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Sample records for ankle dorsiflexor motoneurons

  1. Reduction of common synaptic drive to ankle dorsiflexor motoneurons during walking in patients with spinal cord lesion.

    PubMed

    Hansen, N L; Conway, B A; Halliday, D M; Hansen, S; Pyndt, H S; Biering-Sørensen, F; Nielsen, J B

    2005-08-01

    It is possible to obtain information about the synaptic drive to motoneurons during walking by analyzing motor-unit coupling in the time and frequency domains. The purpose of the present study was to compare motor-unit coupling during walking in healthy subjects and patients with incomplete spinal cord lesion to obtain evidence of differences in the motoneuronal drive that result from the lesion. Such information is of importance for development of new strategies for gait restoration. Twenty patients with incomplete spinal cord lesion (SCL) participated in the study. Control experiments were performed in 11 healthy subjects. In all healthy subjects, short-term synchronization was evident in the discharge of tibialis anterior (TA) motor units during the swing phase of treadmill walking. This was identified from the presence of a narrow central peak in cumulant densities constructed from paired EMG recordings and from the presence of significant coherence between these signals in the 10- to 20-Hz band. Such indicators of short-term synchrony were either absent or very small in the patient group. The relationship between the amount of short-term synchrony and the magnitude of the 10- to 20-Hz coherence in the patients is discussed in relation to gait ability. It is suggested that supraspinal drive to the spinal cord is responsible for short-term synchrony and coherence in the 10- to 20-Hz frequency band during walking in healthy subjects. Absence or reduction of these features may serve as physiological markers of impaired supraspinal control of gait in SCL patients. Such markers could have diagnostic and prognostic value in relation to the recovery of locomotion in patients with central motor lesions. PMID:15800077

  2. Modifications in ankle dorsiflexor activation by applying a torque perturbation during walking in persons post-stroke: a case series

    PubMed Central

    2014-01-01

    Background Results obtained in a previous study (Gait Posture 34:358–363, 2011) have shown that, in non-disabled participants, a specific increase in ankle dorsiflexor (Tibialis anterior [TA]) activation can be induced by walking with a torque perturbation that plantarflexes the ankle during the swing phase. After perturbation removal, the increased TA activation persisted temporarily and was associated with a more dorsiflexed ankle during swing. The objective of the present case-series study was to verify if these results can be reproduced in persons post-stroke. Methods Six participants who sustained a stroke walked on a treadmill before, during and after exposure to a torque perturbation applied at the ankle by a robotized ankle-foot orthosis. Spatiotemporal gait parameters, ankle and knee kinematics, and the electromyographic activity of TA and Soleus were recorded. Mean amplitude of the TA burst located around toe off and peak ankle dorsiflexion angle during swing were compared across the 3 walking periods for each participant. Results At the end of the walking period with the perturbation, TA mean amplitude was significantly increased in 4 of the 6 participants. Among these 4 participants, modifications in TA activation persisted after perturbation removal in 3 of them, and led to a statistically significant increase in peak dorsiflexion during swing. Clinical implications This approach may be helpful to evaluate the residual adaptive capacity in the ankle dorsiflexors after a stroke and guide decision-making for the selection of optimal rehabilitation interventions. Future work will investigate the clinical impact of a multiple-session gait training based on this approach in persons presenting a reduced ankle dorsiflexion during the swing phase of walking. PMID:24912626

  3. Gait training facilitates central drive to ankle dorsiflexors in children with cerebral palsy

    PubMed Central

    Petersen, Tue Hvass; Farmer, Simon Francis; Nielsen, Jens Bo

    2015-01-01

    . These data show that daily intensive gait training increases beta and gamma oscillatory drive to ankle dorsiflexor motor neurons and that it improves toe lift and heel strike in children with cerebral palsy. We propose that intensive gait training may produce plastic changes in the corticospinal tract, which are responsible for improvements in gait function. PMID:25623137

  4. Modulation of recurrent inhibition from knee extensors to ankle motoneurones during human walking

    PubMed Central

    Lamy, Jean-Charles; Iglesias, Caroline; Lackmy, Alexandra; Nielsen, Jens Bo; Katz, Rose; Marchand-Pauvert, Véronique

    2008-01-01

    The neural control for muscle coordination during human locomotion involves spinal and supraspinal networks, but little is known about the exact mechanisms implicated. The present study focused on modulation of heteronymous recurrent inhibition from knee extensors to ankle motoneurones at different times in the gait cycle, when quadriceps (Quad) muscle activity overlaps that in tibialis anterior (TA) and soleus (Sol). The effects of femoral nerve stimulation on ankle motoneurones were investigated during treadmill walking and during tonic co-contraction of Quad and TA/Sol while standing. Recurrent inhibition of TA motoneurones depended on the level of background EMG, and was similar during walking and standing for matched background EMG levels. On the other hand, recurrent inhibition in Sol was reduced in early stance, with respect to standing, and enhanced in late stance. Reduced inhibition in Sol was also observed when Quad was coactivated with TA around the time of heel contact, compared to standing at matched background EMG levels in the two muscles. The modulation of recurrent inhibition of Sol during walking might reflect central and/or peripheral control of the Renshaw cells. These modulations could be implicated in the transition phases, from swing to stance to assist Sol activation during the stance phase, and from stance to swing, for its deactivation. PMID:18936080

  5. Isokinetic profile of dorsiflexors and plantar flexors of the ankle--a comparative study of élite versus untrained subjects.

    PubMed

    So, C H; Siu, T O; Chan, K M; Chin, M K; Li, C T

    1994-03-01

    A comparative study was made of the isokinetic characteristics of the ankle (plantar-flexion and dorsiflexion) in young men. Six cyclists, seven gymnasts, 10 soccer players and 25 non-athletic young men were tested on the Cybex II+ dynamometer. Peak torque, torque acceleration energy (TAE), total work and average power were measured. Cyclists had slightly higher (5%) mean plantar flexion than the others, but this was not significant. The situation was reversed for dorsiflexion. Moreover, the average dorsiflexion per unit of plantar flexion was significantly higher in the gymnasts than it was in the cyclists for both torque and work. This suggests that at a specific level of plantar flexion, the gymnasts had stronger dorsiflexion compared with the cyclists and that in sports involving jumping and running, increased attention should be given to strengthening the antagonist muscle groups (dorsiflexors) in order to achieve greater agonist-to-antagonist muscle balance thus preventing injury. The non-athletic subjects had substantially lower endurance capability in both flexors as measured by the endurance ratio. This implies that identifiable specialization in particular muscles results from training or participating in specialized sports. PMID:8044488

  6. Isokinetic profile of dorsiflexors and plantar flexors of the ankle--a comparative study of élite versus untrained subjects.

    PubMed Central

    So, C H; Siu, T O; Chan, K M; Chin, M K; Li, C T

    1994-01-01

    A comparative study was made of the isokinetic characteristics of the ankle (plantar-flexion and dorsiflexion) in young men. Six cyclists, seven gymnasts, 10 soccer players and 25 non-athletic young men were tested on the Cybex II+ dynamometer. Peak torque, torque acceleration energy (TAE), total work and average power were measured. Cyclists had slightly higher (5%) mean plantar flexion than the others, but this was not significant. The situation was reversed for dorsiflexion. Moreover, the average dorsiflexion per unit of plantar flexion was significantly higher in the gymnasts than it was in the cyclists for both torque and work. This suggests that at a specific level of plantar flexion, the gymnasts had stronger dorsiflexion compared with the cyclists and that in sports involving jumping and running, increased attention should be given to strengthening the antagonist muscle groups (dorsiflexors) in order to achieve greater agonist-to-antagonist muscle balance thus preventing injury. The non-athletic subjects had substantially lower endurance capability in both flexors as measured by the endurance ratio. This implies that identifiable specialization in particular muscles results from training or participating in specialized sports. PMID:8044488

  7. Electrical Stimulation of Low-Threshold Proprioceptive Fibers in the Adult Rat Increases Density of Glutamatergic and Cholinergic Terminals on Ankle Extensor α-Motoneurons.

    PubMed

    Gajewska-Woźniak, Olga; Grycz, Kamil; Czarkowska-Bauch, Julita; Skup, Małgorzata

    2016-01-01

    The effects of stimulation of low-threshold proprioceptive afferents in the tibial nerve on two types of excitatory inputs to α-motoneurons were tested. The first input is formed by glutamatergic Ia sensory afferents contacting monosynaptically α-motoneurons. The second one is the cholinergic input originating from V0c-interneurons, located in lamina X of the spinal cord, modulating activity of α-motoneurons via C-terminals. Our aim was to clarify whether enhancement of signaling to ankle extensor α-motoneurons, via direct electrical stimulation addressed predominantly to low-threshold proprioceptive fibers in the tibial nerve of awake rats, will affect Ia glutamatergic and cholinergic innervation of α-motoneurons of lateral gastrocnemius (LG). LG motoneurons were identified with True Blue tracer injected intramuscularly. Tibial nerve was stimulated for 7 days with continuous bursts of three pulses applied in four 20 min sessions daily. The Hoffmann reflex and motor responses recorded from the soleus muscle, LG synergist, allowed controlling stimulation. Ia terminals and C-terminals abutting on LG-labeled α-motoneurons were detected by immunofluorescence (IF) using input-specific anti- VGLUT1 and anti-VAChT antibodies, respectively. Quantitative analysis of confocal images revealed that the number of VGLUT1 IF and VAChT IF terminals contacting the soma of LG α-motoneurons increased after stimulation by 35% and by 26%, respectively, comparing to the sham-stimulated side. The aggregate volume of VGLUT1 IF and VAChT IF terminals increased by 35% and by 30%, respectively. Labeling intensity of boutons was also increased, suggesting an increase of signaling to LG α-motoneurons after stimulation. To conclude, one week of continuous burst stimulation of proprioceptive input to LG α-motoneurons is effective in enrichment of their direct glutamatergic but also indirect cholinergic inputs. The effectiveness of such and longer stimulation in models of injury is a

  8. Electrical Stimulation of Low-Threshold Proprioceptive Fibers in the Adult Rat Increases Density of Glutamatergic and Cholinergic Terminals on Ankle Extensor α-Motoneurons

    PubMed Central

    Gajewska-Woźniak, Olga; Grycz, Kamil; Czarkowska-Bauch, Julita; Skup, Małgorzata

    2016-01-01

    The effects of stimulation of low-threshold proprioceptive afferents in the tibial nerve on two types of excitatory inputs to α-motoneurons were tested. The first input is formed by glutamatergic Ia sensory afferents contacting monosynaptically α-motoneurons. The second one is the cholinergic input originating from V0c—interneurons, located in lamina X of the spinal cord, modulating activity of α-motoneurons via C-terminals. Our aim was to clarify whether enhancement of signaling to ankle extensor α-motoneurons, via direct electrical stimulation addressed predominantly to low-threshold proprioceptive fibers in the tibial nerve of awake rats, will affect Ia glutamatergic and cholinergic innervation of α-motoneurons of lateral gastrocnemius (LG). LG motoneurons were identified with True Blue tracer injected intramuscularly. Tibial nerve was stimulated for 7 days with continuous bursts of three pulses applied in four 20 min sessions daily. The Hoffmann reflex and motor responses recorded from the soleus muscle, LG synergist, allowed controlling stimulation. Ia terminals and C-terminals abutting on LG-labeled α-motoneurons were detected by immunofluorescence (IF) using input-specific anti- VGLUT1 and anti-VAChT antibodies, respectively. Quantitative analysis of confocal images revealed that the number of VGLUT1 IF and VAChT IF terminals contacting the soma of LG α-motoneurons increased after stimulation by 35% and by 26%, respectively, comparing to the sham-stimulated side. The aggregate volume of VGLUT1 IF and VAChT IF terminals increased by 35% and by 30%, respectively. Labeling intensity of boutons was also increased, suggesting an increase of signaling to LG α-motoneurons after stimulation. To conclude, one week of continuous burst stimulation of proprioceptive input to LG α-motoneurons is effective in enrichment of their direct glutamatergic but also indirect cholinergic inputs. The effectiveness of such and longer stimulation in models of injury is a

  9. Ankle replacement

    MedlinePlus

    Ankle arthroplasty - total; Total ankle arthroplasty; Endoprosthetic ankle replacement; Ankle surgery ... Ankle replacement surgery is most often done while you are under general anesthesia. This means you will ...

  10. Ankle arthroscopy

    MedlinePlus

    Ankle surgery; Arthroscopy - ankle; Surgery - ankle - arthroscopy; Surgery - ankle - arthroscopic ... You will likely receive general anesthesia before this surgery. This means you will be asleep and unable ...

  11. Ankle Problems

    MedlinePlus

    ... intense you're unable to walk on the ankle? Yes You may have a FRACTURE or a severe SPRAIN. Don't walk on the injured foot. Raise the leg and place ice on the swollen area. See your doctor promptly. No ... but you're still able to walk on the ankle? Yes You may have a SPRAINED ANKLE, or ...

  12. Comparative study on isokinetic capacity of knee and ankle joints by functional injury

    PubMed Central

    Jeon, Kyoungkyu; Seo, Byoung-Do; Lee, Sang-Ho

    2016-01-01

    [Purpose] To collect basic data for exercise programs designed to enhance functional knee and ankle joint stability based on isokinetic measurement and muscle strength evaluations in normal and impaired functional states. [Subjects and Methods] Twenty-four subjects were randomly assigned to the athlete group and the control group (n = 12 each). Data were collected of isokinetic knee extensor and flexor strength at 60°/sec, 180°/sec, and 240°/sec and ankle plantar and dorsiflexor strength at 30°/sec and 120°/sec. [Results] Significant intergroup differences were observed in peak torque of the right extensors at 60°/sec, 180°/sec, and 240°/sec and the right flexors at 240°/sec. Significant differences were observed in peak torque/body weight in the right extensors at 60°/sec, 180°/sec, and 240°/sec and in the right flexors at 180°/sec and 240°/sec. Significant peak torque differences were noted in the left ankle joint dorsiflexor at 30°/sec and 120°/sec, right plantar flexor at 120°/sec, left plantar flexor at 30°/sec, left dorsiflexor at 30°/sec and 120°/sec, and right dorsiflexor at 120°/sec. [Conclusion] Isokinetic evaluation stimulates muscle contraction at motion-dependent speeds and may contribute to the development of intervention programs to improve knee and ankle joint function and correct lower-extremity instability. PMID:26957768

  13. Synaptic Control of Motoneuronal Excitability

    PubMed Central

    Rekling, Jens C.; Funk, Gregory D.; Bayliss, Douglas A.; Dong, Xiao-Wei; Feldman, Jack L.

    2016-01-01

    Movement, the fundamental component of behavior and the principal extrinsic action of the brain, is produced when skeletal muscles contract and relax in response to patterns of action potentials generated by motoneurons. The processes that determine the firing behavior of motoneurons are therefore important in understanding the transformation of neural activity to motor behavior. Here, we review recent studies on the control of motoneuronal excitability, focusing on synaptic and cellular properties. We first present a background description of motoneurons: their development, anatomical organization, and membrane properties, both passive and active. We then describe the general anatomical organization of synaptic input to motoneurons, followed by a description of the major transmitter systems that affect motoneuronal excitability, including ligands, receptor distribution, pre- and postsynaptic actions, signal transduction, and functional role. Glutamate is the main excitatory, and GABA and glycine are the main inhibitory transmitters acting through ionotropic receptors. These amino acids signal the principal motor commands from peripheral, spinal, and supraspinal structures. Amines, such as serotonin and norepinephrine, and neuropeptides, as well as the glutamate and GABA acting at metabotropic receptors, modulate motoneuronal excitability through pre- and postsynaptic actions. Acting principally via second messenger systems, their actions converge on common effectors, e.g., leak K+ current, cationic inward current, hyperpolarization-activated inward current, Ca2+ channels, or presynaptic release processes. Together, these numerous inputs mediate and modify incoming motor commands, ultimately generating the coordinated firing patterns that underlie muscle contractions during motor behavior. PMID:10747207

  14. Ankle sprain (image)

    MedlinePlus

    An ankle sprain is a common injury to the ankle. The most common way the ankle is injured is when ... swelling, inflammation, and bruising around the ankle. An ankle sprain injury may take a few weeks to many ...

  15. A Novel Neuromuscular Electrical Stimulation Treatment for Recovery of Ankle Dorsiflexion in Chronic Hemiplegia

    PubMed Central

    Knutson, Jayme S.; Chae, John

    2011-01-01

    Objective To evaluate the feasibility of improving active ankle dorsiflexion with contralaterally controlled neuromuscular electrical stimulation (CCNMES). Design CCNMES dorsiflexes the paretic ankle with a stimulation intensity that is directly proportional to the degree of voluntary dorsiflexion of the unimpaired contralateral ankle, which is detected by an instrumented sock. Three subjects with chronic (>6-mo poststroke) dorsiflexor paresis participated in a 6-wk CCNMES treatment, which consisted of self-administering CCNMES-assisted ankle dorsiflexion exercises at home daily and practicing an ankle motor control task in the research laboratory twice a week. Results For subjects 1 and 2, respectively, maximum voluntary ankle dorsiflexion increased by 13 and 17 degrees, ankle movement tracking error decreased by ~57% and 57%, and lower limb Fugl-Meyer score (maximum score is 34) increased by 4 and 5 points. Subject 3 had no appreciable improvement in these measures. Both subjects 1 and 2 maintained their performance in ankle movement tracking through the 3-mo follow-up; subject 2 also maintained the gains in maximum ankle dorsiflexion and Fugl-Meyer score. Conclusions These results suggest that CCNMES may have a positive effect on ankle motor impairment in some stroke survivors. Further investigation of the effect of CCNMES on gait is warranted. PMID:20531158

  16. Ankle impingement.

    PubMed

    Lavery, Kyle P; McHale, Kevin J; Rossy, William H; Theodore, George

    2016-01-01

    Ankle impingement is a syndrome that encompasses a wide range of anterior and posterior joint pathology involving both osseous and soft tissue abnormalities. In this review, the etiology, pathoanatomy, diagnostic workup, and treatment options for both anterior and posterior ankle impingement syndromes are discussed. PMID:27608626

  17. Ankle Sprains

    MedlinePlus

    ... What's the Treatment for a Sprained Ankle? More Serious Sprains en español Esguinces de tobillo As a field hockey player, Jill was used to twisting her ankle. She'd always been able to walk it off and get back in the game. But one day she stepped on another player's ...

  18. Sprained Ankles

    MedlinePlus

    ... Body I think my child has sprained her ankle. How can I tell for sure? Sprains are injuries to the ligaments that connect bones ... away before the ligament is injured. Types of Sprains In young children, the ankle is the most commonly sprained joint, followed by ...

  19. Single motoneuron succinate dehydrogenase activity.

    PubMed

    Chalmers, G R; Edgerton, V R

    1989-07-01

    We have developed a quantitative histochemical assay for measurement of succinate dehydrogenase (SDH) activity in single motoneurons. A computer image processing system was used to quantify the histochemical enzyme reaction product and to follow the time course of the reaction. The optimal concentration for each of the ingredients of the incubation medium for the SDH reaction was determined and the importance of using histochemical "blanks" in the determination of enzymatic activity was demonstrated. The enzymatic activity was linear with respect to reaction time and tissue thickness. The procedure described meets the criteria generally considered essential for establishment of a quantitative histochemical assay. The assay was then used to examine the SDH activity of cat and rat motoneurons. It was found that motoneurons with a small soma size had a wide range of SDH activity, whereas those with a large soma size were restricted to low SDH activity. PMID:2732457

  20. Identification of intrinsic and reflex ankle stiffness components in stroke patients.

    PubMed

    Galiana, Laura; Fung, Joyce; Kearney, Robert

    2005-09-01

    Reflex and intrinsic contributions to ankle stiffness were examined in 11 stroke patients with clinical evidence of ankle spasticity and nine gender-matched and age-matched controls. Subjects lay supine with one foot placed in a custom-fitted boot attached to an electro-hydraulic actuator. They were instructed to relax while pseudo-random binary sequence perturbations were applied to their ankle joint. The ankle position and torque, as well as EMG from the ankle dorsiflexors and plantarflexors were recorded. These were used to identify reflex and intrinsic components of ankle stiffness, using a non-linear, parallel-cascade, system identification method. Results demonstrated that the majority of stroke patients (7/11) had ankle stiffness similar to that of control subjects. In contrast, a minority of stroke patients (4/11) had an abnormal increase in ankle stiffness, most of which could be attributed to an increased reflex gain. Reflex stiffness increased as the ankle was dorsiflexed in all subjects. These results differ from a previous study showing that reflex gain and intrinsic stiffness were increased in all patients with spinal cord injury. This difference may reflect the different topography of the lesions in the two neurological conditions. PMID:15991034

  1. Ankle and knee kinetics between strike patterns at common training speeds in competitive male runners.

    PubMed

    Kuhman, Daniel; Melcher, Daniel; Paquette, Max R

    2016-01-01

    The purpose of this study was to investigate the interaction of foot strike and common speeds on sagittal plane ankle and knee joint kinetics in competitive rear foot strike (RFS) runners when running with a RFS pattern and an imposed forefoot strike (FFS) pattern. Sixteen competitive habitual male RFS runners ran at two different speeds (i.e. 8 and 6 min mile(-1)) using their habitual RFS and an imposed FFS pattern. A repeated measures analysis of variance was used to assess a potential interaction between strike pattern and speed for selected ground reaction force (GRF) variables and, sagittal plane ankle and knee kinematic and kinetic variables. No foot strike and speed interaction was observed for any of the kinetic variables. Habitual RFS yielded a greater loading rate of the vertical GRF, peak ankle dorsiflexor moment, peak knee extensor moment, peak knee eccentric extensor power, peak dorsiflexion and sagittal plane knee range of motion compared to imposed FFS. Imposed FFS yielded greater maximum vertical GRF, peak ankle plantarflexor moment, peak ankle eccentric plantarflexor power and sagittal plane ankle ROM compared to habitual RFS. Consistent with previous literature, imposed FFS in habitual RFS reduces eccentric knee extensor and ankle dorsiflexor involvement but produce greater eccentric ankle plantarflexor action compared to RFS. These acute differences between strike patterns were independent of running speeds equivalent to typical easy and hard training runs in competitive male runners. Current findings along with previous literature suggest differences in lower extremity kinetics between habitual RFS and imposed FFS running are consistent among a variety of runner populations. PMID:26371382

  2. Ankle replacement

    MedlinePlus

    ... to the cut bony surfaces. A special glue/bone cement may be used to hold them in place. A piece of plastic is then inserted between the two metal parts. Screws maybe placed to stabilize your ankle. The surgeon ...

  3. Ankle sprain - Series (image)

    MedlinePlus

    The ankle joint connects the foot with the leg. The ankle joint allows the foot to move upward and ... outward motion. Muscles, tendons, and ligaments surround the ankle providing the stability the ankle joint needs for ...

  4. Improved ankle and knee control with a dual-channel functional electrical stimulation system in chronic hemiplegia. A case report.

    PubMed

    Springer, S; Khamis, S; Laufer, Y

    2014-04-01

    The aim of tis report is to describe the effects of a dual-channel functional electrical stimulation (FES) system applied daily as an orthotic device to the dorsiflexors and hamstrings muscles in a subject with chronic hemiparesis. Prior to the application of FES, the patient's gait was characterized by a footdrop and knee hyperextension during stance. measurements of gait performance were collected before FES application, after a conditioning period of six weeks, and following ten months of daily use. Outcomes included lower limb kinematics and temporal gait measures. The kinematic assessments indicated significant benefits for gait with the dorsiflexors and hamstrings FES, as compared to no stimulation and peroneal FES alone. In addition ot improved ankle control, knee hyperextension was reduced during stance, and the self-selected comfortable gait velocity increased following ten months of daily use. The results of this report suggest that dual-channel FES for the dorsiflexors and hamstrings muscles may affect ankle and knee control beyond that witch can be attributed to peroneal stimulation alone. The positive effects observed in this case study point to the potential of dual-channel FES as a viable treatment options in the rehabilitation of patients with similar impairments. PMID:24967447

  5. Adhesive capsulitis of the ankle (frozen ankle).

    PubMed

    van Moppes, F I; van den Hoogenband, C R; Greep, J M

    1979-09-01

    Adhesive capsulitis or "frozen ankle" is a syndrome resulting from repeated ankle sprains, or perhaps following immobilization after trauma. Ankle arthrography is a useful and safe diagnostic procedure in this syndrome. Typical arthrographic features are described together with case histories of two patients with frozen ankle. We suggest that early mobilization of the patient following trauma is particularly important in preventing the development of a forzen ankle syndrome. PMID:508071

  6. A portable powered ankle-foot orthosis for rehabilitation.

    PubMed

    Shorter, K Alex; Kogler, Géza F; Loth, Eric; Durfee, William K; Hsiao-Wecksler, Elizabeth T

    2011-01-01

    Innovative technological advancements in the field of orthotics, such as portable powered orthotic systems, could create new treatment modalities to improve the functional out come of rehabilitation. In this article, we present a novel portable powered ankle-foot orthosis (PPAFO) to provide untethered assistance during gait. The PPAFO provides both plantar flexor and dorsiflexor torque assistance by way of a bidirectional pneumatic rotary actuator. The system uses a portable pneumatic power source (compressed carbon dioxide bottle) and embedded electronics to control the actuation of the foot. We collected pilot experimental data from one impaired and three nondisabled subjects to demonstrate design functionality. The impaired subject had bilateral impairment of the lower legs due to cauda equina syndrome. We found that data from nondisabled walkers demonstrated the PPAFO's capability to provide correctly timed plantar flexor and dorsiflexor assistance during gait. Reduced activation of the tibialis anterior during stance and swing was also seen during assisted nondisabled walking trials. An increase in the vertical ground reaction force during the second half of stance was present during assisted trials for the impaired subject. Data from nondisabled walkers demonstrated functionality, and data from an impaired walker demonstrated the ability to provide functional plantar flexor assistance. PMID:21674394

  7. Motoneurons Derived from Induced Pluripotent Stem Cells Develop Mature Phenotypes Typical of Endogenous Spinal Motoneurons

    PubMed Central

    Toma, Jeremy S.; Shettar, Basavaraj C.; Chipman, Peter H.; Pinto, Devanand M.; Borowska, Joanna P.; Ichida, Justin K.; Fawcett, James P.; Zhang, Ying; Eggan, Kevin

    2015-01-01

    Induced pluripotent cell-derived motoneurons (iPSCMNs) are sought for use in cell replacement therapies and treatment strategies for motoneuron diseases such as amyotrophic lateral sclerosis (ALS). However, much remains unknown about the physiological properties of iPSCMNs and how they compare with endogenous spinal motoneurons or embryonic stem cell-derived motoneurons (ESCMNs). In the present study, we first used a proteomic approach and compared protein expression profiles between iPSCMNs and ESCMNs to show that <4% of the proteins identified were differentially regulated. Like ESCs, we found that mouse iPSCs treated with retinoic acid and a smoothened agonist differentiated into motoneurons expressing the LIM homeodomain protein Lhx3. When transplanted into the neural tube of developing chick embryos, iPSCMNs selectively targeted muscles normally innervated by Lhx3 motoneurons. In vitro studies showed that iPSCMNs form anatomically mature and functional neuromuscular junctions (NMJs) when cocultured with chick myofibers for several weeks. Electrophysiologically, iPSCMNs developed passive membrane and firing characteristic typical of postnatal motoneurons after several weeks in culture. Finally, iPSCMNs grafted into transected mouse tibial nerve projected axons to denervated gastrocnemius muscle fibers, where they formed functional NMJs, restored contractile force. and attenuated denervation atrophy. Together, iPSCMNs possess many of the same cellular and physiological characteristics as ESCMNs and endogenous spinal motoneurons. These results further justify using iPSCMNs as a source of motoneurons for cell replacement therapies and to study motoneuron diseases such as ALS. PMID:25609642

  8. Posthatching development of spinal motoneurons in the angelfish Pterophyllum scalare.

    PubMed

    Yoshida, M; Fudoji, M; Sakamoto, H; Uematsu, K

    1999-01-01

    We investigated the posthatching developmental sequence of spinal motoneurons innervating the axial muscles in the teleost angelfish, Pterophyllum scalare, by means of retrograde labeling with horseradish peroxidase. Two discrete types of spinal motoneurons, primary-type motoneurons and secondary motoneurons were labeled in a temporally different sequence during the course of larval development. These two types of motoneurons were morphologically distinguishable from one other. Primary-type motoneurons are generated by day 1 posthatching and do not increase in number over the observed period (to day 12 posthatching). In contrast, the secondary motoneurons increase in number through posthatching day 3. Differentiation of the spinal motoneurons appears to be nearly complete a few days before the onset of free swimming. In addition, the data suggest that the differentiation of secondary motoneurons precedes the development of the red muscle that is to be innervated by the motoneurons. PMID:10343084

  9. Effects of muscle strength asymmetry between left and right on isokinetic strength of the knee and ankle joints depending on athletic performance level

    PubMed Central

    Jeon, Kyoungkyu; Chun, Sungyung; Seo, Byoungdo

    2016-01-01

    [Purpose] The aim of this study was to collect basic data on the effect of asymmetry on the muscle strength of the left and right knee and ankle joints of soccer players at varying athletic performance levels, to guide the development of improved exercise programs. [Subjects and Methods] Forty-nine soccer players at three athletic performance levels participated: 15 professional, 16 amateur, and 18 college. Knee extensor and flexor strength were measured at 60°/sec and 180°/sec, and ankle plantar flexor and dorsiflexor strength were measured at 30°/sec and at 120°/sec. Variables were analyzed by one-way ANOVA. [Results] College soccer players showed greater muscle strength at 60°/sec and 180°/sec in the knee extension muscles of both the right and the left sides, lower muscle strength at 30°/sec and 120°/sec in the dorsiflexor of the right ankle, and similar levels of asymmetry between left and right. The maximum muscle strength on the same side significantly differed in the right ankle joint, with asymmetry between left and right at 30°/sec and 120°/sec. [Conclusion] These findings suggest that muscle strength asymmetry in the ankle joint may lead to counterbalancing muscle strengthening of the knee joint to maintain the center of body mass. PMID:27190469

  10. Effects of muscle strength asymmetry between left and right on isokinetic strength of the knee and ankle joints depending on athletic performance level.

    PubMed

    Jeon, Kyoungkyu; Chun, Sungyung; Seo, Byoungdo

    2016-04-01

    [Purpose] The aim of this study was to collect basic data on the effect of asymmetry on the muscle strength of the left and right knee and ankle joints of soccer players at varying athletic performance levels, to guide the development of improved exercise programs. [Subjects and Methods] Forty-nine soccer players at three athletic performance levels participated: 15 professional, 16 amateur, and 18 college. Knee extensor and flexor strength were measured at 60°/sec and 180°/sec, and ankle plantar flexor and dorsiflexor strength were measured at 30°/sec and at 120°/sec. Variables were analyzed by one-way ANOVA. [Results] College soccer players showed greater muscle strength at 60°/sec and 180°/sec in the knee extension muscles of both the right and the left sides, lower muscle strength at 30°/sec and 120°/sec in the dorsiflexor of the right ankle, and similar levels of asymmetry between left and right. The maximum muscle strength on the same side significantly differed in the right ankle joint, with asymmetry between left and right at 30°/sec and 120°/sec. [Conclusion] These findings suggest that muscle strength asymmetry in the ankle joint may lead to counterbalancing muscle strengthening of the knee joint to maintain the center of body mass. PMID:27190469

  11. The effect of ankle joint muscle strengthening training and static muscle stretching training on stroke patients' C.o.p sway amplitude.

    PubMed

    Kim, Tae Ho; Yoon, Joo Soo; Lee, Jin Hwan

    2013-12-01

    [Purpose] This study implement ankle joint dorsiflexion training for ankle muscle the weakness that impairs stroke patients' gait performance, to examine the effect of the training on stroke patients' plantar pressure and gait ability. [Subjects and Methods] In this study, 36 stroke patients diagnosed with stroke due to cerebral infarction or cerebral hemorrhage performed the training. Static muscle stretching was performed four times a week for 20 minutes at a time for 6 weeks by the training group. Ankle dorsiflexor training was performed four times a week, two sets per time in the case of females and three sets per time in the case of males for 6 weeks, by another group. Center of pressure sway amplitude was measured using the F-scan system during gait. All subjects were assessed with the same measurements at a pre-study examination and reassessed at eight weeks. Data were analyzed statistically using the paired t-test and one-way ANOVA. [Results] Among the between ankle dorsiflexor training group, static muscle stretching group, and control group, the difference before and after the training were proven to be statistically significant. [Conclusion] Compared to other training groups, the ankle muscle strength training group showed statistically significant increases of forward thrust at stroke patients' toe-off which positively affected stroke patients' ability to perform gait. PMID:24409032

  12. Shank Muscle Strength Training Changes Foot Behaviour during a Sudden Ankle Supination

    PubMed Central

    Hagen, Marco; Lescher, Stephanie; Gerhardt, Andreas; Lahner, Matthias; Felber, Stephan; Hennig, Ewald M.

    2015-01-01

    Background The peroneal muscles are the most effective lateral stabilisers whose tension braces the ankle joint complex against excessive supination. The purpose of this study was to identify the morphological and biomechanical effects of two machine-based shank muscle training methods. Methods Twenty-two healthy male recreationally active sports students performed ten weeks of single-set high resistance strength training with 3 training sessions per week. The subjects conducted subtalar pronator/supinator muscle training (ST) with the right leg by using a custom-made apparatus; the left foot muscles were exercised with machine-based talocrural plantar and dorsiflexor training (TT). Muscle strength (MVIC), muscle volume and foot biomechanics (rearfoot motion, ground reaction forces, muscle reaction times) during a sudden ankle supination were recorded before and after the intervention. Results Compared to TT, ST resulted in significantly higher pronator (14% vs. 8%, P<0.01) and supinator MVIC (25% vs. 12%, P<0.01). During sudden foot inversions, both ST and TT resulted in reduced supination velocity (-12%; P<0.01). The muscle reaction onset time was faster after the training in peroneus longus (PL) (P<0.01). Muscle volume of PL (P<0.01) and TA (P<0.01) increased significantly after both ST and TT. Conclusion After both ST and TT, the ankle joint complex is mechanically more stabilised against sudden supinations due to the muscle volume increase of PL and TA. As the reduced supination velocities indicate, the strength training effects are already present during free-fall. According to a sudden ankle supination in standing position, both machine-based dorsiflexor and pronator strength training is recommended for enhancing the mechanical stability of the ankle. PMID:26110847

  13. Adaptability of the oxidative capacity of motoneurons

    NASA Technical Reports Server (NTRS)

    Chalmers, G. R.; Roy, R. R.; Edgerton, V. R.

    1992-01-01

    Previous studies have demonstrated that a chronic change in neuronal activation can produce a change in soma oxidative capacity, suggesting that: (i) these 2 variables are directly related in neurons and (ii) ion pumping is an important energy requiring activity of a neuron. Most of these studies, however, have focused on reduced activation levels of sensory systems. In the present study the effect of a chronic increase or decrease in motoneuronal activity on motoneuron oxidative capacity and soma size was studied. In addition, the effect of chronic axotomy was studied as an indicator of whether cytoplasmic volume may also be related to the oxidative capacity of motoneurons. A quantitative histochemical assay for succinate dehydrogenase activity was used as a measure of motoneuron oxidative capacity in experimental models in which chronic electromyography has been used to verify neuronal activity levels. Spinal transection reduced, and spinal isolation virtually eliminated lumbar motoneuron electrical activity. Functional overload of the plantaris by removal of its major synergists was used to chronically increase neural activity of the plantaris motor pool. No change in oxidative capacity or soma size resulted from either a chronic increase or decrease in neuronal activity level. These data indicate that the chronic modulation of ionic transport and neurotransmitter turnover associated with action potentials do not induce compensatory metabolic responses in the metabolic capacity of the soma of lumbar motoneurons. Soma oxidative capacity was reduced in the axotomized motoneurons, suggesting that a combination of axoplasmic transport, intracellular biosynthesis and perhaps neurotransmitter turnover represent the major energy demands on a motoneuron. While soma oxidative capacity may be closely related to neural activity in some neural systems, e.g. visual and auditory, lumbar motoneurons appear to be much less sensitive to modulations in chronic activity levels.

  14. Experimental evaluation of a portable powered ankle-foot orthosis.

    PubMed

    Shorter, Kenneth A; Li, Yifan; Morris, Emily A; Kogler, Géza F; Hsiao-Wecksler, Elizabeth T

    2011-01-01

    Ankle-foot orthoses (AFOs) ameliorate the impact of impairments to the lower limb neuromuscular motor system that affect gait. Emerging technologies provide a vision for fully powered, untethered AFOs. The portable powered AFO (PPAFO) provides both plantarflexor and dorsiflexor torque assistance via a bi-directional pneumatic rotary actuator. The system uses a portable pneumatic power source (bottle of compressed CO(2)) and embedded electronics to control foot motion during level walking. Experimental data were collected to demonstrate functionality from two subjects with bilateral impairments to the lower legs. These data demonstrated the PPAFO's ability to provide functional assistance during gait. The stringent design requirements of light weight, small size, high efficiency and low noise make the creation of daily wear assist devices challenging; but once such devices appear, they will present new opportunities for clinical treatment of gait abnormalities. PMID:22254386

  15. Unique Positioning for Using Elastic Resistance Band in Providing Strengthening Exercise to the Muscles Surrounding the Ankle

    PubMed Central

    Bandy, William D.

    2007-01-01

    Ankle sprains are among the most common injuries incurred by participants in athletics. Conservative management of the patient after an ankle sprain includes a comprehensive rehabilitation program of which the resistance exercises are a part and are frequently advised by the clinician, many times as part of a home exercise program. The purpose of this Clinical Suggestion is to present a unique method of using elastic resistance band to provide strengthening activities to the inverters, ever-tors, plantarflexors, and dorsiflexors of the ankle. The method is unique, as well as convenient and efficient, as it allows the subject to perform all four exercises with a minimum of change in position, while staying seated in a chair. PMID:21522203

  16. Effect of ankle proprioceptive training on static body balance.

    PubMed

    Karakaya, Mehmet Gürhan; Rutbİl, Hilal; Akpinar, Ercan; Yildirim, Alİ; Karakaya, İlkİm Çitak

    2015-10-01

    [Purpose] This study aimed to investigate the effect of ankle proprioceptive training on static body balance. [Subjects and Methods] In this randomized-controlled, single-blind study, 59 university students (35 females, 24 males) were randomized into study (n=29) and control (n=30) groups. The study group received a foot and ankle proprioceptive exercise program including stretching, strengthening (plantar and dorsi-flexors, invertor and evertor muscles), and balance board exercises, each with 10 repetitions per session, 5 days a week, for a total of 10 sessions. The control group did not receive any intervention. Static body balance was evaluated by a kinesthetic ability trainer, which showed the balance index scores under both single foot and both feet conditions. This evaluation was repeated at the end of two weeks for both groups. [Results] Outcome measures of the groups were similar at the baseline. Balance index scores of both groups improved at the end of two weeks, and the study group had significantly lower index scores than those of the control group, indicating better balance. [Conclusion] Ankle proprioceptive training had positive effects on static body balance parameters in healthy individuals, and it is worth investigating the effects of this type of training in patients with balance disorders. PMID:26644697

  17. Fatigability of the dorsiflexors and associations among multiple domains of motor function in young and old adults

    PubMed Central

    Justice, Jamie N.; Mani, Diba; Pierpoint, Lauren A.; Enoka, Roger M.

