy for trauma at our facility. Patient Care Of the 42 pediatric patients seen in consultation, 28 required surgical...bifrontal craniotomy for the repair of an anterior skull base inju- ry (3 cases), decompressive craniectomy (5 cases), local debridement and wound closure...for PHI (10 cases), ICP monitoring only (4 cases), spinal instrumentation (1 case), spinal exploration/debridement with lumbar drainage for

Von Hippel-Lindau Disease: A Rare Familiar Multi-System Disorder and the Impact of the Clinical Nurse Specialist

DTIC Science & Technology

1993-01-01

would undergo removal of both adrenal glands, the renal cell carcinomas, a cholecystectomy and a choledochoduodenostomy for biliary drainage . The...bleeding, renal failure, and pancreatitis. After recovery, a craniotomy would be done to remove the hemangioblastoma that had been bleeding. The...analgesia. After a three month convalescence, the patient had a craniotomy and was home within a week. The patient’s siblings have all had negative eye

Use of the Abdominal Aortic Tourniquet for Hemorrhage Control

DTIC Science & Technology

2013-10-01

simulate an epidural hematoma) using a bone drill to access the epidural space via a craniotomy and then use a small bladder and fill with fluid. We would...external pressure transducer and CSF drainage system. The catheter will be sutured in place and a nonocclusive dressing applied. The catheter will...diameter in relation to ICP. Craniotomy . A midline incision from the level of lateral canthi to 4-7cm past the external occipital protuberance will be

Evaluation of SOCOM Wireless Monitor in Trauma Patients

DTIC Science & Technology

2016-02-01

the need for craniotomy in the absence of neurologic change. J Trauma Acute Care Surg 2013 Apr;74(4):967-75. 35) Thorson CM, Van Haren RM, Ryan...Guarch GA, Hanna M, Allen CJ, Ray JJ, Schulman CI, Proctor KG, Sleeman D, Namias N: Need for percutaneous drainage after cholecystectomy is higher in...Repeat head CT after minimal brain injury predicts need for craniotomy in absence of neurologic change. a. Presented at 71rst Annual Meeting of

Should epidural drain be recommended after supratentorial craniotomy for epileptic patients?

PubMed

Guangming, Zhang; Huancong, Zuo; Wenjing, Zhou; Guoqiang, Chen; Xiaosong, Wang

2009-08-01

ED was once and is still commonly applied to prevent mainly EH and subgaleal CSF collection. We designed this study to observe if ED could decrease the incidence and volume of EH and subgaleal CSF collection after supratentorial craniotomy in epileptic patients. Three hundred forty-two epileptic patients were divided into 2 groups according to their first craniotomy date (group 1 in odd date and group 2 in even date). Patients in group 1 had ED and those in group 2 had no ED. The patient numbers and volumes of EH and subgaleal CSF collections in both groups were recorded and statistically analyzed. There were 22 EHs in group 1 and 20 EHs in group 2. There were 11 and 10 subgaleal CSF collections in groups 1 and 2, respectively. The average volume of EH was 13.5 +/- 8.12 and 14.65 +/- 7.72 mL in groups 1 and 2, respectively. The average volume of subgaleal CSF collection was 42.76 +/- 12.09 and 43.75 +/- 11.44 mL in groups 1 and 2, respectively. There were no statistical differences in the incidence and average volume of EH and subgaleal CSF collection between the 2 groups. ED cannot decrease the incidence and volume of EH and subgaleal CSF collection. ED should not be recommended after supratentorial epileptic craniotomy.

[Risk factors for surgical site infections in patients undergoing craniotomy].

PubMed

Cha, Kyeong-Sook; Cho, Ok-Hee; Yoo, So-Yeon

2010-04-01

The objectives of this study were to determine the prevalence, incidence, and risk factors for postoperative surgical site infections (SSIs) after craniotomy. This study was a retrospective case-control study of 103 patients who had craniotomies between March 2007 and December 2008. A retrospective review of prospectively collected databases of consecutive patients who underwent craniotomy was done. SSIs were defined by using the Centers for Disease Control criteria. Twenty-six cases (infection) and 77 controls (no infection) were matched for age, gender and time of surgery. Descriptive analysis, t-test, X(2)-test and logistic regression analyses were used for data analysis. The statistical difference between cases and controls was significant for hospital length of stay (>14 days), intensive care unit stay more than 15 days, Glasgrow Coma Scale (GCS) score (< or = 7 days), extra-ventricular drainage and coexistent infection. Risk factors were identified by logistic regression and included hospital length of stay of more than 14 days (odds ratio [OR]=23.39, 95% confidence interval [CI]=2.53-216.11) and GCS score (< or = 7 scores) (OR=4.71, 95% CI=1.64-13.50). The results of this study show that patients are at high risk for infection when they have a low level of consciousness or their length hospital stay is long term. Nurses have to take an active and continuous approach to infection control to help with patients having these risk factors.

Efficacy and safety of key hole craniotomy for the evacuation of spontaneous cerebellar hemorrhage.

PubMed

Tokimura, Hiroshi; Tajitsu, Kenichiro; Taniguchi, Ayumi; Yamahata, Hitoshi; Tsuchiya, Masahiro; Takayama, Kenji; Shinsato, Tomomi; Arita, Kazunori

2010-01-01

The efficacy and safety of cerebellar hemorrhage evacuation by key hole craniotomy and the importance of thorough evacuation and irrigation of the hematoma in the fourth ventricle to resolve obstructive hydrocephalus were assessed in 23 patients with spontaneous cerebellar hemorrhage (SCH) greater than 3 cm or with brainstem compression and hydrocephalus. A 5-cm elongated S-shaped scalp incision was made, and a 3-cm key hole craniotomy was performed over a cerebellar convexity area. The hematoma was immediately evacuated through a small corticotomy. The hematoma in the fourth ventricle was gently removed through the hematoma cavity, followed by thorough saline irrigation to release obstructive hydrocephalus. Patients classified retrospectively into favorable and poor outcome groups using the Glasgow Outcome Scale (GOS) scores of 4-5 vs. 1-3 showed significant differences with respect to the preoperative Glasgow Coma Scale, hematoma size and volume, and brainstem compression. Only 2 of the 23 patients required ventricular drainage and no postoperative complications were recorded. Patients treated by experienced and inexperienced surgeons showed no significant differences in the hematoma evacuation rate, postoperative GOS, and interval from skin incision to start of hematoma evacuation. Our simplified method of key hole craniotomy to treat SCH was less invasive but easy to perform, as even inexperienced neurosurgeons could obtain good surgical results. Thorough cleaning of the fourth ventricle minimized the necessity for ventricular drainage.

Successful Insular Glioma Removal in a Deaf Signer Patient During an Awake Craniotomy Procedure.

PubMed

Metellus, Philippe; Boussen, Salah; Guye, Maxime; Trebuchon, Agnes

2017-02-01

Resection of tumors located within the insula of the dominant hemisphere represents a technical challenge because of the complex anatomy, including the surrounding vasculature, and the relationship to functional (motor and language) structures. We report here the case of a successful resection of a left insular glioma in a native deaf signer during an awake craniotomy. The patient, a congenitally deaf right-handed patient who is a native user of sign language, presented with a seizure 1 week before he was referred to our department. Magnetic resonance imaging revealed a left heterogeneous insular tumor enhanced after intravenous gadolinium infusion. Because of its deep and dominant hemisphere location, an awake craniotomy was decided. The patient was evaluated intraoperatively using object naming, text reading, and sign repetition tasks. An isolated inferior frontal gyrus site evoked repeated object naming errors. A transopercular parietal approach was performed and allowed the successful removal of the tumor under direct electric stimulation and electrocorticography. To our knowledge, this is the first report of successful removal of a left insular tumor without any functional sequelae in a native deaf signer using intraoperative direct cerebral stimulation during an awake craniotomy. The methodology used also provides the first evidence of the actual anatomo-functional organization of language in deaf signers. Copyright © 2016 Elsevier Inc. All rights reserved.

Orbitopterional Craniotomy Resection of Pediatric Suprasellar Craniopharyngioma.

PubMed

LeFever, Devon; Storey, Chris; Guthikonda, Bharat

2018-04-01

The orbitopterional approach provides an excellent combination of basal access and suprasellar access. This approach also allows for less brain retraction when resecting larger suprasellar tumors that are more superiorly projecting due to a more frontal and inferior trajectory. In this operative video, the authors thoroughly detail an orbitopterional craniotomy utilizing a one-piece modified orbitozygomatic technique. This technique involves opening the craniotomy through a standard pterional incision. The craniotomy is performed using the standard three burr holes of a pterional approach; however, the osteotomy is extended anteriorly through the frontal process of the zygomatic bone as well as through the supraorbital rim. In this operative video atlas, the authors illustrate the operative anatomy, as well as surgical strategy and techniques to resect a large suprasellar craniopharyngioma in a 4-year-old male. Other reasonable approach options for a lesion of this size would include a standard pterional approach, a supraorbital approach, or expanded endoscopic transsphenoidal approach. The lesion was quite high and thus, the supraorbital approach may confine access to the superior portion of the tumor. While recognizing that some groups may have chosen the endoscopic expanded transsphenoidal approach for this lesion, the authors describe more confidence in achieving the goal of a safe and maximal resection with the orbitopterional approach. The link to the video can be found at: https://youtu.be/eznsK16BzR8 .

Chronic Subdural Hematoma Infected by Propionibacterium Acnes: A Case Report

PubMed Central

Yamamoto, Shusuke; Asahi, Takashi; Akioka, Naoki; Kashiwazaki, Daina; Kuwayama, Naoya; Kuroda, Satoshi

2015-01-01

We present a very rare case of a patient with an infected subdural hematoma due to Propionibacterium acnes. A 63-year-old male complained of dizziness and was admitted to our hospital. He had a history of left chronic subdural hematoma due to a traffic accident, which had been conservatively treated. Physical, neurological and laboratory examinations revealed no definite abnormality. Plain CT scan demonstrated a hypodense crescentic fluid collection over the surface of the left cerebral hemisphere. The patient was diagnosed with chronic subdural hematoma and underwent burr hole surgery three times and selective embolization of the middle meningeal artery, but the lesion easily recurred. Repeated culture examinations of white sedimentation detected P. acnes. Therefore, he underwent craniotomy surgery followed by intravenous administration of antibiotics. The infected subdural hematoma was covered with a thick, yellowish outer membrane, and the large volume of pus and hematoma was removed. However, the lesion recurred again and a low-density area developed in the left frontal lobe. Craniotomy surgery was performed a second time, and two Penrose drainages were put in both the epidural and subdural spaces. Subsequently, the lesions completely resolved and he was discharged without any neurological deficits. Infected subdural hematoma may be refractory to burr hole surgery or craniotomy alone, in which case aggressive treatment with craniotomy and continuous drainage should be indicated before the brain parenchyma suffers irreversible damage. PMID:25759659

Usefulness of an Osteotomy Template for Skull Tumorectomy and Simultaneous Skull Reconstruction.

PubMed

Oji, Tomito; Sakamoto, Yoshiaki; Miwa, Tomoru; Nakagawa, Yu; Yoshida, Kazunari; Kishi, Kazuo

2016-09-01

Simultaneous tumor resection and cranioplasty with hydroxyapatite osteosynthesis are sometimes necessary in patients of skull neoplasms or skull-invasive tumors. However, the disadvantage of simultaneous surgery is that mismatches often occur between the skull defect and the hydroxyapatite implant. To solve this problem, the authors developed a customized template for designing the craniotomy line. Before each operation, the craniotomy design was discussed with a neurosurgeon. Based on the discussion, 2 hydroxyapatite implants were customized for each patient on the basis of models prepared using computed tomography data. The first implant was an onlay template for the preoperative cranium, which was customized for designing the osteotomy line. The other implant was used for the skull defect. Using the template, the osteotomy line was drawn along the template edge, osteotomy was performed along this line, and the implant was placed in the skull defect. This technique was performed in 3 patients. No implant or defect trimming was required in any patient, good cosmetic outcomes were noted in all patients, and no complications occurred. Use of predesigned hydroxyapatite templates for craniotomy during simultaneous skull tumor resection and cranioplasty has some clinical advantages: the precise craniotomy line can be designed, the implant and skull defect fit better and show effective osteoconduction, trimming of the implant or defect is minimized, and the operation time is shortened.

High Performance Seed Based Optical Computing.

DTIC Science & Technology

1998-05-01

distances of the lenses must be large to allow space for elements needed for align- ment, such as an afocal pair, a pair of wedges , and a pellicle...minute wedges . Each of the wedges can be rotated independently to bring the spots onto the proper win- 78 dows. Because the wedges have such a small... wedge angle, a large rotation of the wedges causes only a small movement of the spots; a 180 degree rotation of one wedge moves the spots by 74 U\\m

Inclined indentation of smooth wedge in rock mass

NASA Astrophysics Data System (ADS)

Chanyshev, AI; Podyminogin, GM; Lukyashko, OA

2018-03-01

The article focuses on the inclined rigid wedge indentation into a rigid-plastic half-plane of rocks with the Mohr–Coulomb-Mohr plasticity. The limiting loads on different sides of the wedge are determined versus the internal friction angle, cohesion and wedge angle. It is shown that when the force is applied along the symmetry axis of the wedge, the zone of plasticity is formed only on one wedge side. In order to form the plasticity zone on both sides of the wedge, it is necessary to apply the force asymmetrically relative to the wedge symmetry axis. An engineering solution for the asymmetrical case implementation is suggested.

Episodic growth of fold-thrust belts: Insights from Finite Element Modelling

NASA Astrophysics Data System (ADS)

Yang, Xiaodong; Peel, Frank J.; Sanderson, David J.; McNeill, Lisa C.

2017-09-01

The sequential development of a fold-thrust belt was investigated using 2D Finite Element Modelling (FEM). The new model results show that a thrust system is typically composed of three distinct regions: the thrust wedge, pre-wedge, and undeformed region. The thrust wedge involves growth that repeats episodically and cyclically. A cycle of wedge building starts as frontal accretion occurs, which is accompanied by a rapid increase in wedge width reducing the taper angle below critical. In response to this, the wedge interior (tracked here by the 50 m displacement position) rapidly propagates forwards into a region of incipient folding. The taper angle progressively increases until it obtains a constant apparent critical value (∼10°). During this period, the wedge experiences significant shortening after a new thrust initiates at the failure front, leading to a decrease in wedge width. Successive widening of the wedge and subsequent shortening and thrusting maintain a reasonably constant taper angle. The fold-thrust belt evolves cyclically, through a combination of rapid advancement of the wedge and subsequent gradual, slow wedge growth. The new model results also highlights that there is clear, although minor, deformation (0-10 m horizontal displacement) in front of the thrust wedge.

Observation of the dispersion of wedge waves propagating along cylinder wedge with different truncations by laser ultrasound technique

NASA Astrophysics Data System (ADS)

Jia, Jing; Zhang, Yu; Han, Qingbang; Jing, Xueping

2017-10-01

The research focuses on study the influence of truncations on the dispersion of wedge waves propagating along cylinder wedge with different truncations by using the laser ultrasound technique. The wedge waveguide models with different truncations were built by using finite element method (FEM). The dispersion curves were obtained by using 2D Fourier transformation method. Multiple mode wedge waves were observed, which was well agreed with the results estimated from Lagasse's empirical formula. We established cylinder wedge with radius of 3mm, 20° and 60°angle, with 0μm, 5μm, 10μm, 20μm, 30μm, 40μm, and 50μm truncations, respectively. It was found that non-ideal wedge tip caused abnormal dispersion of the mode of cylinder wedge, the modes of 20° cylinder wedge presents the characteristics of guide waves which propagating along hollow cylinder as the truncation increasing. Meanwhile, the modes of 60° cylinder wedge with truncations appears the characteristics of guide waves propagating along hollow cylinder, and its mode are observed clearly. The study can be used to evaluate and detect wedge structure.

Comparison of propofol pharmacokinetic and pharmacodynamic models for awake craniotomy: A prospective observational study.

PubMed

Soehle, Martin; Wolf, Christina F; Priston, Melanie J; Neuloh, Georg; Bien, Christian G; Hoeft, Andreas; Ellerkmann, Richard K

2015-08-01

Anaesthesia for awake craniotomy aims for an unconscious patient at the beginning and end of surgery but a rapidly awakening and responsive patient during the awake period. Therefore, an accurate pharmacokinetic/pharmacodynamic (PK/PD) model for propofol is required to tailor depth of anaesthesia. To compare the predictive performances of the Marsh and the Schnider PK/PD models during awake craniotomy. A prospective observational study. Single university hospital from February 2009 to May 2010. Twelve patients undergoing elective awake craniotomy for resection of brain tumour or epileptogenic areas. Arterial blood samples were drawn at intervals and the propofol plasma concentration was determined. The prediction error, bias [median prediction error (MDPE)] and inaccuracy [median absolute prediction error (MDAPE)] of the Marsh and the Schnider models were calculated. The secondary endpoint was the prediction probability PK, by which changes in the propofol effect-site concentration (as derived from simultaneous PK/PD modelling) predicted changes in anaesthetic depth (measured by the bispectral index). The Marsh model was associated with a significantly (P = 0.05) higher inaccuracy (MDAPE 28.9 ± 12.0%) than the Schnider model (MDAPE 21.5 ± 7.7%) and tended to reach a higher bias (MDPE Marsh -11.7 ± 14.3%, MDPE Schnider -5.4 ± 20.7%, P = 0.09). MDAPE was outside of accepted limits in six (Marsh model) and two (Schnider model) of 12 patients. The prediction probability was comparable between the Marsh (PK 0.798 ± 0.056) and the Schnider model (PK 0.787 ± 0.055), but after adjusting the models to each individual patient, the Schnider model achieved significantly higher prediction probabilities (PK 0.807 ± 0.056, P = 0.05). When using the 'asleep-awake-asleep' anaesthetic technique during awake craniotomy, we advocate using the PK/PD model proposed by Schnider. Due to considerable interindividual variation, additional monitoring of anaesthetic depth is recommended. ClinicalTrials.gov identifier: NCT 01128465.

Comparison of dexmedetomidine and propofol for conscious sedation in awake craniotomy: a prospective, double-blind, randomized, and controlled clinical trial.

PubMed

Shen, She-liang; Zheng, Jia-yin; Zhang, Jun; Wang, Wen-yuan; Jin, Tao; Zhu, Jing; Zhang, Qi

2013-11-01

It has been reported that dexmedetomidine (DEX) can be used for conscious sedation in awake craniotomy, but few data exist to compare DEX versus propofol (PRO). To compare the efficacy and safety of DEX versus PRO for conscious sedation in awake craniotomy. Thirty patients of American Society of Anesthesiologists grade I-II scheduled for awake craniotomy, were randomized into 2 groups each containing 15 subjects. Group D received DEX and group P received PRO. Two minutes after tracheal intubation (T1), PRO (target plasma concentration) was titrated down to 1 to 4 µg/mL in group P. In group D, PRO was discontinued and DEX was administered 1.0 µg/kg followed by a maintenance dose of 0.2 to 0.7 µg/kg/h. The surgeon preset the anticipated awake point-in-time (T0) preoperatively. Ten minutes before T0 (T3), DEX was titrated down to 0.2 µg/kg/h in group D, PRO was discontinued and normal saline (placebo) 5 mL/h was infused in group P. Arousal time, quality of revival and adverse events during the awake period, degree of satisfaction from surgeons and patients were recorded. Arousal time was significantly shorter in group D than in group P (P < .001). The quality of revival during the awake period in group D was similar to that of group P (P = .68). The degree of satisfaction of surgeons was significantly higher in group D than in group P (P < .001), but no difference was found between the 2 groups with respect to patient satisfaction (P = .80). There was no difference between the 2 groups in the incidence of adverse events during the awake period (P > .05). Either DEX or PRO can be effectively and safely used for conscious sedation in awake craniotomy. Comparing the two, DEX produced a shorter arousal time and a higher degree of surgeon satisfaction.

Awake craniotomy for gliomas in a high-field intraoperative magnetic resonance imaging suite: analysis of 42 cases.

PubMed

Maldaun, Marcos V C; Khawja, Shumaila N; Levine, Nicholas B; Rao, Ganesh; Lang, Frederick F; Weinberg, Jeffrey S; Tummala, Sudhakar; Cowles, Charles E; Ferson, David; Nguyen, Anh-Thuy; Sawaya, Raymond; Suki, Dima; Prabhu, Sujit S

2014-10-01

The object of this study was to describe the experience of combining awake craniotomy techniques with high-field (1.5 T) intraoperative MRI (iMRI) for tumors adjacent to eloquent cortex. From a prospective database the authors obtained and evaluated the records of all patients who had undergone awake craniotomy procedures with cortical and subcortical mapping in the iMRI suite. The integration of these two modalities was assessed with respect to safety, operative times, workflow, extent of resection (EOR), and neurological outcome. Between February 2010 and December 2011, 42 awake craniotomy procedures using iMRI were performed in 41 patients for the removal of intraaxial tumors. There were 31 left-sided and 11 right-sided tumors. In half of the cases (21 [50%] of 42), the patient was kept awake for both motor and speech mapping. The mean duration of surgery overall was 7.3 hours (range 4.0-13.9 hours). The median EOR overall was 90%, and gross-total resection (EOR ≥ 95%) was achieved in 17 cases (40.5%). After viewing the first MR images after initial resection, further resection was performed in 17 cases (40.5%); the mean EOR in these cases increased from 56% to 67% after further resection. No deficits were observed preoperatively in 33 cases (78.5%), and worsening neurological deficits were noted immediately after surgery in 11 cases (26.2%). At 1 month after surgery, however, worsened neurological function was observed in only 1 case (2.3%). There was a learning curve with regard to patient positioning and setup times, although it did not adversely affect patient outcomes. Awake craniotomy can be safely performed in a high-field (1.5 T) iMRI suite to maximize tumor resection in eloquent brain areas with an acceptable morbidity profile at 1 month.

Incidence of intraoperative seizures during motor evoked potential monitoring in a large cohort of patients undergoing different surgical procedures.

PubMed

Ulkatan, Sedat; Jaramillo, Ana Maria; Téllez, Maria J; Kim, Jinu; Deletis, Vedran; Seidel, Kathleen

2017-04-01

OBJECTIVE The purpose of this study was to investigate the incidence of seizures during the intraoperative monitoring of motor evoked potentials (MEPs) elicited by electrical brain stimulation in a wide spectrum of surgeries such as those of the orthopedic spine, spinal cord, and peripheral nerves, interventional radiology procedures, and craniotomies for supra- and infratentorial tumors and vascular lesions. METHODS The authors retrospectively analyzed data from 4179 consecutive patients who underwent surgery or an interventional radiology procedure with MEP monitoring. RESULTS Of 4179 patients, only 32 (0.8%) had 1 or more intraoperative seizures. The incidence of seizures in cranial procedures, including craniotomies and interventional neuroradiology, was 1.8%. In craniotomies in which transcranial electrical stimulation (TES) was applied to elicit MEPs, the incidence of seizures was 0.7% (6/850). When direct cortical stimulation was additionally applied, the incidence of seizures increased to 5.4% (23/422). Patients undergoing craniotomies for the excision of extraaxial brain tumors, particularly meningiomas (15 patients), exhibited the highest risk of developing an intraoperative seizure (16 patients). The incidence of seizures in orthopedic spine surgeries was 0.2% (3/1664). None of the patients who underwent surgery for conditions of the spinal cord, neck, or peripheral nerves or who underwent cranial or noncranial interventional radiology procedures had intraoperative seizures elicited by TES during MEP monitoring. CONCLUSIONS In this largest such study to date, the authors report the incidence of intraoperative seizures in patients who underwent MEP monitoring during a wide spectrum of surgeries such as those of the orthopedic spine, spinal cord, and peripheral nerves, interventional radiology procedures, and craniotomies for supra- and infratentorial tumors and vascular lesions. The low incidence of seizures induced by electrical brain stimulation, particularly short-train TES, demonstrates that MEP monitoring is a safe technique that should not be avoided due to the risk of inducing seizures.

Degradation and stabilization of ice wedges: Implications for assessing risk of thermokarst in northern Alaska

NASA Astrophysics Data System (ADS)

Kanevskiy, Mikhail; Shur, Yuri; Jorgenson, Torre; Brown, Dana R. N.; Moskalenko, Nataliya; Brown, Jerry; Walker, Donald A.; Raynolds, Martha K.; Buchhorn, Marcel

2017-11-01

Widespread degradation of ice wedges has been observed during the last decades in numerous areas within the continuous permafrost zone of Eurasia and North America. To study ice-wedge degradation, we performed field investigations at Prudhoe Bay and Barrow in northern Alaska during 2011-2016. In each study area, a 250-m transect was established with plots representing different stages of ice-wedge degradation/stabilization. Field work included surveying ground- and water-surface elevations, thaw-depth measurements, permafrost coring, vegetation sampling, and ground-based LiDAR scanning. We described cryostratigraphy of frozen soils and stable isotope composition, analyzed environmental characteristics associated with ice-wedge degradation and stabilization, evaluated the vulnerability and resilience of ice wedges to climate change and disturbances, and developed new conceptual models of ice-wedge dynamics that identify the main factors affecting ice-wedge degradation and stabilization and the main stages of this quasi-cyclic process. We found significant differences in the patterns of ice-wedge degradation and stabilization between the two areas, and the patterns were more complex than those previously described because of the interactions of changing topography, water redistribution, and vegetation/soil responses that can interrupt or reinforce degradation. Degradation of ice wedges is usually triggered by an increase in the active-layer thickness during exceptionally warm and wet summers or as a result of flooding or disturbance. Vulnerability of ice wedges to thermokarst is controlled by the thickness of the intermediate layer of the upper permafrost, which overlies ice wedges and protects them from thawing. In the continuous permafrost zone, degradation of ice wedges rarely leads to their complete melting; and in most cases wedges eventually stabilize and can then resume growing, indicating a somewhat cyclic and reversible process. Stabilization of ice wedges after their partial degradation makes them better protected than before degradation because the intermediate layer is usually 2 to 3 times thicker on top of stabilized ice wedges than on top of initial ice wedges in undisturbed conditions. As a result, the likelihood of formation of large thaw lakes in the continuous permafrost zone triggered by ice-wedge degradation alone is very low.

Use of Performance Measures to Evaluate, Document Competence and Deterioration of Advanced Surgical Skills Exposure for Trauma (ASSET) Surgical Skills

DTIC Science & Technology

2015-03-01

71(2):193- 7. 13. Lobel DA, Elder JB, Schirmer CM, Bowyer MW, Rezai AR. A novel craniotomy simulator provides a validated method to enhance...MW, Rezai AR. A novel craniotomy simulator provides a validated method to enhance education in the management of traumatic brain injury...comparisons are significant at pɘ.05 - Wilcoxon matched pairs) A Specialty 0 5 10 15 20 Thoracotomy in ED Repair/ Drainage Hapatic Lacs- Open Neck exploration

Current US Military Operations and Implications for Military Surgical Training

DTIC Science & Technology

2010-11-01

with most procedures encountered except nephrectomy (1.5 proce- dures per resident [PPR]), craniotomy (1.1 PPRs), inferior vena cava injury (1.1 PPRs... craniotomy , IVC injury, duodenal injury, and bladder re- pair. Residents had minimal experience with external fixa- tion of skeletal injury and...vascular injury 3.5 NR Nephrectomy 3.5 1.5 Pancreatic drainage 2.8 1.9 IVC injury 2.4 1.1 Duodenal injury 2.2 0.6 NR, procedure frequency not captured

[Osteomyelitis due to Yokenella regensburgei following craniotomy in an immunocompetent patient].

PubMed

Penagos, Sara Catalina; Gómez, Sebastián; Villa, Pablo; Estrada, Santiago; Agudelo, Carlos Andrés

2015-01-01

The gram-negative bacillus Yokenella regensburgei (of the Enterobacteriaceae family) can be found in groundwater and foodstuffs, as well as the digestive tracts of insects and reptiles. Although it has been isolated from humans since its original description, it has rarely been reported as a cause of infection, and then, only in immunosuppressed patients. We report the first case of post-surgical secondary osteomyelitis due to Y. regensburgei in an immunocompetent woman who had undergone a craniotomy.

One Small Randomly Blinking Dot in an Otherwise Dark Environment: Effects on Visual Cortical Neurons of Kittens.

DTIC Science & Technology

1982-06-23

back onto the tangent screen. A one centimeter oblong craniotomy was drilled, revealing the medial banks of both hemispheres, -2 mm posterior to A-P...zero. A one cm high plastic chamber was cemented to the skull around the craniotomy . After tungsten hooks were used to tear the dura over the medial...stimulus continuously for several weeks. If the kittens were awake for 10 hr per day average then each accumulated about 500 hr opportunity to view the

Epidural Hematoma Complication after Rapid Chronic Subdural Hematoma Evacuation: A Case Report

PubMed Central

Akpinar, Aykut; Ucler, Necati; Erdogan, Uzay; Yucetas, Cem Seyho

2015-01-01

Patient: Male, 41 Final Diagnosis: Healty Symptoms: Headache Medication: — Clinical Procedure: Chronic subdural hematoma Specialty: Neurosurgery Objective: Diagnostic/therapeutic accidents Background: Chronic subdural hematoma generally occurs in the elderly. After chronic subdural hematoma evacuation surgery, the development of epidural hematoma is a very rare entity. Case Report: We report the case of a 41-year-old man with an epidural hematoma complication after chronic subdural hematoma evacuation. Under general anesthesia, the patient underwent a large craniotomy with closed system drainage performed to treat the chronic subdural hematoma. After chronic subdural hematoma evacuation, there was epidural leakage on the following day. Conclusions: Although trauma is the most common risk factor in young CSDH patients, some other predisposing factors may exist. Intracranial hypotension can cause EDH. Craniotomy and drainage surgery can usually resolve the problem. Because of rapid dynamic intracranial changes, epidural leakages can occur. A large craniotomy flap and silicone drainage in the operation area are key safety points for neurosurgeons and hydration is essential. PMID:26147957

[Awake craniotomy. Considerations in special situations].

PubMed

Solera Ruiz, I; Uña Orejón, R; Valero, I; Laroche, F

2013-01-01

Awake craniotomy was the earliest surgical procedure known, and it has become fashionable again. In the past it was used for the surgical management of intractable epilepsy, but nowadays, its indications are increasing, and it is a widely recognized technique for the resection of mass lesions involving the eloquent cortex, and for deep brain stimulation. The procedure is safe, provides excellent results, and saves money and resources. The anesthesiologist should know the principles underlying neuroanesthesia, the technique of scalp blockade, and the sedation protocols, as well as feeling comfortable with advanced airway management. The main anesthetic aim is to keep patients cooperating when required (analgesia-based anesthesia). This review attempts to summarize the most recent evidence from the clinical literature, a long as the number of patients undergoing craniotomies in the awake state are increasing, specifically in the pediatric population. Copyright © 2011 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

Awake craniotomy anesthetic management using dexmedetomidine, propofol, and remifentanil

PubMed Central

Prontera, Andrea; Baroni, Stefano; Marudi, Andrea; Valzania, Franco; Feletti, Alberto; Benuzzi, Francesca; Bertellini, Elisabetta; Pavesi, Giacomo

2017-01-01

Introduction Awake craniotomy allows continuous monitoring of patients’ neurological functions during open surgery. Anesthesiologists have to sedate patients in a way so that they are compliant throughout the whole surgical procedure, nevertheless maintaining adequate analgesia and anxiolysis. Currently, the use of α2-receptor agonist dexmedetomidine as the primary hypnotic–sedative medication is increasing. Methods Nine patients undergoing awake craniotomy were treated with refined monitored anesthesia care (MAC) protocol consisting of a combination of local anesthesia without scalp block, low-dose infusion of dexmedetomidine, propofol, and remifentanil, without the need of airways management. Results The anesthetic protocol applied in our study has the advantage of decreasing the dose of each drug and thus reducing the occurrence of side effects. All patients had smooth and rapid awakenings. The brain remained relaxed during the entire procedure. Conclusion In our experience, this protocol is safe and effective during awake brain surgery. Nevertheless, prospective randomized trials are necessary to confirm the optimal anesthetic technique to be used. PMID:28424537

Awake craniotomy anesthetic management using dexmedetomidine, propofol, and remifentanil.

PubMed

Prontera, Andrea; Baroni, Stefano; Marudi, Andrea; Valzania, Franco; Feletti, Alberto; Benuzzi, Francesca; Bertellini, Elisabetta; Pavesi, Giacomo

2017-01-01

Awake craniotomy allows continuous monitoring of patients' neurological functions during open surgery. Anesthesiologists have to sedate patients in a way so that they are compliant throughout the whole surgical procedure, nevertheless maintaining adequate analgesia and anxiolysis. Currently, the use of α2-receptor agonist dexmedetomidine as the primary hypnotic-sedative medication is increasing. Nine patients undergoing awake craniotomy were treated with refined monitored anesthesia care (MAC) protocol consisting of a combination of local anesthesia without scalp block, low-dose infusion of dexmedetomidine, propofol, and remifentanil, without the need of airways management. The anesthetic protocol applied in our study has the advantage of decreasing the dose of each drug and thus reducing the occurrence of side effects. All patients had smooth and rapid awakenings. The brain remained relaxed during the entire procedure. In our experience, this protocol is safe and effective during awake brain surgery. Nevertheless, prospective randomized trials are necessary to confirm the optimal anesthetic technique to be used.

Tumefactive multiple sclerosis requiring emergency craniotomy: case report and literature review.

PubMed

Munarriz, Pablo M; Castaño-Leon, Ana M; Martinez-Perez, Rafael; Hernandez-Lain, Aurelio; Ramos, Ana; Lagares, Alfonso

2013-01-01

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system, characterized by focal neurological dysfunction with a relapsing and remitting course. Tumor-like presentation of MS (or "tumefactive"/"pseudotumoral" presentation) has been described before with a certain frequency; it consists of a large single plaque (>2cm) with presence of edema and mass effect and it is hard to distinguish from a brain tumor. However, we present a very rare case of a 53-year-old woman with a right temporal mass that turned out to be a MS plaque, who deteriorated within hours (brain herniation with loss of consciousness and unilateral mydriasis) and required an emergency craniotomy. We also present a review of the literature. It appears that only 4 cases of emergency craniotomy/craniectomy required in a patient with a tumor-like MS plaque have been reported before. Copyright © 2012 Sociedad Española de Neurocirugía. Published by Elsevier España. All rights reserved.

Phase Space Exchange in Thick Wedge Absorbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neuffer, David

The problem of phase space exchange in wedge absorbers with ionization cooling is discussed. The wedge absorber exchanges transverse and longitudinal phase space by introducing a position-dependent energy loss. In this paper we note that the wedges used with ionization cooling are relatively thick, so that single wedges cause relatively large changes in beam phase space. Calculation methods adapted to such “thick wedge” cases are presented, and beam phase-space transformations through such wedges are discussed.

Effects of subduction and slab gaps on mantle flow beneath the Lesser Antilles based on observations of seismic anisotropy

NASA Astrophysics Data System (ADS)

Schlaphorst, David; Kendall, J.-Michael; Baptie, Brian; Latchman, Joan L.; Bouin, Marie-Paule

2016-04-01

Subduction is a key process in the formation of continental crust. However, the interaction of the mantle with the subducting slab is not fully understood and varies between subduction zones. The flow geometry and stress patterns influence seismic anisotropy; since anisotropic layers lead to variations in the speed of seismic waves as a function of the direction of wave propagation, mantle flow can be constrained by investigating the structure of these anisotropic layers. In this study we investigate seismic anisotropy in the eastern Greater and the Lesser Antilles along a subduction environment, including the crust and the upper mantle as regions of interest. We use a combination of teleseismic and local events recorded at three-component broadband seismic stations on every major island in the area to observe and distinguish between anisotropy in the crust, the mantle wedge and the sub-slab mantle. Local event delay times (0.21±0.12s) do not increase with depth, indicating a crustal origin and an isotropic mantle wedge. Teleseismic delay times are larger (1.34±0.47s), indicating sub-slab anisotropy. The results suggest trench-parallel mantle flow, with the exception of trench-perpendicular alignment in narrow regions east of Puerto Rico and south of Martinique, suggesting mantle flow through gaps in the slab. This agrees with the continuous northward mantle flow that is caused by the subducting slab proposed by previous studies of that region. We were able to identify a pattern previously unseen by other studies; on St. Lucia a trench-perpendicular trend also indicated by the stations around can be observed. This pattern can be explained by a mantle flow through a gap induced by the subduction of the boundary zone between the North and South American plates. This feature has been proposed for that area using tomographic modelling (van Benthem et al., 2013). It is based on previous results by Wadge & Shepherd (1984), who observed a vertical gap in the Wadati-Benioff zone at that location using a seismicity catalogue from local seismic networks. This work strengthens the argument for that location to be the plate boundary between the North and South American plates.

Nonlinear dynamics of ice-wedge networks and resulting sensitivity to severe cooling events.

PubMed

Plug, L J; Werner, B T

2002-06-27

Patterns of subsurface wedges of ice that form along cooling-induced tension fractures, expressed at the ground surface by ridges or troughs spaced 10 30 m apart, are ubiquitous in polar lowlands. Fossilized ice wedges, which are widespread at lower latitudes, have been used to infer the duration and mean temperature of cold periods within Proterozoic and Quaternary climates, and recent climate trends have been inferred from fracture frequency in active ice wedges. Here we present simulations from a numerical model for the evolution of ice-wedge networks over a range of climate scenarios, based on the interactions between thermal tensile stress, fracture and ice wedges. We find that short-lived periods of severe cooling permanently alter the spacing between ice wedges as well as their fracture frequency. This affects the rate at which the widths of ice wedges increase as well as the network's response to subsequent climate change. We conclude that wedge spacing and width in ice-wedge networks mainly reflect infrequent episodes of rapidly falling ground temperatures rather than mean conditions.

Primary Enlarged Craniotomy in Organized Chronic Subdural Hematomas

PubMed Central

CALLOVINI, Giorgio Maria; BOLOGNINI, Andrea; CALLOVINI, Gemma; GAMMONE, Vincenzo

2014-01-01

The aim of the study is to evaluate the efficacy of craniotomy and membranectomy as initial treatment of organized chronic subdural hematoma (OCSH). We retrospectively reviewed a series of 34 consecutive patients suffering from OCSH, diagnosed by magnetic resonance imaging (MRI) or contrast computer tomography (CCT) in order to establish the degree of organization and determine the intrahematomal architecture. The indication to perform a primary enlarged craniotomy as initial treatment for non-liquefied chronic subdural hematoma (CSDH) with multilayer loculations was based on the hematoma MRI appearance—mostly hyperintense in both T1- and T2-weighted images with a hypointense web- or net-like structure within the hematoma cavity. The reason why some hematomas evolve towards a complex and organized architecture remains unclear; the most common aspect to come to light was the “long standing” of the CSDHs which, in our series, had an average interval of 10 weeks between head injury and initial scan. Recurrence was found to have occurred in 2 patients (6% of cases) in the form of acute subdural hematoma. One patient died as the result of an intraventricular and subarachnoid haemorrhage, while 2 patients (6%) suffered an haemorrhagic stroke ipsilateral to the OCSH. Eighty-nine percent of cases had a good recovery, while 11% remained unchanged or worsened. In select cases, based on the MRI appearance, primary enlarged craniotomy seems to be the treatment of choice for achieving a complete recovery and a reduced recurrence rate in OCSH. PMID:24305027

Training anesthesiology residents in providing anesthesia for awake craniotomy: learning curves and estimate of needed case load.

PubMed

Bilotta, Federico; Titi, Luca; Lanni, Fabiana; Stazi, Elisabetta; Rosa, Giovanni

2013-08-01

To measure the learning curves of residents in anesthesiology in providing anesthesia for awake craniotomy, and to estimate the case load needed to achieve a "good-excellent" level of competence. Prospective study. Operating room of a university hospital. 7 volunteer residents in anesthesiology. Residents underwent a dedicated training program of clinical characteristics of anesthesia for awake craniotomy. The program was divided into three tasks: local anesthesia, sedation-analgesia, and intraoperative hemodynamic management. The learning curve for each resident for each task was recorded over 10 procedures. Quantitative assessment of the individual's ability was based on the resident's self-assessment score and the attending anesthesiologist's judgment, and rated by modified 12 mm Likert scale, reported ability score visual analog scale (VAS). This ability VAS score ranged from 1 to 12 (ie, very poor, mild, moderate, sufficient, good, excellent). The number of requests for advice also was recorded (ie, resident requests for practical help and theoretical notions to accomplish the procedures). Each task had a specific learning rate; the number of procedures necessary to achieve "good-excellent" ability with confidence, as determined by the recorded results, were 10 procedures for local anesthesia, 15 to 25 procedures for sedation-analgesia, and 20 to 30 procedures for intraoperative hemodynamic management. Awake craniotomy is an approach used increasingly in neuroanesthesia. A dedicated training program based on learning specific tasks and building confidence with essential features provides "good-excellent" ability. © 2013 Elsevier Inc. All rights reserved.

Specificities of Awake Craniotomy and Brain Mapping in Children for Resection of Supratentorial Tumors in the Language Area.

PubMed

Delion, Matthieu; Terminassian, Aram; Lehousse, Thierry; Aubin, Ghislaine; Malka, Jean; N'Guyen, Sylvie; Mercier, Philippe; Menei, Philippe

2015-12-01

In the pediatric population, awake craniotomy began to be used for the resection of brain tumor located close to eloquent areas. Some specificities must be taken into account to adapt this method to children. The aim of this clinical study is to not only confirm the feasibility of awake craniotomy and language brain mapping in the pediatric population but also identify the specificities and necessary adaptations of the procedure. Six children aged 11 to 16 were operated on while awake under local anesthesia with language brain mapping for supratentorial brain lesions (tumor and cavernoma). The preoperative planning comprised functional magnetic resonance imaging (MRI) and neuropsychologic and psychologic assessment. The specific preoperative preparation is clearly explained including hypnosis conditioning and psychiatric evaluation. The success of the procedure was based on the ability to perform the language brain mapping and the tumor removal without putting the patient to sleep. We investigated the pediatric specificities, psychological experience, and neuropsychologic follow-up. The children experienced little anxiety, probably in large part due to the use of hypnosis. We succeeded in doing the cortical-subcortical mapping and removing the tumor without putting the patient to sleep in all cases. The psychological experience was good, and the neuropsychologic follow-up showed a favorable evolution. Preoperative preparation and hypnosis in children seemed important for performing awake craniotomy and contributing language brain mapping with the best possible psychological experience. The pediatrics specificities are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

Diagnostic work up for language testing in patients undergoing awake craniotomy for brain lesions in language areas.

PubMed

Bilotta, Federico; Stazi, Elisabetta; Titi, Luca; Lalli, Diana; Delfini, Roberto; Santoro, Antonio; Rosa, Giovanni

2014-06-01

Awake craniotomy is the technique of choice in patients with brain tumours adjacent to primary and accessory language areas (Broca's and Wernicke's areas). Language testing should be aimed to detect preoperative deficits, to promptly identify the occurrence of new intraoperative impairments and to establish the course of postoperative language status. Aim of this case series is to describe our experience with a dedicated language testing work up to evaluate patients with or at risk for language disturbances undergoing awake craniotomy for brain tumour resection. Pre- and intra operative testing was accomplished with 8 tests. Intraoperative evaluation was accomplished when patients were fully cooperative (Ramsey < 3). Postoperative evaluation was scheduled at early (within 21 days) and long-term follow-up (3-6 months). Twenty consecutive patients were prospectively recruited. Preoperative language testings were normal in 9 patients (45%), showed mild to moderate language deficit in 8 (40%) and severe language deficit or aphasic disorders in 3 (15%). Broca's area was identified in 15 patients, in all cases by counting arrest during stimulation and in 12 cases by naming arrest. In this article we describe our experience using a language testing work up to evaluate - pre, intra and postoperatively - patients undergoing awake craniotomy for brain tumour resection with preoperative language disturbances or at risk for postoperative language deficits. This approach allows a systematic evaluation and recording of language function status and can be accomplished even when a neuropsychologist or speech therapist are not involved in the operation crew.

Awake right hemisphere brain surgery.

PubMed

Hulou, M Maher; Cote, David J; Olubiyi, Olutayo I; Smith, Timothy R; Chiocca, E Antonio; Johnson, Mark D

2015-12-01

We report the indications and outcomes of awake right hemispheric brain surgery, as well as a rare patient with crossed aphasia. Awake craniotomies are often performed to protect eloquent cortex. We reviewed the medical records for 35 of 96 patients, in detail, who had awake right hemisphere brain operations. Intraoperative cortical mapping of motor and/or language function was performed in 29 of the 35 patients. A preoperative speech impairment and left hand dominance were the main indicators for awake right-sided craniotomies in patients with right hemisphere lesions. Four patients with lesion proximity to eloquent areas underwent awake craniotomies without cortical mapping. In addition, one patient had a broncho-pulmonary fistula, and another had a recent major cardiac procedure that precluded awake surgery. An eloquent cortex representation was identified in 14 patients (48.3%). Postoperatively, seven of 17 patients (41.1%) who presented with weakness, experienced improvements in their motor functions, 11 of 16 (68.7%) with seizures became seizure-free, and seven of nine (77.7%) with moderate to severe headaches and one of two with a visual field deficit improved significantly. There were also improvements in speech and language functions in all patients who presented with speech difficulties. A right sided awake craniotomy is an excellent option for left handed patients, or those with right sided cortical lesions that result in preoperative speech impairments. When combined with intraoperative cortical mapping, both speech and motor function can be well preserved. Copyright © 2015 Elsevier Ltd. All rights reserved.

Surgical quality of wedge resection affects overall survival in patients with early stage non-small cell lung cancer.

PubMed

Ajmani, Gaurav S; Wang, Chi-Hsiung; Kim, Ki Wan; Howington, John A; Krantz, Seth B

2018-07-01

Very few studies have examined the quality of wedge resection in patients with non-small cell lung cancer. Using the National Cancer Database, we evaluated whether the quality of wedge resection affects overall survival in patients with early disease and how these outcomes compare with those of patients who receive stereotactic radiation. We identified 14,328 patients with cT1 to T2, N0, M0 disease treated with wedge resection (n = 10,032) or stereotactic radiation (n = 4296) from 2005 to 2013 and developed a subsample of propensity-matched wedge and radiation patients. Wedge quality was grouped as high (negative margins, >5 nodes), average (negative margins, ≤5 nodes), and poor (positive margins). Overall survival was compared between patients who received wedge resection of different quality and those who received radiation, adjusting for demographic and clinical variables. Among patients who underwent wedge resection, 94.6% had negative margins, 44.3% had 0 nodes examined, 17.1% had >5 examined, and 3.0% were nodally upstaged; 16.7% received a high-quality wedge, which was associated with a lower risk of death compared with average-quality resection (adjusted hazard ratio [aHR], 0.74; 95% confidence interval [CI], 0.67-0.82). Compared with stereotactic radiation, wedge patients with negative margins had significantly reduced hazard of death (>5 nodes: aHR, 0.50; 95% CI, 0.43-0.58; ≤5 nodes: aHR, 0.65; 95% CI, 0.60-0.70). There was no significant survival difference between margin-positive wedge and radiation. Lymph nodes examined and margins obtained are important quality metrics in wedge resection. A high-quality wedge appears to confer a significant survival advantage over lower-quality wedge and stereotactic radiation. A margin-positive wedge appears to offer no benefit compared with radiation. Copyright © 2018 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Vertebral body or intervertebral disc wedging: which contributes more to thoracolumbar kyphosis in ankylosing spondylitis patients?: A retrospective study.