    2014-01-01

    Declines in neuromuscular function, including measures of mobility, muscle strength, steadiness, and patterns of muscle activation, accompany advancing age and are often associated with reduced quality of life and mortality. Paradoxically, older adults are less fatigable than young adults in some tasks. The purpose of this study was to determine the influence of age on fatigability of the dorsiflexors and to evaluate the ecological validity of this test by comparing it to motor function subdomains known to decline with advancing age. The community-dwelling older adults (n = 52, 75.2 ± 6.0 years) were more fatigable than young adults (n = 26, 22.2 ± 3.7 years), as assessed by endurance time for supporting a submaximal load (20% of one-repetition maximum; 1-RM) with an isometric contraction of the dorsiflexor muscles (8.9 ± 0.6 min and 15.5 ± 0.9 min, p < 0.001), including participants matched for 1-RM load and sex (Y: 13.3 ± 4.0 min, O: 8.5 ± 6.1 min, n = 11 pairs, 6 women, p < 0.05). When the older adults were separated into two groups (65-75 and 76-90 yrs), however, only endurance time for the oldest group was less than that for the other two groups (p < 0.01). All measures of motor function were significantly correlated (all p < 0.05) with dorsiflexor endurance time for the older adults, and multiple regression analysis revealed that the variance in endurance time was most closely associated with age, steadiness, and knee flexor strength (R2 = 0.50, p < 0.001). These findings indicate that dorsiflexor fatigability provides a valid biomarker of motor function in older adults. PMID:24703888

  18. Intracellular autogenetic and synergistic effects of muscular contraction on flexor motoneurones

    PubMed Central

    Green, D. G.; Kellerth, J.-O.

    1967-01-01

    1. Intracellular records have been taken from cat motoneurones innervating flexor muscles of the hind limb. Contractions of the ankle flexors tibialis anterior and extensor digitorum longus were elicited by stimulation of the peripheral end of the cut L 7 ventral root and the reflex effects of these contractions were recorded in silent and repetitively firing motoneurones. 2. Contraction usually produces a hyperpolarizing response inside flexor motoneurones. This hyperpolarization is tension-sensitive in the sense that when, at constant muscle extension, the strength of the contraction is increased, the magnitude of the inhibitory response is augmented. 3. Increasing the resting length of the muscles, while using a stimulus of constant strength to the ventral root, causes this inhibitory response to increase in some cells. More often, however, the hyperpolarization caused by contraction is gradually reduced in duration and/or amplitude as the muscles are extended. 4. Even with the muscles slackened, so that they develop no tension at their ends, contraction usually produces prominent hyperpolarization of the motoneurones. 5. By passing polarizing currents or injecting chloride ions through the intracellular micro-electrode, the hyperpolarizing potentials produced by contraction of the slack and extended muscles are shown to be, at least in part, genuinely post-synaptic inhibitory events. 6. When the neurone is fired repetitively by injected current, the `silent period' in contraction corresponds to the hyperpolarization of the post-synaptic membrane. 7. Monosynaptic testing of the flexor motoneurone pool has been used to confirm the essential features of the intracellularly recorded activity. 8. Acutely spinalizing the animal increases the magnitude of the inhibitory responses caused by contraction. 9. Recordings from dorsal root fibres show that Golgi tendon organs of the ankle flexors are very sensitive to contraction and are indeed often activated by the

  19. Hypocretinergic control of spinal cord motoneurons.

    PubMed

    Yamuy, Jack; Fung, Simon J; Xi, Mingchu; Chase, Michael H

    2004-06-01

    Hypocretinergic (orexinergic) neurons in the lateral hypothalamus project to motor columns in the lumbar spinal cord. Consequently, we sought to determine whether the hypocretinergic system modulates the electrical activity of motoneurons. Using in vivo intracellular recording techniques, we examined the response of spinal motoneurons in the cat to electrical stimulation of the lateral hypothalamus. In addition, we examined the membrane potential response to orthodromic stimulation and intracellular current injection before and after both hypothalamic stimulation and the juxtacellular application of hypocretin-1. It was found that (1) hypothalamic stimulation produced a complex sequence of depolarizing- hyperpolarizing potentials in spinal motoneurons; (2) the depolarizing potentials decreased in amplitude after the application of SB-334867, a hypocretin type 1 receptor antagonist; (3) the EPSP induced by dorsal root stimulation was not affected by the application of SB-334867; (4) subthreshold stimulation of dorsal roots and intracellular depolarizing current steps produced spike potentials when applied in concert to stimulation of the hypothalamus or after the local application of hypocretin-1; (5) the juxtacellular application of hypocretin-1 induced motoneuron depolarization and, frequently, high-frequency discharge; (6) hypocretin-1 produced a significant decrease in rheobase (36%), membrane time constant (16.4%), and the equalizing time constant (23.3%); (7) in a small number of motoneurons, hypocretin-1 produced an increase in the synaptic noise; and (8) the input resistance was not affected after hypocretin-1. The juxtacellular application of vehicle (saline) and denatured hypocretin-1 did not produce changes in the preceding electrophysiological properties. We conclude that hypothalamic hypocretinergic neurons are capable of modulating the activity of lumbar motoneurons through presynaptic and postsynaptic mechanisms. The lack of hypocretin

  20. Identification of common excitatory motoneurons in Drosophila melanogaster larvae.

    PubMed

    Takizawa, Eiji; Komatsu, Akira; Tsujimura, Hidenobu

    2007-05-01

    In insects, four types of motoneurons have long been known, including fast motoneurons, slow motoneurons, common inhibitory motoneurons, and DUM neurons. They innervate the same muscle and control its contraction together. Recent studies in Drosophila have suggested the existence of another type of motoneuron, the common excitatory motoneuron. Here, we found that shakB-GAL4 produced by labels this type of motoneuron in Drosophila larvae. We found that Drosophila larvae have two common excitatory motoneurons in each abdominal segment, RP2 for dorsal muscles and MNSNb/d-Is for ventral muscles. They innervate most of the internal longitudinal or oblique muscles on the dorsal or ventral body wall with type-Is terminals and use glutamate as a transmitter. Electrophysiological recording indicated that stimulation of the RP2 axon evoked excitatory junctional potential in a dorsal muscle. PMID:17867850

  1. Development of an efficient rehabilitation exercise program for functional recovery in chronic ankle instability

    PubMed Central

    Kim, Kewwan; Jeon, Kyoungkyu

    2016-01-01

    [Purpose] The aim of the present study was to construct an integrated rehabilitation exercise program to prevent chronic pain and improve motor ability in cases of ankle injury and re-injury. [Subjects and Methods] Twenty-six male soccer players who required functional strength exercises due to repeated ankle injury were the subjects. A 12-week rehabilitation exercise program was constructed with the aim of improving muscle strength in the ankle and dynamic coordination of the lower limb. Muscle strength and dynamic coordination were evaluated using the Y Balance Test, and isokinetic muscle strength of ankle dorsiflexion, plantarflexion, inversion, and eversion were measured before and after the 12-week program. [Results] Following 12 weeks of rehabilitation exercise, there were statistically significant improvements in the ratios of dorsiflexor strength to plantarflexor strength, eversion strength, and inversion strength on the left side. The other variables showed no significant changes. [Conclusion] The rehabilitation exercise program for chronic ankle instability helped to reduce pain, and to restore normal joint range of motion, muscle strength and endurance, and functional ability. Active protocols to improve complex functions need to be developed to complement these results. PMID:27313347

  2. Determination of ankle muscle power in normal gait using an EMG-to-force processing approach.

    PubMed

    Bogey, R A; Gitter, A J; Barnes, L A

    2010-02-01

    The purpose of this study was to determine the contribution of individual ankle muscles to the net ankle power and to examine each muscle's role in propulsion or support of the body during normal, self-selected-speed walking. An EMG-to-force processing (EFP) model was developed which scaled muscle tendon unit force output to gait EMG, with that muscle's power output being the product of muscle force and contraction velocity. Net EFP power was determined by summing individual ankle muscle power. Net ankle power was also calculated for these subjects via inverse dynamics. Closeness of fit of the power curves of the two methods was used to validate the model. The curves were highly correlated (r(2)=.91), thus the model was deconstructed to analyze the power contribution and role of each ankle muscle during normal gait. Key findings were that the plantar flexors control tibial rotation in single support, and act to propel the entire limb into swing phase. The dorsiflexors provide positive power for swing phase foot clearance, negative power to control early stance phase foot placement, and a second positive power burst to actively advance the tibia in the transition from double to single support. Co-contraction of agonists and antagonists was limited to only a small percentage of the gait cycle. PMID:19201619

  3. Effects of Strength Training on Strength Development and Joint Position Sense in Functionally Unstable Ankles

    PubMed Central

    Docherty, Carrie L.; Moore, Josef H.; Arnold, Brent L.

    1998-01-01

    Objective: To examine the effects of ankle-strengthening exercises on joint position sense and strength development in subjects with functionally unstable ankles. Design and Setting: Subjects were randomly assigned to a training or control group. The training group participated in a 6-week strength-training protocol using rubber tubing 3 times a week throughout the training period. The control group did not participate in the strength-training protocol. Subjects: Twenty healthy college students (10 females, 10 males, age = 20.6 ± 2.23 years; ht = 176.40 ± 7.14 cm; wt = 74.18 ± 10.17 kg) with a history of functional ankle instability volunteered to participate in this study. Measurements: We pretested and posttested dorsiflexor and evertor isometric strength with a handheld dynamometer and collected joint position sense (JPS) data at 20° for inversion and plantar flexion and at 10° for eversion and dorsiflexion. Results: Statistical tests for strength and JPS revealed significant group-by-time interactions for dorsiflexion strength, eversion strength, inversion JPS, and plantar flexion JPS. Simple main-effects testing revealed improvements in training group strength and JPS at posttesting. There were no significant effects for eversion JPS, but the group main effect for dorsiflexion JPS was significant, with the experimental group having better scores than the control group. Conclusions: Ankle-strengthening exercises improved strength, inversion JPS, dorsiflexion JPS, and plantar flexion JPS in subjects with functionally unstable ankles. Imagesp311-a PMID:16558526

  4. Development of an efficient rehabilitation exercise program for functional recovery in chronic ankle instability.

    PubMed

    Kim, Kewwan; Jeon, Kyoungkyu

    2016-05-01

    [Purpose] The aim of the present study was to construct an integrated rehabilitation exercise program to prevent chronic pain and improve motor ability in cases of ankle injury and re-injury. [Subjects and Methods] Twenty-six male soccer players who required functional strength exercises due to repeated ankle injury were the subjects. A 12-week rehabilitation exercise program was constructed with the aim of improving muscle strength in the ankle and dynamic coordination of the lower limb. Muscle strength and dynamic coordination were evaluated using the Y Balance Test, and isokinetic muscle strength of ankle dorsiflexion, plantarflexion, inversion, and eversion were measured before and after the 12-week program. [Results] Following 12 weeks of rehabilitation exercise, there were statistically significant improvements in the ratios of dorsiflexor strength to plantarflexor strength, eversion strength, and inversion strength on the left side. The other variables showed no significant changes. [Conclusion] The rehabilitation exercise program for chronic ankle instability helped to reduce pain, and to restore normal joint range of motion, muscle strength and endurance, and functional ability. Active protocols to improve complex functions need to be developed to complement these results. PMID:27313347

  5. Factors influencing the spinal motoneurons in development

    PubMed Central

    Wiese, Stefan

    2015-01-01

    The development of the spinal cord needs a concerted interaction of transcription factors activating diverse genes and signals from outside acting on the specification of the different cells. Signals have to act on the segments of the embryo as well as on the cranial-caudal axis and the dorso-ventral axis. Additionally the axons of the motoneurons have to cross the central nervous system barrier to connect to the periphery. Intensive anatomical studies have been followed by molecular characterization of the different subsets of transcription factors that are expressed by cells of the developing spinal cord. Here, intensive studies for the most important appearing cells, the motoneurons, have resulted in a good knowledge on the expression patterns of these proteins. Nonetheless motoneurons are by far not the only important cells and the concert activity of all cells besides them is necessary for the correct function and integrity of motoneurons within the spinal cord. This article will briefly summarize the different aspects on spinal cord development and focuses on the differentiation as well as the functionalization of motoneurons. PMID:26807112

  6. Ankle sprain - slideshow

    MedlinePlus

    ... this page: //medlineplus.gov/ency/presentations/100209.htm Ankle sprain - Series To use the sharing features on ... 4 out of 4 Normal anatomy Overview The ankle joint connects the foot with the leg. The ...

  7. Skin Cooling and Force Replication at the Ankle in Healthy Individuals: A Crossover Randomized Controlled Trial

    PubMed Central

    Haupenthal, Daniela Pacheco dos Santos; de Noronha, Marcos; Haupenthal, Alessandro; Ruschel, Caroline; Nunes, Guilherme S.

    2015-01-01

    Context Proprioception of the ankle is determined by the ability to perceive the sense of position of the ankle structures, as well as the speed and direction of movement. Few researchers have investigated proprioception by force-replication ability and particularly after skin cooling. Objective To analyze the ability of the ankle-dorsiflexor muscles to replicate isometric force after a period of skin cooling. Design Randomized controlled clinical trial. Setting Laboratory. Patients or Other Participants Twenty healthy individuals (10 men, 10 women; age = 26.8 ± 5.2 years, height = 171 ± 7 cm, mass = 66.8 ± 10.5 kg). Intervention(s) Skin cooling was carried out using 2 ice applications: (1) after maximal voluntary isometric contraction (MVIC) performance and before data collection for the first target force, maintained for 20 minutes; and (2) before data collection for the second target force, maintained for 10 minutes. We measured skin temperature before and after ice applications to ensure skin cooling. Main Outcome Measure(s) A load cell was placed under an inclined board for data collection, and 10 attempts of force replication were carried out for 2 values of MVIC (20%, 50%) in each condition (ice, no ice). We assessed force sense with absolute and root mean square errors (the difference between the force developed by the dorsiflexors and the target force measured with the raw data and after root mean square analysis, respectively) and variable error (the variance around the mean absolute error score). A repeated-measures multivariate analysis of variance was used for statistical analysis. Results The absolute error was greater for the ice than for the no-ice condition (F1,19 = 9.05, P = .007) and for the target force at 50% of MVIC than at 20% of MVIC (F1,19 = 26.01, P < .001). Conclusions The error was greater in the ice condition and at 50% of MVIC. Skin cooling reduced the proprioceptive ability of the ankle-dorsiflexor muscles to replicate isometric

  8. Ankle Injuries and Disorders

    MedlinePlus

    Your ankle bone and the ends of your two lower leg bones make up the ankle joint. Your ligaments, which connect bones to one ... muscles and tendons move it. The most common ankle problems are sprains and fractures. A sprain is ...

  9. Assessment of Ankle Injuries

    ERIC Educational Resources Information Center

    Mai, Nicholas; Cooper, Leslie

    2009-01-01

    School nurses are faced with the challenge of identifying and treating ankle injuries in the school setting. There is little information guiding the assessment and treatment of these children when an injury occurs. It is essential for school nurses to understand ankle anatomy, pathophysiology of the acute ankle injury, general and orthopedic…

  10. Arthroscopic Ankle Arthrodesis.

    PubMed

    Hutchinson, Byron

    2016-10-01

    Arthroscopic ankle arthrodesis is a cost-effective option for many patients with posttraumatic arthritis of the ankle joint. Rehabilitation is generally quicker than conventional open techniques, and rates of fusion are comparable or better than traditional open techniques. Unless the arthroscopic surgeon has considerable experience, the best results are seen in patients with very little deformity in the ankle joint. PMID:27599442

  11. Testing the excitability of human motoneurons

    PubMed Central

    McNeil, Chris J.; Butler, Jane E.; Taylor, Janet L.; Gandevia, Simon C.

    2013-01-01

    The responsiveness of the human central nervous system can change profoundly with exercise, injury, disuse, or disease. Changes occur at both cortical and spinal levels but in most cases excitability of the motoneuron pool must be assessed to localize accurately the site of adaptation. Hence, it is critical to understand, and employ correctly, the methods to test motoneuron excitability in humans. Several techniques exist and each has its advantages and disadvantages. This review examines the most common techniques that use evoked compound muscle action potentials to test the excitability of the motoneuron pool and describes the merits and limitations of each. The techniques discussed are the H-reflex, F-wave, tendon jerk, V-wave, cervicomedullary motor evoked potential (CMEP), and motor evoked potential (MEP). A number of limitations with these techniques are presented. PMID:23630483

  12. Evidence for reversible motoneurone dysfunction in thyrotoxicosis

    PubMed Central

    McComas, A. J.; Sica, R. E. P.; McNabb, A. R.; Goldberg, W. M.; Upton, A. R. M.

    1974-01-01

    Motor unit estimating techniques have been employed as part of a comprehensive electrophysiological survey of peripheral nerve and muscle in 20 patients with thyrotoxicosis. In all patients there was evidence of a loss of operational motor units; the selective nature of this involvement suggested that the motoneurone soma was the site of the primary lesion. The reversible nature of the postulated motoneurone dysfunction was demonstrated by the increased motor unit counts in six patients who were studied again after treatment of their thyrotoxicosis. PMID:4836749

  13. The sprained ankle.

    PubMed

    Puffer, J C

    2001-01-01

    The sprained ankle is the most common musculoskeletal injury seen by physicians caring for active youngsters and adults. It accounts for approximately one fourth of all sports-related injuries and is commonly seen in athletes participating in basketball, soccer, or football. It has been shown that one third of West Point cadets suffer an ankle sprain during their 4 years at the military academy. While diagnosis and management of the sprained ankle is usually straightforward, several serious injuries can masquerade as an ankle sprain, and it is important for the clinician to recognize these to prevent long-term morbidity. In this article the basic anatomy of the ankle, mechanisms by which the ankle is injured, and the differential diagnosis of the acutely injured ankle are reviewed. Appropriate evaluation of the injured ankle and the criteria that should be utilized for determining the necessity of radiographs are discussed as well as management of the acutely sprained ankle and the role of prevention in reducing the risk of ankle injury. PMID:11464730

  14. Balance in single-limb stance after surgically treated ankle fractures: a 14-month follow-up

    PubMed Central

    Nilsson, Gertrud; Ageberg, Eva; Ekdahl, Charlotte; Eneroth, Magnus

    2006-01-01

    Background The maintenance of postural control is fundamental for different types of physical activity. This can be measured by having subjects stand on one leg on a force plate. Many studies assessing standing balance have previously been carried out in patients with ankle ligament injuries but not in patients with ankle fractures. The aim of this study was to evaluate whether patients operated on because of an ankle fracture had impaired postural control compared to an uninjured age- and gender-matched control group. Methods Fifty-four individuals (patients) operated on because of an ankle fracture were examined 14 months postoperatively. Muscle strength, ankle mobility, and single-limb stance on a force-platform were measured. Average speed of centre of pressure movements and number of movements exceeding 10 mm from the mean value of centre of pressure were registered in the frontal and sagittal planes on a force-platform. Fifty-four age- and gender-matched uninjured individuals (controls) were examined in the single-limb stance test only. The paired Student t-test was used for comparisons between patients' injured and uninjured legs and between side-matched legs within the controls. The independent Student t-test was used for comparisons between patients and controls. The Chi-square test, and when applicable, Fisher's exact test were used for comparisons between groups. Multiple logistic regression was performed to identify factors associated with belonging to the group unable to complete the single-limb stance test on the force-platform. Results Fourteen of the 54 patients (26%) did not manage to complete the single-limb stance test on the force-platform, whereas all controls managed this (p < 0.001). Age over 45 years was the only factor significantly associated with not managing the test. When not adjusted for age, decreased strength in the ankle plantar flexors and dorsiflexors was significantly associated with not managing the test. In the 40 patients who

  15. Ankle Sprains. A Round Table.

    ERIC Educational Resources Information Center

    Physician and Sportsmedicine, 1986

    1986-01-01

    Types of ankle sprains, surgical versus nonsurgical treatment, tape versus brace for support, rehabilitation, exercise, and prevention of ankle sprains are discussed by a panel of experts. An acute ankle taping technique is illustrated. (MT)

  16. Foot, leg, and ankle swelling

    MedlinePlus

    Swelling of the ankles - feet - legs; Ankle swelling; Foot swelling; Leg swelling; Edema - peripheral; Peripheral edema ... Foot, leg, and ankle swelling is common when the person also: Is overweight Has a blood clot in the leg Is older Has ...

  17. Ankle Fractures Often Not Diagnosed

    MedlinePlus

    ... News, Videos & Podcasts » Articles » Text Size Print Bookmark Ankle Fractures Often Not Diagnosed Long-term Complications Result from Poor Recovery Mistaking an ankle fracture for an ankle sprain has serious consequences ...

  18. Androgenic, But Not Estrogenic, Protection of Motoneurons from Somal and Dendritic Atrophy Induced by the Death of Neighboring Motoneurons

    PubMed Central

    Fargo, Keith N.; Sengelaub, Dale R.

    2009-01-01

    Motoneuron loss is a significant medical problem, capable of causing severe movement disorders or even death. We have been investigating the effects of motoneuron loss on surviving motoneurons in a lumbar motor nucleus, the spinal nucleus of the bulbocavernosus (SNB). SNB motoneurons undergo marked dendritic and somal atrophy following the experimentally induced death of other nearby SNB motoneurons. However, treatment with testosterone at the time of lesioning attenuates this atrophy. Because testosterone can be metabolized into the estrogen estradiol (as well as other physiologically active steroid hormones), it was unknown whether the protective effect of testosterone was an androgen effect, an estrogen effect, or both. In the present experiment, we used a retrogradely transported neurotoxin to kill the majority of SNB motoneurons on one side of the spinal cord only in adult male rats. Some animals were also treated with either testosterone, the androgen dihydrotestosterone (which cannot be converted into estradiol), or the estrogen estradiol. As seen previously, partial motoneuron loss led to reductions in soma area and in dendritic length and extent in surviving motoneurons. Testosterone and dihydrotestosterone attenuated these reductions, but estradiol had no protective effect. These results indicate that the neuroprotective effect of testosterone on the morphology of SNB motoneurons following partial motoneuron depletion is an androgen effect rather than an estrogen effect. PMID:17565709

  19. Neuroprotective effects of testosterone on the morphology and function of somatic motoneurons following the death of neighboring motoneurons

    PubMed Central

    Little, Christine M.; Coons, Kellie D.; Sengelaub, Dale R.

    2008-01-01

    Motoneuron loss is a significant medical problem, capable of causing severe movement disorders or even death. We have previously shown that partial depletion of motoneurons from sexually dimorphic, highly androgen-sensitive spinal motor populations induces dendritic atrophy in remaining motoneurons, and this atrophy is attenuated by treatment with testosterone. To test whether testosterone has similar effects in more typical motoneurons, we examined potential neuroprotective effects in motoneurons innervating muscles of the quadriceps. Motoneurons innervating the vastus medialis muscle were selectively killed by intramuscular injection of cholera toxin-conjugated saporin. Simultaneously, some saporin-injected rats were given implants containing testosterone or left untreated. Four weeks later, motoneurons innervating the ipsilateral vastus lateralis muscle were labeled with cholera toxin-conjugated HRP, and dendritic arbors were reconstructed in 3 dimensions. Compared to intact normal males, partial motoneuron depletion resulted in decreased dendritic length in remaining quadriceps motoneurons, and this atrophy was attenuated by testosterone treatment. To examine the functional consequences of the induced dendritic atrophy, and its attenuation with testosterone treatment, the activation of remaining quadriceps motoneurons was assessed using peripheral nerve recording. Partial motoneuron depletion resulted in decreased amplitudes of motor nerve activity, and these changes were attenuated by treatment with testosterone, providing a functional correlate to the neuroprotective effects of testosterone treatment on quadriceps motoneuron morphology. Together, these findings suggest that testosterone has neuroprotective effects on morphology and function in both highly androgen-sensitive as well as more typical motoneuron populations, further supporting a role for testosterone as a neurotherapeutic agent in the injured nervous system. PMID:19003970

  20. How to Care for a Sprained Ankle

    MedlinePlus

    ... Sprained Ankle How to Care for a Sprained Ankle Page Content Ankle sprains are very common injuries. ... Grade I, II or III. Treating your Sprained Ankle Treating your sprained ankle properly may prevent chronic ...

  1. Motoneurons are essential for vascular pathfinding

    PubMed Central

    Lim, Amy H.; Suli, Arminda; Yaniv, Karina; Weinstein, Brant; Li, Dean Y.; Chien, Chi-Bin

    2011-01-01

    The neural and vascular systems share common guidance cues that have direct and independent signaling effects on nerves and endothelial cells. Here, we show that zebrafish Netrin 1a directs Dcc-mediated axon guidance of motoneurons and that this neural guidance function is essential for lymphangiogenesis. Specifically, Netrin 1a secreted by the muscle pioneers at the horizontal myoseptum (HMS) is required for the sprouting of dcc-expressing rostral primary motoneuron (RoP) axons and neighboring axons along the HMS, adjacent to the future trajectory of the parachordal chain (PAC). These axons are required for the formation of the PAC and, subsequently, the thoracic duct. The failure to form the PAC in netrin 1a or dcc morphants is phenocopied by laser ablation of motoneurons and is rescued both by cellular transplants and overexpression of dcc mRNA. These results provide a definitive example of the requirement of axons in endothelial guidance leading to the parallel patterning of nerves and vessels in vivo. PMID:21828101

  2. Posterior ankle impingement syndrome.

    PubMed

    Maquirriain, Javier

    2005-10-01

    Posterior ankle impingement syndrome is a clinical disorder characterized by posterior ankle pain that occurs in forced plantar flexion. The pain may be acute as a result of trauma or chronic from repetitive stress. Pathology of the os trigonum-talar process is the most common cause of this syndrome, but it also may result from flexor hallucis longus tenosynovitis, ankle osteochondritis, subtalar joint disease, and fracture. Patients usually report chronic or recurrent posterior ankle pain caused or exacerbated by forced plantar flexion or push-off maneuvers, such as may occur during dancing, kicking, or downhill running. Diagnosis of posterior ankle impingement syndrome is based primarily on clinical history and physical examination. Radiography, scintigraphy, computed tomography, and magnetic resonance imaging depict associated bone and soft-tissue abnormalities. Symptoms typically improve with nonsurgical management, but surgery may be required in refractory cases. PMID:16224109

  3. Infrahyoid and accessory motoneurons in the Japanese monkey (Macaca fuscata).

    PubMed

    Ueyama, T; Satoda, T; Tashiro, T; Sugimoto, T; Matsushima, R; Mizuno, N

    1990-01-15

    The segmental and topographical organization of motoneurons innervating the infrahyoid (IH) and the spinal accessory (AC) muscles was studied in the Japanese monkey (Macaca fuscata) with the retrograde horseradish peroxidase (HRP) method after application of HRP to the peripheral nerve branches supplying the IH and AC muscles. IH motoneurons constitute two distinct slender cell columns, a longer medial and a shorter lateral one. The medial cell column extends from the most caudal level of the hypoglossal nucleus to the lower levels of the second cervical (C2) cord segment. In the medial column, motoneurons supplying the sternohyoid and sternothyroid muscles are distributed at the medullary and C1 levels, while those innervating the omohyoid muscle are primarily distributed at the C2 level. The lateral cell column consists of motoneurons supplying the thyrohyoid muscle and extends from the most caudal level of the hypoglossal nucleus to the middle levels of the C1 cord segment. Axons of thyrohyoid motoneurons follow a dorsomedially directed bent emergent course, making a hairpin turn. AC motoneurons supplying the sternocleidomastoid (SC) and trapezius (TZ) muscles form a single slender cell column extending from the most rostral level of the pyramidal decussation to the middle levels of the C6 cord segment. SC motoneurons are distributed from the most rostral level of the pyramidal decussation to the middle levels of the C3 cord segment, while TZ motoneurons are distributed from the upper levels of the C2 cord segment to the lower levels of the C6 cord segment. At the levels of the C2 and C3 cord segments, both SC and TZ motoneurons are distributed in the AC cell column; the cluster of SC motoneurons is located dorsomedial to that of TZ motoneurons. PMID:2152765

  4. Gait mode recognition and control for a portable-powered ankle-foot orthosis.

    PubMed

    David Li, Yifan; Hsiao-Wecksler, Elizabeth T

    2013-06-01

    Ankle foot orthoses (AFOs) are widely used as assistive/rehabilitation devices to correct the gait of people with lower leg neuromuscular dysfunction and muscle weakness. We have developed a portable powered ankle-foot orthosis (PPAFO), which uses a pneumatic bi-directional rotary actuator powered by compressed CO2 to provide untethered dorsiflexor and plantarflexor assistance at the ankle joint. Since portability is a key to the success of the PPAFO as an assist device, it is critical to recognize and control for gait modes (i.e. level walking, stair ascent/descent). While manual mode switching is implemented in most powered orthotic/prosthetic device control algorithms, we propose an automatic gait mode recognition scheme by tracking the 3D position of the PPAFO from an inertial measurement unit (IMU). The control scheme was designed to match the torque profile of physiological gait data during different gait modes. Experimental results indicate that, with an optimized threshold, the controller was able to identify the position, orientation and gait mode in real time, and properly control the actuation. It was also illustrated that during stair descent, a mode-specific actuation control scheme could better restore gait kinematic and kinetic patterns, compared to using the level ground controller. PMID:24187192

  5. Assessment of the ankle muscle co-contraction during normal gait: a surface electromyography study.

    PubMed

    Di Nardo, Francesco; Mengarelli, Alessandro; Maranesi, Elvira; Burattini, Laura; Fioretti, Sandro

    2015-04-01

    The study was designed to assess the co-contractions of tibialis anterior (TA) and gastrocnemius lateralis (GL) in healthy young adults during gait at self-selected speed and cadence, in terms of variability of onset-offset muscular activation and occurrence frequency. Statistical gait analysis (SGA), a recent methodology performing a statistical characterization of gait by averaging spatio-temporal and EMG-based parameters over numerous strides, was performed in twenty-four healthy young adults. Co-contractions were assessed as the period of overlap between activation intervals of TA and GL. Results showed that GL and TA act as pure agonist/antagonists for ankle plantar/dorsiflexion (no co-contractions) in only 21.3 ± 8.2% of strides. In the remaining strides, statistically significant (p < 0.05) co-contractions appear in early stance (29.2 ± 1.7%), mid-stance (32.1 ± 18.3%) and swing (62.2 ± 2.0%). This significantly increased complexity in muscle recruitment strategy beyond the activation as pure ankle plantar/dorsiflexors, suggests that co-contractions are likely functional to further physiological tasks as foot inversion, balance improvement, control of ankle stability and knee flexion. This study represents the first attempt for the development in healthy young adults of a "normality" reference frame for GL/TA co-contractions, able to include the physiological variability of the phenomenon and eliminate the confounding effect of age. PMID:25465985

  6. Human ankle joint stiffness over the full range of muscle activation levels.

    PubMed

    Weiss, P L; Hunter, I W; Kearney, R E

    1988-01-01

    System identification techniques have been used to track changes in dynamic stiffness of the human ankle joint over a wide range of muscle contraction levels. Subjects lay supine on an experimental table with their left foot encased in a rigid, low-inertia cast which was fixed to an electro-hydraulic actuator operating as a position servo. Subjects generated tonic plantarflexor or dorsiflexor torques of different magnitudes ranging from rest to maximum voluntary contractions (MVC) during repeated presentations of a stochastic ankle angular position perturbation. Compliance impulse response functions (IRF) were determined from every 2.5 s perturbation sequence. The gain (G), natural frequency (omega n), and damping (zeta) parameters of the second-order model providing the best fit to each IRF were determined and used to compute the corresponding inertial (I), viscous (B) and elastic (K) stiffness parameters. The behaviour of these parameters with mean torque was found to follow two simple rules. First, the elastic parameter (K) increased in proportion to mean ankle torque as it was varied from rest to MVC; these changes were considerable involving increases of more than an order of magnitude. Second, the damping parameter (zeta) remained almost invariant over the entire range of contractions despite the dramatic changes in K. PMID:3410857

  7. Necdin Protects Embryonic Motoneurons from Programmed Cell Death

    PubMed Central

    Aebischer, Julianne; Sturny, Rachel; Andrieu, David; Rieusset, Anne; Schaller, Fabienne; Geib, Sandrine; Raoul, Cédric; Muscatelli, Françoise

    2011-01-01

    NECDIN belongs to the type II Melanoma Associated Antigen Gene Expression gene family and is located in the Prader-Willi Syndrome (PWS) critical region. Necdin-deficient mice develop symptoms of PWS, including a sensory and motor deficit. However, the mechanisms underlying the motor deficit remain elusive. Here, we show that the genetic ablation of Necdin, whose expression is restricted to post-mitotic neurons in the spinal cord during development, leads to a loss of 31% of specified motoneurons. The increased neuronal loss occurs during the period of naturally-occurring cell death and is not confined to specific pools of motoneurons. To better understand the role of Necdin during the period of programmed cell death of motoneurons we used embryonic spinal cord explants and primary motoneuron cultures from Necdin-deficient mice. Interestingly, while Necdin-deficient motoneurons present the same survival response to neurotrophic factors, we demonstrate that deletion of Necdin leads to an increased susceptibility of motoneurons to neurotrophic factor deprivation. We show that by neutralizing TNFα this increased susceptibility of Necdin-deficient motoneurons to trophic factor deprivation can be reduced to the normal level. We propose that Necdin is implicated through the TNF-receptor 1 pathway in the developmental death of motoneurons. PMID:21912643

  8. Testing the evolutionary conservation of vocal motoneurons in vertebrates.

    PubMed

    Albersheim-Carter, Jacob; Blubaum, Aleksandar; Ballagh, Irene H; Missaghi, Kianoush; Siuda, Edward R; McMurray, George; Bass, Andrew H; Dubuc, Réjean; Kelley, Darcy B; Schmidt, Marc F; Wilson, Richard J A; Gray, Paul A

    2016-04-01

    Medullary motoneurons drive vocalization in many vertebrate lineages including fish, amphibians, birds, and mammals. The developmental history of vocal motoneuron populations in each of these lineages remains largely unknown. The highly conserved transcription factor Paired-like Homeobox 2b (Phox2b) is presumed to be expressed in all vertebrate hindbrain branchial motoneurons, including laryngeal motoneurons essential for vocalization in humans. We used immunohistochemistry and in situ hybridization to examine Phox2b protein and mRNA expression in caudal hindbrain and rostral spinal cord motoneuron populations in seven species across five chordate classes. Phox2b was present in motoneurons dedicated to sound production in mice and frogs (bullfrog, African clawed frog), but not those in bird (zebra finch) or bony fish (midshipman, channel catfish). Overall, the pattern of caudal medullary motoneuron Phox2b expression was conserved across vertebrates and similar to expression in sea lamprey. These observations suggest that motoneurons dedicated to sound production in vertebrates are not derived from a single developmentally or evolutionarily conserved progenitor pool. PMID:26160673

  9. Simulated recruitment of medial rectus motoneurons by abducens internuclear neurons: synaptic specificity vs. intrinsic motoneuron properties.

    PubMed

    Dean, P

    1997-09-01

    Ocular motoneuron firing rate is linearly related to conjugate eye position with slope K above recruitment threshold theta. Within the population of ocular motoneurons K increases as theta increases. These differences in firing rate between motoneurons might be determined either by the intrinsic properties of the motoneurons, or by differences in synaptic input to them, or by a combination of the two. This question was investigated by simulating the input signal to medial rectus motoneurons (MR-MNs) from internuclear neurons of the abducens nucleus (INNs). INNs were represented as input nodes in a two-layer neural net, each with weighted connections to every output node representing an MR-MN. Individual simulated MR-MNs were assigned parameters corresponding to an intrinsic current threshold I(R) and an intrinsic frequency-current (f-I) slope gamma. Their firing rates were calculated from these parameters, together with the effective synaptic current produced by their synaptically weighted INN inputs, with the use of assumptions employed in computer simulations of spinal motoneuron pools. The experimentally observed firing rates of MR-MNs served as training data for the net. The following two training conditions were used: 1) synaptic weights were fixed and the intrinsic parameters of the MR-MNs were allowed to vary, corresponding to the situation in which each MR-MN receives a common synaptic drive and 2) intrinsic MR-MN properties were fixed and synaptic weights were allowed to vary. In each case, the varying quantities were trained with a form of gradient descent error reduction. The simulations revealed the following three problems with the common-drive model: 1) the recruitment of INNs produced nonlinear responses in MR-MNs with low thetas; 2) the range of I(R)s required to reproduce the observed range of theta were generally larger than those measured experimentally for cat ocular motoneurons; and 3) the intrinsic f-I slope gamma increased with I

  10. Voltage-dependent amplification of synaptic inputs in respiratory motoneurones.

    PubMed

    Enríquez Denton, M; Wienecke, J; Zhang, M; Hultborn, H; Kirkwood, P A

    2012-07-01

    The role of persistent inward currents (PICs) in cat respiratory motoneurones (phrenic inspiratory and thoracic expiratory) was investigated by studying the voltage-dependent amplification of central respiratory drive potentials (CRDPs), recorded intracellularly, with action potentials blocked with the local anaesthetic derivative, QX-314. Decerebrate unanaesthetized or barbiturate-anaesthetized preparations were used. In expiratory motoneurones, plateau potentials were observed in the decerebrates, but not under anaesthesia. For phrenic motoneurones, no plateau potentials were observed in either state (except in one motoneurone after the abolition of the respiratory drive by means of a medullary lesion), but all motoneurones showed voltage-dependent amplification of the CRDPs, over a wide range of membrane potentials, too wide to result mainly from PIC activation. The measurements of the amplification were restricted to the phase of excitation, thus excluding the inhibitory phase. Amplification was found to be greatest for the smallest CRDPs in the lowest resistance motoneurones and was reduced or abolished following intracellular injection of the NMDA channel blocker, MK-801. Plateau potentials were readily evoked in non-phrenic cervical motoneurones in the same (decerebrate) preparations. We conclude that the voltage-dependent amplification of synaptic excitation in phrenic motoneurones is mainly the result of NMDA channel modulation rather than the activation of Ca2+ channel mediated PICs, despite phrenic motoneurones being strongly immunohistochemically labelled for CaV1.3 channels. The differential PIC activation in different motoneurones, all of which are CaV1.3 positive, leads us to postulate that the descending modulation of PICs is more selective than has hitherto been believed. PMID:22495582

  11. Effect of passive stretching and jogging on the series elastic muscle stiffness and range of motion of the ankle joint

    PubMed Central

    McNair, Peter J; Stanley, Stephen N

    1996-01-01

    Objective To determine the effect of stretching and jogging on the series elastic muscle stiffness of the plantar flexors and on the range of dorsiflexion at the ankle joint. Methods 24 healthy subjects participated in this study. Each subject undertook all of the following protocols, in random order: (1) stretching protocol: five 30 s static stretches with 30 s rest between stretches; (2) aerobic jogging protocol: subjects ran on a treadmill for 10 min at 60% of their maximum age predicted heart rate; (3) combined protocol: subjects ran first and then stretched. A damped oscillation technique was used to measure the series elastic stiffness of the plantar flexors. Dorsiflexion of the ankle was assessed with a weights and pulley system that moved the ankle joint from a neutral position into dorsiflexion passively. Electromyography was used to monitor the activity of the plantar and dorsiflexors during these procedures. The statistical analysis of these data involved an analysis of covariance Results For decreasing series elastic muscle stiffness running was more effective than stretching (P<0.05). In contrast, the results for range of motion showed that the combination protocol and the stretching only protocol were more effective than the running only protocol (P < 0.05) for increasing dorsiflexion range of motion at the ankle. Conclusions Both jogging and static stretching exercises appear to be beneficial to individuals participating in sporting activities. ImagesFigure 2Figure 3Figure 4Figure 5Figure 6 PMID:9015593

  12. Ankle fracture - aftercare

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000548.htm Ankle fracture - aftercare To use the sharing features on this ... Sit with your foot elevated higher than your knee at least 4 times a day Apply an ...

  13. Ankle injuries in basketball players.

    PubMed

    Leanderson, J; Nemeth, G; Eriksson, E

    1993-01-01

    We carried out a retrospective study of the frequency of ankle sprains in basketball players. A questionnaire about previous ankle injuries, time off after such injuries, current ankle problems, personal data, number of practice hours and the use of prophylactic measures was sent out to 102 basketball players in a second division league in Sweden. Ninety-six players answered. 92% of them had suffered an ankle sprain while playing basketball, and of these 83% reported repeated sprains of one ankle. In the last two seasons, 78% of the players had injured at least one ankle. The injury frequency in the investigation was 5.5 ankle injuries per 1000 activity hours. 22% of the players used some kind of prophylactic support of their ankle joints. Because of the great number of ankle sprains and the disability in terms of time away from sports that they cause, prevention of these injuries is essential. PMID:8536029

  14. Electrotonic characteristics of alpha motoneurones of varying size

    PubMed Central

    Burke, R. E.; ten Bruggencate, G.

    1971-01-01

    1. The neuronal membrane responses to long constant current pulses (essentially current steps) have been studied in cat triceps surae motoneurones identified as to the type of muscle fibres, fast twitch (type F) or slow twitch (type S), innervated by the cell being studied. For each motoneurone the membrane time constant, τM, and input resistance, RN, were determined from the response to a current step. In addition, shorter time constants (`equalizing time constants') resulting from current spread into the dendrites were estimated by graphical analysis. 2. The electrotonic length of the combined motoneurone soma and dendritic tree was estimated from the current step data using the neuronal equivalent cylinder model formulated by Rall (Rall, 1969). The mean electrotonic length of the motoneurone equivalent cylinder was approximately 1·5 in both type F and type S motoneurones. The mean membrane time constant of type F cells was 5·6 msec and that of type S motoneurones was 6·7 msec. This difference in mean τM values was of border line statistical significance. 3. The results indicate that the electrotonic length of the combined dendritic trees of both large type F and small type S motoneurones is essentially the same. The implication of this conclusion for interpretation of previous analyses of the monosynaptic EPSP is discussed. PMID:5545177

  15. Extracellular Mutant SOD1 Induces Microglial-Mediated Motoneuron Injury

    PubMed Central

    Zhao, Weihua; Beers, David R.; Henkel, Jenny S.; Zhang, Wei; Urushitani, Makoto; Julien, Jean-Pierre; Appel, Stanley H.

    2009-01-01

    Through undefined mechanisms, dominant mutations in (Cu/Zn) superoxide dismutase-1 (mSOD1) cause the non-cell-autonomous death of motoneurons in inherited amyotrophic lateral sclerosis (ALS). Microgliosis at sites of motoneuron injury is a neuropathological hallmark of ALS. Extracellular mSOD1 causes motoneuron injury and triggers microgliosis in spinal cord cultures, but it is unclear whether the injury results from extracellular mSOD1 directly interacting with motoneurons or is mediated through mSOD1-activated microglia. To dissociate these potential mSOD1-mediated neurotoxic mechanisms, the effects of extracellular human mSOD1G93A or mSOD1G85R were assayed using primary cultures of motoneurons and microglia. The data demonstrate that exogenous mSOD1G93A did not cause detectable direct killing of motoneurons. In contrast, mSOD1G93A or mSOD1G85R did induce the morphological and functional activation of microglia, increasing their release of pro-inflammatory cytokines and free radicals. Furthermore, only when microglia were co-cultured with motoneurons did extracellular mSOD1G93A injure motoneurons. The microglial activation mediated by mSOD1G93A was attenuated using toll-like receptors (TLR) 2, TLR4 and CD14 blocking antibodies, or when microglia lacked CD14 expression. These data suggest that extracellular mSOD1G93A is not directly toxic to motoneurons but requires microglial activation for toxicity, utilizing CD14 and TLR pathways. This link between mSOD1 and innate immunity may offer novel therapeutic targets in ALS. PMID:19672969

  16. Doctor, I sprained my ankle.

    PubMed

    How, Choon How; Tan, Ken Jin

    2014-10-01

    Ankle sprains constitute the majority of ankle injuries, and result in pain, limited mobility/exercise and loss of school/work days. Ankle sprains involve at least one of the ankle ligaments and range from a micro tear to complete tear of the ligament or group of ligaments. The most common mechanism of ankle sprains is inversion stress of a plantar-flexed foot, while the most frequently injured ligament is the anterior talofibular ligament. The attending clinician needs to stratify the risk of fracture through history-taking and physical examination, manage the pain, assess long‑term complications and provide certification for rest and recovery. The Ottawa ankle rules may be useful. Graduated exercises to maintain the ankle's range of motion should be started early, after the resolution of initial pain and swelling. The risk of recurrent ankle injuries is often a combination of both mechanical and functional disabilities. PMID:25631892

  17. How to Tape an Ankle

    MedlinePlus

    ... Decide If You Need to See an Orthopaedic Foot and Ankle Specialist How to Care for a Sprained Ankle How to Be Non-weightbearing After Surgery Footwear All Site Content AOFAS / FootCareMD / How To... / Foot Injury / How to Tape an Ankle How to ...

  18. Neural control of phrenic motoneuron discharge

    PubMed Central

    Lee, Kun-Ze; Fuller, David D.

    2011-01-01

    Phrenic motoneurons (PMNs) provide a synaptic relay between bulbospinal respiratory pathways and the diaphragm muscle. PMNs also receive propriospinal inputs, although the functional role of these interneuronal projections has not been established. Here we review the literature regarding PMN discharge patterns during breathing and the potential mechanisms that underlie PMN recruitment. Anatomical and neurophysiological studies indicate that PMNs form a heterogeneous pool, with respiratory-related PMN discharge and recruitment patterns likely determined by a balance between intrinsic MN properties and extrinsic synaptic inputs. We also review the limited literature regarding PMN bursting during respiratory plasticity. Differential recruitment or rate modulation of PMN subtypes may underlie phrenic motor plasticity following neural injury and/or respiratory stimulation; however this possibility remains relatively unexplored. PMID:21376841

  19. Arthroscopic ankle arthrodesis.

    PubMed

    Elmlund, Anna O; Winson, Ian G

    2015-03-01

    Arthroscopic ankle arthrodesis is a good option for the treatment of end-stage ankle arthritis. The surgical technique involving the use of a standard 4.5-mm arthroscope is described. Standard anteromedial and anterolateral portals are used. Joint surfaces except the lateral gutter are prepared to point bleeding with motorized burr, abraider, and curettes. Rigid fixation is achieved with cannulated screws. The postoperative regime includes 12 weeks protection, staged from non-weight bearing through partial to full weight bearing. Advantages compared with the open procedure include shorter hospital stay and shorter time to union with similar or better union rates. PMID:25726484

  20. Ankle Arthroscopic Reconstruction of Lateral Ligaments (Ankle Anti-ROLL)

    PubMed Central

    Takao, Masato; Glazebrook, Mark; Stone, James; Guillo, Stéphane

    2015-01-01

    Ankle instability is a condition that often requires surgery to stabilize the ankle joint that will improve pain and function if nonoperative treatments fail. Ankle stabilization surgery may be performed as a repair in which the native existing anterior talofibular ligament or calcaneofibular ligament (or both) is imbricated or reattached. Alternatively, when native ankle ligaments are insufficient for repair, a reconstruction of the ligaments may be performed in which an autologous or allograft tendon is used to reconstruct the anterior talofibular ligament or calcaneofibular ligament (or both). Currently, ankle stabilization surgery is most commonly performed through an open incision, but arthroscopic ankle stabilization using repair techniques has been described and is being used more often. We present our technique for anatomic ankle arthroscopic reconstruction of the lateral ligaments (anti-ROLL) performed in an all–inside-out manner that is likely safe for patients and minimally invasive. PMID:26900560

  1. Aging of motoneurons and synaptic processes in the cat.

    PubMed

    Chase, M H; Morales, F R; Boxer, P A; Fung, S J

    1985-11-01

    The aging of spinal cord alpha motoneurons was explored in old cats with intracellular recording techniques to determine the basic membrane properties of these neurons and their monosynaptic response following activation of group Ia afferent fibers. The conduction velocity of the motoneurons' axons decreased in old animals (14 to 15 years of age) compared with adult controls (1 to 3 years of age). The input resistance of the motoneurons increased in the old cats; no change occurred in the resting membrane potential or spike amplitude. There was a reduction in the delay between the initial segment and the somadendritic components of the antidromic spike. The half-width duration of the monosynaptic EPSP in the old cats increased, but its amplitude did not change. These data indicate that a host of different membrane properties of spinal cord motoneurons and their Ia-monosynaptic input are affected by the aging process. Analysis of the results suggests that the degradation of neuronal processes occurs in all motoneurons rather than preferentially affecting a specific population of motoneurons. PMID:2996926

  2. Characteristics and organization of discharge properties in rat hindlimb motoneurons.

    PubMed

    Turkin, Vladimir V; O'Neill, Derek; Jung, Ranu; Iarkov, Alexandre; Hamm, Thomas M

    2010-09-01

    The discharge properties of hindlimb motoneurons in ketamine-xylazine anesthetized rats were measured to assess contributions of persistent intrinsic currents to these characteristics and to determine their distribution in motoneuron pools. Most motoneurons (30/37) responded to ramp current injections with adapting patterns of discharge and the frequency-current (f-I) relations of nearly all motoneurons included a steep subprimary range of discharge. Despite the prevalence of adapting f-I relations, responses included indications that persistent inward currents (PICs) were activated, including increased membrane noise and prepotentials before discharge, as well as counterclockwise hysteresis and secondary ranges in f-I relations. Examination of spike thresholds and afterhyperpolarization (AHP) trajectories during repetitive discharge revealed systematic changes in threshold and trajectory within the subprimary, primary, and secondary f-I ranges. These changes in the primary and secondary ranges were qualitatively similar to those described previously for cat motoneurons. Within the subprimary range, AHP trajectories often included shallow approaches to threshold following recruitment and slope of the AHP ramp consistently increased until the subprimary range was reached. We suggest that PICs activated near recruitment contributed to these slope changes and formation of the subprimary range. Discharge characteristics were strongly correlated with motoneuron size, using input conductance as an indicator of size. Discharge adaptation, recruitment current, and frequency increased with input conductance, whereas both subprimary and primary f-I gains decreased. These results are discussed with respect to potential mechanisms and their functional implications. PMID:20592119

  3. SUCCESSFUL TRANSPLANTATION OF MOTONEURONS INTO THE PERIPHERAL NERVE DEPENDS ON THE NUMBER OF TRANSPLANTED CELLS

    PubMed Central

    KATO, SHUICHI; KURIMOTO, SHIGERU; NAKANO, TOMONORI; YONEDA, HIDEMASA; ISHII, HISAO; MITA-SUGIURA, SATOKA; HIRATA, HITOSHI

    2015-01-01

    ABSTRACT Transplantation of motoneurons (MN) into the peripheral nerve to provide a source of neurons for muscle reinnervation, termed motoneuron integrated striated muscle (MISM), may provide the potential to restore functional muscle activity, when combined with computer-programmed functional electrical stimulation (FES). The number of MNs required to restore innervation to denervated muscles in adult Fischer 344 rats was investigated by comparing two groups, one transplanted with 2 × 105 cells (group A) and the other with 1 × 106 cells (group B). Twelve weeks after transplantation, electrophysiological analysis, muscle function analysis, and tissue analysis were performed. The mean motor nerve conduction velocity was faster (12.4 ± 1.0 m/s vs. 8.5 ± 0.7 m/s, P = 0.011) and the mean amplitude of compound muscle action potential was larger (1.6 ± 0.4 mV vs. 0.7 ± 0.2 mV, P = 0.034) in group B. The dorsiflexed ankle angle was larger in group B (27 ± 5° vs. 75 ± 8°, P = 0.02). The mean myelinated axon number in the peroneal nerve and the proportion of reinnervated motor end plates were also greater in group B (317 ± 33 vs. 104 ± 17, 87.5 ± 3.4% vs. 40.6 ± 7.7%; P < 0.01, respectively). When sufficient MNs are transplanted into the peripheral nerve, MISM forms functional motor units. MISM, in conjunction with FES, provides a new treatment strategy for paralyzed muscles. PMID:25797991

  4. Doctor, I sprained my ankle

    PubMed Central

    How, Choon How; Tan, Ken Jin

    2014-01-01

    Ankle sprains constitute the majority of ankle injuries, and result in pain, limited mobility/exercise and loss of school/work days. Ankle sprains involve at least one of the ankle ligaments and range from a micro tear to complete tear of the ligament or group of ligaments. The most common mechanism of ankle sprains is inversion stress of a plantar-flexed foot, while the most frequently injured ligament is the anterior talofibular ligament. The attending clinician needs to stratify the risk of fracture through history-taking and physical examination, manage the pain, assess long-term complications and provide certification for rest and recovery. The Ottawa ankle rules may be useful. Graduated exercises to maintain the ankle’s range of motion should be started early, after the resolution of initial pain and swelling. The risk of recurrent ankle injuries is often a combination of both mechanical and functional disabilities. PMID:25631892

  5. [Tuberculosis of ankle].

    PubMed

    Rubio Barbón, S; Rodríguez Cocina, B; Suárez del Villar Acebal, R; Calvo Rodríguez, C E; Villar López, A; Escalada Rodríguez, P; Torreblanca Gil, A

    2004-09-01

    The authors present a case of tuberculous arthritis of ankle with sinovial fluid and sputum aspirate Lowenstein positive (M. tuberculosis) in a patient non inmunocomprometid and review the clinical, diagnosis and treatment aspects of this entity, and show the difficult diagnosis in cases of radiology normal or low suspect. PMID:15476422

  6. Ankle syndesmosis injuries.

    PubMed

    Peña, Fernando A; Coetzee, J Chris

    2006-03-01

    Physician awareness of ankle syndesmosis injuries is improving. The anatomy involved and the mechanism of injury are extremely relevant for the understanding and treatment of this type of injury. Examination under anesthesia may confirm the syndesmosis instability. Based on those findings, stabilization is the recommended approach. PMID:16564452

  7. Lectin-based Isolation and Culture of Mouse Embryonic Motoneurons

    PubMed Central

    Conrad, Rebecca; Jablonka, Sibylle; Sczepan, Teresa; Sendtner, Michael; Wiese, Stefan; Klausmeyer, Alice

    2011-01-01

    Spinal motoneurons develop towards postmitotic stages through early embryonic nervous system development and subsequently grow out dendrites and axons. Neuroepithelial cells of the neural tube that express Nkx6.1 are the unique precursor cells for spinal motoneurons1. Though postmitotic motoneurons move towards their final position and organize themselves into columns along the spinal tract2,3. More than 90% of all these differentiated and positioned motoneurons express the transcription factors Islet 1/2. They innervate the muscles of the limbs as well as those of the body and the inner organs. Among others, motoneurons typically express the high affinity receptors for brain derived neurotrophic factor (BDNF) and Neurotrophin-3 (NT-3), the tropomyosin-related kinase B and C (TrkB, TrkC). They do not express the tropomyosin-related kinase A (TrkA)4. Beside the two high affinity receptors, motoneurons do express the low affinity neurotrophin receptor p75NTR. The p75NTR can bind all neurotrophins with similar but lower affinity to all neurotrophins than the high affinity receptors would bind the mature neurotrophins. Within the embryonic spinal cord, the p75NTR is exclusively expressed by the spinal motoneurons5. This has been used to develop motoneuron isolation techniques to purify the cells from the vast majority of surrounding cells6. Isolating motoneurons with the help of specific antibodies (panning) against the extracellular domains of p75NTR has turned out to be an expensive method as the amount of antibody used for a single experiment is high due to the size of the plate used for panning. A much more economical alternative is the use of lectin. Lectin has been shown to specifically bind to p75NTR as well7. The following method describes an alternative technique using wheat germ agglutinin for a preplating procedure instead of the p75NTR antibody. The lectin is an extremely inexpensive alternative to the p75NTR antibody and the purification grades using

  8. Developing electrical properties of postnatal mouse lumbar motoneurons

    PubMed Central

    Durand, Jacques; Filipchuk, Anton; Pambo-Pambo, Arnaud; Amendola, Julien; Borisovna Kulagina, Iryna; Guéritaud, Jean-Patrick

    2015-01-01

    We studied the rapid changes in electrical properties of lumbar motoneurons between postnatal days 3 and 9 just before mice weight-bear and walk. The input conductance and rheobase significantly increased up to P8. A negative correlation exists between the input resistance (Rin) and rheobase. Both parameters are significantly correlated with the total dendritic surface area of motoneurons, the largest motoneurons having the lowest Rin and the highest rheobase. We classified the motoneurons into three groups according to their discharge firing patterns during current pulse injection (transient, delayed onset, sustained). The delayed onset firing type has the highest rheobase and the fastest action potential (AP) whereas the transient firing group has the lowest rheobase and the less mature AP. We found 32 and 10% of motoneurons with a transient firing at P3–P5 and P8, respectively. About 20% of motoneurons with delayed onset firing were detected at P8. At P9, all motoneurons exhibit a sustained firing. We defined five groups of motoneurons according to their discharge firing patterns in response to ascending and descending current ramps. In addition to the four classical types, we defined a fifth type called transient for the quasi-absence of discharge during the descending phase of the ramp. This transient type represents about 40% between P3–P5 and tends to disappear with age. Types 1 and 2 (linear and clockwise hysteresis) are the most preponderant at P6–P7. Types 3 and 4 (prolonged sustained and counter clockwise hysteresis) emerge at P8–P9. The emergence of types 3 and 4 probably depends on the maturation of L type calcium channels in the dendrites of motoneurons. No correlation was found between groups defined by step or triangular ramp of currents with the exception of transient firing patterns. Our data support the idea that a switch in the electrical properties of lumbar motoneurons might exist in the second postnatal week of life in mice. PMID

  9. Behaviour of the motoneurone pool in a fatiguing submaximal contraction

    PubMed Central

    McNeil, Chris J; Giesebrecht, Sabine; Gandevia, Simon C; Taylor, Janet L

    2011-01-01

    Abstract During fatigue caused by a sustained maximal voluntary contraction (MVC), motoneurones become markedly less responsive when tested during the silent period following transcranial magnetic stimulation (TMS). To determine whether this reduction depends on the repetitive activation of the motoneurones, responses to TMS (motor evoked potentials, MEPs) and to cervicomedullary stimulation (cervicomedullary motor evoked potentials, CMEPs) were tested during a sustained submaximal contraction at a constant level of electromyographic activity (EMG). In such a contraction, some motoneurones are repetitively activated whereas others are not active. On four visits, eight subjects performed a 10 min maintained-EMG elbow flexor contraction of 25% maximum. Test stimuli were delivered with and without conditioning by TMS given 100 ms prior. Test responses were MEPs or CMEPs (two visits each, small responses evoked by weak stimuli on one visit and large responses on the other). During the sustained contraction, unconditioned CMEPs decreased ∼20% whereas conditioned CMEPs decreased ∼75 and 30% with weak and strong stimuli, respectively. Conditioned MEPs were reduced to the same extent as CMEPs of the same size. The data reveal a novel decrease in motoneurone excitability during a submaximal contraction if EMG is maintained. Further, the much greater reduction of conditioned than unconditioned CMEPs shows the critical influence of voluntary drive on motoneurone responsiveness. Strong test stimuli attenuate the reduction of conditioned CMEPs which indicates that low-threshold motoneurones active in the contraction are most affected. The equivalent reduction of conditioned MEPs and CMEPs suggests that, similar to findings with a sustained MVC, impaired motoneurone responsiveness rather than intracortical inhibition is responsible for the fatigue-related impairment of the MEP during a sustained submaximal contraction. PMID:21606110

  10. Behaviour of the motoneurone pool in a fatiguing submaximal contraction.

    PubMed

    McNeil, Chris J; Giesebrecht, Sabine; Gandevia, Simon C; Taylor, Janet L

    2011-07-15

    During fatigue caused by a sustained maximal voluntary contraction (MVC), motoneurones become markedly less responsive when tested during the silent period following transcranial magnetic stimulation (TMS). To determine whether this reduction depends on the repetitive activation of the motoneurones, responses to TMS (motor evoked potentials, MEPs) and to cervicomedullary stimulation (cervicomedullary motor evoked potentials, CMEPs) were tested during a sustained submaximal contraction at a constant level of electromyographic activity (EMG). In such a contraction, some motoneurones are repetitively activated whereas others are not active. On four visits, eight subjects performed a 10 min maintained-EMG elbow flexor contraction of 25% maximum. Test stimuli were delivered with and without conditioning by TMS given 100 ms prior. Test responses were MEPs or CMEPs (two visits each, small responses evoked by weak stimuli on one visit and large responses on the other). During the sustained contraction, unconditioned CMEPs decreased ∼20% whereas conditioned CMEPs decreased ∼75 and 30% with weak and strong stimuli, respectively. Conditioned MEPs were reduced to the same extent as CMEPs of the same size. The data reveal a novel decrease in motoneurone excitability during a submaximal contraction if EMG is maintained. Further, the much greater reduction of conditioned than unconditioned CMEPs shows the critical influence of voluntary drive on motoneurone responsiveness. Strong test stimuli attenuate the reduction of conditioned CMEPs which indicates that low-threshold motoneurones active in the contraction are most affected. The equivalent reduction of conditioned MEPs and CMEPs suggests that, similar to findings with a sustained MVC, impaired motoneurone responsiveness rather than intracortical inhibition is responsible for the fatigue-related impairment of the MEP during a sustained submaximal contraction. PMID:21606110

  11. Cat hindlimb motoneurons during locomotion. III. Functional segregation in sartorius.

    PubMed

    Hoffer, J A; Loeb, G E; Sugano, N; Marks, W B; O'Donovan, M J; Pratt, C A

    1987-02-01

    Cat sartorius has two distinct anatomical portions, anterior (SA-a) and medial (SA-m). SA-a acts to extend the knee and also to flex the hip. SA-m acts to flex both the knee and the hip. The objective of this study was to investigate how a "single motoneuron pool" is used to control at least three separate functions mediated by the two anatomical portions of one muscle. Discharge patterns of single motoneurons projecting to the sartorius muscle were recorded using floating microelectrodes implanted in the L5 ventral root of cats. The electromyographic activity generated by the anterior and medial portions of sartorius was recorded with chronically implanted electrodes. The muscle portion innervated by each motoneuron was determined by spike-triggered averaging of the EMGs during walking on a motorized treadmill. During normal locomotion, SA-a exhibited two bursts of EMG activity per step cycle, one during the stance phase and one during the late swing phase. In contrast, every recorded motoneuron projecting to SA-a discharged a single burst of action potentials per step cycle. Some SA-a motoneurons discharged only during the stance phase, whereas other motoneurons discharged only during the late swing phase. In all cases, the instantaneous frequencygram of the motoneuron was well fit by the rectified smoothed EMG envelope generated by SA-a during the appropriate phase of the step cycle. During normal locomotion, SA-m exhibited a single burst of EMG activity per step cycle, during the swing phase. The temporal characteristics of the EMG bursts recorded from SA-m differed from the swing-phase EMG bursts generated by SA-a.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3559692

  12. Reflexes in cat ankle muscles after landing from falls.

    PubMed Central

    Prochazka, A; Schofield, P; Westerman, R A; Ziccone, S P

    1977-01-01

    1. Electrical activity and length of ankle muscles were recorded by telemetry during free fall and landing in cats. 2. After foot contact, there was a delay in onset of stretch of ankle extensors of between 8 and 11 ms. High-speed cinematography showed the delay to be associated with rapid initial dorsiflexion of the toes. 3. Electromyograms (e.m.g.) from lateral gastrocnemius increased in amplitude prior to landing. An early depression of lateral gastrocnemius e.m.g. commenced at 8 ms after foot contact, and was followed by a large peak of activity commencing some 8 ms after the first increase in lateral gastrocnemius length. 4. Local anaesthesia of the plantar cushion did not alter this pattern of response. 5. The early inhibition of lateral gastrocnemius was attributed to the action on lateral gastrocnemius motoneurones of non-cutaneous afferents responding to the initial toe dorsiflexion. Additional autogenetic inhibition may also have contributed. 6. The subsequent peak of e.m.g. was at a latenty consistent with a rapid stretch reflex, and occurred soon enough for the resulting active tension to contribute significantly to the extensor force during body deceleration. PMID:592210

  13. Intrinsic excitability differs between murine hypoglossal and spinal motoneurons.

    PubMed

    Tadros, M A; Fuglevand, A J; Brichta, A M; Callister, R J

    2016-05-01

    Motoneurons differ in the behaviors they control and their vulnerability to disease and aging. For example, brain stem motoneurons such as hypoglossal motoneurons (HMs) are involved in licking, suckling, swallowing, respiration, and vocalization. In contrast, spinal motoneurons (SMs) innervating the limbs are involved in postural and locomotor tasks requiring higher loads and lower movement velocities. Surprisingly, the properties of these two motoneuron pools have not been directly compared, even though studies on HMs predominate in the literature compared with SMs, especially for adult animals. Here we used whole cell patch-clamp recording to compare the electrophysiological properties of HMs and SMs in age-matched neonatal mice (P7-P10). Passive membrane properties were remarkably similar in HMs and SMs, and afterhyperpolarization properties did not differ markedly between the two populations. HMs had narrower action potentials (APs) and a faster upstroke on their APs compared with SMs. Furthermore, HMs discharged APs at higher frequencies in response to both step and ramp current injection than SMs. Therefore, while HMs and SMs have similar passive properties, they differ in their response to similar levels of depolarizing current. This suggests that each population possesses differing suites of ion channels that allow them to discharge at rates matched to the different mechanical properties of the muscle fibers that drive their distinct motor functions. PMID:26936988

  14. A medullary inhibitory region for trigeminal motoneurons in the cat.

    PubMed

    Castillo, P; Pedroarena, C; Chase, M H; Morales, F R

    1991-05-24

    The present report describes the effects on trigeminal motoneurons of stimulation of a circumscribed site within the parvocellular region of the medullary reticular formation. This medullary site was selected because anatomical studies have shown that premotor interneurons project from this site to the trigeminal motorpool. Electrical stimulation of this site induced IPSPs (PcRF-IPSPs) in jaw-closer motoneurons. A population of these IPSPs, recorded contralateral to the site of stimulation, exhibited latencies shorter than 1.5 ms (mean 1.16 +/- 0.08 SD). Their mean amplitude was 1.72 mV +/- 1.13 SD and their mean duration was 3.52 ms +/- 2.15 SD. We believe that these PcRF-IPSPs arose as the result of activation of a monosynaptic pathway. A comparable inhibitory input from this site to ipsilateral jaw-closer motoneurons and to both contra and ipsilateral digastric motoneurons was also observed. We therefore conclude that this medullary PcRF site contains premotor interneurons that are capable of postsynaptically inhibiting motoneurons that innervate antagonistic jaw muscles. PMID:1884229

  15. [Ankle braces prevent ligament injuries].

    PubMed

    Karlsson, Jon

    2002-09-01

    The Cochrane collaboration has performed a meta-analysis of all studies found on the prevention of ankle ligament injuries, frequent in sports like soccer, European handball and basketball. Interventions include the use of modified footwear and associated supports, training programmes and health education. Five randomized trials totalling 3,954 participants were included. With the exception of ankle disc training, all prophylactic interventions entailed the application of an external ankle support in the form of a semi-rigid orthosis, air-cast or high top shoes. The studies showed a significant reduction in the number of ankle sprains in individuals allocated to external ankle support. This reduction was greater for those with a previous history of ankle sprains. PMID:12362747

  16. Update on acute ankle sprains.

    PubMed

    Tiemstra, Jeffrey D

    2012-06-15

    Ankle sprains are a common problem seen by primary care physicians, especially among teenagers and young adults. Most ankle sprains are inversion injuries to the lateral ankle ligaments, although high sprains representing damage to the tibiofibular syndesmosis are becoming increasingly recognized. Physicians should apply the Ottawa ankle rules to determine whether radiography is needed. According to the Ottawa criteria, radiography is indicated if there is pain in the malleolar or midfoot zone, and either bone tenderness over an area of potential fracture (i.e., lateral malleolus, medial malleolus, base of fifth metatarsal, or navicular bone) or an inability to bear weight for four steps immediately after the injury and in the emergency department or physician's office. Patients with ankle sprain should use cryotherapy for the first three to seven days to reduce pain and improve recovery time. Patients should wear a lace-up ankle support or an air stirrup brace combined with an elastic compression wrap to reduce swelling and pain, speed recovery, and protect the injured ligaments as they become more mobile. Early mobilization speeds healing and reduces pain more effectively than prolonged rest. Pain control options for patients with ankle sprain include nonsteroidal anti-inflammatory drugs, acetaminophen, and mild opioids. Because a previous ankle sprain is the greatest risk factor for an acute ankle sprain, recovering patients should be counseled on prevention strategies. Ankle braces and supports, ankle taping, a focused neuromuscular training program, and regular sport-specific warm-up exercises can protect against ankle injuries, and should be considered for patients returning to sports or other high-risk activities. PMID:22962897

  17. What Is a Foot and Ankle Surgeon?

    MedlinePlus

    ... Text Size Print Bookmark What is a Foot & Ankle Surgeon? Foot and ankle surgeons are the surgical specialists of the podiatric ... every age. What education has a foot and ankle surgeon received? After completing undergraduate education, the foot ...

  18. Acute ankle sprain: an update.

    PubMed

    Ivins, Douglas

    2006-11-15

    Acute ankle injury, a common musculoskeletal injury, can cause ankle sprains. Some evidence suggests that previous injuries or limited joint flexibility may contribute to ankle sprains. The initial assessment of an acute ankle injury should include questions about the timing and mechanism of the injury. The Ottawa Ankle and Foot Rules provide clinical guidelines for excluding a fracture in adults and children and determining if radiography is indicated at the time of injury. Reexamination three to five days after injury, when pain and swelling have improved, may help with the diagnosis. Therapy for ankle sprains focuses on controlling pain and swelling. PRICE (Protection, Rest, Ice, Compression, and Elevation) is a well-established protocol for the treatment of ankle injury. There is some evidence that applying ice and using nonsteroidal antiinflammatory drugs improves healing and speeds recovery. Functional rehabilitation (e.g., motion restoration and strengthening exercises) is preferred over immobilization. Superiority of surgical repair versus functional rehabilitation for severe lateral ligament rupture is controversial. Treatment using semirigid supports is superior to using elastic bandages. Support devices provide some protection against future ankle sprains, particularly in persons with a history of recurrent sprains. Ankle disk or proprioceptive neuromuscular facilitation exercise regimens also may be helpful, although the literature supporting this is limited. PMID:17137000

  19. The distribution of motoneurones supplying chick hind limb muscles.

    PubMed Central

    Landmesser, L

    1978-01-01

    1. The motor nuclei supplying many of the hind limb muscles were localized in late chick embryos (stage 36-37; 10-11 days) by utilizing the technique of retrograde transport of horseradish peroxidase. 2. Each nucleus was found to be localized in a characteristic position in both the rostro-caudal and transverse plane of the spinal cord with only slight individual variation. 3. Each motor nucleus consisted of an elongate, coherent cluster of labelled cells, with few cells occurring outside the cluster. Thus, there did not appear to be extensive overlap of nuclei nor extensive intermingling of motoneurones projecting to different muscles. 4. The position of a motor nucleus in the transverse plane was not correlated with whether its muscle was used as an extensor or flexor; nor were adjacent nuclei necessarily co-activated during normal unrestrained walking movements as deduced from e.m.g. recordings. The position of a motor nucleus also was not correlated in a topographical manner with the adult position in the limb of the muscle to which it projected. 5. Further, while no correlation was found between the rostrocaudal position of a motor nucleus and the embryonic muscle mass from which its muscle was derived, such a relationship existed for the medio-lateral position; all muscles arising from the dorsal muscle mass, regardless of their function or adult position, were innervated by laterally situated motoneurones, all muscles arising from the ventral muscle mass by medially situated motoneurones. 6. It is concluded that motoneurone position is most closely correlated with ontogenetic events presumaeriphery. It can also be inferred that the central connexions onto motoneurones, responsible for their proper activation, cannot be achieved by a simple mechanism based largely on the position of the motoneurone soma. Images Text-fig. 6 Plate 1 PMID:731549

  20. Side-Alternating Vibration Training for Balance and Ankle Muscle Strength in Untrained Women

    PubMed Central

    Spiliopoulou, Styliani I.; Amiridis, Ioannis G.; Tsigganos, Georgios; Hatzitaki, Vassilia

    2013-01-01

    Context: Side-alternating vibration (SAV) may help reduce the risk of falling by improving body balance control. Such training has been promoted as a strength-training intervention because it can increase muscle activation through an augmented excitatory input from the muscle spindles. Objective: To determine the effect of SAV training on static balance during 3 postural tasks of increasing difficulty and lower limb strength. Design: Randomized controlled clinical trial. Setting: Laboratory. Patients or Other Participants: A total of 21 healthy women were divided into training (n = 11; age = 43.35 ± 4.12 years, height = 169 ± 6.60 cm, mass = 68.33 ± 11.90 kg) and control (n = 10; age = 42.31 ± 3.73 years, height = 167 ± 4.32 cm, mass = 66.29 ± 10.74 kg) groups. Intervention(s): The training group completed a 9-week program during which participants performed 3 sessions per week of ten 15-second isometric contractions with a 30-second active rest of 3 exercises (half-squat, wide-stance squat, 1-legged half-squat) on an SAV plate (acceleration = 0.91–16.3g). The control group did not participate in any form of exercise over the 9-week period. Main Outcome Measure(s): We evaluated isokinetic and isometric strength of the knee extensors and flexors and ankle plantar flexors, dorsiflexors, and evertors. Static balance was assessed using 3 tasks of increasing difficulty (quiet bipedal stance, tandem stance, 1-legged stance). The electromyographic activity of the vastus lateralis, semitendinosus, medial gastrocnemius, tibialis anterior, and peroneus longus was recorded during postural task performance, baseline and pretraining, immediately posttraining, and 15 days posttraining. Results: After training in the training group, ankle muscle strength improved (P = .03), whereas knee muscle strength remained unaltered (P = .13). Improved ankle-evertor strength was observed at all angular velocities (P = .001). Postural sway decreased in both directions but was greater

  1. Effects of a training program after surgically treated ankle fracture: a prospective randomised controlled trial

    PubMed Central

    Nilsson, Gertrud M; Jonsson, Kjell; Ekdahl, Charlotte S; Eneroth, Magnus

    2009-01-01

    Background Despite conflicting results after surgically treated ankle fractures few studies have evaluated the effects of different types of training programs performed after plaster removal. The aim of this study was to evaluate the effects of a 12-week standardised but individually suited training program (training group) versus usual care (control group) after plaster removal in adults with surgically treated ankle fractures. Methods In total, 110 men and women, 18-64 years of age, with surgically treated ankle fracture were included and randomised to either a 12-week training program or to a control group. Six and twelve months after the injury the subjects were examined by the same physiotherapist who was blinded to the treatment group. The main outcome measure was the Olerud-Molander Ankle Score (OMAS) which rates symptoms and subjectively scored function. Secondary outcome measures were: quality of life (SF-36), timed walking tests, ankle mobility tests, muscle strength tests and radiological status. Results 52 patients were randomised to the training group and 58 to the control group. Five patients dropped out before the six-month follow-up resulting in 50 patients in the training group and 55 in the control group. Nine patients dropped out between the six- and twelve-month follow-up resulting in 48 patients in both groups. When analysing the results in a mixed model analysis on repeated measures including interaction between age-group and treatment effect the training group demonstrated significantly improved results compared to the control group in subjects younger than 40 years of age regarding OMAS (p = 0.028), muscle strength in the plantar flexors (p = 0.029) and dorsiflexors (p = 0.030). Conclusion The results of this study suggest that when adjusting for interaction between age-group and treatment effect the training model employed in this study was superior to usual care in patients under the age of 40. However, as only three out of nine outcome

  2. Hypoxic response of hypoglossal motoneurones in the in vivo cat.

    PubMed Central

    Pierrefiche, O; Bischoff, A M; Richter, D W; Spyer, K M

    1997-01-01

    1. In current and voltage clamp, the effects of hypoxia were studied on resting and synaptic properties of hypoglossal motoneurones in barbiturate-anaesthetized adult cats. 2. Twenty-nine hypoglossal motoneurones with a mean membrane potential of -55 mV responded rapidly to acute hypoxia with a persistent membrane depolarization of about +17 mV. This depolarization correlated with the development of a persistent inward current of 0.3 nA at holding potentials close to resting membrane potential. 3. Superior laryngeal nerve (SLN) stimulation-evoked EPSPs were reduced in amplitude by, on average, 46% while IPSP amplitude was reduced by 31% SLN stimulation-evoked EPSCs were reduced by 50-70%. 4. Extracellular application of adenosine (10 mM) hyperpolarized hypoglossal motoneurones by, on average, 5.6 mV, from a control value of -62 mV. SLN stimulation-evoked EPSPs decreased by 18% and IPSPs decreased by 46% during adenosine application. 5. Extracellular application of the KATP channel blocker glibenclamide led to a blockade of a persistent outward current and a significant increase of SLN stimulation-evoked EPSCs. 6. We conclude that hypoglossal motoneurones have a very low tolerance to hypoxia. They appear to be under metabolic stress even in normoxia and their capacity to activate protective potassium currents is limited when compared with other brainstem neurones. This may help to explain the rapid disturbance of hypoglossal function during energy depletion. PMID:9457652

  3. Modulation of human motoneuron activity by a mental arithmetic task.

    PubMed

    Bensoussan, Laurent; Duclos, Yann; Rossi-Durand, Christiane

    2012-10-01

    This study aimed to determine whether the performance of a mental task affects motoneuron activity. To this end, the tonic discharge pattern of wrist extensor motor units was analyzed in healthy subjects while they were required to maintain a steady wrist extension force and to concurrently perform a mental arithmetic (MA) task. A shortening of the mean inter-spike interval (ISI) and a decrease in ISI variability occurred when MA task was superimposed to the motor task. Aloud and silent MA affected equally the rate and variability of motoneuron discharge. Increases in surface EMG activity and force level were consistent with the modulation of the motor unit discharge rate. Trial-by-trial analysis of the characteristics of motor unit firing revealed that performing MA increases activation of wrist extensor SMU. It is suggested that increase in muscle spindle afferent activity, resulting from fusimotor drive activation by MA, may have contributed to the increase in synaptic inputs to motoneurons during the mental task performance, likely together with enhancement in the descending drive. The finding that a mental task affects motoneuron activity could have consequences in assessment of motor disabilities and in rehabilitation in motor pathologies. PMID:23159444

  4. Can Chronic Ankle Instability be Prevented? Rethinking Management of Lateral Ankle Sprains.

    ERIC Educational Resources Information Center

    Denegar, Craig R.; Miller, Sayers J., III

    2002-01-01

    Investigates whether chronic ankle instability can be prevented, discussing: the relationship between mechanical and functional instability; normal ankle mechanics, sequelae to lateral ankle sprains, and abnormal ankle mechanics; and tissue healing, joint dysfunction, and acute lateral ankle sprain management. The paper describes a treatment model…

  5. Central pupillary light reflex circuits in the cat: II. Morphology, ultrastructure, and inputs of preganglionic motoneurons.