PubMed

Liu, Hao; Qian, Bang-Ping; Qiu, Yong; Wang, Yan; Wang, Bin; Yu, Yang; Zhu, Ze-Zhang

2016-09-01

Both vertebral body wedging and disc wedging are found in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis. However, their relative contribution to thoracolumbar kyphosis is not fully understood. The objective of this study was to compare different contributions of vertebral and disc wedging to the thoracolumbar kyphosis in AS patients, and to analyze the relationship between the apical vertebral wedging angle and thoracolumbar kyphosis.From October 2009 to October 2013, a total of 59 consecutive AS patients with thoracolumbar kyphosis with a mean age of 38.1 years were recruited in this study. Based on global kyphosis (GK), 26 patients with GK < 70° were assigned to group A, and the other 33 patients with GK ≥ 70° were included in group B. Each GK was divided into disc wedge angles and vertebral wedge angles. The wedging angle of each disc and vertebra comprising the thoracolumbar kyphosis was measured, and the proportion of the wedging angle to the GK was calculated accordingly. Intergroup and intragroup comparisons were subsequently performed to investigate the different contributions of disc and vertebra to the GK. The correlation between the apical vertebral wedging angle and GK was calculated by Pearson correlation analysis. The duration of disease and sex were also recorded in this study.With respect to the mean disease duration, significant difference was observed between the two groups (P < 0.01). The wedging angle and wedging percentage of discs were significantly higher than those of vertebrae in group A (34.8° ± 2.5° vs 26.7° ± 2.7°, P < 0.01 and 56.6% vs 43.4%, P < 0.01), whereas disc wedging and disc wedging percentage were significantly lower than vertebrae in group B (37.6° ± 7.0° vs 50.1° ± 5.1°, P < 0.01 and 42.7% vs 57.3%, P < 0.01). The wedging of vertebrae was significantly higher in group B than in group A (50.1° ± 5.1° vs 26.7° ± 2.7°, P < 0.01). Additionally, correlation analysis revealed a significant correlation between the apical vertebral wedging angle and GK (R = 0.850, P = 0.001).Various disc and vertebral wedging exist in thoracolumbar kyphosis secondary to AS. The discs wedging contributes more to the thoracolumbar kyphosis in patients with GK < 70° than vertebral wedging, whereas vertebral wedging is more conducive to the thoracolumbar kyphosis in patients with GK ≥ 70°, indicating different biomechanical pathogenesis in varied severity of thoracolumbar kyphosis secondary to AS.

Vertebral body or intervertebral disc wedging: which contributes more to thoracolumbar kyphosis in ankylosing spondylitis patients?

PubMed Central

Liu, Hao; Qian, Bang-Ping; Qiu, Yong; Wang, Yan; Wang, Bin; Yu, Yang; Zhu, Ze-Zhang

2016-01-01

Abstract Both vertebral body wedging and disc wedging are found in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis. However, their relative contribution to thoracolumbar kyphosis is not fully understood. The objective of this study was to compare different contributions of vertebral and disc wedging to the thoracolumbar kyphosis in AS patients, and to analyze the relationship between the apical vertebral wedging angle and thoracolumbar kyphosis. From October 2009 to October 2013, a total of 59 consecutive AS patients with thoracolumbar kyphosis with a mean age of 38.1 years were recruited in this study. Based on global kyphosis (GK), 26 patients with GK < 70° were assigned to group A, and the other 33 patients with GK ≥ 70° were included in group B. Each GK was divided into disc wedge angles and vertebral wedge angles. The wedging angle of each disc and vertebra comprising the thoracolumbar kyphosis was measured, and the proportion of the wedging angle to the GK was calculated accordingly. Intergroup and intragroup comparisons were subsequently performed to investigate the different contributions of disc and vertebra to the GK. The correlation between the apical vertebral wedging angle and GK was calculated by Pearson correlation analysis. The duration of disease and sex were also recorded in this study. With respect to the mean disease duration, significant difference was observed between the two groups (P < 0.01). The wedging angle and wedging percentage of discs were significantly higher than those of vertebrae in group A (34.8° ± 2.5° vs 26.7° ± 2.7°, P < 0.01 and 56.6% vs 43.4%, P < 0.01), whereas disc wedging and disc wedging percentage were significantly lower than vertebrae in group B (37.6° ± 7.0° vs 50.1° ± 5.1°, P < 0.01 and 42.7% vs 57.3%, P < 0.01). The wedging of vertebrae was significantly higher in group B than in group A (50.1° ± 5.1° vs 26.7° ± 2.7°, P < 0.01). Additionally, correlation analysis revealed a significant correlation between the apical vertebral wedging angle and GK (R = 0.850, P = 0.001). Various disc and vertebral wedging exist in thoracolumbar kyphosis secondary to AS. The discs wedging contributes more to the thoracolumbar kyphosis in patients with GK < 70° than vertebral wedging, whereas vertebral wedging is more conducive to the thoracolumbar kyphosis in patients with GK ≥ 70°, indicating different biomechanical pathogenesis in varied severity of thoracolumbar kyphosis secondary to AS. PMID:27661026

Episodic Growth of Fold-Thrust Belts: Insights from Finite Element Modelling

NASA Astrophysics Data System (ADS)

Yang, X.; Peel, F.; Sanderson, D. J.; McNeill, L. C.

2016-12-01

The sequential development of an imbricate thrust system was investigated using a set of 2D FEM models. This study provides new insights on how the style and location of thrust activity changes through cycles of thrust accretion by making refined measurements of the thrust system parameters through time and tracking these parameters through each cycle. In addition to conventional wedge parameters (i.e. surface slope, wedge width and height), the overall taper angle is used to determine how the critical taper angle is reached; a particular focus is on the region of outboard minor horizontal displacement provides insights into the forward propagation of material within, and in front of, the thrust wedge; tracking the position of the failure front (where the frontal thrust roots into the basal detachment) reveals the sequence and advancement of the imbricate thrusts. The model results show that a thrust system is generally composed of three deformation components: thrust wedge, pre-wedge and wedge front. A thrust belt involves growth that repeats episodically and cyclically. When a wedge reaches critical taper ( 10°), thrust movement within the wedge slows while the taper angle and wedge width gradually increase. In contrast, the displacement front (tracked here by the location of 0 m displacement) rapidly propagates forward along whilst the wedge height is fast growing. During this period, the wedge experiences a significant shortening after a new thrust initiates at the failure front, leading to an obvious decrease in wedge width. As soon as the critical taper is achieved, wedge interior (tracked here by the location of 50 m displacement) accelerates forward reducing the taper angle below critical. This is accompanied by a sudden increase in wedge width, slow advancement of displacement front, and slow uplift of the fold-thrust belt. The rapid movements within and in front of the wedge occur alternately. The model results also show that there is clear, although minor, activity (5-10 m displacement) in front of the thrust wedge, which distinguishes the failure front from the displacement front throughout the fold-thrust belt development. This spatial and temporal relationship may not have been previously recognized in natural systems.

Dosimetric Characteristics of Wedged Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sidhu, N.P.S.; Breitman, Karen

2015-01-15

The beam characteristics of the wedged fields in the nonwedged planes (planes normal to the wedged planes) were studied for 6 MV and 15 MV x-ray beams. A method was proposed for determining the maximum field length of a wedged field that can be used in the nonwedged plane without introducing undesirable alterations in the dose distributions of these fields. The method requires very few measurements. The relative wedge factors of 6 MV and 15 MV X-rays were determined for wedge filters of nominal wedge angles of 15°, 30°, 45°, and 60° as a function of depth and field size.more » For a 6 MV beam the relative wedge factors determined for a field size of 10 × 10 cm{sup 2} for 30°, 45°, and 60° wedge filters can be used for various field sizes ranging from 4 cm{sup 2} to 20 cm{sup 2} (except for the 60° wedge for which the maximum field size that can be used is 15 × 20 cm{sup 2}) without introducing errors in the dosimetric calculations of more than 0.5% for depths up to 20 cm and 1% for depths up to 30 cm. For the 15° wedge filter the relative wedge factor for a field size of 10 × 10 cm{sup 2} can be used over the same range of field sizes by introducing slightly higher error, 0.5% for depths up to 10 cm and 1% for depths up to 30 cm. For a 15 MV beam the maximum magnitude of the relative wedge factors for 45° and 60° lead wedges is of the order of 1%, and it is not important clinically to apply a correction of that magnitude. For a 15 MV beam the relative wedge factors determined for a field size of 6 × 6 cm{sup 2} for the 15° and 30° steel wedges can be used over a range of field sizes from 4 cm{sup 2} to 20 cm{sup 2} without causing dosimetric errors greater than 0.5% for depths up to 10 cm.« less

The influence of wedge diffuser blade number and divergence angle on the performance of a high pressure ratio centrifugal compressor

NASA Astrophysics Data System (ADS)

Wang, Yi; Han, Ge; Lu, Xingen; Zhu, Junqiang

2018-02-01

Wedge diffuser is widely used in centrifugal compressors due to its high performance and compact size. This paper is aimed to research the influence of wedge diffuser blade number and divergence angle on centrifugal compressor performance. The impact of wedge diffuser blade number on compressor stage performance is investigated, and then the wedge diffusers with different divergence angle are studied by varying diffuser wedge angle and blade number simultaneously. It is found that wedge diffuser with 27 blades could have about 0.8% higher adiabatic efficiency and 0.14 higher total pressure ratio than the wedge diffuser with 19 blades and the best compressor performance is achieved when diffuser divergence angle is 8.3°.These results could give some advices on centrifugal compressor design.

[Effect of epidural drainage and dural tenting suture on epidural hematoma in 145 cases of craniotomy].

PubMed

Zhao, Jie; Liu, Zhixiong; Liu, Yunsheng; Liu, Jinfang; Fang, Wenhua; Rao, Yihua; Yang, Liang; Yuan, Xianrui

2010-03-01

To evaluate the efficacy of dural tenting suture and epidural drainage in craniotomy. In 145 cases of intracranial lesions, dural tenting suture and epidural drainage were performed to prevent epidural hematoma. Postoperative computed tomography (CT) showed no epidural hematoma required surgery in both groups. Both dural tenting suture and epidural drainage are effective in preventing epidural hematoma. Hemostasis is the key step. Dural tenting suture without epidural drainage relieves psychological stress. It decreases the risk of intracranial infection and avoids some unusual complications.

The Critical Size Defect as an Experimental Model for Craniomaxillofacial Nonunions,

DTIC Science & Technology

1985-01-01

union evident at two months. The wider defects of 12 m, 15 m, and 18 mm in length exhibited bony union in four months but exhibited drainage either...Prolo, D.J., (-btierrez, R.V., DeVine, J.S., and (*und, R.A.: Clinical l1tility of Alloqeneic Skull Discs in Human Craniotomy . Neurosurgery. 14:1R3, 1984...1. R rm craniotomy defect prepared in dried rat skull. Piq. 2. 15 rm craniotamy defect in dried rabbit skull. Fig. 3. r-ied dog mandible qhowing

Total knee arthroplasty after failed high tibial osteotomy: a systematic review of open versus closed wedge osteotomy.

PubMed

Han, Jae Hwi; Yang, Jae-Hyuk; Bhandare, Nikhl N; Suh, Dong Won; Lee, Jong Seong; Chang, Yong Suk; Yeom, Ji Woong; Nha, Kyung Wook

2016-08-01

Medial opening wedge high tibial osteotomy (HTO) has become increasingly popular as an alternative to lateral closing wedge osteotomy for the treatment of medial compartment knee osteoarthritis with varus deformity. The present systematic review was conducted to provide an objective analysis of total knee arthroplasty (TKA) outcomes following previous knee osteotomy (medial opening wedge vs. lateral closing wedge). A literature search of online databases (MEDLINE, EMBASE, Cochrane Library database) was made, in addition to manual search of major orthopaedic journals. The methodological quality of each of the studies was assessed on the Newcastle-Ottawa Scale and Effective Practice and Organization of Care. A total of ten studies were included in the review. There were eight studies with Level IV and two studies with Level III evidence. Eight studies reported clinical and radiologic scores. Comparative studies between TKA following medial opening and lateral closing wedge HTO did not demonstrate statistically significant clinical and radiologic differences. The revision rates were similar. However, more technical issues during TKA surgery after lateral closing wedge HTO were mentioned than the medial open wedge group. The quadriceps snip, tibial tubercle osteotomy, and lateral soft tissue release were more frequently needed in the lateral closing wedge HTO group. In addition, because of loss of proximal tibia bone geometry in the lateral closing wedge HTO group, concerns such as tibia stem impingement in the lateral tibial cortex was noted. The present systematic review suggests that TKA after medial opening and lateral closing wedge HTO showed similar performance. Clinical and radiologic outcome including revision rates did not statistically differ from included studies. However, there are more surgical technical concerns in TKA conversion from lateral closing wedge HTO than from the medial opening wedge HTO group. IV.

Study on the shock interference in a wedged convergent-divergent channel

NASA Astrophysics Data System (ADS)

Yu, F. M.; Wang, C. Z.

The investigation of shock reflection-to-diffraction phenomena upon a wedged convergent-divergent channel produced by a planar incident shock wave have been done in the shock tube facility of Institute of Aeronautics and Astronautics, National Cheng-Kung University. The experiment proceeds upon seven wedged convergent-divergent channels with the forward and rear wedge angles arrangement of them are (50°, 50°), (35°, 35°), (50°, 35°), (35°, 50°), (50°, 0°), (35°, 0°), and (90°, 0°), respectively. They were tested at Mach numbers of 1.1, 1.2, 1.3, 1.4, 1.5 and 1.6, respectively. On the first wedged channel, following the regular reflection on a 50°- wedged surface by the incident shock wave, shock diffraction with Mach stem has been observed as it moves to the downstream wedge surface. On the apex of the wedge, the secondary reflected shock behaviors as a sector of the blast shock moving toward the centerline of the channel. From the color schlieren pictures it has been observed that there exists a pattern of blast-wave-type high gas density gradient region near the wedge apex. Following the Mach reflection from the 35° -wedged surface on which only the Mach stem diffracted across the apex and following with a small region of disturbed acoustic wave front. The shock interference, which proceeds by the Mach reflection-to-diffraction generates a very complicate vortical flow structure. The measurement of the peak pressure along centerline of the channel downstream of the wedge apex indicates that it is larger near the apex and it decreases downstream. It is larger for larger convergent wedge angle and It is smaller for larger divergent wedge angle.

A regional-scale estimation of ice wedge ice volumes in the Canadian High Arctic

NASA Astrophysics Data System (ADS)

Templeton, M.; Pollard, W. H.; Grand'Maison, C. B.

2016-12-01

Ice wedges are both prominent and environmentally vulnerable features in continuous permafrost environments. As the world's Arctic regions begin to warm, concern over the potential effects of ice wedge melt out has become an immediate issue, receiving much attention in the permafrost literature. In this study we estimate the volume of ice wedge ice for large areas in the Canadian High Arctic through the use of high resolution satellite imagery and the improved capabilities of Geographic Information Systems (GIS). The methodology used for this study is similar to that of one performed in Siberia and Alaska by Ulrich et al, in 2014. Utilizing Ulrich's technique, this study detected ice wedge polygons from satellite imagery using ArcGIS. The average width and depth of these ice wedges were obtained from a combination of field data and long-term field studies for the same location. The assumptions used in the analysis of ice wedge volume have been tested, including trough width being representative of ice wedge width, and ice wedge ice content (Pollard and French 1980). This study used specific field sites located near Eureka on Ellesmere Island (N80°01', W85°43') and at Expedition Fiord on Axel Heiberg Island (N79°23', W90°59'). The preliminary results indicate that the methodology used by Ulrich et al, 2014 is transferrable to the Canadian High Arctic, and that ice wedge volumes range between 3-10% of the upper part of permafrost. These findings are similar to previous studies and their importance is made all the more evident by the dynamic nature of ice wedges where it could be argued that they are a key driver of thermokarst terrain. The ubiquitous nature of ice wedges across arctic terrain highlights the importance and the need to improve our understanding of ice wedge dynamics, as subsidence from ice wedge melt-out could lead to large scale landscape change.

Estimation of internal friction angle of subduction zone in northeast of Japan by using seismic focal mechanisms

NASA Astrophysics Data System (ADS)

Miyakawa, A.; Sato, K.; Otsubo, M.

2017-12-01

Physical properties, such as friction angle of the material, is important to understand the interplate earthquake of a subduction zone. Coulomb wedge model (Davis et al., 1983, JGR) is successfully revealed the relationship between a geometry of an accretionary wedge in a subduction zone and the physical properties of the material composing the accretionary wedge (e.g. Dahlen, 1984, JGR). An internal friction angle of the wedge and the frictional strength of the plate boundary fault control the wedge angle according to the Coulomb wedge model. However, the internal friction angle of the wedge and the frictional strength of the plate boundary fault are hard to estimate. Many previous works assumed the internal friction angle of the wedge on the basis of the laboratory experiments. Then, the frictional strength of the plate boundary fault, which is usually most interested, were evaluated from the observed wedge angle and the assumed internal friction angle of the wedge. Consequently, we should be careful of the selection of the internal friction angle of the wedge, otherwise, the uncertain an inappropriate internal friction angle may mislead the frictional strength of the plate boundary fault. In this study, we employed the newly developed technique to evaluate the internal friction angle of the wedge from the earthquake focal mechanisms occurred in the wedge along Japan Trench, northeast Japan. We used 650 earthquake mechanisms determined by NIED, Japan for the stress and friction coefficient inversion. The stress and friction coefficient inversion method is modified to handle the earthquake focal mechanisms from a computerized method to estimate the friction coefficient from the orientation distribution of faults (Sato, 2016, JSG). Finally, we obtained 25 degrees of internal friction angle of the wedge from the inversion. This value of friction angle is lower than usually assumed internal friction angle (30 degrees) (Byerlee, 1978, PAGEOPH). This lower internal friction angle leads to lower frictional strength of plate boundary fault ( 0.35) according to the Coulomb wedge model. These constrained physical parameters can contribute to understanding the interplate earthquake at each subduction zones.

Tumor location and IDH1 mutation may predict intraoperative seizures during awake craniotomy.

PubMed

Gonen, Tal; Grossman, Rachel; Sitt, Razi; Nossek, Erez; Yanaki, Raneen; Cagnano, Emanuela; Korn, Akiva; Hayat, Daniel; Ram, Zvi

2014-11-01

Intraoperative seizures during awake craniotomy may interfere with patients' ability to cooperate throughout the procedure, and it may affect their outcome. The authors have assessed the occurrence of intraoperative seizures during awake craniotomy in regard to tumor location and the isocitrate dehydrogenase 1 (IDH1) status of the tumor. Data were collected in 137 consecutive patients who underwent awake craniotomy for removal of a brain tumor. The authors performed a retrospective analysis of the incidence of seizures based on the tumor location and its IDH1 mutation status, and then compared the groups for clinical variables and surgical outcome parameters. Tumor location was strongly associated with the occurrence of intraoperative seizures. Eleven patients (73%) with tumor located in the supplementary motor area (SMA) experienced intraoperative seizures, compared with 17 (13.9%) with tumors in the other three non-SMA brain regions (p < 0.0001). Interestingly, there was no significant association between history of seizures and tumor location (p = 0.44). Most of the patients (63.6%) with tumor in the SMA region harbored an IDH1 mutation compared with those who had tumors in non-SMA regions. Thirty-one of 52 patients (60%) with a preoperative history of seizures had an IDH1 mutation (p = 0.02), and 15 of 22 patients (68.2%) who experienced intraoperative seizures had an IDH1 mutation (p = 0.03). In a multivariate analysis, tumor location was found as a significant predictor of intraoperative seizures (p = 0.002), and a trend toward IDH1 mutation as such a predictor was found as well (p = 0.06). Intraoperative seizures were not associated with worse outcome. Patients with tumors located in the SMA are more prone to develop intraoperative seizures during awake craniotomy compared with patients who have a tumor in non-SMA frontal areas and other brain regions. The IDH1 mutation was more common in SMA region tumors compared with other brain regions, and may be an additional risk factor for the occurrence of intraoperative seizures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Handford, C.R.

Exploration is increasingly dependent upon obtaining credible stratigraphic interpretations of seismic data. With respect to carbonate platforms, two of the most important seismic-imaging and interpretation problems are (1) distinguishing between lowstand unconformities and drowning unconformities, and (2) recognizing paleokarst reservoirs. Lowstand unconformities vs. drowning unconformities. Many contend that onlapping wedges of strata above sequence boundaries but below the previous shelf break comprise the lowstand systems tract. An alternative view is that onlapping wedges do not record sea level falls, but instead chronicle sea level rises and platform demise. A Mississippian carbonate ramp exposed along the southern margin of North Americamore » is flanked by a siliciclastic lowstand wedge and overlain by a drowning succession of black shales. This dual history of lowstand exposure and drowning formed two baselap surfaces, which lie so close to each other on the shelf that seismic dissemination is almost impossible. The paradox is that although the ramp was terminated by drowning, the visible seismic baselap was due to low-stand exposure. Numerous large fields around the world produce from carbonate reservoirs with a moderate to strong paleokarst overprint. Their discoveries, however, were structurally driven and rarely based upon predrill knowledge of paleokarst systems. In fact, there has been little effort to determine how to recognize paleocave systems in seismic reflection data. To narrow this gap, the sedimentary fill and stratal geometries of modern cave systems were examined and modeled seismically. The models show a passage from continuous reflections in the undisturbed country rock to discontinuous reflections inclined toward the cavern core. Velocity pull-ups and pull-downs are significant where velocity and density contrasts between the country rock and collapsed chamber are important.« less

Experimental investigation of sound absorption of acoustic wedges for anechoic chambers

NASA Astrophysics Data System (ADS)

Belyaev, I. V.; Golubev, A. Yu.; Zverev, A. Ya.; Makashov, S. Yu.; Palchikovskiy, V. V.; Sobolev, A. F.; Chernykh, V. V.

2015-09-01

The results of measuring the sound absorption by acoustic wedges, which were performed in AC-3 and AC-11 reverberation chambers at the Central Aerohydrodynamic Institute (TsAGI), are presented. Wedges of different densities manufactured from superfine basaltic and thin mineral fibers were investigated. The results of tests of these wedges were compared to the sound absorption of wedges of the operating AC-2 anechoic facility at TsAGI. It is shown that basaltic-fiber wedges have better sound-absorption characteristics than the investigated analogs and can be recommended for facing anechoic facilities under construction.

Evaluating the dose to the contralateral breast when using a dynamic wedge versus a regular wedge.

PubMed

Weides, C D; Mok, E C; Chang, W C; Findley, D O; Shostak, C A

1995-01-01

The incidence of secondary cancers in the contralateral breast after primary breast irradiation is several times higher than the incidence of first time breast cancer. Studies have shown that the scatter radiation to the contralateral breast may play a large part in the induction of secondary breast cancers. Factors that may contribute to the contralateral breast dose may include the use of blocks, the orientation of the field, and wedges. Reports have shown that the use of regular wedges, particularly for the medial tangential field, gives a significantly higher dose to the contralateral breast compared to an open field. This paper compares the peripheral dose outside the field using a regular wedge, a dynamic wedge, and an open field technique. The data collected consisted of measurements taken with patients, solid water and a Rando phantom using a Varian 2300CD linear accelerator. Ion chambers, thermoluminescent dosimeters (TLD), diodes, and films were the primary means for collecting the data. The measurements show that the peripheral dose outside the field using a dynamic wedge is close to that of open fields, and significantly lower than that of regular wedges. This information indicates that when using a medial wedge, a dynamic wedge should be used.

Necessity of Surgical Site Closed Suction Drain for Pterional Craniotomy

PubMed Central

Choi, Su Yong; Yoon, Sung Min; Yoo, Chan Jong; Kim, Young Bo; Kim, Woo Kyung

2015-01-01

Objective The aim of this study was to assess the benefit of using a prophylactic surgical site closed suction drain in pterional craniotomy. Materials and Methods A retrospective review was conducted on 607 consecutive patients who underwent a pterional craniotomy for treatment of intracranial anterior circulation aneurysms over a 5-year period. Between January 2000 and December 2004, 607 patients were divided into two groups, those who had a prophylactic suction drain during closure of the surgical site (drain group, DG) and those who did not (non-drain group, NDG). Head computed tomography (CT) was taken routinely on postoperative day (POD) 1, 7, and 14. Patients' demographics, incidence of surgical site complications, and courses of surgical site healing which were evaluated radiologically by the thickness of the surgical site myocutaneous layer, were analyzed between DG and NDG. Results Patients' demographics and characteristics did not differ significantly between the two groups. The head CT showed that the degree of changes in the postoperative surgical site thickness was 148% at POD 1, 209% at POD 7, and 198% at POD 14 in DG, and 118% at POD 1, 152% at POD 7, and 158% at POD 14 in NDG compared to the preoperative value. Postoperative surgical site hematoma was 7.9% (22/274) in DG and 2.4% (8/333) in NDG. Conclusion Prophylactic use of an epidural and/or subgaleal closed suction drain does not appear to be necessary for prevention of postoperative surgical site hematoma as well as for promotion of surgical site healing in pterional craniotomy. PMID:26523255

Acute Monocular Blindness Due to Orbital Compartment Syndrome Following Pterional Craniotomy.

PubMed

Habets, Jeroen G V; Haeren, Roel H L; Lie, Suen A N; Bauer, Noel J C; Dings, Jim T A

2018-06-01

We present a case of orbital compartment syndrome (OCS) leading to monocular irreversible blindness following a pterional craniotomy for clipping of an anterior communicating artery aneurysm. OCS is an uncommon but vision-threatening entity requiring urgent decompression to reduce the risk of permanent visual loss. Iatrogenic orbital roof defects are a common finding following pterional craniotomies. However, complications related to these defects are rarely reported. A 65-year-old female who underwent an anterior communicating artery clipping via a pterional approach 4 days before developed proptosis, ocular movement paresis, and irreversible visual impairment following an orthopedic surgery. Computed tomography images revealed an intraorbital cerebrospinal fluid (CSF) collection, which was evacuated via an acute recraniotomy. The next day, proptosis and intraorbital CSF collection on computed tomography images reoccurred and an oral and maxillofacial surgeon evacuated the collection via a blepharoplasty incision and blunt dissection. In addition, the patient was treated with acetazolamide and an external lumbar CSF drainage during 12 days. Hereafter, the CSF collection did not reoccur. Unfortunately, monocular blindness was persistent. We hypothesize the CSF collection occurred due to the combination of a postoperative orbital roof defect and a temporarily increased intracranial pressure during the orthopedic surgery. We plead for more awareness of this severe complication after pterional surgeries and emphasize the importance of 1) strict ophthalmologic examination after pterional craniotomies in case of intracranial pressure increasing events, 2) immediate consultation of an oral and maxillofacial surgeon, and 3) consideration of CSF-draining interventions since symptoms are severely invalidating and irreversible within a couple of hours. Copyright © 2018 Elsevier Inc. All rights reserved.

Awake craniotomy may further improve neurological outcome of intraoperative MRI-guided brain tumor surgery.

PubMed

Tuominen, Juho; Yrjänä, Sanna; Ukkonen, Anssi; Koivukangas, John

2013-10-01

Results of awake craniotomy are compared to results of resections done under general anesthesia in patients operated with IMRI control. We hypothesized that stimulation of the cortex and white matter during awake surgery supplements IMRI control allowing for safer resection of eloquent brain area tumors. The study group consisted of 20 consecutive patients undergoing awake craniotomy with IMRI control. Resection outcome of these patients was compared to a control group of 20 patients operated in the same IMRI suite but under general anesthesia without cortical stimulation. The control group was composed of those patients whose age, sex, tumor location, recurrence and histology best matched to patients in study group. Cortical stimulation identified functional cortex in eight patients (40 %). Postoperatively the neurological condition in 16 patients (80 %) in the study group was unchanged or improved compared with 13 patients (65 %) in the control group. In both groups, three patients (15 %) had transient impairment symptoms. There was one patient (5 %) with permanent neurological impairment in the study group compared to four patients (20 %) in the control group. These differences between groups were not statistically significant. There was no surgical mortality in either group and the overall infection rate was 5 %. Mean operation time was 4 h 45 min in the study group and 3 h 15 min in the control group. The study consisted of a limited patient series, but it implies that awake craniotomy with bipolar cortical stimulation may help to reduce the risk of postoperative impairment following resection of tumors located in or near speech and motor areas also under IMRI control.

The Cost of Brain Surgery: Awake vs Asleep Craniotomy for Perirolandic Region Tumors.

PubMed

Eseonu, Chikezie I; Rincon-Torroella, Jordina; ReFaey, Karim; Quiñones-Hinojosa, Alfredo

2017-08-01

Cost effectiveness has become an important factor in the health care system, requiring surgeons to improve efficacy of procedures while reducing costs. An awake craniotomy (AC) with direct cortical stimulation (DCS) presents one method to resect eloquent region tumors; however, some authors assert that this procedure is an expensive alternative to surgery under general anesthesia (GA) with neuromonitoring. To evaluate the cost effectiveness and clinical outcomes between AC and GA patients. Retrospective analysis of a cohort of 17 patients with perirolandic gliomas who underwent an AC with DCS were case-control matched with 23 patients with perirolandic gliomas who underwent surgery under GA with neuromonitoring (ie, motor-evoked potentials, somatosensory-evoked potentials, phase reversal). Inpatient costs, quality-adjusted life years (QALY), extent of resection, and neurological outcome were compared between the groups. Total inpatient expense per patient was $34 804 in the AC group and $46 798 in the GA group ( P = .046). QALY score for the AC group was 0.97 and 0.47 for the GA group ( P = .041). The incremental cost per QALY for the AC group was $82 720 less than the GA group. Postoperative Karnofsky performance status was 91.8 in the AC group and 81.3 in the GA group (P = .047). Length of hospitalization was 4.12 days in the AC group and 7.61 days in the GA group ( P = .049). The total inpatient costs for awake craniotomies were lower than surgery under GA. This study suggests better cost effectiveness and neurological outcome with awake craniotomies for perirolandic gliomas. Copyright © 2017 by the Congress of Neurological Surgeons

Clinical outcomes from maximum-safe resection of primary and metastatic brain tumors using awake craniotomy.

PubMed

Groshev, Anastasia; Padalia, Devang; Patel, Sephalie; Garcia-Getting, Rosemarie; Sahebjam, Solmaz; Forsyth, Peter A; Vrionis, Frank D; Etame, Arnold B

2017-06-01

To retrospectively analyze outcomes in patients undergoing awake craniotomies for tumor resection at our institution in terms of extent of resection, functional preservation and length of hospital stay. All cases of adults undergoing awake-craniotomy from September 2012-February 2015 were retrospectively reviewed based on an IRB approved protocol. Information regarding patient age, sex, cancer type, procedure type, location, hospital stay, extent of resection, and postoperative complications was extracted. 76 patient charts were analyzed. Resected cancer types included metastasis to the brain (41%), glioblastoma (34%), WHO grade III anaplastic astrocytoma (18%), WHO grade II glioma (4%), WHO grade I glioma (1%), and meningioma (1%). Over a half of procedures were performed in the frontal lobes, followed by temporal, and occipital locations. The most common indication was for motor cortex and primary somatosensory area lesions followed by speech. Extent of resection was gross total for 59% patients, near-gross total for 34%, and subtotal for 7%. Average hospital stay for the cohort was 1.7days with 75% of patients staying at the hospital for only 24h or less post surgery. In the postoperative period, 67% of patients experienced improvement in neurological status, 21% of patients experienced no change, 7% experienced transient neurological deficits, which resolved within two months post op, 1% experienced transient speech deficit, and 3% experienced permanent weakness. In a consecutive series of 76 patients undergoing maximum-safe resection for primary and metastatic brain tumors, awake-craniotomy was associated with a short hospital stay and low postoperative complications rate. Copyright © 2017 Elsevier B.V. All rights reserved.

Efficacy and Safety of a Lidocaine and Ropivacaine Mixture for Scalp Nerve Block and Local Infiltration Anesthesia in Patients Undergoing Awake Craniotomy.

PubMed

Chaki, Tomohiro; Sugino, Shigekazu; Janicki, Piotr K; Ishioka, Yoshiya; Hatakeyama, Yosuke; Hayase, Tomo; Kaneuchi-Yamashita, Miki; Kohri, Naonori; Yamakage, Michiaki

2016-01-01

Mixtures of various local anesthetics, such as lidocaine and ropivacaine, have been widely used. However, their efficacy and safety for scalp nerve blocks and local infiltration during awake craniotomy have not been fully elucidated. We prospectively investigated 53 patients who underwent awake craniotomy. Scalp block was performed for the blockade of the supraorbital, supratrochlear, zygomaticotemporal, auriculotemporal, greater occipital, and lesser occipital nerves with a mixture containing equal volumes of 2% lidocaine and 0.75% ropivacaine, including 5 μg/mL of epinephrine. Infiltration anesthesia was applied at the site of skin incision using the same mixture. The study outcomes included changes in heart rate and blood pressure after head pinning and skin incision, and incidence of severe pain on emergence from anesthesia. Total doses and plasma concentrations of lidocaine and ropivacaine were measured at different time points after performing the block. The heart rate and blood pressure after head pinning were marginally, but significantly, increased when compared with baseline values. There were no significant differences in heart rate and blood pressure before and after the skin incision. Nineteen percent of the patients (10/53) complained of incisional pain at emergence from anesthesia. The highest observed blood concentrations of lidocaine and ropivacaine were 1.9±0.9 and 1.1±0.4 μg/mL, respectively. No acute anesthetic toxicity symptom was observed. Scalp block with a mixture of lidocaine and ropivacaine seems to provide effective and safe anesthetic management in patients undergoing awake craniotomy.

Using a Virtual Reality Social Network During Awake Craniotomy to Map Social Cognition: Prospective Trial.

PubMed

Bernard, Florian; Lemée, Jean-Michel; Aubin, Ghislaine; Ter Minassian, Aram; Menei, Philippe

2018-06-26

In awake craniotomy, it is possible to temporarily inactivate regions of the brain using direct electrical stimulation, while the patient performs neuropsychological tasks. If the patient shows decreased performance in a given task, the neurosurgeon will not remove these regions, so as to maintain all brain functions. The objective of our study was to describe our experience of using a virtual reality (VR) social network during awake craniotomy and discuss its future applications for perioperative mapping of nonverbal language, empathy, and theory of mind. This was a single-center, prospective, unblinded trial. During wound closure, different VR experiences with a VR headset were proposed to the patient. This project sought to explore interactions with the neuropsychologist's avatar in virtual locations using a VR social network as an available experience. Three patients experienced VR. Despite some limitations due to patient positioning during the operation and the limitation of nonverbal cues inherent to the app, the neuropsychologist, as an avatar, could communicate with the patient and explore gesture communication while wearing a VR headset. With some improvements, VR social networks can be used in the near future to map social cognition during awake craniotomy. ClinicalTrials.gov NCT03010943; https://clinicaltrials.gov/ct2/show/NCT03010943 (Archived at WebCite at http://www.webcitation.org/70CYDil0P). ©Florian Bernard, Jean-Michel Lemée, Ghislaine Aubin, Aram Ter Minassian, Philippe Menei. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 26.06.2018.

[How much pressure is applied on the eye balls during craniotomy?: Measurement with FlexiForce contact surface force sensor].

PubMed

Okada, Takeshi; Ishikawa, Tatsuya; Nishimura, Hiromi; Suzuki, Akifumi

2012-12-01

Visual loss following craniotomy is a serious postoperative complication in which elevation of ocular pressure during retraction of the skin flap may cause retinal ischemia. We reported that continuous monitoring of extraocular pressure with the FlexiForce sensor may avoid excessive skin flap retraction during craniotomy and thus prevent ocular complications. Between January 2008 and December 2011, we analyzed data from 46 consecutive patients for whom continuous monitoring of extraocular pressure with FlexiForce sensor was performed. This sensor continuously displays the compressive force, allowing surgeons to check values on the monitor at any time. An alarm sounds if 50 gf is exceeded. We analyzed the temporal course of extraocular pressure and the relationship with patient characteristics. No visual complications were encountered in this patient series. Maximum compressive force during craniotomy was 35.8±27.2 gf, with increases typically seen when surgeons used hooks or drills. However, due to the alarm, no prolonged periods of high force were noted in any patient. Effective methods for reducing force were: (1) taking off hooks on the compressive side; (2) changing the direction of hook tension; and (3) placing cushions such as gauze under the side of the skin flap. Maximum compressive force during microsurgery was 21.8±18.4 gf, and correlated with the beginning force of microsurgery. Compressive force was greatly reduced compared to the force reported previously. The etiologies of visual disability are not fully understood, but this sensor may be helpful in reducing extraocular compression.

Effect of scalp blocks with levobupivacaine on recovery profiles after craniotomy for aneurysm clipping: a randomized, double-blind, and controlled study.

PubMed

Hwang, Jin-Young; Bang, Jae-Seung; Oh, Chang-Wan; Joo, Jin-Deok; Park, Seong-Joo; Do, Sang-Hwan; Yoo, Yong-Jae; Ryu, Jung-Hee

2015-01-01

This study was conducted to evaluate the effect of scalp blocks using levobupivacaine on recovery profiles including postoperative pain, patient-controlled analgesia (PCA) consumption, postoperative nausea and vomiting (PONV), and other adverse events in patients undergoing frontoparietal craniotomy for aneurysm clipping. Fifty-two patients scheduled for elective frontoparietal craniotomy for unruptured aneurysm clipping were enrolled. After surgery, scalp blocks were performed using normal saline (group C, n = 26) or 0.75% levobupivacaine (group L, n = 26). Postoperative pain scores and PCA consumption were recorded for 72 hours after recovery of consciousness. The time from patient recovery to the first use of PCA drug and rescue analgesics, the requirement for vasoactive agents, and adverse effects related to PCA and local anesthetics also were recorded. Postoperative pain scores and PCA consumption in group L were lower than in group C (P < .05). The time intervals from patient recovery to the first use of PCA drug (P < .001) and rescue analgesics (P = .038) was longer in group L than in group C. Additionally, less antihypertensive agent was required (P = .017), and PONV occurred less frequently (P = .039) in group L than in group C. Scalp blocks with 0.75% levobupivacaine improved recovery profiles in that it effectively lowered postoperative pain and PCA consumption without severe adverse events and also reduced the requirement for a postoperative antihypertensive agent and the incidence of PONV in patients who underwent frontoparietal craniotomy for aneurysm clipping. Copyright © 2015 Elsevier Inc. All rights reserved.

Wound healing after craniotomy: a randomized trial comparing scalp clips to artery forceps for scalp hemostasis.

PubMed

Langford, Peter; Wolfe, Rory; Danks, R Andrew

2009-12-01

In this prospective randomized clinical trial, investigators looked at wound healing after craniotomy. The hypothesis was that the self-closing plastic scalp clips used for hemostasis on the skin edge might lead to localized microscopic tissue damage and subsequent delayed wound healing. The trial consisted of 2 arms in which different methods were used to secure scalp hemostasis: 1) the routinely used plastic clips (Scalpfix, Aesculap); and 2) the older method of artery forceps placed on the galea. Participants were restricted to those > 16 years of age undergoing craniotomies expected to last > 2 hours. Repeat operations were not included. One hundred fifty patients were enrolled. They were visited at 3 and 6 weeks postoperatively by an observer blinded to the method used, and the wounds were assessed for macroscopic epithelial closure, signs of infection, and hair regrowth by using a predefined assessment scale. The results showed no significant difference in wound healing between the 2 groups at either 3 weeks (OR 0.55, 95% CI 0.27-1.11; p = 0.09) or 6 weeks (OR 0.79, 95% CI 0.39-1.58; p = 0.50). The length of operation was found to be a significant factor affecting wound healing at 6 weeks (OR/hour 0.68, 95% CI 0.51-0.92; p = 0.01). The use of Aesculap Scalpfix self-retaining plastic scalp clips on the skin edge during craniotomy surgery does not appear to affect wound healing significantly to the postoperative 6-week mark.

Aluminum reduction cell electrode

DOEpatents

Payne, J.R.

1983-09-20

The invention is directed to an anode-cathode structure for an electrolytic cell for the reduction of alumina wherein the structure is comprised of a carbon anode assembly which straddles a wedge-shaped refractory hard metal cathode assembly having steeply sloped cathodic surfaces, each cathodic surface being paired in essentially parallel planar relationship with an anode surface. The anode-cathode structure not only takes into account the structural weakness of refractory hard metal materials but also permits the changing of the RHM assembly during operation of the cell. Further, the anode-cathode structure enhances the removal of anode gas from the interpolar gap between the anode and cathode surfaces. 10 figs.

Aluminum reduction cell electrode

DOEpatents

Payne, John R.

1983-09-20

The invention is directed to an anode-cathode structure for an electrolytic cell for the reduction of alumina wherein the structure is comprised of a carbon anode assembly which straddles a wedge-shaped refractory hard metal cathode assembly having steeply sloped cathodic surfaces, each cathodic surface being paired in essentially parallel planar relationship with an anode surface. The anode-cathode structure not only takes into account the structural weakness of refractory hard metal materials but also permits the changing of the RHM assembly during operation of the cell. Further, the anode-cathode structure enhances the removal of anode gas from the interpolar gap between the anode and cathode surfaces.

Modification of the fault logic circuit of a high-energy linear accelerator to accommodate selectively coded, large-field wedges.

PubMed

Miller, R W; van de Geijn, J

1987-01-01

A modification to the fault logic circuit that controls the collimator (COLL) fault is described. This modification permits the use of large-field wedges by adding an additional input into the reference voltage that determines the fault condition. The resistor controlling the amount of additional voltage is carried on board each wedge, within the wedge plug. This allows each wedge to determine its own, individual field size limit. Additionally, if no coding resistor is provided, the factory-supplied reference voltage is used, which sets the maximum allowable field size to 15 cm. This permits the use of factory-supplied wedges in conjunction with selected, large-field wedges, allowing proper sensing of the field size maximum in all conditions.

Surgical Management of Supratentorial Intracerebral Hemorrhages: Endoscopic Versus Open Surgery.

PubMed

Eroglu, Umit; Kahilogullari, Gokmen; Dogan, Ihsan; Yakar, Fatih; Al-Beyati, Eyyub S M; Ozgural, Onur; Cohen-Gadol, Aaron A; Ugur, Hasan Caglar

2018-06-01

Intracerebral hemorrhage continues to be a major global problem. No standard treatment or surgical procedure has been identified for intracerebral hemorrhages. High morbidity and mortality rates caused by conventional approaches and the disease itself have necessitated more-invasive treatment methods. The endoscopic approach is a more minimally invasive method than craniotomy, which is another alternative surgical treatment. We compared intracerebral hematoma drainage in 2 groups of 17 patients each, treated with minimally invasive endoscopic method versus craniotomy. All the patients were treated for supratentorial spontaneous hemorrhage between December 2013 and February 2017 at the Neurosurgery Clinic of Ankara University Faculty of Medicine. We retrospectively evaluated 34 patients surgically treated between December 2013 and February 2017. All patients underwent surgery within the first 24 hours. Patients in the early surgery group had better surgical outcomes. In the neuroendoscopic group, Glasgow Coma Scale increased from 6 to 11 at 1 week postoperatively compared with 5 to 9 in the craniotomy group. Minimally invasive endoscopic hematoma evacuation may be a good alternative surgical method for treating supratentorial spontaneous cerebral hematomas. Copyright © 2018 Elsevier Inc. All rights reserved.

The Potential Benefits of Awake Craniotomy for Brain Tumor Resection: An Anesthesiologist's Perspective.

PubMed

Meng, Lingzhong; Berger, Mitchel S; Gelb, Adrian W

2015-10-01

Awake craniotomy for brain tumor resection is becoming a standard of care for lesions residing within or in close proximity to regions presumed to have language or sensorimotor function. Evidence shows an improved outcome including greater extent of resection, fewer late neurological deficits, shorter hospital stay, and longer survival after awake brain tumor resection compared with surgery under general anesthesia. The surgeon's ability to maximize tumor resection within the constraint of preserving neurological function by intraoperative stimulation mapping in an awake patient is credited for this advantageous result. It is possible that the care provided by anesthesiologists, especially the avoidance of certain components of general endotracheal anesthesia, may also be important in the outcome of awake brain tumor resection. We present our interpretation of the evidence that we believe substantiates this proposition. However, due to the lack of direct evidence based on randomized-controlled trials and the heterogeneity of anesthetic techniques used for awake craniotomy, our perspective is largely speculative and hypothesis generating that needs to be validated or refuted by future quality research.

Effects of altering heel wedge properties on gait with the Intrepid Dynamic Exoskeletal Orthosis.

PubMed

Ikeda, Andrea J; Fergason, John R; Wilken, Jason M

2018-06-01

The Intrepid Dynamic Exoskeletal Orthosis is a custom-made dynamic response carbon fiber device. A heel wedge, which sits in the shoe, is an integral part of the orthosis-heel wedge-shoe system. Because the device restricts ankle movement, the system must compensate to simulate plantarflexion and allow smooth forward progression during gait. To determine the influence of wedge height and durometer on the walking gait of individuals using the Intrepid Dynamic Exoskeletal Orthosis. Repeated measures. Twelve individuals walked over level ground with their Intrepid Dynamic Exoskeletal Orthosis and six different heel wedges of soft or firm durometer and 1, 2, or 3 cm height. Center of pressure velocity, joint moments, and roll-over shape were calculated for each wedge. Height and durometer significantly affected time to peak center of pressure velocity, time to peak internal dorsiflexion and knee extension moments, time to ankle moment zero crossing, and roll-over shape center of curvature anterior-posterior position. Wedge height had a significant influence on peak center of pressure velocity, peak dorsiflexion moment, time to peak knee extension moment, and roll-over shape radius and vertical center of curvature. Changes in wedge height and durometer systematically affected foot loading. Participants preferred wedges which produced ankle moment zero crossing timing, peak internal knee extension moment timing, and roll-over shape center of curvature anterior-posterior position close to that of able-bodied individuals. Clinical relevance Adjusting the heel wedge is a simple, straightforward way to adjust the orthosis-heel wedge-shoe system. Changing wedge height and durometer significantly alters loading of the foot and has great potential to improve an individual's gait.

Microtopographic control on the ground thermal regime in ice wedge polygons

NASA Astrophysics Data System (ADS)

Abolt, Charles J.; Young, Michael H.; Atchley, Adam L.; Harp, Dylan R.

2018-06-01

The goal of this research is to constrain the influence of ice wedge polygon microtopography on near-surface ground temperatures. Ice wedge polygon microtopography is prone to rapid deformation in a changing climate, and cracking in the ice wedge depends on thermal conditions at the top of the permafrost; therefore, feedbacks between microtopography and ground temperature can shed light on the potential for future ice wedge cracking in the Arctic. We first report on a year of sub-daily ground temperature observations at 5 depths and 9 locations throughout a cluster of low-centered polygons near Prudhoe Bay, Alaska, and demonstrate that the rims become the coldest zone of the polygon during winter, due to thinner snowpack. We then calibrate a polygon-scale numerical model of coupled thermal and hydrologic processes against this dataset, achieving an RMSE of less than 1.1 °C between observed and simulated ground temperature. Finally, we conduct a sensitivity analysis of the model by systematically manipulating the height of the rims and the depth of the troughs and tracking the effects on ice wedge temperature. The results indicate that winter temperatures in the ice wedge are sensitive to both rim height and trough depth, but more sensitive to rim height. Rims act as preferential outlets of subsurface heat; increasing rim size decreases winter temperatures in the ice wedge. Deeper troughs lead to increased snow entrapment, promoting insulation of the ice wedge. The potential for ice wedge cracking is therefore reduced if rims are destroyed or if troughs subside, due to warmer conditions in the ice wedge. These findings can help explain the origins of secondary ice wedges in modern and ancient polygons. The findings also imply that the potential for re-establishing rims in modern thermokarst-affected terrain will be limited by reduced cracking activity in the ice wedges, even if regional air temperatures stabilize.

Dose to the contralateral breast: a comparison of two techniques using the enhanced dynamic wedge versus a standard wedge.

PubMed

Warlick, W B; O'Rear, J H; Earley, L; Moeller, J H; Gaffney, D K; Leavitt, D D

1997-01-01

The dose to the contralateral breast has been associated with an increased risk of developing a second breast malignancy. Varying techniques have been devised and described in the literature to minimize this dose. Metal beam modifiers such as standard wedges are used to improve the dose distribution in the treated breast, but unfortunately introduce an increased scatter dose outside the treatment field, in particular to the contralateral breast. The enhanced dynamic wedge is a means of remote wedging created by independently moving one collimator jaw through the treatment field during dose delivery. This study is an analysis of differing doses to the contralateral breast using two common clinical set-up techniques with the enhanced dynamic wedge versus the standard metal wedge. A tissue equivalent block (solid water), modeled to represent a typical breast outline, was designed as an insert in a Rando phantom to simulate a standard patient being treated for breast conservation. Tissue equivalent material was then used to complete the natural contour of the breast and to reproduce appropriate build-up and internal scatter. Thermoluminescent dosimeter (TLD) rods were placed at predetermined distances from the geometric beam's edge to measure the dose to the contralateral breast. A total of 35 locations were used with five TLDs in each location to verify the accuracy of the measured dose. The radiation techniques used were an isocentric set-up with co-planar, non divergent posterior borders and an isocentric set-up with a half beam block technique utilizing the asymmetric collimator jaw. Each technique used compensating wedges to optimize the dose distribution. A comparison of the dose to the contralateral breast was then made with the enhanced dynamic wedge vs. the standard metal wedge. The measurements revealed a significant reduction in the contralateral breast dose with the enhanced dynamic wedge compared to the standard metal wedge in both set-up techniques. The dose was measured at varying distances from the geometric field edge, ranging from 2 to 8 cm. The average dose with the enhanced dynamic wedge was 2.7-2.8%. The average dose with the standard wedge was 4.0-4.7%. Thermoluminescent dosimeter measurements suggest an increase in both scattered electrons and photons with metal wedges. The enhanced dynamic wedge is a practical clinical advance which improves the dose distribution in patients undergoing breast conservation while at the same time minimizing dose to the contralateral breast, thereby reducing the potential carcinogenic effects.

Ultrasonic fluid densitometer for process control

DOEpatents

Greenwood, Margaret S.

2000-01-01

The present invention is an ultrasonic fluid densitometer that uses at least one pair of transducers for transmitting and receiving ultrasonic signals internally reflected within a material wedge. A temperature sensor is provided to monitor the temperature of the wedge material. Density of a fluid is determined by immersing the wedge into the fluid and measuring reflection of ultrasound at the wedge-fluid interface and comparing a transducer voltage and wedge material temperature to a tabulation as a function of density.

Challenges in pediatric neuroanesthesia: awake craniotomy, intraoperative magnetic resonance imaging, and interventional neuroradiology.

PubMed

McClain, Craig D; Landrigan-Ossar, Mary

2014-03-01

This article gives a review of 3 challenges in caring for children undergoing neurosurgical and neurointerventional procedures. Anesthesiologists may have experience with certain aspects of these situations but may not have extensive experience with each clinical setting. This review addresses issues with awake craniotomy, intraoperative magnetic resonance imaging, and neurointerventional procedures in children with neurologic disease. Familiarization with these complex clinical scenarios and their unique considerations allows the anesthesiologist to deliver optimal care and helps facilitate the best possible outcome for these patients. Copyright © 2014 Elsevier Inc. All rights reserved.

How I do it: surgical ligation of craniocervical junction dural AV fistulas.

PubMed

Sorenson, Thomas J; La Pira, Biagia; Hughes, Joshua; Lanzino, Giuseppe

2017-08-01

Dural arteriovenous fistulas (DAVFs) of the craniocervical junction are uncommon vascular lesions, which often require surgical treatment even in the endovascular era. Most commonly, the fistula is placed laterally, and surgical ligation is performed through a lateral suboccipital craniotomy. After dural opening, the area is inspected, and the arterialized vein is identified emerging from the dura, often adjacent to the entry point of the vertebral artery, and ligated. A far lateral craniotomy is the authors' preferred surgical approach for accessing and treating dural arteriovenous fistulas of the craniocervical junction that cannot be reached endovascularly.

[Craniotomy without trichotomy: analysis of 640 cases].

PubMed

Dvilevicius, Amylcar E; Machado, Silvio; do Rêgo, José Iram M; Santos, Daniel Souza; Pietrowski, Fábio; Reis, Arnaldo Dias

2004-03-01

The hair shaving in preparation for neurosurgery is frequently used in most of neurosurgical centers to perform craniotomy. We question about its necessity after our retrospective analysis of 640 patients undergoing cranial procedures without previous hair shaving. We had the overall surgical wound infection rate of 1.09%, not higher than tricotomy in the review of the literature. In 7 cases with infection, 3 patients were undergoing to CSF shunts, 3 patients had head injury, and one had brain tumor. The technique for preparing skin and hair for cranial procedures, its advantages and disadvantages are described and discussed.

Isolating active orogenic wedge deformation in the southern Subandes of Bolivia

NASA Astrophysics Data System (ADS)

Weiss, Jonathan R.; Brooks, Benjamin A.; Foster, James H.; Bevis, Michael; Echalar, Arturo; Caccamise, Dana; Heck, Jacob; Kendrick, Eric; Ahlgren, Kevin; Raleigh, David; Smalley, Robert; Vergani, Gustavo

2016-08-01

A new GPS-derived surface velocity field for the central Andean backarc permits an assessment of orogenic wedge deformation across the southern Subandes of Bolivia, where recent studies suggest that great earthquakes (>Mw 8) are possible. We find that the backarc is not isolated from the main plate boundary seismic cycle. Rather, signals from subduction zone earthquakes contaminate the velocity field at distances greater than 800 km from the Chile trench. Two new wedge-crossing velocity profiles, corrected for seasonal and earthquake affects, reveal distinct regions that reflect (1) locking of the main plate boundary across the high Andes, (2) the location of and loading rate at the back of orogenic wedge, and (3) an east flank velocity gradient indicative of décollement locking beneath the Subandes. Modeling of the Subandean portions of the profiles indicates along-strike variations in the décollement locked width (WL) and wedge loading rate; the northern wedge décollement has a WL of ~100 km while accumulating slip at a rate of ~14 mm/yr, whereas the southern wedge has a WL of ~61 km and a slip rate of ~7 mm/yr. When compared to Quaternary estimates of geologic shortening and evidence for Holocene internal wedge deformation, the new GPS-derived wedge loading rates may indicate that the southern wedge is experiencing a phase of thickening via reactivation of preexisting internal structures. In contrast, we suspect that the northern wedge is undergoing an accretion or widening phase primarily via slip on relatively young thrust-front faults.

The use of sternal wedge osteotomy in pectus surgery: when is it necessary?

PubMed

Kara, Murat; Gundogdu, Ahmet Gokhan; Kadioglu, Salih Zeki; Cayirci, Ertug Can; Taskin, Necati

2016-09-01

The Ravitch procedure is a well-established surgical procedure for correction of chest wall deformities. Sternal wedge osteotomy is an important part of this procedure. We studied the incidence of wedge osteotomy with respect to the type of chest wall deformity in patients undergoing surgical correction with the use of a recently developed chest wall stabilization system. A total of 47 patients, 39 (83%) male and 8 (17%) female with a mean age of 14.9 ± 2.1 years, underwent the Ravitch procedure. Twenty-four (51.1%) had pectus carinatum, 19 (40.4%) had pectus excavatum, and 4 (8.5%) had pectus arcuatum. A conventional or oblique sternal wedge osteotomy was performed as indicated, followed by chest wall stabilization using the MedXpert system. Of the 47 patients, 27 (57.4%) had a sternal wedge osteotomy. All cases of pectus arcuatum and redo cases underwent sternal wedge osteotomy. Pectus excavatum cases tended to have a greater incidence of wedge osteotomy compared to pectus carinatum cases (68.4% vs. 41.7%, p = 0.052). Patients with more resected ribs had a greater rate of wedge osteotomy (63.4%) compared to those with fewer resected ribs (16.7%, p = 0.043). A sternal wedge osteotomy is more commonly performed in patients with pectus excavatum compared to those with pectus carinatum. All redo and pectus arcuatum cases need a wedge osteotomy for proper correction. Wedge osteotomy is very likely in more aggressive corrections with more rib resections. © The Author(s) 2016.

Why We Don't Collaborate in Response to Climate Change: The Knowledge Deficit, Co-Production, and the Future of the IPCC.

NASA Astrophysics Data System (ADS)

Cook, B. R.; Overpeck, J. T.

2014-12-01

Scientific knowledge production is based on recognizing and filling knowledge deficits or 'gaps' in understanding, but for climate adaptation and mitigation, the applicability of this approach is questionable. The Intergovernmental Panel on Climate Change (IPCC) mandate is an example of this type of 'gap filling,' in which the elimination of uncertainties is presumed to enable rational decision making for individuals and rational governance for societies. Presumed knowledge deficits, though, are unsuited to controversial problems with social, cultural, and economic dimensions; likewise, communication to educate is an ineffective means of inciting behavioural change. An alternative is needed, particularly given the economic, social, and political scale that action on climate change requires. We review the 'deficit-education framing' and show how it maintains a wedge between those affected and those whose knowledge is required. We then review co-production to show how natural and social scientists, as well as the IPCC, might more effectively proceed.

Ultrasonic fluid densitometry and densitometer

DOEpatents

Greenwood, Margaret S.; Lail, Jason C.

1998-01-01

The present invention is an ultrasonic fluid densitometer that uses a material wedge having an acoustic impedance that is near the acoustic impedance of the fluid, specifically less than a factor of 11 greater than the acoustic impedance of the fluid. The invention also includes a wedge having at least two transducers for transmitting and receiving ultrasonic signals internally reflected within the material wedge. Density of a fluid is determined by immersing the wedge into the fluid and measuring reflection of ultrasound at the wedge-fluid interface.

Ultrasonic fluid densitometry and densitometer

DOEpatents

Greenwood, M.S.; Lail, J.C.

1998-01-13

The present invention is an ultrasonic fluid densitometer that uses a material wedge having an acoustic impedance that is near the acoustic impedance of the fluid, specifically less than a factor of 11 greater than the acoustic impedance of the fluid. The invention also includes a wedge having at least two transducers for transmitting and receiving ultrasonic signals internally reflected within the material wedge. Density of a fluid is determined by immersing the wedge into the fluid and measuring reflection of ultrasound at the wedge-fluid interface. 6 figs.

Laser-based linear and nonlinear guided elastic waves at surfaces (2D) and wedges (1D).

PubMed

Hess, Peter; Lomonosov, Alexey M; Mayer, Andreas P

2014-01-01

The characteristic features and applications of linear and nonlinear guided elastic waves propagating along surfaces (2D) and wedges (1D) are discussed. Laser-based excitation, detection, or contact-free analysis of these guided waves with pump-probe methods are reviewed. Determination of material parameters by broadband surface acoustic waves (SAWs) and other applications in nondestructive evaluation (NDE) are considered. The realization of nonlinear SAWs in the form of solitary waves and as shock waves, used for the determination of the fracture strength, is described. The unique properties of dispersion-free wedge waves (WWs) propagating along homogeneous wedges and of dispersive wedge waves observed in the presence of wedge modifications such as tip truncation or coatings are outlined. Theoretical and experimental results on nonlinear wedge waves in isotropic and anisotropic solids are presented. Copyright © 2013 Elsevier B.V. All rights reserved.

Double wedge prism based beam deflector for precise laser beam steering

NASA Astrophysics Data System (ADS)

Tyszka, Krzysztof; Dobosz, Marek; Bilaszewski, Tomasz

2018-02-01

Aiming to increase laser beam pointing stability required in interferometric measurements, we designed a laser beam deflector intended for active laser beam stabilization systems. The design is based on two wedge-prisms: the deflecting wedge driven by a tilting piezo-platform and the fixed wedge to compensate initial beam deflection. Our design allows linear beam steering, independently in the horizontal or vertical direction, with resolution of less than 1 μrad in a range of more than 100 μrad, and no initial deflection of the beam. Moreover, the ratio of the output beam deflection angle and the wedge tilt angle is less than 0.1; therefore, the noise influence is significantly reduced in comparison to standard mirror-based deflectors. The theoretical analyses support the designing process and can serve as a guide to wedge-prism selection. The experimental results are in agreement with theory and confirm the advantages of the presented double wedge system.

Pitch-catch only ultrasonic fluid densitometer

DOEpatents

Greenwood, M.S.; Harris, R.V.

1999-03-23

The present invention is an ultrasonic fluid densitometer that uses a material wedge and pitch-catch only ultrasonic transducers for transmitting and receiving ultrasonic signals internally reflected within the material wedge. Density of a fluid is determined by immersing the wedge into the fluid and measuring reflection of ultrasound at the wedge-fluid interface. 6 figs.

Pitch-catch only ultrasonic fluid densitometer

DOEpatents

Greenwood, Margaret S.; Harris, Robert V.

1999-01-01

The present invention is an ultrasonic fluid densitometer that uses a material wedge and pitch-catch only ultrasonic transducers for transmitting and receiving ultrasonic signals internally reflected within the material wedge. Density of a fluid is determined by immersing the wedge into the fluid and measuring reflection of ultrasound at the wedge-fluid interface.

Ice Particle Impacts on a Moving Wedge

NASA Technical Reports Server (NTRS)

Vargas, Mario; Struk, Peter M.; Kreeger, Richard E.; Palacios, Jose; Iyer, Kaushik A.; Gold, Robert E.

2014-01-01

This work presents the results of an experimental study of ice particle impacts on a moving wedge. The experiment was conducted in the Adverse Environment Rotor Test Stand (AERTS) facility located at Penn State University. The wedge was placed at the tip of a rotating blade. Ice particles shot from a pressure gun intercepted the moving wedge and impacted it at a location along its circular path. The upward velocity of the ice particles varied from 7 to 12 meters per second. Wedge velocities were varied from 0 to 120 meters per second. Wedge angles tested were 0 deg, 30 deg, 45 deg, and 60 deg. High speed imaging combined with backlighting captured the impact allowing observation of the effect of velocity and wedge angle on the impact and the post-impact fragment behavior. It was found that the pressure gun and the rotating wedge could be synchronized to consistently obtain ice particle impacts on the target wedge. It was observed that the number of fragments increase with the normal component of the impact velocity. Particle fragments ejected immediately after impact showed velocities higher than the impact velocity. The results followed the major qualitative features observed by other researchers for hailstone impacts, even though the reduced scale size of the particles used in the present experiment as compared to hailstones was 4:1.

Wedge gate valves selecting essentials in pipeline systems designing based on permissible operation parameters

NASA Astrophysics Data System (ADS)

Zakirnichnaya, M. M.; Kulsharipov, I. M.

2017-10-01

Wedge gate valves are widely used at the fuel and energy complex enterprises. The pipeline valves manufacturers indicate the safe operation resource according to the current regulatory and technical documentation. In this case, the resource value of the valve body strength calculation results is taken into consideration as the main structural part. However, it was determined that the wedge gate valves fail before the assigned resource due to the occurrence of conditions under which the wedge breaks in the hooks and, accordingly, the sealing integrity is not ensured. In this regard, it became necessary to assess the conditions under which the resource should be assigned not only to the valve body, but also to take into account the wedge durability. For this purpose, wedge resource calculations were made using the example of ZKL2 250-25 and ZKL2 300-25 valves using the ABAQUS software package FE-SAFE module under the technological parameters influence on the basis of their stressstrain state calculation results. Operating conditions, under which the wedge resource value is lower than the one set by the manufacturer, were determined. A technique for limiting the operating parameters for ensuring the wedge durability during the wedge gate valve assigned resource is proposed.

Effects of Lateral and Medial Wedged Insoles on Knee and Ankle Internal Joint Moments During Walking in Healthy Men.

PubMed

Fukuchi, Claudiane A; Lewinson, Ryan T; Worobets, Jay T; Stefanyshyn, Darren J

2016-11-01

Wedged insoles have been used to treat knee pathologies and to prevent injuries. Although they have received much attention for the study of knee injury, the effects of wedges on ankle joint biomechanics are not well understood. This study sought to evaluate the immediate effects of lateral and medial wedges on knee and ankle internal joint loading and center of pressure (CoP) in men during walking. Twenty-one healthy men walked at 1.4 m/sec in five footwear conditions: neutral, 6° (LW6) and 9° (LW9) lateral wedges, and 6° (MW6) and 9° (MW9) medial wedges. Peak internal knee abduction moments and angular impulses, internal ankle inversion moments and angular impulses, and mediolateral CoP were analyzed. Analysis of variance with post hoc analysis and Pearson correlations were performed to detect differences between conditions. No differences in internal knee joint loading were found between neutral and any of the wedge conditions. However, as the wedge angle increased from medial to lateral, the internal ankle inversion moment (LW6: P = .020; LW9: P < .001; MW6: P = .046; MW9: P < .001) and angular impulse (LW9: P = .012) increased, and the CoP shifted laterally (LW9: P < .001) and medially (MW9: P < .001) compared with the neutral condition. Neither lateral nor medial wedges were effective in altering internal knee joint loading during walking. However, the greater internal ankle inversion moment and angular impulse observed with lateral wedges could lead to a higher risk of ankle injury. Thus, caution should be taken when lateral wedges need to be prescribed.

The influence of physical wedges on penumbra and in-field dose uniformity in ocular proton beams.

PubMed

Baker, Colin; Kacperek, Andrzej

2016-04-01

A physical wedge may be partially introduced into a proton beam when treating ocular tumours in order to improve dose conformity to the distal border of the tumour and spare the optic nerve. Two unwanted effects of this are observed: a predictable broadening of the beam penumbra on the wedged side of the field and, less predictably, an increase in dose within the field along a relatively narrow volume beneath the edge (toe) of the wedge, as a result of small-angle proton scatter. Monte Carlo simulations using MCNPX and direct measurements with radiochromic (GAFCHROMIC(®) EBT2) film were performed to quantify these effects for aluminium wedges in a 60 MeV proton beam as a function of wedge angle and position of the wedge relative to the patient. For extreme wedge angles (60° in eye tissue) and large wedge-to-patient distances (70 mm in this context), the 90-10% beam penumbra increased from 1.9 mm to 9.1 mm. In-field dose increases from small-angle proton scatter were found to contribute up to 21% additional dose, persisting along almost the full depth of the spread-out-Bragg peak. Profile broadening and in-field dose enhancement are both minimised by placing the wedge as close as possible to the patient. Use of lower atomic number wedge materials such as PMMA reduce the magnitude of both effects as a result of a reduced mean scattering angle per unit energy loss; however, their larger physical size and greater variation in density are undesirable. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Local transmural action potential gradients are absent in the isolated, intact dog heart but present in the corresponding coronary-perfused wedge.

PubMed

Boukens, Bastiaan J; Meijborg, Veronique M F; Belterman, Charly N; Opthof, Tobias; Janse, Michiel J; Schuessler, Richard B; Coronel, Ruben; Efimov, Igor R

2017-05-01

The left ventricular (LV) coronary-perfused canine wedge preparation is a model commonly used for studying cardiac repolarization. In wedge studies, transmembrane potentials typically are recorded; whereas, extracellular electrical recordings are commonly used in intact hearts. We compared electrically measured activation recovery interval (ARI) patterns in the intact heart with those recorded at the same location in the LV wedge preparation. We also compared electrically recorded and optically obtained ARIs in the LV wedge preparation. Five Langendorff-perfused canine hearts were paced from the right atrium. Local activation and repolarization times were measured with eight transmural needle electrodes. Subsequently, left ventricular coronary-perfused wedge preparations were prepared from these hearts while the electrodes remained in place. Three electrodes remained at identical positions as in the intact heart. Both electrograms and optical action potentials were recorded (pacing cycle length 400-4000 msec) and activation and repolarization patterns were analyzed. ARIs found in the subepicardium were shorter than in the subendocardium in the LV wedge preparation but not in the intact heart. The transmural ARI gradient recorded at the cut surface of the wedge was not different from that recorded internally. ARIs recorded internally and at the cut surface in the LV wedge preparation, both correlated with optically recorded action potentials. ARI and RT gradients in the LV wedge preparation differed from those in the intact canine heart, implying that those observations in human LV wedge preparations also should be extrapolated to the intact human heart with caution. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Modeling the Evolution of Localized Strain in Orogenic Wedges: From Short-term Deformation to Long-term Tectonic States

NASA Astrophysics Data System (ADS)

Weiss, J. R.; Ito, G.; Brooks, B. A.; Olive, J. A. L.; Foster, J. H.; Howell, S. M.

2015-12-01

Some of the most destructive earthquakes on Earth are associated with active orogenic wedges. Despite a sound understanding of the basic mechanics that govern whole wedge structure over geologic time scales and a growing body of studies that have characterized the deformation associated with historic to recent earthquakes, first order questions remain about the linkage of the two sets of processes at the intermediate seismotectonic timescales. Numerical models have the power to test the effects of specific mechanical conditions on the evolution of observables at active orogenic wedges. Here we use a two-dimensional, continuum mechanics-based, finite difference method with a visco-elasto-plastic rheology coupled with surface processes to investigate the spatiotemporal distribution of deformation during wedge growth. The model simulates the contraction of a crustal layer overlying a weak base (décollement) against a rigid backstop and the spontaneous nucleation and evolution of fault zones due to cohesive, Mohr-Coulomb failure with strain weakening. Consistent with critical wedge theory, the average slope across the wedge is controlled by the relative frictional strengths of the wedge and décollement. Initial calculations predict changes in wedge deformation on short geologic timescales (103-105yrs) that involve episodes of widening as new, foreland-verging thrusts nucleate near the surface beyond the wedge toe and propagate down-dip to intersect the décollement. All the while, the wedge thickens via slip on older, internal fault zones. The aim of this study is to identify the parameters controlling the timescales of 1) episodic widening versus thickening and 2) nucleation and life-span of individual fault zones. These are initial steps needed to link earthquake observations to the long-term tectonic states inferred at various orogenic belts around the world.

Minimally Invasive Alternative Approaches to Pterional Craniotomy: A Systematic Review of the Literature.

PubMed

Rychen, Jonathan; Croci, Davide; Roethlisberger, Michel; Nossek, Erez; Potts, Matthew; Radovanovic, Ivan; Riina, Howard; Mariani, Luigi; Guzman, Raphael; Zumofen, Daniel W

2018-05-01

Minimally invasive alternatives to the pterional craniotomy include the minipterional and the supraorbital craniotomy (SOC). The latter is performed via either an eyebrow or an eyelid skin incision. The purpose of this systematic review was to analyze the type and the incidence of approach-related complications of these so-called "keyhole craniotomies". We review pertinent articles retrieved by search in the PubMed/Medline database. Inclusion criteria were all full-text articles, abstracts, and posters in English, up to 2016, reporting clinical results. A total of 105 articles containing data on 5837 surgeries performed via a minipterional or either of the 2 variants of the SOC met the eligibility criteria. Pain on mastication was the most commonly reported approach-related complication of the minipterional approach, and occurred in 7.5% of cases. Temporary palsy of the frontal branch of the facial nerve and temporary supraorbital hypesthesia were associated with the SOC eyebrow variant, and occurred in 6.5%, respectively in 3.6% of cases. Transient postoperative periorbital edema and transient ophthalmoparesis occurred in 36.8% and 17.4% of cases, respectively, when the SOC was performed via an eyelid skin incision. The risk of occurrence of the latter 2 complications was related to the removal of the orbital rim, which is an obligatory part of the SOC approach through the eyelid but optional with the SOC eyebrow variant. Each of the 3 keyhole approaches has a specific set and incidence of approach-related complications. It is essential to be aware of these complications to make the safest individual choice. Copyright © 2018 Elsevier Inc. All rights reserved.

Comparative Analysis of the Mini-pterional and Supraorbital Keyhole Craniotomies for Unruptured Aneurysms with Numeric Measurements of Their Geometric Configurations.

PubMed

Kang, Ho-Jun; Lee, Yoon-Soo; Suh, Sang-Jun; Lee, Jeong-Ho; Ryu, Kee-Young; Kang, Dong-Gee

2013-03-01

Keyhole craniotomy is a modification of pterional craniotomy that allows for use of a minimally invasive approach toward cerebral aneurysms. Currently, mini-pterional (MPKC) and supraorbital keyhole craniotomies (SOKC) are commonly used. In this study, we measured and compared the geometric configurations of surgical exposure provided by MPKC and SOKC. Nine patients underwent MPKC and four underwent SOKC. Their postoperative contrast-enhanced brain computed tomographic scans were evaluated. The transverse and longitudinal diameters and areas of exposure were measured. The locations of the anterior communicating artery, bifurcation of the middle cerebral artery (MCAB), and the internal carotid artery (ICA) terminal were identified, and the working angles and depths for these targets were measured. No significant differences in the transverse diameters of exposure were observed between MPKC and SOKC. However, the longitudinal diameters and the areas were significantly larger, by 1.5 times in MPKC. MPKC provided larger operable working angles for the targets. The angles by MPKC, particularly for the MCAB, reached up to 1.9-fold of those by SOKC. Greater working depths were required in order to reach the targets by SOKC, and the differences were the greatest in the MCAB by 1.6-fold. MPKC provides larger exposure than SOKC with a similar length of skin incision. MPKC allows for use of a direct transsylvian approach, and exposes the target in a wide working angle within a short distance. Despite some limitations in exposure, SOKC is suitable for a direct subfrontal approach, and provides a more anteromedial and basal view. MCAB and posteriorly directing ICA terminal aneurysms can be good candidates for MPKC.

Tension pneumocephalus following suboccipital sitting craniotomy in the pediatric population.

PubMed

Daszkiewicz, P; Dziedzic, D

Sitting craniotomy often results in entrapment of air in fluid-filled intracranial cavities. Gas under pressure exerts a deleterious effect on adjacent nervous tissue, resulting in clinical deterioration. To assess the incidence of tension pneumocephalus (TP) and to define risk factors associated therewith. Analysis included 100 consecutive patients (57 boys, 43 girls, mean age 9.7 y) undergoing suboccipital sitting craniotomy since 2012 to 2014. In our material (n=100) TP was seen in 7 cases, asymptomatic pneumocephalus (AP) in 77 and no pneumocephalus (NP) in 16. Tumor types encountered were typical for pediatric population. In the TP group (n=7) the ratio of low-grade to high-grade tumors was 5:2, in the AP group (n=77) 2:1 and in the NP group (n=16) 1:1. Preoperative hydrocephalus was present in 21 cases (21%, mean incidence), thereof 3 in the TP group (3/7; 42.8%), 12 in AP group (12/77; 15.5%) and 6 in the NP group (6/16; 37.5%). All TP patients received an emergency external drainage, thereof 4 required a permanent ventriculo-peritoneal shunt (57.1%), while AP and NP patients combined (n=93) required a permanent shunt in 4 cases only (4.3%). TP-associated morbidity (n=2) consisted in a significant deterioration of neurological condition. TP is a relatively rare but potentially serious complication of suboccipital sitting craniotomy. Risk factors for TP are low-grade tumor and pre-existing long-standing hydrocephalus. TP requires emergency decompression by temporary external drainage. TP patients significantly more often require a permanent CSF shunt. Copyright © 2017. Published by Elsevier Urban & Partner Sp. z o.o.

Surgical site infections following craniotomy focusing on possible post-operative acquisition of infection: prospective cohort study.

PubMed

Sneh-Arbib, O; Shiferstein, A; Dagan, N; Fein, S; Telem, L; Muchtar, E; Eliakim-Raz, N; Rubinovitch, B; Rubin, G; Rappaport, Z H; Paul, M

2013-12-01

Neurosurgery is characterized by a prolonged risk period for surgical site infection (SSI), mainly related to the presence of cerebrospinal fluid (CSF) drains. We aimed to examine factors associated with post-neurosurgical SSIs, focusing on post-operative factors. A prospective cohort study was conducted in a single center over a period of 18 months in Israel. Included were adult patients undergoing clean or clean-contaminated craniotomy, including craniotomies with external CSF drainage or shunts. SSIs were defined by the Centers for Disease Control and Prevention (CDC) criteria for healthcare-associated infections. All patients were followed up for 90 days and those with foreign body insertion for 1 year. We compared patients with and without SSI. A multivariable regression analysis for SSI was conducted including uncorrelated variables significantly associated with SSI. A total of 502 patients were included, with 138 (27.5%) undergoing emergent or urgent craniotomy. The overall SSI rate was 5.6% (28 patients), of which 3.2% (16 patients) were intracerebral. Non-elective surgery, external CSF drainage/monitoring devices, re-operation, and post-operative respiratory failure were independently associated with subsequent SSI. External CSF devices was the only significant risk factor for intracerebral SSIs (p < 0.001). Internal shunts or other foreign body insertions were not associated with SSIs. A phenotypically identical isolate to that causing the SSI was isolated from respiratory secretions prior to the SSI in 4/9 patients with microbiologically documented intracerebral SSIs. Patients with SSIs had longer hospital stay, poorer functional capacity on discharge, and higher 90-day mortality. We raise the possibility of post-operative infection acquisition through external CSF devices. Standard operating procedures for their maintenance are necessary.

Comparison of endoscopic evacuation, stereotactic aspiration and craniotomy for the treatment of supratentorial hypertensive intracerebral haemorrhage: study protocol for a randomised controlled trial.

PubMed

Xu, Xinghua; Zheng, Yi; Chen, Xiaolei; Li, Fangye; Zhang, Huaping; Ge, Xin

2017-06-28

Hypertensive intracerebral haemorrhage (HICH) is the most common form of haemorrhagic stroke with the highest morbidity and mortality of all stroke types. The choice of surgical or conservative treatment for patients with HICH remains controversial. In recent years, minimally invasive surgeries, such as endoscopic evacuation and stereotactic aspiration, have been attempted for haematoma removal and offer promise. However, research evidence on the benefits of endoscopic evacuation or stereotactic aspiration is still insufficient. A multicentre, randomised controlled trial will be conducted to compare the efficacy of endoscopic evacuation, stereotactic aspiration and craniotomy in the treatment of supratentorial HICH. About 1350 eligible patients from 10 neurosurgical centres will be randomly assigned to an endoscopic group, a stereotactic group and a craniotomy group at a 1:1:1 ratio. Randomisation is undertaken using a 24-h randomisation service accessed by telephone or the Internet. All patients will receive the corresponding surgery based on their grouping. They will be followed-up at 1, 3 and 6 months after surgery. The primary outcome is the modified Rankin Scale at 6-month follow-up. Secondary outcomes include: haematoma clearance rate; Glasgow Coma Scale 7 days after surgery; rebleeding rate; intracranial infection rate; hospitalisation time; mortality at 1 month and 3 months after surgery; the Barthel Index and the WHO quality of life at 3 months and 6 months after surgery. The trial aims to investigate whether endoscopic evacuation and stereotactic aspiration could improve the outcome of supratentorial HICH compared with craniotomy. The trial will help to determine the best surgical method for the treatment of supratentorial HICH. ClinicalTrials.gov, ID: NCT02811614 . Registered on 20 June 2016.

Rapid and minimum invasive functional brain mapping by real-time visualization of high gamma activity during awake craniotomy.

PubMed

Ogawa, Hiroshi; Kamada, Kyousuke; Kapeller, Christoph; Hiroshima, Satoru; Prueckl, Robert; Guger, Christoph

2014-11-01

Electrocortical stimulation (ECS) is the gold standard for functional brain mapping during an awake craniotomy. The critical issue is to set aside enough time to identify eloquent cortices by ECS. High gamma activity (HGA) ranging between 80 and 120 Hz on electrocorticogram is assumed to reflect localized cortical processing. In this report, we used real-time HGA mapping and functional neuronavigation integrated with functional magnetic resonance imaging (fMRI) for rapid and reliable identification of motor and language functions. Four patients with intra-axial tumors in their dominant hemisphere underwent preoperative fMRI and lesion resection with an awake craniotomy. All patients showed significant fMRI activation evoked by motor and language tasks. During the craniotomy, we recorded electrocorticogram activity by placing subdural grids directly on the exposed brain surface. Each patient performed motor and language tasks and demonstrated real-time HGA dynamics in hand motor areas and parts of the inferior frontal gyrus. Sensitivity and specificity of HGA mapping were 100% compared with ECS mapping in the frontal lobe, which suggested HGA mapping precisely indicated eloquent cortices. We found different HGA dynamics of language tasks in frontal and temporal regions. Specificities of the motor and language-fMRI did not reach 85%. The results of HGA mapping was mostly consistent with those of ECS mapping, although fMRI tended to overestimate functional areas. This novel technique enables rapid and accurate identification of motor and frontal language areas. Furthermore, real-time HGA mapping sheds light on underlying physiological mechanisms related to human brain functions. Copyright © 2014 Elsevier Inc. All rights reserved.

Awake Craniotomy Anesthesia: A Comparison of the Monitored Anesthesia Care and Asleep-Awake-Asleep Techniques.

PubMed

Eseonu, Chikezie I; ReFaey, Karim; Garcia, Oscar; John, Amballur; Quiñones-Hinojosa, Alfredo; Tripathi, Punita

2017-08-01

Commonly used sedation techniques for an awake craniotomy include monitored anesthesia care (MAC), using an unprotected airway, and the asleep-awake-asleep (AAA) technique, using a partially or totally protected airway. We present a comparative analysis of the MAC and AAA techniques, evaluating anesthetic management, perioperative outcomes, and complications in a consecutive series of patients undergoing the removal of an eloquent brain lesion. Eighty-one patients underwent awake craniotomy for an intracranial lesion over a 9-year period performed by a single-surgeon and a team of anesthesiologists. Fifty patients were treated using the MAC technique, and 31 were treated using the AAA technique. A retrospective analysis evaluated anesthetic management, intraoperative complications, postoperative outcomes, pain management, and complications. The MAC and AAA groups had similar preoperative patient and tumor characteristics. Mean operative time was shorter in the MAC group (283.5 minutes vs. 313.3 minutes; P = 0.038). Hypertension was the most common intraoperative complication seen (8% in the MAC group vs. 9.7% in the AAA group; P = 0.794). Intraoperative seizure occurred at a rate of 4% in the MAC group and 3.2% in the AAA group (P = 0.858). Awake cases were converted to general anesthesia in no patients in the MAC group and in 1 patient (3.2%) in the AAA group (P = 0.201). No cases were aborted in either group. The mean hospital length of stay was 3.98 days in the MAC group and 3.84 days in the AAA group (P = 0.833). Both the MAC and AAA sedation techniques provide an efficacious and safe method for managing awake craniotomy cases and produce similar perioperative outcomes, with the MAC technique associated with shorter operative time. Copyright © 2017 Elsevier Inc. All rights reserved.

Electrocorticographic Frequency Alteration Mapping of Speech Cortex during an Awake Craniotomy: Case Report

PubMed Central

Breshears, J.; Sharma, M.; Anderson, N.R.; Rashid, S.; Leuthardt, E.C.

2010-01-01

Objective Traditional electrocortical stimulation (ECS) mapping is limited by the lengthy serial investigation (one location at a time) and the risk of afterdischarges in localizing eloquent cortex. Electrocorticographic frequency alteration mapping (EFAM) allows the parallel investigation of many cortical sites in much less time and with no risk of afterdischarges because of its passive nature. We examined its use with ECS in the context of language mapping during an awake craniotomy for a tumor resection. Clinical Presentation The patient was a 61-year-old right-handed Caucasian male who presented with headache and mild aphasia. Imaging demonstrated a 3-cm cystic mass in the posterior temporal-parietal lobe. The patient underwent an awake craniotomy for the mapping of his speech cortex and resection of the mass. Intervention Using a 32-contact electrode array, electrocorticographic signals were recorded from the exposed cortex as the patient participated in a 3-min screening task involving active (patient naming visually presented words) and rest (patient silent) conditions. A spectral comparison of the 2 conditions revealed specific cortical locations associated with activation during speech. The patient was then widely mapped using ECS. Three of 4 sites identified by ECS were also identified passively and in parallel by EFAM, 2 with statistical significance and the third by qualitative inspection. Conclusion EFAM was technically achieved in an awake craniotomy patient and had good concordance with ECS mapping. Because it poses no risk of afterdischarges and offers substantial time savings, EFAM holds promise for future development as an adjunct intraoperative mapping tool. Additionally, the cortical signals obtained by this modality can be utilized for localization in the presence of a tumor adjacent to the eloquent regions. PMID:19940544

“Awake” intraoperative functional MRI (ai-fMRI) for mapping the eloquent cortex: Is it possible in awake craniotomy?☆

PubMed Central

Lu, Jun-Feng; Zhang, Han; Wu, Jin-Song; Yao, Cheng-Jun; Zhuang, Dong-Xiao; Qiu, Tian-Ming; Jia, Wen-Bin; Mao, Ying; Zhou, Liang-Fu

2012-01-01

As a promising noninvasive imaging technique, functional MRI (fMRI) has been extensively adopted as a functional localization procedure for surgical planning. However, the information provided by preoperative fMRI (pre-fMRI) is hampered by the brain deformation that is secondary to surgical procedures. Therefore, intraoperative fMRI (i-fMRI) becomes a potential alternative that can compensate for brain shifts by updating the functional localization information during craniotomy. However, previous i-fMRI studies required that patients be under general anesthesia, preventing the wider application of such a technique as the patients cannot perform tasks unless they are awake. In this study, we propose a new technique that combines awake surgery and i-fMRI, named “awake” i-fMRI (ai-fMRI). We introduced ai-fMRI to the real-time localization of sensorimotor areas during awake craniotomy in seven patients. The results showed that ai-fMRI could successfully detect activations in the bilateral primary sensorimotor areas and supplementary motor areas for all patients, indicating the feasibility of this technique in eloquent area localization. The reliability of ai-fMRI was further validated using intraoperative stimulation mapping (ISM) in two of the seven patients. Comparisons between the pre-fMRI-derived localization result and the ai-fMRI derived result showed that the former was subject to a heavy brain shift and led to incorrect localization, while the latter solved that problem. Additionally, the approaches for the acquisition and processing of the ai-fMRI data were fully illustrated and described. Some practical issues on employing ai-fMRI in awake craniotomy were systemically discussed, and guidelines were provided. PMID:24179766

"Imagine your neighbor mows the lawn": a pilot study of psychological sequelae due to awake craniotomy: clinical article.

PubMed

Milian, Monika; Luerding, Ralf; Ploppa, Annette; Decker, Karlheinz; Psaras, Tsambika; Tatagiba, Marcos; Gharabaghi, Alireza; Feigl, Guenther C

2013-06-01

Although it has been reported that awake neurosurgical procedures are well tolerated, the long-term occurrence of general psychological sequelae has not yet been investigated. This study assessed the frequency and effects of psychological symptoms after an awake craniotomy on health-related quality of life (HRQOL). Sixteen patients undergoing an awake surgery were surveyed with a self-developed questionnaire, the Posttraumatic Stress Disorder Inventory For Awake Surgery Patients, which adopts the core components of the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) posttraumatic stress disorder (PTSD) criteria. The mean time between surgery and data collection was 97.3 ± 93.2 weeks. Health-related quality of life was assessed with the 36-Item Short Form Health Survey. Forty-four percent of the patients stated that they had experienced either repetitive distressing recollections or dreams related to the awake surgery, 18.8% stated persistent avoidance of stimuli associated with the awake surgery, and symptoms of increased arousal occurred in 62.5%. Two patients presented with postoperative psychological sequelae resembling PTSD symptoms. Younger age at surgery and female sex were risk factors for symptoms of increased arousal. The experience of intense anxiety during awake surgery appears to favor the development of postsurgical PTSD symptoms, while recurrent distressing recollections particularly affect HRQOL negatively. In many cases awake craniotomy is necessary to preserve language and motor function. However, in some cases awake craniotomy can lead to postoperative psychological sequelae resembling PTSD symptoms. Therefore, possible long-term effects of an awake surgery should be considered and discussed with the patient when planning this type of surgery.

Awake Craniotomy vs Craniotomy Under General Anesthesia for Perirolandic Gliomas: Evaluating Perioperative Complications and Extent of Resection.

PubMed

Eseonu, Chikezie I; Rincon-Torroella, Jordina; ReFaey, Karim; Lee, Young M; Nangiana, Jasvinder; Vivas-Buitrago, Tito; Quiñones-Hinojosa, Alfredo

2017-09-01

A craniotomy with direct cortical/subcortical stimulation either awake or under general anesthesia (GA) present 2 approaches for removing eloquent region tumors. With a reported higher prevalence of intraoperative seizures occurring during awake resections of perirolandic lesions, oftentimes, surgery under GA is chosen for these lesions. To evaluate a single-surgeon's experience with awake craniotomies (AC) vs surgery under GA for resecting perirolandic, eloquent, motor-region gliomas. Between 2005 and 2015, a retrospective analysis of 27 patients with perirolandic, eloquent, motor-area gliomas that underwent an AC were case-control matched with 31 patients who underwent surgery under GA for gliomas in the same location. All patients underwent direct brain stimulation with neuromonitoring and perioperative risk factors, extent of resection, complications, and discharge status were assessed. The postoperative Karnofsky Performance Score (KPS) was significantly lower for the GA patients at 81.1 compared to the AC patients at 93.3 ( P = .040). The extent of resection for GA patients was 79.6% while the AC patients had an 86.3% resection ( P = .136). There were significantly more 100% total resections in the AC patients 25.9% compared to the GA group (6.5%; P = .041). Patients in the GA group had a longer mean length of hospitalization of 7.9 days compared to the AC group at 4.2 days ( P = .049). We show that AC can be performed with more frequent total resections, better postoperative KPS, shorter hospitalizations, as well as similar perioperative complication rates compared to surgery under GA for perirolandic, eloquent motor-region glioma. Copyright © 2017 by the Congress of Neurological Surgeons

A pilot microdialysis study in brain tumor patients to assess changes in intracerebral cytokine levels after craniotomy and in response to treatment with a targeted anti-cancer agent.

PubMed

Portnow, Jana; Badie, Behnam; Liu, Xueli; Frankel, Paul; Mi, Shu; Chen, Mike; Synold, Timothy W

2014-05-01

Intracerebral microdialysis enables continuous measurement of changes in brain biochemistry. In this study intracerebral microdialysis was used to assess changes in cytokine levels after tumor resection and in response to treatment with temsirolimus. Brain tumor patients undergoing craniotomy participated in this non-therapeutic study. A 100 kDa molecular weight cut-off microdialysis catheter was placed in peritumoral tissue at the time of resection. Cohort 1 underwent craniotomy only. Cohort 2 received a 200 mg dose of intravenous temsirolimus 48 h after surgery. Dialysate samples were collected continuously for 96 h and analyzed for the presence of 30 cytokines. Serial blood samples were collected to measure systemic cytokine levels. Dialysate samples were obtained from six patients in cohort 1 and 4 in cohort 2. Seventeen cytokines could be recovered in dialysate samples from at least 8 of 10 patients. Concentrations of interleukins and chemokines were markedly elevated in peritumoral tissue, and most declined over time, with IL-8, IP-10, MCP-1, MIP1β, IL-6, IL-12p40/p70, MIP1α, IFN-α, G-CSF, IL-2R, and vascular endothelial growth factor significantly (p < 0.05) decreasing over 96 h following surgery. No qualitative changes in intracerebral or serum cytokine concentrations were detected after temsirolimus administration. This is the first intracerebral microdialysis study to evaluate the time course of changes in macromolecule levels in the peritumoral microenvironment after a debulking craniotomy. Initial elevations of peritumoral interleukins and chemokines most likely reflected an inflammatory response to both tumor and surgical trauma. These findings have implications for development of cellular therapies that are administered intracranially at the time of surgery.

Population Pharmacokinetics of Phenytoin Based on NONMEM in Patients with Intracranial Tumor During the First Week of Post-Craniotomy.

PubMed

Li, Zhong-Dong; Liu, Meng; Li, Liang; Wan, Jing-Hai; Lei, Zhaojin; Huang, Yong-An

2016-01-01

It was reported that phenytoin can prevent early post traumatic seizures. The present study aims to establish a population pharmacokinetic (PPK) model of oral phenytoin in patients with intracranial tumor during the early periods, the first week, of post-craniotomy to optimize phenytoin dosage regimen. Sixty-two patients with intracranial tumor were genotyped for CYP2C9 and CYP2C19 by real time PCR (TaqMan probe), and subsequently their phenytoin dosage regimens were designed according to the results of previous literature. A total of 123 plasma concentrations of oral phenytoin during the early periods of post-craniotomy, patient demographics, clinical biochemical indicators and drug combination were collected. A PPK model was performed using the nonlinear mixed effects model (NONMEM) program. The final PPK model equations of oral phenytoin were found to be as follows: for patients with CYP2C9 *1/*1, Vmax=22.66.(BWT/60.96)0.454(mg/h) and Km; =4.03 (mg/L); for patients with CYP2C9*1/*3, Vmax = 16.65.(BWT / 60.96 )0.454(mg/h) and Km =5.96 (mg/L). The PPK model was proved to be stable and effective by bootstrap method. Clinical individualized dosage regimens of additional 50 patients were designed by above PPK model. Concentrations on the morning of Day 7 (D7 concentrations) of 56% (28/50) of these patients were within the therapeutic range (10.20mg/L), which demonstrated better improvement than that of 37.1% of above 62 patients. The final PPK model of oral phenytoin may be helpful to design phenytoin individualized dosage regimen at the early stage of post-craniotomy when characteristics of patients meet these of subpopulation in the study.