    PubMed

    Sun, Wensi; May, Paul J

    2014-12-15

    Preganglionic motoneurons supplying the ciliary ganglion control lens accommodation and pupil diameter. In cats, these motoneurons make up the preganglionic Edinger-Westphal population, which lies rostral, dorsal, and ventral to the oculomotor nucleus. A recent cat study suggested that caudal motoneurons control the lens and rostral motoneurons control the pupil. This led us to examine the morphology, ultrastructure, and pretectal inputs of these populations. Preganglionic motoneurons retrogradely labeled by introducing tracer into the cat ciliary ganglion generally fell into two morphologic categories. Fusiform neurons were located rostrally, in the anteromedian nucleus and between the oculomotor nuclei. Multipolar neurons were found caudally, dorsal and ventral to the oculomotor nucleus. The dendrites of preganglionic motoneurons within the anteromedian nucleus crossed the midline, providing a possible basis for consensual responses. Ultrastructurally, several different classes of synaptic profiles contact preganglionic motoneurons, suggesting that their activity may be modified by a variety of inputs. Furthermore, there were differences in the synaptic populations contacting the rostral vs. caudal populations, supporting the contention that these populations display functional differences. Anterogradely labeled pretectal terminals were observed in close association with labeled preganglionic motoneurons, particularly in the rostral population. Ultrastructural analysis revealed that these terminals, packed with clear, spherical vesicles, made asymmetric synaptic contacts onto motoneurons in the rostral population, indicating that these cells serve the pupillary light reflex. Thus, the preganglionic motoneurons found in the cat display morphologic, ultrastructural, and connectional differences suggesting that this rostral preganglionic population is specialized for pupil control, whereas more caudal elements control the lens. PMID:24706263

  6. Early intrinsic hyperexcitability does not contribute to motoneuron degeneration in amyotrophic lateral sclerosis

    PubMed Central

    Leroy, Félix; Lamotte d'Incamps, Boris; Imhoff-Manuel, Rebecca D; Zytnicki, Daniel

    2014-01-01

    In amyotrophic lateral sclerosis (ALS) the large motoneurons that innervate the fast-contracting muscle fibers (F-type motoneurons) are vulnerable and degenerate in adulthood. In contrast, the small motoneurons that innervate the slow-contracting fibers (S-type motoneurons) are resistant and do not degenerate. Intrinsic hyperexcitability of F-type motoneurons during early postnatal development has long been hypothesized to contribute to neural degeneration in the adult. Here, we performed a critical test of this hypothesis by recording from identified F- and S-type motoneurons in the superoxide dismutase-1 mutant G93A (mSOD1), a mouse model of ALS at a neonatal age when early pathophysiological changes are observed. Contrary to the standard hypothesis, excitability of F-type motoneurons was unchanged in the mutant mice. Surprisingly, the S-type motoneurons of mSDO1 mice did display intrinsic hyperexcitability (lower rheobase, hyperpolarized spiking threshold). As S-type motoneurons are resistant in ALS, we conclude that early intrinsic hyperexcitability does not contribute to motoneuron degeneration. DOI: http://dx.doi.org/10.7554/eLife.04046.001 PMID:25313866

  7. A repertoire of rhythmic bursting produced by hypoglossal motoneurons in physiological and pathological conditions

    PubMed Central

    Cifra, Alessandra; Nani, Francesca; Sharifullina, Elina; Nistri, Andrea

    2009-01-01

    The brainstem nucleus hypoglossus contains motoneurons that provide the exclusive motor nerve supply to the tongue. In addition to voluntary tongue movements, tongue muscles rhythmically contract during a wide range of physiological activities, such as respiration, swallowing, chewing and sucking. Hypoglossal motoneurons are destroyed early in amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease often associated with a deficit in the transport system of the neurotransmitter glutamate. The present study shows how periodic electrical discharges of motoneurons are mainly produced by a neuronal network that drives them into bursting mode via glutamatergic excitatory synapses. Burst activity is, however, modulated by the intrinsic properties of motoneurons that collectively synchronize their discharges via gap junctions to create ‘group bursters’. When glial uptake of glutamate is blocked, a distinct form of pathological bursting spontaneously emerges and leads to motoneuron death. Conversely, H2O2-induced oxidative stress strongly increases motoneuron excitability without eliciting bursting. Riluzole (the only drug currently licensed for the treatment of ALS) suppresses bursting of hypoglossal motoneurons caused by blockage of glutamate uptake and limits motoneuron death. These findings highlight how different patterns of electrical oscillations of brainstem motoneurons underpin not only certain physiological activities, but also motoneuron death induced by glutamate transporter impairment. PMID:19651651

  8. Central Pupillary Light Reflex Circuits in the Cat: II. Morphology, Ultrastructure and Inputs of Preganglionic Motoneurons

    PubMed Central

    Sun, Wensi; May, Paul J.

    2014-01-01

    Preganglionic motoneurons supplying the ciliary ganglion control lens accommodation and pupil diameter. In cats, these motoneurons make up the preganglionic Edinger-Westphal population, which lies rostral, dorsal and ventral to the oculomotor nucleus. A recent cat study suggested that caudal motoneurons control the lens and rostral motoneurons control the pupil. This led us to examine the morphology, ultrastructure and pretectal inputs of these populations. Preganglionic motoneurons retrogradely labeled by introducing tracer into the cat ciliary ganglion generally fell into two morphologic categories. Fusiform neurons were located rostrally, in the anteromedian nucleus and between the oculomotor nuclei. Multipolar neurons were found caudally, dorsal and ventral to the oculomotor nucleus. The dendrites of preganglionic motoneurons within the anteromedian nucleus crossed the midline, providing a possible basis for consensual responses. Ultrastructurally, several different classes of synaptic profiles contact preganglionic motoneurons, suggesting their activity may be modified by a variety of inputs. Furthermore, there were differences between the synaptic populations contacting the rostral and caudal populations, supporting the contention that these populations display functional differences. Anterogradely labeled pretectal terminals were observed in close association with labeled preganglionic motoneurons, particularly in the rostral population. Ultrastructural analysis revealed that these terminals, packed with clear, spherical vesicles, made asymmetric synaptic contacts onto motoneurons in the rostral population indicating these cells serve the pupillary light reflex. Thus, the preganglionic motoneurons found in the cat display morphologic, ultrastructural and connectional differences suggesting that this rostral preganglionic population is specialized for pupil control, while more caudal elements control the lens. PMID:24706263

  9. Early intrinsic hyperexcitability does not contribute to motoneuron degeneration in amyotrophic lateral sclerosis

    PubMed Central

    Leroy, Félix; Lamotte d'Incamps, Boris; Imhoff-Manuel, Rebecca D; Zytnicki, Daniel

    2014-01-01

    In amyotrophic lateral sclerosis (ALS) the large motoneurons that innervate the fast-contracting muscle fibers (F-type motoneurons) are vulnerable and degenerate in adulthood. In contrast, the small motoneurons that innervate the slow-contracting fibers (S-type motoneurons) are resistant and do not degenerate. Intrinsic hyperexcitability of F-type motoneurons during early postnatal development has long been hypothesized to contribute to neural degeneration in the adult. Here, we performed a critical test of this hypothesis by recording from identified F- and S-type motoneurons in the superoxide dismutase-1 mutant G93A (mSOD1), a mouse model of ALS at a neonatal age when early pathophysiological changes are observed. Contrary to the standard hypothesis, excitability of F-type motoneurons was unchanged in the mutant mice. Surprisingly, the S-type motoneurons of mSDO1 mice did display intrinsic hyperexcitability (lower rheobase, hyperpolarized spiking threshold). As S-type motoneurons are resistant in ALS, we conclude that early intrinsic hyperexcitability does not contribute to motoneuron degeneration. DOI: http://dx.doi.org/10.7554/eLife.04046.001

  10. Succinate dehydrogenase activity and soma size of motoneurons innervating different portions of the rat tibialis anterior

    NASA Technical Reports Server (NTRS)

    Ishihara, A.; Roy, R. R.; Edgerton, V. R.

    1995-01-01

    The spatial distribution, soma size and oxidative enzyme activity of gamma and alpha motoneurons innervating muscle fibres in the deep (away from the surface of the muscle) and superficial (close to the surface of the muscle) portions of the tibialis anterior in normal rats were determined. The deep portion had a higher percentage of high oxidative fibres than the superficial portion of the muscle. Motoneurons were labelled by retrograde neuronal transport of fluorescent tracers: Fast Blue and Nuclear Yellow were injected into the deep portion and Nuclear Yellow into the superficial portion of the muscle. Therefore, motoneurons innervating the deep portion were identified by both a blue fluorescent cytoplasm and a golden-yellow fluorescent nucleus, while motoneurons innervating the superficial portion were identified by only a golden-yellow fluorescent nucleus. After staining for succinate dehydrogenase activity on the same section used for the identification of the motoneurons, soma size and succinate dehydrogenase activity of the motoneurons were measured. The gamma and alpha motoneurons innervating both the deep and superficial portions were located primarily at L4 and were intermingled within the same region of the dorsolateral portion of the ventral horn in the spinal cord. Mean soma size was similar for either gamma or alpha motoneurons in the two portions of the muscle. The alpha motoneurons innervating the superficial portion had a lower mean succinate dehydrogenase activity than those innervating the deep portion of the muscle. An inverse relationship between soma size and succinate dehydrogenase activity of alpha, but not gamma, motoneurons innervating both the deep and superficial portions was observed. Based on three-dimensional reconstructions within the spinal cord, there were no apparent differences in the spatial distribution of the motoneurons, either gamma or alpha, associated with the deep and superficial compartments of the muscle. The data

  11. Arthroscopic Repair of Ankle Instability.

    PubMed

    Sorensen, Matthew D; Baca, John; Arbuckle, Keith

    2016-10-01

    Arthroscopic lateral ankle stabilization procedures have been described for many years. New technological advances and a deeper understanding of the pathobiomechanics involved in chronic lateral ankle instability have allowed an expansion of arthroscopic approaches to this common pathology. As experience is gained and outcomes within the patient profile are understood, the authors feel that the arthroscopic approach to lateral ankle stabilization may prove superior to traditional methods secondary to the risk and traditional complications that are mitigated within minimally invasive arthroscopic approaches. Additionally, the arthroscopic approach may allow a quicker return to ballistic sport and decrease time for rehabilitation. PMID:27599440

  12. Clinical application of a robotic ankle training program for cerebral palsy compared to the research laboratory application: Does it translate to practice?

    PubMed Central

    Sukal-Moulton, Theresa; Clancy, Theresa; Zhang, Li-Qun; Gaebler-Spira, Deborah

    2014-01-01

    Objective To determine the clinical efficacy of an ankle robotic rehabilitation protocol for patients with cerebral palsy. Design The clinic cohort was identified from a retrospective chart review in a before-after intervention trial design and compared to a previously published prospective research cohort. Setting Urban rehabilitation hospital outpatient clinic. Participants Children (n=28, 8.2 ± 3.62 years) with Gross Motor Function Classification System level I, II or III who were referred for ankle stretching and strengthening used an ankle rehabilitation robot in the clinic setting. Clinic results were compared to a previously published cohort of 12 participants (7.8 ± 2.91 years) seen in a research laboratory-based intervention protocol. Interventions Patients in the clinic cohort were seen 2 times per week for 75 minute sessions for a total of 6 weeks. The first 30 minutes of the session was spent using the robotic ankle device for ankle stretching and strengthening and the remaining 45 minutes were spent on functional movement activities. There was no control group. Main Outcome Measures We compared pre- and post-intervention measures of plantarflexor and dorsiflexor range of motion, strength, spasticity, mobility (timed up and go, 6-minute walk, 10-meter walk), balance (Pediatric Balance Scale), Selective Motor Control Assessment of the Lower Extremity (SCALE), and the Gross Motor Function Measure (GMFM). Results Significant improvements were found for the clinic cohort in all main outcome measures except for the GMFM. These improvements were equivalent to those reported in the research cohort, except for larger SCALE test changes in the research cohort. Conclusion These findings suggest that translation of repetitive, goal directed biofeedback training into the clinic setting is both feasible and beneficial for patients with cerebral palsy. PMID:24792141

  13. Ankle Fractures Often Not Diagnosed

    MedlinePlus

    ... side of the ankle. This condition often... Barefoot Running Barefoot running is running while barefoot, without wearing any shoes on the feet. Running in thin-soled, flexible shoes is related but ...

  14. [Arthroscopic surgery of the ankle].

    PubMed

    Bojanić, Ivan; Franić, Miljenko; Ivković, Alan

    2007-05-01

    Arthroscopic surgery of the ankle has become indispensable method in the armamentarium of the modern orthopaedic surgeon. Technological advancement and thorough understanding of the anatomy have resulted in improved ability to perform arthroscopy of the ankle. The method is minimally invasive and it allows the direct visualization of intra-articular structures without arthrotomy or malleolar osteotomy. Anterior or posterior approach may be used, and various indications have become generally accepted: anterior soft tissue or bony impingement, loose bodies, osteochondral defects, synovitis (rheumatoid arthritis, infective arthritis, and hemophilic arthropathy), posterior impingement syndrome, posttraumatic conditions, osteoarthritis (arthrosis), ankle arthrodesis, tumor-like lesions (synovial osteochondromatosis, pigmented villonodular synovitis) and many combinations of these pathological entities. In this paper we will discuss technique, indications, complications and future perspective of the ankle arthroscopy. In addition we will review the most recent literature data regarding this appealing technique. PMID:17695197

  15. Foot, leg, and ankle swelling

    MedlinePlus

    ... feet - legs; Ankle swelling; Foot swelling; Leg swelling; Edema - peripheral; Peripheral edema ... 51. Trayes KP, Studdiford JS, Pickle S, Tully AS. Edema: Diagnosis and management. Am Fam Phys . 2013;88( ...

  16. Effects of ankle balance taping with kinesiology tape for a patient with chronic ankle instability.

    PubMed

    Kim, Byeong-Jo; Lee, Jung-Hoon; Kim, Chang-Tae; Lee, Sun-Min

    2015-07-01

    [Purpose] To report the effects of ankle balance taping for a patient with chronic ankle instability (CAI). [Subject] A 33-year-old man with a 10 year history of chronic ankle stability. [Methods] ABT with kinesiology tape was performed for 2 months (average, 16 h/day) around the right ankle. [Results] At the end of two months, no ankle instability was noted when ascending and descending the stairs, jumping, turning, operating the pedals while driving, and lifting heavy objects. [Conclusion] The repeated use of kinesiology tape in ankle balance taping may be an effective treatment for recovering the ankle stability of patients with chronic ankle instability. PMID:26311206

  17. Effects of ankle balance taping with kinesiology tape for a patient with chronic ankle instability

    PubMed Central

    Kim, Byeong-Jo; Lee, Jung-Hoon; Kim, Chang-Tae; Lee, Sun-Min

    2015-01-01

    [Purpose] To report the effects of ankle balance taping for a patient with chronic ankle instability (CAI). [Subject] A 33-year-old man with a 10 year history of chronic ankle stability. [Methods] ABT with kinesiology tape was performed for 2 months (average, 16 h/day) around the right ankle. [Results] At the end of two months, no ankle instability was noted when ascending and descending the stairs, jumping, turning, operating the pedals while driving, and lifting heavy objects. [Conclusion] The repeated use of kinesiology tape in ankle balance taping may be an effective treatment for recovering the ankle stability of patients with chronic ankle instability. PMID:26311206

  18. Mechanism and Design Analysis of Articulated Ankle Foot Orthoses for Drop-Foot

    PubMed Central

    Choudhury, Imtiaz Ahmed; Mamat, Azuddin Bin

    2014-01-01

    Robotic technologies are being employed increasingly in the treatment of lower limb disabilities. Individuals suffering from stroke and other neurological disorders often experience inadequate dorsiflexion during swing phase of the gait cycle due to dorsiflexor muscle weakness. This type of pathological gait, mostly known as drop-foot gait, has two major complications, foot-slap during loading response and toe-drag during swing. Ankle foot orthotic (AFO) devices are mostly prescribed to resolve these complications. Existing AFOs are designed with or without articulated joint with various motion control elements like springs, dampers, four-bar mechanism, series elastic actuator, and so forth. This paper examines various AFO designs for drop-foot, discusses the mechanism, and identifies limitations and remaining design challenges. Along with two commercially available AFOs some designs possess promising prospective to be used as daily-wear device. However, the design and mechanism of AFO must ensure compactness, light weight, low noise, and high efficiency. These entailments present significant engineering challenges to develop a new design with wide consumer adoption. PMID:24892102

  19. Human distal sciatic nerve fascicular anatomy: implications for ankle control using nerve-cuff electrodes.

    PubMed

    Gustafson, Kenneth J; Grinberg, Yanina; Joseph, Sheeba; Triolo, Ronald J

    2012-01-01

    The design of neural prostheses to restore standing balance, prevent foot drop, or provide active propulsion during ambulation requires detailed knowledge of the distal sciatic nerve anatomy. Three complete sciatic nerves and branches were dissected from the piriformis to each muscle entry point to characterize the branching patterns and diameters. Fascicle maps were created from serial sections of each distal terminus below the knee through the anastomosis of the tibial and common fibular nerves above the knee. Similar branching patterns and fascicle maps were observed across specimens. Fascicles innervating primary plantar flexors, dorsiflexors, invertors, and evertors were distinctly separate and functionally organized in the proximal tibial, common fibular, and distal sciatic nerves; however, fascicles from individual muscles were not apparent at these levels. The fascicular organization is conducive to selective stimulation for isolated and/or balanced dorsiflexion, plantar flexion, eversion, and inversion through a single multicontact nerve-cuff electrode. These neuroanatomical data are being used to design nerve-cuff electrodes for selective control of ankle movement and improve current lower-limb neural prostheses. PMID:22773531

  20. Transmitter inputs to different motoneuron subgroups in the oculomotor and trochlear nucleus in monkey.

    PubMed

    Zeeh, Christina; Mustari, Michael J; Hess, Bernhard J M; Horn, Anja K E

    2015-01-01

    In all vertebrates the eyes are moved by six pairs of extraocular muscles enabling horizontal, vertical and rotatory movements. Recent work showed that each extraocular muscle is controlled by two motoneuronal groups: (1) Motoneurons of singly-innervated muscle fibers (SIF) that lie within the boundaries of motonuclei mediating a fast muscle contraction; and (2) motoneurons of multiply-innervated muscle fibers (MIF) in the periphery of motonuclei mediating a tonic muscle contraction. Currently only limited data about the transmitter inputs to the SIF and MIF motoneurons are available. Here we performed a quantitative study on the transmitter inputs to SIF and MIF motoneurons of individual muscles in the oculomotor and trochlear nucleus in monkey. Pre-labeled motoneurons were immunostained for GABA, glutamate decarboxylase, GABA-A receptor, glycine transporter 2, glycine receptor 1, and vesicular glutamate transporters 1 and 2. The main findings were: (1) the inhibitory control of SIF motoneurons for horizontal and vertical eye movements differs. Unlike in previous primate studies a considerable GABAergic input was found to all SIF motoneuronal groups, whereas a glycinergic input was confined to motoneurons of the medial rectus (MR) muscle mediating horizontal eye movements and to those of the levator palpebrae (LP) muscle elevating the upper eyelid. Whereas SIF and MIF motoneurons of individual eye muscles do not differ numerically in their GABAergic, glycinergic and vGlut2 input, vGlut1 containing terminals densely covered the supraoculomotor area (SOA) targeting MR MIF motoneurons. It is reasonable to assume that the vGlut1 input affects the near response system in the SOA, which houses the preganglionic neurons mediating pupillary constriction and accommodation and the MR MIF motoneurones involved in vergence. PMID:26257611

  1. Inhibition of Sirt1 promotes neural progenitors toward motoneuron differentiation from human embryonic stem cells

    SciTech Connect

    Zhang, Yun; Wang, Jing; Chen, Guian; Fan, Dongsheng; Deng, Min

    2011-01-14

    Research highlights: {yields} Nicotinamide inhibit Sirt1. {yields} MASH1 and Ngn2 activation. {yields} Increase the expression of HB9. {yields} Motoneurons formation increases significantly. -- Abstract: Several protocols direct human embryonic stem cells (hESCs) toward differentiation into functional motoneurons, but the efficiency of motoneuron generation varies based on the human ESC line used. We aimed to develop a novel protocol to increase the formation of motoneurons from human ESCs. In this study, we tested a nuclear histone deacetylase protein, Sirt1, to promote neural precursor cell (NPC) development during differentiation of human ESCs into motoneurons. A specific inhibitor of Sirt1, nicotinamide, dramatically increased motoneuron formation. We found that about 60% of the cells from the total NPCs expressed HB9 and {beta}III-tubulin, commonly used motoneuronal markers found in neurons derived from ESCs following nicotinamide treatment. Motoneurons derived from ESC expressed choline acetyltransferase (ChAT), a positive marker of mature motoneuron. Moreover, we also examined the transcript levels of Mash1, Ngn2, and HB9 mRNA in the differentiated NPCs treated with the Sirt1 activator resveratrol (50 {mu}M) or inhibitor nicotinamide (100 {mu}M). The levels of Mash1, Ngn2, and HB9 mRNA were significantly increased after nicotinamide treatment compared with control groups, which used the traditional protocol. These results suggested that increasing Mash1 and Ngn2 levels by inhibiting Sirt1 could elevate HB9 expression, which promotes motoneuron differentiation. This study provides an alternative method for the production of transplantable motoneurons, a key requirement in the development of hESC-based cell therapy in motoneuron disease.

  2. Transmitter inputs to different motoneuron subgroups in the oculomotor and trochlear nucleus in monkey

    PubMed Central

    Zeeh, Christina; Mustari, Michael J.; Hess, Bernhard J. M.; Horn, Anja K. E.

    2015-01-01

    In all vertebrates the eyes are moved by six pairs of extraocular muscles enabling horizontal, vertical and rotatory movements. Recent work showed that each extraocular muscle is controlled by two motoneuronal groups: (1) Motoneurons of singly-innervated muscle fibers (SIF) that lie within the boundaries of motonuclei mediating a fast muscle contraction; and (2) motoneurons of multiply-innervated muscle fibers (MIF) in the periphery of motonuclei mediating a tonic muscle contraction. Currently only limited data about the transmitter inputs to the SIF and MIF motoneurons are available. Here we performed a quantitative study on the transmitter inputs to SIF and MIF motoneurons of individual muscles in the oculomotor and trochlear nucleus in monkey. Pre-labeled motoneurons were immunostained for GABA, glutamate decarboxylase, GABA-A receptor, glycine transporter 2, glycine receptor 1, and vesicular glutamate transporters 1 and 2. The main findings were: (1) the inhibitory control of SIF motoneurons for horizontal and vertical eye movements differs. Unlike in previous primate studies a considerable GABAergic input was found to all SIF motoneuronal groups, whereas a glycinergic input was confined to motoneurons of the medial rectus (MR) muscle mediating horizontal eye movements and to those of the levator palpebrae (LP) muscle elevating the upper eyelid. Whereas SIF and MIF motoneurons of individual eye muscles do not differ numerically in their GABAergic, glycinergic and vGlut2 input, vGlut1 containing terminals densely covered the supraoculomotor area (SOA) targeting MR MIF motoneurons. It is reasonable to assume that the vGlut1 input affects the near response system in the SOA, which houses the preganglionic neurons mediating pupillary constriction and accommodation and the MR MIF motoneurones involved in vergence. PMID:26257611

  3. Neuroprotective effects of testosterone on dendritic morphology following partial motoneuron depletion: Efficacy in female rats

    PubMed Central

    Wilson, Randall E.; Coons, Kellie D.; Sengelaub, Dale R.

    2009-01-01

    Motoneuron loss is a significant medical problem, capable of causing severe movement disorders and even death. We have previously demonstrated that partial depletion of motoneurons induces dendritic atrophy in remaining motoneurons, with a concomitant reduction in motor activation. Treatment of male rats with testosterone attenuates the regressive changes following partial motoneuron depletion. To test whether testosterone has similar effects in females, we examined potential neuroprotective effects in motoneurons innervating muscles of the quadriceps of female rats. Motoneurons were selectively killed by intramuscular injection of cholera toxin-conjugated saporin. Simultaneously, some saporin-injected rats were given implants containing testosterone or left untreated. Four weeks later, surviving motoneurons were labeled with cholera toxin-conjugated HRP, and dendritic arbors were reconstructed in 3 dimensions. Compared to normal females, partial motoneuron depletion resulted in decreased dendritic length in remaining quadriceps motoneurons, and this atrophy was greatly attenuated by testosterone treatment. These findings suggest that testosterone has neuroprotective effects on morphology in both males and females, further supporting a role for testosterone as a neurotherapeutic agent in the injured nervous system. PMID:19735695

  4. The control of sets of motoneurones by local interneurones in the locust.

    PubMed Central

    Burrows, M

    1980-01-01

    1. A motoneurone innervating a muscle in a hind leg of a locust is controlled in a graded manner by many non-spiking, local interneurones. There is overlap and fractionation of control between these interneurones. Some interneurones depolarize the motoneurone over part of its range, others hyperpolarize it, whilst some do both. 2. The interneurones organize the small number of motoneurones that innervate one muscle into overlapping sets of various sizes. A motoneurone can therefore be activated individually or in particular combinations with its fellow motoneurones. 3. The motoneurones innervating two muscles of a joint are also organized into overlapping sets by many local interneurones. This permits the motoneurones to the two muscles to be activated reciprocally, together, or independently. 4. One interneurone can elicit a co-ordinated movement of one, two or even three joints in a hind leg that are components of the normal behaviour of the locust. 5. A single interneurone acting alone does not usually elicit the maximum output from one motoneurone, nor a complete piece of behaviour. A stronger contraction of a muscle and a more complete movement results from the action of groups of interneurones. 6. It is suggested that local interneurones, exerting graded control over motoneurones are a major element in the organization of motor patterns in the locust. PMID:7359394

  5. State-dependent phenomena in cat masseter motoneurons.

    PubMed

    Kohlmeier, K A; López-Rodríguez, F; Liu, R H; Morales, F R; Chase, M H

    1996-05-25

    In the present study we explored the mechanisms of carbachol-induced muscle atonia in the alpha-chloralose-anesthetized animal. We compared our findings to those that have been previously obtained in unanesthetized cats during muscle atonia occurring during natural active sleep. Accordingly, in cats anesthetized with alpha-chloralose, intracellular records were obtained from masseter motoneurons before and after carbachol-induced motor atonia. Following the induction of atonia, the membrane potential activity was dominated by high-frequency, discrete, hyperpolarizing potentials. These hyperpolarizing potentials were reversed in polarity by the intracellular injection of chloride ions and abolished by the application of strychnine. These findings indicate that they were inhibitory postsynaptic potentials (IPSPs) mediated by glycine. These IPSPs appeared exclusively during muscle atonia. In addition, masseter motoneurons were significantly hyperpolarized and their rheobase increased. There was a decrease in input resistance and membrane time constant. In the alpha-chloralose-anesthetized preparation, stimulation of the nucleus pontis oralis (NPO) induced IPSPs in masseter motoneurons following, but never prior to, the pontine injection of carbachol. Thus, this is the first demonstration that "reticular response-reversal' may be elicited in an anesthetized preparation. Another state-dependent phenomenon of active sleep, the occurrence of IPSPs in motoneurons that are temporally correlated with ponto-geniculo-occipital (PGO) waves, was also observed in this preparation only after carbachol administration. Based on the data in this report, we conclude that the inhibitory system that mediates atonia during the state of active sleep can be activated in an animal that is anesthetized with alpha-chloralose. Specifically, the neuronal groups that generate spontaneous IPSPs, those that mediate the phenomenon of reticular response-reversal, and those involved in the generation

  6. Changes in the electrophysiological properties of cat spinal motoneurons following the intramuscular injection of adriamycin compared with changes in the properties of motoneurons in aged cats.

    PubMed

    Liu, R H; Yamuy, J; Xi, M C; Morales, F R; Chase, M H

    1995-11-01

    1. This study was undertaken to investigate the effects of adriamycin (ADM, Doxorubicin) on the basic electrophysiological properties of spinal cord motoneurons in the adult cat. ADM was injected into the biceps, gastrocnemius, semitendinosus, and semimembranosus muscles of the left hindlimb (1.2 mg per muscle). Intracellular recordings from motoneurons innervating these muscles were carried out 12, 20, or 40 days after ADM administration and from corresponding motoneurons in untreated control cats. 2. Twelve days after ADM injection, motoneurons innervating ADM-treated muscles (ADM MNs) exhibited statistically significant increases in input resistance, membrane time constant, and amplitude of the action potential's afterhyperpolarization (AHP). In addition, there was a statistically significant decrease in rheobase and in the delay between the action potential of the initial segment (IS) and that of the somadendritic (SD) portion of the motoneuron (IS-SD delay). There were no significant changes in the resting membrane potential, threshold depolarization, action potential amplitude, or axonal conduction velocity. 3. The changes in electrical properties of motoneurons at 20 and 40 days after ADM injection were qualitatively similar to those observed at 12 days. However, at 40 days after ADM injection there was a statistically significant decrease in the axonal conduction velocity of the ADM MNs. 4. The normal correlations that are present between the AHP duration and electrical properties of the control motoneurons were observed in the ADM MNs, e.g., AHP duration was positively correlated with the input resistance and time constant and negatively correlated with the axonal conduction velocity. The correlation coefficients, however, were reduced in comparison with the control data. 5. This study demonstrates that ADM exerts significant effects on the electrical properties of motoneurons when injected into their target muscles. The majority of the changes in

  7. The origin of the ankle

    NASA Astrophysics Data System (ADS)

    Codino, Antonio; Plouin, Francois

    2007-03-01

    The differential intensity of cosmic radiation shows a sequence of depressions referred to as knees in a large energy band above 1015eV. The global depression entailed in the complete spectrum with respect to the extrapolated intensity based on low energy data, amounts to a maximum factor of 8, occurring at 5×10eV, where flux measurements exhibit a relative minimum, referred to as the ankle. It is demonstrated by a full simulation of cosmic ray trajectories in the Galaxy that the intensity minimum around the ankle energy is primarily due to the nuclear interactions of the cosmic ions with the interstellar matter and to the galactic magnetic field. Ankles signal the onset energies of the rectilinear propagation in the Milky Way at Earth, being for example, 4×10eV for helium and 6×10eV for iron. The ankle, in spite of its notable importance at Earth, is a local perturbation of the universal spectrum which, between the knee and the ankle, decreases by a round factor 109 regaining its unperturbed status above 1019eV.

  8. Posterior Ankle Structure Injury During Total Ankle Replacement.

    PubMed

    Reb, Christopher W; McAlister, Jeffrey E; Hyer, Christopher F; Berlet, Gregory C

    2016-01-01

    Total ankle replacement studies have focused on reporting complications that are directly observed clinically or radiographically, including wound problems, technical errors, implant loosening, subsidence, infection, bone fractures, and heterotopic ossification. However, patients can still experience unresolved pain even when these problems have been ruled out. We initiated a study to more clearly define the relative risk of injury to the anatomic structures in the posterior ankle during total ankle replacement using a third-generation implant system. Ten fresh-frozen adult cadaveric below-the-knee specimens were positioned in the intraoperative positioning frame of an approved total ankle replacement system and adjusted to achieve proper foot alignment using fluoroscopic imaging. The relationship between the tibial cutting guide pins and the posterior neurovascular and tendon structures was measured using digital calipers. High rates of posterior structural injury were found. Nearly all proximal-medial pins encountered a posteromedial neurovascular structure, most commonly the tibial nerve. The distal-medial pins mainly encountered posteromedial tendinous structures, in particular, the flexor digitorum longus tendon. The proximal lateral pins were highly likely to encounter the Achilles tendon and the sural nerve. Our results support our hypothesis that the tibial neurovascular structures are at the greatest risk when preparing for and completing the bony resection, particularly with the medial and proximal cuts. Posterior ankle soft tissue structure injuries can occur during implantation but currently with unknown frequency and undetermined significance. Further study of posterior structural injuries could result in a more informed approach to post-total ankle replacement complications and management. PMID:27291681

  9. American Orthopaedic Foot and Ankle Society

    MedlinePlus

    ... education site of the American Orthopaedic Foot & Ankle Society. Patients Visit the official patient education site of the American Orthopaedic Foot & Ankle Society. Patients Visit the official patient education site of ...

  10. Osteoarthritis of the Foot and Ankle

    MedlinePlus

    ... Size Print Bookmark Osteoarthritis of the Foot and Ankle What Is Osteoarthritis? Osteoarthritis is a condition characterized ... is also often found in the midfoot and ankle. Causes Osteoarthritis is considered a “wear and tear” ...

  11. Effects of ankle eversion taping using kinesiology tape in a patient with ankle inversion sprain

    PubMed Central

    Lee, Sun-Min; Lee, Jung-Hoon

    2016-01-01

    [Purpose] The aim of this study was to report the effects of ankle eversion taping using kinesiology tape on ankle inversion sprain. [Subject] The subject was a 21-year-old woman with Grade 2 ankle inversion sprain. [Methods] Ankle eversion taping was applied to the sprained left ankle using kinesiology tape for 4 weeks (average, 15 h/day). [Results] Ankle instability and pain were reduced, and functional dynamic balance was improved after ankle eversion taping for 4 weeks. The Cumberland Ankle Instability Tool score and reach distances in the Y-Balance and lunge tests were increased. [Conclusion] Repeated ankle eversion taping may be an effective treatment intervention for ankle inversion sprain. PMID:27064668

  12. Effects of ankle eversion taping using kinesiology tape in a patient with ankle inversion sprain.

    PubMed

    Lee, Sun-Min; Lee, Jung-Hoon

    2016-01-01

    [Purpose] The aim of this study was to report the effects of ankle eversion taping using kinesiology tape on ankle inversion sprain. [Subject] The subject was a 21-year-old woman with Grade 2 ankle inversion sprain. [Methods] Ankle eversion taping was applied to the sprained left ankle using kinesiology tape for 4 weeks (average, 15 h/day). [Results] Ankle instability and pain were reduced, and functional dynamic balance was improved after ankle eversion taping for 4 weeks. The Cumberland Ankle Instability Tool score and reach distances in the Y-Balance and lunge tests were increased. [Conclusion] Repeated ankle eversion taping may be an effective treatment intervention for ankle inversion sprain. PMID:27064668

  13. Subperiosteal Hematoma of the Ankle

    PubMed Central

    Hui, S H; Lui, T H

    2016-01-01

    Introduction: Periosteal reaction has a long list of differential diagnoses ranging from trauma, infection, metabolic disease to malignancy. The morphology of periosteal reaction shown in imaging studies helps to narrow down the list of differential diagnoses. Case report: A 25 year old gentleman had an inversion injury to his left ankle. He complained of lateral ankle and posterior heel pain and swelling after the injury. Radiograph of his left ankle revealed solid, smooth periosteal reaction at posterior aspect of left distal tibia. MRI showed periosteal reaction at the corresponding site, which was better demonstrated in CT scan. Follow up MRI and CT showed maturation of the new bone formation at the site of periosteal reaction. Findings were compatible with subperiosteal hematoma formation from injury, which ossified with time. Conclusion: Smooth, thick periosteal reaction favours benign process, while interrupted pattern is an alarming feature for more aggressive causes. PMID:27299131

  14. The Incidence of Ankle Sprains in Orienteering.

    ERIC Educational Resources Information Center

    Ekstrand, Jan; And Others

    1990-01-01

    Investigates relationship between ankle sprains and participation time in competitive orienteering. Examined 15,474 competitors in races in the Swedish O-ringen 5-day event in 1987. Injuries requiring medical attention were analyzed, showing 137 (23.9 percent) ankle sprains. Injury incidence was 8.4/10,000 hours. Incidence of ankle sprains was…

  15. Sports Injuries to the Foot and Ankle

    MedlinePlus

    ... Print Bookmark Sports Injuries to the Foot and Ankle Depending on the sport, your feet and ankles can certainly take a beating from repetitive play. ... communities: Copyright © 2016 | American College of Foot and Ankle Surgeons (ACFAS), All Rights Reserved. | Privacy Statement | Disclaimer | ...