Continuous physical examination during subcortical resection in awake craniotomy patients: Its usefulness and surgical outcome.

PubMed

Bunyaratavej, Krishnapundha; Sangtongjaraskul, Sunisa; Lerdsirisopon, Surunchana; Tuchinda, Lawan

2016-08-01

To evaluate the value of physical examination as a monitoring tool during subcortical resection in awake craniotomy patients and surgical outcomes. Authors reviewed medical records of patients underwent awake craniotomy with continuous physical examination for pathology adjacent to the eloquent area. Between January 2006 and August 2015, there were 37 patients underwent awake craniotomy with continuous physical examination. Pathology was located in the left cerebral hemisphere in 28 patients (75.7%). Thirty patients (81.1%) had neuroepithelial tumors. Degree of resections were defined as total, subtotal, and partial in 16 (43.2%), 11 (29.7%) and 10 (27.0%) patients, respectively. Median follow up duration was 14 months. The reasons for termination of subcortical resection were divided into 3 groups as follows: 1) by anatomical landmark with the aid of neuronavigation in 20 patients (54%), 2) by reaching subcortical stimulation threshold in 8 patients (21.6%), and 3) by abnormal physical examination in 9 patients (24.3%). Among these 3 groups, there were statistically significant differences in the intraoperative (p=0.002) and early postoperative neurological deficit (p=0.005) with the lowest deficit in neuronavigation group. However, there were no differences in neurological outcome at later follow up (3-months p=0.103; 6-months p=0.285). There were no differences in the degree of resection among the groups. Continuous physical examination has shown to be of value as an additional layer of monitoring of subcortical white matter during resection and combining several methods may help increase the efficacy of mapping and monitoring of subcortical functions. Copyright © 2016 Elsevier B.V. All rights reserved.

Thermally actuated wedge block

DOEpatents

Queen, Jr., Charles C.

1980-01-01

This invention relates to an automatically-operating wedge block for maintaining intimate structural contact over wide temperature ranges, including cryogenic use. The wedging action depends on the relative thermal expansion of two materials having very different coefficients of thermal expansion. The wedge block expands in thickness when cooled to cryogenic temperatures and contracts in thickness when returned to room temperature.

Temporal, thermal, and light stability of continuously tunable cholesteric liquid crystal laser array.

PubMed

Jeong, Mi-Yun; Chung, Ki Soo; Wu, Jeong Weon

2014-11-01

Fine-structured polymerized cholesteric liquid crystal (PCLC) wedge laser devices have been realized, with high fine spatial tunability of the lasing wavelength. With resolution less than 0.3 nm in a broad spectral range, more than one hundred laser lines could be obtained in a PCLC cell without extra devices. For practical device application, we studied the stability of the device in detail over time, and in response to strong external light sources, and thermal perturbation. The PCLC wedge cells had good temporal stability for 1 year and showed good stability for strong perturbations, with the lasing wavelength shifting less than 1 nm, while the laser peak intensities decreased by up to 34%, and the high energy band edge of the photonic band gap (PBG) was red shifted 3 nm by temperature perturbation. However, when we consider the entire lasing spectrum for the PCLC cell, the 1-nm wavelength shift may not matter. Although the laser peak intensities were decreased by up to 34% in total for all of the perturbation cases, the remaining 34% laser peak intensity is considerable extent to make use. This good stability of the PCLC laser device is due to the polymerization of the CLC by UV curing. This study will be helpful for practical CLC laser device development.

Late Holocene ice wedges near Fairbanks, Alaska, USA: Environmental setting and history of growth

USGS Publications Warehouse

Hamilton, T.D.; Ager, T.A.; Robinson, S.W.

1983-01-01

Test trenches excavated into muskeg near Fairbanks in 1969 exposed a polygonal network of active ice wedges. The wedges occur in peat that has accumulated since about 3500 yr BP and have grown episodically as the permafrost table fluctuated in response to fires, other local site conditions and perhaps regional climatic changes. Radiocarbon dates suggest one or two episodes of ice-wedge growth between about 3500 and 2000 yr BP as woody peat accumulated at the site. Subsequent wedge truncation evidently followed a fire that charred the peat. Younger peat exhibits facies changes between sedge-rich components that filled troughs over the ice wedges and woody bryophytic deposits that formed beyond the troughs. A final episode of wedge development took place within the past few hundred years. Pollen data from the site indicate that boreal forest was present throughout the past 6000 yr, but that it underwent a gradual transition from a predominantly deciduous to a spruce-dominated assemblage. This change may reflect either local site conditions or a more general climatic shift to cooler, moister summers in late Holocene time. The history of ice-wedge growth shows that wedges can form and grow to more than 1 m apparent width under mean annual temperatures that probably are close to those of the Fairbanks area today (-3.5°C) and under vegetation cover similar to that of the interior Alaskan boreal forest. The commonly held belief that ice wedges develop only below mean annual air temperatures of -6 to -8°C in the zone of continuous permafrost is invalid.

[Spectral Study on the Effects of Angle-Tuned Filter Wedge Angle Parameter to Reflecting Characteristics].

PubMed

Yu, Kan; Huang, De-xiu; Yin, Juan-juan; Bao, Jia-qi

2015-08-01

Three-port tunable optical filter is a key device in the all-optic intelligent switching network and dense wavelength division multiplexing system. The characteristics of the reflecting spectrum, especially the reflectivity and the isolation degree are very important to the three-port filter. Angle-tuned thin film filter is widely used as a three-port tunable filter for its high rectangular degree and good temperature stability. The characteristics of the reflecting spectrum are greatly influenced not only by the incident angle, but also by the wedge angle parameter of the non-paralleled wedge thin film filter. In the present paper, the influences of the wedge angle parameter to the reflectivity and the half bandwidth are analyzed, and the reflecting spectrum characterstics are simulationed in different wedge angle parameter and polarity. The wedge angle-tuned thin film filter with 0.8° wedge angle parameter is fabricated. The experimental results show that keeping the wedge angle the same orientation to the incident angle will worsen the reflectivity and the rectangular degree of the reflecting spectrum. However, keeping the wedge angle orientation reverse to the incident angle will enhance the reflectivity and decrease the bandwidth, which will give higher reflectivity and isolation degree to the three-port filter than that of high parallel degree angle-tuned thin film filter.

Numerical study on dusty shock reflection over a double wedge

NASA Astrophysics Data System (ADS)

Yin, Jingyue; Ding, Juchun; Luo, Xisheng

2018-01-01

The dusty shock reflection over a double wedge with different length scales is systematically studied using an adaptive multi-phase solver. The non-equilibrium effect caused by the particle relaxation is found to significantly influence the shock reflection process. Specifically, it behaves differently for double wedges with different length scales of the first wedge L1. For a double wedge with L1 relatively longer than the particle relaxation length λ, the equilibrium shock dominates the shock reflection and seven typical reflection processes are obtained, which is similar to the pure gas counterpart. For a double wedge with L1 shorter than λ, the non-equilibrium effect manifests more evidently, i.e., three parts of the dusty shock system including the frozen shock, the relaxation zone, and the equilibrium shock together dominate the reflection process. As a result, the shock reflection is far more complicated than the pure gas counterpart and eleven transition processes are found under various wedge angles. These findings give a complete description of all possible processes of dusty shock reflection over a double wedge and may be useful for better understanding the non-equilibrium shock reflection over complex structures.

A Case Report of Onyx Pulmonary Arterial Embolism Contributing to Hypoxemia During Awake Craniotomy for Arteriovenous Malformation Resection.

PubMed

Tolly, Brian T; Kosky, Jenna L; Koht, Antoun; Hemmer, Laura B

2017-02-15

A healthy 26-year-old man with cerebral arteriovenous malformation underwent staged endovascular embolization with Onyx followed by awake craniotomy for resection. The perioperative course was complicated by tachycardia and severe intraoperative hypoxemia requiring significant oxygen supplementation. Postoperative chest computed tomography (CT) revealed hyperattenuating Onyx embolization material within the pulmonary vasculature, and an electrocardiogram indicated possible right heart strain, supporting clinically significant embolism. With awake arteriovenous malformation resection following adjunctive Onyx embolization becoming increasingly employed for lesions involving the eloquent cortex, anesthesiologists need to be aware of pulmonary migration of Onyx material as a potential contributor to significant perioperative hypoxemia.

Anaesthetic Management of Supratentorial Tumor Craniotomy Using Awake-Throughout Approach.

PubMed

Shafiq, Faraz; Salim, Fahad; Enam, Ather; Parkash, Jai; Faheem, Mohammad

2017-12-01

The authors are reporting an anaesthetic management of patient presenting with left parietal lobe space occupying lesion and scheduled for Awake-craniotomy. Awake-throughout approach using scalp block was planned. Among techniques reported for keeping patient awake during the surgery, this one is really underutilized. The successful conduct requires thorough preoperative assessment and psychological preparation. We used powerpoint presentation as a preoperative teaching tool. The anatomical landmark technique was used to institute scalp block, where individual nerves were targeted bilaterally. Patient remained stable throughout and participated actively in intraoperative neurological monitoring. Postoperative period showed remarkable recovery, better pain control, and shorter length of stay in hospital.

Awake craniotomy for brain tumor: indications, technique and benefits.

PubMed

Dziedzic, Tomasz; Bernstein, Mark

2014-12-01

Increasing interest in the quality of life of patients after treatment of brain tumors has led to the exploration of methods that can improve intraoperative assessment of neurological status to avoid neurological deficits. The only method that can provide assessment of all eloquent areas of cerebral cortex and white matter is brain mapping during awake craniotomy. This method helps ensure that the quality of life and the neuro-oncological result of treatment are not compromised. Apart from the medical aspects of awake surgery, its economic issues are also favorable. Here, we review the main aspects of awake brain tumor surgery. Neurosurgical, neuropsychological, neurophysiological and anesthetic issues are briefly discussed.

Dexmedetomidine and Mannitol for Awake Craniotomy in a Pregnant Patient.

PubMed

Handlogten, Kathryn S; Sharpe, Emily E; Brost, Brian C; Parney, Ian F; Pasternak, Jeffrey J

2015-05-01

We describe the use of dexmedetomidine for an awake neurosurgical procedure in a pregnant patient and quantify the effect of mannitol on intrauterine volume. A 27-year-old woman underwent a craniotomy, with intraprocedural motor and speech mapping, at 20 weeks of gestation. Sedation was maintained with dexmedetomidine. Mannitol at 0.25 g/kg IV was administered to control brain volume during surgery. Internal uterine volume was estimated at 1092 cm before surgery and decreased to 770 and 953 cm at 9 and 48 hours, respectively, after baseline assessment. No adverse maternal or fetal effects were noted during the intraoperative period or up to 48 hours postoperatively.

Investigating bone chip formation in craniotomy.

PubMed

Huiyu, He; Chengyong, Wang; Yue, Zhang; Yanbin, Zheng; Linlin, Xu; Guoneng, Xie; Danna, Zhao; Bin, Chen; Haoan, Chen

2017-10-01

In a craniotomy, the milling cutter is one of the most important cutting tools. The operating performance, tool durability and cutting damage to patients are influenced by the tool's sharpness, intensity and structure, whereas the cutting characteristics rely on interactions between the tool and the skull. In this study, an orthogonal cutting experiment during a craniotomy of fresh pig skulls was performed to investigate chip formation on the side cutting and face cutting of the skull using a high-speed camera. The cutting forces with different combinations of cutting parameters, such as the rake angle, clearance angle, depth of cut and cutting speed, were measured. The skull bone microstructure and cutting damage were observed by scanning electron microscope. Cutting models for different cutting approaches and various depths of cut were constructed and analyzed. The study demonstrated that the effects of shearing, tension and extrusion occur during chip formation. Various chip types, such as unit chips, splintering chips and continuous chips, were generated. Continuous pieces of chips, which are advisable for easy removal from the field of operation, were formed at greater depths of cut and tool rake angles greater than 10°. Cutting damage could be relieved with a faster recovery with clearance angles greater than 20°.

Surgical and anesthesiological considerations of awake craniotomy: Cerrahpasa experience.

PubMed

Sanus, Galip Zihni; Yuksel, Odhan; Tunali, Yusuf; Ozkara, Cigdem; Yeni, Naz; Ozlen, Fatma; Tanriverdi, Taner; Ozyurt, Emin; Uzan, Mustafa

2015-01-01

Awake craniotomy (AC) with electrical cortical stimulation has become popular during the last ten years although the basic principles were introduced almost 50 years ago. The aim of this paper is to share with the readers our experience in 25 patients who underwent AC with electrical stimulation. Twenty-five patients who underwent AC between 2010 and 2013 are the subjects of this paper. All patients were diagnosed with intraaxial lesions involving the functional area itself or very close to it by preoperative imaging. During surgery, the functional area was demonstrated by cortical electrical stimulation and resection aimed to preserve it in order to avoid an irreversible functional deficit. Total resection was possible in 80% while in 20% subtotal resection had to be performed because of involvement of the functional area itself. The neurological complication rate was found to be 16% (4 patients) and all were transient. No complication regarding anesthesia was noted. Awake craniotomy in selected patients is very effective, safe and practical for supratentorial lesions close to the eloquent area. Complications related to the surgery itself are uncommon and general anesthesia is avoided. The hospital stay including the intensive care unit is short which makes it very economical surgical procedure.

Herpes Simplex Type 2 Encephalitis After Craniotomy: Case Report and Literature Review.

PubMed

Berger, Assaf; Shahar, Tal; Margalit, Nevo

2016-04-01

Herpes simplex encephalitis (HSE) after neurosurgical procedures is extremely uncommon, and the few published case reports mainly described herpes simplex virus type 1 (HSV-1) as being culpable. We present a rare case of HSV-2 encephalitis after craniotomy and describe its pathophysiology and optimal management. A 70-year-old woman underwent an elective resection of a recurrent left sphenoid wing meningioma and clipping of a left middle cerebral artery aneurysm, the latter having been found incidentally. She returned to our department with clinical findings suggestive of meningitis 12 days after the operation. Her lack of response to empiric antibiotic treatment, taken together with the lymphocyte-predominant initial cerebrospinal fluid obtained by lumbar puncture and the electroencephalographic indications of encephalopathy, led to the suspicion of a diagnosis of HSE, which was later confirmed by a polymerase chain reaction test positive for HSV-2. The patient was then successfully treated with intravenous acyclovir for 2 weeks followed by another week of oral acyclovir treatment before being discharged. The present case stresses the importance of recognizing the relatively rare entity of HSE after craniotomy. Timely correct diagnosis will expedite the initiation of appropriate treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

da Vinci robot-assisted keyhole neurosurgery: a cadaver study on feasibility and safety.

PubMed

Marcus, Hani J; Hughes-Hallett, Archie; Cundy, Thomas P; Yang, Guang-Zhong; Darzi, Ara; Nandi, Dipankar

2015-04-01

The goal of this cadaver study was to evaluate the feasibility and safety of da Vinci robot-assisted keyhole neurosurgery. Several keyhole craniotomies were fashioned including supraorbital subfrontal, retrosigmoid and supracerebellar infratentorial. In each case, a simple durotomy was performed, and the flap was retracted. The da Vinci surgical system was then used to perform arachnoid dissection towards the deep-seated intracranial cisterns. It was not possible to simultaneously pass the 12-mm endoscope and instruments through the keyhole craniotomy in any of the approaches performed, limiting visualization. The articulated instruments provided greater dexterity than existing tools, but the instrument arms could not be placed in parallel through the keyhole craniotomy and, therefore, could not be advanced to the deep cisterns without significant clashing. The da Vinci console offered considerable ergonomic advantages over the existing operating room arrangement, allowing the operating surgeon to remain non-sterile and seated comfortably throughout the procedure. However, the lack of haptic feedback was a notable limitation. In conclusion, while robotic platforms have the potential to greatly enhance the performance of transcranial approaches, there is strong justification for research into next-generation robots, better suited to keyhole neurosurgery.

Acoustic field of a wedge-shaped section of a spherical cap transducer

NASA Astrophysics Data System (ADS)

Ketterling, Jeffrey A.

2003-12-01

The acoustic pressure field at an arbitrary point in space is derived for a wedge-shaped section of a spherical cap transducer using the spatial impulse response (SIR) method. For a spherical surface centered at the origin, a wedge shape is created by taking cuts in the X-Y and X-Z planes and removing the smallest surface component. Analytic expressions are derived for the SIR based on spatial location. The expressions utilize the SIR solutions for a spherical cap transducer [Arditi et al., Ultrason. Imaging 3, 37-61 (1981)] with additional terms added to account for the reduced surface area of the wedge. Results from the numerical model are compared to experimental measurements from a wedge transducer with an 8-cm outer diameter and 9-cm geometric focus. The experimental and theoretical -3-dB beamwidths agreed to within 10%+/-5%. The SIR model for a wedge-shaped transducer is easily extended to other spherically curved transducer geometries that consist of combinations of wedge sections and spherical caps.

Acoustic field of a wedge-shaped section of a spherical cap transducer.

PubMed

Ketterling, Jeffrey A

2003-12-01

The acoustic pressure field at an arbitrary point in space is derived for a wedge-shaped section of a spherical cap transducer using the spatial impulse response (SIR) method. For a spherical surface centered at the origin, a wedge shape is created by taking cuts in the X-Y and X-Z planes and removing the smallest surface component. Analytic expressions are derived for the SIR based on spatial location. The expressions utilize the SIR solutions for a spherical cap transducer [Arditi et al., Ultrason. Imaging 3, 37-61 (1981)] with additional terms added to account for the reduced surface area of the wedge. Results from the numerical model are compared to experimental measurements from a wedge transducer with an 8-cm outer diameter and 9-cm geometric focus. The experimental and theoretical -3-dB beamwidths agreed to within 10% +/- 5%. The SIR model for a wedge-shaped transducer is easily extended to other spherically curved transducer geometries that consist of combinations of wedge sections and spherical caps.

The Cosmonaut Sea Wedge

USGS Publications Warehouse

Solli, K.; Kuvaas, B.; Kristoffersen, Y.; Leitchenkov, G.; Guseva, J.; Gandyukhin, V.

2007-01-01

A set of multi-channel seismic profiles (~15000 km) acquired by Russia, Norway and Australia has been used to investigate the depositional evolution of the Cosmonaut Sea margin of East Antarctica. We recognize a regional sediment wedge below the upper part of the continental rise. The wedge, herein termed the Cosmonaut Sea Wedge, is positioned stratigraphically underneath the inferred glaciomarine section and extends for at least 1200 km along the continental margin and from 80 to about 250 km seaward or to the north. Lateral variations in the growth pattern of the wedge indicate several overlapping depocentres, which at their distal northern end are flanked by elongated mounded drifts and contourite sheets. The internal stratification of the mounded drift deposits suggests that westward flowing bottom currents reworked the marginal deposits. The action of these currents together with sea-level changes is considered to have controlled the growth of the wedge. We interpret the Cosmonaut Sea Wedge as a composite feature comprising several bottom current reworked fan systems.

Periodic nanostructures from self assembled wedge-type block-copolymers

DOEpatents

Xia, Yan; Sveinbjornsson, Benjamin R.; Grubbs, Robert H.; Weitekamp, Raymond; Miyake, Garret M.; Piunova, Victoria; Daeffler, Christopher Scot

2015-06-02

The invention provides a class of wedge-type block copolymers having a plurality of chemically different blocks, at least a portion of which incorporates a wedge group-containing block providing useful properties. For example, use of one or more wedge group-containing blocks in some block copolymers of the invention significantly inhibits chain entanglement and, thus, the present block copolymers materials provide a class of polymer materials capable of efficient molecular self-assembly to generate a range of structures, such as periodic nanostructures and microstructures. Materials of the present invention include copolymers having one or more wedge group-containing blocks, and optionally for some applications copolymers also incorporating one or more polymer side group-containing blocks. The present invention also provides useful methods of making and using wedge-type block copolymers.

Contact and crack problems for an elastic wedge. [stress concentration in elastic half spaces

NASA Technical Reports Server (NTRS)

Erdogan, F.; Gupta, G. D.

1974-01-01

The contact and the crack problems for an elastic wedge of arbitrary angle are considered. The problem is reduced to a singular integral equation which, in the general case, may have a generalized Cauchy kernel. The singularities under the stamp as well as at the wedge apex were studied, and the relevant stress intensity factors are defined. The problem was solved for various wedge geometries and loading conditions. The results may be applicable to certain foundation problems and to crack problems in symmetrically loaded wedges in which cracks initiate from the apex.

Evaluation of Landsat-7 SLC-off image products for forest change detection

USGS Publications Warehouse

Wulder, Michael A.; Ortlepp, Stephanie M.; White, Joanne C.; Maxwell, Susan

2008-01-01

Since July 2003, Landsat-7 ETM+ has been operating without the scan line corrector (SLC), which compensates for the forward motion of the satellite in the imagery acquired. Data collected in SLC-off mode have gaps in a systematic wedge-shaped pattern outside of the central 22 km swath of the imagery; however, the spatial and spectral quality of the remaining portions of the imagery are not diminished. To explore the continued use of Landsat-7 ETM+ SLC-off imagery to characterize change in forested environments, we compare the change detection results generated from a reference image pair (a 1999 Landsat-7 ETM+ image and a 2003 Landsat-5 TM image) with change detection results generated from the same 1999 Landsat-7 ETM+ image coupled with three different 2003 Landsat-7 SLC-off products: unremediated SLC-off (i.e., with gaps); histogram-based gap-filled; and segment-based gap-filled. The results are compared on both a pixel and polygon basis; on a pixel basis, the unremediated SLC-off product missed 35% of the change identified by the reference data, and the histogram- and segment-based gap-filled products missed 23% and 21% of the change, respectively. When using forest inventory polygons as a context for change (to reduce commission error), the amount of change missed was 31%, 14%, and 12% for the each of the unremediated, histogram-based gap-filled, and segment-based gap-filled products, respectively. Our results indicate that over the time period considered, and given the types and spatial distribution of change events within our study area, the gap-filled products can provide a useful data source for change detection in forested environments. The selection of which product to use is, however, very dependent on the nature of the application and the spatial configuration of change events. ?? 2008 Government of Canada.

Minimum work analysis on the critical taper accretionary wedges- insights from analogue modeling

NASA Astrophysics Data System (ADS)

Santimano, Tasca; Rosenau, Matthias; Oncken, Onno

2014-05-01

The Critical taper theory (CTT) is a fundamental concept for the understanding of mountain building processes. Based on force balance it predicts the preferred steady state geometry of an accretionary wedge system and its tectonic regime (extensive, compressive, stable). However, it does not specify which structures are formed and reactivated to reach the preferred state. The latter can be predicted by the minimum work concept. Here we test both concepts and their interplay by analysing two simple sand wedge models which differ only in the thickness of the basal detachment (a layer of glass beads). While the steady state critical taper is controlled by internal and basal friction coefficients and therefore the same in all experiments, different processes can minimise work by 1. reducing gravitational work e.g. by lowering the amount of uplift or volume uplifted, or 2. reducing frictional work e.g. by lowering the load or due to low friction coefficient along thrusts. Since a thick detachment allows entrainment of low friction material and therefore lowering of the friction along active thrusts, we speculate that the style of wedge growth will differ between the two models. We observe that the wedge with a thin basal detachment localizes strain at the toe of the wedge periodically and reactivate older faults to reach the critical topography. On the contrary, in the wedge with the thicker detachment layer, friction along thrusts is lowered due to the entrainment of low friction material from the detachment zone, subsequently increasing the lifetime of a thrust. Long thrust episodes are always followed by a fault of shorter lifetime, with the aim of reaching the critical taper. From the two experiments, we analyze the time-series evolution of the wedge to infer the work done by the two styles of deformation and predict the trend over time to differ but the maximum work to be similar Our observations show that the critical taper theory determines the geometry of the wedge in particular the taper angle. However the path and style of deformation that the wedge adopts i.e. strain partitioning or deformation along one fault, is determined by the energetically lowest pathway. The observation is especially evident in wedges with added complexities or random changes as the wedge matures. This study combines two theories to explain variability in the results of analogue models and perhaps may aid in understanding the complexity in natural wedges. It also delineates that two different mechanics of deformation can lead to the same geometrical wedge or final topography.

Ancient Yedoma carbon loss: primed by ice wedge thaw?

NASA Astrophysics Data System (ADS)

Dowdy, K. L.; Vonk, J. E.; Mann, P. J.; Zimov, N.; Bulygina, E. B.; Davydova, A.; Spencer, R. G.; Holmes, R. M.

2012-12-01

Northeast Siberian permafrost is dominated by frozen Yedoma deposits containing ca. 500 Gt of carbon, nearly a quarter of northern permafrost organic carbon (OC). Yedoma deposits are Pleistocene-age alluvial and/or aeolian accumulations characterized by high ice wedge content (~50%), making them particularly vulnerable to a warming climate and to surface collapse upon thaw. Dissolved OC in streams originating primarily from Yedoma has been shown to be highly biolabile, relative to waters containing more modern OC. The cause of this biolability, however, remains speculative. Here we investigate the influence of ice wedge input upon the bioavailability of Yedoma within streams from as a potential cause of Yedoma carbon biolability upon release into the Kolyma River from the thaw-eroding river exposures of Duvannyi Yar, NE Siberia. We measured biolability on (1) ice wedge, Kolyma, and Yedoma leachate controls; (2) ice wedge and Kolyma plus Yedoma OC (8 g/L); and (3) varying ratios of ice wedge water to Kolyma river water. Biolability assays were conducted using both 5-day BOD (biological oxygen demand) and 11-day BDOC (biodegradable dissolved organic carbon) incubations. We found that ancient DOC in Yedoma soil leachate alone was highly biolabile with losses of 52±0.1% C over a 5-day BOD incubation. Similarly, DOC contained in pure ice wedge water was found to be biolabile, losing 21±0% C during a 5-day BOD incubation. Increased ice wedge contributions led to higher overall C losses in identical Yedoma soil leachates, with 8.9±0.6% losses of Yedoma C with 100% ice wedge water, 7.1±1% (50% ice wedge/ 50% Kolyma) and 5±0.3% with 100% Kolyma River water. We discuss potential mechanisms for the increased loss of ancient C using associated measurements of nutrient availability, carbon quality (CDOM/FDOM) and extracellular enzyme activity rates. Our initial results indicate that ice wedge meltwater forming Yedoma streams makes Yedoma OC more bioavailable than it would be if mixed with Kolyma River water alone, suggesting that leach water origin acts as a control on the turnover of old C. The higher reactivity of Yedoma OC in ice wedge meltwater compared to Kolyma River water suggests that further ice wedge and permafrost thaw in Yedoma deposits will likely result in increased CO2 flux into the atmosphere.

3D seismic investigation of the structural and stratigraphic characteristics of the Pagasa Wedge, Southwest Palawan Basin, Philippines, and their tectonic implications

NASA Astrophysics Data System (ADS)

Ilao, Kimberly A.; Morley, Christopher K.; Aurelio, Mario A.

2018-04-01

The Pagasa Wedge is a poorly imaged deepwater orogenic wedge that has been variously interpreted as representing an accretionary prism, a former accretionary prism modified by thrusting onto a thinned continental margin, and a gravity-driven fold-thrust belt. This study, using 2D and 3D seismic data, together with well information indicates that at least the external part of the wedge is dominantly composed of mass transport complexes, capped by syn-kinematic sediments that have thrusts and normal faults superimposed upon them. Drilling shows that despite stratigraphic repetition of Eocene Middle Miocene units, there is stratigraphic omission of Oligocene and Early Miocene units. This absence suggests that mass transport processes have introduced the Eocene section into the wedge rather than tectonic thrusting. The accretionary prism stage (Oligocene) of the Central Palawan Ophiolite history appears to be marked by predominantly north-vergent deformation. The Deep Regional Unconformity (∼17 Ma) likely indicates the approximate time when obduction ceased in Palawan. The Pagasa Wedge is a late-stage product of the convergence history that was active in its final phase sometime above the top of the Nido Limestone (∼16 Ma) and the base of the Tabon Limestone in the Aboabo-A1X well (∼9 Ma). The top of the wedge is traditionally associated with the Middle Miocene Unconformity (MMU), However the presence of multiple unconformities, diachronous formation tops, local tectonic unconformities and regional diachronous events (e.g. migrating forebulges) all suggest simply giving a single age (or assigning a single unconformity, such as the MMU as defining the top of the Pagasa Wedge is inappropriate. The overall NE-SW trend of the wedge, and the dominant NW transport of structures within the wedge diverge from the more northerly transport direction determined from outcrops in Palawan, and also from the Nido Limestone in the SW part of the Pagasa Wedge. Possibly this NW transport direction is more related to gravity-driven structures responding to uplift of NE-SW Dangerous Grounds margin during the Middle Miocene (related to slab breakoff?) than it is to thrusting rooted in a plate boundary. The final modification of the wedge occurred when the effects of compression deformation on the wedge had largely ended, but gravity processes (in particular mass transport and normal faulting) still operated.

Beyond the Playground: Sandboxes in the Classroom examine the Interplay of Mountain Building and Erosion

NASA Astrophysics Data System (ADS)

Cooke, M.; Ellsworth, M.; Del Castello, M.; Jakubowyc, K.

2006-05-01

The growth of accretionary wedges along subducting plate margins has inspired generations of sandbox experiments. These experiments typically contract sand layers to simulate the deformation of sedimentary rocks as the wedge grows in width and height. In the absence of erosional processes, the ratio of wedge height to width will remain constant during wedge growth. The growth is accommodated by the successive development of faults in front of the wedge. However, as erosion reduces the slope of the wedge or removes material from portions of the wedge, the internal deformation of the wedge changes and the faulting sequence is altered. Scientists at the University of Massachusetts are researching fault system development within accretionary systems using a work budget approach. Faults slip and grow in order to minimize the work against gravity, internal work and frictional heating due to slip along faults. High school Earth System teachers at the Model Secondary School for the Deaf in Washington, DC have performed sandbox experiments where students document and record the changes in accretionary wedge growth due to erosion. The sandbox was designed to simulate a variety of tectonic situations and to be suitable for use in the classroom. The wide dimensions of the sandbox permit comparison of different erosive patterns along the strike of the wedge. Students can observe and measure the growth of the wedge within side windows and within map view. The data recorded by students can be integrated with numerical models of the UMass scientists to show how erosion reduces work against gravity and frictional heating to facilitate faulting within the wedge. Collaboration between the high school students and geoscientists has been augmented by video-conferences and annual field trip workshops with other high schools for the deaf participating in the SOAR-high partnership. The 6 schools from around the United States involved with the SOAR-high learning community all use sandbox experiments within their earth system classrooms. The sandbox experiments provide a wonderful hands-on opportunity that invigorates learning about geologic deformation.

Ice Wedges as Winter Climate Archives - New Results from the Northeast Siberian Arctic and Discussion of the Paleoclimatic Value of Ice Wedges

NASA Astrophysics Data System (ADS)

Opel, T.; Meyer, H.; Laepple, T.; Rehfeld, K.; Mollenhauer, G.; Alexander, D.; Murton, J.

2017-12-01

Arctic climate has experienced major changes over the past millennia that are yet not fully understood in terms of external and internal controls, spatial, temporal, and seasonal patterns. The interpretation of stable isotope data in permafrost ice wedges provides unique information on past winter climate, not or not sufficiently captured by other Arctic climate archives. Ice wedges grow in polygonal patterns owing to frost cracking of the frozen ground in winter and frost-crack filling mostly by snowmelt in spring. Their oxygen isotope values are indicative of temperatures in the cold period of the year (meteorological winter and spring). Recently, an ice-wedge record from the Lena River Delta suggested for the first time, that Siberian winter temperatures were warming throughout the Holocene, contradicting most other Arctic paleoclimate reconstructions. As this was based on a single record, the representativity and spatial extent of the reconstructed winter warming signal remained unclear. In this two-part contribution, we first present a new ice-wedge δ18O record from the Oyogos Yar mainland coast (Northeast Siberian Arctic) and then discuss more generally the paleoclimatic value of ice wedges. The new Oyogos Yar ice-wedge record is based on paired stable-isotope and radiocarbon-age data and spans the last two millennia. It confirms the long-term winter warming signal as well as the unprecedented temperature rise in the last decades. This demonstrates that winter warming over the last millennia is a coherent feature in the Northeastern Siberian Arctic, supporting the hypothesis of an insolation-driven seasonal Holocene temperature evolution followed by a strong warming most likely related to anthropogenic forcing. Considering additional ice-wedge data from the Siberian Laptev Sea region we discuss the paleoclimatic value of ice wedges as high-quality winter climate archive. We assess potentials and challenges of this so far rather understudied source of paleoclimate information that remains to be evaluated systematically. In addition, we outline priorities for future ice-wedge research in order to fully exploit the potential of ice wedges for paleoclimate reconstruction, including e.g. better process understanding, dating, and data-model comparison.

A possible mechanism for earthquakes found in the mantle wedge of the Nazca subduction zone

NASA Astrophysics Data System (ADS)

Warren, L. M.; Chang, Y.; Prieto, G. A.

2017-12-01

Beneath Colombia, the Cauca cluster of intermediate-depth earthquakes extends for 200 km along the trench (3.5°N-5.5°N, 77.0°W-75.3°W) and, with 58 earthquakes per year with local magnitude ML >= 2.5, has a higher rate of seismicity than the subduction zone immediately to the north or south. By precisely locating 433 cluster earthquakes from 1/2010-3/2014 with data from the Colombian National Seismic Network, we found that the earthquakes are located both in a continuous Nazca plate subducting at an angle of 33°-43° and in the overlying mantle wedge. The mantle wedge earthquakes (12% of the earthquakes) form two isolated 40-km-tall columns extending perpendicular to the subducting slab. Using waveform inversion, we computed focal mechanisms for 69 of the larger earthquakes. The focal mechanisms are variable, but the intraslab earthquakes are generally consistent with an in-slab extensional stress axis oriented 25° counterclockwise from the down-dip direction. We suggest that the observed mantle wedge earthquakes are the result of hydrofracture in a relatively cool mantle wedge. This segment of the Nazca Plate is currently subducting at a normal angle, but Wagner et al. (2017) suggested that a flat slab slowly developed in the region between 9-5.9 Ma and persisted until 4 Ma. During flat slab subduction, the overlying mantle wedge typically cools because it is cut off from mantle corner flow. After hydrous minerals in the slab dehydrate, the dehydrated fluid is expelled from the slab and migrates through the mantle wedge. If a cool mantle wedge remains today, fluid dehydrated from the slab may generate earthquakes by hydrofracture, with the mantle wedge earthquakes representing fluid migration pathways. Dahm's (2000) model of water-filled fracture propagation in the mantle wedge shows hydrofractures propagating normal to the subducting slab and extending tens of km into the mantle wedge, as we observe.

Effect of Foot Progression Angle and Lateral Wedge Insole on a Reduction in Knee Adduction Moment.

PubMed

Tokunaga, Ken; Nakai, Yuki; Matsumoto, Ryo; Kiyama, Ryoji; Kawada, Masayuki; Ohwatashi, Akihiko; Fukudome, Kiyohiro; Ohshige, Tadasu; Maeda, Tetsuo

2016-10-01

This study evaluated the effect of foot progression angle on the reduction in knee adduction moment caused by a lateral wedged insole during walking. Twenty healthy, young volunteers walked 10 m at their comfortable velocity wearing a lateral wedged insole or control flat insole in 3 foot progression angle conditions: natural, toe-out, and toe-in. A 3-dimensional rigid link model was used to calculate the external knee adduction moment, the moment arm of ground reaction force to knee joint center, and the reduction ratio of knee adduction moment and moment arm. The result indicated that the toe-out condition and lateral wedged insole decreased the knee adduction moment in the whole stance phase. The reduction ratio of the knee adduction moment and the moment arm exhibited a close relationship. Lateral wedged insoles decreased the knee adduction moment in various foot progression angle conditions due to decrease of the moment arm of the ground reaction force. Moreover, the knee adduction moment during the toe-out gait with lateral wedged insole was the smallest due to the synergistic effect of the lateral wedged insole and foot progression angle. Lateral wedged insoles may be a valid intervention for patients with knee osteoarthritis regardless of the foot progression angle.

Effects of medially wedged foot orthoses on knee and hip joint running mechanics in females with and without patellofemoral pain syndrome.

PubMed

Boldt, Andrew R; Willson, John D; Barrios, Joaquin A; Kernozek, Thomas W

2013-02-01

We examined the effects of medially wedged foot orthoses on knee and hip joint mechanics during running in females with and without patellofemoral pain syndrome (PFPS). We also tested if these effects depend on standing calcaneal eversion angle. Twenty female runners with and without PFPS participated. Knee and hip joint transverse and frontal plane peak angle, excursion, and peak internal knee and hip abduction moment were calculated while running with and without a 6° full-length medially wedged foot orthoses. Separate 3-factor mixed ANOVAs (group [PFPS, control] x condition [medial wedge, no medial wedge] x standing calcaneal angle [everted, neutral, inverted]) were used to test the effect of medially wedged orthoses on each dependent variable. Knee abduction moment increased 3% (P = .03) and hip adduction excursion decreased 0.6° (P < .01) using medially wedged foot orthoses. No significant group x condition or calcaneal angle x condition effects were observed. The addition of medially wedged foot orthoses to standardized running shoes had minimal effect on knee and hip joint mechanics during running thought to be associated with the etiology or exacerbation of PFPS symptoms. These effects did not appear to depend on injury status or standing calcaneal posture.

Scattering of In-Plane Waves by Elastic Wedges

NASA Astrophysics Data System (ADS)

Mohammadi, K.; Asimaki, D.; Fradkin, L.

2014-12-01

The scattering of seismic waves by elastic wedges has been a topic of interest in seismology and geophysics for many decades. Analytical, semi-analytical, experimental and numerical studies on idealized wedges have provided insight into the seismic behavior of continental margins, mountain roots and crustal discontinuities. Published results, however, have almost exclusively focused on incident Rayleigh waves and out-of-plane body (SH) waves. Complementing the existing body of work, we here present results from our study on the res­ponse of elastic wedges to incident P or SV waves, an idealized pro­blem that can provide valuable insight to the understanding and parameterization of topographic ampli­fication of seismic ground mo­tion. We first show our earlier work on explicit finite difference simulations of SV-wave scattering by elastic wedges over a wide range of internal angles. We next present a semi-analytical solution that we developed using the approach proposed by Gautesen, to describe the scattered wavefield in the immediate vicinity of the wedge's tip (near-field). We use the semi-analytical solution to validate the numerical analyses, and improve resolution of the amplification factor at the wedge vertex that spikes when the internal wedge angle approaches the critical angle of incidence.

Stable isotope and gas properties of two ice wedges from Cape Mamontov Klyk, Laptev Sea, Northern Siberia

NASA Astrophysics Data System (ADS)

Boereboom, T.; Samyn, D.; Meyer, H.; Tison, J.-L.

2011-12-01

This paper presents and discusses the texture, fabric and gas properties (contents of total gas, O2, N2, CO2, and CH4) of two ice wedges from Cape Mamontov Klyk, Laptev Sea, Northern Siberia. The two ice wedges display contrasting structures: one being of relatively "clean" ice and the other showing clean ice at its centre as well as debris-rich ice on its sides (referred to as ice-sand wedge). A comparison of gas properties, crystal size, fabrics and stable isotope data (δ18O and δD) allows discriminating between three different facies of ice with specific paleoenvironmental signatures, suggesting different climatic conditions and rates of biological activity. More specifically, total gas content and composition reveal variable intensities of meltwater infiltration and show the impact of biological processes with contrasting contributions from anaerobic and aerobic conditions. Stable isotope data are shown to be valid for discussing changes in paleoenvironmental conditions and/or decipher different sources for the snow feeding into the ice wedges with time. Our data also give support to the previous assumption that the composite ice wedge was formed in Pleistocene and the ice wedge in Holocene times. This study sheds more light on the conditions of ice wedge growth under changing environmental conditions.

Are the new starting block facilities beneficial for backstroke start performance?

PubMed

de Jesus, Karla; de Jesus, Kelly; Abraldes, J Arturo; Medeiros, Alexandre Igor Araripe; Fernandes, Ricardo J; Vilas-Boas, João Paulo

2016-01-01

We aimed to analyse the handgrip positioning and the wedge effects on the backstroke start performance and technique. Ten swimmers completed randomly eight 15 m backstroke starts (four with hands on highest horizontal and four on vertical handgrip) performed with and without wedge. One surface and one underwater camera recorded kinematic data. Standardised mean difference (SMD) and 95% confidence intervals (CI) were used. Handgrip positioning did not affect kinematics with and without wedge use. Handgrips horizontally positioned and feet over wedge displayed greater knee angular velocity than without it (SMD = -0.82; 95% CI: -1.56, -0.08). Hands vertically positioned and feet over wedge presented greater take-off angle (SMD = -0.81; 95% CI: -1.55, -0.07), centre of mass (CM) vertical positioning at first water contact (SMD = -0.97; 95% CI: -1.87, -0.07) and CM vertical velocity at CM immersion (SMD = 1.03; 95% CI: 0.08, 1.98) when comparing without wedge use. Swimmers extended the hip previous to the knee and ankle joints, except for the variant with hands vertically positioned without wedge (SMD = 0.75; 95% CI: -0.03, 1.53). Swimmers should preserve biomechanical advantages achieved during flight with variant with hands vertically positioned and wedge throughout entry and underwater phase.

Rotation in a gravitational billiard

NASA Astrophysics Data System (ADS)

Peraza-Mues, G. G.; Carvente, Osvaldo; Moukarzel, Cristian F.

Gravitational billiards composed of a viscoelastic frictional disk bouncing on a vibrating wedge have been studied previously, but only from the point of view of their translational behavior. In this work, the average rotational velocity of the disk is studied under various circumstances. First, an experimental realization is briefly presented, which shows sustained rotation when the wedge is tilted. Next, this phenomenon is scrutinized in close detail using a precise numerical implementation of frictional forces. We show that the bouncing disk acquires a spontaneous rotational velocity whenever the wedge angle is not bisected by the direction of gravity. Our molecular dynamics (MD) results are well reproduced by event-driven (ED) simulations. When the wedge aperture angle θW>π/2, the average tangential velocity Rω¯ of the disk scales with the typical wedge vibration velocity vb, and is in general a nonmonotonic function of the overall tilt angle θT of the wedge. The present work focuses on wedges with θW=2π/3, which are relevant for the problem of spontaneous rotation in vibrated disk packings. This study makes part of the PhD Thesis of G. G. Peraza-Mues.

Sedimentary Fabrics of Stratified Slope Deposits at a Site near Hoover's Camp, Shenandoah National Park, Virginia

USGS Publications Warehouse

Smoot, Joseph P.

2004-01-01

An outcrop of stratified slope deposits in Shenandoah National Park is described in detail. The Pleistocene age deposits are comprised of a mixture of clay to cobbles defining a series of offlapping wedges. Elongate clasts are oriented parallel to wedge boundaries except at the toe of the wedge, where they are oriented nearly vertical. The wedges represent sedimentation by freeze-thaw of ground ice. Thin layers of pebbly sand separate matrix-rich wedge deposits, which represent sheetfloods during periods of thaw. Thicker sand layers and lenses of clay are placed upslope of coarse-grained wedge fronts. This association represents ponding of water around the solifluction lobe topography during warm periods. Stratified slope deposits at an outcrop at a higher elevation lack the sandy sheetflood and pond deposits, whereas sheetflood fabrics dominate deposits at a lower elevation. These variations are attributed to differences in temperature at the different elevations.

Mechanics of fold-and-thrust belts and accretionary wedges Cohesive Coulomb theory

NASA Technical Reports Server (NTRS)

Dahlen, F. A.; Suppe, J.; Davis, D.

1984-01-01

A self-consistent theory for the mechanics of thin-skinned accretionary Coulomb wedges is developed and applied to the active fold-and-thrust belt of western Taiwan. The state of stress everywhere within a critical wedge is determined by solving the static equilibrium equations subject to the appropriate boundary conditions. The influence of wedge cohesion, which gives rise to a concave curvature of the critical topographic surface and affects the orientation of the principal stresses and Coulomb fracture within the wedge, is considered. The shape of the topographic surface and the angles at which thrust faults step up from the basal decollement in the Taiwanese belt is analyzed taking into account the extensive structural and fluid-pressure data available there. It is concluded that the gross geometry and structure of the Taiwan wedge are consistent with normal laboratory frictional and fracture strengths of sedimentary rocks.

Cosmetic reconstruction of temporal defect following pterional [corrected] craniotomy.

PubMed

Badie, B

1996-04-01

Depression of the temporal fossa that is often caused by atrophy of the temporalis muscle or superficial temporal fat pad may be an unavoidable defect following pterional craniotomy. Various techniques have been previously described to correct this disfiguring defect. Most techniques, however, require drilling holes into the cranium or the synthetic grafts for attachment of the temporalis muscle. A simple method is described by which a temporal fossa depression is repaired with methylmethacrylate bone cement and a new superior temporal line is created for attachment of the temporalis muscle without the need to drill suture holes into the acrylic or the cranium. The technique described has been used on several patients with excellent cosmetic outcome.

The minimally invasive endoscopic management of septated chronic subdural hematomas: surgical technique.

PubMed

Berhouma, M; Jacquesson, T; Jouanneau, E

2014-12-01

Fibrin membranes and compartmentalization within the subdural space are a frequent cause of failure in the treatment of chronic subdural hematomas (CSH). This specific subtype of CSH classically requires craniotomy, which carries significant morbidity and mortality rates, particularly in elderly patients. In this work, we describe a minimally invasive endoscopic alternative. Under local scalp anesthesia, a rigid endoscope is inserted through a parietal burr hole in the subdural space to collapse fibrin septa and cut the internal membrane. It also allows cauterization of active bleedings and the placement of a drain under direct visualization. The endoscopic treatment of septated CSH represents a minimally invasive alternative to craniotomy especially for the internal membranectomy.

The challenges of numerically simulating analogue brittle thrust wedges

NASA Astrophysics Data System (ADS)

Buiter, Susanne; Ellis, Susan

2017-04-01

Fold-and-thrust belts and accretionary wedges form when sedimentary and crustal rocks are compressed into thrusts and folds in the foreland of an orogen or at a subduction trench. For over a century, analogue models have been used to investigate the deformation characteristics of such brittle wedges. These models predict wedge shapes that agree with analytical critical taper theory and internal deformation structures that well resemble natural observations. In a series of comparison experiments for thrust wedges, called the GeoMod2004 (1,2) and GeoMod2008 (3,4) experiments, it was shown that different numerical solution methods successfully reproduce sandbox thrust wedges. However, the GeoMod2008 benchmark also pointed to the difficulties of representing frictional boundary conditions and sharp velocity discontinuities with continuum numerical methods, in addition to the well-known challenges of numerical plasticity. Here we show how details in the numerical implementation of boundary conditions can substantially impact numerical wedge deformation. We consider experiment 1 of the GeoMod2008 brittle thrust wedge benchmarks. This experiment examines a triangular thrust wedge in the stable field of critical taper theory that should remain stable, that is, without internal deformation, when sliding over a basal frictional surface. The thrust wedge is translated by lateral displacement of a rigid mobile wall. The corner between the mobile wall and the subsurface is a velocity discontinuity. Using our finite-element code SULEC, we show how different approaches to implementing boundary friction (boundary layer or contact elements) and the velocity discontinuity (various smoothing schemes) can cause the wedge to indeed translate in a stable manner or to undergo internal deformation (which is a fail). We recommend that numerical studies of sandbox setups not only report the details of their implementation of boundary conditions, but also document the modelling attempts that failed. References 1. Buiter and the GeoMod2004 Team, 2006. The numerical sandbox: comparison of model results for a shortening and an extension experiment. Geol. Soc. Lond. Spec. Publ. 253, 29-64 2. Schreurs and the GeoMod2004 Team, 2006. Analogue benchmarks of shortening and extension experiments. Geol. Soc. Lond. Spec. Publ. 253, 1-27 3. Buiter, Schreurs and the GeoMod2008 Team, 2016. Benchmarking numerical models of brittle thrust wedges, J. Struct. Geol. 92, 140-177 4. Schreurs, Buiter and the GeoMod2008 Team, 2016. Benchmarking analogue models of brittle thrust wedges, J. Struct. Geol. 92, 116-13

Seasonal Ice Wedge Dynamics in Fosheim Peninsula, Ellesmere Island, Nunavut

NASA Astrophysics Data System (ADS)

Ward, M. K.; Pollard, W. H.

2017-12-01

Areas with ice-rice permafrost are vulnerable to thermokarst (lowering of the land surface from melting ground ice). The Fosheim Peninsula on Ellesmere Island, Nunavut is a high Arctic polar desert system with cold permafrost 500 m thick that is ice-rich in the upper 20 - 30 m. Our team has been monitoring changing permafrost conditions on the Fosheim since 1990. In this area ground ice consists mainly of ice-wedge ice and massive tabular ice bodies. With a mean annual temperature of - 19°C, the area is still sensitive to thermokarst as experienced in 2012; one of the warmest summers on record there was a three-fold increase in thermokarst, with the accelerated deepening of ice wedge troughs and the development of retrogressive thaw slumps. In this study, 7 ice wedges were monitored for 7 weeks in July and August, 2017. Ice wedges were chosen to represent different conditions including varying tough depths (0.36 m to 1.2 m), secondary wedge, varying plant cover (heavily covered to bare soil) and one wedge initially experienced ponding from snow melt that subsequently drained. Data collected included active layer depth measurements, soil moisture, ground temperatures at ice wedge through and polygon centres, dGPS and GPR surveys. Using Worldview 2 satellite imagery from 2008, 2012, 2016, these sites were compared to assess changes in polygons at a landscape scale. Ice wedges are ubiquitous to the arctic but may respond differently within different high Arctic environments. With the majority of studies being focused in the lower arctic, this study provides important field data from a high arctic site.

The chronology of Late Pleistocene thermal contraction cracking derived from sand wedge OSL dating in central and southern France

NASA Astrophysics Data System (ADS)

Andrieux, Eric; Bateman, Mark D.; Bertran, Pascal

2018-03-01

Much of France remained unglaciated during the Late Quaternary and was subjected to repeated phases of periglacial activity. Numerous periglacial features have been reported but disentangling the environmental and climatic conditions they formed under, the timing and extent of permafrost and the role of seasonal frost has remained elusive. The primary sandy infillings of relict sand-wedges and composite-wedge pseudomorphs record periglacial activity. As they contain well-bleached quartz-rich aeolian material they are suitable for optically stimulated luminescence dating (OSL). This study aims to reconstruct when wedge activity took place in two regions of France; Northern Aquitaine and in the Loire valley. Results from single-grain OSL measurements identify multiple phases of activity within sand wedges which suggest that wedge activity in France occurred at least 11 times over the last 100 ka. The most widespread events of thermal contraction cracking occurred between ca. 30 and 24 ka (Last Permafrost Maximum) which are concomitant with periods of high sand availability (MIS 2). Although most phases of sand-wedge growth correlate well with known Pleistocene cold periods, the identification of wedge activity during late MIS 5 and the Younger Dryas strongly suggests that these features do not only indicate permafrost but also deep seasonal ground freezing in the context of low winter insolation. These data also suggest that the overall young ages yielded by North-European sand-wedges likely result from poor record of periglacial periods concomitant with low sand availability and/or age averaging inherent with standard luminescence methods.

An Experimental Investigation of Transonic Flow Past Two-Dimensional Wedge and Circular-Arc Sections Using A Mach-Zehnder Interferometer

NASA Technical Reports Server (NTRS)

Bryson, Arthur Earl, Jr

1952-01-01

Report presents the results of interferometer measurements of the flow field near two-dimensional wedge and circular-arc sections of zero angle of attack at high-subsonic and low-supersonic velocities. Both subsonic flow with local supersonic zone and supersonic flow with detached shock wave have been investigated. Pressure distributions and drag coefficients as a function of Mach number have been obtained. The wedge data are compared with the theoretical work on flow past wedge sections of Guderley and Yoshihara, Vincenti and Wagner, and Cole. Pressure distributions and drag coefficients for the wedge and circular-arc sections are presented throughout the entire transonic range of velocities.

Mechanical coupling for a rotor shaft assembly of dissimilar materials

DOEpatents

Shi, Jun [Glastonbury, CT; Bombara, David [New Hartford, CT; Green, Kevin E [Broad Brook, CT; Bird, Connic [Rocky Hill, CT; Holowczak, John [South Windsor, CT

2009-05-05

A mechanical coupling for coupling a ceramic disc member to a metallic shaft includes a first wedge clamp and a second wedge clamp. A fastener engages a threaded end of a tie-bolt to sandwich the ceramic disc between the wedge clamps. An axial spring is positioned between the fastener and the second wedge clamp to apply an axial preload along the longitudinal axis. Another coupling utilizes a rotor shaft end of a metallic rotor shaft as one wedge clamp. Still another coupling includes a solid ceramic rotor disc with a multiple of tie-bolts radially displaced from the longitudinal axis to exert the preload on the solid ceramic rotor disc.

Effect of a trade between boattail angle and wedge size on the performance of a nonaxisymmetric wedge nozzle

NASA Technical Reports Server (NTRS)

Carson, George T., Jr.; Bare, E. Ann; Burley, James R., II

1987-01-01

An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the effect of a boattail angle and wedge-size trade on the performance of nonaxisymmetric wedge nozzles installed on a generic twin-engine fighter aircraft model. Test data were obtained at static conditions and at Mach numbers from 0.60 to 1.25. Angle of attack was held constant at 0 deg. High-pressure air was used to simulate jet exhaust, and the nozzle pressure ratio was varied from 1.0 (jet off) to slightly over 15.0. For the configurations studied, the results indicate that wedge size can be reduced without affecting aeropropulsive performance.

28. VIEW EAST FROM DECKING ON SOUTHWEST CORNER OF PIVOT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

28. VIEW EAST FROM DECKING ON SOUTHWEST CORNER OF PIVOT PIER, DRIVE SYSTEM FOR SWING-SPAN INCLUDES: (from left to right) ELECTRIC LINE FROM SHORE (bottom left), TRACK AND RAIL ON CONCRETE PIER, ELECTRIC MOTOR, GASOLINE MOTOR, SHAFTS TO WEDGE DRIVE CRANKS, WEDGE DRIVE DRIVE SHAFT, WEDGE DRIVE GEAR BOX, AND (on right) GEARING FOR MANUAL WEDGE DRIVE ACCESSED THROUGH BRIDGE DECK - Tipers Bridge, Spanning Great Wicomico River at State Route 200, Kilmarnock, Lancaster County, VA

What happens to full-f gyrokinetic transport and turbulence in a toroidal wedge simulation?

DOE PAGES

Kim, Kyuho; Chang, C. S.; Seo, Janghoon; ...

2017-01-24

Here, in order to save the computing time or to fit the simulation size into a limited computing hardware in a gyrokinetic turbulence simulation of a tokamak plasma, a toroidal wedge simulation may be utilized in which only a partial toroidal section is modeled with a periodic boundary condition in the toroidal direction. The most severe restriction in the wedge simulation is expected to be in the longest wavelength turbulence, i.e., ion temperature gradient (ITG) driven turbulence. The global full-f gyrokinetic code XGC1 is used to compare the transport and turbulence properties from a toroidal wedge simulation against the fullmore » torus simulation in an ITG unstable plasma in a model toroidal geometry. It is found that (1) the convergence study in the wedge number needs to be conducted all the way down to the full torus in order to avoid a false convergence, (2) a reasonably accurate simulation can be performed if the correct wedge number N can be identified, (3) the validity of a wedge simulation may be checked by performing a wave-number spectral analysis of the turbulence amplitude |δΦ| and assuring that the variation of δΦ between the discrete kθ values is less than 25% compared to the peak |δΦ|, and (4) a frequency spectrum may not be used for the validity check of a wedge simulation.« less

What happens to full-f gyrokinetic transport and turbulence in a toroidal wedge simulation?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Kyuho; Chang, C. S.; Seo, Janghoon

Here, in order to save the computing time or to fit the simulation size into a limited computing hardware in a gyrokinetic turbulence simulation of a tokamak plasma, a toroidal wedge simulation may be utilized in which only a partial toroidal section is modeled with a periodic boundary condition in the toroidal direction. The most severe restriction in the wedge simulation is expected to be in the longest wavelength turbulence, i.e., ion temperature gradient (ITG) driven turbulence. The global full-f gyrokinetic code XGC1 is used to compare the transport and turbulence properties from a toroidal wedge simulation against the fullmore » torus simulation in an ITG unstable plasma in a model toroidal geometry. It is found that (1) the convergence study in the wedge number needs to be conducted all the way down to the full torus in order to avoid a false convergence, (2) a reasonably accurate simulation can be performed if the correct wedge number N can be identified, (3) the validity of a wedge simulation may be checked by performing a wave-number spectral analysis of the turbulence amplitude |δΦ| and assuring that the variation of δΦ between the discrete kθ values is less than 25% compared to the peak |δΦ|, and (4) a frequency spectrum may not be used for the validity check of a wedge simulation.« less

The functional anatomy of Kager's fat pad in relation to retrocalcaneal problems and other hindfoot disorders.

PubMed

Theobald, P; Bydder, G; Dent, C; Nokes, L; Pugh, N; Benjamin, M

2006-01-01

Kager's fat pad is a mass of adipose tissue occupying Kager's triangle. By means of a combined magnetic resonance imaging, ultrasound, gross anatomical and histological study, we show that it has three regions that are closely related to the sides of the triangle. Thus, it has parts related to the Achilles and flexor hallucis longus (FHL) tendons and a wedge of fat adjacent to the calcaneus. The calcaneal wedge moves into the bursa during plantarflexion, as a consequence of both an upward displacement of the calcaneus relative to the wedge and a downward displacement of the wedge relative to the calcaneus. During dorsiflexion, the bursal wedge is retracted. The movements are promoted by the tapering shape of the bursal wedge and by its deep synovial infolds. Fibrous connections linking the fat to the Achilles tendon anchor and stabilize it proximally and thus contribute to the motility of its tip. We conclude that the three regions of Kager's fat pad have specialized functions: an FHL part which contributes to moving the bursal wedge during plantarflexion, an Achilles part which protects blood vessels entering this tendon, and a bursal wedge which we suggest minimizes pressure changes in the bursa. All three regions contribute to reducing the risk of tendon kinking and each may be implicated in heel pain syndromes.

Mechanics of forearc basins

NASA Astrophysics Data System (ADS)

Cassola, Teodoro; Willett, Sean D.; Kopp, Heidrun

2010-05-01

In this study, the mechanics of forearc basins will be the object of a numerical investigation to understand the relationships between wedge deformation and forearc basin formation. The aim of this work is to gain an insight into the dynamics of the formation of the forearc basin, in particular the mechanism of formation of accommodation space and the preservation of basin stratigraphy. Our tool is a two-dimensional numerical model that includes the rheological properties of the rock, including effective internal friction angle, effective basal friction angle and thermally-dependent viscosity. We also simulate different sedimentation rates in the basin, to study the influence of underfilled and overfilled basin conditions on wedge deformation. The stratigraphy of the basin will also be studied, because in underfilled conditions the sediments are more likely to undergo tectonic deformation due to inner wedge deformation. We compare the numerical model with basins along the Sunda-Java Trench. This margin shows a variety of structural-settings and basin types including underfilled and overfilled basins and different wedge geometries. We interpret and document these structural styles, using depth migrated seismic sections of the Sunda Trench, obtained in three surveys, GINCO (11/98 - 01/99), MERAMEX (16/09/04 - 7/10/04) and SINDBAD (9/10/06 - 9/11/06) and made available through the IFM-GEOMAR and the Bundesanstalt für Geowissenschaften and Rohstoffe (BGR). One important aspect of these margins that we observe is the presence of a dynamic backstop, characterized by older accreted material, that, although deformed during and after accretion, later becomes a stable part of the upper plate. We argue that, following critical wedge theory, it entered into the stable field of a wedge either by steepening or weakening of the underlying detachment. As a stable wedge, this older segment of the wedge acts as a mechanical backstop for the frontal deforming wedge. This dynamic backstop moves seaward in time, in response to isostatic loading by the growing wedge, or due to seaward retreat of the slab with a consequent steepening of the base of the wedge.

Three-Dimensional Vertebral Wedging in Mild and Moderate Adolescent Idiopathic Scoliosis

PubMed Central

Scherrer, Sophie-Anne; Begon, Mickaël; Leardini, Alberto; Coillard, Christine; Rivard, Charles-Hilaire; Allard, Paul

2013-01-01

Background Vertebral wedging is associated with spinal deformity progression in adolescent idiopathic scoliosis. Reporting frontal and sagittal wedging separately could be misleading since these are projected values of a single three-dimensional deformation of the vertebral body. The objectives of this study were to determine if three-dimensional vertebral body wedging is present in mild scoliosis and if there are a preferential vertebral level, position and plane of deformation with increasing scoliotic severity. Methodology Twenty-seven adolescent idiopathic scoliotic girls with mild to moderate Cobb angles (10° to 50°) participated in this study. All subjects had at least one set of bi-planar radiographs taken with the EOS® X-ray imaging system prior to any treatment. Subjects were divided into two groups, separating the mild (under 20°) from the moderate (20° and over) spinal scoliotic deformities. Wedging was calculated in three different geometric planes with respect to the smallest edge of the vertebral body. Results Factorial analyses of variance revealed a main effect for the scoliosis severity but no main effect of vertebral Levels (apex and each of the three vertebrae above and below it) (F = 1.78, p = 0.101). Main effects of vertebral Positions (apex and above or below it) (F = 4.20, p = 0.015) and wedging Planes (F = 34.36, p<0.001) were also noted. Post-hoc analysis demonstrated a greater wedging in the inferior group of vertebrae (3.6°) than the superior group (2.9°, p = 0.019) and a significantly greater wedging (p≤0.03) along the sagittal plane (4.3°). Conclusions Vertebral wedging was present in mild scoliosis and increased as the scoliosis progressed. The greater wedging of the inferior group of vertebrae could be important in estimating the most distal vertebral segment to be restrained by bracing or to be fused in surgery. Largest vertebral body wedging values obtained in the sagittal plane support the claim that scoliosis could be initiated through a hypokyphosis. PMID:23977058

Modeling Diverse Pathways to Age Progressive Volcanism in Subduction Zones.

NASA Astrophysics Data System (ADS)

Kincaid, C. R.; Szwaja, S.; Sylvia, R. T.; Druken, K. A.

2015-12-01

One of the best, and most challenging clues to unraveling mantle circulation patterns in subduction zones comes in the form of age progressive volcanic and geochemical trends. Hard fought geological data from many subduction zones, like Tonga-Lau, the Cascades and Costa-Rica/Nicaragua, reveal striking temporal patterns used in defining mantle flow directions and rates. We summarize results from laboratory subduction models showing a range in circulation and thermal-chemical transport processes. These interaction styles are capable of producing such trends, often reflecting apparent instead of actual mantle velocities. Lab experiments use a glucose working fluid to represent Earth's upper mantle and kinematically driven plates to produce a range in slab sinking and related wedge transport patterns. Kinematic forcing assumes most of the super-adiabatic temperature gradient available to drive major downwellings is in the tabular slabs. Moreover, sinking styles for fully dynamic subduction depend on many complicating factors that are only poorly understood and which can vary widely even for repeated parameter combinations. Kinematic models have the benefit of precise, repeatable control of slab motions and wedge flow responses. Results generated with these techniques show the evolution of near-surface thermal-chemical-rheological heterogeneities leads to age progressive surface expressions in a variety of ways. One set of experiments shows that rollback and back-arc extension combine to produce distinct modes of linear, age progressive melt delivery to the surface through a) erosion of the rheological boundary layer beneath the overriding plate, and deformation and redistribution of both b) mantle residuum produced from decompression melting and c) formerly active, buoyant plumes. Additional experiments consider buoyant diapirs rising in a wedge under the influence of rollback, back-arc spreading and slab-gaps. Strongly deflected diapirs, experiencing variable rise rates, also commonly surface as linear, age progressive tracks. Applying these results to systems like the Cascades and Tonga-Lau suggest there are multiple ways to produce timing trends due both to linear flows and waves of heterogeneity obliquely impacting surface plates.

Precision zero-home locator

DOEpatents

Stone, William J.

1986-01-01

A zero-home locator includes a fixed phototransistor switch and a moveable actuator including two symmetrical, opposed wedges, each wedge defining a point at which switching occurs. The zero-home location is the average of the positions of the points defined by the wedges.

Precision zero-home locator

DOEpatents

Stone, W.J.

1983-10-31

A zero-home locator includes a fixed phototransistor switch and a moveable actuator including two symmetrical, opposed wedges, each wedge defining a point at which switching occurs. The zero-home location is the average of the positions of the points defined by the wedges.

[Extendable Cords to Prevent Tumbling of a Suction Device during Craniotomy].

PubMed

Shimizu, Satoru; Mochizuki, Takahiro; Osawa, Shigeyuki; Sekiguchi, Tomoko; Koizumi, Hiroyuki; Kumabe, Toshihiro

2016-02-01

Suction is necessary during craniotomy, and intraoperative tumbling of the suction device interrupts operative procedures. To avoid this, we developed a technique that would fasten the device to an extendable cord as is used to secure cell phones. We used this technique in more than 300 craniotomies at the specific point of time when the suction device tends to tumble, i. e., during the opening and closure of a wound, which requires frequent instrument exchanges. Extendable cords fastened to the tip of the suction hose using a gift tie were attached to the drapes to secure the suction device next to the operative field. During the operation, the extendable cord followed the suction device manipulations. Consequently, although there was some tension in the cord during its extension, the maneuverability of the suction device was maintained. As the hanging suction device was closer to the operative field than devices stored in conventional pockets, its manipulation was easier and quicker. Upon release, the suction device automatically returned to its original position without distracting the surgeon. Tumbling of the device was prevented, and there were no procedure-related complications. Our simple modification using extendable cords prevented tumbling, avoided unnecessary replacements, and eased the manipulation of a suction device.

Awake Craniotomy for Tumor Resection: Further Optimizing Therapy of Brain Tumors.

PubMed

Mehdorn, H Maximilian; Schwartz, Felix; Becker, Juliane

2017-01-01

In recent years more and more data have emerged linking the most radical resection to prolonged survival in patients harboring brain tumors. Since total tumor resection could increase postoperative morbidity, many methods have been suggested to reduce the risk of postoperative neurological deficits: awake craniotomy with the possibility of continuous patient-surgeon communication is one of the possibilities of finding out how radical a tumor resection can possibly be without causing permanent harm to the patient.In 1994 we started to perform awake craniotomy for glioma resection. In 2005 the use of intraoperative high-field magnetic resonance imaging (MRI) was included in the standard tumor therapy protocol. Here we review our experience in performing awake surgery for gliomas, gained in 219 patients.Patient selection by the operating surgeon and a neuropsychologist is of primary importance: the patient should feel as if they are part of the surgical team fighting against the tumor. The patient will undergo extensive neuropsychological testing, functional MRI, and fiber tractography in order to define the relationship between the tumor and the functionally relevant brain areas. Attention needs to be given at which particular time during surgery the intraoperative MRI is performed. Results from part of our series (without and with ioMRI scan) are presented.

Effects of music listening on anxiety and physiological responses in patients undergoing awake craniotomy.

PubMed

Wu, Pao-Yuan; Huang, Mei-Lin; Lee, Wen-Ping; Wang, Chi; Shih, Whei-Mei

2017-06-01

The purpose of this study was to explore the effects of music listening on the level of anxiety and physiological responses for awake craniotomy. An experimental design with randomization was applied in this study. Participants in experimental group (19 patients) selected and listened music at their preferences in the waiting room and throughout the entire surgical procedure in addition to usual care while control group (19 patients) only gave usual care. State-Trait Anxiety Inventory (STAI), heartbeat, breathing, and blood pressure were collected for analysis. The results of this study showed that after music listening, there was significant decrease in the level of anxiety (p<.001). The findings also showed that the music intervention significantly reduced heartbeat rate 84.5 (p<.004), systolic pressure 42 (p<.001), and diastolic pressure 38 (p<.001) over time. We concluded that music listening is associated with a decreased level of anxiety and distress after awake craniotomy patients. The results of this study can provide perioperative nursing care in providing music listening when patients were in the waiting room and during surgery to reduce the anxiety so as to reach the goal of human care and improve perioperative nursing care. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

A novel tablet computer platform for advanced language mapping during awake craniotomy procedures.

PubMed

Morrison, Melanie A; Tam, Fred; Garavaglia, Marco M; Golestanirad, Laleh; Hare, Gregory M T; Cusimano, Michael D; Schweizer, Tom A; Das, Sunit; Graham, Simon J

2016-04-01

A computerized platform has been developed to enhance behavioral testing during intraoperative language mapping in awake craniotomy procedures. The system is uniquely compatible with the environmental demands of both the operating room and preoperative functional MRI (fMRI), thus providing standardized testing toward improving spatial agreement between the 2 brain mapping techniques. Details of the platform architecture, its advantages over traditional testing methods, and its use for language mapping are described. Four illustrative cases demonstrate the efficacy of using the testing platform to administer sophisticated language paradigms, and the spatial agreement between intraoperative mapping and preoperative fMRI results. The testing platform substantially improved the ability of the surgeon to detect and characterize language deficits. Use of a written word generation task to assess language production helped confirm areas of speech apraxia and speech arrest that were inadequately characterized or missed with the use of traditional paradigms, respectively. Preoperative fMRI of the analogous writing task was also assistive, displaying excellent spatial agreement with intraoperative mapping in all 4 cases. Sole use of traditional testing paradigms can be limiting during awake craniotomy procedures. Comprehensive assessment of language function will require additional use of more sophisticated and ecologically valid testing paradigms. The platform presented here provides a means to do so.

Intraoperative Subcortical Electrical Mapping of the Optic Tract in Awake Surgery Using a Virtual Reality Headset.

PubMed

Mazerand, Edouard; Le Renard, Marc; Hue, Sophie; Lemée, Jean-Michel; Klinger, Evelyne; Menei, Philippe

2017-01-01

Brain mapping during awake craniotomy is a well-known technique to preserve neurological functions, especially the language. It is still challenging to map the optic radiations due to the difficulty to test the visual field intraoperatively. To assess the visual field during awake craniotomy, we developed the Functions' Explorer based on a virtual reality headset (FEX-VRH). The impaired visual field of 10 patients was tested with automated perimetry (the gold standard examination) and the FEX-VRH. The proof-of-concept test was done during the surgery performed on a patient who was blind in his right eye and presenting with a left parietotemporal glioblastoma. The FEX-VRH was used intraoperatively, simultaneously with direct subcortical electrostimulation, allowing identification and preservation of the optic radiations. The FEX-VRH detected 9 of the 10 visual field defects found by automated perimetry. The patient who underwent an awake craniotomy with intraoperative mapping of the optic tract using the FEX-VRH had no permanent postoperative visual field defect. Intraoperative visual field assessment with the FEX-VRH during direct subcortical electrostimulation is a promising approach to mapping the optical radiations and preventing a permanent visual field defect during awake surgery for epilepsy or tumor. Copyright © 2016 Elsevier Inc. All rights reserved.

Consequences of the presence of a weak fault on the stress and strain within an active margin

NASA Astrophysics Data System (ADS)

Conin, M.; Henry, P.; Godard, V.; Bourlange, S.

2009-12-01

Accreting margins often display an outer thrust and fold belt and an inner forearc domain overlying the subduction plate. Assuming that this overlying material behaves as Coulomb material, the outer wedge and the inner wedge are classically approximated as a critical state and a stable state Coulomb wedge, respectively. Critical Coulomb wedge theory can account for the transition from wedge to forearc. However, it cannot be used to determine the state of stress in the transition zone, nor the consequences of a discontinuity within the margin. The presence of a discontinuity such as a splay fault having a low effective friction coefficient should affect the stress state within the wedge, at least locally around the splay fault. Moreover, the effective friction coefficient of the seismogenic zone is expected to vary during the seismic cycle, and this may influence the stability of the Coulomb wedges. We use the ADELI finite element code (Chery and Hassani, 2000) to model the quasi-static stress and strain of a decollement and splay fault system, within a two dimensional elasto-plastic wedge with Drucker-Prager rheology. The subduction plane, the basal decollement of the accretionary wedge and the splay fault are modeled with contact elements. The modeled margin comprises an inner and an outer domain with distinct tapers and basal friction coefficients. For a given splay fault geometry, we evaluate the friction coefficient threshold for splay fault activation as a function of the basal friction coefficients, and examine the consequences of motion along the splay fault on stress and strain within the wedge and on the surface slope at equilibrium. Friction coefficients are varied in time to mimic the consequence of the seismic cycle on the static stress state and strain distribution. Results show the possibility of coexistence of localized extensional regime above the splay fault within a regional compressional regime. Such coexistence is consistent with stress orientation estimation made from breakouts in the Nankai accretionary prim (Kinoshita et al, 2009).

Group sequential designs for stepped-wedge cluster randomised trials

PubMed Central

Grayling, Michael J; Wason, James MS; Mander, Adrian P

2017-01-01

Background/Aims: The stepped-wedge cluster randomised trial design has received substantial attention in recent years. Although various extensions to the original design have been proposed, no guidance is available on the design of stepped-wedge cluster randomised trials with interim analyses. In an individually randomised trial setting, group sequential methods can provide notable efficiency gains and ethical benefits. We address this by discussing how established group sequential methodology can be adapted for stepped-wedge designs. Methods: Utilising the error spending approach to group sequential trial design, we detail the assumptions required for the determination of stepped-wedge cluster randomised trials with interim analyses. We consider early stopping for efficacy, futility, or efficacy and futility. We describe first how this can be done for any specified linear mixed model for data analysis. We then focus on one particular commonly utilised model and, using a recently completed stepped-wedge cluster randomised trial, compare the performance of several designs with interim analyses to the classical stepped-wedge design. Finally, the performance of a quantile substitution procedure for dealing with the case of unknown variance is explored. Results: We demonstrate that the incorporation of early stopping in stepped-wedge cluster randomised trial designs could reduce the expected sample size under the null and alternative hypotheses by up to 31% and 22%, respectively, with no cost to the trial’s type-I and type-II error rates. The use of restricted error maximum likelihood estimation was found to be more important than quantile substitution for controlling the type-I error rate. Conclusion: The addition of interim analyses into stepped-wedge cluster randomised trials could help guard against time-consuming trials conducted on poor performing treatments and also help expedite the implementation of efficacious treatments. In future, trialists should consider incorporating early stopping of some kind into stepped-wedge cluster randomised trials according to the needs of the particular trial. PMID:28653550

Group sequential designs for stepped-wedge cluster randomised trials.

PubMed

Grayling, Michael J; Wason, James Ms; Mander, Adrian P

2017-10-01

The stepped-wedge cluster randomised trial design has received substantial attention in recent years. Although various extensions to the original design have been proposed, no guidance is available on the design of stepped-wedge cluster randomised trials with interim analyses. In an individually randomised trial setting, group sequential methods can provide notable efficiency gains and ethical benefits. We address this by discussing how established group sequential methodology can be adapted for stepped-wedge designs. Utilising the error spending approach to group sequential trial design, we detail the assumptions required for the determination of stepped-wedge cluster randomised trials with interim analyses. We consider early stopping for efficacy, futility, or efficacy and futility. We describe first how this can be done for any specified linear mixed model for data analysis. We then focus on one particular commonly utilised model and, using a recently completed stepped-wedge cluster randomised trial, compare the performance of several designs with interim analyses to the classical stepped-wedge design. Finally, the performance of a quantile substitution procedure for dealing with the case of unknown variance is explored. We demonstrate that the incorporation of early stopping in stepped-wedge cluster randomised trial designs could reduce the expected sample size under the null and alternative hypotheses by up to 31% and 22%, respectively, with no cost to the trial's type-I and type-II error rates. The use of restricted error maximum likelihood estimation was found to be more important than quantile substitution for controlling the type-I error rate. The addition of interim analyses into stepped-wedge cluster randomised trials could help guard against time-consuming trials conducted on poor performing treatments and also help expedite the implementation of efficacious treatments. In future, trialists should consider incorporating early stopping of some kind into stepped-wedge cluster randomised trials according to the needs of the particular trial.

Observations of Lower Mississippi River Estuarine Dynamics: Effects of the Salt Wedge on Sediment Deposition

NASA Astrophysics Data System (ADS)

Ramirez, M. T.; Allison, M. A.

2017-12-01

The lowermost Mississippi River is subject to salt-wedge estuarine conditions during seasonally low flow, when seaward flow is unable to overcome density stratification. Previous studies in the Mississippi River salt wedge have shown the deposition of a fine sediment layer accumulating several mm/day beneath the reach where the salt wedge is present. Field studies were conducted during low flow in 2012-2015 utilizing ADCP, CTD, LISST, and physical samples to observe the physics of the salt wedge reach and to calculate rates and character of sediment trapping beneath the salt wedge. The field observations were summarized using a two-layer box-model representation of the reach to calculate water and sediment budgets entering, exiting, and stored within the reach. The salt wedge reach was found to be net depositional at rates up to 1.8 mm/day. The mechanism for transferring sediment mass from the downstream-flowing fluvial layer to the upstream-flowing marine layer appears to be flocculation, evidenced in LISST data by a spike in sediment particle diameters at the halocline. Applying reach-averaged rates of sediment trapping to a time-integrated model of salt-wedge position, we calculated annual totals ranging from 0.025 to 2.2 million tons of sediment deposited beneath the salt wedge, depending on salt-wedge persistence and upstream extent. Most years this seasonal deposit is remobilized during spring flood following the low-flow estuarine season, which may affect the timing of sediment delivery to the Gulf of Mexico, as well as particulate organic carbon, whose transport trajectory mirrors that of mineral sediment. These results are also relevant to ongoing dredging efforts necessary to maintain the economically-important navigation pathway through the lower Mississippi River, as well as planned efforts to use Mississippi River sedimentary resources to build land in the degrading Louisiana deltaic coast.

Diving wedges

NASA Astrophysics Data System (ADS)

Vincent, Lionel; Kanso, Eva

2017-11-01

Diving induces large pressures during water entry, accompanied by the creation of cavity behind the diver and water splash ejected from the free water surface. To minimize impact forces, divers streamline their shape at impact. Here, we investigate the impact forces and splash evolution of diving wedges as a function of the wedge opening angle. A gradual transition from impactful to smooth entry is observed as the wedge angle decreases. After submersion, diving wedges experience significantly smaller drag forces (two-fold smaller) than immersed wedges. We characterize the shapes of the cavity and splash created by the wedge and find that they are independent of the entry velocity at short times, but that the splash exhibits distinct variations in shape at later times. Combining experimental approach and a discrete fluid particle model, we show that the splash shape is governed by a destabilizing Venturi-suction force due to air rushing between the splash and the water surface and a stabilizing force due to surface tension. These findings may have implications in a wide range of water entry problems, with applications in engineering and bio-related problems, including naval engineering, disease spreading and platform diving. This work was funded by the National Science Foundation.

Aerodynamic Analysis Over Double Wedge Airfoil

NASA Astrophysics Data System (ADS)

Prasad, U. S.; Ajay, V. S.; Rajat, R. H.; Samanyu, S.

2017-05-01

Aeronautical studies are being focused more towards supersonic flights and methods to attain a better and safer flight with highest possible performance. Aerodynamic analysis is part of the whole procedure, which includes focusing on airfoil shapes which will permit sustained flight of aircraft at these speeds. Airfoil shapes differ based on the applications, hence the airfoil shapes considered for supersonic speeds are different from the ones considered for Subsonic. The present work is based on the effects of change in physical parameter for the Double wedge airfoil. Mach number range taken is for transonic and supersonic. Physical parameters considered for the Double wedge case with wedge angle (ranging from 5 degree to 15 degree. Available Computational tools are utilized for analysis. Double wedge airfoil is analysed at different Angles of attack (AOA) based on the wedge angle. Analysis is carried out using fluent at standard conditions with specific heat ratio taken as 1.4. Manual calculations for oblique shock properties are calculated with the help of Microsoft excel. MATLAB is used to form a code for obtaining shock angle with Mach number and wedge angle at the given parameters. Results obtained from manual calculations and fluent analysis are cross checked.

Measurement of Rayleigh Wave Beams Using Angle Beam Wedge Transducers as the Transmitter and Receiver with Consideration of Beam Spreading

PubMed Central

Zhang, Shuzeng; Li, Xiongbing; Jeong, Hyunjo

2017-01-01

A theoretical model, along with experimental verification, is developed to describe the generation, propagation and reception of a Rayleigh wave using angle beam wedge transducers. The Rayleigh wave generation process using an angle beam wedge transducer is analyzed, and the actual Rayleigh wave sound source distributions are evaluated numerically. Based on the reciprocity theorem and considering the actual sound source, the Rayleigh wave beams are modeled using an area integral method. The leaky Rayleigh wave theory is introduced to investigate the reception of the Rayleigh wave using the angle beam wedge transducers, and the effects of the wave spreading in the wedge and transducer size are considered in the reception process. The effects of attenuations of the Rayleigh wave and leaky Rayleigh wave are discussed, and the received wave results with different sizes of receivers are compared. The experiments are conducted using two angle beam wedge transducers to measure the Rayleigh wave, and the measurement results are compared with the predictions using different theoretical models. It is shown that the proposed model which considers the wave spreading in both the sample and wedges can be used to interpret the measurements reasonably. PMID:28632183

Measurement of Rayleigh Wave Beams Using Angle Beam Wedge Transducers as the Transmitter and Receiver with Consideration of Beam Spreading.

PubMed

Zhang, Shuzeng; Li, Xiongbing; Jeong, Hyunjo

2017-06-20

A theoretical model, along with experimental verification, is developed to describe the generation, propagation and reception of a Rayleigh wave using angle beam wedge transducers. The Rayleigh wave generation process using an angle beam wedge transducer is analyzed, and the actual Rayleigh wave sound source distributions are evaluated numerically. Based on the reciprocity theorem and considering the actual sound source, the Rayleigh wave beams are modeled using an area integral method. The leaky Rayleigh wave theory is introduced to investigate the reception of the Rayleigh wave using the angle beam wedge transducers, and the effects of the wave spreading in the wedge and transducer size are considered in the reception process. The effects of attenuations of the Rayleigh wave and leaky Rayleigh wave are discussed, and the received wave results with different sizes of receivers are compared. The experiments are conducted using two angle beam wedge transducers to measure the Rayleigh wave, and the measurement results are compared with the predictions using different theoretical models. It is shown that the proposed model which considers the wave spreading in both the sample and wedges can be used to interpret the measurements reasonably.

Porous Titanium Wedges in Lateral Column Lengthening for Adult-Acquired Flatfoot Deformity.

PubMed

Moore, Spencer H; Carstensen, S Evan; Burrus, M Tyrrell; Cooper, Truitt; Park, Joseph S; Perumal, Venkat

2017-10-01

Lateral column lengthening (LCL) is a common procedure for reconstruction of stage II flexible adult-acquired flatfoot deformity (AAFD). The recent development of porous titanium wedges for this procedure provides an alternative to allograft and autograft. The purpose of this study was to report radiographic and clinical outcomes achieved with porous titanium wedges in LCL. A retrospective analysis of 34 feet in 30 patients with AAFD that received porous titanium wedges for LCL from January 2011 to October 2014. Deformity correction was assessed using both radiographic and clinical parameters. Radiographic correction was assessed using the lateral talo-first metatarsal angle, the talonavicular uncoverage percentage, and the first metatarsocuneiform height. The hindfoot valgus angle was measured. Patients were followed from a minimum of 6 months up to 4 years (mean 16.1 months). Postoperative radiographs demonstrated significant correction in all 3 radiographic criteria and the hindfoot valgus angle. We had no cases of nonunion, no wedge migration, and no wedges have been removed to date. The most common complication was calcaneocuboid joint pain (14.7%). Porous titanium wedges in LCL can achieve good radiographic and clinical correction of AAFD with a low rate of nonunion and other complications. Level IV: Case series.

Thermally tunable broadband terahertz metamaterials with negative refractive index

NASA Astrophysics Data System (ADS)

Li, Weili; Meng, Qinglong; Huang, Renshuai; Zhong, Zheqiang; Zhang, Bin

2018-04-01

A thermally tunable broadband metamaterials with negative refractive index (NRI) is investigated in terahertz (THz) region theoretically. The metamaterials is designed by fabricating two stand-up opposite L shape metallic structures on fused quartz substrate, and the indium antimonide (InSb) is filled in the bottom gap of the two L shape structures. The tunability is attributed to the InSb because the InSb can changes the capacitance of the gap area by adjusting the temperature. The transmission characteristics and the retrieved electromagnetic parameters of the metamaterials are analyzed. Results indicate that the resonant frequency and amplitude modulation of the metamaterials can be tuned continuously in broadband range (about 0.62 THz), and the phase modulation from - 2 to 3 rad is also achieved within broadband range (about 0.8 THz). In addition, the metamaterials shows dual-band NRI behaviors at 0 . 4- 0 . 9 THz and 1 . 06- 1 . 15 THz when the temperature increases to 400 K. The wedge-shaped prism simulations are implemented to verify the NRI characteristics and indicate that the NRI of the metamaterials can be achieved.

Surgical Craniotomy for Intracerebral Haemorrhage.

PubMed

Mendelow, A David

2015-01-01

Craniotomy is probably indicated for patients with superficial spontaneous lobar supratentorial intracerebral haemorrhage (ICH) when the level of consciousness drops below 13 within the first 8 h of the onset of the haemorrhage. Once the level drops below 9, it is probably too late to consider craniotomy for these patients, so clinical vigilance is paramount. While this statement is only backed up by evidence that is moderately strong, meta-analysis of available data suggests that it is true in the rather limited number of patients with ICH. Meta-analyses like this can often predict the results of future prospective randomised controlled trials a decade or more before the trials are completed and published. Countless such examples exist in the literature, as is the case for thrombolysis in patients with myocardial infarction in the last millennium: meta-analysis determined the efficacy more than a decade BEFORE the last trial (ISIS-2) confirmed the benefit of thrombolysis for myocardial infarction. Careful examination of the meta-analysis' Forest plots in this chapter will demonstrate why this statement is made at the outset. Other meta-analyses of surgery for ICH have also indicated that minimal interventional techniques using topical thrombolysis or endoscopy via burrholes or even twist drill aspiration may be particularly successful for the treatment of supratentorial ICH, especially when the clot is deep seated. Ongoing clinical trials (CLEAR III and MISTIE III) should confirm this in the fullness of time. There are 2 exceptions to these generalisations. First, based on trial evidence, aneurysmal ICH is best treated with surgery. Second, cerebellar ICH represents a special case because of the development of hydrocephalus, which may require expeditious drainage as the intracranial pressure rises. The cerebellar clot will then require evacuation, usually via posterior fossa craniectomy, rather than craniotomy. Technical advances suggest that image-guided surgery may improve the completeness of surgical evacuation and outcomes, regardless of which surgical technique is employed. © 2016 S. Karger AG, Basel.

Clinical study on minimally invasive liquefaction and drainage of intracerebral hematoma in the treatment of hypertensive putamen hemorrhage.

PubMed

Liang, Ke-Shan; Ding, Jian; Yin, Cheng-Bin; Peng, Li-Jing; Liu, Zhen-Chuan; Guo, Xiao; Liang, Shu-Yu; Zhang, Yong; Zhou, Sheng-Nian

2017-12-04

This study aims to compare the curative effect of different treatment methods of hypertensive putamen hemorrhage, in order to determine an ideal method of treatment; and to explore the curative effect of the application of soft channel technology-minimally invasive liquefaction and drainage of intracerebral hematoma in the treatment of hypertensive putamen hemorrhage. Patients with hypertensive cerebral hemorrhage, who were treated in our hospital from January 2015 to January 2016, were included into this study. Patients were divided into three groups: minimally invasive drainage group, internal medical treatment group and craniotomy group. In the minimally invasive drainage group, puncture aspiration and drainage were performed according to different hematoma conditions detected in brain CT, the frontal approach was selected for putamen and intracerebral hemorrhage, and drainage was reserved until the hematoma disappeared in CT detection. Drug therapy was dominated in the internal medical treatment group, while surgery under general anesthesia was performed to remove the hematoma in the craniotomy group. Post-treatment neurological function defect scores in minimally invasive drainage group and internal medical group were 16.14 ± 11.27 and 31.43 ± 10.42, respectively; and the difference was remarkably significant (P< 0.01). Post-treatment neurological function defect scores in the minimally invasive drainage group and craniotomy group were 16.14 ± 11.27 and 24.20 ± 12.23, respectively; and the difference was statistically significant (P< 0.05). There was a remarkable significant difference in ADL1-2 level during followed-up in survival patients between the minimally invasive drainage group and internal medical treatment group (P< 0.01), and there was a significant difference in followed-up mortality between these two groups (P< 0.01). Clinical observation and following-up results revealed that minimally invasive drainage treatment was superior to internal medical treatment and craniotomy.

Effects of Esmolol on the Prevention of Haemodynamic Responses to Tracheal Extubation after Craniotomy Operations

PubMed Central

Alkaya, Murat Alp; Saraçoğlu, Kemal Tolga; Pehlivan, Gökhan; Eti, Zeynep; Göğüş, Fevzi Yılmaz

2014-01-01

Objective The aim of this study was to evaluate the effects of esmolol infusion on the prevention of haemodynamic responses to tracheal extubation in patients undergoing elective craniotomy. Methods With approval from the Medical School Ethics Committee at Marmara University and the patients’ written consent, 30 patients between 20–65 years of age undergoing elective craniotomy were randomly placed in either the Group Esmolol (n=15) or the Group Control (n=15). Anaesthesia was induced with 5–7 mg kg−1 thiopental sodium, 1 μg kg−1 remifentanil, and 0.1 mg kg−1 vecuronium bromide iv, and was maintained with 1 MAC sevoflurane in oxygen-air mixture (50:50) and 0.25 μg kg−1 min−1 remifentanil infusion. At the end of the operation, patients inhaled 100% oxygen after the discontinuation of the anaesthetic agents. For Group Esmolol, 5 min before extubation 2 mg kg−1 esmolol in 50 mL was infused over 10 min (0.2 μg kg−1 min−1), while for Group Control, 50 mL saline was infused over 10 min. The quality of extubation was evaluated with a 5 point scale, recording heat rate, systolic, diastolic, and mean arterial pressures before infusion, 1 min after infusion, during extubation, and at 1, 3, 5, and 10 min after extubation. Results In the esmolol group, systolic, diastolic, and mean arterial pressures, as well as heart rate, decreased significantly after esmolol infusion and were significantly lower than in the control group after extubation (p<0.05). The ratio of patients with an extubation score of one was significantly higher in the esmolol group than in the control group (p<0.05). Conclusion We concluded that 2 mg kg−1 esmolol infusion before extubation can prevent hypertension and tachycardia caused by extubation in patients undergoing elective craniotomy. PMID:27366396

A comparison of equivolume, equiosmolar solutions of hypertonic saline and mannitol for brain relaxation during elective supratentorial craniotomy.

PubMed

Hernández-Palazón, Joaquín; Fuentes-García, Diego; Doménech-Asensi, Paloma; Piqueras-Pérez, Claudio; Falcón-Araña, Luis; Burguillos-López, Sebastián

2016-01-01

Hyperosmolar solutions have been used in neurosurgery to reduce brain volume and facilitate surgical exposure. The purpose of this study was to compare the effects of equivolume, equiosmolar solutions of mannitol and hypertonic saline (HS) on brain relaxation, intensive care unit (ICU) and hospital stay, postoperative outcomes and incidence of side-effects in patients undergoing elective supratentorial craniotomy. In a randomised, prospective, double-blind study, 60 patients undergoing elective supratentorial craniotomy were randomised 1:1 to receive 3 ml/kg of either 20% mannitol or 3% HS. The primary outcome was the surgical condition of the brain assessed by the neurosurgeon using a 4-point scale after opening the dura (1 = relaxed, 2 = satisfactory, 3 = firm and 4 = bulging). Secondary outcomes were electrolytes, blood gases, plasma osmolality and haemodynamic variables measured at 0 min, 30 min, 2 h and 6 h after infusion. Also, predefined postoperative complications, length of ICU and hospital stay were recorded. Appropriate statistical tests were used for comparison; p < 0.05 was considered significant. There was no difference in brain relaxation [mannitol, 1(1-3) versus HS, 1(1.4) points; p = 0.55]. Patients with brain midline shift showed a worse response to hyperosmolar solutions than those without midline shift: 37% versus 8%, respectively; OR = 6.6 (95% CI, 1.54-28.83); p = 0.006. Plasma osmolality increased during the study period (6 h) in both the groups (p < 0.05 compared with baseline). No significant differences in postoperative complications or length of ICU and hospital stay were observed between the groups. Single doses of 3 ml/kg of 20% mannitol and 3% HS are safe and effective for intraoperative brain debulking during elective supratentorial craniotomy, but less effective in patients with pre-existing mass effect and midline shift.

28. REPRESENTATIVE CENTER WEDGE. BALANCE WHEELS ON TRACK, WITH RACK ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

28. REPRESENTATIVE CENTER WEDGE. BALANCE WHEELS ON TRACK, WITH RACK TO OUTSIDE, SHOWN TO RIGHT OF THE WEDGE. PHOTO TAKEN AT SOUTH SWING SPAN. - George P. Coleman Memorial Bridge, Spanning York River at U.S. Route 17, Yorktown, York County, VA

Ultrasonic transducer with laminated coupling wedge

DOEpatents

Karplus, Henry H. B.