  16. Lateral ankle sprains and instability problems.

    PubMed

    Liu, S H; Jason, W J

    1994-10-01

    The lateral ankle complex is the most frequently injured single structure in athletes, consisting of 38% to 45% of all injuries. One-sixth of all sports injury loss time is from ankle sprains. In North America, ankle inversion sprains are considered "de rigeur" for basketball participation. PMID:7805107

  17. Early electrophysiological abnormalities in lumbar motoneurons in a transgenic mouse model of amyotrophic lateral sclerosis.

    PubMed

    Bories, Cyril; Amendola, Julien; Lamotte d'Incamps, Boris; Durand, Jacques

    2007-01-01

    Amyotrophic lateral sclerosis is a lethal, adult-onset disease characterized by progressive degeneration of motoneurons. Recent data have suggested that the disease could be linked to abnormal development of the motor nervous system. Therefore, we investigated the electrical properties of lumbar motoneurons in an in-vitro neonatal spinal cord preparation isolated from SOD1(G85R) mice, which is a transgenic model of amyotrophic lateral sclerosis. The study was performed on young animals at the beginning of their second week, between postnatal days 6 and 10. Measurements of resting membrane potential and action potential characteristics of motoneurons were similar in wild-type and SOD1(G85R) mice. However, the input resistance of motoneurons from transgenic mice was significantly lower than that of wild-type animals, whereas their membrane capacitance was increased, strongly suggesting larger SOD1(G85R) motoneurons. Furthermore, the slope of the frequency-intensity curve was steeper in motoneurons from wild-type pups. Interestingly, the input resistance as well as the slope of the frequency-intensity curves of other spinal neurons did not show such differences. Finally, the amplitude of dorsal root-evoked potentials following high-intensity stimulation was significantly smaller in SOD1(G85R) motoneurons. The superoxide dismutase 1 mutation thus induces specific alterations of the functional properties of motoneurons early in development. PMID:17284186

  18. Transcriptional enhancement of Smn levels in motoneurons is crucial for proper axon morphology in zebrafish

    PubMed Central

    Spiró, Zoltán; Koh, Angela; Tay, Shermaine; See, Kelvin; Winkler, Christoph

    2016-01-01

    An unresolved mystery in the field of spinal muscular atrophy (SMA) is why a reduction of the ubiquitously expressed Smn protein causes defects mostly in motoneurons. We addressed the possibility that this restricted vulnerability stems from elevated Smn expression in motoneurons. To explore this, we established an ex vivo zebrafish culture system of GFP-marked motoneurons to quantitatively measure Smn protein and smn mRNA levels as well as promoter activity in motoneurons versus other cell types. Importantly, we uncovered that Smn levels are elevated in motoneurons by means of transcriptional activation. In addition, we identified the ETS family transcription factor Etv5b to be responsible for increased smn transcription in motoneurons. Moreover, we established that the additional supply of Smn protein in motoneurons is necessary for proper axonogenesis in a cell-autonomous manner. These findings demonstrate the reliance of motoneurons on more Smn, thereby adding a novel piece of evidence for their increased vulnerability under SMA conditions. PMID:27273160

  19. Transcriptional enhancement of Smn levels in motoneurons is crucial for proper axon morphology in zebrafish.

    PubMed

    Spiró, Zoltán; Koh, Angela; Tay, Shermaine; See, Kelvin; Winkler, Christoph

    2016-01-01

    An unresolved mystery in the field of spinal muscular atrophy (SMA) is why a reduction of the ubiquitously expressed Smn protein causes defects mostly in motoneurons. We addressed the possibility that this restricted vulnerability stems from elevated Smn expression in motoneurons. To explore this, we established an ex vivo zebrafish culture system of GFP-marked motoneurons to quantitatively measure Smn protein and smn mRNA levels as well as promoter activity in motoneurons versus other cell types. Importantly, we uncovered that Smn levels are elevated in motoneurons by means of transcriptional activation. In addition, we identified the ETS family transcription factor Etv5b to be responsible for increased smn transcription in motoneurons. Moreover, we established that the additional supply of Smn protein in motoneurons is necessary for proper axonogenesis in a cell-autonomous manner. These findings demonstrate the reliance of motoneurons on more Smn, thereby adding a novel piece of evidence for their increased vulnerability under SMA conditions. PMID:27273160

  20. State-dependent control of lumbar motoneurons by the hypocretinergic system.

    PubMed

    Yamuy, Jack; Fung, Simon J; Xi, Mingchu; Chase, Michael H

    2010-02-01

    Neurons in the lateral hypothalamus (LH) that synthesize hypocretins (Hcrt-1 and Hcrt-2) are active during wakefulness and excite lumbar motoneurons. Because hypocretinergic cells also discharge during phasic periods of rapid eye movement (REM) sleep, we sought to examine their action on the activity of motoneurons during this state. Accordingly, cat lumbar motoneurons were intracellularly recorded, under alpha-chloralose anesthesia, prior to (control) and during the carbachol-induced REM sleep-like atonia (REMc). During control conditions, LH stimulation induced excitatory postsynaptic potentials (composite EPSP) in motoneurons. In contrast, during REMc, identical LH stimulation induced inhibitory PSPs in motoneurons. We then tested the effects of LH stimulation on motoneuron responses following the stimulation of the nucleus reticularis gigantocellularis (NRGc) which is part of a brainstem-spinal cord system that controls motoneuron excitability in a state-dependent manner. LH stimulation facilitated NRGc stimulation-induced composite EPSP during control conditions whereas it enhanced NRGc stimulation-induced IPSPs during REMc. These intriguing data indicate that the LH exerts a state-dependent control of motor activity. As a first step to understand these results, we examined whether hypocretinergic synaptic mechanisms in the spinal cord were state dependent. We found that the juxtacellular application of Hcrt-1 induced motoneuron excitation during control conditions whereas motoneuron inhibition was enhanced during REMc. These data indicate that the hypocretinergic system acts on motoneurons in a state-dependent manner via spinal synaptic mechanisms. Thus, deficits in Hcrt-1 may cause the coexistence of incongruous motor signs in cataplectic patients, such as motor suppression during wakefulness and movement disorders during REM sleep. PMID:19962375

  1. Opiate-Induced Suppression of Rat Hypoglossal Motoneuron Activity and Its Reversal by Ampakine Therapy

    PubMed Central

    Lorier, Amanda R.; Funk, Gregory D.; Greer, John J.

    2010-01-01

    Background Hypoglossal (XII) motoneurons innervate tongue muscles and are vital for maintaining upper-airway patency during inspiration. Depression of XII nerve activity by opioid analgesics is a significant clinical problem, but underlying mechanisms are poorly understood. Currently there are no suitable pharmacological approaches to counter opiate-induced suppression of XII nerve activity while maintaining analgesia. Ampakines accentuate α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) receptor responses. The AMPA family of glutamate receptors mediate excitatory transmission to XII motoneurons. Therefore the objectives were to determine whether the depressant actions of μ-opioid receptor activation on inspiratory activity includes a direct inhibitory action at the inspiratory premotoneuron to XII motoneuron synapse, and to identify underlying mechanism(s). We then examined whether ampakines counteract opioid-induced depression of XII motoneuron activity. Methodology/Principal Findings A medullary slice preparation from neonatal rat that produces inspiratory-related output in vitro was used. Measurements of inspiratory burst amplitude and frequency were made from XII nerve roots. Whole-cell patch recordings from XII motoneurons were used to measure membrane currents and synaptic events. Application of the μ-opioid receptor agonist, DAMGO, to the XII nucleus depressed the output of inspiratory XII motoneurons via presynaptic inhibition of excitatory glutamatergic transmission. Ampakines (CX614 and CX717) alleviated DAMGO-induced depression of XII MN activity through postsynaptic actions on XII motoneurons. Conclusions/Significance The inspiratory-depressant actions of opioid analgesics include presynaptic inhibition of XII motoneuron output. Ampakines counteract μ-opioid receptor-mediated depression of XII motoneuron inspiratory activity. These results suggest that ampakines may be beneficial in countering opiate-induced suppression of XII motoneuron

  2. Effects of background noise on the response of rat and cat motoneurones to excitatory current transients.

    PubMed Central

    Poliakov, A V; Powers, R K; Sawczuk, A; Binder, M D

    1996-01-01

    1. We studied the responses of rat hypoglossal motoneurones to excitatory current transients (ECTs) using a brainstem slice preparation. Steady, repetitive discharge at rates of 12-25 impulses s-1 was elicited from the motoneurones by injecting long (40 s) steps of constant current. Poisson trains of the ECTs were superimposed on these steps. The effects of additional synaptic noise was simulated by adding a zero-mean random process to the stimuli. 2. We measured the effects of the ECTs on motoneurone discharge probability by compiling peristimulus time histograms (PSTHs) between the times of occurrence of the ECTs and the motoneurone spikes. The ECTs produced modulation of motoneurone discharge similar to that produced by excitatory postsynaptic currents. 3. The addition of noise altered the pattern of the motoneurone response to the current transients: both the amplitude and the area of the PSTH peaks decreased as the power of the superimposed noise was increased. Noise tended to reduce the efficacy of the ECTs, particularly when the motoneurones were firing at lower frequencies. Although noise also increased the firing frequency of the motoneurones slightly, the effects of noise on ECT efficacy did not simply result from noise-induced changes in mean firing rate. 4. A modified version of the experimental protocol was performed in lumbar motoneurones of intact, pentobarbitone-anaesthetized cats. These recordings yielded results similar to those obtained in rat hypoglossal motoneurones in vitro. 5. Our results suggest that the presence of concurrent synaptic inputs reduces the efficacy of any one input. The implications of this change in efficacy and the possible underlying mechanisms are discussed. PMID:8866358

  3. Zebrafish Mnx proteins specify one motoneuron subtype and suppress acquisition of interneuron characteristics

    PubMed Central

    2012-01-01

    Background Precise matching between motoneuron subtypes and the muscles they innervate is a prerequisite for normal behavior. Motoneuron subtype identity is specified by the combination of transcription factors expressed by the cell during its differentiation. Here we investigate the roles of Mnx family transcription factors in specifying the subtypes of individually identified zebrafish primary motoneurons. Results Zebrafish has three Mnx family members. We show that each of them has a distinct and temporally dynamic expression pattern in each primary motoneuron subtype. We also show that two Mnx family members are expressed in identified VeLD interneurons derived from the same progenitor domain that generates primary motoneurons. Surprisingly, we found that Mnx proteins appear unnecessary for differentiation of VeLD interneurons or the CaP motoneuron subtype. Mnx proteins are, however, required for differentiation of the MiP motoneuron subtype. We previously showed that MiPs require two temporally-distinct phases of Islet1 expression for normal development. Here we show that in the absence of Mnx proteins, the later phase of Islet1 expression is initiated but not sustained, and MiPs become hybrids that co-express morphological and molecular features of motoneurons and V2a interneurons. Unexpectedly, these hybrid MiPs often extend CaP-like axons, and some MiPs appear to be entirely transformed to a CaP morphology. Conclusions Our results suggest that Mnx proteins promote MiP subtype identity by suppressing both interneuron development and CaP axon pathfinding. This is, to our knowledge, the first report of transcription factors that act to distinguish CaP and MiP subtype identities. Our results also suggest that MiP motoneurons are more similar to V2 interneurons than are CaP motoneurons. PMID:23122226

  4. Expecting ankle tilts and wearing an ankle brace influence joint control in an imitated ankle sprain mechanism during walking.

    PubMed

    Gehring, Dominic; Wissler, Sabrina; Lohrer, Heinz; Nauck, Tanja; Gollhofer, Albert

    2014-03-01

    A thorough understanding of the functional aspects of ankle joint control is essential to developing effective injury prevention. It is of special interest to understand how neuromuscular control mechanisms and mechanical constraints stabilize the ankle joint. Therefore, the aim of the present study was to determine how expecting ankle tilts and the application of an ankle brace influence ankle joint control when imitating the ankle sprain mechanism during walking. Ankle kinematics and muscle activity were assessed in 17 healthy men. During gait rapid perturbations were applied using a trapdoor (tilting with 24° inversion and 15° plantarflexion). The subjects either knew that a perturbation would definitely occur (expected tilts) or there was only the possibility that a perturbation would occur (potential tilts). Both conditions were conducted with and without a semi-rigid ankle brace. Expecting perturbations led to an increased ankle eversion at foot contact, which was mediated by an altered muscle preactivation pattern. Moreover, the maximal inversion angle (-7%) and velocity (-4%), as well as the reactive muscle response were significantly reduced when the perturbation was expected. While wearing an ankle brace did not influence muscle preactivation nor the ankle kinematics before ground contact, it significantly reduced the maximal ankle inversion angle (-14%) and velocity (-11%) as well as reactive neuromuscular responses. The present findings reveal that expecting ankle inversion modifies neuromuscular joint control prior to landing. Although such motor control strategies are weaker in their magnitude compared with braces, they seem to assist ankle joint stabilization in a close-to-injury situation. PMID:24365326

  5. Foot and ankle problems in dancers.

    PubMed

    Kadel, Nancy

    2014-11-01

    The dancer's foot and ankle are subjected to high forces and unusual stresses in training and performance. Injuries are common in dancers, and the foot and ankle are particularly vulnerable. Ankle sprains, ankle impingement syndromes, flexor hallucis longus tendonitis, cuboid subluxation, stress fractures, midfoot injuries, heel pain, and first metatarsophalangeal joint problems including hallux valgus, hallux rigidus, and sesamoid injuries will be reviewed. This article will discuss these common foot and ankle problems in dancers and give typical clinical presentation and diagnostic and treatment recommendations. PMID:25442161

  6. Distinguishing ankle and knee articular cartilage.

    PubMed

    Cole, Ada A; Margulis, Arkady; Kuettner, Klaus E

    2003-06-01

    Degenerative changes in the tall and femoral distal cartilages of more than 2,000 tissue donors were graded based on the appearance of articular cartilage and osteophytes. In the ankle and the knee the degenerative changes increased with age; however, the rate of degeneration in the ankle was slower than in the knee. The degenerative changes in the ankle were more severe in men than in women, were predominantly bilateral, and seemed to be correlated with weight. The slower rate of change in the ankle may be caused, in part, by the biochemical and biomechanical tissue properties that distinguish ankle cartilage from that of the knee. PMID:12911243

  7. Persistent currents and discharge patterns in rat hindlimb motoneurons.

    PubMed

    Hamm, Thomas M; Turkin, Vladimir V; Bandekar, Neha K; O'Neill, Derek; Jung, Ranu

    2010-09-01

    We report here the first direct measurements of persistent inward currents (PICs) in rat hindlimb motoneurons, obtained from ketamine-xylazine anesthetized rats during slow voltage ramps performed by single-electrode somatic voltage clamp. Most motoneurons expressed PICs and current-voltage (I-V) relations often contained a negative-slope region (NSR; 13/19 cells). PICs activated at -52.7 ± 3.89 mV, 9 mV negative to spike threshold. NSR onset was -44.2 ± 4.1 mV. PIC amplitudes were assessed by maximum inward currents measured relative to extrapolated leak current and to NSR-onset current. PIC conductance at potentials just positive to activation was assessed by the relative change in slope conductance (g(in)/g(leak)). PIC amplitudes varied widely; some exceeded 5 and 10 nA relative to current at NSR onset or leak current, respectively. PIC amplitudes did not vary significantly with input conductance, but PIC amplitudes normalized by recruitment current decreased with increasing input conductance. Similarly, g(in)/g(leak) decreased with increasing input conductance. Currents near resting potential on descending limbs of I-V relations were often outward, relative to ascending-limb currents. This residual outward current was correlated with increases in leak conductance on the descending limb and with input conductance. Excluding responses with accommodation, residual outward currents matched differences between recruitment and derecruitment currents, suggesting a role for residual outward current in frequency adaptation. Comparison of potentials for PIC activation and NSR onset with interspike trajectories during discharge demonstrated correspondence between PIC activation and frequency-current (f-I) range boundaries. Contributions of persistent inward and outward currents to motoneuron discharge characteristics are discussed. PMID:20592117

  8. Deletion of the BH3-only protein puma protects motoneurons from ER stress-induced apoptosis and delays motoneuron loss in ALS mice

    PubMed Central

    Kieran, Dairín; Woods, Ina; Villunger, Andreas; Strasser, Andreas; Prehn, Jochen H. M.

    2007-01-01

    BH3-only proteins couple diverse stress signals to the evolutionarily conserved mitochondrial apoptosis pathway. Previously, we reported that the activation of the BH3-only protein p53-up-regulated mediator of apoptosis (Puma) was necessary and sufficient for endoplasmic reticulum (ER) stress- and proteasome inhibition-induced apoptosis in neuroblastoma and other cancer cells. Defects in protein quality control have also been suggested to be a key event in ALS, a fatal neurodegenerative condition characterized by motoneuron degeneration. Using the SOD1G93A mouse model as well as human post mortem samples from ALS patients, we show evidence for increased ER stress and defects in protein degradation in motoneurons during disease progression. Before symptom onset, we detected a significant up-regulation of Puma in motoneurons of SOD1G93A mice. Genetic deletion of puma significantly improved motoneuron survival and delayed disease onset and motor dysfunction in SOD1G93A mice. However, it had no significant effect on lifespan, suggesting that other ER stress-related cell-death proteins or other factors, such as excitotoxicity, necrosis, or inflammatory injury, may contribute at later disease stages. Indeed, further experiments using cultured motoneurons revealed that genetic deletion of puma protected motoneurons against ER stress-induced apoptosis but showed no effect against excitotoxic injury. These findings demonstrate that a single BH3-only protein, the ER stress-associated protein Puma, plays an important role during the early stages of chronic neurodegeneration in vivo. PMID:18077368

  9. Anatomy of the ankle ligaments: a pictorial essay.

    PubMed

    Golanó, Pau; Vega, Jordi; de Leeuw, Peter A J; Malagelada, Francesc; Manzanares, M Cristina; Götzens, Víctor; van Dijk, C Niek

    2016-04-01

    Understanding the anatomy of the ankle ligaments is important for correct diagnosis and treatment. Ankle ligament injury is the most frequent cause of acute ankle pain. Chronic ankle pain often finds its cause in laxity of one of the ankle ligaments. In this pictorial essay, the ligaments around the ankle are grouped, depending on their anatomic orientation, and each of the ankle ligaments is discussed in detail. PMID:27052302

  10. Adaptation of cat motoneurons to sustained and intermittent extracellular activation.

    PubMed Central

    Spielmann, J M; Laouris, Y; Nordstrom, M A; Robinson, G A; Reinking, R M; Stuart, D G

    1993-01-01

    1. The main purpose of this study was to quantify the adaptation of spinal motoneurons to sustained and intermittent activation, using an extracellular route of stimulating current application to single test cells, in contrast to an intracellular route, as has been used previously. In addition, associations were tested between firing rate properties of the tested cells and other type (size)-related properties of these cells and their motor units. 2. Motoneurons supplying the medial gastrocnemius muscle of the deeply anaesthetized cat were stimulated for 240 s with microelectrodes which passed sustained extracellular current at 1.25 times the threshold for repetitive firing. Many cells were also tested following a rest period with intermittent 1 s current pulses (duration 600 ms) at the same relative stimulus strength. Cell discharge was assessed from the EMG of the motor unit innervated by the test neuron. The motoneurons and their motor units were assigned to four categories (i.e. types FF, FR, S and F; where F = FF + FR) based on conventional criteria. In all, twenty F (16 FF, 4 FR) and fourteen S cells were studied with sustained stimulation. Thirty of these cells (17 F, 13 S) and an additional two cells (1 F, 1 S) were studied with intermittent stimulation. 3. The mean threshold current required for sustained firing for a period of > or = 2 s was not significantly different for F and S cells. However, most of the other measured parameters of motoneuron firing differed significantly for these two cell groups. For example, at 1.25 times the threshold current for repetitive firing, the mean firing duration in response to 240 s of sustained activation was 123 +/- 88 s (+/- S.D.) for F cells vs. 233 +/- 19 s for S cells. These values were significantly longer than those from a comparable, previously reported study that employed intracellular stimulation. With intermittent stimulation, the firing durations of F and S cells were not significantly different from each

  11. Pseudoaneurysm of peroneal artery after ankle arthroscopy

    PubMed Central

    Battisti, Daniela; Oliva, Francesco; Tarantino, Umberto; Nicola, Maffulli

    2014-01-01

    Summary Background: ankle arthroscopy increased its role in the diagnosis and treatment of pathology of the ankle since 1970s. Although the benefits are well established, ankle arthroscopy is associated with a definite risk of complications, especially neurological. The incidence rate of vascular complication after anterior ankle arthroscopy has been reported. Methods: we review the literature on vascular complications after anterior ankle arthroscopy especially pseudoaneurysm and a case report of a peronal artery pseudoaneurysm was reported. Conclusion: vascular complications after an anterior ankle arthroscopy are extremely rare but orthopaedic surgeons should be wary of this chance. Among vascular complications after an anterior ankle arthroscopy, peroneal artery pseudoaneurysm to our knowledge never has been described until now. PMID:25332946

  12. Ankle inversion taping using kinesiology tape for treating medial ankle sprain in an amateur soccer player.

    PubMed

    Lee, Sun-Min; Lee, Jung-Hoon

    2015-07-01

    [Purpose] The purpose of this study was to report the effects of ankle inversion taping using kinesiology tape in a patient with a medial ankle sprain. [Subject] A 28-year-old amateur soccer player suffered a Grade 2 medial ankle sprain during a match. [Methods] Ankle inversion taping was applied to the sprained ankle every day for 2 months. [Results] His symptoms were reduced after ankle inversion taping application for 2 months. The self-reported function score, the reach distances in the Star Excursion Balance Test, and the weight-bearing ankle dorsiflexion were increased. [Conclusion] This study showed that ankle inversion taping using kinesiology tape may be an effective therapy for a patient with a medial ankle sprain. PMID:26311991

  13. Ankle inversion taping using kinesiology tape for treating medial ankle sprain in an amateur soccer player

    PubMed Central

    Lee, Sun-Min; Lee, Jung-Hoon

    2015-01-01

    [Purpose] The purpose of this study was to report the effects of ankle inversion taping using kinesiology tape in a patient with a medial ankle sprain. [Subject] A 28-year-old amateur soccer player suffered a Grade 2 medial ankle sprain during a match. [Methods] Ankle inversion taping was applied to the sprained ankle every day for 2 months. [Results] His symptoms were reduced after ankle inversion taping application for 2 months. The self-reported function score, the reach distances in the Star Excursion Balance Test, and the weight-bearing ankle dorsiflexion were increased. [Conclusion] This study showed that ankle inversion taping using kinesiology tape may be an effective therapy for a patient with a medial ankle sprain. PMID:26311991

  14. Syndesmotic ankle sprains in athletes.

    PubMed

    Williams, Glenn N; Jones, Morgan H; Amendola, Annunziato

    2007-07-01

    Ankle sprains are among the most common athletic injuries and represent a significant source of persistent pain and disability. Despite the high incidence of ankle sprains in athletes, syndesmosis injuries have historically been underdiagnosed, and assessment in terms of severity and optimal treatment has not been determined. More recently, a heightened awareness in sports medicine has resulted in more frequent diagnoses of syndesmosis injuries. However, there is a low level of evidence and a paucity of literature on this topic compared with lateral ankle sprains. As a result, no clear guidelines are available to help the clinician assess the severity of injury, choose an imaging modality to visualize the injury, make a decision in terms of operative versus nonoperative treatment, or decide when the athlete may return to play. Increased knowledge and understanding of these injuries by clinicians and researchers are essential to improve the prevention, diagnosis, and treatment of this significant condition. This review will discuss the anatomy, mechanism of injury, diagnosis, and treatment of syndesmosis sprains of the ankle while identifying controversies in management and topics for future research. PMID:17519439

  15. Extensor motoneurone properties are altered immediately before and during fictive locomotion in the adult decerebrate rat

    PubMed Central

    MacDonell, C W; Power, K E; Chopek, J W; Gardiner, K R; Gardiner, P F

    2015-01-01

    Key points This is the first report, in adult decerebrate rats, to examine intracellular hindlimb motoneurone properties during quiescence, fictive locomotion and a tonic period immediately before fictive locomotion that is characterized by increased peripheral nerve activity. It is shown for the first time during fictive locomotion that motoneurones become more responsive in the tonic period, suggesting that the motoneurone pool becomes primed before patterned motor output commences. Spike frequency adaptation exists in quiescence and during fictive locomotion during constant excitation with injected current but not during centrally driven fictive locomotion. Motoneurones within the extensor motor pool show changes in excitability even when they are not directly involved in locomotion. The data show increased responsiveness of motoneurones during locomotion via a lowered threshold for spike initiation and decreased rheobase. Abstract This study examined motoneurone properties during fictive locomotion in the adult rat for the first time. Fictive locomotion was induced via electrical stimulation of the mesencephalic locomotor region in decerebrate adult rats under neuromuscular blockade to compare basic and rhythmic motoneurone properties in antidromically identified extensor motoneurones during: (1) quiescence, before and after fictive locomotion; (2) the ‘tonic’ period immediately preceding locomotor-like activity, whereby the amplitude of peripheral flexor (peroneal) and extensor (tibial) nerves are increased but alternation has not yet occurred; and (3) locomotor-like episodes. Locomotion was identified by alternating flexor–extensor nerve activity, where the motoneurone either produced membrane oscillations consistent with a locomotor drive potential (LDP) or did not display membrane oscillation during alternating nerve activity. Cells producing LDPs were referred to as such, while those that did not were referred to as ‘idle’ motoneurones. LDP and

  16. Synaptic control of hindlimb motoneurones during three forms of the fictive scratch reflex in the turtle.

    PubMed Central

    Robertson, G A; Stein, P S

    1988-01-01

    1. The turtle spinal cord produces three forms of the fictive scratch reflex in response to tactile stimulation of sites on the body surface. Common to all three forms is the rhythmic alternation of activity between hip protractor and hip retractor motoneurones. Hip protractor motoneurone activity is monitored via nerves innervating the hip protractor muscle puboischiofemoralis internus pars anteroventralis (VP-HP). Hip retractor activity is monitored via nerves innervating several monoarticular hip retractor muscles, one hip adductor muscle, and several biarticular hip retractor-knee flexor muscles (HR-KF). Each form is characterized by the timing of activity of motoneurones innervating femorotibialis (FT-KE), a monoarticular knee extensor muscle, within this alternating cycle (Robertson, Mortin, Keifer & Stein, 1985). In the present study, intracellular recordings revealed a corresponding regulation of synaptic drive to knee extensor motoneurones with respect to the synaptic drive to the motoneurones innervating antagonist muscles of the hip. These patterns of synaptic activation give rise to the distinct motor pattern underlying each form of the scratch reflex. 2. VP-HP, HR-KF and FT-KE motoneurones all exhibited phasic depolarizing and hyperpolarizing changes in membrane voltage during the production of the rhythmic motor patterns underlying each stratch form. Membrane depolarization is caused by synaptic excitation (EPSPs) and gives rise to motoneurone discharge. Hyperpolarization is primarily the result of postsynaptic inhibition (IPSPs) mediated by an increased conductance of chloride ions (Cl-) and ensures motor pool quiescence during antagonist activation. 3. VP-HP motoneurones depolarized during activation of the VP-HP motor pool and hyperpolarized during activation of the HR-KF motor pool. HR-KF motoneurones depolarized during activation of the HR-KF motor pool and hyperpolarized during activation of the VP-HP motor pool. In many cases, the amplitude of

  17. Postnatal electrical and morphological abnormalities in lumbar motoneurons from transgenic mouse models of amyotrophic lateral sclerosis.

    PubMed

    Amendola, J; Gueritaud, J P; Lamotte d'Incamps, B; Bories, C; Liabeuf, S; Allene, C; Pambo-Pambo, A; Durand, J

    2007-11-01

    Antidromically identified lumbar motoneurons intracellularly recorded in the entire brainstem/spinal cord preparation isolated from SOD1(G85R) postnatal mice (P3-P10) were labelled with neurobiotin and fully reconstructed in 3D from serial sections in order to analyse their morphology. This staining procedure revealed differences between WT and SOD1(G85R) dendritic trees for most metric and topologic parameters analyzed. A highly complex morphology of SOD1(G85R) motoneurons dendrites (increased number of branching points and terminations) was found and the dendritic trees were longer compared to the WT motoneurons. These morphological changes observed in P8-P9 motoneurons mice occurred concomitantly with a decrease in the input resistance and gain. During electrophysiological recordings, four patterns of discharge were observed in response to ramp stimulations, that were equally distributed in WT and SOD1(G85R) motoneurons. In slice preparation, whole cell patch-clamp recordings made from developing motoneurons in SOD1(G85R) and double transgenic SOD1(G93A)/Hb9-eGFP mice showed that Riluzole, a blocker of persistent inward sodium conductance, altered the repetitive firing in a similar way for the 2 strains. These results show that the SOD1 mutations linked to familial ALS alter the development of the electrical and morphological properties of lumbar motoneurons. PMID:18075124

  18. Axotomized neonatal motoneurons overexpressing the bcl2 proto-oncogene retain functional electrophysiological properties.

    PubMed Central

    Alberi, S; Raggenbass, M; de Bilbao, F; Dubois-Dauphin, M

    1996-01-01

    Bcl2 overexpression prevents axotomy-induced neuronal death of neonatal facial motoneurons, as defined by morphological criteria. However, the functional properties of these surviving lesioned transgenic neurons are unknown. Using transgenic mice overexpressing the protein Bcl2, we have investigated the bioelectrical properties of transgenic facial motoneurons from 7 to 20 days after neonatal unilateral axotomy using brain-stem slices and whole cell patch-clamp recording. Nonaxotomized facial motoneurons from wild-type and transgenic mice had similar properties; they had an input resistance of 38 +/- 6 M omega and fired repetitively after injection of positive current pulses. When cells were voltage-clamped at or near their resting membrane potential, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartic acid (NMDA), or vasopressin generated sustained inward currents. In transgenic axotomized mice, facial motoneurons could be found located ipsilaterally to the lesion; they had an input resistance of 150 +/- 30 M omega, indicating that they were smaller in size, fired repetitively, and were also responsive to AMPA, NMDA, and vasopressin. Morphological measurements achieved 1 week after the lesion have shown that application of brain-derived neurotrophic factor prevented the reduction in size of axotomized transgenic motoneurons. These data indicate that Bcl2 not only prevents morphological apoptotic death of axotomized neonatal transgenic motoneurons but also permits motoneurons to conserve functional electrophysiological properties. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:8633001

  19. Total ankle replacement. The results in 200 ankles.

    PubMed

    Wood, P L R; Deakin, S

    2003-04-01

    Between 1993 and 2000 we implanted 200 cementless, mobile-bearing STAR total ankle replacements. None was lost to follow-up for reasons other than the death of a patient. The mean follow-up was for 46 months (24 to 101). A complication requiring further surgery developed in eight ankles and 14 were revised or fused. The cumulative survival rate at five years was 92.7% (95% CI 86.6 to 98.8) with time to decision to revision or fusion as an endpoint. The most frequent complications were delayed wound healing and fracture of a malleolus. These became less common with experience of the operation. The radiological appearance of the interface of the tibial implant was significantly related to its operative fit and to the type of bioactive coating. PMID:12729104

  20. A systematic review on ankle injury and ankle sprain in sports.

    PubMed

    Fong, Daniel Tik-Pui; Hong, Youlian; Chan, Lap-Ki; Yung, Patrick Shu-Hang; Chan, Kai-Ming

    2007-01-01

    This article systematically reviews epidemiological studies on sports injury from 1977 to 2005 in which ankle injury was included. A total of 227 studies reporting injury pattern in 70 sports from 38 countries were included. A total of 201,600 patients were included, with 32,509 ankle injuries. Ankle injury information was available from 14,098 patients, with 11 847 ankle sprains. Results show that the ankle was the most common injured body site in 24 of 70 included sports, especially in aeroball, wall climbing, indoor volleyball, mountaineering, netball and field events in track and field. Ankle sprain was the major ankle injury in 33 of 43 sports, especially in Australian football, field hockey, handball, orienteering, scooter and squash. In sports injuries throughout the countries studied, the ankle was the second most common injured body site after the knee, and ankle sprain was the most common type of ankle injury. The incidence of ankle injury and ankle sprain was high in court games and team sports, such as rugby, soccer, volleyball, handball and basketball. This systematic review provides a summary of the epidemiology of ankle injury in sports. PMID:17190537

  1. Neuroprotective effects of NGF, BDNF, NT-3 and GDNF on axotomized extraocular motoneurons in neonatal rats.

    PubMed

    Morcuende, S; Muñoz-Hernández, R; Benítez-Temiño, B; Pastor, A M; de la Cruz, R R

    2013-10-10

    Neurotrophic factors delivered from target muscles are essential for motoneuronal survival, mainly during development and early postnatal maturation. It has been shown that the disconnection between motoneurons and their innervated muscle by means of axotomy produces a vast neuronal death in neonatal animals. In the present work, we have evaluated the effects of different neurotrophic factors on motoneuronal survival after neonatal axotomy, using as a model the motoneurons innervating the extraocular eye muscles. With this purpose, neonatal rats were monocularly enucleated at the day of birth (postnatal day 0) and different neurotrophic treatments (NGF, BDNF, NT-3, GDNF and the mixture of BDNF+GDNF) were applied intraorbitally by means of a Gelfoam implant (a single dose of 5 μg of each factor). We first demonstrated that extraocular eye muscles of neonatal rats expressed these neurotrophic factors and therefore constituted a natural source of retrograde delivery for their innervating motoneurons. By histological and immunocytochemical methods we determined that all treatments significantly rescued extraocular motoneurons from axotomy-induced cell death. For the dose used, NGF and GDNF were the most potent survival factors for these motoneurons, followed by BDNF and lastly by NT-3. The simultaneous administration of BDNF and GDNF did not increase the survival-promoting effects above those obtained by GDNF alone. Interestingly, the rescue effects of all neurotrophic treatments persisted even 30 days after lesion. The administration of these neurotrophic factors, with the exception of NT-3, also prevented the loss of the cholinergic phenotype observed by 10 days after axotomy. At the dosage applied, NGF and GDNF were revealed again as the most effective neuroprotective agents against the axotomy-induced decrease in ChAT. Two remarkable findings highlighted in the present work that contrasted with other motoneuronal types after neonatal axotomy: first, the extremely

  2. Absence of synergy for monosynaptic Group I inputs between abdominal and internal intercostal motoneurons

    PubMed Central

    Ford, T. W.; Meehan, C. F.

    2014-01-01

    Internal intercostal and abdominal motoneurons are strongly coactivated during expiration. We investigated whether that synergy was paralleled by synergistic Group I reflex excitation. Intracellular recordings were made from motoneurons of the internal intercostal nerve of T8 in anesthetized cats, and the specificity of the monosynaptic connections from afferents in each of the two main branches of this nerve was investigated. Motoneurons were shown by antidromic excitation to innervate three muscle groups: external abdominal oblique [EO; innervated by the lateral branch (Lat)], the region of the internal intercostal muscle proximal to the branch point (IIm), and muscles innervated from the distal remainder (Dist). Strong specificity was observed, only 2 of 54 motoneurons showing excitatory postsynaptic potentials (EPSPs) from both Lat and Dist. No EO motoneurons showed an EPSP from Dist, and no IIm motoneurons showed one from Lat. Expiratory Dist motoneurons fell into two groups. Those with Dist EPSPs and none from Lat (group A) were assumed to innervate distal internal intercostal muscle. Those with Lat EPSPs (group B) were assumed to innervate abdominal muscle (transversus abdominis or rectus abdominis). Inspiratory Dist motoneurons (assumed to innervate interchondral muscle) showed Dist EPSPs. Stimulation of dorsal ramus nerves gave EPSPs in 12 instances, 9 being in group B Dist motoneurons. The complete absence of heteronymous monosynaptic Group I reflex excitation between muscles that are synergistically activated in expiration leads us to conclude that such connections from muscle spindle afferents of the thoracic nerves have little role in controlling expiratory movements but, where present, support other motor acts. PMID:24920027

  3. Resistance of extraocular motoneuron terminals to effects of amyotrophic lateral sclerosis sera

    NASA Technical Reports Server (NTRS)

    Mosier, D. R.; Siklos, L.; Appel, S. H.

    2000-01-01

    In sporadic ALS (s-ALS), axon terminals contain increased intracellular calcium. Passively transferred sera from patients with s-ALS increase intracellular calcium in spinal motoneuron terminals in vivo and enhance spontaneous transmitter release, a calcium-dependent process. In this study, passive transfer of s-ALS sera increased spontaneous release from spinal but not extraocular motoneuron terminals, suggesting that the resistance to physiologic abnormalities induced by s-ALS sera in mice parallels the resistance of extraocular motoneurons to dysfunction and degeneration in ALS.