1976-08-03

An ultrasonic transducer capable of use in a high-temperature environment incorporates a laminated metal coupling wedge including a reflecting edge shaped as a double sloping roof and a transducer crystal backed by a laminated metal sound absorber disposed so as to direct sound waves through the coupling wedge and into a work piece, reflections from the interface between the coupling wedge and the work piece passing to the reflecting edge. Preferably the angle of inclination of the two halves of the reflecting edge are different.

Influence of the substorm current wedge on the Dst index

NASA Astrophysics Data System (ADS)

Friedrich, Erena; Rostoker, Gordon; Connors, Martin G.; McPherron, R. L.

1999-03-01

One of the major questions confronting researchers studying the nature of the solar-terrestrial interaction centers around whether or not the substorm expansive phase has any causal effect on the growth of the storm time ring current. This question is often addressed by using the Dst index as a proxy for the storm time ring current and inspecting the main phase growth of Dst in the context of the substorm expansive phases which occur in the same time frame as the ring current growth. In the past it has been assumed that the magnetic effects of the substorm current wedge have little influence on the Dst index because the current wedge is an asymmetric current system, while Dst is supposed to reflect changes in the symmetric component of the ring current. In this paper we shall shown that the substorm current wedge can have a significant effect on the present Dst index, primarily as a consequence of the fact that only four stations are presently used to formulate the index. Calculations are made assuming the instantaneous magnitude of the wedge current is constant at 1 MA. Hourly values of Dst may be as much as 50° smaller than those presented here because of variation of the wedge current over the hour. We shall show how the effect of the current wedge depends on the UT of the expansive phase onset, the angular extent of the current wedge, and the locale of the closure current in the magnetosphere. The fact that the substorm current wedge is a conjugate phenomenon has an important influence on the magnitude of the expansive phase effect in the Dst index.

A Prospective, Randomized, Double-Blinded, Double-Dummy Pilot Study to Assess the Preemptive Effect of Triple Therapy with Aprepitant, Dexamethasone, and Promethazine versus Ondansetron, Dexamethasone and Promethazine on Reducing the Incidence of Postoperative Nausea and Vomiting Experienced by Patients Undergoing Craniotomy Under General Anesthesia.

PubMed

Bergese, Sergio Daniel; Puente, Erika G; Antor, Maria A; Viloria, Adolfo L; Yildiz, Vedat; Kumar, Nicolas Alexander; Uribe, Alberto A

2016-01-01

Postoperative nausea and vomiting (PONV) is among the most common distressing complications of surgery under anesthesia. Previous studies have demonstrated that patients who undergo craniotomy have incidences of nausea and vomiting as high as 50-70%. The main purpose of this pilot study is to assess the incidence of PONV by using two different prophylactic regimens in subjects undergoing a craniotomy. Thus, we designed this study to assess the efficacy and safety of triple therapy with the combination of dexamethasone, promethazine, and aprepitant versus ondansetron to reduce the incidence of PONV in patients undergoing craniotomy. This is a prospective, single center, two-armed, randomized, double-dummy, double-blind, pilot study. Subjects were randomly assigned to one of the two treatment groups. Subjects received 40 mg of aprepitant pill (or matching placebo pill) 30-60 min before induction of anesthesia and 4 mg of ondansetron IV (or 2 ml of placebo saline solution) at induction of anesthesia. In addition, all subjects received 25 mg of promethazine IV and 10 mg of dexamethasone IV at induction of anesthesia. Assessments of PONV commenced for the first 24 h after surgery and were subsequently assessed for up to 5 days. The overall incidence of PONV during the first 24 h after surgery was 31.0% (n = 15) in the aprepitant group and 36.2% (n = 17) for the ondansetron group. The median times to first emetic and significant nausea episodes were 7.6 (2.9, 48.7) and 14.3 (4.4, 30.7) hours, respectively, for the aprepitant group and 6.0 (2.2, 29.5) and 9.6 (0.7, 35.2) hours, respectively, for the ondansetron group. There were no statistically significant differences between these groups. No adverse events directly related to study medications were found. This pilot study showed similar effectiveness when comparing the two PONV prophylaxis regimens. Our data showed that both treatments could be effective regimens to prevent PONV in patients undergoing craniotomy under general anesthesia. Future trials testing new PONV prophylaxis regimens in this surgical population should be performed to gain a better understanding of how to best provide prophylactic treatment.

Development of Cone Wedge Ring Expansion Test to Evaluate Mechanical Properties of Clad Tubing Structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jy-An John

To determine the hoop tensile properties of irradiated fuel cladding in a hot cell, a cone wedge ring expansion test method was developed. A four-piece wedge insert was designed with tapered angles matched to the cone shape of a loading piston. The ring specimen was expanded in the radial direction by the lateral expansion of the wedges under the downward movement of the piston. The advantages of the proposed method are that implementation of the test setup in a hot cell is simple and easy, and that it enables a direct strain measurement of the test specimen from the piston’smore » vertical displacement soon after the wedge-clad contact resistance is initiated.« less

21 CFR 884.5200 - Hemorrhoid prevention pressure wedge.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Hemorrhoid prevention pressure wedge. 884.5200... Devices § 884.5200 Hemorrhoid prevention pressure wedge. (a) Identification. A hemorrhoid prevention... hemorrhoids associated with vaginal childbirth. (b) Classification. Class II (special controls). The special...

21 CFR 884.5200 - Hemorrhoid prevention pressure wedge.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Hemorrhoid prevention pressure wedge. 884.5200... Devices § 884.5200 Hemorrhoid prevention pressure wedge. (a) Identification. A hemorrhoid prevention... hemorrhoids associated with vaginal childbirth. (b) Classification. Class II (special controls). The special...

21 CFR 884.5200 - Hemorrhoid prevention pressure wedge.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Hemorrhoid prevention pressure wedge. 884.5200... Devices § 884.5200 Hemorrhoid prevention pressure wedge. (a) Identification. A hemorrhoid prevention... hemorrhoids associated with vaginal childbirth. (b) Classification. Class II (special controls). The special...

Wedge measures parallax separations...on large-scale 70-mm

Treesearch

Steven L. Wert; Richard J. Myhre

1967-01-01

A new parallax wedge (range: 1.5 to 2 inches) has been designed for use with large-scaled 70-mm. aerial photographs. The narrow separation of the wedge allows the user to measure small parallax separations that are characteristic of large-scale photographs.

Wedge and spring assembly for securing coils in electromagnets and dynamoelectric machines

DOEpatents

Lindner, Melvin; Cottingham, James G.

1996-03-12

A wedge and spring assembly for use in electromagnets or dynamoelectric machines having a housing with an axis therethrough and a plurality of coils supported on salient poles that extend radially inward from the housing toward the housing axis to define a plurality of interpole spaces. The wedge and spring assembly includes a nonmagnetic retainer spring and a nonmagnetic wedge. The retainer spring is formed to fit into one of the interpole spaces, and has juxtaposed ends defining between them a slit extending in a direction generally parallel to the housing axis. The wedge for insertion into the slit provides an outwardly directed force on respective portions of the juxtaposed ends to expand the slit so that respective portions of the retainer spring engage areas of the coils adjacent thereto, thereby resiliently holding the coils against their respective salient poles. The retainer spring is generally triangular shaped to fit within the interpole space, and the wedge is generally T-shaped.

Wedge and spring assembly for securing coils in electromagnets and dynamoelectric machines

DOEpatents

Lindner, M.; Cottingham, J.G.

1996-03-12

A wedge and spring assembly for use in electromagnets or dynamoelectric machines is disclosed having a housing with an axis therethrough and a plurality of coils supported on salient poles that extend radially inward from the housing toward the housing axis to define a plurality of interpole spaces. The wedge and spring assembly includes a nonmagnetic retainer spring and a nonmagnetic wedge. The retainer spring is formed to fit into one of the interpole spaces, and has juxtaposed ends defining between them a slit extending in a direction generally parallel to the housing axis. The wedge for insertion into the slit provides an outwardly directed force on respective portions of the juxtaposed ends to expand the slit so that respective portions of the retainer spring engage areas of the coils adjacent thereto, thereby resiliently holding the coils against their respective salient poles. The retainer spring is generally triangular shaped to fit within the interpole space, and the wedge is generally T-shaped. 6 figs.

Seismic evidence for a cold serpentinized mantle wedge beneath Mount St Helens

PubMed Central

Hansen, S. M.; Schmandt, B.; Levander, A.; Kiser, E.; Vidale, J. E.; Abers, G. A.; Creager, K. C.

2016-01-01

Mount St Helens is the most active volcano within the Cascade arc; however, its location is unusual because it lies 50 km west of the main axis of arc volcanism. Subduction zone thermal models indicate that the down-going slab is decoupled from the overriding mantle wedge beneath the forearc, resulting in a cold mantle wedge that is unlikely to generate melt. Consequently, the forearc location of Mount St Helens raises questions regarding the extent of the cold mantle wedge and the source region of melts that are responsible for volcanism. Here using, high-resolution active-source seismic data, we show that Mount St Helens sits atop a sharp lateral boundary in Moho reflectivity. Weak-to-absent PmP reflections to the west are attributed to serpentinite in the mantle-wedge, which requires a cold hydrated mantle wedge beneath Mount St Helens (<∼700 °C). These results suggest that the melt source region lies east towards Mount Adams. PMID:27802263

Interaction of disturbances with an oblique detonation wave attached to a wedge

NASA Technical Reports Server (NTRS)

Lasseigne, D. G.; Hussaini, M. Y.

1993-01-01

The linear response of an oblique overdriven detonation to impose free stream disturbances or to periodic movements of the wedge is examined. The free stream disturbances are assumed to be steady vorticity waves and the wedge motions are considered to be time periodic oscillations either about a fixed pivot point or along the plane of symmetry of the wedge aligned with the incoming stream. The detonation is considered to be a region of infinitesimal thickness in which a finite amount of heat is released. The response to the imposed disturbances is a function of the Mach number of the incoming flow, the wedge angle, and the exothermocity of the reaction within the detonation. It is shown that as the degree of overdrive increases, the amplitude of the response increases significantly; furthermore, a fundamental difference in the dependence of the response on the parameters of the problem is found between the response to a free stream disturbance and to a disturbance emanating from the wedge surface.

The Ronda peridotite (Spain): A natural template for seismic anisotropy in subduction wedges

NASA Astrophysics Data System (ADS)

Précigout, Jacques; Almqvist, Bjarne S. G.

2014-12-01

The origin of seismic anisotropy in mantle wedges remains elusive. Here we provide documentation of shear wave anisotropy (AVs) inferred from mineral fabric across a lithosphere-scale vestige of deformed mantle wedge in the Ronda peridotite. As predicted for most subduction wedges, this natural case exposes a transition from A-type to B-type olivine fabric that occurs with decreasing temperature and enhanced grain boundary sliding at the expense of dislocation creep. We show that B-type fabric AVs (maximum of 6%) does not support geophysical observations and modeling, which requires 8% AVs. However, an observed transitional olivine fabric (A/B) develops at intermediate temperatures (800-1000°C) and can generate AVs ≥ 8%. We predict that the A/B-type fabric can account for shear wave splitting in contrasting subduction settings, exemplified by the Ryukyu and Honshu subduction wedges. The Ronda peridotite therefore serves as a natural template to decipher the mantle wedge deformation from seismic anisotropy.

Design and simulation of MEMS-actuated adjustable optical wedge for laser beam scanners

NASA Astrophysics Data System (ADS)

Bahgat, Ahmed S.; Zaki, Ahmed H.; Abdo Mohamed, Mohamed; El Sherif, Ashraf Fathy

2018-01-01

This paper introduces both optical and mechanical design and simulation of large static deflection MOEMS actuator. The designed device is in the form of an adjustable optical wedge (AOW) laser scanner. The AOW is formed of 1.5-mm-diameter plano-convex lens separated by air gap from plano-concave fixed lens. The convex lens is actuated by staggered vertical comb drive and suspended by rectangular cross-section torsion beam. An optical analysis and simulation of air separated AOW as well as detailed design, analysis, and static simulation of comb -drive are introduced. The dynamic step response of the full system is also introduced. The analytical solution showed a good agreement with the simulation results. A general global minimum optimization algorithm is applied to the comb-drive design to minimize driving voltage. A maximum comb-drive mechanical deflection angle of 12 deg in each direction was obtained under DC actuation voltage of 32 V with a settling time of 90 ms, leading to 1-mm one-dimensional (1-D) steering of laser beam with continuous optical scan angle of 5 deg in each direction. This optimization process provided a design of larger deflection actuator with smaller driving voltage compared with other conventional devices. This enhancement could lead to better performance of MOEMS-based laser beam scanners for imaging and low-speed applications.

Mechanics of Formation of Forearc Basins of Indonesia and Alaska

NASA Astrophysics Data System (ADS)

Cassola, T.; Willett, S.; Kopp, H.

2010-12-01

In this study, the mechanics of forearc basins will be the object of a numerical investigation to understand the relationships between the wedge deformation and forearc basin formation. The aim of this work is to gain insight into the dynamics of the formation of the forearc basin on top of a deforming accretionary wedge, including the mechanism of formation of accommodation space and preservation of basin stratigraphy. Our tool is a two-dimensional numerical model that includes the rheological properties of the rock, including effective internal friction angle, effective basal friction angle, thermally-activated viscosity and strain softening. We also simulate different sedimentation rates in the basin, to study the influence of underfilled and overfilled basin conditions on wedge deformation. The stratigraphy in the basin is simulated, because, as noted in earlier studies, underfilled conditions incourage tectonic deformation in the inner wedge. We compare the numerical model to basins along the Sunda-Java Trench and the Alaskan margin. The Sunda-Java Trench shows a variety of structural and basin styles including underfilled and overfilled basins and different wedge geometries along the same trench. We interprete and document these structural styles, using depth migrated seismic sections of the Sunda Trench, obtained in three surveys, GINCO (11/98 - 01/99), MERAMEX (16/09/04 - 7/10/04) and SINDBAD (9/10/06 - 9/11/06) and made available by the IFM-GEOMAR group in Kiel and the Bundesanstalt für Geowissenschaften and Rohstoffe (BGR) in Hannover. On the Alaska margin we focus on the Kenai Peninsula, Kodiak Island plateau. This segment of the margin has one of the largest accretionary wedge - forearc basin systems in the world. It also exhibits a double forearc basin system with an interior basin (Cook inlet) and an outer basin, outboard of Kodiak Island, which is a prime candidate for a negative-alpha basin, as described by Fuller et al., (Geology, 2006). A number of studies of the Alaska margin were conducted in the 1990s based out of GEOMAR. One important aspect of these margins is the presence of a dynamic backstop, characterized by older accreted material, that, although deformed during and after accretion, later becomes a stable part of the upper plate. We argue that, following critical wedge theory, it entered into the stability field of a wedge either by steepening or weakening of the underlying detachment. As a stable wedge, this older segment of the wedge acts as a mechanical backstop for the frontal deforming wedge. This dynamic backstop moves seaward in time, in response to isostatic loading by the growing wedge, or due to seaward retreat of the slab with a consequent steepening of the base of the wedge.

Comparison of autogenous cancellous bone grafting and extracorporeal shock wave therapy on osteotomy healing in the tibial tuberosity advancement procedure in dogs. Radiographic densitometric evaluation.

PubMed

Barnes, K; Lanz, O; Werre, S; Clapp, K; Gilley, R

2015-01-01

To compare optical values in the osteotomy gap created after a tibial tuberosity advancement (TTA) treated with autogenous cancellous bone graft, extracorporeal shock wave therapy, a combination of autogenous cancellous bone graft and extracorporeal shock wave therapy, and absence of both autogenous cancellous bone graft and extracorporeal shock wave therapy using densitometry. Dogs that were presented for surgical repair of a cranial cruciate ligament rupture were randomly assigned to one of four groups: TTA with autogenous cancellous bone graft (TTA-G), TTA with autogenous cancellous bone graft and extracorporeal shock wave therapy (TTA-GS), TTA with extracorporeal shock wave therapy (TTA-S), and TTA with no additional therapy (TTA-O). Mediolateral radiographs at zero, four and eight weeks after surgery were evaluated to compare healing of the osteotomy gap via densitometry. An analysis of variance was used to compare the densitometric values between groups. At four weeks after surgery, a significant difference in osteotomy gap density was noted between TTA-GS (8.4 millimetres of aluminium equivalent [mmAleq]) and TTA-S (6.1 mmAleq), and between TTA-GS (8.4 mmAleq) and TTA-O (6.4 mmAleq). There were no significant differences noted between any groups at the eight week re-evaluation. There were no significant differences in the osteotomy gap density at eight weeks after surgery regardless of the treatment modality used. The combination of autogenous cancellous bone graft and extracorporeal shock wave therapy may lead to increased radiographic density of the osteotomy gap in the first four weeks after surgery. Densitometry using an aluminium step wedge is a feasible method for comparison of bone density after TTA in dogs.

Redistribution of knee stress using laterally wedged insole intervention: Finite element analysis of knee-ankle-foot complex.

PubMed

Liu, Xuan; Zhang, Ming

2013-01-01

Laterally wedged insoles are widely applied in the conservative treatment for medial knee osteoarthritis. Experimental studies have been conducted to understand the effectiveness of such an orthotic intervention. However, the information was limited to the joint external loading such as knee adduction moment. The internal stress distribution is difficult to be obtained from in vivo experiment alone. Thus, a three-dimensional finite element model of the human knee-ankle-foot complex, together with orthosis, was developed in this study and used to investigate the redistribution of knee stress using laterally wedged insole intervention. Laterally wedged insoles with wedge angles of 0, 5, and 10° were fabricated for intervention. The subject-specific geometry of the lower extremity with details was characterized in the reconstruction of MR images. Motion analysis data and muscle forces were input to drive the model. The established finite element model was employed to investigate the loading responses of tibiofemoral articulation in three wedge angle conditions during simulated walking stance phase. With either of the 5° or 10° laterally wedged insole, significant decreases in von Mises stress and contact force at the medial femur cartilage region and the medial meniscus were predicted comparing with the 0° insole. The diminished stress and contact force at the medial compartment of the knee joint demonstrate the immediate effect of the laterally wedged insoles. The intervention may contribute to medial knee osteoarthritis rehabilitation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Two occurrences of delayed epidural hematoma in different areas following decompressive craniectomy for acute subdural hematoma in a single patient: a case report.

PubMed

Wu, Ruhong; Shi, Jia; Cao, Jiachao; Mao, Yumin; Dong, Bo

2017-12-04

Delayed epidural hematoma (DEH) following evacuation of traumatic acute subdural hematoma (ASDH) or acute epidural hematoma (EDH) is a rare but devastating complication, especially when it occurs sequentially in a single patient. A 19-year-old man who developed contralateral DEH following craniotomy for evacuation of a traumatic right-side ASDH and then developed a left-side DEH of the posterior cranial fossa after craniotomy for evacuation of the contralateral DEH. He was immediately returned to the operating room for additional surgeries and his neurological outcome was satisfactory. Although DEH occurring after evacuation of ASDH or acute EDH is a rare event, timely recognition is critical to prognosis.

Linear undisplaced fracture of temporoparietal bone acting as spontaneous early decompressive craniotomy in a neonate

PubMed Central

Vankipuram, Siddharth; Balasubramanium, Srikant; Tyagi, Devendra K.; Savant, H. V.

2015-01-01

Decompressive craniotomy (DC) is used to treat intracranial hypertension associated with traumatic brain injury. Early DC is associated with better outcomes. We present a neonate with a history of fall with computed tomography scan showing a large frontoparietal contusion and associated parietal and temporal bone fracture. This acted as a spontaneous DC causing bony segment to separate due to which the edematous brain could be accommodated. Despite the presence of a large contusion, the child was neurologically intact and medically managed. The neonate presented with a posttraumatic leptomeningeal cyst 2 months later, which had to be repaired surgically. We discuss how a linear undisplaced fracture acts as spontaneous DC and the role of early DC in improving outcomes. PMID:26557171

Endoscopic Evacuation of Basal Ganglia Hemorrhage via Keyhole Approach Using an Adjustable Cannula in Comparison with Craniotomy

PubMed Central

Zhang, Heng-Zhu; Li, Yu-Ping; Yan, Zheng-cun; Wang, Xing-dong; She, Lei; Wang, Xiao-dong; Dong, Lun

2014-01-01

Neuroendoscopic (NE) surgery as a minimal invasive treatment for basal ganglia hemorrhage is a promising approach. The present study aims to evaluate the efficacy and safety of NE approach using an adjustable cannula to treat basal ganglia hemorrhage. In this study, we analysed the clinical and radiographic outcomes between NE group (21 cases) and craniotomy group (30 cases). The results indicated that NE surgery might be an effective and safe approach for basal ganglia haemorrhage, and it is also suggested that NE approach may improve good functional recovery. However, NE approach only suits the selected patient, and the usefulness of NE approach needs further randomized controlled trials (RCTs) to evaluate. PMID:24949476

Pipe gripper

DOEpatents

Moyers, S.M.

1975-12-16

A device for gripping the exterior surface of a pipe or rod is described which has a plurality of wedges, each having a concave face which engages the outer surface of the pipe and each having a smooth face opposing the concave face. The wedges are seated on and their grooved concave faces are maintained in circular alignment by tapered axial segments of an opening extending through a wedge-seating member. The wedges are allowed to slide across the tapered axial segments so that such a sliding movement acts to vary the diameter of the circular alignment.

Sojourner APXS & Wedge

NASA Image and Video Library

1997-08-27

This image of the rock "Wedge" was taken from the Sojourner rover's rear color camera on Sol 37. The position of the rover relative to Wedge is seen in MRPS 83349. The segmented rod visible in the middle of the frame is the deployment arm for the Alpha Proton X-Ray Spectrometer (APXS). The APXS, the bright, cylindrical object at the end of the arm, is positioned against Wedge and is designed to measure the rock's chemical composition. This was done successfully on the night of Sol 37. http://photojournal.jpl.nasa.gov/catalog/PIA00906

The crack and wedging problem for an orthotropic strip

NASA Technical Reports Server (NTRS)

Cinar, A.; Erdogan, F.

1982-01-01

The plane elasticity problem for an orthotropic strip containing a crack parallel to its boundaries is considered. The problem is formulated under general mixed mode loading conditions. The stress intensity factors depend on two dimensionless orthotropic constants only. For the crack problem the results are given for a single crack and two collinear cracks. The calculated results show that of the two orthotropic constants the influence of the stiffness ratio on the stress intensity factors is much more significant than that of the shear parameter. The problem of loading the strip by a rigid rectangular lengths continuous contact is maintained along the wedge strip interface; at a certain critical wedge length the separation starts at the midsection of the wedge, and the length of the separation zone increases rapidly with increasing wedge length.

Mechanically expandable annular seal

DOEpatents

Gilmore, R.F.

1983-07-19

A mechanically expandable annular reusable seal assembly to form an annular hermetic barrier between two stationary, parallel, and planar containment surfaces is described. A rotatable ring, attached to the first surface, has ring wedges resembling the saw-tooth array of a hole saw. Matching seal wedges are slidably attached to the ring wedges and have their motion restricted to be perpendicular to the second surface. Each seal wedge has a face parallel to the second surface. An annular elastomer seal has a central annular region attached to the seal wedges' parallel faces and has its inner and outer circumferences attached to the first surface. A rotation of the ring extends the elastomer seal's central region perpendicularly towards the second surface to create the fluid tight barrier. A counter rotation removes the barrier. 6 figs.

Effect of a pelvic wedge and belt on the medial and lateral hamstring muscles during knee flexion.

PubMed

Yoo, Won-Gyu

2017-01-01

[Purpose] This study developed a pelvic wedge and belt and investigated their effects on the selective activation of medial and lateral hamstring muscles during knee flexion. [Subjects and Methods] Nine adults were enrolled. The participants performed exercises without and with the pelvic wedge and belt, and the electromyographic activities of the medial and lateral hamstring muscles were recorded. [Results] The activity of the medial hamstring was increased significantly when using the pelvic wedge and belt, while the activity of the lateral hamstring did not differ significantly. [Conclusion] The pelvic wedge and belt provide a self-locked position during knee flexion in the prone position. Prone knee flexion in this position is an effective self-exercise for balanced strengthening of the medial hamstring.

Effect of a pelvic wedge and belt on the medial and lateral hamstring muscles during knee flexion

PubMed Central

Yoo, Won-gyu

2017-01-01

[Purpose] This study developed a pelvic wedge and belt and investigated their effects on the selective activation of medial and lateral hamstring muscles during knee flexion. [Subjects and Methods] Nine adults were enrolled. The participants performed exercises without and with the pelvic wedge and belt, and the electromyographic activities of the medial and lateral hamstring muscles were recorded. [Results] The activity of the medial hamstring was increased significantly when using the pelvic wedge and belt, while the activity of the lateral hamstring did not differ significantly. [Conclusion] The pelvic wedge and belt provide a self-locked position during knee flexion in the prone position. Prone knee flexion in this position is an effective self-exercise for balanced strengthening of the medial hamstring. PMID:28210048

Use of Wedge Absorbers in MICE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neuffer, D.; Summers, D.; Mohayai, T.

2017-03-01

Wedge absorbers are needed to obtain longitudinal cooling in ionization cooling. They also can be used to obtain emittance exchanges between longitudinal and transverse phase space. There can be large exchanges in emittance, even with single wedges. In the present note we explore the use of wedge absorbers in the MICE experiment to obtain transverse–longitudinal emittance exchanges within present and future operational conditions. The same wedge can be used to explore “direct” and “reverse” emittance exchange dynamics, where direct indicates a configuration that reduces momentum spread and reverse is a configuration that increases momentum spread. Analytical estimated and ICOOL andmore » G4BeamLine simulations of the exchanges at MICE parameters are presented. Large exchanges can be obtained in both reverse and direct configurations.« less

Nature of the Coastal Range Wedge Along the Rupture Area of the 2015, Illapel Chile Earthquake Mw 8.4

NASA Astrophysics Data System (ADS)

Farías, M.; Comte, D.; Roecker, S. W.; Brandon, M. T.

2017-12-01

Wedge theory is usually applied to the pro-side of active subduction margins, where fold-and-thrust belts related to frontal accretion develop, but rarely to the entire wedge, where the retro-side is also relevant. We present a new 3D body wave tomographic image that combines data from the Chile-Illapel Aftershock Experiment (CHILLAX) with previous temporary seismic networks, with the aim of illuminating the nature of the wedge of the continental margin above the seismogenic part of the subducting slab. The downdip extent of the coupled part, called the S-point in the wedge theory, corresponds to the place where upper plate completely decouples from the subducting slab. This point is characterized by a Vp/Vs contrast at about 60 km depth that extends upward-and-eastward in a west-dipping ramp-like geometry. This ramp emerges about 180 km from the trench, near the topographic break related to the front of the Andean retro-side. The Coastal wedge domain is characterized by a monotonous east-dipping homocline with the older rocks of this region along the coast. The offshore region, corresponding to the pro-side, exhibits normal faulting and a very small frontal accretionary complex. Normal faulting in this region is related to rapid uplift of marine terraces since ca. 2 Ma, suggesting strong basal accretion and thus high friction on the thrust. In fact, the epicentral region of the 2015 Illapel Earthquake coincides with the highest elevations along the coast, i.e., the region with the highest slope of the margin. In this region, the lack of a continental forearc basin suggests an overlapping between the Andean and Coastal wedges. The western edge of the Andean wedge is also part of the homocline about 10 km east of the topographic boundary between both wedges, suggesting that the Coastal wedge has been deforming a part of the retro-side of the Andean wedge during the Miocene. The east-ward tilting of the retro-side was acquired mainly before the late Miocene, since at least the Late Cretaceous, before the proposed arrival of the Juan Fernandez ridge at this area and the consequent flat slab that characterize this part of the margin in the Present.

Impacts of shape and height of upstream roof on airflow and pollutant dispersion inside an urban street canyon.

PubMed

Huang, Yuan-Dong; He, Wen-Rong; Kim, Chang-Nyung

2015-02-01

A two-dimensional numerical model for simulating flow and pollutant dispersion in an urban street canyon is firstly developed using the FLUENT code and then validated against the wind tunnel results. After this, the flow field and pollutant dispersion inside an urban street canyon with aspect ratio W/H = 1 are examined numerically considering five different shapes (vaulted, trapezoidal, slanted, upward wedged, and downward wedged roofs) as well as three different roof height to building height ratios (Z H /H = 1/6, 1/3, and 1/2) for the upstream building roof. The results obtained reveal that the shape and height of an upstream roof have significant influences on flow pattern and pollutant distribution in an urban canyon. A large single clockwise vortex is generated in the canyon for the vaulted upstream roof at Z H /H = 1/6, 1/3, and 1/2, the trapezoidal and downward wedged roofs at Z H /H = 1/6 and 1/3, and the slanted and upward wedged roofs at Z H /H = 1/6, while a main clockwise vortex and a secondary counterclockwise vortex are established for the trapezoidal and downward wedged roofs at Z H /H = 1/2 and the slanted and upward wedged roofs at Z H /H = 1/3 and 1/2. In the one-vortex flow regime, the clockwise vortex moves upward and grows in size with increasing upstream roof height for the vaulted, trapezoidal, and downward wedged roofs. In the two-vortex flow regime, the size and rotational velocity of both upper clockwise and lower counterclockwise vortices increase with the upstream roof height for the slanted and upward wedged roofs. At Z H /H = 1/6, the pollution levels in the canyon are close among all the upstream roof shapes studied. At Z H /H = 1/3, the pollution levels in the canyon for the upward wedged roof and slanted roof are much higher than those for the vaulted, trapezoidal, and downward wedged roofs. At Z H /H = 1/2, the lowest pollution level appears in the canyon for the vaulted upstream roof, while the highest pollution level occurs in the canyon for the upward wedged roof.

Craniotomy - slideshow

MedlinePlus

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Evaluation of contralateral breast skin doses by thermoluminescent dosimeters of patients receiving adjuvant radiotherapy for breast cancer.

PubMed

Gorken, I B; Kentli, S; Alanyali, H; Karagüler, Z; Kinay, M

2002-01-01

It is reported that low dose radiation received by the contralateral breast (CLB) during adjuvant radiotherapy (RT) is carcinogenic. This trial was planned to evaluate the CLB skin doses received during adjuvant RT of breast carcinoma. Twenty-four breast carcinoma patients treated locally or locoregionally with adjuvant RT were included. RT was performed with only tangential fields (TA) in 6 patients whereas 9 patients had an extra internal mammary (IM) field (TAIM). The remaining 9 patients received 5-field locoregional RT (5FLR). All patients were treated with wedge filters except for 3 TA patients. Of 9 5FLR patients IM fields were treated with Co60 in 5 and with electrons in the remaining 4 patients. LiF(2)-based Ribbon type thermoluminescent dosimeters (TLD) were used for dose evaluation. An average of 10 TLD's, placed with 1 cm gaps beginning from the medial border of the treatment field along the central axis were used to obtain dose measurements. Median measure of TLD's between 2-8 cm and maximum dose point (MDP) values in the same range were used to evaluate the CLB dose. In TA patients the CLB skin received 6.3% of the total dose in patients treated with wedge filters and 7.13% with half-beam blocks. For 6 TAIM patients with IM fields treated with Co60, the CLB dose was 7.24%. In 5 of 9 5FLR patients, whose IM fields were treated with Co60 the CLB skin received 8.8% of the total dose, while for electron beam therapy the CLB dose was 5.44%. CLB median MDP values were as follows: 12.76% in TA patients treated with wedge filters and 11.45% with half-beam blocking; 11.89% in TAIM patients with IM fields treated with Co60 and 7.83% with electron beams; 12.29% in 5FLR patients of whose IM fields were treated with Co60 and 8.94% with electron beams. When compared to wedge filters, halfbeam blocks caused 13% increase in CLB doses. If IM fields were added, 27.5% and 62% increases at CLB doses were established with Co60 when compared to electron beam RT in 3-field and 5-field treatments, respectively. CLB doses increased by 15-40% with the increased number of treatment fields. MDP values were also found to be higher with IM fields treated with Co60, but the number of treatment fields and accessories used seemed to have no effect on MDP doses. We conclude that by using wedge filters instead of half-beam blocks and by increasing the number of fractions treated with electron energies for IM fields, apparent decreases in CLB doses can be obtained. Large number of cases is needed to statistically establish the significant differences between subgroups.

Microorganisms Trapped Within Permafrost Ice In The Fox Permafrost Tunnel, Alaska

NASA Astrophysics Data System (ADS)

Katayama, T.; Tanaka, M.; Douglas, T. A.; Cai, Y.; Tomita, F.; Asano, K.; Fukuda, M.

2008-12-01

Several different types of massive ice are common in permafrost. Ice wedges are easily recognized by their shape and foliated structure. They grow syngenetically or epigenetically as a result of repeated cycles of frost cracking followed by the infiltration of snow, melt water, soil or other material into the open frost cracks. Material incorporated into ice wedges becomes frozen and preserved. Pool ice, another massive ice type, is formed by the freezing of water resting on top of frozen thermokarst sediment or melting wedges and is not foliated. The Fox Permafrost Tunnel in Fairbanks was excavated within the discontinuous permafrost zone of central Alaska and it contains permafrost, ice wedges, and pool ice preserved at roughly -3°C. We collected samples from five ice wedges and three pool ice structures in the Fox Permafrost Tunnel. If the microorganisms were incorporated into the ice during its formation, a community analysis of the microorganisms could elucidate the environment in which the ice was formed. Organic material from sediments in the tunnel was radiocarbon-dated between 14,000 and 30,000 years BP. However, it is still not clear when the ice wedges were formed or subsequently deformed because they are only partially exposed and their upper surfaces are above the tunnel walls. The objectives of our study were to determine the biogeochemical conditions during massive ice formation and to analyze the microbial community within the ices by incubation-based and DNA-based analyses. The geochemical profile and the PCR-DGGE band patterns of bacteria among five ice wedge and 3 portions of pool ice samples were markedly different. The DGGE band patterns of fungi were simple with a few bands of fungi or yeast. The dominant bands of ice wedge and pool ice samples were affiliated with the genus Geomyces and Doratomyces, respectively. Phylogenetic analysis using rRNA gene ITS regions indicated isolates of Geomyces spp. from different ice wedges were affiliated with different clusters. The enumeration of fungal colonies among the ice wedge and pool ice samples were also different. These results demonstrate that different massive ice structures had different microbial and geochemical environments or backgrounds when they were formed.

The development and investigation of a prototype three-dimensional compensator for whole brain radiation therapy

NASA Astrophysics Data System (ADS)

Keall, Paul; Arief, Isti; Shamas, Sofia; Weiss, Elisabeth; Castle, Steven

2008-05-01

Whole brain radiation therapy (WBRT) is the standard treatment for patients with brain metastases, and is often used in conjunction with stereotactic radiotherapy for patients with a limited number of brain metastases, as well as prophylactic cranial irradiation. The use of open fields (conventionally used for WBRT) leads to higher doses to the brain periphery if dose is prescribed to the brain center at the largest lateral radius. These dose variations potentially compromise treatment efficacy and translate to increased side effects. The goal of this research was to design and construct a 3D 'brain wedge' to compensate dose heterogeneities in WBRT. Radiation transport theory was invoked to calculate the desired shape of a wedge to achieve a uniform dose distribution at the sagittal plane for an ellipsoid irradiated medium. The calculations yielded a smooth 3D wedge design to account for the missing tissue at the peripheral areas of the brain. A wedge was machined based on the calculation results. Three ellipsoid phantoms, spanning the mean and ± two standard deviations from the mean cranial dimensions were constructed, representing 95% of the adult population. Film was placed at the sagittal plane for each of the three phantoms and irradiated with 6 MV photons, with the wedge in place. Sagittal plane isodose plots for the three phantoms demonstrated the feasibility of this wedge to create a homogeneous distribution with similar results observed for the three phantom sizes, indicating that a single wedge may be sufficient to cover 95% of the adult population. The sagittal dose is a reasonable estimate of the off-axis dose for whole brain radiation therapy. Comparing the dose with and without the wedge the average minimum dose was higher (90% versus 86%), the maximum dose was lower (107% versus 113%) and the dose variation was lower (one standard deviation 2.7% versus 4.6%). In summary, a simple and effective 3D wedge for whole brain radiotherapy has been developed. The wedge gives a more uniform dose distribution than commonly used techniques. Further development and shape optimization may be necessary prior to clinical implementation.

Evidence for Patchy Sediment Underthrusting and a Strong, Drained Outer Accretionary Wedge in Central Cascadia: Implications for Dynamic Slip Conditions

NASA Astrophysics Data System (ADS)

Tobin, H. J.; Webb, S. I.

2017-12-01

The central Cascadia subduction zone forearc in the region offshore Washington, where a hot, young incoming plate is covered by a 2-3 km thick sedimentary sequence, features a wide, very narrowly-tapered outer accretionary wedge composed of landward vergent thrust sheets. Longstanding questions for this region include the position and host-rock environment of the plate boundary décollement fault, the thickness of sedimentary strata underthrust beneath the wedge with the downgoing plate, and the effective stress or pore fluid pressure condition in the wedge and along its base. We have analyzed nine multichannel seismic lines of the 2012 COAST multi-channel seismic reflection survey using both time- and depth- migrated seismic sections for structural interpretation. Results show that there is evidence for two parallel décollement levels, with up to 200 - 500 meters thickness of a mostly-underthrust sequence in places, but which is absent entirely in others. This patchy distribution is mapped and related to features of the overlying wedge structure. We also analyzed the seismic interval velocity distribution produced during pre-stack depth migration imaging, and used it to compute estimated porosity, pore fluid pressure, and effective stress via empirical physical properties transforms. We find that the wedge shows evidence for at most only modest, localized excess pore pressure, and instead most of the wedge appears to be at near-hydrostatic, drained condition. Modest overpressure ratios of up to only 0.15 are detected, localized in the footwalls of thrust splays. We find no evidence for overpressure zones in the underthrust sequence below the upper décollement, in contrast to findings from several other wedges worldwide. Taken together, the accretionary wedge structure and apparent low pore pressure condition here is consistent with a mechanically strong wedge overlying a base that is very weak, at least transiently. By analogy with recent work from Sumatra, Tohoku, and elsewhere, we speculate that this is potentially conducive to efficient propagation of megathrust slip to the deformation front in large earthquakes.

SU-E-T-362: Enhanced Dynamic Wedge Output Factors for Varian 2300CD and the Case for a Reference Database

DOE Office of Scientific and Technical Information (OSTI.GOV)

Njeh, C

2015-06-15

Purpose: Dose inhomogeneity in treatment planning can be compensated using physical wedges. Enhanced dynamic wedges (EDW) were introduced by Varian to overcome some of the short comings of physical wedges. The objectives of this study were to measure EDW output factors for 6 MV and 20 MV photon energies for a Varian 2300CD. Secondly to review the literature in terms of published enhanced dynamic wedge output factors (EDWOF) for different Varian models and thereby adding credence to the case of the validity of reference databases. Methods: The enhanced dynamic wedge output factors were measured for the Varian 2300CD for bothmore » 6 MV and 20 MV photon energies. Twelve papers with published EDWOF for different Varian Linac models were found in the literature. Results: The EDWOF for 6 MV varied from 0.980 for a 5×5 cm 10 degree wedge to 0.424 for 20×20 cm 60 degree wedge. Similarly for 20 MV, the EDWOF varied from 0.986 for 5×5 cm 10 degree wedge to 0.529 for 20×20 cm 60 degree wedge. EDWOF are highly dependent on field size. Comparing our results with the published mean, we found an excellent agreement for 6 MV EDWOF with the percentage differences ranging from 0.01% to 0.57% with a mean of 0.03%. The coefficient of variation of published EDWOF ranged from 0.17% to 0.85% and 0.1% to 0.9% for the for 6 MV and 18MV photon energies respectively. This paper provides the first published EDWOF for 20 MV photon energy. In addition, we have provided the first compendium of EDWOFs for different Varian linac models. Conclusion: The consistency of EDWOF across models and institution provide further support that, a standard data set of basic photon and electron dosimetry could be established, as a guide for future commissioning, beam modeling and quality assurance purposes.« less

SU-E-T-562: Scanned Percent Depth Dose Curve Discrepancy for Photon Beams with Physical Wedge in Place (Varian IX) Using Different Sensitive Volume Ion Chambers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, H; Sarkar, V; Rassiah-Szegedi, P

2014-06-01

Purpose: To investigate and report the discrepancy of scanned percent depth dose (PDD) for photon beams with physical wedge in place when using ion chambers with different sensitive volumes. Methods/Materials: PDD curves of open fields and physical wedged fields (15, 30, 45, and 60 degree wedge) were scanned for photon beams (6MV and 10MV, Varian iX) with field size of 5x5 and 10x10 cm using three common scanning chambers with different sensitive volumes - PTW30013 (0.6cm3), PTW23323 (0.1cm3) and Exradin A16 (0.007cm3). The scanning system software used was OmniPro version 6.2, and the scanning water tank was the Scanditronix Wellhoffermore » RFA 300.The PDD curves from the three chambers were compared. Results: Scanned PDD curves of the same energy beams for open fields were almost identical between three chambers, but the wedged fields showed non-trivial differences. The largest differences were observed between chamber PTW30013 and Exradin A16. The differences increased as physical wedge angle increased. The differences also increased with depth, and were more pronounced for 6MV beam. Similar patterns were shown for both 5x5 and 10x10 cm field sizes. For open fields, all PDD values agreed with each other within 1% at 10cm depth and within 1.62% at 20 cm depth. For wedged fields, the difference of PDD values between PTW30013 and A16 reached 4.09% at 10cm depth, and 5.97% at 20 cm depth for 6MV with 60 degree physical wedge. Conclusion: We observed a significant difference in scanned PDD curves of photon beams with physical wedge in place obtained when using different sensitive volume ion chambers. The PDD curves scanned with the smallest sensitive volume ion chamber showed significant difference from larger chamber results, beyond 10cm depth. We believe this to be caused by varying response to beam hardening by the wedges.« less

Monoplanar versus biplanar medial open-wedge proximal tibial osteotomy for varus gonarthrosis: a comparison of clinical and radiological outcomes.

PubMed

Elmalı, Nurzat; Esenkaya, Irfan; Can, Murat; Karakaplan, Mustafa

2013-12-01

We compared clinical and radiological results of two proximal tibial osteotomy (PTO) techniques: monoplanar medial open-wedge osteotomy and biplanar retrotubercle medial open-wedge osteotomy, stabilised by a wedged plate. We evaluated 88 knees in 78 patients. Monoplanar medial open-wedge PTO was performed on 56 knees in 50 patients with a mean age of 55 ± 9 years. Biplanar retrotubercle medial open-wedge PTO was performed on 32 knees in 28 patients with a mean age of 57 ± 7 years. Mean follow-up periods were 40.6 ± 7 months for the monoplanar PTO group and 38 ± 5 months for the biplanar retrotubercle PTO group. Clinical outcome was evaluated using the hospital for special surgery scoring system, and radiological outcome was evaluated by the measurements of femorotibial angle (FTA), patellar height and tibial slope changes. In both groups, post-operative HSS scores increased significantly. No significant difference was found between groups in FTA alteration, but the FTA decreased significantly in both groups. Patellar index ratios decreased significantly in the monoplanar PTO group (Insall-Salvati Index by 0.07, Blackburne-Peel Index by 0.07), but not in the biplanar retrotubercle PTO group. Tibial slopes were increased significantly in the monoplanar PTO group, but not in the retrotubercle PTO group. Biplanar retrotubercle medial open-wedge osteotomy and monoplanar medial open-wedge osteotomy are both clinically effective for the treatment for varus gonarthrosis. Retrotubercle osteotomy also prevents patella infera and tibial slope changes radiologically.

Assessment of Neutron Contamination Originating from the Presence of Wedge and Block in Photon Beam Radiotherapy.

PubMed

Bahreyni Toossi, M T; Khajetash, B; Ghorbani, M

2018-03-01

One of the main causes of induction of secondary cancer in radiation therapy is neutron contamination received by patients during treatment. Objective: In the present study the impact of wedge and block on neutron contamination production is investigated. The evaluations are conducted for a 15 MV Siemens Primus linear accelerator. Simulations were performed using MCNPX Monte Carlo code. 30˚, 45˚ and 60˚ wedges and a cerrobend block with dimensions of 1.5 × 1.5 × 7 cm 3 were simulated. The investigation were performed in the 10 × 10 cm 2 field size at source to surface distance of 100 cm for depth of 0.5, 2, 3 and 4 cm in a water phantom. Neutron dose was calculated using F4 tally with flux to dose conversion factors and F6 tally. Results showed that the presence of wedge increases the neutron contamination when the wedge factor was considered. In addition, 45˚ wedge produced the most amount of neutron contamination. If the block is in the center of the field, the cerrobend block caused less neutron contamination than the open field due to absorption of neutrons and photon attenuation. The results showed that neutron contamination is less in steeper depths. The results for two tallies showed practically equivalent results. Wedge causes neutron contamination hence should be considered in therapeutic protocols in which wedge is used. In terms of clinical aspects, the results of this study show that superficial tissues such as skin will tolerate more neutron contamination than the deep tissues.

Aligning Optical Fibers by Means of Actuated MEMS Wedges

NASA Technical Reports Server (NTRS)

Morgan, Brian; Ghodssi, Reza

2007-01-01

Microelectromechanical systems (MEMS) of a proposed type would be designed and fabricated to effect lateral and vertical alignment of optical fibers with respect to optical, electro-optical, optoelectronic, and/or photonic devices on integrated circuit chips and similar monolithic device structures. A MEMS device of this type would consist of a pair of oppositely sloped alignment wedges attached to linear actuators that would translate the wedges in the plane of a substrate, causing an optical fiber in contact with the sloping wedge surfaces to undergo various displacements parallel and perpendicular to the plane. In making it possible to accurately align optical fibers individually during the packaging stages of fabrication of the affected devices, this MEMS device would also make it possible to relax tolerances in other stages of fabrication, thereby potentially reducing costs and increasing yields. In a typical system according to the proposal (see Figure 1), one or more pair(s) of alignment wedges would be positioned to create a V groove in which an optical fiber would rest. The fiber would be clamped at a suitable distance from the wedges to create a cantilever with a slight bend to push the free end of the fiber gently to the bottom of the V groove. The wedges would be translated in the substrate plane by amounts Dx1 and Dx2, respectively, which would be chosen to move the fiber parallel to the plane by a desired amount Dx and perpendicular to the plane by a desired amount Dy. The actuators used to translate the wedges could be variants of electrostatic or thermal actuators that are common in MEMS.

Capillary Rise in a Wedge

ERIC Educational Resources Information Center

Piva, M.

2009-01-01

In introductory-level physics courses, the concept of surface tension is often illustrated using the example of capillary rise in thin tubes. In this paper the author describes experiments conducted using a planar geometry created with two small plates forming a thin wedge. The distribution of the fluid entering the wedge can be studied as a…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalantar, D.

This document provides information on the distribution of unconverted light in the National Ignition Facility (NIF) target chamber with the wedged final focus lens that has been adopted by the NIF project. It includes a comparison of the wedged lens configuration with the color separation grating (CSG). There are significant benefits to the wedged lens design as it greatly simplifies experiment design.

Impingement of water droplets on wedges and double-wedge airfoils at supersonic speeds

NASA Technical Reports Server (NTRS)

Serafini, John S

1954-01-01

An analytical solution has been obtained for the equations of motion of water droplets impinging on a wedge in a two-dimensional supersonic flow field with a shock wave attached to the wedge. The closed-form solution yields analytical expressions for the equation of the droplet trajectory, the local rate of impingement and the impingement velocity at any point on the wedge surface, and the total rate of impingement. The analytical expressions are utilized to determine the impingement on the forward surfaces of diamond airfoils in supersonic flow fields with attached shock waves. The results presented include the following conditions: droplet diameters from 2 to 100 microns, pressure altitudes from sea level to 30,000 feet, free-stream static temperatures from 420 degrees r, free stream Mach numbers from 1.1 to 2.0, semiapex angles for the wedge from 1.14 degrees to 7.97 degrees, thickness-to-chord ratios for the diamond airfoil from 0.02 to 0.14, chord lengths from 1 to 20 feet, and angles of attack from zero to the inverse tangent of the airfoil thickness-to-chord ratio.

The crack and wedging problem for an orthotropic strip

NASA Technical Reports Server (NTRS)

Cinar, A.; Erdogan, F.

1983-01-01

The plane elasticity problem for an orthotropic strip containing a crack parallel to its boundaries is considered. The problem is formulated under general mixed mode loading conditions. The stress intensity factors depend on two dimensionless orthotropic constants only. For the crack problem the results are given for a single crack and two collinear cracks. The calculated results show that of the two orthotropic constants the influence of the stiffness ratio on the stress intensity factors is much more significant than that of the shear parameter. The problem of loading the strip by a rigid rectangular lengths continuous contact is maintained along the wedge strip interface; at a certain critical wedge length the separation starts at the midsection of the wedge, and the length of the separation zone increases rapidly with increasing wedge length. Previously announced in STAR as N82-26707

Split-field pupil plane determination apparatus

DOEpatents

Salmon, Joseph T.

1996-01-01

A split-field pupil plane determination apparatus (10) having a wedge assembly (16) with a first glass wedge (18) and a second glass wedge (20) positioned to divide a laser beam (12) into a first laser beam half (22) and a second laser beam half (24) which diverge away from the wedge assembly (16). A wire mask (26) is positioned immediately after the wedge assembly (16) in the path of the laser beam halves (22, 24) such that a shadow thereof is cast as a first shadow half (30) and a second shadow half (32) at the input to a relay telescope (14). The relay telescope (14) causes the laser beam halves (22, 24) to converge such that the first shadow half (30) of the wire mask (26) is aligned with the second shadow half (32) at any subsequent pupil plane (34).

Designing a pain management protocol for craniotomy: A narrative review and consideration of promising practices

PubMed Central

Vacas, Susana; Van de Wiele, Barbara

2017-01-01

Background: Craniotomy is a relatively common surgical procedure with a high incidence of postoperative pain. Development of standardized pain management and enhanced recovery after surgery (ERAS) protocols are necessary and crucial to optimize outcomes and patient satisfaction and reduce health care costs. Methods: This work is based upon a literature search of published manuscripts (between 1996 and 2017) from Pubmed, Cochrane Central Register, and Google Scholar. It seeks to both synthesize and review our current scientific understanding of postcraniotomy pain and its part in neurosurgical ERAS protocols. Results: Strategies to ameliorate craniotomy pain demand interventions during all phases of patient care: preoperative, intraoperative, and postoperative interventions. Pain management should begin in the perioperative period with risk assessment, patient education, and premedication. In the intraoperative period, modifications in anesthesia technique, choice of opioids, acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs), regional techniques, dexmedetomidine, ketamine, lidocaine, corticosteroids, and interdisciplinary communication are all strategies to consider and possibly deploy. Opioids remain the mainstay for pain relief, but patient-controlled analgesia, NSAIDs, standardization of pain management, bio/behavioral interventions, modification of head dressings as well as patient-centric management are useful opportunities that potentially improve patient care. Conclusions: Future research on mechanisms, predictors, treatments, and pain management pathways will help define the combinations of interventions that optimize pain outcomes. PMID:29285407

Preferences and Utilities for Health States after Treatment of Olfactory Groove Meningioma: Endoscopic versus Open.

PubMed

Yao, Christopher M; Kahane, Alyssa; Monteiro, Eric; Gentili, Fred; Zadeh, Gelareh; de Almeida, John R

2017-08-01

Objectives  The purpose of this study is to report health utility scores for patients with olfactory groove meningiomas (OGM) treated with either the standard transcranial approach, or the expanded endonasal endoscopic approach. Design  The time trade-off technique was used to derive health utility scores. Setting  Healthy individuals without skull base tumors were surveyed. Main Outcome Measures  Participants reviewed and rated scenarios describing treatment (endoscopic, open, stereotactic radiation, watchful waiting), remission, recurrence, and complications associated with the management of OGMs. Results  There were 51 participants. The endoscopic approach was associated with higher utility scores compared with an open craniotomy approach (0.88 vs. 0.74; p  < 0.001) and watchful waiting (0.88 vs.0.74; p  = 0.002). If recurrence occurred, revision endoscopic resection continued to have a higher utility score compared with revision open craniotomy (0.68; p  = 0.008). On multivariate analysis, older individuals were more likely to opt for watchful waiting ( p  = 0.001), whereas participants from higher income brackets were more likely to rate stereotactic radiosurgery with higher utility scores ( p  = 0.017). Conclusion  The endoscopic approach was associated with higher utility scores than craniotomy for primary and revision cases. The present utilities can be used for future cost-utility analyses.

Distal Femoral Osteotomy for the Valgus Knee: Medial Closing Wedge Versus Lateral Opening Wedge: A Systematic Review.

PubMed

Wylie, James D; Jones, Daniel L; Hartley, Melissa K; Kapron, Ashley L; Krych, Aaron J; Aoki, Stephen K; Maak, Travis G

2016-10-01

(1) To determine the radiographic correction/healing rate, patient-reported outcomes, reoperation rate, and complication rate after distal femoral osteotomy (DFO) for the valgus knee with lateral compartment pathology. (2) To summarize the reported results of medial closing wedge and lateral opening wedge DFO. We conducted a systematic review of PubMed, MEDLINE, and CINAHL to identify studies reporting outcomes of DFOs for the valgus knee. Keywords included "distal femoral osteotomy," "chondral," "cartilage," "valgus," "joint restoration," "joint preservation," "arthritis," and "gonarthrosis." Two authors first reviewed the articles; our study exclusion criteria were then applied, and the articles were included on the basis relevance defined by the aforementioned criteria. The Methodological Index for Nonrandomized Studies scale judged the quality of the literature. Sixteen studies were relevant to the research questions out of 191 studies identified by the original search. Sixteen studies were identified reporting on 372 osteotomies with mean follow-up of 45 to 180 months. All studies reported mean radiographic correction to a near neutral mechanical axis, with 3.2% nonunion and 3.8% delayed union rates. There was a 9% complication rate and a 34% reoperation rate, of which 15% were converted to arthroplasty. There were similar results reported for medial closing wedge and lateral opening wedge techniques, with a higher conversion to arthroplasty in the medial closing wedge that was confounded by longer mean follow-up in this group (mean follow-up 100 v 58 months). DFOs for the valgus knee with lateral compartment disease provide improvements in patient-reported knee health-related quality of life at midterm follow-up but have high rates of reoperation. No evidence exists proving better results of either the lateral opening wedge or medial closing wedge techniques. Level IV, systematic review of Level IV studies. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

SU-E-T-82: A Study On Enhanced Dynamic Wedge (EDW) Dosimetry Using 2D Seven29 Ion Chamber Array Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Syam; Aparna

2015-06-15

Purpose: To study the dosimetric properties of Enhanced Dynamic Wedge (EDW) using PTW Seven29 ion chamber array Methods: PTW Seven29 ion chamber array and Solid Water phantoms for different depths were used for the study. The study was carried out in Varian Clinac ix with photon energies, 6MV & 15MV. Primarily the solid water phantoms with the 2D array were scanned using a CT scanner (GE Optima 580) at different depths. These scanned images were used for EDW planning in an Eclipse treatment planning system (version 10). Planning was done for different wedge angles and for different depths for 6MVmore » & 15MV. A dose of 100 CGy was delivered in each cases. For each delivery, calculated the Monitoring Unit (MU) required. Same set-up was created before delivering the plans in Varian Clinac-ix. For each clinically relevant depth and for different wedge angles, the same MU was delivered as calculated. Different wedged dose distributions where reconstructed from the measured 2D array data using the in-house developed excel program. Results: It is observed that the shoulder like region in the profile which reduces as depth increases. For the same depth and energy, the percentage difference between planned and measured dose is lesser than 3%. For smaller wedge angles, the percentage difference is found to be greater than 3% for the largest wedge angle. Standard deviation between measured doses at shoulder region for planned and measured profiles is 0.08 and 0.02 respectively. Standard deviations between planned and measured wedge factors for different depths (2.5cm, 5cm, 10cm, and 15cm) are (0.0021, 0.0007, 0.0050, 0.0001) for 6MV and (0.0024, 0.0191, 0.0013, 0.0005) for 15MV respectively. Conclusion: The 2D Seven29 ion chamber array is a good tool for the Enhanced Dynamic Wedge (EDW) dosimetry.« less

Fracture and contact problems for an elastic wedge

NASA Technical Reports Server (NTRS)

Erdogan, F.; Arin, K.

1974-01-01

The plane elastostatic contact problem for an infinite elastic wedge of arbitrary angle is discussed. The medium is loaded through a frictionless rigid wedge of a given symmetric profile. Using the Mellin transform formulation the mixed boundary value problem is reduced to a singular integral equation with the contact stress as the unknown function. With the application of the results to the fracture of the medium in mind, the main emphasis in the study has been on the investigation of the singular nature of the stress state around the apex of the wedge and on the determination of the contact pressure.

Fracture and contact problems for an elastic wedge

NASA Technical Reports Server (NTRS)

Erdogan, F.; Arin, K.

1976-01-01

The paper deals with the plane elastostatic contact problem for an infinite elastic wedge of arbitrary angle. The medium is loaded through a frictionless rigid wedge of a given symmetric profile. Using the Mellin transform formulation the mixed boundary value problem is reduced to a singular integral equation with the contact stress as the unknown function. With the application of the results to the fracture of the medium in mind, the main emphasis in the study has been on the investigation of the singular nature of the stress state around the apex of the wedge and on the determination of the contact pressure.

Severe winter cooling during the Younger Dryas in northern Alaska - evidence from the stable isotope composition of a buried ice-wedge system

NASA Astrophysics Data System (ADS)

Meyer, Hanno; Schirrmeister, Lutz; Yoshikawa, Kenji; Opel, Thomas; Wetterich, Sebastian; Hubberten, Hans-W.; Brown, Jerry

2010-05-01

The Younger Dryas (YD) interval, from approximately 12.9 to 11.5 kyr cal BP, a rapid reversion to glacial climate conditions at the Pleistocene-Holocene transition, has generally been attributed to the release of meltwater from the Laurentide Ice Sheet to the North Atlantic or Arctic oceans. The reaction of the North Pacific region to this "shutdown" of the thermohaline circulation in the North Atlantic during Younger Dryas is, however, little understood. The YD cold interval is of great interest for understanding rapid natural climate change, especially with regard to recent global warming scenarios. Various archives such as glacier ice, tree rings, lacustrine and marine sediments provide evidence for strong climate variability during the Late Glacial-Holocene transition. In our study, we investigated a relict, buried ice-wedge system within the continuous permafrost zone near Barrow, northern Alaska (71°18'N, 156°40'W). The Barrow ice-wedge system is buried under about three meters of Late Glacial/early Holocene ice-rich sediments. The ice wedges are accessible through a shaft which extends into an underground excavation, where a detailed description and sampling with an electrical chain saw were carried out. Permafrost is not only susceptible to recent climate change, it also may store evidence of these changes in ground ice, especially in ice wedges. Ice wedges can be assessed by stable water isotope methods similar to glacier ice climate reconstructions. Ice wedges are assumed to be indicative of winter climate conditions, because the seasonality of thermal contraction cracking and of the infill of frost cracks are generally related to winter and spring, respectively. In this paper, we present a winter climate record from ice wedges in permafrost of northern Alaska, a region, where paleoclimate records extending beyond the Late Glacial-Holocene transition are generally rather sparse, often restricted to lake sediments and rely mostly on summer indicators such as pollen. This reconstruction is the first radiocarbon-dated centennial-scale stable water isotope record from permafrost at all. The Late Glacial winter climate reconstruction from Barrow ice wedges clearly demonstrates the existence of a Younger Dryas cold event, formerly believed to be reduced or absent in this area. Comparing the Barrow ice-wedge record to Greenland ice cores (such as N-GRIP), we observe similar and contemporaneous isotopic variations in the same order of magnitude, underpinning the climatic relevance of our ice wedge data. The Barrow ice-wedge stable isotope record additionally displays a gradual change of the atmospheric moisture source conditions during the Younger Dryas reflected in a shift of the d excess, potentially being associated with the successive opening of the Bering Strait.

An IBEM solution to the scattering of plane SH-waves by a lined tunnel in elastic wedge space

NASA Astrophysics Data System (ADS)

Liu, Zhongxian; Liu, Lei

2015-02-01

The indirect boundary element method (IBEM) is developed to solve the scattering of plane SH-waves by a lined tunnel in elastic wedge space. According to the theory of single-layer potential, the scattered-wave field can be constructed by applying virtual uniform loads on the surface of lined tunnel and the nearby wedge surface. The densities of virtual loads can be solved by establishing equations through the continuity conditions on the interface and zero-traction conditions on free surfaces. The total wave field is obtained by the superposition of free field and scattered-wave field in elastic wedge space. Numerical results indicate that the IBEM can solve the diffraction of elastic wave in elastic wedge space accurately and efficiently. The wave motion feature strongly depends on the wedge angle, the angle of incidence, incident frequency, the location of lined tunnel, and material parameters. The waves interference and amplification effect around the tunnel in wedge space is more significant, causing the dynamic stress concentration factor on rigid tunnel and the displacement amplitude of flexible tunnel up to 50.0 and 17.0, respectively, more than double that of the case of half-space. Hence, considerable attention should be paid to seismic resistant or anti-explosion design of the tunnel built on a slope or hillside.

Pain following Craniotomy: Reassessment of the Available Options

PubMed Central

Haldar, Rudrashish; Kaushal, Ashutosh; Gupta, Devendra; Srivastava, Shashi; Singh, Prabhat K.

2015-01-01

Pain following craniotomy has frequently been neglected because of the notion that postcraniotomy patients do not experience severe pain. However a gradual change in this outlook is observed because of increased sensitivity of neuroanaesthesiologists and neurosurgeons toward acute postcraniotomy pain. Multiple modalities exist for treating this variety of pain each with its own share of advantages and disadvantages. However, individually none of these modalities has been proclaimed as the best and applicable universally. A considerable amount of dispute remains to ascertain the appropriate therapeutic regimen for treating postcraniotomy pain in spite of numerous trials using different drugs and their combinations. This review aims to highlight the genesis, characteristics, and different strategies that are undertaken for management of acute postcraniotomy pain. Chronic postcraniotomy pain which can be debilitating sequelae is also discussed concisely. PMID:26495298

Seismic reflection images of the accretionary wedge of Costa Rica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shipley, T.H.; Stoffa, P.L.; McIntosh, K.

The large-scale structure of modern accretionary wedges is known almost entirely from seismic reflection investigations using single or grids of two-dimensional profiles. The authors will report on the first three-dimensional seismic reflection data volume collected of a wedge. This data set covers a 9-km-wide {times} 22-km-long {times} 6-km-thick volume of the accretionary wedge just arcward of the Middle America Trench off Costa Rica. The three-dimensional processing has improved the imaging ability of the multichannel data, and the data volume allows mapping of structures from a few hundred meters to kilometers in size. These data illustrate the relationships between the basement,more » the wedge shape, and overlying slope sedimentary deposits. Reflections from within the wedge define the gross structural features and tectonic processes active along this particular convergent margin. So far, the analysis shows that the subdued basement relief (horst and graben structures seldom have relief of more than a few hundred meters off Costa Rica) does affect the larger scale through going structural features within the wedge. The distribution of mud volcanoes and amplitude anomalies associated with the large-scale wedge structures suggests that efficient fluid migration paths may extend from the top of the downgoing slab at the shelf edge out into the lower and middle slope region at a distance of 50-100 km. Offscraping of the uppermost (about 45 m) sediment occurs within 4 km of the trench, creating a small pile of sediments near the trench lower slope. Underplating of parts of the 400-m-thick subducted sedimentary section begins at a very shallow structural level, 4-10 km arcward of the trench. Volumetrically, the most important accretionary process is underplating.« less

Rainfall induced groundwater mound in wedge-shaped promontories: The Strack-Chernyshov model revisited

NASA Astrophysics Data System (ADS)

Kacimov, A. R.; Kayumov, I. R.; Al-Maktoumi, A.

2016-11-01

An analytical solution to the Poisson equation governing Strack's discharge potential (squared thickness of a saturated zone in an unconfined aquifer) is obtained in a wedge-shaped domain with given head boundary conditions on the wedge sides (specified water level in an open water body around a porous promontory). The discharge vector components, maximum elevation of the water table in promontory vertical cross-sections, quantity of groundwater seeping through segments of the wedge sides, the volume of fresh groundwater in the mound are found. For acute angles, the solution to the problem is non-unique and specification of the behaviour at infinity is needed. A ;basic; solution is distinguished, which minimizes the water table height above a horizontal bedrock. MODFLOW simulations are carried out in a finite triangular island and compare solutions with a constant-head, no-flow and ;basic; boundary condition on one side of the triangle. Far from the tip of an infinite-size promontory one has to be cautious with truncation of the simulated flow domains and imposing corresponding boundary conditions. For a right and obtuse wedge angles, there are no positive solutions for the case of constant accretion on the water table. In a particular case of a confined rigid wedge-shaped aquifer and incompressible fluid, from an explicit solution to the Laplace equation for the hydraulic head with arbitrary time-space varying boundary conditions along the promontory rays, essentially 2-D transient Darcian flows within the wedge are computed. They illustrate that surface water waves on the promontory boundaries can generate strong Darcian waves inside the porous wedge. Evaporation from the water table and sea-water intruded interface (rather than a horizontal bed) are straightforward generalizations for the Poissonian Strack potential.

Effect of Laterally Wedged Insoles on the External Knee Adduction Moment across Different Reference Frames.

PubMed

Yamaguchi, Satoshi; Kitamura, Masako; Ushikubo, Tomohiro; Murata, Atsushi; Akagi, Ryuichiro; Sasho, Takahisa

2015-01-01

Biomechanical effects of laterally wedged insoles are assessed by reduction in the knee adduction moment. However, the degree of reduction may vary depending on the reference frame with which it is calculated. The purpose of this study was to clarify the effect of reference frame on the reduction in the knee adduction moment by laterally wedged insoles. Twenty-nine healthy participants performed gait trials with a laterally wedged insole and with a flat insole as a control. The knee adduction moment, including the first and second peaks and the angular impulse, were calculated using four different reference frames: the femoral frame, tibial frame, laboratory frame and the Joint Coordinate System. There were significant effects of reference frame on the knee adduction moment first and second peaks (P < 0.001 for both variables), while the effect was not significant for the angular impulse (P = 0.84). No significant interaction between the gait condition and reference frame was found in either of the knee adduction moment variables (P = 0.99 for all variables), indicating that the effects of laterally wedged insole on the knee adduction moments were similar across the four reference frames. On the other hand, the average percent changes ranged from 9% to 16% for the first peak, from 16% to 18% for the second peak and from 17% to 21% for the angular impulse when using the different reference frames. The effects of laterally wedged insole on the reduction in the knee adduction moment were similar across the reference frames. On the other hand, Researchers need to recognize that when the percent change was used as the parameter of the efficacy of laterally wedged insole, the choice of reference frame may influence the interpretation of how laterally wedged insoles affect the knee adduction moment.

Stress singularities at the vertex of a cylindrically anisotropic wedge

NASA Technical Reports Server (NTRS)

Delale, F.; Erdogan, F.; Boduroglu, H.

1980-01-01

The plane elasticity problem for a cylindrically anisotropic solid is formulated. The form of the solution for an infinite wedge shaped domain with various homogeneous boundary conditions is derived and the nature of the stress singularity at the vertex of the wedge is studied. The characteristic equations giving the stress singularity and the angular distribution of the stresses around the vertex of the wedge are obtained for three standard homogeneous boundary conditions. The numerical examples show that the singular behavior of the stresses around the vertex of an anisotropic wedge may be significantly different from that of the isotropic material. Some of the results which may be of practical importance are that for a half plane the stress state at r = 0 may be singular and for a crack the power of stress singularity may be greater or less than 1/2.

Investigation of two-dimensional wedge exhaust nozzles for advanced aircraft

NASA Technical Reports Server (NTRS)

Maiden, D. L.; Petit, J. E.

1975-01-01

Two-dimensional wedge nozzle performance characteristics were investigated in a series of wind-tunnel tests. An isolated single-engine/nozzle model was used to study the effects of internal expansion area ratio, aftbody cowl boattail angle, and wedge length. An integrated twin-engine/nozzle model, tested with and without empenage surfaces, included cruise, acceleration, thrust vectoring and thrust reversing nozzle operating modes. Results indicate that the thrust-minus-aftbody drag performance of the twin two-dimensional nozzle integration is significantly higher, for speeds greater than Mach 0.8, than the performance achieved with twin axisymmetric nozzle installations. Significant jet-induced lift was obtained on an aft-mounted lifting surface using a cambered wedge center body to vector thrust. The thrust reversing capabilities of reverser panels installed on the two-dimensional wedge center body were very effective for static or in-flight operation.

ROSAT Observations of Solar Wind Charge Exchange with the Lunar Exosphere

NASA Technical Reports Server (NTRS)

Collier, Michael R.; Snowden, S. L.; Benna, M.; Carter, J. A.; Cravens, T. E.; Hills, H. Kent; Hodges, R. R.; Kuntz, K. D.; Porter, F. Scott; Read, A.;

Transition from regular to irregular reflection of cylindrical converging shock waves over convex obstacles

NASA Astrophysics Data System (ADS)

Vignati, F.; Guardone, A.

2017-11-01

An analytical model for the evolution of regular reflections of cylindrical converging shock waves over circular-arc obstacles is proposed. The model based on the new (local) parameter, the perceived wedge angle, which substitutes the (global) wedge angle of planar surfaces and accounts for the time-dependent curvature of both the shock and the obstacle at the reflection point, is introduced. The new model compares fairly well with numerical results. Results from numerical simulations of the regular to Mach transition—eventually occurring further downstream along the obstacle—point to the perceived wedge angle as the most significant parameter to identify regular to Mach transitions. Indeed, at the transition point, the value of the perceived wedge angle is between 39° and 42° for all investigated configurations, whereas, e.g., the absolute local wedge angle varies in between 10° and 45° in the same conditions.

Linking megathrust earthquakes to brittle deformation in a fossil accretionary complex

PubMed Central

Dielforder, Armin; Vollstaedt, Hauke; Vennemann, Torsten; Berger, Alfons; Herwegh, Marco

2015-01-01

Seismological data from recent subduction earthquakes suggest that megathrust earthquakes induce transient stress changes in the upper plate that shift accretionary wedges into an unstable state. These stress changes have, however, never been linked to geological structures preserved in fossil accretionary complexes. The importance of coseismically induced wedge failure has therefore remained largely elusive. Here we show that brittle faulting and vein formation in the palaeo-accretionary complex of the European Alps record stress changes generated by subduction-related earthquakes. Early veins formed at shallow levels by bedding-parallel shear during coseismic compression of the outer wedge. In contrast, subsequent vein formation occurred by normal faulting and extensional fracturing at deeper levels in response to coseismic extension of the inner wedge. Our study demonstrates how mineral veins can be used to reveal the dynamics of outer and inner wedges, which respond in opposite ways to megathrust earthquakes by compressional and extensional faulting, respectively. PMID:26105966

Electromagnetic pump stator core

DOEpatents

Fanning, A.W.; Olich, E.E.; Dahl, L.R.

1995-01-17

A stator core for supporting an electrical coil includes a plurality of groups of circumferentially abutting flat laminations which collectively form a bore and perimeter. A plurality of wedges are interposed between the groups, with each wedge having an inner edge and a thicker outer edge. The wedge outer edges abut adjacent ones of the groups to provide a continuous path around the perimeter. 21 figures.

Electromagnetic pump stator core

DOEpatents

Fanning, Alan W.; Olich, Eugene E.; Dahl, Leslie R.

1995-01-01

A stator core for supporting an electrical coil includes a plurality of groups of circumferentially abutting flat laminations which collectively form a bore and perimeter. A plurality of wedges are interposed between the groups, with each wedge having an inner edge and a thicker outer edge. The wedge outer edges abut adjacent ones of the groups to provide a continuous path around the perimeter.

BOMB STABILIZING STRUCTURE

DOEpatents

Kelley, J.L.; Runyan, C.E.

1963-12-10

A stabilizinig structure capable of minimizing deviations of a falling body such as a bomb from desired trajectory is described. The structure comprises a fin or shroud arrangement of double-wedge configuration, the feeding portion being of narrow wedge shape and the after portion being of a wider wedge shape. The structure provides a force component for keeping the body on essentially desired trajectory throughout its fall. (AEC)

Is Tongue Strength an Important Influence on Rate of Articulation in Diadochokinetic and Reading Tasks?

ERIC Educational Resources Information Center

Neel, Amy T.; Palmer, Phyllis M.

2012-01-01

Purpose: The purpose of this study was to assess the relationship between tongue strength and rate of articulation in 2 speech tasks, diadochokinetic rates and reading aloud, in healthy men and women between 20 and 78 years of age. Method: Diadochokinetic rates were measured for the syllables /p[wedge]/, /t[wedge]/, /k[wedge]/, and…

Refined numerical solution of the transonic flow past a wedge

NASA Technical Reports Server (NTRS)

Liang, S.-M.; Fung, K.-Y.

1985-01-01

A numerical procedure combining the ideas of solving a modified difference equation and of adaptive mesh refinement is introduced. The numerical solution on a fixed grid is improved by using better approximations of the truncation error computed from local subdomain grid refinements. This technique is used to obtain refined solutions of steady, inviscid, transonic flow past a wedge. The effects of truncation error on the pressure distribution, wave drag, sonic line, and shock position are investigated. By comparing the pressure drag on the wedge and wave drag due to the shocks, a supersonic-to-supersonic shock originating from the wedge shoulder is confirmed.

An inverted continental Moho and serpentinization of the forearc mantle.

PubMed

Bostock, M G; Hyndman, R D; Rondenay, S; Peacock, S M

2002-05-30

Volatiles that are transported by subducting lithospheric plates to depths greater than 100 km are thought to induce partial melting in the overlying mantle wedge, resulting in arc magmatism and the addition of significant quantities of material to the overlying lithosphere. Asthenospheric flow and upwelling within the wedge produce increased lithospheric temperatures in this back-arc region, but the forearc mantle (in the corner of the wedge) is thought to be significantly cooler. Here we explore the structure of the mantle wedge in the southern Cascadia subduction zone using scattered teleseismic waves recorded on a dense portable array of broadband seismometers. We find very low shear-wave velocities in the cold forearc mantle indicated by the exceptional occurrence of an 'inverted' continental Moho, which reverts to normal polarity seaward of the Cascade arc. This observation provides compelling evidence for a highly hydrated and serpentinized forearc region, consistent with thermal and petrological models of the forearc mantle wedge. This serpentinized material is thought to have low strength and may therefore control the down-dip rupture limit of great thrust earthquakes, as well as the nature of large-scale flow in the mantle wedge.

Investigation of turbulent wedges generated by different single surface roughness elements

NASA Astrophysics Data System (ADS)

Traphan, Dominik; Meinlschmidt, Peter; Lutz, Otto; Peinke, Joachim; Gülker, Gerd

2013-11-01

It is known that small faults on rotor blades of wind turbines can cause significant power loss. In order to better understand the governing physical effects, in this experimental study, the formation of a turbulent wedge over a flat plate induced by single surface roughness elements is under investigation. The experiments are performed at different ambient pressure gradients, thus allowing conclusions about the formation of a turbulent wedge over an airfoil. With respect to typical initial faults on operating airfoils, the roughness elements are modified in both size and shape (raised or recessed). None intrusive experimental methods, such as stereoscopic PIV and LDA, enable investigations based on temporally and spatially highly resolved velocity measurements. In this way, a spectral analysis of the turbulent boundary layer is performed and differences in coherent structures within the wedge are identified. These findings are correlated with global measurements of the wedge carried out by infrared thermography. This correlation aims to enable distinguishing the cause and main properties of a turbulent wedge by the easy applicable method of infrared thermography, which is of practical relevance in the field of condition monitoring of wind turbines.

Effect of Shockwave Curvature on Run Distance Observed with a Modified Wedge Test

NASA Astrophysics Data System (ADS)

Lee, Richard; Dorgan, Robert; Sutherland, Gerrit; Benedetta, Ashley; Milby, Christopher

2011-06-01

The effect of wave curvature on shock initiation in PBXN-110 was investigated using a modified wedge test configuration. Various thicknesses of PBXN-110 donor slabs were used to define the shockwave curvature introduced to wedge samples of the same explosive. The donor slabs were initiated with line-wave generators so that the introduced shock would be the same shape, magnitude and duration across the entire input surface of the wedge. The shock parameters were varied for a given donor thickness via different widths of PMMA spacers placed between the donor and the wedge. A framing camera was used to observe where initiation occurred along the face of the wedge. Initiation always occurred at the center of the shock front instead of the sides like that reported by others using a much smaller test format. Results were compared to CTH calculations to indicate if there were effects associated with highly curved shock fronts that could not be adequately predicted. The run distance predicted in CTH for a 50.8 mm thick donor slab (low curvature) compared favorably with experimental results. However, results from thinner donor slabs (higher curvature) indicate a more sensitive behavior than the simulations predicted.

Effect of shockwave curvature on run distance observed with a modified wedge test

NASA Astrophysics Data System (ADS)

Lee, Richard; Dorgan, Robert J.; Sutherland, Gerrit; Benedetta, Ashley; Milby, Christopher

2012-03-01

The effect of wave curvature on shock initiation in PBXN-110 was investigated using a modified wedge test configuration. Various widths of PBXN-110 donor slabs were used to define the shockwave curvature introduced to wedge samples of the same explosive. The donor slabs were initiated with line-wave generators so that the shock from the donor would be the same shape, magnitude and duration across the entire input surface of the wedge. The shock parameters were varied for a given donor with PMMA spacers placed between the donor and the wedge sample. A high-speed electronic framing camera was used to observe where initiation occurred along the face of the wedge. Initiation always occurred at the center of the shock front instead of along the sides like that reported by others using a much smaller test format. Results were compared to CTH calculations to indicate if there were effects associated with highly curved shock fronts that could not be adequately predicted. The run distance predicted in CTH for a 50.8 mm wide donor slab (low curvature) compared favorably with experimental results. However, results from thinner donor slabs (higher curvature) indicate a more sensitive behavior than the simulations predicted.

Pretest 3-D finite element modeling of the wedge pillar portion of the WIPP (Waste Isolation Pilot Plant) Geomechanical Evaluation (Room G) in situ experiment. [Waste Isolation Pilot Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Preece, D.S.

Pretest 3-D finite element calculations have been performed on the wedge pillar portion of the WIPP Geomechanical Evaluation Experiment. The wedge pillar separates two drifts that intersect at an angle of 7.5/sup 0/. Purpose of the experiment is to provide data on the creep behavior of the wedge and progressive failure at the tip. The first set of calculations utilized a symmetry plane on the center-line of the wedge which allowed treatment of the entire configuration by modeling half of the geometry. Two 3-D calculations in this first set were performed with different drift widths to study the influence ofmore » drift size on closure and maximum stress. A cross-section perpendicular to the wedge was also analyzed with 2-D finite element models and the results compared to the 3-D results. In another set of 3-D calculations both drifts were modeled but with less distance between the drifts and the outer boundaries. Results of these calculations are compared with results from the other calculations to better understand the influence of boundary conditions.« less

Changes in prescribed doses for the Seattle neutron therapy system

NASA Astrophysics Data System (ADS)

Popescu, A.

2008-06-01

From the beginning of the neutron therapy program at the University of Washington Medical Center, the neutron dose distribution in tissue has been calculated using an in-house treatment planning system called PRISM. In order to increase the accuracy of the absorbed dose calculations, two main improvements were made to the PRISM treatment planning system: (a) the algorithm was changed by the addition of an analytical expression of the central axis wedge factor dependence with field size and depth developed at UWMC. Older versions of the treatment-planning algorithm used a constant central axis wedge factor; (b) a complete newly commissioned set of measured data was introduced in the latest version of PRISM. The new version of the PRISM algorithm allowed for the use of the wedge profiles measured at different depths instead of one wedge profile measured at one depth. The comparison of the absorbed dose calculations using the old and the improved algorithm showed discrepancies mainly due to the missing central axis wedge factor dependence with field size and depth and due to the absence of the wedge profiles at depths different from 10 cm. This study concludes that the previously reported prescribed doses for neutron therapy should be changed.

Glass Microbeads in Analog Models of Thrust Wedges.

PubMed

D'Angelo, Taynara; Gomes, Caroline J S

2017-01-01

Glass microbeads are frequently used in analog physical modeling to simulate weak detachment zones but have been neglected in models of thrust wedges. Microbeads differ from quartz sand in grain shape and in low angle of internal friction. In this study, we compared the structural characteristics of microbeads and sand wedges. To obtain a better picture of their mechanical behavior, we determined the physical and frictional properties of microbeads using polarizing and scanning electron microscopy and ring-shear tests, respectively. We built shortening experiments with different basal frictions and measured the thickness, slope and length of the wedges and also the fault spacings. All the microbeads experiments revealed wedge geometries that were consistent with previous studies that have been performed with sand. However, the deformation features in the microbeads shortened over low to intermediate basal frictions were slightly different. Microbeads produced different fault geometries than sand as well as a different grain flow. In addition, they produced slip on minor faults, which was associated with distributed deformation and gave the microbeads wedges the appearance of disharmonic folds. We concluded that the glass microbeads may be used to simulate relatively competent rocks, like carbonates, which may be characterized by small-scale deformation features.

Application of a radiophotoluminescent glass dosimeter to nonreference condition dosimetry in the postal dose audit system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mizuno, Hideyuki, E-mail: h-mizuno@nirs.go.jp; Fukumura, Akifumi; Fukahori, Mai

Purpose: The purpose of this study was to obtain a set of correction factors of the radiophotoluminescent glass dosimeter (RGD) output for field size changes and wedge insertions. Methods: Several linear accelerators were used for irradiation of the RGDs. The field sizes were changed from 5 × 5 cm to 25 × 25 cm for 4, 6, 10, and 15 MV x-ray beams. The wedge angles were 15°, 30°, 45°, and 60°. In addition to physical wedge irradiation, nonphysical (dynamic/virtual) wedge irradiations were performed. Results: The obtained data were fitted with a single line for each energy, and correction factorsmore » were determined. Compared with ionization chamber outputs, the RGD outputs gradually increased with increasing field size, because of the higher RGD response to scattered low-energy photons. The output increase was about 1% per 10 cm increase in field size, with a slight difference dependent on the beam energy. For both physical and nonphysical wedged beam irradiation, there were no systematic trends in the RGD outputs, such as monotonic increase or decrease depending on the wedge angle change if the authors consider the uncertainty, which is approximately 0.6% for each set of measured points. Therefore, no correction factor was needed for all inserted wedges. Based on this work, postal dose audits using RGDs for the nonreference condition were initiated in 2010. The postal dose audit results between 2010 and 2012 were analyzed. The mean difference between the measured and stated doses was within 0.5% for all fields with field sizes between 5 × 5 cm and 25 × 25 cm and with wedge angles from 15° to 60°. The standard deviations (SDs) of the difference distribution were within the estimated uncertainty (1SD) except for the 25 × 25 cm field size data, which were not reliable because of poor statistics (n = 16). Conclusions: A set of RGD output correction factors was determined for field size changes and wedge insertions. The results obtained from recent postal dose audits were analyzed, and the mean differences between the measured and stated doses were within 0.5% for every field size and wedge angle. The SDs of the distribution were within the estimated uncertainty, except for one condition that was not reliable because of poor statistics.« less

Aneurysm in the brain

MedlinePlus

... ruptured: Clipping is done during open brain surgery (craniotomy) . Endovascular repair is most often done. It usually ... unit (ICU) Complete bed rest and activity restrictions Drainage of blood from the brain area (cerebral ventricular ...

Awake Craniotomy with Noninvasive Brain Mapping by 3-Tesla Functional Magnetic Resonance Imaging for Excision of Low-grade Glioma: A Case of a Young Patient from Pakistan.

PubMed

Aleem Bhatti, Atta Ul; Jakhrani, Nasir Khan; Parekh, Maria Adnan

2018-01-01

The past few years have seen increasing support for gross total resection in the management of low-grade gliomas (LGGs), with a greater extent of resection correlated with better overall survival, progression-free survival, and time to malignant transformation. There is consistent evidence in literature supporting extent of safe resection as a good prognostic indicator as well as positively affecting seizure control, symptomatic relief in pressure symptoms, and longer progression-free and total survival. The operative goal in most LGG cases is to maximize the extent of resection for these benefits while avoiding postoperative neurologic deficits. Several advanced invasive and noninvasive surgical techniques such as intraoperative magnetic resonance imaging (MRI), fluorescence-guided surgery, intraoperative functional pathway mapping, and neuronavigation have been developed in an attempt to better achieve maximal safe resection. We present a case of LGG in a young patient with a 5-year history of refractory seizures and gradual onset walking difficulty. Serial MRI brain scans revealed a progressive increase in right frontal tumor size with substantial edema and parafalcine herniation. Noninvasive brain mapping by functional MRI (fMRI) and sleep-awake-sleep type of anesthesia with endotracheal tube insertion was utilized during an awake craniotomy. Histopathology confirmed a Grade II oligodendroglioma, and genetic analysis revealed no codeletion at 1p/19q. Neurological improvement was remarkable in terms of immediate motor improvement, and the patient remained completely seizure free on a single antiepileptic drug. There is no radiologic or clinical evidence of recurrence 6 months postoperatively. This is the first published report of an awake craniotomy for LGG in Pakistan. The contemporary concept of supratotal resection in LGGs advocates generous functional resection even beyond MRI findings rather than mere excision of oncological boundaries. This relatively aggressive approach is only possible with an awake craniotomy, which ensures preservation of functional status and thus less postoperative morbidity and better outcomes. Noninvasive mapping for intracranial space-occupying lesions, including fMRI and blood-oxygen-level dependent (BOLD) imaging modality, is an essential tool in a resource-limited setting such as Pakistan.

The role of heterogeneous fluid pressures in the shape of critical-taper submarine wedges, with application to Barbados

NASA Astrophysics Data System (ADS)

Yeh, En-Chao; Suppe, John

2014-05-01

Some classic accretionary wedges such as Nankai trough and Barbados are mechanically heterogeneous based on their spatial variation in taper, showing inward decrease in surface slope α without covariation in detachment dip β. Possible sources of regional heterogeniety include variation in fluid pressure, density, cohesion and fault strength, which can be constrained by the seismic or borehole observable parameter, fluid-retention depth Z_FRD, below which compaction is strongly diminished. In particular the Hubbert-Rubey fluid-pressure weakening can be addressed as (1-lambda)~0.6Z_FRD/Z. We recast the heterogeneous critical-taper wedge theory of Dahlen (1990) in terms of the observable Z_FRD/H, where H is the detachment depth, which allows for real world applications. For example, seismic velocity and borehole data from the Barbados shows that the fluid-retention depth Z_FRD is approximately constant and Z_FRD/H decreases inward. This leads to a factor of four inward decreases in wedge strength, dominated by fluid pressure, with only a second-order role for density and cohesion. An inward decrease in wedge strength should by itself produce an increase in taper, therefore the observed decreasing taper must be dominated by decreasing fault strength mu_b* from 0.03 to 0.01. Static fluid-pressures along the detachment in equilibrium with the overlying wedge predict the observed wedge geometry well, given a constant intrinsic friction coefficient mu_b=0.15.

Unlocking the Secrets of the Mantle Wedge: New Insights Into Melt Generation Processes in Subduction Zones

NASA Astrophysics Data System (ADS)

Grove, T. L.

2007-05-01

Recent laboratory studies of the melting and crystallization behavior of mantle peridotite and subduction zone lavas have led to new insights into melting processes in island arc settings. Melting of the mantle wedge in the presence of H2O begins at much lower temperatures than previously thought. The solidus of mantle peridotite at 3 GPa is ~ 800 °C, which is 200 °C below previous estimates. At pressures greater than 2.4 GPa chlorite becomes a stable phase on the solidus and it remains stable until ~ 3.5 GPa. Therefore, melting over this pressure range occurs in the presence of chlorite, which contains ~ 12 wt. % H2O. Chlorite stabilized on the peridotite solidus by slab-derived H2O may be the ultimate source of H2O for subduction zone magmatism. Thus, chlorite could transport large amounts of H2O into the descending mantle wedge to depths where it can participate in melting to generate hydrous arc magmas. Our ability to identify primitive mantle melts at subduction zones has led to the following observations. 1) Primitive mantle melts show evidence of final equilibration at shallow depths near the mantle - crust boundary. 2) They contain variable amounts of dissolved H2O (up to 6 wt. %). 3) They record variable extents of melting (up to > 25 wt. %). To produce melts with such variable characteristics requires more than one melting process and requires consideration of a new type of melting called hydrous flux melting. Flux melting occurs when the H2O - rich melt initially produced on the solidus near the base of the mantle wedge ascends and continuously reacts with overlying hotter, shallower mantle. The mantle melts and magmatic H2O content is constantly diluted as the melt ascends and reacts with shallower, hotter mantle. Anhydrous mantle melts are also found in close temporal and spatial proximity to hydrous flux melts. These melts are extracted at similar depths near the top of the mantle wedge when mantle is advected up and into the wedge corner and melted by adiabatic decompression. In light of these new insights into the chemical processes that lead to melt generation in subduction zones, further study of the influence of mantle dynamics and physical processes on melting is crucial. Variations in mantle permeability near the base of the wedge may exercise important controls on the access of fluids and/or melts to the overlying wedge. The presence of chlorite in the wedge may also influence rheological properties and seismicity in the vicinity of the slab - wedge interface. Improved knowledge of rheology and permeability will help us to develop more robust models of mantle flow and temperature distribution in the mantle wedge. These are crucial for refining melting models. By combining evidence from petrology, geochemistry and geophysics the mysteries that attend the generation of melt in the mantle wedge can be resolved.

A reconfigurable image tube using an external electronic image readout

NASA Astrophysics Data System (ADS)

Lapington, J. S.; Howorth, J. R.; Milnes, J. S.

2005-08-01

We have designed and built a sealed tube microchannel plate (MCP) intensifier for optical/NUV photon counting applications suitable for 18, 25 and 40 mm diameter formats. The intensifier uses an electronic image readout to provide direct conversion of event position into electronic signals, without the drawbacks associated with phosphor screens and subsequent optical detection. The Image Charge technique is used to remove the readout from the intensifier vacuum enclosure, obviating the requirement for additional electrical vacuum feedthroughs and for the readout pattern to be UHV compatible. The charge signal from an MCP intensifier is capacitively coupled via a thin dielectric vacuum window to the electronic image readout, which is external to the sealed intensifier tube. The readout pattern is a separate item held in proximity to the dielectric window and can be easily detached, making the system easily reconfigurable. Since the readout pattern detects induced charge and is external to the tube, it can be constructed as a multilayer, eliminating the requirement for narrow insulator gaps and allowing it to be constructed using standard PCB manufacturing tolerances. We describe two readout patterns, the tetra wedge anode (TWA), an optimized 4 electrode device similar to the wedge and strip anode (WSA) but with a factor 2 improvement in resolution, and an 8 channel high speed 50 ohm device, both manufactured as multilayer PCBs. We present results of the detector imaging performance, image resolution, linearity and stability, and discuss the development of an integrated readout and electronics device based on these designs.

Numerical simulation of turbulent flow and heat transfer in the wedge-shaped liquid metal pool of a twin-roll caster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seyedein, S.H.; Hasan, H.

1997-03-01

Controlled flow and heat transfer are important for the quality of a strip in a twin-roll continuous casting process. A numerical study was carried out to investigate the two-dimensional turbulent flow and heat transfer in the liquid stainless-steel-filled wedge-shaped cavity formed by the two counterrotating rolls in a twin-roll continuous casting system. The turbulent characteristics of the flow were modeled using a low-Reynolds-number {kappa}-{epsilon} turbulence model due to Launder and Sharma. The arbitrary nature of the computational domain was accounted for through the use of a nonorthogonal boundary-fitted coordinate system on a staggered grid. A control-volume-based finite difference scheme wasmore » used to solve the transformed transport equations. This study is primarily focused on elucidating the inlet superheat dissipation in the melt pool with the rolls being maintained at a constant liquidus temperature of the steel. A parametric study was carried out to ascertain the effect of the inlet superheat, the casting speed, and the roll gap at the nip of the rotating rolls on the flow and heat transfer characteristics. The velocity fields show two counterrotating recirculation zones in the upstream region. The local Nusselt number on the roll surface shows significant variations. The contours of temperature and turbulent viscosity show the complex nature of the turbulent transport phenomena to be expected in a twin-roll casting process.« less

Proximal opening wedge osteotomy with wedge-plate fixation compared with proximal chevron osteotomy for the treatment of hallux valgus: a prospective, randomized study.