  4. The parallel growth of motoneuron axons with the dorsal aorta depends on Vegfc/Vegfr3 signaling in zebrafish

    PubMed Central

    Kwon, Hyouk-Bum; Fukuhara, Shigetomo; Asakawa, Kazuhide; Ando, Koji; Kashiwada, Takeru; Kawakami, Koichi; Hibi, Masahiko; Kwon, Young-Guen; Kim, Kyu-Won; Alitalo, Kari; Mochizuki, Naoki

    2013-01-01

    Blood vessels and neurons grow often side by side. However, the molecular and cellular mechanisms underlying their parallel development remain unclear. Here, we report that a subpopulation of secondary motoneurons extends axons ventrally outside of the neural tubes and rostrocaudally as a fascicle beneath the dorsal aorta (DA) in zebrafish. We tried to clarify the mechanism by which these motoneuron axons grow beneath the DA and found that Vegfc in the DA and Vegfr3 in the motoneurons were essential for the axon growth. Forced expression of either Vegfc in arteries or Vegfr3 in motoneurons resulted in enhanced axon growth of motoneurons over the DA. Both vegfr3 morphants and vegfc morphants lost the alignment of motoneuron axons with DA. In addition, forced expression of two mutant forms of Vegfr3 in motoneurons, potentially trapping endogenous Vegfc, resulted in failure of growth of motoneuron axons beneath the DA. Finally, a vegfr3 mutant fish lacked the motoneuron axons beneath the DA. Collectively, Vegfc from the preformed DA guides the axon growth of secondary motoneurons. PMID:24046321

  5. The prognosis of ankle sprains.

    PubMed

    de Bie, R A; de Vet, H C; van den Wildenberg, F A; Lenssen, T; Knipschild, P G

    1997-05-01

    We developed a new diagnostic tool for predicting the severity of ankle sprains just after injury. Since hard data obtained by diagnostic imaging techniques are still imperfect, we decided to use data from individual medical history and signs and symptoms that are part of the admission routine. During a three month-period data were collected on thirty-five patients with lateral ankle sprains who visited the first aid department of the University Hospital of Maastricht. Assessments took place at admission and at two and four weeks after injury. Assessors were the first-aid physician, a physiotherapist and the patient. Dependent variables were healed ankle in two and four weeks. Predicting variables were the data obtained at admission by the physician, the physiotherapist and the patient. The ability to predict outcome after two and four weeks was determined in a bivariate analysis, followed by logistic modelling. Accurate prediction of recovery time at admission appeared to be possible. Best two weeks predictor was the modified function score, an accuracy of 97% was achieved. Four weeks prediction was most accurate when function score was used together with the report mark from the doctor and the palpation score (accuracy of 81%). PMID:9231846

  6. Outcome of ankle arthrodesis in posttraumatic arthritis

    PubMed Central

    Gowda, BS Narayana; Kumar, J Mohan

    2012-01-01

    Background: Ankle arthrodesis is still a gold standard salvage procedure for the management of ankle arthritis. There are several functional and mechanical benefits of ankle arthrodesis, which make it a viable surgical procedure in the management of ankle arthritis. The functional outcomes following ankle arthrodesis are not very well known. The purpose of this study was to perform a clinical and radiographic evaluation of ankle arthrodesis in posttraumatic arthritis performed using Charnley's compression device. Materials and Methods: Between January 2006 and December 2009 a functional assessment of 15 patients (10 males and 5 females) who had undergone ankle arthrodesis for posttraumatic arthritis and/or avascular necrosis (AVN) talus (n=6), malunited bimalleolar fracture (n=4), distal tibial plafond fractures (n=3), medial malleoli nonunion (n=2). All the patients were assessed clinically and radiologically after an average followup of 2 years 8 months (range 1–5.7 years). Results: All patients had sound ankylosis and no complications related to the surgery. Scoring the patients with the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot scale, we found that 11 of the 15 had excellent results, two had good, and two showed fair results. They were all returned to their preinjury activities. Conclusion: We conclude that, the ankle arthrodesis can still be considered as a standard procedure in ankle arthritis. On the basis of these results, patients should be counseled that an ankle fusion will help to relieve pain and to improve overall function. Still, one should keep in mind that it is a salvage procedure that will cause persistent alterations in gait with a potential for deterioration due to the development of subtalar arthritis. PMID:22719119

  7. Find an Orthopaedic Foot and Ankle MD/DO

    MedlinePlus

    ... AOFAS / FootCareMD / Find a Surgeon Find an Orthopaedic Foot & Ankle Surgeon Page Content The Orthopaedic Distinction Who are Orthopaedic Foot & Ankle Surgeons? Orthopaedic foot and ankle surgeons are ...

  8. Total Ankle Arthroplasty: An Imaging Overview

    PubMed Central

    Kim, Da-Rae; Potter, Hollis G.; Li, Angela E.; Chun, Ka-Young; Jung, Yoon Young; Kim, Jin-Su; Young, Ki-Won

    2016-01-01

    With advances in implant technology, total ankle arthroplasty (TAA) has become an increasingly popular alternative to arthrodesis for the management of end-stage ankle arthritis. However, reports in the literature do not focus on the imaging features of TAA. Through a literature review, we demonstrate basic design features of the current ankle arthroplasty system, and the normal and abnormal postoperative imaging features associated with such devices. Pre- and postoperative evaluations of ankle arthroplasty mainly include radiography; in addition, computed tomography and magnetic resonance imaging provide further characterization of imaging abnormalities. Familiarization with multimodal imaging features of frequent procedural complications at various postoperative intervals is important in radiological practice. PMID:27134529

  9. Surgical treatment of the arthritic varus ankle.

    PubMed

    Easley, Mark E

    2012-12-01

    Within the past several years, the arthritic varus ankle has been addressed extensively in Foot and Ankle Clinics, with numerous excellent reviews by particularly knowledgeable authors. To support these outstanding contributions, this article provides a practical approach to this challenging constellation of foot and ankle abnormalities. Varus ankle arthritis exists on a continuum that prompts the treating surgeon to be familiar with a spectrum of surgical solutions, including joint-sparing realignment, arthroplasty, and arthrodesis. Each of these treatment options is addressed with several expanded case examples and supports the management approaches with the available pertinent literature. PMID:23158376

  10. Which ankle fractures require syndesmotic stabilization?

    PubMed

    van den Bekerom, Michel P J; Lamme, Bas; Hogervorst, Mike; Bolhuis, Hugo W

    2007-01-01

    Syndesmotic ruptures associated with ankle fractures are most commonly caused by external rotation of the foot, eversion of the talus within the ankle mortise, and excessive dorsiflexion. The distal tibiofibular syndesmosis consists of the anterior inferior tibiofibular ligament, posterior inferior tibiofibular ligament, and interosseous ligament, and it is essential for stability of the ankle mortise. Despite the numerous biomechanical and clinical studies pertaining to ankle fractures, there are no uniform recommendations regarding the use of the syndesmotic screw for specific injury patterns and fracture types. The objective of this review was to formulate recommendations for clinical practice related to the use of syndesmotic screw placement. PMID:17980843

  11. The relationship between lateral ankle sprain and ankle tendinitis in ballet dancers.

    PubMed

    Ritter, Stephanie; Moore, Marjorie

    2008-01-01

    The lateral ligament complex of the ankle is the most frequently injured structure in the body. Although most simple ankle sprains do not result in long-term disability, a significant number do not completely resolve, leading to residual symptoms that may persist for years. The most commonly reported symptoms, particularly among athletes, include instability, re-injury, and tendinitis. Ballet dancers are a combination of artist and high-performance athlete; consequently, they are subjected to the same types of injuries as other athletes, including lateral ankle sprains and their sequelae. Furthermore, ballet dancers perform in unusual positions such as en pointe, which places the ankle in extreme plantar flexion, requiring stabilization by surrounding muscles. Dancers' extraordinary performance demands place them at risk for other ankle injuries as well, including inflammation ofseveral tendons, especially the peroneals. This report reviews the relevant literature to characterize the scope of lateral ankle sprains and sequelae, discuss the importance of the peroneal muscles in ankle stability, and explore a relationship between lateral ankle sprain and ankle tendinitis in ballet dancers. Informal interviews were conducted with physical therapists who specialize in treating ballet dancers, providing a clinical context for this report. An extensive review of the literature was conducted, including electronic databases, reference lists from papers, and relevant reference texts. Numerous studies have investigated ankle sprains and residual complaints; nearly all report that lateral ankle sprains commonly lead to chronic ankle instability. Studies exploring ankle stability have demonstrated that the peroneal muscles play a crucial role in ankle stabilization; EMG studies confirm they are the first to contract during ankle inversion stress. The dancer's need for exceptional ankle stabilization may lead to peroneal overuse and tendinitis. Studies have linked peroneal

  12. Naturally occurring somatic motoneuron death in a teleost angelfish, Pterophyllum scalare.

    PubMed

    Sakamoto, H; Yoshida, M; Uematsu, K

    1999-05-28

    Naturally occurring somatic motoneuron death in a teleost angelfish, Pterophyllum scalare, was investigated histochemically and electron microscopically. The number of motor axons in the ventral root, which corresponds to the motoneuron number in spinal hemisegment, was rapidly increased beyond the adult value within 3 days after hatching, and then decreased to reach the adult value within a few weeks. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) histochemistry, which detects fragmented nuclear DNA characteristic to apoptotic cells, showed that the apoptotic cells are located in the motor column of the cord in the larvae at specific developmental stages. Electron microscopic observations of the spinal cells further confirmed the motoneuron apoptosis. The present data suggest that the massive death of somatic motoneurons at certain ontogenic stages which has been known to occur in higher vertebrates also takes place in fish. PMID:10400233

  13. Effect of quercetine on survival and morphological properties of cultured embryonic rat spinal motoneurones.

    PubMed

    Ternaux, Jean-Pierre; Portalier, Paule

    2002-10-25

    Quercetine a flavonoid compound present in many plants and in the extract of Ginkgo biloba was shown to enhance the survival of purified rat spinal embryonic motoneurones, sampled at day embryonic 15 and maintained in culture for several days. Survival of embryonic spinal motoneurones is dose dependent and concentrations of quercetine ranging from 1 to 10 microM increase by 25% the number of living motoneurones in the culture. Excepted a slight significant decrease in the number of branches at day 3 and a small reduction of total neuritic length, no drastic changes in the motoneurones morphologies were observed in presence of quercetine. Results are discussed in term of neuronal protective effect of quercetine. PMID:12377378

  14. Altered calcium homeostasis in spinal motoneurons but not in oculomotor neurons of SOD-1 knockout mice.

    PubMed

    Siklós, L; Engelhardt, J I; Reaume, A G; Scott, R W; Adalbert, R; Obál, I; Appel, S H

    2000-05-01

    SOD-1-deficient mice demonstrate no loss of motoneurons but are still vulnerable to axotomy and ischemic insults. To investigate possible reasons for vulnerability of motoneuron populations, we studied changes in ultrastructural calcium distribution during maturation in spinal- and oculomotor neurons in SOD-1(-/-) mice. Between 3 and 11 months the cytoplasmic component of the intracellular calcium changed at a lower rate in spinal motoneurons and motor axon terminals in the interosseus muscle of SOD-1(-/-) animals compared to wild-type controls. No such dissimilarities were noted in the oculomotor system, or in mitochondrial calcium contents of either cell type. These data suggest that the lack of SOD-1 may be associated with vulnerability to insult by depletion of non-mitochondrial calcium stores selectively in motoneurons lacking parvalbumin and/or calbindin D28K. PMID:10805095

  15. Inhibition of motoneurons during the cutaneous silent period in the spinal cord of the turtle.

    PubMed

    Guzulaitis, Robertas; Hounsgaard, Jorn; Alaburda, Aidas

    2012-07-01

    The transient suppression of motor activity in the spinal cord after a cutaneous stimulus is termed the cutaneous silent period (CSP). It is not known if CSP is due to suppression of the premotor network or direct inhibition of motoneurons. This issue was examined by intracellular recordings from motoneurons in the isolated carapace-spinal cord preparation from adult turtles during rhythmic scratch-like reflex. Electrical stimulation of cutaneous nerves induced CSP-like suppression of motor nerve firing during rhythmic network activity. The stimulus that generated the CSP-like suppression of motor activity evokes a polysynaptic compound synaptic potential in motoneurons and suppressed their firing. This compound synaptic potential was hyperpolarizing near threshold for action potentials and was associated with a substantial increase in conductance during the CSP in the motor pool. These results show that direct postsynaptic inhibition of motoneurons contributes to the CSP. PMID:22580573

  16. Motoneuron Programmed Cell Death in Response to proBDNF

    PubMed Central

    Taylor, AR; Gifondorwa, DJ; Robinson, MB; Strupe, JL; Prevette, D; Johnson, JE; Hempstead, BL; Oppenheim, RW; Milligan, CE

    2011-01-01

    Motoneurons (MN) as well as most neuronal populations undergo a temporally and spatially specific period of programmed cell death (PCD). Several factors have been considered to regulate the survival of MNs during this period, including availability of muscle-derived trophic support and activity. The possibility that target-derived factors may also negatively regulate MN survival has been considered, but not pursued. Neurotrophin precursors, through their interaction with p75NTR and sortilin receptors have been shown to induce cell death during development and following injury in the CNS. In this study, we find that muscle cells produce and secrete proBDNF. ProBDNF through its interaction with p75NTR and sortilin, promotes a caspase-dependent death of MNs in culture. We also provide data to suggest that proBDNF regulates MN PCD during development in vivo. PMID:21834083

  17. RNA content in spinal cord motoneurons during hypokinesia

    NASA Technical Reports Server (NTRS)

    Gorbunova, A. V.

    1980-01-01

    The effect of a diminished motor activity of rats upon the ribonucleic and (RNA) content in a single isolated motoneuron of frontal of their spinal cord was studied. Within a 1 to 30 day exposure of rats to the hypokinetic conditions, RNA content was found to decrease on the 1st, 3rd, and 5th day and to return to the initial level by the 7th day. No changes in RNA content were observed during the subsequent stages of the xperiments. The volume of the nerve cells declined on the 3rd and 5th day, whereas RNA concentration reduced on the 1st, 3rd, 5th, and 30th day.

  18. Influence of asphyxia upon the responses of spinal motoneurons.

    PubMed

    LLOYD, D P C

    1953-05-01

    Observations have been made upon asphyxial and postasphyxial changes in the electrical responses of motoneurons to antidromic stimulation. Analysis has been aided by the use of a simple method for locating conduction blocks in the circumstances of volume conduction. Asphyxiation has been produced by suspending artificial ventilation. Regular practice has been to restore ventilation immediately after complete conduction block is established. This has permitted study of the postasphyxial state, but not of the effects of prolonged asphyxiation with the latter of which this paper is not concerned. With asphyxiation produced in the manner outlined a latent period of approximately 1 minute precedes the onset of asphyxial change. The initial change, to judge by the work of others (6, 7), is beginning central depolarization. At the same time there is a severe loss of somatic after-potential (Fig. 1). Through this loss the dendrites acquire the ability to carry two volleys in rapid succession (Fig. 13). These changes appear to reach completion within approximately 30 seconds. There follows a period of convulsive activity during which reciprocal amplitude changes in the response of axons and dendrites prove that a fluctuation in somatic responsivity is taking place (Fig. 11). Intermittent impulse discharge in ventral roots is seen (Fig. 1). Conduction block may be developing slowly throughout the period of convulsive activity (Fig. 11). Frequently there is a rather definite instant at which convulsive activity ceases and a rapid development of block begins. Usually the recorded amplitude of the dendritic response then increases to a peak (the preterminal increment) before final disappearance (Figs. 9 to 11, 13 to 15). A variety of reasons has been advanced to show that this preterminal increment represents not increased response, but rather a developing block (Figs. 11 to 13). When fully established, asphyxial block is located at the junction of the initial and myelinated

  19. Insulin-like growth factors: putative muscle-derived trophic agents that promote motoneuron survival.

    PubMed

    Neff, N T; Prevette, D; Houenou, L J; Lewis, M E; Glicksman, M A; Yin, Q W; Oppenheim, R W

    1993-12-01

    Treatment of chick embryos in ovo with IGF-I during the period of normal, developmentally regulated neuronal death (embryonic days 5-10) resulted in a dose-dependent rescue of a significant number of lumbar motoneurons from degeneration and death. IGF-II and two variants of IGF-I with reduced affinity for IGF binding proteins, des(1-3) IGF-I and long R3 IGF-I, also elicited enhanced survival of motoneurons equal to that seen in IGF-I-treated embryos. IGF-I did not enhance mitogenic activity in motoneuronal populations when applied to embryos during the period of normal neuronal proliferation (E2-5). Treatment of embryos with IGF-I also reduced two types of injury-induced neuronal death. Following either deafferentation or axotomy, treatment of embryos with IGF-I rescued approximately 75% and 50%, respectively, of the motoneurons that die in control embryos as a result of these procedures. Consistent with the survival-promoting activity on motoneurons in ovo, IGF-I, -II, and des(1-3) IGF-I elevated choline acetyltransferase activity in embryonic rat spinal cord cultures, with des(1-3) IGF-I demonstrating 2.5 times greater potency than did IGF-I. A single addition of IGF-I at culture initiation resulted in the maintenance of 80% of the initial ChAT activity for up to 5 days, during which time ChAT activity in untreated control cultures fell to 9%. In summary, these results demonstrate clear motoneuronal trophic activity for the IGFs. These findings, together with previous reports that IGFs are synthesized in muscle and may participate in motoneuron axonal regeneration and sprouting, indicate that these growth factors may have an important role in motoneuron development, maintenance, and recovery from injury. PMID:8301266

  20. Motoneuron axon pathfinding errors in zebrafish: Differential effects related to concentration and timing of nicotine exposure

    SciTech Connect

    Menelaou, Evdokia; Paul, Latoya T.; Perera, Surangi N.; Svoboda, Kurt R.

    2015-04-01

    Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMNs). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15–30 μM). Previous work showed that the paralytic mutant zebrafish known as sofa potato exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at different developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window. - Highlights: • Embryonic nicotine exposure can specifically affect secondary motoneuron axons in a dose-dependent manner.

  1. Functional recovery after cervical spinal cord injury: Role of neurotrophin and glutamatergic signaling in phrenic motoneurons.

    PubMed

    Gill, Luther C; Gransee, Heather M; Sieck, Gary C; Mantilla, Carlos B

    2016-06-01

    Cervical spinal cord injury (SCI) interrupts descending neural drive to phrenic motoneurons causing diaphragm muscle (DIAm) paralysis. Recent studies using a well-established model of SCI, unilateral spinal hemisection of the C2 segment of the cervical spinal cord (SH), provide novel information regarding the molecular and cellular mechanisms of functional recovery after SCI. Over time post-SH, gradual recovery of rhythmic ipsilateral DIAm activity occurs. Recovery of ipsilateral DIAm electromyogram (EMG) activity following SH is enhanced by increasing brain-derived neurotrophic factor (BDNF) in the region of the phrenic motoneuron pool. Delivery of exogenous BDNF either via intrathecal infusion or via mesenchymal stem cells engineered to release BDNF similarly enhance recovery. Conversely, recovery after SH is blunted by quenching endogenous BDNF with the fusion-protein TrkB-Fc in the region of the phrenic motoneuron pool or by selective inhibition of TrkB kinase activity using a chemical-genetic approach in TrkB(F616A) mice. Furthermore, the importance of BDNF signaling via TrkB receptors at phrenic motoneurons is highlighted by the blunting of recovery by siRNA-mediated downregulation of TrkB receptor expression in phrenic motoneurons and by the enhancement of recovery evident following virally-induced increases in TrkB expression specifically in phrenic motoneurons. BDNF/TrkB signaling regulates synaptic plasticity in various neuronal systems, including glutamatergic pathways. Glutamatergic neurotransmission constitutes the main inspiratory-related, excitatory drive to motoneurons, and following SH, spontaneous neuroplasticity is associated with increased expression of ionotropic N-methyl-d-aspartate (NMDA) receptors in phrenic motoneurons. Evidence for the role of BDNF/TrkB and glutamatergic signaling in recovery of DIAm activity following cervical SCI is reviewed. PMID:26506253

  2. Extensor motoneurone properties are altered immediately before and during fictive locomotion in the adult decerebrate rat.

    PubMed

    MacDonell, C W; Power, K E; Chopek, J W; Gardiner, K R; Gardiner, P F

    2015-05-15

    This study examined motoneurone properties during fictive locomotion in the adult rat for the first time. Fictive locomotion was induced via electrical stimulation of the mesencephalic locomotor region in decerebrate adult rats under neuromuscular blockade to compare basic and rhythmic motoneurone properties in antidromically identified extensor motoneurones during: (1) quiescence, before and after fictive locomotion; (2) the 'tonic' period immediately preceding locomotor-like activity, whereby the amplitude of peripheral flexor (peroneal) and extensor (tibial) nerves are increased but alternation has not yet occurred; and (3) locomotor-like episodes. Locomotion was identified by alternating flexor-extensor nerve activity, where the motoneurone either produced membrane oscillations consistent with a locomotor drive potential (LDP) or did not display membrane oscillation during alternating nerve activity. Cells producing LDPs were referred to as such, while those that did not were referred to as 'idle' motoneurones. LDP and idle motoneurones during locomotion had hyperpolarized spike threshold (Vth ; LDP: 3.8 mV; idle: 5.8 mV), decreased rheobase and an increased discharge rate (LDP: 64%; idle: 41%) during triangular ramp current injection even though the frequency-current slope was reduced by 70% and 55%, respectively. Modulation began in the tonic period immediately preceding locomotion, with a hyperpolarized Vth and reduced rheobase. Spike frequency adaptation did not occur in spiking LDPs or firing generated from sinusoidal current injection, but occurred during a sustained current pulse during locomotion. Input conductance showed no change. Results suggest motoneurone modulation occurs across the pool and is not restricted to motoneurones engaged in locomotion. PMID:25809835

  3. Marked and variable inhibition by chemical fixation of cytochrome oxidase and succinate dehydrogenase in single motoneurons

    NASA Technical Reports Server (NTRS)

    Chalmers, G. R.; Edgerton, V. R.

    1989-01-01

    The effect of tissue fixation on succinate dehydrogenase and cytochrome oxidase activity in single motoneurons of the rat was demonstrated using a computer image processing system. Inhibition of enzyme activity by chemical fixation was variable, with some motoneurons being affected more than others. It was concluded that quantification of enzymatic activity in chemically fixed tissue provides an imprecise estimate of enzyme activities found in fresh-frozen tissues.

  4. Nitrergic innervation of trigeminal and hypoglossal motoneurons in the cat.

    PubMed

    Pose, Ines; Fung, Simon; Sampogna, Sharon; Chase, Michael H; Morales, Francisco R

    2005-04-11

    The present study was undertaken to determine the location of trigeminal and hypoglossal premotor neurons that express neuronal nitric oxide synthase (nNOS) in the cat. Cholera toxin subunit b (CTb) was injected into the trigeminal (mV) or the hypoglossal (mXII) motor nuclei in order to label the corresponding premotor neurons. CTb immunocytochemistry was combined with NADPH-d histochemistry or nNOS immunocytochemistry to identify premotor nitrergic (NADPH-d(+)/CTb(+) or nNOS(+)/ CTb(+) double-labeled) neurons. Premotor trigeminal as well as premotor hypoglossal neurons were located in the ventro-medial medullary reticular formation in a region corresponding to the nucleus magnocellularis (Mc) and the ventral aspect of the nucleus reticularis gigantocellularis (NRGc). Following the injection of CTb into the mV, this region was found to contain a total of 60 +/- 15 double-labeled neurons on the ipsilateral side and 33 +/- 14 on the contralateral side. CTb injections into the mXII resulted in 40 +/- 17 double-labeled neurons in this region on the ipsilateral side and 16 +/- 5 on the contralateral side. Thus, we conclude that premotor trigeminal and premotor hypoglossal nitrergic cells coexist in the same medullary region. They are colocalized with a larger population of nitrergic cells (7200 +/- 23). Premotor neurons in other locations did not express nNOS. The present data demonstrate that a population of neurons within the Mc and the NRGc are the source of the nitrergic innervation of trigeminal and hypoglossal motoneurons. Based on the characteristics of nitric oxide actions and its diffusibility, we postulate that these neurons may serve to synchronize the activity of mV and mXII motoneurons. PMID:15804497

  5. Reversal of the late phase of spike frequency adaptation in cat spinal motoneurons during fictive locomotion.

    PubMed

    Brownstone, Robert M; Krawitz, Sherry; Jordan, Larry M

    2011-03-01

    In spinal motoneurons, late spike frequency adaptation (SFA) is defined as the slowing of the firing rate over tens of seconds and can be seen during sustained or intermittent current injection. Although the function of late SFA is not known, it may result in a decrease in force production over time, or muscle fatigue. Because locomotion can persist for long periods of time without fatigue, late SFA was studied using intracellular recordings from adult cat motoneurons during fictive locomotion. Of eight lumbar motoneurons studied, all showed late adaptation during control conditions, but none demonstrated late adaptation during locomotor activity. The most consistent properties that correlated with the presence or absence of late SFA were those related to availability of fast, inactivating sodium channels, particularly action potential rate of rise. Evidence of the reversal of late SFA during locomotion was present for several minutes following locomotor trials, consistent with the suggestion that SFA is modulated through slow metabotropic pathways. The abolition of late adaptation in spinal motoneurons during fictive locomotion is an example of a state-dependent change in the "intrinsic" properties of mammalian motoneurons. This change contributes to increased excitability of motoneurons during locomotion and results in robust firing during sustained locomotion. PMID:21177992

  6. Mutant SOD1-expressing astrocytes release toxic factors that trigger motoneuron death by inducing hyperexcitability.

    PubMed

    Fritz, Elsa; Izaurieta, Pamela; Weiss, Alexandra; Mir, Franco R; Rojas, Patricio; Gonzalez, David; Rojas, Fabiola; Brown, Robert H; Madrid, Rodolfo; van Zundert, Brigitte

    2013-06-01

    Amyotrophic lateral sclerosis (ALS) is a devastating paralytic disorder caused by dysfunction and degeneration of motoneurons starting in adulthood. Recent studies using cell or animal models document that astrocytes expressing disease-causing mutations of human superoxide dismutase 1 (hSOD1) contribute to the pathogenesis of ALS by releasing a neurotoxic factor(s). Neither the mechanism by which this neurotoxic factor induces motoneuron death nor its cellular site of action has been elucidated. Here we show that acute exposure of primary wild-type spinal cord cultures to conditioned medium derived from astrocytes expressing mutant SOD1 (ACM-hSOD1(G93A)) increases persistent sodium inward currents (PC(Na)), repetitive firing, and intracellular calcium transients, leading to specific motoneuron death days later. In contrast to TTX, which paradoxically increased twofold the amplitude of calcium transients and killed motoneurons, reduction of hyperexcitability by other specific (mexiletine) and nonspecific (spermidine and riluzole) blockers of voltage-sensitive sodium (Na(v)) channels restored basal calcium transients and prevented motoneuron death induced by ACM-hSOD1(G93A). These findings suggest that riluzole, the only FDA-approved drug with known benefits for ALS patients, acts by inhibiting hyperexcitability. Together, our data document that a critical element mediating the non-cell-autonomous toxicity of ACM-hSOD1(G93A) on motoneurons is increased excitability, an observation with direct implications for therapy of ALS. PMID:23486205

  7. Mutant SOD1-expressing astrocytes release toxic factors that trigger motoneuron death by inducing hyperexcitability

    PubMed Central

    Fritz, Elsa; Izaurieta, Pamela; Weiss, Alexandra; Mir, Franco R.; Rojas, Patricio; Gonzalez, David; Rojas, Fabiola; Brown, Robert H.; Madrid, Rodolfo

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a devastating paralytic disorder caused by dysfunction and degeneration of motoneurons starting in adulthood. Recent studies using cell or animal models document that astrocytes expressing disease-causing mutations of human superoxide dismutase 1 (hSOD1) contribute to the pathogenesis of ALS by releasing a neurotoxic factor(s). Neither the mechanism by which this neurotoxic factor induces motoneuron death nor its cellular site of action has been elucidated. Here we show that acute exposure of primary wild-type spinal cord cultures to conditioned medium derived from astrocytes expressing mutant SOD1 (ACM-hSOD1G93A) increases persistent sodium inward currents (PCNa), repetitive firing, and intracellular calcium transients, leading to specific motoneuron death days later. In contrast to TTX, which paradoxically increased twofold the amplitude of calcium transients and killed motoneurons, reduction of hyperexcitability by other specific (mexiletine) and nonspecific (spermidine and riluzole) blockers of voltage-sensitive sodium (Nav) channels restored basal calcium transients and prevented motoneuron death induced by ACM-hSOD1G93A. These findings suggest that riluzole, the only FDA-approved drug with known benefits for ALS patients, acts by inhibiting hyperexcitability. Together, our data document that a critical element mediating the non-cell-autonomous toxicity of ACM-hSOD1G93A on motoneurons is increased excitability, an observation with direct implications for therapy of ALS. PMID:23486205

  8. Drive latencies in hypoglossal motoneurons indicate developmental change in the brainstem respiratory network

    NASA Astrophysics Data System (ADS)

    Fietkiewicz, Christopher; Loparo, Kenneth A.; Wilson, Christopher G.

    2011-10-01

    The respiratory rhythm originates and diverges from the brainstem to drive thousands of motoneurons that are responsible for control of the diaphragm, intercostals and upper airway. These motoneurons are known to have a wide range of phase relationships, even within a single motoneuron pool. The proposed source of this rhythm, the preBötzinger complex (preBötC), responds to an array of developmental changes in the first days post-birth, specifically at postnatal day 3 (P3). We hypothesize that such developmental changes in the preBötC have a direct effect on motoneuron phase relationships and should be detectable around age P3. To test our hypothesis, we obtained single- and dual-voltage-clamp recordings of hypoglossal motoneurons in an in vitro slice preparation. We introduce a novel approach to analyzing the phase relationships between motoneurons by using cross-correlation analysis to determine the drive latencies. This analysis reveals that the distribution of drive latencies undergoes a significant change at or before age P3. We use a computational model of the in vitro slice to demonstrate the observed phase differences and hypothesize that network heterogeneity alone may not be sufficient to explain them. Through simulations, we show the effects on the preBötC of different network characteristics such as clustering and common inputs.

  9. Tonic inhibition and ponto-geniculo-occipital-related activities shape abducens motoneuron discharge during REM sleep

    PubMed Central

    Escudero, Miguel; Márquez-Ruiz, Javier

    2008-01-01

    Eye movements, ponto-geniculo-occipital (PGO) waves, muscular atonia and desynchronized cortical activity are the main characteristics of rapid eye movement (REM) sleep. Although eye movements designate this phase, little is known about the activity of the oculomotor system during REM sleep. In this work, we recorded binocular eye movements by the scleral search-coil technique and the activity of identified abducens (ABD) motoneurons along the sleep–wake cycle in behaving cats. The activity of ABD motoneurons during REM sleep was characterized by a tonic decrease of their mean firing rate throughout this period, and short bursts and pauses coinciding with the occurrence of PGO waves. We demonstrate that the decrease in the mean firing discharge was due to an active inhibition of ABD motoneurons, and that the occurrence of primary and secondary PGO waves induced a pattern of simultaneous but opposed phasic activation and inhibition on each ABD nucleus. With regard to eye movements, during REM sleep ABD motoneurons failed to codify eye position as during alertness, but continued to codify eye velocity. The pattern of tonic inhibition and the phasic activations and inhibitions shown by ABD motoneurons coincide with those reported in other non-oculomotor motoneurons, indicating that the oculomotor system – contrary to what has been accepted until now – is not different from other motor systems during REM sleep, and that all motor systems are receiving similar command signals during this period. PMID:18499728

  10. Activity dependent therapies modulate the spinal changes that motoneurons suffer after a peripheral nerve injury.

    PubMed

    Arbat-Plana, Ariadna; Torres-Espín, Abel; Navarro, Xavier; Udina, Esther

    2015-01-01

    Injury of a peripheral nerve not only leads to target denervation, but also induces massive stripping of spinal synapses on axotomized motoneurons, with disruption of spinal circuits. Even when regeneration is successful, unspecific reinnervation and the limited reconnection of the spinal circuits impair functional recovery. The aim of this study was to describe the changes that axotomized motoneurons suffer after peripheral nerve injury and how activity-dependent therapies and neurotrophic factors can modulate these events. We observed a marked decrease in glutamatergic synapses, with a maximum peak at two weeks post-axotomy, which was only partially reversed with time. This decrease was accompanied by an increase in gephyrin immunoreactivity and a disintegration of perineuronal nets (PNNs) surrounding the motoneurons. Direct application of neurotrophins at the proximal stump was not able to reverse these effects. In contrast, activity-dependent treatment, in the form of treadmill running, reduced the observed destructuring of perineuronal nets and the loss of glutamatergic synapses two weeks after injury. These changes were proportional to the intensity of the exercise protocol. Blockade of sensory inputs from the homolateral hindlimb also reduced PNN immunoreactivity around intact motoneurons, and in that case treadmill running did not reverse that loss, suggesting that the effects of exercise on motoneuron PNN depend on increased sensory activity. Preservation of motoneuron PNN and reduction of synaptic stripping by exercise could facilitate the maintenance of the spinal circuitry and benefit functional recovery after peripheral nerve injury. PMID:25448160

  11. Different discharge properties of facial nucleus motoneurons following neurotmesis in a rat model.

    PubMed

    Shi, Suming; Xu, Lei; Li, Jianfeng; Han, Yuechen; Wang, Haibo

    2016-08-26

    Facial nucleus motoneurons innervating the facial expressive muscles are involved in a wide range of motor activities, however, the types of movement related neurons and their electrophysiological transformation after peripheral facial nerve injury haven't been revealed. This study was designed to elucidate the types of facial nucleus motoneurons and their alterations of discharge parameters following peripheral facial nerve injury in vivo. Here we set up a rat model by implanting electrode arrays into the brainstem and recorded the electrophysiological signals of facial nucleus neurons in the intact rats for 5 days, then transected the trunk of facial nerve (TF), and continued the record for 4 weeks. At the 4th week post-surgery, the morphological changes of TFs were analyzed. In this paper, we described two types of putative facial nucleus motoneurons based on their electrophysiological properties and their firing frequency adaptation. Type I motoneurons (n=57.6%) were characterized by a sustained spike adaptation, Type II motoneurons (n=26.2%) were identified by a phasic fast spike firing. Facial palsy and synkinesia, caused by neurotmesis of TF, were accompanied by firing rates reduction and firing pattern alteration of motoneurons. Our findings suggest the presence of two types of facial nucleus motorneurons, and their response patterns after neurotmesis support the notion that the discharge pattern of motorneurons may play an important role in the facial nerve function. PMID:27423319

  12. Time course of human motoneuron recovery after sustained low-level voluntary activity.

    PubMed

    Héroux, Martin E; Butler, Annie A; Gandevia, Simon C; Taylor, Janet L; Butler, Jane E

    2016-02-01

    Motoneurons often fire repetitively and for long periods. In sustained voluntary contractions the excitability of motoneurons declines. We provide the first detailed description of the time course of human motoneuron recovery after sustained activity at a constant discharge rate. We recorded the discharge of single motor units (MUs, n = 30) with intramuscular wire electrodes inserted in triceps brachii during weak isometric contractions. Subjects (n = 15) discharged single MUs at a constant frequency (∼10 Hz) with visual feedback for prolonged durations (3-7 min) until rectified surface electromyogram (sEMG) of triceps brachii increased by ∼100%. After a rest of 1-2, 15, 30, 60, 120, or 240 s, subjects briefly resumed the contraction with the target MU at the same discharge rate. Each MU was tested with three to four rest periods. The magnitude of sEMG was increased when contractions were resumed, and the target motoneuron discharged at the test frequency following rest intervals of 2-60 s (P = 0.001-0.038). The increased sEMG indicates that greater excitatory drive was needed to discharge the motoneuron at the test rate. The increase in EMG recovered exponentially with a time constant of 28 s but did not return to baseline even after a rest period of ∼240 s. Thus the decline in motoneuron excitability from a weak contraction takes several minutes to recover fully. PMID:26609117

  13. Ankle and Other Signatures in Uhecr

    NASA Astrophysics Data System (ADS)

    Berezinsky, Veniamin

    2015-03-01

    The interaction signatures of UHE protons propagating through CMB are discussed. Much attention is given to ankle, which starting from 1963 is usually interpreted as a feature of transition from galactic to extragalactic cosmic rays. We argue here that this interpretation is now excluded. It gives more credit to alternative explanation of the ankle as an intrinsic part of the pair-production dip.

  14. Basketball injuries of the foot and ankle.

    PubMed

    McDermott, E P

    1993-04-01

    Foot and ankle injuries in basketball are discussed in three unrelated categories in this article. This includes a practical differential diagnosis of ankle sprains, acute conditions of the mid and hindfoot, overuse syndromes of nerve entrapment, fascial strain, synovitis, joint subluxation, and inflammation resulting from repetitive stress. The diagnosis and treatment of tendon inflammation of the extrinsic foot musculature is also reviewed. PMID:8097679

  15. Diagnosis and treatment of chronic ankle pain.

    PubMed

    Wukich, Dane K; Tuason, Dominick A

    2011-01-01

    The differential diagnosis for chronic ankle pain is quite broad. Ankle pain can be caused by intra-articular or extra-articular pathology and may be a result of a traumatic or nontraumatic event. A detailed patient history and physical examination, coupled with judicious selection of the appropriate imaging modalities, are vital in making an accurate diagnosis and providing effective treatment. Chronic ankle pain can affect all age groups, ranging from young athletes to elderly patients with degenerative joint and soft-tissue disorders. It has been estimated that 23,000 ankle sprains occur each day in the United States, representing approximately 1 sprain per 10,000 people per day. Because nearly one in five ankle injuries result in chronic symptoms, orthopaedic surgeons are likely to see patients with chronic ankle pain. Many patients with chronic ankle pain do not recall any history of trauma. Reviewing the management of the various disorders that can cause chronic ankle pain will help orthopaedic surgeons provide the best treatment for their patients. PMID:21553785

  16. Assessment of acute foot and ankle sprains.

    PubMed

    Lynam, Louise

    2006-07-01

    Acute ankle and foot trauma is a regular emergency presentation and prompt strategic assessment skills are required to enable nurses to categorise and prioritise these injuries appropriately. This article provides background information on the anatomy and physiology of the lower limb to help nurses to identify various grades of ankle sprain as well as injuries that are limb threatening PMID:16878848

  17. Redefining prosthetic ankle mechanics: non-anthropomorphic ankle design.

    PubMed

    LaPrè, Andrew K; Sup, Frank

    2013-06-01

    The moment transferred at the residual limb socket interface of transtibial amputees can be a limiting factor of the comfort and activity level of lower limb amputees. The high pressures seen can be a significant source of pain, as well as result in deep tissue damage. The compensation of the sound limbs causes an asymmetrical gait which can be a contributor of early onset osteoarthritis in the sound limbs. It has been shown that the moment transferred with conventional passive prostheses can be lowered in magnitude by aligning the tibia with ground reaction forces, but this limits the effectiveness of the device. With recent powered prosthetics designed to mimic the missing limb, power can be injected into the gait cycle, but can also be limited by this pressure threshold. This paper shows the results of calculations that suggest that altering the prosthetic ankle mechanism can reduce the socket interface moments by as much as 50%. This supports the development of an active non-anthropomorphic ankle prosthesis which reduces socket interface moments while still injecting substantial power levels into the gait cycle. PMID:24187257

  18. Synaptic Connectivity between Renshaw Cells and Motoneurons in the Recurrent Inhibitory Circuit of the Spinal Cord

    PubMed Central

    Moore, Niall J.; Bhumbra, Gardave S.; Foster, Joshua D.