PubMed

Glazebrook, Mark; Copithorne, Peter; Boyd, Gordon; Daniels, Timothy; Lalonde, Karl-André; Francis, Patricia; Hickey, Michael

2014-10-01

Hallux valgus with an increased intermetatarsal angle is usually treated with a proximal metatarsal osteotomy. The proximal chevron osteotomy is commonly used but is technically difficult. This study compares the proximal opening wedge osteotomy of the first metatarsal with the proximal chevron osteotomy for the treatment of hallux valgus with an increased intermetatarsal angle. This prospective, randomized multicenter (three-center) study was based on the clinical outcome scores of the Short Form-36, the American Orthopaedic Foot & Ankle Society forefoot questionnaire, and the visual analog scale for pain, activity, and patient satisfaction. Subjects were assessed prior to surgery and at three, six, and twelve months postoperatively. Surgeon preference was evaluated based on questionnaires and the operative times required for each procedure. No significant differences were found for any of the patients' clinical outcome measurements between the two procedures. The proximal opening wedge osteotomy was found to lengthen, and the proximal chevron osteotomy was found to shorten, the first metatarsal. The intermetatarsal angles improved (decreased) significantly, from 14.8° ± 3.2° to 9.1° ± 2.9 (mean and standard deviation) after a proximal opening wedge osteotomy and from 14.6° ± 3.9° to 11.3° ± 4.0° after a proximal chevron osteotomy (p < 0.05 for both). Operative time required for performing a proximal opening wedge osteotomy is similar to that required for performing a proximal chevron osteotomy (mean and standard deviation, 67.1 ± 16.5 minutes compared with 69.9 ± 18.6 minutes; p = 0.510). Opening wedge and proximal chevron osteotomies have comparable radiographic outcomes and comparable clinical outcomes for pain, satisfaction, and function. The proximal opening wedge osteotomy lengthens, and the proximal chevron osteotomy shortens, the first metatarsal. The proximal opening wedge osteotomy was subjectively less technically demanding and was preferred by the orthopaedic surgeons in this study. Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence. Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.

3D modeling of seismic waves propagation in the Israeli continental shelf: soft sediments, buried canyons and their effects.

NASA Astrophysics Data System (ADS)

Tsesarsky, M.; Volk, O.; Shani-Kadmiel, S.; Gvirtzman, Z.

2016-12-01

Sedimentary wedges underlay many coastal areas, specifically along passive continental margins. Although a large portion of the world`s population is concentrated along coastal areas, relatively few studies investigated the seismic hazard related to internal structure of these wedges. This is particularly important, when the passive margin is located in proximity to active plate boundaries. Sedimentry wedges have low angles compared to fault bounded basins, hence commonly treated using 1D methods. In various locations the sedimentary wedges are transected by deep buried canyons typically filled with sediments softer than their surrounding bedrock. Such structures are found is the Mediterranean coast of Israel. Here, a sedimentary wedge and buried canyons underlay some of the country's most densely populated regions. Seismic sources can be found both at sea and on land at epicentral distances ranging from 50 to 200 km. Although this region has a proven seismic record, it has, like many other parts of the world, limited instrumental coverage and long return periods. This makes assessment of ground motions in a future earthquake difficult and highlights the importance of non-instrumental methods. We employ numerical modeling (SW4 FD code) to study seismic ground motions and their amplification atop the sedimentary wedge and canyons. This goal is a part of a larger objective aiming at developing a systematic approach for distinction between individual contributions of basin structures to the highly complex overall basin response. We show that the sedimentary wedge and buried canyon both exhibit a unique response and modeling them as one-dimensional structures could significantly underestimate seismic hazard. The sedimentary wedge exhibit amplification ratios, relative to a horizontally layered model, up to a factor of 2. This is mainly due to the amplification of Rayleigh waves traveling into the wedge from its thin side. The buried canyon structure shows a simple, "easy to use" response with considerably high PGV values and amplification ratios of up to 3 along its axis. This response is due to a geometrical focusing effect caused by the convex shape of the canyon's floor. The canyon's response is significant even where the canyon is buried deep under the surface.

Planar shock reflection on a wedged concave reflector

NASA Astrophysics Data System (ADS)

Yu, Fan-Ming; Sheu, Kuen-Dong

2001-04-01

The investigation of shock reflection and shock diffraction phenomena upon a wedged concave reflector produced by a planar incident shock wave has been done in the shock tube facility of Institute of Aeronautics and Astronautics, National Cheng- Kung University. The experiment proceeds upon three wedged concave reflectors models the upper and lower wedge angles arrangement of them are (50 degrees, 50 degrees) - 35 degrees, 35 degrees) and (50 degrees, 35 degrees), respectively. They were tested at Mach numbers of 1.2 - 1.65 and 2.0. On the first reflector, following the regular reflection on the 50 degree-wedged surface by the incident shock wave, a Mach shock diffraction behavior has been observed as shock moves outward from the apex of the reflector. On the apex of the reflector, it behaviors as a sector of the blast shock moving on a diverging channel. On the shadowgraph pictures it has been observed there exists a pattern of gas dynamics focus upon the second reflector. The Mach reflection from the 35 degree- wedged surface as being generated by the planar incident shock wave, on which the overlapping of the two triple points from both wedged surface offers the focusing mechanism. The shock interference, which proceeds by the Mach shock reflection and the regular shock diffraction from the reflector, generates a very complicate rolling-up of slip lines system. On the third reflector, the mixed shock interference behavior has been observed of which two diffraction shocks from concave 50 degree-wedged surface and 35 degree-wedged surface interfere with each other. The measurement of the peak pressure along a ray from the model apex parallel to incident shock direction indicates that the measured maximum pressure rising is larger near the apex of the reflector. Considering the measured maximum pressure increment due to the reflection shocks indicate that the wave strength upon large apex angle reflector is greater than it is upon small apex angle reflector. However, as considering the measured maximum pressure increment following the diffraction shocks, the results show that due to the focusing process upon (35 degree, 35 degree) reflector, it is of the largest increment.

Spacing of Imbricated Thrust Faults and the Strength of Thrust-Belts and Accretionary Wedges

NASA Astrophysics Data System (ADS)

Ito, G.; Regensburger, P. V.; Moore, G. F.

2017-12-01

The pattern of imbricated thrust blocks is a prominent characteristic of the large-scale structure of thrust-belts and accretionary wedges around the world. Mechanical models of these systems have a rich history from laboratory analogs, and more recently from computational simulations, most of which, qualitatively reproduce the regular patterns of imbricated thrusts seen in nature. Despite the prevalence of these patterns in nature and in models, our knowledge of what controls the spacing of the thrusts remains immature at best. We tackle this problem using a finite difference, particle-in-cell method that simulates visco-elastic-plastic deformation with a Mohr-Coulomb brittle failure criterion. The model simulates a horizontal base that moves toward a rigid vertical backstop, carrying with it an overlying layer of crust. The crustal layer has a greater frictional strength than the base, is cohesive, and is initially uniform in thickness. As the layer contracts, a series of thrust blocks immerge sequentially and form a wedge having a mean taper consistent with that predicted by a noncohesive, critical Coulomb wedge. The widths of the thrust blocks (or spacing between adjacent thrusts) are greatest at the front of the wedge, tend to decrease with continued contraction, and then tend toward a pseudo-steady, minimum width. Numerous experiments show that the characteristic spacing of thrusts increases with the brittle strength of the wedge material (cohesion + friction) and decreases with increasing basal friction for low (<8°) taper angles. These relations are consistent with predictions of the elastic stresses forward of the frontal thrust and at what distance the differential stress exceeds the brittle threshold to form a new frontal thrust. Hence the characteristic spacing of the thrusts across the whole wedge is largely inherited at the very front of the wedge. Our aim is to develop scaling laws that will illuminate the basic physical processes controlling systems, as well as allow researchers to use observations of thrust spacing as an independent constraint on the brittle strength of wedges as well as their bases.

Contemporary sand wedge development in seasonally frozen ground and paleoenvironmental implications

NASA Astrophysics Data System (ADS)

Wolfe, Stephen A.; Morse, Peter D.; Neudorf, Christina M.; Kokelj, Steven V.; Lian, Olav B.; O'Neill, H. Brendan

2018-05-01

Contemporary sand wedges and sand veins are active in seasonally frozen ground within the extensive discontinuous permafrost zone in Northwest Territories, Canada. The region has a subarctic continental climate with 291 mm a-1 precipitation, -4.1 °C mean annual air temperature, warm summers (July mean 17.0 °C), and cold winters (January mean -26.6 °C). Five years of continuous observations indicate that interannual variation of the ground thermal regime is dominantly controlled by winter air temperature and snow cover conditions. At sandy sites, thin snow cover and high thermal conductivity promote rapid freezing, high rates of ground cooling, and low near-surface ground temperatures (-15 to -25 °C), resulting in thermal contraction cracking to depths of 1.2 m. Cracking potentials are high in sandy soils when air temperatures are <-30 °C on successive days, mean freezing season air temperatures are ≤-17 °C, and snow cover is <0.15 m thick. In contrast, surface conditions in peatlands maintain permafrost, but thermal contraction cracking does not occur because thicker snow cover and the thermal properties of peat prolong freezeback and maintain higher winter ground temperatures. A combination of radiocarbon dating, optical dating, and stratigraphic observations were used to differentiate sand wedge types and formation histories. Thermal contraction cracks that develop in the sandy terrain are filled by surface (allochthonous) and/or host (autochthonous) material during the thaw season. Epigenetic sand wedges infilled with allochthonous sand develop within former beach sediments beneath an active eolian sand sheet. Narrower and deeper syngenetic wedges developed within aggrading eolian sand sheets, whereas wider and shallower antisyngenetic wedges developed in areas of active erosion. Thermal contraction cracking beneath vegetation-stabilized surfaces leads to crack infilling by autochthonous host and overlying organic material, with resultant downturning and subsidence of adjacent strata. Sand wedge development in seasonally frozen ground with limited surface sediment supply can result in stratigraphy similar to ice-wedge and composite-wedge pseudomorphs. Therefore, caution must be exercised when interpreting this suite of forms and inferring paleoenvironments.

Controlling direct contact force for wet adhesion with different wedged film stabilities

NASA Astrophysics Data System (ADS)

Li, Meng; Xie, Jun; Shi, Liping; Huang, Wei; Wang, Xiaolei

2018-04-01

In solid–liquid–solid adhesive systems, wedged films often feature instability at microscopic thicknesses, which can easily disrupt the adhesive strength of their remarkable direct contact force. Here, sodium dodecyl sulfate (SDS) was employed to tune the instability of adhesion in wedged glass–water–rubber films, achieving controllable direct contact. Experimental results showed that the supplement of SDS molecules significantly weakened the direct contact force for wet adhesion and eliminated it at high concentrations. The underlying reason was suggested to be the repulsive double-layer force caused by SDS molecules, which lowers the instability of the wedged film and balances the preload, disrupting the direct contact in wet adhesion.

Analytical solutions for two-dimensional Stokes flow singularities in a no-slip wedge of arbitrary angle

PubMed Central

Brzezicki, Samuel J.

2017-01-01

An analytical method to find the flow generated by the basic singularities of Stokes flow in a wedge of arbitrary angle is presented. Specifically, we solve a biharmonic equation for the stream function of the flow generated by a point stresslet singularity and satisfying no-slip boundary conditions on the two walls of the wedge. The method, which is readily adapted to any other singularity type, takes full account of any transcendental singularities arising at the corner of the wedge. The approach is also applicable to problems of plane strain/stress of an elastic solid where the biharmonic equation also governs the Airy stress function. PMID:28690412

Analytical solutions for two-dimensional Stokes flow singularities in a no-slip wedge of arbitrary angle.

PubMed

Crowdy, Darren G; Brzezicki, Samuel J

2017-06-01

An analytical method to find the flow generated by the basic singularities of Stokes flow in a wedge of arbitrary angle is presented. Specifically, we solve a biharmonic equation for the stream function of the flow generated by a point stresslet singularity and satisfying no-slip boundary conditions on the two walls of the wedge. The method, which is readily adapted to any other singularity type, takes full account of any transcendental singularities arising at the corner of the wedge. The approach is also applicable to problems of plane strain/stress of an elastic solid where the biharmonic equation also governs the Airy stress function.

Physical optics-based diffraction coefficient for a wedge with different face impedances.

PubMed

Umul, Yusuf Ziya

2018-03-20

A new diffraction field expression is introduced with the aid of the modified theory of physical optics for a wedge with different face impedances. First, the scattered geometrical optics fields are determined when both faces of the wedge are illuminated by the incident wave. The geometrical optics waves are then expressed in terms of the sum of two different fields that occur for different impedance wedges. The diffracted fields are determined for the two cases separately, and the total diffracted field is obtained as a sum of these waves. Lastly, the uniform field expressions are obtained, and the resultant fields are numerically compared with the solution of Maliuzhinets.

Telescope with a wide field of view internal optical scanner

NASA Technical Reports Server (NTRS)

Zheng, Yunhui (Inventor); Degnan, III, John James (Inventor)

2012-01-01

A telescope with internal scanner utilizing either a single optical wedge scanner or a dual optical wedge scanner and a controller arranged to control a synchronous rotation of the first and/or second optical wedges, the wedges constructed and arranged to scan light redirected by topological surfaces and/or volumetric scatterers. The telescope with internal scanner further incorporates a first converging optical element that receives the redirected light and transmits the redirected light to the scanner, and a second converging optical element within the light path between the first optical element and the scanner arranged to reduce an area of impact on the scanner of the beam collected by the first optical element.

Regional Anesthesia to Scalp for Craniotomy: Innovation With Innervation.

PubMed

Jayaram, Kavitha; Srilata, Moningi; Kulkarni, Dilipkumar; Ramachandran, Gopinath

2016-01-01

Effective management and pain prevention is of great importance to avoid postoperative complications such as hypertension, agitation, and vomiting. All these adverse events may lead to elevation in intracranial pressure and, in turn, unfavorable outcome and prolonged hospital stay. Development of multiple methods of analgesia may contribute to the alleviation of problems due to pain. We tested the effectiveness of bilateral maxillary block with greater and lesser occipital nerve block for providing analgesia to the scalp. This study was undertaken in 40 patients scheduled for craniotomy. Before skin incision, patients were assigned randomly to receive either bilateral maxillary (group M) or scalp block (group S). Data on intraoperative hemodynamics, postoperative analgesia, and sedation were collected and analyzed for statistical significance. The primary outcome was the visual analog pain score. It was similar between the 2 groups at 1, 2, and 4 hours after extubation. At 12 hours, the maxillary block group had better analgesia (mean visual analog score: 3.4 cm for group M and 4.1 cm for group S with P-value of 0.0002) and sedation scores. Intraoperatively, there was no difference in the heart rate, blood pressure, and the anesthetic requirements between both the groups. Three patients in group S required fentanyl supplementation in the intraoperative period. There were no adverse events noted in the perioperative period among both the groups. Maxillary block along with greater and lesser occipital nerve block is an effective alternative to scalp block for craniotomy and has longer duration of analgesia.

Pathologic Progression, Possible Origin, and Management of Multiple Primary Intracranial Neuroendocrine Carcinomas.

PubMed

Cao, Jingwei; Xu, Wenzhe; Du, Zhenhui; Sun, Bin; Li, Feng; Liu, Yuguang

2017-10-01

Primary intracranial neuroendocrine carcinomas (NECs) are extremely rare malignant tumors with no previous reports of multiple ones in the literatures. The clinical presentation, preoperative and reexamined magnetic resonance imaging findings, as well as histopathologic studies of a 56-year-old female subject with multiple intracranial NECs mimicking multiple intracranial meningiomas, who underwent 3 operations with left parietal craniotomy, right occipital parietal craniotomy, and left frontal craniotomy, separately and chronologically, are presented in this article. Noteworthy, the first and second tumors were confirmed as NECs exhibiting histologic characteristics of typical anaplastic meningiomas with features of whorl formation, while the third tumor was a typical NEC with features of organoid cancer nests. In other words, the first 2 lesions were diagnosed as meningioma as opposed to NEC. It was only after the third surgery that the pathology for the first 2 cases was reviewed and had a revised diagnosis. After the third surgical resection, the patient further received whole brain radiotherapy and systemic chemotherapy (temozolomide combined with YH-16). At her 10-month follow-up, the patient achieved a good outcome. Multiple primary intracranial NECs are extremely rare. The tumor might be of arachnoidal or leptomeningeal origin, with histologic patterns that might lead to transformation and/or progression. Maximal surgical resection is warranted for symptomatic mass effect. Postoperative adjuvant treatments including radiotherapy and chemotherapy should be a recommended therapeutic modality. Copyright © 2017 Elsevier Inc. All rights reserved.

Vaccum drainage system application in the management of operation-related non-regional epidural hematoma

PubMed Central

2013-01-01

Background Epidural intracranial hematoma is one of the most common complications of surgeries for intracranial tumors. The non-regional epidural hematoma is related to severe fluctuation of the intracranial pressure during the operation. The traditional management of hematoma evacuation through craniotomy is time-consuming and may aggravate intracranial pressure imbalance, which causes further complications. We designed a method using vaccum epidural drainage system, and tried to evaluate advantage and the disadvantage of this new technique. Methods Seven patients of intracranial tumors were selected. All of the patients received tumor resection and intra-operative non-regional epidural hematoma was confirmed through intra-operative ultrasound or CT scan. The vaccum drainage system was applied. Another ten patients who received craniotomy for intra-operative non-regional epidural hematoma evacuation were selected as comparison. Regular tests, like serial CT scan, were performed afterward to evaluate the effectiveness and to help deciding when to remove the drainage system. Results The vaccum drainage method was effective in epidual hemotoma clearance and prevented recurrent epidural hemorrhage. The drainage systems were removed within 4 days. All of the patients recovered well. No complications related to the drainage system were observed. Conclusions Compared to the traditional craniotomy, the new method of epidural hemoatoma management using vaccum epidural drainage system proved to be as effective in hematoma clearance, and was less-invasive and easier to perform, with less complication, shorter hospitalization, less economic burden, and better prognosis. PMID:23842198

The incidence and risk factors of meningitis after major craniotomy in China: a retrospective cohort study.

PubMed

Chen, Chen; Zhang, Bingyan; Yu, Shenglei; Sun, Feng; Ruan, Qiaoling; Zhang, Wenhong; Shao, Lingyun; Chen, Shu

2014-01-01

Meningitis after neurosurgery can result in severe morbidity and high mortality. Incidence varies among regions and limited data are focused on meningitis after major craniotomy. This retrospective cohort study aimed to determine the incidence, risk factors and microbiological spectrum of postcraniotomy meningitis in a large clinical center of Neurosurgery in China. Patients who underwent neurosurgeries at the Department of Neurosurgery in Huashan Hospital, the largest neurosurgery center in Asia and the Pacific, between 1st January and 31st December, 2008 were selected. Individuals with only shunts, burr holes, stereotactic surgery, transsphenoidal or spinal surgery were excluded. The complete medical records of each case were reviewed, and data on risk factors were extracted and evaluated for meningitis. A total of 65 meningitides were identified among 755 cases in the study, with an incidence of 8.60%. The risk of meningitis was increased by the presence of diabetes mellitus (odds ratio [OR], 6.27; P = 0.009), the use of external ventricular drainage (OR, 4.30; P = 0.003) and the use of lumbar drainage (OR, 17.23; P<0.001). The isolated microorganisms included Acinetobacter baumannii, Enterococcus sp, Streptococcus intermedius and Klebsiella pneumonia. Meningitis remains an important source of morbidity and mortality after major craniotomy. Diabetic patients or those with cerebral spinal fluid shunts carry significant high risk of infection. Thus, identification of the risk factors as soon as possible will help physicians to improve patient care.

The Incidence and Risk Factors of Meningitis after Major Craniotomy in China: A Retrospective Cohort Study

PubMed Central

Yu, Shenglei; Sun, Feng; Ruan, Qiaoling; Zhang, Wenhong; Shao, Lingyun; Chen, Shu

2014-01-01

Background Meningitis after neurosurgery can result in severe morbidity and high mortality. Incidence varies among regions and limited data are focused on meningitis after major craniotomy. Aim This retrospective cohort study aimed to determine the incidence, risk factors and microbiological spectrum of postcraniotomy meningitis in a large clinical center of Neurosurgery in China. Methods Patients who underwent neurosurgeries at the Department of Neurosurgery in Huashan Hospital, the largest neurosurgery center in Asia and the Pacific, between 1stJanuary and 31st December, 2008 were selected. Individuals with only shunts, burr holes, stereotactic surgery, transsphenoidal or spinal surgery were excluded. The complete medical records of each case were reviewed, and data on risk factors were extracted and evaluated for meningitis. Results A total of 65 meningitides were identified among 755 cases in the study, with an incidence of 8.60%. The risk of meningitis was increased by the presence of diabetes mellitus (odds ratio [OR], 6.27; P = 0.009), the use of external ventricular drainage (OR, 4.30; P = 0.003) and the use of lumbar drainage (OR, 17.23; P<0.001). The isolated microorganisms included Acinetobacter baumannii, Enterococcus sp, Streptococcus intermedius and Klebsiella pneumonia. Conclusions Meningitis remains an important source of morbidity and mortality after major craniotomy. Diabetic patients or those with cerebral spinal fluid shunts carry significant high risk of infection. Thus, identification of the risk factors as soon as possible will help physicians to improve patient care. PMID:25003204

Remote cerebellar hemorrhage following supratentorial craniotomy.

PubMed

Huang, Chih-Yuan; Lee, Po-Hsuan; Lin, Sheng-Hsiang; Chuang, Ming-Tsung; Sun, Yuan-Ting; Hung, Yu-Chang; Lee, E-Jian

2012-06-01

Cerebellar hemorrhage remote from the site of surgery may complicate neurosurgical procedure. The exact pathophysiology of this type of hemorrhage is poorly understood. We retrospectively compared 16 patients who had remote cerebellar hemorrhage (RCH) with a case-matched control cohort, to determine the significance of perisurgical and surgical factors that may predispose patients to such bleeding events. From 1 June 2005 to 31 December 2008, postoperative routine head computed tomographic (CT) scan was performed in our institution and 16 patients with RCH after supratentorial neurosurgical procedure were identified. The medical charts of these 16 cases and a control cohort of 64 patients were recorded. All parameters were analyzed with regards to various variables. The incidence RCH after supratentorial craniotomy increased after postoperative computed tomographic scan. The mechanism of cerebellar hemorrhage in this series of patients is most likely multifactorial. Several variables showed a significant association with the occurrence of RCH. Multivariate analysis indicated that the following two factors independently correlated with occurrence of RCH: (1) postoperative epidural drainage amount; and (2) history of previous cerebrovascular accident (CVA) with cerebral atrophy. All cases with RCH underwent medical treatment and no neurological sequelae associated with RCH. Postoperative epidural drainage amount and history of previous CVA with cerebral atrophy can reliably predict the occurrence of cerebellar hemorrhage after supratentorial craniotomy. One of the most important strategies to minimize hazardous complications is to be aware of these potential risk factors and to take action to prevent them.

Awake craniotomy for brain lesions within and near the primary motor area: A retrospective analysis of factors associated with worsened paresis in 102 consecutive patients

PubMed Central

Shinoura, Nobusada; Midorikawa, Akira; Yamada, Ryoji; Hana, Taijun; Saito, Akira; Hiromitsu, Kentaro; Itoi, Chisato; Saito, Syoko; Yagi, Kazuo

2013-01-01

Background: We analyzed factors associated with worsened paresis in a large series of patients with brain lesions located within or near the primary motor area (M1) to establish protocols for safe, awake craniotomy of eloquent lesions. Methods: We studied patients with brain lesions involving M1, the premotor area (PMA) and the primary sensory area (S1), who underwent awake craniotomy (n = 102). In addition to evaluating paresis before, during, and one month after surgery, the following parameters were analyzed: Intraoperative complications; success or failure of awake surgery; tumor type (A or B), tumor location, tumor histology, tumor size, and completeness of resection. Results: Worsened paresis at one month of follow-up was significantly associated with failure of awake surgery, intraoperative complications and worsened paresis immediately after surgery, which in turn was significantly associated with intraoperative worsening of paresis. Intraoperative worsening of paresis was significantly related to preoperative paresis, type A tumor (motor tract running in close proximity to and compressed by the tumor), tumor location within or including M1 and partial removal (PR) of the tumor. Conclusions: Successful awake surgery and prevention of deterioration of paresis immediately after surgery without intraoperative complications may help prevent worsening of paresis at one month. Factors associated with intraoperative worsening of paresis were preoperative motor deficit, type A and tumor location in M1, possibly leading to PR of the tumor. PMID:24381792

Occipital Artery to Middle Cerebral Artery Bypass in Cases of Unavailable Superficial Temporal Artery.

PubMed

Hirano, Tsukasa; Mikami, Takeshi; Suzuki, Hime; Hirano, Toru; Kimura, Yusuke; Komatsu, Katusya; Akiyama, Yukinori; Wanibuchi, Masahiko; Mikuni, Nobuhiro

2018-04-01

In neurosurgery, extracranial-to-intracranial (EC-IC) bypass surgery is necessary for patients who have undergone surgery in which the superficial temporal artery (STA) was already used for a different bypass procedure or was damaged. Here we report our experience with EC-IC bypass using the occipital artery (OA) in patients in whom the STA was unavailable, and discuss the technical considerations and pitfalls. Five patients with ischemic-onset moyamoya disease and atherosclerotic disease were included. Two patterns of skin incisions were planned according to the OA pathway and recipient artery location. In one of these methods, a skin incision is made above the OA, and a craniotomy is performed under this incision after OA dissection. In the other method, a skin incision is made above the OA to enable its dissection, and a craniotomy is performed via a separate skin incision. No major perioperative complications developed in any of the 5 cases, and bypass patency was confirmed in all patients. There was a significant difference between the preoperative and postoperative asymmetry ratios of the mean transit time values. Our findings suggest that OA-to-middle cerebral artery (MCA) bypass is a simple and effective technique in patients in whom the STA was already used or was damaged by previous intracranial revascularization or craniotomy. This procedure could be an alternative to STA-MCA bypass in patients without an available STA. Copyright © 2018 Elsevier Inc. All rights reserved.

Novel techniques of real-time blood flow and functional mapping: technical note.

PubMed

Kamada, Kyousuke; Ogawa, Hiroshi; Saito, Masato; Tamura, Yukie; Anei, Ryogo; Kapeller, Christoph; Hayashi, Hideaki; Prueckl, Robert; Guger, Christoph

2014-01-01

There are two main approaches to intraoperative monitoring in neurosurgery. One approach is related to fluorescent phenomena and the other is related to oscillatory neuronal activity. We developed novel techniques to visualize blood flow (BF) conditions in real time, based on indocyanine green videography (ICG-VG) and the electrophysiological phenomenon of high gamma activity (HGA). We investigated the use of ICG-VG in four patients with moyamoya disease and two with arteriovenous malformation (AVM), and we investigated the use of real-time HGA mapping in four patients with brain tumors who underwent lesion resection with awake craniotomy. Real-time data processing of ICG-VG was based on perfusion imaging, which generated parameters including arrival time (AT), mean transit time (MTT), and BF of brain surface vessels. During awake craniotomy, we analyzed the frequency components of brain oscillation and performed real-time HGA mapping to identify functional areas. Processed results were projected on a wireless monitor linked to the operating microscope. After revascularization for moyamoya disease, AT and BF were significantly shortened and increased, respectively, suggesting hyperperfusion. Real-time fusion images on the wireless monitor provided anatomical, BF, and functional information simultaneously, and allowed the resection of AVMs under the microscope. Real-time HGA mapping during awake craniotomy rapidly indicated the eloquent areas of motor and language function and significantly shortened the operation time. These novel techniques, which we introduced might improve the reliability of intraoperative monitoring and enable the development of rational and objective surgical strategies.

Novel Techniques of Real-time Blood Flow and Functional Mapping: Technical Note

PubMed Central

KAMADA, Kyousuke; OGAWA, Hiroshi; SAITO, Masato; TAMURA, Yukie; ANEI, Ryogo; KAPELLER, Christoph; HAYASHI, Hideaki; PRUECKL, Robert; GUGER, Christoph

2014-01-01

There are two main approaches to intraoperative monitoring in neurosurgery. One approach is related to fluorescent phenomena and the other is related to oscillatory neuronal activity. We developed novel techniques to visualize blood flow (BF) conditions in real time, based on indocyanine green videography (ICG-VG) and the electrophysiological phenomenon of high gamma activity (HGA). We investigated the use of ICG-VG in four patients with moyamoya disease and two with arteriovenous malformation (AVM), and we investigated the use of real-time HGA mapping in four patients with brain tumors who underwent lesion resection with awake craniotomy. Real-time data processing of ICG-VG was based on perfusion imaging, which generated parameters including arrival time (AT), mean transit time (MTT), and BF of brain surface vessels. During awake craniotomy, we analyzed the frequency components of brain oscillation and performed real-time HGA mapping to identify functional areas. Processed results were projected on a wireless monitor linked to the operating microscope. After revascularization for moyamoya disease, AT and BF were significantly shortened and increased, respectively, suggesting hyperperfusion. Real-time fusion images on the wireless monitor provided anatomical, BF, and functional information simultaneously, and allowed the resection of AVMs under the microscope. Real-time HGA mapping during awake craniotomy rapidly indicated the eloquent areas of motor and language function and significantly shortened the operation time. These novel techniques, which we introduced might improve the reliability of intraoperative monitoring and enable the development of rational and objective surgical strategies. PMID:25263624

Determination of surgical variables for a brain shift correction pipeline using an Android application

NASA Astrophysics Data System (ADS)

Vijayan, Rohan; Conley, Rebekah H.; Thompson, Reid C.; Clements, Logan W.; Miga, Michael I.

2016-03-01

Brain shift describes the deformation that the brain undergoes from mechanical and physiological effects typically during a neurosurgical or neurointerventional procedure. With respect to image guidance techniques, brain shift has been shown to compromise the fidelity of these approaches. In recent work, a computational pipeline has been developed to predict "brain shift" based on preoperatively determined surgical variables (such as head orientation), and subsequently correct preoperative images to more closely match the intraoperative state of the brain. However, a clinical workflow difficulty in the execution of this pipeline has been acquiring the surgical variables by the neurosurgeon prior to surgery. In order to simplify and expedite this process, an Android, Java-based application designed for tablets was developed to provide the neurosurgeon with the ability to orient 3D computer graphic models of the patient's head, determine expected location and size of the craniotomy, and provide the trajectory into the tumor. These variables are exported for use as inputs for the biomechanical models of the preoperative computing phase for the brain shift correction pipeline. The accuracy of the application's exported data was determined by comparing it to data acquired from the physical execution of the surgeon's plan on a phantom head. Results indicated good overlap of craniotomy predictions, craniotomy centroid locations, and estimates of patient's head orientation with respect to gravity. However, improvements in the app interface and mock surgical setup are needed to minimize error.

Measuring Liquid-Level Utilizing Wedge Wave

PubMed Central

Honma, Yudai; Mori, Masayuki; Ihara, Ikuo

2017-01-01

A new technique for measuring liquid-level utilizing wedge wave is presented and demonstrated through FEM simulation and a corresponding experiment. The velocities of wedge waves in the air and the water, and the sensitivities for the measurement, are compared with the simulation and the results obtained in the experiments. Combining the simulation and the measurement theory, it is verified that the foundation framework for the methods is available. The liquid-level sensing is carried out using the aluminum waveguide with a 30° wedge in the water. The liquid-level is proportional to the traveling time of the mode 1 wedge wave. The standard deviations and the uncertainties of the measurement are 0.65 mm and 0.21 mm using interface echo, and 0.39 mm and 0.12 mm utilized by end echo, which are smaller than the industry standard of 1.5 mm. The measurement resolutions are 7.68 μm using the interface echo, which is the smallest among all the guided acoustic wave-based liquid-level sensing. PMID:29267232

16 CFR Figure 1 to Part 1213 - Wedge Block for Tests in § 1213.4(a), (b), and (c)

Code of Federal Regulations, 2010 CFR

2010-01-01

... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Wedge Block for Tests in § 1213.4(a), (b), and (c) 1 Figure 1 to Part 1213 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER... 1 to Part 1213—Wedge Block for Tests in § 1213.4(a), (b), and (c) ER22DE99.007 ...

Chevron closing base wedge bunionectomy.

PubMed

Bruyn, J M

1993-01-01

The Chevron-base wedge Association for Osteosynthesis fixated bunionectomy provides a stable, aggressive correction of the severe hallux abducto valgus deformity. It is intended for the bunion requiring a double osteotomy in order to adequately reduce both intermetatarsal and proximal articular facet angle with minimal shortening and elevation. This article presents the rationale for the procedure, technique, and a 4-year follow-up of six patients with eight Chevron-base wedge bunionectomies.

Determination of refractive index of a simple negative, positive, or zero power lens using wedged plated interferometer

NASA Technical Reports Server (NTRS)

Shukla, R. P.; Perera, G. M.; George, M. C.; Venkateswarlu, P.

1990-01-01

A nondestructive technique for measuring the refractive index of a negative lens using a wedged plate interferometer is described. The method can be also used for measuring the refractive index of convex or zero power lenses. Schematic diagrams are presented for the use of a wedged plate interferometer for measuring the refractive index of a concave lens and of a convex lens.

27. VIEW NORTHWEST FROM DECKING ON SOUTHEAST CORNER OF PIVOT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

27. VIEW NORTHWEST FROM DECKING ON SOUTHEAST CORNER OF PIVOT PIER, DRIVE SYSTEM FOR SWING-SPAN INCLUDES: (from left to right) WEDGE DRIVE GEAR BOX, SHAFTS TO WEDGE DRIVE DRIVE, WEDGE DRIVE CRANK SHAFTS, ELECTRIC MOTOR, INTERNATIONAL HARVESTER GASOLINE ENGINE, CONTROL RODS FOR STARTING AND CHOKING ENGINE, PIVOT (bottom center), AND TRACK ON CONCRETE PIER - Tipers Bridge, Spanning Great Wicomico River at State Route 200, Kilmarnock, Lancaster County, VA

Optical Angular Motion Sensor

DTIC Science & Technology

1975-04-01

wedge at 10 Hz Background Radiation Completed Input Power Partially Transients, ripple and reverse Completed polarity power tests not per- formed...cases, indicating that the ACC was functioning properly. The changes seen were attributed to wedge angles and birefringent effects in the attenuators...noise for testing and is not within the specified value. 9.5.2 Method 2 A counter-rotating wedge of 15 arc minutes total deflection was used to measure

Electrolytic cell. [For separating anolyte and catholyte

DOEpatents

Bullock, J.S.; Hale, B.D.

1984-09-14

An apparatus is described for the separation of the anolyte and the catholyte during electrolysis. The electrolyte flows through an electrolytic cell between the oppositely charged electrodes. The cell is equipped with a wedge-shaped device, the tapered end being located between the electrodes on the effluent side of the cell. The wedge diverts the flow of the electrolyte to either side of the wedge, substantially separating the anolyte and the catholyte.

Crossing the boundary: experimental investigation of water entry conditions of V-shaped wedges

NASA Astrophysics Data System (ADS)

Xiao, Tingben; Yohann, Daniel; Vincent, Lionel; Jung, Sunghwan; Kanso, Eva

2016-11-01

Seabirds that plunge-dive at high speeds exhibit remarkable abilities to withstand and mitigate impact forces. To minimize these forces, diving birds streamline their shape at impact, entering water with their sharp beak first. Here, we investigate the impact forces on rigid V-shaped wedges crossing the air-water interface at high Weber numbers. We vary the impact velocity V by adjusting the height from which the wedge is dropped. Both a high-speed camera and a force transducer are used to characterize the impact. We found that the splash base and air cavity show little dependence on the impact velocity when rescaling by inertial time d / V , where d is the breadth of the wedge. The peak impact force occurs at time tp smaller than the submersion time ts such that the ratio tp /ts is almost constant for all wedges and impact velocities V. We also found that the maximum impact force, like drag force, scales as AV2 , where A is the cross-sectional area of the wedge. We then propose analytical models of the impact force and splash dynamics. The theoretical predictions agree well with our experimental results. We conclude by commenting on the relevance of these results to understanding the mechanics of diving seabirds. We acknowledge support from the National Science Foundation.

Effect of antipronation foot orthosis geometry on compression of heel and arch soft tissues.

PubMed

Sweeney, Declan; Nester, Christopher; Preece, Stephen; Mickle, Karen

2015-01-01

This study aimed to understand how systematic changes in arch height and two designs of heel wedging affect soft tissues under the foot. Soft tissue thickness under the heel and navicular was measured using ultrasound. Heel pad thickness was measured when subjects were standing on a flat surface and standing on an orthosis with 4 and 8 degree extrinsic wedges and 4 mm and 8 mm intrinsic wedges (n = 27). Arch soft tissue thickness was measured when subjects were standing and when standing on an orthosis with -6 mm, standard, and +6 mm increments in arch height (n = 25). Extrinsic and intrinsic heel wedges significantly increased soft tissue thickness under the heel compared with no orthosis. The 4 and 8 degree extrinsic wedges increased tissue thickness by 28% and 27.6%, respectively, while the 4 mm and 8 mm intrinsic wedges increased thickness by 23% and 14.6%, respectively. Orthotic arch height significantly affected arch soft tissue thickness. Compared with the no orthosis condition, the -6 mm, standard, and +6 mm arch heights decreased arch tissue thickness by 9%, 10%, and 11.8%, respectively. This study demonstrates that change in orthotic geometry creates different plantar soft tissue responses that we expect to affect transmission of force to underlying foot bones.

Cementless Tapered Wedge Femoral Stems Decrease Subsidence in Obese Patients Compared to Traditional Fit-and-Fill Stems.

PubMed

Grant, Tanner W; Lovro, Luke R; Licini, David J; Warth, Lucian C; Ziemba-Davis, Mary; Meneghini, Robert M

2017-03-01

Femoral component stability and resistance to subsidence is critical for osseointegration and clinical success in cementless total hip arthroplasty. The purpose of this study was to radiographically evaluate the anatomic fit and subsidence of 2 different proximally tapered, porous-coated modern cementless femoral component designs. A retrospective cohort study of 126 consecutive cementless total hip arthroplasties was performed. Traditional fit-and-fill stems were implanted in the first 61 hips with the remaining 65 receiving morphometric tapered wedge stems. Preoperative bone morphology was radiographically assessed by the canal flare index. Canal fill in the coronal plane, subsidence, and the sagittal alignment of stems was measured digitally on immediate and 1-month postoperative radiographs. Demographics and canal flare indices were similar between groups. The percentage of femoral canal fill was greater in the tapered wedge compared to the fit-and-fill stem (P = .001). There was significantly less subsidence in the tapered wedge design (0.3 mm) compared to the fit-and-fill design (1.1 mm) (P = .001). Subsidence significantly increased as body mass index (BMI) increased in the fit-and-fill stems, a finding not observed in the tapered wedge design (P = .013). An anatomically designed morphometric tapered wedge femoral stem demonstrated greater axial stability and decreased subsidence with increasing BMI than a traditional fit-and-fill stem. The resistance to subsidence, irrespective of BMI, is likely due to the inherent axial stability of a tapered wedge design and may be the optimal stem design for obese patients. Copyright © 2016 Elsevier Inc. All rights reserved.

The Effects of a Heel Wedge on Hip, Pelvis and Trunk Biomechanics During Squatting in Resistance Trained Individuals.

PubMed

Charlton, Jesse M; Hammond, Connor A; Cochrane, Christopher K; Hatfield, Gillian L; Hunt, Michael A

2017-06-01

Barbell back squats are a popular exercise for developing lower extremity strength and power. However, this exercise has potential injury risks, particularly to the lumbar spine, pelvis, and hip joint. Previous literature suggests heel wedges as a means of favorably adjusting trunk and pelvis kinematics with the intention of reducing such injury risks. Yet no direct biomechanical research exists to support these recommendations. Therefore, the purpose of this study was to examine the effects of heel wedges compared with barefoot on minimally loaded barbell back squats. Fourteen trained male participants performed a barbell back squat in bare feet or with their feet raised bilaterally with a 2.5-cm wooden block while 3-dimensional kinematics, kinetics, and electromyograms were collected. The heel wedge condition elicited significantly less forward trunk flexion angles at peak knee flexion, and peak external hip joint moments (p ≤ 0.05) compared with barefoot conditions. However, no significant differences were observed between conditions for trunk and pelvis angle differences at peak knee flexion (p > 0.05). Lastly, no peak or root mean square differences in muscle activity were elicited between conditions (p > 0.05). Our results lend support for the suggestions provided in literature aimed at using heel wedges as a means of reducing excessive forward trunk flexion. However, the maintenance of a neutral spine, another important safety factor, is not affected by the use of heel wedges. Therefore, heel wedges may be a viable modification for reduction of excessive forward trunk flexion but not for reduction in relative trunk-pelvis flexion during barbell back squats.

Effect of open wedge high tibial osteotomy on the lateral tibiofemoral compartment in sheep. Part II: standard and overcorrection do not cause articular cartilage degeneration.

PubMed

Ziegler, Raphaela; Goebel, Lars; Cucchiarini, Magali; Pape, Dietrich; Madry, Henning

2014-07-01

To evaluate whether medial open wedge high tibial osteotomy (HTO) results in structural changes in the articular cartilage in the lateral tibiofemoral compartment of adult sheep. Three experimental groups received biplanar osteotomies of the right proximal tibiae: (a) closing wedge HTO (4.5° of tibial varus), (b) opening wedge HTO (4.5° tibial valgus; standard correction), and (c) opening wedge HTO (9.5° of valgus; overcorrection), each of which was compared to the contralateral knees that only received an arthrotomy. After 6 months, the macroscopic and microscopic characteristics of the articular cartilage of the lateral tibiofemoral compartment were assessed. The articular cartilage in the central region of the lateral tibial plateau in sheep had a higher safranin O staining intensity and was 4.6-fold thicker than in the periphery (covered by the lateral meniscus). No topographical variation in the type-II collagen immunoreactivity was seen. All lateral tibial plateaus showed osteoarthritic changes in regions not covered by the lateral meniscus. No osteoarthritis was seen in the peripheral submeniscal regions of the lateral tibial plateau and the lateral femoral condyle. Opening wedge HTO resulting in both standard and overcorrection was not associated with significant macroscopic and microscopic structural changes between groups in the articular cartilage of the lateral tibial plateau and femoral condyle after 6 months in vivo. Opening wedge HTO resulting in both standard and overcorrection is a safe procedure for the articular cartilage in an intact lateral tibiofemoral compartment of adult sheep at 6 months postoperatively.

Climate adaptation wedges: a case study of premium wine in the western United States

NASA Astrophysics Data System (ADS)

Diffenbaugh, Noah S.; White, Michael A.; Jones, Gregory V.; Ashfaq, Moetasim

2011-04-01

Design and implementation of effective climate change adaptation activities requires quantitative assessment of the impacts that are likely to occur without adaptation, as well as the fraction of impact that can be avoided through each activity. Here we present a quantitative framework inspired by the greenhouse gas stabilization wedges of Pacala and Socolow. In our proposed framework, the damage avoided by each adaptation activity creates an 'adaptation wedge' relative to the loss that would occur without that adaptation activity. We use premium winegrape suitability in the western United States as an illustrative case study, focusing on the near-term period that covers the years 2000-39. We find that the projected warming over this period results in the loss of suitable winegrape area throughout much of California, including most counties in the high-value North Coast and Central Coast regions. However, in quantifying adaptation wedges for individual high-value counties, we find that a large adaptation wedge can be captured by increasing the severe heat tolerance, including elimination of the 50% loss projected by the end of the 2030-9 period in the North Coast region, and reduction of the projected loss in the Central Coast region from 30% to less than 15%. Increased severe heat tolerance can capture an even larger adaptation wedge in the Pacific Northwest, including conversion of a projected loss of more than 30% in the Columbia Valley region of Washington to a projected gain of more than 150%. We also find that warming projected over the near-term decades has the potential to alter the quality of winegrapes produced in the western US, and we discuss potential actions that could create adaptation wedges given these potential changes in quality. While the present effort represents an initial exploration of one aspect of one industry, the climate adaptation wedge framework could be used to quantitatively evaluate the opportunities and limits of climate adaptation within and across a broad range of natural and human systems.

Minimum number of clusters and comparison of analysis methods for cross sectional stepped wedge cluster randomised trials with binary outcomes: A simulation study.

PubMed

Barker, Daniel; D'Este, Catherine; Campbell, Michael J; McElduff, Patrick

2017-03-09

Stepped wedge cluster randomised trials frequently involve a relatively small number of clusters. The most common frameworks used to analyse data from these types of trials are generalised estimating equations and generalised linear mixed models. A topic of much research into these methods has been their application to cluster randomised trial data and, in particular, the number of clusters required to make reasonable inferences about the intervention effect. However, for stepped wedge trials, which have been claimed by many researchers to have a statistical power advantage over the parallel cluster randomised trial, the minimum number of clusters required has not been investigated. We conducted a simulation study where we considered the most commonly used methods suggested in the literature to analyse cross-sectional stepped wedge cluster randomised trial data. We compared the per cent bias, the type I error rate and power of these methods in a stepped wedge trial setting with a binary outcome, where there are few clusters available and when the appropriate adjustment for a time trend is made, which by design may be confounding the intervention effect. We found that the generalised linear mixed modelling approach is the most consistent when few clusters are available. We also found that none of the common analysis methods for stepped wedge trials were both unbiased and maintained a 5% type I error rate when there were only three clusters. Of the commonly used analysis approaches, we recommend the generalised linear mixed model for small stepped wedge trials with binary outcomes. We also suggest that in a stepped wedge design with three steps, at least two clusters be randomised at each step, to ensure that the intervention effect estimator maintains the nominal 5% significance level and is also reasonably unbiased.

Lateral Wedge Insoles for Reducing Biomechanical Risk Factors for Medial Knee Osteoarthritis Progression: A Systematic Review and Meta-Analysis.

PubMed

Arnold, John B; Wong, Daniel X; Jones, Richard K; Hill, Catherine L; Thewlis, Dominic

2016-07-01

Lateral wedge insoles are intended to reduce biomechanical risk factors of medial knee osteoarthritis (OA) progression, such as increased knee joint load; however, there has been no definitive consensus on this topic. The aim of this systematic review and meta-analysis was to establish the within-subject effects of lateral wedge insoles on knee joint load in people with medial knee OA during walking. Six databases were searched from inception until February 13, 2015. Included studies reported on the immediate biomechanical effects of lateral wedge insoles during walking in people with medial knee OA. Primary outcomes of interest relating to the biomechanical risk of disease progression were the first and second peak external knee adduction moment (EKAM) and knee adduction angular impulse (KAAI). Eligible studies were pooled using random-effects meta-analysis. Eighteen studies were included with a total of 534 participants. Lateral wedge insoles resulted in a small but statistically significant reduction in the first peak EKAM (standardized mean difference [SMD] -0.19; 95% confidence interval [95% CI] -0.23, -0.15) and second peak EKAM (SMD -0.25; 95% CI -0.32, -0.19) with a low level of heterogeneity (I(2)  = 5% and 30%, respectively). There was a favorable but small reduction in the KAAI with lateral wedge insoles (SMD -0.14; 95% CI -0.21, -0.07, I(2)  = 31%). Risk of methodologic bias scores (quality index) ranged from 8 to 13 out of 16. Lateral wedge insoles cause small reductions in the EKAM and KAAI during walking in people with medial knee OA. Current evidence demonstrates that lateral wedge insoles appear ineffective at attenuating structural changes in people with medial knee OA as a whole and may be better suited to targeted use in biomechanical phenotypes associated with larger reductions in knee load. © 2016, American College of Rheumatology.