    2015-01-01

    Renshaw cells represent a fundamental component of one of the first discovered neuronal circuits, but their function in motor control has not been established. They are the only central neurons that receive collateral projections from motor outputs, yet the efficacy of the excitatory synapses from single and converging motoneurons remains unknown. Here we present the results of dual whole-cell recordings from identified, synaptically connected Renshaw cell-motoneuron pairs in the mouse lumbar spinal cord. The responses from single Renshaw cells demonstrate that motoneuron synapses elicit large excitatory conductances with few or no failures. We show that the strong excitatory input from motoneurons results from a high probability of neurotransmitter release onto multiple postsynaptic contacts. Dual current-clamp recordings confirm that single motoneuron inputs were sufficient to depolarize the Renshaw cell beyond threshold for firing. Reciprocal connectivity was observed in approximately one-third of the paired recordings tested. Ventral root stimulation was used to evoke currents from Renshaw cells or motoneurons to characterize responses of single neurons to the activation of their corresponding presynaptic cell populations. Excitatory or inhibitory synaptic inputs in the recurrent inhibitory loop induced substantial effects on the excitability of respective postsynaptic cells. Quantal analysis estimates showed a large number of converging inputs from presynaptic motoneuron and Renshaw cell populations. The combination of considerable synaptic efficacy and extensive connectivity within the recurrent circuitry indicates a role of Renshaw cells in modulating motor outputs that may be considerably more important than has been previously supposed. SIGNIFICANCE STATEMENT We have recently shown that Renshaw cells mediate powerful shunt inhibition on motoneuron excitability. Here we complete a quantitative description of the recurrent circuit using recordings of

  19. Can Chronic Ankle Instability Be Prevented? Rethinking Management of Lateral Ankle Sprains

    PubMed Central

    Denegar, Craig R.; Miller, Sayers J.

    2002-01-01

    Objective: To pose the question, “Can chronic ankle instability be prevented?” The evaluation and treatment of chronic ankle instability is a significant challenge in athletic health care. The condition affects large numbers of athletes and is associated with reinjury and impaired performance. The management of acute injuries varies widely but in athletic training has traditionally focused on initial symptom management and rapid return to activity. A review of practice strategies and philosophies suggests that a more detailed evaluation of all joints affected by the injury, correction of hypomobility, and protection of healing structures may lead to a more optimal long-term outcome. Background: Sprains to the lateral ankle are common in athletes, and the reinjury rate is high. These injuries are often perceived as being isolated to the anterior talofibular and calcaneofibular ligaments. It is, however, becoming apparent that a lateral ankle sprain can injure other tissues and result in joint dysfunction throughout the ankle complex. Description: We begin by addressing the relationship between mechanical and functional instability. We then discuss normal ankle mechanics, sequelae to lateral ankle sprains, and abnormal ankle mechanics. Finally, tissue healing, joint dysfunction, and the management of acute lateral ankle sprain are reviewed, with an emphasis on restoring normal mechanics of the ankle-joint complex. A treatment model based on assessment of joint function, treatment of hypomobile segments, and protection of healing tissues at hypermobile segments is described. PMID:12937564

  20. The role of ankle bracing for prevention of ankle sprain injuries.

    PubMed

    Gross, Michael T; Liu, Hsin-Yi

    2003-10-01

    Lateral ankle sprains are one of the most common injuries incurred in recreational and competitive athletics. These injuries have a significant impact in terms of cost, athletic participation, and activities of daily living. Prophylactic ankle braces are often used to reduce the risk of injury recurrence when individuals return to athletic participation. The purpose of this clinical commentary is to review the literature and provide our own experience relative to the use of prophylactic ankle bracing. Relatively high incidence rates of ankle sprain injury have been reported for basketball and soccer athletes, military trainees, and individuals with a previous history of ankle sprain injury. Semirigid and laced ankle braces have significantly reduced the incidence of initial and recurrent ankle sprain injuries in athletic and military samples. With few exceptions, these braces do not appear to affect functional performance adversely. The prophylactic use of semirigid ankle braces appears warranted to reduce the incidence of initial and, in particular, recurrent ankle sprain injuries for individuals who participate in activities that have the highest risk for these injuries. Additional research is needed to evaluate the many new braces that are available and in use and their influence on the incidence of ankle sprain injury and functional performance. PMID:14620786

  1. Fatigue characteristics following ankle fractures.

    PubMed

    Behm, D G; St-Pierre, D M

    1997-09-01

    The purpose of the study was to examine the effects of surgical and nonsurgical treatment of previously immobilized ankle fractures on voluntary and evoked contractile properties before and following fatigue. Twelve control and 12 previously immobilized (4-14 wk postfracture) internally fixated and nonfixated ankles were investigated before and following an isometric, intermittent, submaximal, fatigue protocol of the plantar flexors. Before fatigue, fracture groups had significantly lower force output (42.7 vs 78.8 Nm) and muscle activation (78.3 vs 98.7%) than controls. Decreased activation may be attributed to the inhibitory effects of injured muscle and swelling. All groups had similar force and muscle activation decreases (7-10%) following fatigue; however, the internally fixated group performed significantly fewer contractions during the fatigue test (19) than the nonfixated (71) and controls (61). In contrast to the other groups, internally fixated subjects experienced increased (13%) rather than decreased EMG activity (controls: 10.9%, nonfixated: 21.1%). M-waves and twitch torques potentiated to a similar extent in the fracture groups (4.5 and 5.7%) but decreased significantly in the control group (24.2 and 9.8%). The similar fatigue durations of non-fixated subjects compared with controls may be attributed to a lack of impairment in nonfixated neuromuscular propagation and contractile kinetics, while the increased fatigability of fixated subjects with a similar lack of evoked contractile property impairments suggested a greater intrinsic fatigability. PMID:9309620

  2. Changes in electrophysiological properties of cat hypoglossal motoneurons during carbachol-induced motor inhibition.

    PubMed

    Fung, S J; Yamuy, J; Xi, M C; Engelhardt, J K; Morales, F R; Chase, M H

    2000-12-01

    The control of hypoglossal motoneurons during sleep is important from a basic science perspective as well as to understand the bases for pharyngeal occlusion which results in the obstructive sleep apnea syndrome. In the present work, we used intracellular recording techniques to determine changes in membrane properties in adult cats in which atonia was produced by the injection of carbachol into the pontine tegmentum (AS-carbachol). During AS-carbachol, 86% of the recorded hypoglossal motoneurons were found to be postsynaptically inhibited on the basis of analyses of their electrical properties; the electrical properties of the remaining 14% were similar to motoneurons recorded during control conditions. Those cells that exhibited changes in their electrical properties during AS-carbachol also displayed large-amplitude inhibitory synaptic potentials. Following sciatic nerve stimulation, hypoglossal motoneurons which responded with a depolarizing potential during control conditions exhibited a hyperpolarizing potential during AS-carbachol. Both spontaneous and evoked inhibitory potentials recorded during AS-carbachol were comparable to those that have been previously observed in trigeminal and spinal cord motoneurons under similar experimental conditions as well as during naturally occurring active sleep. Calculations based on modeling the changes that we found in input resistance and membrane time constant with a three-compartment neuron model suggest that shunts are present in all three compartments of the hypoglossal motoneuron model. Taken together, these data indicate that postsynaptic inhibitory drives are widely distributed on the soma-dendritic tree of hypoglossal motoneurons during AS-carbachol. These postsynaptic inhibitory actions are likely to be involved in the pathophysiology of obstructive sleep apnea. PMID:11102580

  3. Glutamate uptake block triggers deadly rhythmic bursting of neonatal rat hypoglossal motoneurons

    PubMed Central

    Sharifullina, Elina; Nistri, Andrea

    2006-01-01

    In the brain the extracellular concentration of glutamate is controlled by glial transporters that restrict the neurotransmitter action to synaptic sites and avoid excitotoxicity. Impaired transport of glutamate occurs in many cases of amyotrophic lateral sclerosis, a devastating motoneuron disease. Motoneurons of the brainstem nucleus hypoglossus are among the most vulnerable, giving early symptoms like slurred speech and dysphagia. However, the direct consequences of extracellular glutamate build-up, due to uptake block, on synaptic transmission and survival of hypoglossal motoneurons remain unclear and have been studied using the neonatal rat brainstem slice preparation as a model. Patch clamp recording from hypoglossal motoneurons showed that, in about one-third of these cells, inhibition of glutamate transport with the selective blocker dl-threo-β-benzyloxyaspartate (TBOA; 50 μ m) unexpectedly led to the emergence of rhythmic bursting consisting of inward currents of long duration with superimposed fast oscillations and synaptic events. Synaptic inhibition block facilitated bursting. Bursts had a reversal potential near 0 mV, and were blocked by tetrodotoxin, the gap junction blocker carbenoxolone, or antagonists of AMPA, NMDA or mGluR1 glutamate receptors. Intracellular Ca2+ imaging showed bursts as synchronous discharges among motoneurons. Synergy of activation of distinct classes of glutamate receptor plus gap junctions were therefore essential for bursting. Ablating the lateral reticular formation preserved bursting, suggesting independence from propagated network activity within the brainstem. TBOA significantly increased the number of dead motoneurons, an effect prevented by the same agents that suppressed bursting. Bursting thus represents a novel hallmark of motoneuron dysfunction triggered by glutamate uptake block. PMID:16455692

  4. Basic electrophysiological properties of spinal cord motoneurons during old age in the cat.

    PubMed

    Morales, F R; Boxer, P A; Fung, S J; Chase, M H

    1987-07-01

    1. The electrophysiological properties of alpha-motoneurons in old cats (14-15 yr) were compared with those of adult cats (1-3 yr). These properties were measured utilizing intracellular recording and stimulating techniques. 2. Unaltered in the old cat motoneurons were the membrane potential, action potential amplitude, and slopes of the initial segment (IS) and soma dendritic (SD) spikes, as well as the duration and amplitude of the action potential's afterhyperpolarization. 3. In contrast, the following changes in the electrophysiological properties of lumbar motoneurons were found in the old cats: a decrease in axonal conduction velocity, a shortening of the IS-SD delay, an increase in input resistance, and a decrease in rheobase. 4. In spite of these considerable changes in motoneuron properties in the old cat, normal correlations between different electrophysiological properties were maintained. The following key relationships, among others, were the same in adult and old cat motoneurons: membrane potential polarization versus action potential amplitude, duration of the afterhyperpolarization versus motor axon conduction velocity, and rheobase versus input conductance. 5. A review of the existing literature reveals that neither chronic spinal cord section nor deafferentation (13, 21) in adult animals produce the changes observed in old cats. Thus we consider it unlikely that a loss of synaptic contacts was responsible for the modifications in electrophysiological properties observed in old cat motoneurons. 6. We conclude that during old age there are significant changes in the soma-dendritic portion of cat motoneurons, as indicated by the modifications found in input resistance, rheobase, and IS-SD delay, as well as significant changes in their axons, as indicated by a decrease in conduction velocity. PMID:3612223

  5. Search the Foot and Ankle: Interactive Foot Diagram

    MedlinePlus

    ... Text Size Print Bookmark Search the Foot and Ankle Foot conditions in this region: Bunions (Hallux Valgus) » ... Injuries » Posterior Tibial Tendon Dysfunction (PTTD) » Tarsal Coalition » Ankle Fractures » Ankle Sprain » Chronic Ankle Instability » Equinus » Gout » ...

  6. How to Stretch Your Ankle After a Sprain

    MedlinePlus

    ... Decide If You Need to See an Orthopaedic Foot and Ankle Specialist How to Care for a Sprained Ankle How to Be Non- ... 10. Repeat 10 times. ​ Additional Resources How to Care for a Sprained Ankle How to Strengthen Your ... American Orthopaedic Foot & Ankle Society (AOFAS) offers information on this site ...

  7. The effect of osseous ankle configuration on chronic ankle instability

    PubMed Central

    Frigg, Arno; Magerkurth, Olaf; Valderrabano, Victor; Ledermann, Hans‐Peter; Hintermann, Beat

    2007-01-01

    Background Chronic ankle instability (CAI) is a common orthopaedic entity in sport. Although other risk factors have been studied extensively, little is known about how it is influenced by the osseous joint configuration. Aim To study the effect of osseous ankle configuration on CAI. Design Case–control study, level III. Setting Radiological examination with measurement of lateral x rays by an independent radiologist using a digital DICOM/PACS system. Patients A group of 52 patients who had had at least three recurrent sprains was compared with an age‐matched and sex‐matched control group of 52 healthy subjects. Main outcome measures The radius of the talar surface, the tibial coverage of the talus (tibiotalar sector) and the height of the talar body were measured. Results The talar radius was found to be larger in patients with CAI (21.2 (2.4) mm) than in controls (17.7 (1.9) mm; p<0.001, power >95%). The tibiotalar sector, representing the tibial coverage of the talus, was smaller in patients with CAI (80° (5.1°)) than in controls (88.4° (7.2°); p<0.001, power >95%). No significant difference was observed in the height of the talar body between patients with CAI (28.8 (2.6) mm) and controls (27.5 (4.0) mm; p = 0.055). Conclusion CAI is associated with an unstable osseous joint configuration characterised by a larger radius of the talus and a smaller tibiotalar sector. There is evidence that a higher talus might also play some part, particularly in women. PMID:17261556

  8. Charcot neuroarthropathy of the foot and ankle.

    PubMed

    Schon, L C; Easley, M E; Weinfeld, S B

    1998-04-01

    The goal of this study was to characterize Charcot neuroarthropathy of the foot and ankle by specific sites of involvement (ankle, hindfoot, midfoot, and forefoot), modes of presentation, methods of management, and outcome. A summary of treatment and results for 50 ankles, 22 hindfeet, 131 midfeet, and 18 forefeet is presented. Nondisplaced neuropathic ankle fractures typically healed uneventfully with casting and bracing. For displaced ankle fractures, closed reduction and casting generally resulted in loss of reduction and progressive deterioration; better results were obtained with open reduction and internal fixation, using supplemental Kirschner wires and screws. Ankles with Charcot neuroarthropathy and preexisting arthritis typically required arthrodesis. Of the ankles with neuropathic avascular talar necrosis, approximately 1/3 did well with nonoperative intervention and 2/3 required surgery. Chronic, unstable, malaligned Charcot ankles often required arthrodesis. Neuropathic calcaneal fractures were managed successfully nonoperatively. For feet with transverse tarsal joint involvement (Schon Type IV), management was more complex. Nonoperative treatment was successful for less than 1/2. Two thirds of the feet with midtarsus involvement (Schon Types I, II, and III) were managed successfully nonoperatively; 1/3 required surgery for recurrent ulceration, instability, or osteomyelitis. Half of the feet with forefoot neuroarthropathy required surgery for malalignment, ulceration, and/or difficulty with shoewear or braces. This review has established patterns of Charcot involvement of the foot and ankle with corresponding methods of treatment and subsequent responses. From this extensive clinical experience with 221 neuropathic fractures or Charcot joints, recommendations were derived to assist in selecting appropriate management options. PMID:9584374

  9. Conversion of ankle autofusion to total ankle replacement using the Salto XT revision prosthesis.

    PubMed

    Williamson, Emilie R C; Demetracopoulos, Constantine A; Ellis, Scott J

    2016-09-01

    Few reports in the literature have described the conversion of a surgically fused ankle to a total ankle replacement. The takedown of an autofusion and conversion to a prosthesis has not been described. We report the case of a patient with severe rheumatoid arthritis with an ankle autofusion fixed in equinus and severe talonavicular arthritis that was converted to ankle replacement using the Salto XT revision system. We describe the reasons why the decision was made to perform total ankle arthroplasty while concomitantly fusing the talonavicular joint, and discuss the rationale of the various surgical treatment options considered. We describe the clinical and radiographic outcomes achieved in this case. At 12 months post-operatively the patient reported significant reduction of pain, increased FAOS scores and had increased ankle range of motion. PMID:27502236

  10. Dependence of phrenic motoneurone output on the oscillatory component of arterial blood gas composition.

    PubMed Central

    Cross, B A; Grant, B J; Guz, A; Jones, P W; Semple, S J; Stidwill, R P

    1979-01-01

    1. The hypothesis that respiratory oscillations of arterial blood gas composition influence ventilation has been examined. 2. Phrenic motoneurone output recorded in the C5 root of the left phrenic nerve and the respiratory oscillations of arterial pH in the right common carotid artery were measured in vagotomized anaesthetized dogs which had been paralysed and artificially ventilated. 3. The effect of a change in tidal volume for one or two breaths on phrenic motoneurone output was measured with the inspiratory pump set at a constant frequency similar to, and in phase with, the animal's own respiratory frequency. A reduction of tidal volume to zero or an increase by 30% led to a corresponding change of mean carotid artery pH level. The changes of carotid artery pH resulted in a change of phrenic motoneurone output, predominantly of expiratory time (Te) but to a lesser extent of inspiratory time (T1) and also peak amplitude of 'integrated' phrenic motoneurone output (Phr). Denervation of the carotid bifurcation blocked this response. 4. The onset of movement of the inspiratory pump was triggered by the onset of phrenic motoneurone output. When a time delay was interposed between them, the phase relationship between respiratory oscillations of arterial pH and phrenic motoneurone output altered. The dominant effect was to alter Te; smaller and less consistent changes of Phr and T1 were observed. 5. When the inspiratory pump was maintained at a constant frequency but independent of and slightly different from the animal's own respiratory frequency (as judged by phrenic motoneurone output), the phase relationship between phrenic motoneurone output and the respiratory oscillations of pH changed breath by breath over a sequence of 100-200 breaths, without change of the mean level of arterial blood gas composition. Te varied by up to 30% about its mean value depending on the phase relationship. Ti and Phr were also dependent on the phase relationship but varied to a lesser

  11. Foot and Ankle Injuries in Runners.

    PubMed

    Tenforde, Adam S; Yin, Amy; Hunt, Kenneth J

    2016-02-01

    Foot and ankle injuries account for nearly one-third of running injuries. Achilles tendinopathy, plantar fasciopathy, and ankle sprains are 3 of the most common types of injuries sustained during training. Other common injuries include other tendinopathies of the foot and ankle, bone stress injuries, nerve conditions including neuromas, and joint disease including osteoarthritis. This review provides an evidence-based framework for the evaluation and optimal management of these conditions to ensure safe return to running participation and reduce risk for future injury. PMID:26616180

  12. Uncoupling nicotine mediated motoneuron axonal pathfinding errors and muscle degeneration in zebrafish

    SciTech Connect

    Welsh, Lillian; Tanguay, Robert L.; Svoboda, Kurt R.

    2009-05-15

    Zebrafish embryos offer a unique opportunity to investigate the mechanisms by which nicotine exposure impacts early vertebrate development. Embryos exposed to nicotine become functionally paralyzed by 42 hpf suggesting that the neuromuscular system is compromised in exposed embryos. We previously demonstrated that secondary spinal motoneurons in nicotine-exposed embryos were delayed in development and that their axons made pathfinding errors (Svoboda, K.R., Vijayaraghaven, S., Tanguay, R.L., 2002. Nicotinic receptors mediate changes in spinal motoneuron development and axonal pathfinding in embryonic zebrafish exposed to nicotine. J. Neurosci. 22, 10731-10741). In that study, we did not consider the potential role that altered skeletal muscle development caused by nicotine exposure could play in contributing to the errors in spinal motoneuron axon pathfinding. In this study, we show that an alteration in skeletal muscle development occurs in tandem with alterations in spinal motoneuron development upon exposure to nicotine. The alteration in the muscle involves the binding of nicotine to the muscle-specific AChRs. The nicotine-induced alteration in muscle development does not occur in the zebrafish mutant (sofa potato, [sop]), which lacks muscle-specific AChRs. Even though muscle development is unaffected by nicotine exposure in sop mutants, motoneuron axonal pathfinding errors still occur in these mutants, indicating a direct effect of nicotine exposure on nervous system development.

  13. The use of dendrograms to describe the electrical activity of motoneurons underlying behaviors in leeches

    PubMed Central

    Juárez-Hernández, León J.; Bisson, Giacomo; Torre, Vincent

    2013-01-01

    The present manuscript aims at identifying patterns of electrical activity recorded from neurons of the leech nervous system, characterizing specific behaviors. When leeches are at rest, the electrical activity of neurons and motoneurons is poorly correlated. When leeches move their head and/or tail, in contrast, action potential (AP) firing becomes highly correlated. When the head or tail suckers detach, specific patterns of electrical activity are detected. During elongation and contraction the electrical activity of motoneurons in the Medial Anterior and Dorsal Posterior nerves increase, respectively, and several motoneurons are activated both during elongation and contraction. During crawling, swimming, and pseudo-swimming patterns of electrical activity are better described by the dendrograms of cross-correlations of motoneurons pairs. Dendrograms obtained from different animals exhibiting the same behavior are similar and by averaging these dendrograms we obtained a template underlying a given behavior. By using this template, the corresponding behavior is reliably identified from the recorded electrical activity. The analysis of dendrograms during different leech behavior reveals the fine orchestration of motoneurons firing specific to each stereotyped behavior. Therefore, dendrograms capture the subtle changes in the correlation pattern of neuronal networks when they become involved in different tasks or functions. PMID:24098274

  14. Acute Stimulation of Transplanted Neurons Improves Motoneuron Survival, Axon Growth, and Muscle Reinnervation

    PubMed Central

    Grumbles, Robert M.; Liu, Yang; Thomas, Christie M.; Wood, Patrick M.

    2013-01-01

    Abstract Few options exist for treatment of pervasive motoneuron death after spinal cord injury or in neurodegenerative diseases such as amyotrophic lateral sclerosis. Local transplantation of embryonic motoneurons into an axotomized peripheral nerve is a promising approach to arrest the atrophy of denervated muscles; however, muscle reinnervation is limited by poor motoneuron survival. The aim of the present study was to test whether acute electrical stimulation of transplanted embryonic neurons promotes motoneuron survival, axon growth, and muscle reinnervation. The sciatic nerve of adult Fischer rats was transected to mimic the widespread denervation seen after disease or injury. Acutely dissociated rat embryonic ventral spinal cord cells were transplanted into the distal tibial nerve stump as a neuron source for muscle reinnervation. Immediately post-transplantation, the cells were stimulated at 20 Hz for 1 h. Other groups were used to control for the cell transplantation and stimulation. When neurons were stimulated acutely, there were significantly more neurons, including cholinergic neurons, 10 weeks after transplantation. This led to enhanced numbers of myelinated axons, reinnervation of more muscle fibers, and more medial and lateral gastrocnemius muscles were functionally connected to the transplant. Reinnervation reduced muscle atrophy significantly. These data support the concept that electrical stimulation rescues transplanted motoneurons and facilitates muscle reinnervation. PMID:23544978

  15. How shunting inhibition affects the discharge of lumbar motoneurones: a dynamic clamp study in anaesthetized cats

    PubMed Central

    Brizzi, L; Meunier, C; Zytnicki, D; Donnet, M; Hansel, D; d'Incamps, B Lamotte; van Vreeswijk, C

    2004-01-01

    In the present work, dynamic clamp was used to inject a current that mimicked tonic synaptic activity in the soma of cat lumbar motoneurones with a microelectrode. The reversal potential of this current could be set at the resting potential so as to prevent membrane depolarization or hyperpolarization. The only effect of the dynamic clamp was then to elicit a constant and calibrated increase of the motoneurone input conductance. The effect of the resulting shunt was investigated on repetitive discharges elicited by current pulses. Shunting inhibition reduced very substantially the firing frequency in the primary range without changing the slope of the current–frequency curves. The shift of the I–f curve was proportional to the conductance increase imposed by the dynamic clamp and depended on an intrinsic property of the motoneurone that we called the shunt potential. The shunt potential ranged between 11 and 37 mV above the resting potential, indicating that the sensitivity of motoneurones to shunting inhibition was quite variable. The shunt potential was always near or above the action potential voltage threshold. A theoretical model allowed us to interpret these experimental results. The shunt potential was shown to be a weighted time average of membrane voltage. The weighting factor is the phase response function of the neurone that peaks at the end of the interspike interval. The shunt potential indicates whether mixed synaptic inputs have an excitatory or inhibitory effect on the ongoing discharge of the motoneurone. PMID:15169842

  16. The tight relationship between asymmetric signaling and locational excitability in motoneuron dendrites

    PubMed Central

    Kim, Hojeong; Heckman, C J

    2015-01-01

    Spinal motoneurons possess large, highly branching dendritic structures that contain thousands of synaptic contacts and various voltage-gated ion channels (VGICs). Research has indicated that dendritic arborization and cable properties provide the basis for foundational dendritic processing, which is characterized by direction-dependent signal propagation and location-dependent channel activation in dendritic arbors. Due to these arbors' complex structure, signals attenuate differentially depending on whether propagation occurs from the soma to the dendrite or in the opposite direction. In addition, current thresholds for the activation of dendritic ion channels differ depending on the location of these channels within dendrites. However, whether and how these foundational properties for dendritic signaling and excitability are related in motoneurons remains unclear. Based on our analyses of anatomically reconstructed motoneurons and novel reduced models, we propose that 1) directional signal propagation is similar across spinal motoneurons, regardless of cell type-specific structures; 2) reduced models that retain dendritic signaling asymmetry can accurately replicate anatomical dendritic excitability in both passive and active modes; and 3) asymmetric signal propagation and locational dendritic excitability are closely related, irrespective of motoneurons' arbor structures. PMID:27066175

  17. Distinct Roles of Muscle and Motoneuron LRP4 in Neuromuscular Junction Formation

    PubMed Central

    Wu, Haitao; Lu, Yisheng; Shen, Chengyong; Patel, Neil; Gan, Lin; Xiong, Wen C.; Mei, Lin

    2012-01-01

    SUMMARY Neuromuscular junction (NMJ) formation requires precise interaction between motoneurons and muscle fibers. LRP4 is a receptor of agrin that is thought to act incis to stimulate MuSK in muscle fibers for postsynaptic differentiation. Here we dissected the roles of LRP4 in muscle fibers and motoneurons in NMJ formation by cell-specific mutation. Studies of muscle-specific mutants suggest that LRP4 is involved in deciding where to form AChR clusters in muscle fibers, postsynaptic differentiation, and axon terminal development. LRP4 in HEK293 cells increased synapsin or SV2 puncta in contacting axons of co-cultured neurons, suggesting a synaptogenic function. Analysis of LRP4 muscle and motoneuron double mutants and mechanistic studies suggest that NMJ formation may also be regulated by LRP4 in motoneurons, which could serve as agrin’s receptor in trans to induce AChR clusters. These observations uncovered distinct roles of LRP4 in motoneurons and muscles in NMJ development. PMID:22794264

  18. Distinct roles of muscle and motoneuron LRP4 in neuromuscular junction formation.

    PubMed

    Wu, Haitao; Lu, Yisheng; Shen, Chengyong; Patel, Neil; Gan, Lin; Xiong, Wen C; Mei, Lin

    2012-07-12

    Neuromuscular junction (NMJ) formation requires precise interaction between motoneurons and muscle fibers. LRP4 is a receptor of agrin that is thought to act in cis to stimulate MuSK in muscle fibers for postsynaptic differentiation. Here we dissected the roles of LRP4 in muscle fibers and motoneurons in NMJ formation by cell-specific mutation. Studies of muscle-specific mutants suggest that LRP4 is involved in deciding where to form AChR clusters in muscle fibers, postsynaptic differentiation, and axon terminal development. LRP4 in HEK293 cells increased synapsin or SV2 puncta in contacting axons of cocultured neurons, suggesting a synaptogenic function. Analysis of LRP4 muscle and motoneuron double mutants and mechanistic studies suggest that NMJ formation may also be regulated by LRP4 in motoneurons, which could serve as agrin's receptor in trans to induce AChR clusters. These observations uncovered distinct roles of LRP4 in motoneurons and muscles in NMJ development. PMID:22794264

  19. The tight relationship between asymmetric signaling and locational excitability in motoneuron dendrites.

    PubMed

    Kim, Hojeong; Heckman, C J

    2015-01-01

    Spinal motoneurons possess large, highly branching dendritic structures that contain thousands of synaptic contacts and various voltage-gated ion channels (VGICs). Research has indicated that dendritic arborization and cable properties provide the basis for foundational dendritic processing, which is characterized by direction-dependent signal propagation and location-dependent channel activation in dendritic arbors. Due to these arbors' complex structure, signals attenuate differentially depending on whether propagation occurs from the soma to the dendrite or in the opposite direction. In addition, current thresholds for the activation of dendritic ion channels differ depending on the location of these channels within dendrites. However, whether and how these foundational properties for dendritic signaling and excitability are related in motoneurons remains unclear. Based on our analyses of anatomically reconstructed motoneurons and novel reduced models, we propose that 1) directional signal propagation is similar across spinal motoneurons, regardless of cell type-specific structures; 2) reduced models that retain dendritic signaling asymmetry can accurately replicate anatomical dendritic excitability in both passive and active modes; and 3) asymmetric signal propagation and locational dendritic excitability are closely related, irrespective of motoneurons' arbor structures. PMID:27066175

  20. Motoneuron differentiation of induced pluripotent stem cells from SOD1G93A mice.

    PubMed

    Yao, Xiao-Li; Ye, Cheng-Hui; Liu, Qiang; Wan, Jian-bo; Zhen, Jun; Xiang, Andy Peng; Li, Wei-Qiang; Wang, Yitao; Su, Huangxing; Lu, Xi-Lin

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder mainly affecting motor neurons. Mutations in superoxide dismutase-1 (SOD-1) account for about 20% of familial ALS patients. A robust supply of motoneurons carrying the mutated gene would help understand the causes of motoneuron death and develop new therapeutics for the disease. Here, we established induced pluripotent stem (iPS) cell lines from SOD1G93A mice and compared their potency in motoneuron generation with normal iPS cells and mouse embryonic stem cells (E14). Our results showed that iPS cells derived from SOD1G93A mice possessed the similar potency in neuronal differentiation to normal iPS cells and E14 cells and can be efficiently driven to motoneuron-like phenotype. These cells exhibited typical neuronal morphology, expressed key motoneuron markers, including ChAT and HB9, and generated repetitive trains of action potentials. Furthermore, these neurons highly expressed human SOD-1 and exhibited shorter neurites compared to controls. The present study provides evidence that ALS-iPS cells can be used as disease models in high-throughput screening and mechanistic studies due to their ability to efficiently differentiate into specific neuronal subtypes. PMID:23724084

  1. Adenosine-mediated modulation of ventral horn interneurons and spinal motoneurons in neonatal mice.

    PubMed

    Witts, Emily C; Nascimento, Filipe; Miles, Gareth B

    2015-10-01

    Neuromodulation allows neural networks to adapt to varying environmental and biomechanical demands. Purinergic signaling is known to be an important modulatory system in many parts of the CNS, including motor control circuitry. We have recently shown that adenosine modulates the output of mammalian spinal locomotor control circuitry (Witts EC, Panetta KM, Miles GB. J Neurophysiol 107: 1925-1934, 2012). Here we investigated the cellular mechanisms underlying this adenosine-mediated modulation. Whole cell patch-clamp recordings were performed on ventral horn interneurons and motoneurons within in vitro mouse spinal cord slice preparations. We found that adenosine hyperpolarized interneurons and reduced the frequency and amplitude of synaptic inputs to interneurons. Both effects were blocked by the A1-type adenosine receptor antagonist DPCPX. Analysis of miniature postsynaptic currents recorded from interneurons revealed that adenosine reduced their frequency but not amplitude, suggesting that adenosine acts on presynaptic receptors to modulate synaptic transmission. In contrast to interneurons, recordings from motoneurons revealed an adenosine-mediated depolarization. The frequency and amplitude of synaptic inputs to motoneurons were again reduced by adenosine, but we saw no effect on miniature postsynaptic currents. Again these effects on motoneurons were blocked by DPCPX. Taken together, these results demonstrate differential effects of adenosine, acting via A1 receptors, in the mouse spinal cord. Adenosine has a general inhibitory action on ventral horn interneurons while potentially maintaining motoneuron excitability. This may allow for adaptation of the locomotor pattern generated by interneuronal networks while helping to ensure the maintenance of overall motor output. PMID:26311185

  2. Anesthetic isoflurane attenuates activated microglial cytokine-induced VSC4.1 motoneuronal apoptosis

    PubMed Central

    Yang, Shuangmei; Liu, Jun; Zhang, Xiaoran; Tian, Jianmin; Zuo, Zhichao; Liu, Jingjing; Yue, Xiuqin

    2016-01-01

    Isoflurane (ISO) exhibits neuroprotective effects against inflammation and apoptosis. However, the role of ISO in motoneuronal apoptosis induced by activated microglia remains poorly studied. We investigated the protective effects of ISO on the apoptosis of ventral spinal cord 4.1 (VSC4.1) motoneurons induced by lipopolysaccharide (LPS)-activated BV-2 microglia. Results indicated that ISO inhibited NF-κB activation and pro-inflammatory cytokine release in LPS-treated BV-2 microglia. Conditioned medium (CM) from activated BV-2 cells treated by ISO directly prevented VSC4.1 motoneurons from LPS-CM-induced neuronal apoptosis, as determined by the following: reductions in caspase-8, caspase-9, and caspase-3 activities; downregulation of pro-apoptotic procaspase-8, cleaved (cl)-caspase-8, procaspase-9, cl-caspase-9, caspase-3, cl-caspase-3, Bid, Bax, and cytochrome c expression; and upregulation of anti-apoptotic Bcl-2 expression in LPS-CM-cultured VSC4.1 motoneurons. Findings demonstrated that ISO inhibits BV-2 microglia activation and alleviates VSC4.1 motoneuronal apoptosis induced by microglial activation. These effects suggest that ISO can be used as an alternative agent for reducing neuronal apoptosis. PMID:27186270

  3. Alpha-7 and alpha-4 nicotinic receptor subunit immunoreactivity in genioglossus muscle motoneurons.

    PubMed

    Dehkordi, Ozra; Millis, Richard M; Dennis, Gary C; Coleman, Bernell R; Johnson, Sheree M; Changizi, Loubat; Ovid Trouth, C

    2005-02-15

    In the present study, immunohistochemistry combined with retrograde labeling techniques were used to determine if hypoglossal motoneurons (HMNs), retrogradely labeled after cholera toxin B subunit (CTB) injection to the genioglossus muscle in rats, show immunoreactivity for alpha-7 and alpha-4 subunits of nicotinic acetylcholine receptors (nAChRs). CTB-positive HMNs projecting to the genioglossus muscle were consistently labeled throughout the rostrocaudal extent of the hypoglossal nuclei with the greatest labeling at and caudal to area postrema. Alpha-7 subunit immunoreactivity was found in 39.44+/-5.10% of 870 CTB-labeled motoneurons and the alpha-4 subunit in 51.01+/-3.71% of 983 CTB-positive neurons. Rostrally, the number of genioglossal motoneurons demonstrating immunoreactivity for the alpha-7 subunit was 45.85+/-10.04% compared to 34.96+/-5.11% at and caudal to area postrema (P>0.1). The number of genioglossal motoneurons that showed immunoreactivity for the alpha-4 subunit was 55.03+/-4.83% at and caudal to area postrema compared to 42.98+/-3.90% in rostral areas (P=0.074). These results demonstrate that nAChR immunoreactivity is present in genioglossal motoneurons and suggest a role for alpha-7 and alpha-4 subunits containing nAChRs in the regulation of upper airway patency. PMID:15705531

  4. Multifunctional laryngeal motoneurons: an intracellular study in the cat.

    PubMed

    Shiba, K; Satoh, I; Kobayashi, N; Hayashi, F

    1999-04-01

    We studied the patterns of membrane potential changes in laryngeal motoneurons (LMs) during vocalization, coughing, swallowing, sneezing, and the aspiration reflex in decerebrate paralyzed cats. LMs, identified by antidromic activation from the recurrent laryngeal nerve, were expiratory (ELMs) or inspiratory (ILMs) cells that depolarized during their respective phases in eupnea. During vocalization, most ELMs depolarized and most ILMs hyperpolarized. Some ILMs depolarized slightly during vocalization. During coughing, ELMs depolarized abruptly at the transition from the inspiratory to the expiratory phase. In one-third of ELMs, this depolarization persisted throughout the abdominal burst. In the remainder ("type A"), it was interrupted by a transient repolarization. ILMs exhibited a membrane potential trajectory opposite to that of type A ELMs during coughing. During swallowing, the membrane potential of ELMs decreased transiently at the onset of the hypoglossal burst and then depolarized strongly during the burst. ILMs hyperpolarized sharply at the onset of the burst and depolarized as hypoglossal activity ceased. During sneezing, ELMs and ILMs exhibited membrane potential changes similar to those of type A ELMs and ILMs during coughing. During the aspiration reflex, ELMs and ILMs exhibited bell-shaped hyperpolarization and depolarization trajectories, respectively. We conclude that central drives to LMs, consisting of complex combinations of excitation and inhibition, vary during vocalization and upper airway defensive reflexes. This study provides data for analysis of the neuronal networks that produce these various behaviors and analysis of network reorganization caused by changes in dynamic connections between the respiratory and nonrespiratory neuronal networks. PMID:10087084

  5. Mild Hyperbaric Oxygen Improves Decreased Oxidative Capacity of Spinal Motoneurons Innervating the Soleus Muscle of Rats with Type 2 Diabetes.

    PubMed

    Takemura, Ai; Ishihara, Akihiko

    2016-09-01

    Rats with type 2 diabetes exhibit decreased oxidative capacity, such as reduced oxidative enzyme activity, low-intensity staining for oxidative enzymes in fibers, and no high-oxidative type IIA fibers, in the skeletal muscle, especially in the soleus muscle. In contrast, there are no data available concerning the oxidative capacity of spinal motoneurons innervating skeletal muscle of rats with type 2 diabetes. This study examined the oxidative capacity of motoneurons innervating the soleus muscle of non-obese rats with type 2 diabetes. In addition, this study examined the effects of mild hyperbaric oxygen at 1.25 atmospheres absolute with 36 % oxygen for 10 weeks on the oxidative capacity of motoneurons innervating the soleus muscle because mild hyperbaric oxygen improves the decreased oxidative capacity of the soleus muscle in non-obese rats with type 2 diabetes. Spinal motoneurons innervating the soleus muscle were identified using nuclear yellow, a retrograde fluorescent neuronal tracer. Thereafter, the cell body sizes and succinate dehydrogenase activity of identified motoneurons were analyzed. Decreased succinate dehydrogenase activity of small-sized alpha motoneurons innervating the soleus muscle was observed in rats with type 2 diabetes. The decreased succinate dehydrogenase activity of these motoneurons was improved by mild hyperbaric oxygen. Therefore, we concluded that rats with type 2 diabetes have decreased oxidative capacity in motoneurons innervating the soleus muscle and this decreased oxidative capacity is improved by mild hyperbaric oxygen. PMID:27220333

  6. Hox transcription factors influence motoneuron identity through the integrated actions of both homeodomain and non-homeodomain regions

    PubMed Central

    Misra, Mala; Sours, Emily; Lance-Jones, Cynthia

    2012-01-01

    Background Hox transcription factors play a critical role in the specification of motoneuron subtypes within the spinal cord. Our previous work showed that two orthologous members of this family, Hoxd10 and Hoxd11, exert opposing effects on motoneuron development in the lumbosacral (LS) spinal cord of the embryonic chick: Hoxd10 promotes the development of lateral motoneuron subtypes that project to dorsal limb muscles, while Hoxd11 represses the development of lateral subtypes in favor of medial subtypes that innervate ventral limb muscles and axial muscles. The striking degree of homology between the DNA-binding homeodomains of Hoxd10 and Hoxd11 suggested that non-homeodomain regions mediate their divergent effects. In the present study, we investigate the relative contributions of homeodomain and non-homeodomain regions of Hoxd10 and Hoxd11 to motoneuron specification. Results Using in ovo electroporation to express chimeric and mutant constructs in LS motoneurons, we find that both the homeodomain and non-homeodomain regions of Hoxd10 are necessary to specify lateral motoneurons. In contrast, non-homeodomain regions of Hoxd11 are sufficient to repress lateral motoneuron fates in favor of medial fates. Conclusions Together, our data demonstrate that even closely related Hox orthologues rely on distinct combinations of homeodomain-dependent and -independent mechanisms to specify motoneuron identity. PMID:22411553

  7. Motoneurons, DUM cells, and sensory neurons in an insect thoracic ganglion: a tracing study in the stick insect Carausius morosus.

    PubMed

    Goldammer, Jens; Büschges, Ansgar; Schmidt, Joachim

    2012-02-01

    Anatomical features of leg motoneurons, dorsal unpaired median (DUM) cells, and sensory neurons in stick insect mesothoracic ganglia were examined using fluorescent dye backfills of lateral nerves. Structures were analyzed in whole-mounts of ganglia and transverse sections. Numbers of motoneurons and details of their structure by far exceed previously published data. The general neuroanatomical layout of motoneurons matches the general orthopteran pattern. Cell bodies of excitatory motoneurons form clusters in the lateral cortex, dendrites branch mainly in the dorsal neuropil. We identified nine DUM cells, six of which have axons in nerve nl5. Most sensory fibers terminate in the ventral association center (VAC). Twenty-three small cell bodies located close to the soma of the fast extensor tibiae motoneuron likely belong to strand receptors. Labeled structures are compared with previously published data from stick insects and other orthopterous insects. PMID:21618233

  8. Lichen simplex chronicus on the ankle (image)

    MedlinePlus

    Lichen simplex chronicus on the ankle: Lichen simplex chronicus is also known as neurodermatitis. A minor itch may encourage scratching which increases the irritation, leading to more scratching. This ...

  9. Sports Injuries to the Foot and Ankle

    MedlinePlus

    ... Field Hockey Football Injuries Golf Injuries Lacrosse Rugby Running Soccer Softball Tennis Volleyball Find an ACFAS Physician ... Foot and Ankle Although golf does not involve running or jumping, injuries can occur to the foot ...

  10. Extended indications for foot and ankle arthroscopy.

    PubMed

    Hsu, Andrew R; Gross, Christopher E; Lee, Simon; Carreira, Dominic S

    2014-01-01

    Advances in foot and ankle arthroscopy have allowed surgeons to diagnose and treat a broadening array of disorders that were previously limited to open procedures. Arthroscopy of the posterior ankle, subtalar joint, and first metatarsophalangeal joint and tendoscopy can be used to address common foot and ankle ailments, with the potential benefits of decreased pain, fast recovery, and low complication rates. Posterior ankle and subtalar arthroscopy can be used to manage impingement, arthrofibrosis, synovitis, arthritis, fractures, and osteochondral defects. First metatarsophalangeal joint arthroscopy can address osteophytes, chronic synovitis, osteochondral defects, and degenerative joint disease. Tendoscopy is a minimally invasive alternative for evaluation and débridement of the Achilles, posterior tibial, flexor hallucis longus, and peroneal tendons. PMID:24382875

  11. American College of Foot and Ankle Surgeons

    MedlinePlus

    ... Programs Practice Management Practice Management Education Opportunities Practice Management e-Learning e-Learning CME Transcripts Corporate Relations Faculty Application Research & Publications Journal of Foot and Ankle Surgery ACFAS Update Read ...

  12. A novel dynamic ankle-supinating device.

    PubMed

    Gutierrez, Gregory M; Kaminski, Thomas

    2010-02-01

    Lateral ankle sprains (LAS) are among the most common joint injuries, and although most are resolved with conservative treatment, others develop chronic ankle instability (AI). Considerable attention has been directed toward understanding the underlying causes of this pathology; however, little is known concerning the neuromuscular mechanisms behind AI. A biomechanical analysis of the landing phase of a drop jump onto a device that simulates the mechanism of a LAS may give insight into the dynamic restraint mechanisms of the ankle by individuals with AI. Furthermore, work evaluating subjects who have a history of at least one lateral ankle sprain, yet did not develop AI, may help elucidate compensatory mechanisms following a LAS event. Identifying proper neuromuscular control strategies is crucial in reducing the incidence of AI. PMID:20147765

  13. Local axonal function of STAT3 rescues axon degeneration in the pmn model of motoneuron disease

    PubMed Central

    Selvaraj, Bhuvaneish Thangaraj; Frank, Nicolas; Bender, Florian L.P.; Asan, Esther

    2012-01-01

    Axonal maintenance, plasticity, and regeneration are influenced by signals from neighboring cells, in particular Schwann cells of the peripheral nervous system. Schwann cells produce neurotrophic factors, but the mechanisms by which ciliary neurotrophic factor (CNTF) and other neurotrophic molecules modify the axonal cytoskeleton are not well understood. In this paper, we show that activated signal transducer and activator of transcription-3 (STAT3), an intracellular mediator of the effects of CNTF and other neurotrophic cytokines, acts locally in axons of motoneurons to modify the tubulin cytoskeleton. Specifically, we show that activated STAT3 interacted with stathmin and inhibited its microtubule-destabilizing activity. Thus, ectopic CNTF-mediated activation of STAT3 restored axon elongation and maintenance in motoneurons from progressive motor neuronopathy mutant mice, a mouse model of motoneuron disease. This mechanism could also be relevant for other neurodegenerative diseases and provide a target for new therapies for axonal degeneration. PMID:23109669

  14. Neuroplasticity and Repair in Rodent Neurotoxic Models of Spinal Motoneuron Disease

    PubMed Central

    Gulino, Rosario

    2016-01-01

    Retrogradely transported toxins are widely used to set up protocols for selective lesioning of the nervous system. These methods could be collectively named “molecular neurosurgery” because they are able to destroy specific types of neurons by using targeted neurotoxins. Lectins such as ricin, volkensin, or modeccin and neuropeptide- or antibody-conjugated saporin represent the most effective toxins used for neuronal lesioning. Some of these specific neurotoxins could be used to induce selective depletion of spinal motoneurons. In this review, we extensively describe two rodent models of motoneuron degeneration induced by volkensin or cholera toxin-B saporin. In particular, we focus on the possible experimental use of these models to mimic neurodegenerative diseases, to dissect the molecular mechanisms of neuroplastic changes underlying the spontaneous functional recovery after motoneuron death, and finally to test different strategies of neural repair. The potential clinical applications of these approaches are also discussed. PMID:26862439

  15. Endoscopic Ankle Lateral Ligament Graft Anatomic Reconstruction.

    PubMed

    Michels, Frederick; Cordier, Guillaume; Guillo, Stéphane; Stockmans, Filip

    2016-09-01

    Chronic instability is a common complication of lateral ankle sprains. If nonoperative treatment fails, a surgical repair or reconstruction may be indicated. Today, endoscopic techniques to treat ankle instability are becoming more popular. This article describes an endoscopic technique, using a step-by-step approach, to reconstruct the ATFL and CFL with a gracilis graft. The endoscopic technique is reproducible and safe with regard to the surrounding anatomic structures. Short and midterm results confirm the benefits of this technique. PMID:27524711

  16. Non-Cell-Autonomous Regulation of Retrograde Motoneuronal Axonal Transport in an SBMA Mouse Model.

    PubMed

    Halievski, Katherine; Kemp, Michael Q; Breedlove, S Marc; Miller, Kyle E; Jordan, Cynthia L

    2016-01-01

    Defects in axonal transport are seen in motoneuronal diseases, but how that impairment comes about is not well understood. In spinal bulbar muscular atrophy (SBMA), a disorder linked to a CAG/polyglutamine repeat expansion in the androgen receptor (AR) gene, the disease-causing AR disrupts axonal transport by acting in both a cell-autonomous fashion in the motoneurons themselves, and in a non-cell-autonomous fashion in muscle. The non-cell-autonomous mechanism is suggested by data from a unique "myogenic" transgenic (TG) mouse model in which an AR transgene expressed exclusively in skeletal muscle fibers triggers an androgen-dependent SBMA phenotype, including defects in retrograde transport. However, motoneurons in this TG model retain the endogenous AR gene, leaving open the possibility that impairments in transport in this model also depend on ARs in the motoneurons themselves. To test whether non-cell-autonomous mechanisms alone can perturb retrograde transport, we generated male TG mice in which the endogenous AR allele has the testicular feminization mutation (Tfm) and, consequently, is nonfunctional. Males carrying the Tfm allele alone show no deficits in motor function or axonal transport, with or without testosterone treatment. However, when Tfm males carrying the myogenic transgene (Tfm/TG) are treated with testosterone, they develop impaired motor function and defects in retrograde transport, having fewer retrogradely labeled motoneurons and deficits in endosomal flux based on time-lapse video microscopy of living axons. These findings demonstrate that non-cell-autonomous disease mechanisms originating in muscle are sufficient to induce defects in retrograde transport in motoneurons. PMID:27517091

  17. Calcium dynamics and buffering in motoneurones of the mouse spinal cord.

    PubMed

    Palecek, J; Lips, M B; Keller, B U

    1999-10-15

    1. A quantitative analysis of endogenous calcium homeostasis was performed on 65 motoneurones in slices of the lumbar spinal cord from 2- to 8-day-old mice by simultaneous patch-clamp and microfluorometric calcium measurements. 2. Somatic calcium concentrations were monitored with a temporal resolution in the millisecond time domain. Measurements were performed by using a monochromator for excitation and a photomultiplier detection system. 3. Somatic calcium signalling was investigated during defined voltage-clamp protocols. Calcium responses were observed for membrane depolarizations positive to -50 mV. A linear relation between depolarization time and free calcium concentrations ([Ca2+]i) indicated that voltage-dependent calcium influx dominated the response. 4. Endogenous calcium homeostasis was quantified by using the 'added buffer' approach. In the presence of fura-2 and mag-fura-5, calcium transients decayed according to a monoexponential function. Decay-time constants showed a linear dependence on dye concentration and the extrapolated constant in the absence of indicator dye was 371 +/- 120 ms (n = 13 cells, 21 C). 5. For moderate elevations (< 1 microM), recovery kinetics of depolarization-induced calcium transients were characterized by a calcium-independent, 'effective' extrusion rate gamma = 140 +/- 47 s-1 (n = 13 cells, 21 C). 6. The endogenous calcium binding ratio for fixed buffers in spinal motoneurones was kappaB' = 50 +/- 17 (n = 13 cells), indicating that less than 2 % of cytosolic calcium ions contributed to [Ca2+]i. 7. Endogenous binding ratios in spinal motoneurones were small compared to those found in hippocampal or cerebellar Purkinje neurones. From a functional perspective, they provided motoneurones with rapid dynamics of cytosolic [Ca2+]i for a given set of influx, extrusion and uptake mechanisms. 8. With respect to pathophysiological conditions, our measurements are in agreement with a model where the selective vulnerability of spinal

  18. Neuroprotective Effects of Testosterone on Motoneuron and Muscle Morphology Following Spinal Cord Injury

    PubMed Central

    Byers, James S.; Huguenard, Anna L.; Kuruppu, Dulanji; Liu, Nai-Kui; Xu, Xiao-Ming; Sengelaub, Dale R.

    2014-01-01

    Treatment with testosterone is neuroprotective/neurotherapeutic after a variety of motoneuron injuries. Here we assessed whether testosterone might have similar beneficial effects after spinal cord injury (SCI). Young adult female rats received either sham or T9 spinal cord contusion injuries and were implanted with blank or testosterone-filled Silastic capsules. Four weeks later, motoneurons innervating the vastus lateralis muscle of the quadriceps were labeled with cholera toxin-conjugated horseradish peroxidase, and dendritic arbors were reconstructed in three dimensions. Soma volume, motoneuron number, lesion volume, and tissue sparing were also assessed, as were muscle weight, fiber cross-sectional area, and motor endplate size and density. Contusion injury resulted in large lesions, with no significant differences in lesion volume, percent total volume of lesion, or spared white or gray matter between SCI groups. SCI with or without testosterone treatment also had no effect on the number or soma volume of quadriceps motoneurons. However, SCI resulted in a decrease in dendritic length of quadriceps motoneurons in untreated animals, and this decrease was completely prevented by treatment with testosterone. Similarly, the vastus lateralis muscle weights and fiber cross-sectional areas of untreated SCI animals were smaller than those of sham-surgery controls, and these reductions were both prevented by testosterone treatment. No effects on motor endplate area or density were observed across treatment groups. These findings suggest that regressive changes in motoneuron and muscle morphology seen after SCI can be prevented by testosterone treatment, further supporting a role for testosterone as a neurotherapeutic agent in the injured nervous system. PMID:22314886

  19. Specificity in monosynaptic and disynaptic bulbospinal connections to thoracic motoneurones in the rat

    PubMed Central

    de Almeida, Anoushka T R; Kirkwood, Peter A

    2013-01-01

    The respiratory activity in the intercostal nerves of the rat is unusual, in that motoneurones of both branches of the intercostal nerves, internal and external, are activated during expiration. Here, the pathways involved in that activation were investigated in anaesthetised and in decerebrate rats by cross-correlation and by intracellular spike-triggered averaging from expiratory bulbospinal neurones (EBSNs), with a view to revealing specific connections that could be used in studies of experimental spinal cord injury. Decerebrate preparations, which showed the strongest expiratory activity, were found to be the most suitable for these measurements. Cross-correlations in these preparations showed monosynaptic connections from 16/19 (84%) of EBSNs, but only to internal intercostal nerve motoneurones (24/37, 65% of EBSN/nerve pairs), whereas disynaptic connections were seen for external intercostal nerve motoneurones (4/19, 21% of EBSNs or 7/25, 28% of EBSN/nerve pairs). There was evidence for additional disynaptic connections to internal intercostal nerve motoneurones. Intracellular spike-triggered averaging revealed excitatory postsynaptic potentials, which confirmed these connections. This is believed to be the first report of single descending fibres that participate in two different pathways to two different groups of motoneurones. It is of interest compared with the cat, where only one group of motoneurones is activated during expiration and only one of the pathways has been detected. The specificity of the connections could be valuable in studies of plasticity in pathological situations, but care will be needed in studying connections in such situations, because their strength was found here to be relatively weak. PMID:23774278

  20. Non-Cell-Autonomous Regulation of Retrograde Motoneuronal Axonal Transport in an SBMA Mouse Model

    PubMed Central

    Halievski, Katherine; Kemp, Michael Q.; Breedlove, S. Marc; Miller, Kyle E.

    2016-01-01

    Abstract Defects in axonal transport are seen in motoneuronal diseases, but how that impairment comes about is not well understood. In spinal bulbar muscular atrophy (SBMA), a disorder linked to a CAG/polyglutamine repeat expansion in the androgen receptor (AR) gene, the disease-causing AR disrupts axonal transport by acting in both a cell-autonomous fashion in the motoneurons themselves, and in a non-cell-autonomous fashion in muscle. The non-cell-autonomous mechanism is suggested by data from a unique “myogenic” transgenic (TG) mouse model in which an AR transgene expressed exclusively in skeletal muscle fibers triggers an androgen-dependent SBMA phenotype, including defects in retrograde transport. However, motoneurons in this TG model retain the endogenous AR gene, leaving open the possibility that impairments in transport in this model also depend on ARs in the motoneurons themselves. To test whether non-cell-autonomous mechanisms alone can perturb retrograde transport, we generated male TG mice in which the endogenous AR allele has the testicular feminization mutation (Tfm) and, consequently, is nonfunctional. Males carrying the Tfm allele alone show no deficits in motor function or axonal transport, with or without testosterone treatment. However, when Tfm males carrying the myogenic transgene (Tfm/TG) are treated with testosterone, they develop impaired motor function and defects in retrograde transport, having fewer retrogradely labeled motoneurons and deficits in endosomal flux based on time-lapse video microscopy of living axons. These findings demonstrate that non-cell-autonomous disease mechanisms originating in muscle are sufficient to induce defects in retrograde transport in motoneurons. PMID:27517091

  1. Complex ankle arthrodesis: Review of the literature

    PubMed Central

    Rabinovich, Remy V; Haleem, Amgad M; Rozbruch, S Robert

    2015-01-01

    Complex ankle arthrodesis is defined as an ankle fusion that is at high risk of delayed and nonunion secondary to patient comorbidities and/or local ankle/hindfoot factors. Risk factors that contribute to defining this group of patients can be divided into systemic factors and local factors pertaining to co-existing ankle or hindfoot pathology. Orthopaedic surgeons should be aware of these risk factors and their association with patients’ outcomes after complex ankle fusions. Both external and internal fixations have demonstrated positive outcomes with regards to achieving stable fixation and minimizing infection. Recent innovations in the application of biophysical agents and devices have shown promising results as adjuncts for healing. Both osteoconductive and osteoinductive agents have been effectively utilized as biological adjuncts for bone healing with low complication rates. Devices such as pulsed electromagnetic field bone stimulators, internal direct current stimulators and low-intensity pulsed ultrasound bone stimulators have been associated with faster bone healing and improved outcomes scores when compared with controls. The aim of this review article is to present a comprehensive approach to the management of complex ankle fusions, including the use of biophysical adjuncts for healing and a proposed algorithm for their treatment. PMID:26396936

  2. TOTAL ANKLE REPLACEMENT: WHY, WHEN AND HOW?

    PubMed Central

    Bonasia, Davide Edoardo; Dettoni, Federico; Femino, John E; Phisitkul, Phinit; Germano, Margherita; Amendola, Annunziato

    2010-01-01

    Total ankle replacement (TAR) was first attempted in the 1970s, but poor results led to its being considered inferior to ankle fusion until the late 1980s and early 1990s. By that time, newer designs which more closely replicated the natural anatomy of the ankle, showed improved clinical outcomes.1 Currently, even though controversy still exists about the effectiveness of TAR compared to ankle fusion, TAR has shown promising mid-term results and should no longer be considered an experimental procedure. Factors related to improved TAR outcomes include: 1) better patient selection, 2) more precise knowledge and replication of ankle biomechanics, 3) the introduction of less-constrained designs with reduced bone resection and no need for cementation, and 4) greater awareness of soft-tissue balance and component alignment. When TAR is performed, a thorough knowledge of ankle anatomy, pathologic anatomy and biomechanics is needed along with a careful pre-operative plan. These are fundamental in obtaining durable and predictable outcomes. The aim of this paper is to outline these aspects through a literature review. PMID:21045984

  3. Ankle flexibility and injury patterns in dancers.

    PubMed

    Wiesler, E R; Hunter, D M; Martin, D F; Curl, W W; Hoen, H

    1996-01-01

    Lower-extremity injuries are common among dancers and cause significant absences from rehearsals and performances. For this study of lower-extremity injuries in 101 ballet and 47 modern dance students, injuries requiring medical attention sustained over 1 academic year were associated with the following data obtained at the beginning of the school year: ankle flexibility, sex, dance discipline, previous injury, body mass index, and years of training. Eighty-three of the 148 students (age range, 12 to 28 years) reported prior lower-limb injuries, the most common being ankle sprains (28% of all dancers). Previous leg injuries correlated significantly with lower dorsiflexion measurements and with more new injuries. Female students had greater ankle and first metatarsophalangeal flexibility. Modern dancers had greater ankle inversion. Ninety-four students sustained 177 injuries during the study, including 75 sprains or strains and 71 cases of tendinitis. Thirty-nine percent (N = 69) were ankle injuries; 18% (N = 33) were knee injuries; 23% (N = 40) were foot injuries; and 20% (N = 35) were either hip or thigh injuries. Sixty-seven percent (N = 78) of the injured students were ballet dancers. Age, years of training, body mass index, sex, and ankle range of motion measurement had no predictive value for injury; previous injury and dance discipline both correlated with increased risk of injury. PMID:8947396

  4. Total ankle replacement for posttraumatic arthritis

    PubMed Central

    Weme, Rebecca A Nieuwe; van Solinge, Guido; N Doornberg, Job; Sierevelt, Inger; Haverkamp, Daniël; Doets, H Cornelis

    2015-01-01

    Background and purpose Most studies on total ankle replacement (TAR) have used a case mix of patients. We evaluated the outcome of TAR performed for end-stage arthritis either because of fracture or ligamentous injury. Patients and methods We prospectively followed 88 consecutive patients (50 postfracture ankles and 40 ankles with instability arthritis (2 bilateral)) who underwent TAR between 2001 and 2009. Mean follow-up for both groups was 5 years. Results Preoperative varus deformity of 10° or more was present in 23 ankles in the instability group. At 6 years, survival with revision or salvage fusion as an endpoint was 87% (95% CI: 74–99) in the postfracture group and 79% (95% CI: 63–94) in the instability group. Progressive periprosthetic osteolysis was seen in 23 ankles, and required salvage fusion in 6. The number of reoperations was similar in both groups. Clinical outcome, as assessed with 2 ankle scores and 2 questionnaires, showed good results and was similar at the latest follow-up. Interpretation The outcome was similar in the postfracture and instability groups and also similar to that reported in series including a case mix of patients. In contrast to earlier reports, preoperative frontal plane deformity in this series was not identified as a risk factor for failure. PMID:25772269

  5. Tremor in Parkinson's disease patients can be induced by uncontrolled activation and uninhibited synchronization of alpha2-motoneuron firing to which alpha1-motoneuron firing synchronizes.

    PubMed

    Schalow, Giselher

    2005-12-01

    With the surface electromyography (sEMG) and the single nerve-fibre action potential recording method a mechanism is measured how rhythmic muscle contraction and tremor in Parkinson's disease patients is generated. With sEMG it could be shown that the tremor started when alpha2-motor units (FR-type) spontaneously began to fire synchronizedly oscillatory. Two possibilities of alpha2-motor unit synchronization were observed. In one case one alpha2-motor unit started to fire oscillatory and other alpha2-motor units started to fire oscillatory in synchronization with the first alpha2-motor unit. In a second case several alpha2-motor units fired oscillatory, but not in a synchronized manner. With the synchronization of the oscillatory firing alpha2-motor units again synchronizedly oscillatory firing of several alpha2-motor units appeared. When later on, several additional alpha1-motor units (FF-type) started to fire and in synchrony with the synchronizedly oscillatory firing alpha2-motor units (FR-type), rhythmic muscle contraction and tremor were observed. Visible muscle contraction and tremor stopped, when the alpha1-motor units stopped firing, which could a.o. be achieved by the patient concentrating on the tremor. The single nerve-fibre action potential recording method showed that alpha1 and alpha2-motoneurons in the cauda equine nerve roots fired oscillatory, that they could synchronize their firing and that these oscillatory firing motoneurons could build up an external loop to the periphery in the way that gamma-motoneurons and muscle spindle afferents were included in the rhythmic coordinated firing But the synchronization of oscillatory firing was only transient and the building up of an external loop to the periphery only occurred in non-Parkinson patients upon strong repetitive reflex stimulation. It is therefore concluded that in patients with Parkinson's disease there is firstly a lack of inhibition, so that motoneurons can start to fire oscillatory upon

  6. Mechanisms of spinal motoneurons survival in rats under simulated hypogravity on earth

    NASA Astrophysics Data System (ADS)

    Islamov, R. R.; Mishagina, E. A.; Tyapkina, O. V.; Shajmardanova, G. F.; Eremeev, A. A.; Kozlovskaya, I. B.; Nikolskij, E. E.; Grigorjev, A. I.

    2011-05-01

    It was previously shown that different cell types in vivo and in vitro may die via apoptosis under weightlessness conditions in space as well as in simulated hypogravity on the Earth. We assessed survivability of spinal motoneurons of rats after 35-day antiorthostatic hind limb suspension. Following weight bearing, unloading the total protein content in lumbar spinal cord is dropped by 21%. The electrophysiological studies of m. gastrocnemius revealed an elevated motoneurons' reflex excitability and conduction disturbances in the sciatic nerve axons. The number of myelinated fibers in the ventral root of experimental animals was insignificantly increased by 35-day of antiorthostatic hind limb suspension, although the retrograde axonal transport was significantly decreased during the first week of simulated hypogravity. The results of the immunohistochemical assay with antibodies against proapoptotic protein caspase 9 and cytotoxicity marker neuron specific nitric oxide synthase (nNOS) and the TUNEL staining did not reveal any signs of apoptosis in motoneurons of suspended and control animals. To examine the possible adaptation mechanisms activated in motoneurons in response to simulated hypogravity we investigated immunoexpression of Hsp25 and Hsp70 in lumbar spinal cord of the rats after 35-day antiorthostatic hind limb suspension. Comparative analysis of the immunohistochemical reaction with anti-Hsp25 antibodies revealed differential staining of motoneurons in intact and experimental animals. The density of immunoprecipitate with anti-Hsp25 antibodies was substantially higher in motoneurons of the 35-day suspended than control rats and the more intensive precipitate in this reaction was observed in motoneuron neuritis. Quantitative analysis of Hsp25 expression demonstrated an increase in the Hsp25 level by 95% in experimental rats compared to the control. The immunoexpression of Hsp70 found no qualitative and quantitative differences in control and experimental

  7. Relations among passive electrical properties of lumbar alpha-motoneurones of the cat.

    PubMed Central

    Gustafsson, B; Pinter, M J

    1984-01-01

    The relations among passive membrane properties have been examined in cat motoneurones utilizing exclusively electrophysiological techniques. A significant relation was found to exist between the input resistance and the membrane time constant. The estimated electrotonic length showed no evident tendency to vary with input resistance but did show a tendency to decrease with increasing time constant. Detailed analysis of this trend suggests, however, that a variation in dendritic geometry is likely to exist among cat motoneurones, such that the dendritic trees of motoneurones projecting to fast-twitch muscle units are relatively more expansive than those of motoneurones projecting to slow-twitch units. Utilizing an expression derived from the Rall neurone model, the total capacitance of the equivalent cylinder corresponding to a motoneurone has been estimated. With the assumption of a constant and uniform specific capacitance of 1 mu F/cm2, the resulting values have been used as estimates of cell surface area. These estimates agree well with morphologically obtained measurements from cat motoneurones reported by others. Both membrane time constant (and thus likely specific membrane resistivity) and electrotonic length showed little tendency to vary with surface area. However, after-hyperpolarization (a.h.p.) duration showed some tendency to vary such that cells with brief a.h.p. duration were, on average, larger than those with longer a.h.p. durations. Apart from motoneurones with the lowest values, axonal conduction velocity was only weakly related to variations in estimated surface area. Input resistance and membrane time constant were found to vary systematically with the a.h.p. duration. Analysis suggested that the major part of the increase in input resistance with a.h.p. duration was related to an increase in membrane resistivity and a variation in dendritic geometry rather than to differences in surface area among the motoneurones. The possible effects of

  8. Cat hindlimb motoneurons during locomotion. I. Destination, axonal conduction velocity, and recruitment threshold.

    PubMed

    Hoffer, J A; Loeb, G E; Marks, W B; O'Donovan, M J; Pratt, C A; Sugano, N

    1987-02-01

    Fine flexible wire microelectrodes chronically implanted in the fifth lumbar ventral root (L5 VR) of 17 cats rendered stable records of the natural discharge patterns of 164 individual axons during locomotion on a treadmill. Fifty-one out of 164 axons were identified as motoneurons projecting to the anterior thigh muscle group. For these axons, the centrifugal propagation of action potentials was demonstrated by the technique of spike-triggered averaging using signals recorded from cuff electrodes implanted around the femoral nerve. The axonal conduction velocity was measured from the femoral nerve cuff records. For 43/51 motoneurons, the corresponding target muscle was identified by spike-triggered averaging of signals recorded from bipolar EMG electrodes implanted in each of the anterior thigh muscles: vastus intermedius, medialis and lateralis, sartorius anterior and medialis, and rectus femoris. For 32/51 motoneurons, the recruitment threshold during locomotion was determined from the mean value of the rectified digitally smoothed EMG of the target muscle measured at the time when the motoneuron fired its first spike for each step. The recruitment threshold of every motoneuron was relatively constant for a given speed of walking, but for some units there were small systematic variations as a function of treadmill speed (range: 0.1-1.3 m/s). Recruitment thresholds were standardized with respect to the mean value of peak EMG activity of the target muscle during 16 s of walking at 0.5 m/s. For 28/51 motoneurons recorded in nine cats, recruitment thresholds (range: 3-93% of peak target muscle EMG) were linearly correlated (r = 0.51, P less than 0.02) to axonal conduction velocities (range: 57-117 m/s). In addition, for seven recorded pairs of motoneurons that projected to the same muscle in the same cat, the recruitment thresholds were ordered by relative conduction velocities. Taken together, these results are consistent with the notion that, in normal cat

  9. Do Ankle Orthoses Improve Ankle Proprioceptive Thresholds or Unipedal Balance in Older Persons with Peripheral Neuropathy?

    PubMed Central

    Son, Jaebum; Ashton-Miller, James A.; Richardson, James K.

    2010-01-01

    Objective To determine whether ankle orthoses that provide medial and lateral support, and have been found to decrease gait variability in older persons with peripheral neuropathy, decrease (improve) frontal plane ankle proprioceptive thresholds or increase unipedal stance time in that same population. Design Observational study in which unipedal stance time was determined with a stopwatch, and frontal plane ankle (inversion and eversion) proprioceptive thresholds were quantified during bipedal stance with and without the ankle orthoses, in 11 older diabetic subjects with peripheral neuropathy (8 men; age 72 ± 7.1 years) using a foot cradle system which presented a series of 100 rotational stimuli. Results The subjects demonstrated no change in combined frontal plane (inversion + eversion) proprioceptive thresholds or unipedal stance time with versus without the orthoses (1.06 ± 0.56 versus 1.13 ± 0.39 degrees, respectively; p = 0.955 and 6.1 ± 6.5 versus 6.2 ± 5.4 seconds, respectively; p = 0.922). Conclusion Ankle orthoses which provide medial-lateral support do not appear to change ankle inversion/eversion proprioceptive thresholds or unipedal stance time in older persons with diabetic peripheral neuropathy. Previously identified improvements in gait variability using orthoses in this population are therefore likely related to an orthotically-induced stiffening of the ankle rather than a change in ankle afferent function. PMID:20407302

  10. Mechanics of slope walking in the cat: quantification of muscle load, length change, and ankle extensor EMG patterns.

    PubMed

    Gregor, Robert J; Smith, D Webb; Prilutsky, Boris I

    2006-03-01

    Unexpected changes in flexor-extensor muscle activation synergies during slope walking in the cat have been explained previously by 1) a reorganization of circuitry in the central pattern generator or 2) altered muscle and cutaneous afferent inputs to motoneurons that modulate their activity. The aim of this study was to quantify muscle length changes, muscle loads, and ground reaction forces during downslope, level, and upslope walking in the cat. These mechanical variables are related to feedback from muscle length and force, and paw pad cutaneous afferents, and differences in these variables between the slope walking conditions could provide additional insight into possible mechanisms of the muscle control. Kinematics, ground reaction forces, and EMG were recorded while cats walked on a walkway in three conditions: downslope (-26.6 deg), level (0 deg), and upslope (26.6 deg). The resultant joint moments were calculated using inverse dynamics analysis; length and velocity of major hindlimb muscle-tendon units (MTUs) were calculated using a geometric model and calculated joint angles. It was found that during stance in downslope walking, the MTU stretch of ankle and knee extensors and MTU peak stretch velocities of ankle extensors were significantly greater than those in level or upslope conditions, whereas forces applied to the paw pad and peaks of ankle and hip extensor moments were significantly smaller. The opposite was true for upslope walking. It was suggested that these differences between upslope and downslope walking might affect motion-dependent feedback, resulting in muscle activity changes recorded here or reported in the literature. PMID:16207777

  11. Control of hypoglossal motoneurones during naturally occurring sleep and wakefulness in the intact, unanaesthetized cat: a field potential study.

    PubMed

    Fung, Simon J; Chase, Michael H

    2014-08-01

    The present electrophysiological study was designed to determine the discharge threshold of hypoglossal motoneurones during naturally occurring states of sleep and wakefulness in the intact, unanaesthetized cat. The antidromic field potential, which reflects the net level of membrane excitability of motoneurones and therefore their discharge threshold, was recorded in the hypoglossal nucleus following stimulation of the hypoglossal nerve. The amplitude of the antidromic field potential was larger during wakefulness and non-rapid eye movement (NREM) sleep compared with REM sleep. There was no significant difference in the amplitude of the field potential when wakefulness was compared with NREM sleep (P = 0.103, df = 3, t = 2.324). However, there was a 46% reduction in amplitude during REM sleep compared with NREM sleep (P < 0.001, df = 10, t = 6.421) or wakefulness (P < 0.01, df = 4, t = -4.598). These findings indicate that whereas the excitability of motoneurones that comprise the hypoglossal motor pool is relatively constant during wakefulness and NREM sleep, their excitability is significantly reduced during REM sleep. This state-dependent pattern of control of hypoglossal motoneurones during REM sleep is similar to that reported for motoneurones in other motor nuclei at all levels of the neuraxis. The decrease in the evoked response of hypoglossal motoneurones, which reflects a significant increase in the discharge threshold of individual motoneurones, results in atonia of the lingual and related muscles during REM sleep. PMID:24605864

  12. Paratrooper's Ankle Fracture: Posterior Malleolar Fracture

    PubMed Central

    Young, Ki Won; Cho, Jae Ho; Kim, Hyung Seuk; Cho, Hun Ki; Lee, Kyung Tai

    2015-01-01

    Background We assessed the frequency and types of ankle fractures that frequently occur during parachute landings of special operation unit personnel and analyzed the causes. Methods Fifty-six members of the special force brigade of the military who had sustained ankle fractures during parachute landings between January 2005 and April 2010 were retrospectively analyzed. The injury sites and fracture sites were identified and the fracture types were categorized by the Lauge-Hansen and Weber classifications. Follow-up surveys were performed with respect to the American Orthopedic Foot and Ankle Society ankle-hindfoot score, patient satisfaction, and return to preinjury activity. Results The patients were all males with a mean age of 23.6 years. There were 28 right and 28 left ankle fractures. Twenty-two patients had simple fractures and 34 patients had comminuted fractures. The average number of injury and fractures sites per person was 2.07 (116 injuries including a syndesmosis injury and a deltoid injury) and 1.75 (98 fracture sites), respectively. Twenty-three cases (41.07%) were accompanied by posterior malleolar fractures. Fifty-five patients underwent surgery; of these, 30 had plate internal fixations. Weber type A, B, and C fractures were found in 4, 38, and 14 cases, respectively. Based on the Lauge-Hansen classification, supination-external rotation injuries were found in 20 cases, supination-adduction injuries in 22 cases, pronation-external rotation injuries in 11 cases, tibiofibular fractures in 2 cases, and simple medial malleolar fractures in 2 cases. The mean follow-up period was 23.8 months, and the average follow-up American Orthopedic Foot and Ankle Society ankle-hindfoot score was 85.42. Forty-five patients (80.36%) reported excellent or good satisfaction with the outcome. Conclusions Posterior malleolar fractures occurred in 41.07% of ankle fractures sustained in parachute landings. Because most of the ankle fractures in parachute injuries were

  13. Functional Expression of T-Type Ca2+ Channels in Spinal Motoneurons of the Adult Turtle

    PubMed Central

    Canto-Bustos, Martha; Loeza-Alcocer, Emanuel; González-Ramírez, Ricardo; Gandini, María A.; Delgado-Lezama, Rodolfo; Felix, Ricardo

    2014-01-01

    Voltage-gated Ca2+ (CaV) channels are transmembrane proteins comprising three subfamilies named CaV1, CaV2 and CaV3. The CaV3 channel subfamily groups the low-voltage activated Ca2+ channels (LVA or T-type) a significant role in regulating neuronal excitability. CaV3 channel activity may lead to the generation of complex patterns of action potential firing such as the postinhibitory rebound (PIR). In the adult spinal cord, these channels have been found in dorsal horn interneurons where they control physiological events near the resting potential and participate in determining excitability. In motoneurons, CaV3 channels have been found during development, but their functional expression has not yet been reported in adult animals. Here, we show evidence for the presence of CaV3 channel-mediated PIR in motoneurons of the adult turtle spinal cord. Our results indicate that Ni2+ and NNC55-0396, two antagonists of CaV3 channel activity, inhibited PIR in the adult turtle spinal cord. Molecular biology and biochemical assays revealed the expression of the CaV3.1 channel isotype and its localization in motoneurons. Together, these results provide evidence for the expression of CaV3.1 channels in the spinal cord of adult animals and show also that these channels may contribute to determine the excitability of motoneurons. PMID:25255145

  14. Extrasynaptic α6 Subunit-Containing GABAA Receptors Modulate Excitability in Turtle Spinal Motoneurons

    PubMed Central

    Andres, Carmen; Aguilar, Justo; González-Ramírez, Ricardo; Elias-Viñas, David; Felix, Ricardo; Delgado-Lezama, Rodolfo

    2014-01-01

    Motoneurons are furnished with a vast repertoire of ionotropic and metabotropic receptors as well as ion channels responsible for maintaining the resting membrane potential and involved in the regulation of the mechanisms underlying its membrane excitability and firing properties. Among them, the GABAA receptors, which respond to GABA binding by allowing the flow of Cl− ions across the membrane, mediate two distinct forms of inhibition in the mature nervous system, phasic and tonic, upon activation of synaptic or extrasynaptic receptors, respectively. In a previous work we showed that furosemide facilitates the monosynaptic reflex without affecting the dorsal root potential. Our data also revealed a tonic inhibition mediated by GABAA receptors activated in motoneurons by ambient GABA. These data suggested that the high affinity GABAA extrasynaptic receptors may have an important role in motor control, though the molecular nature of these receptors was not determined. By combining electrophysiological, immunofluorescence and molecular biology techniques with pharmacological tools here we show that GABAA receptors containing the α6 subunit are expressed in adult turtle spinal motoneurons and can function as extrasynaptic receptors responsible for tonic inhibition. These results expand our understanding of the role of GABAA receptors in motoneuron tonic inhibition. PMID:25531288

  15. Localization of pectoral fin motoneurons (sonic and hovering) in the croaking gourami Trichopsis vittatus.

    PubMed

    Ladich, F; Fine, M L

    1992-01-01

    The pectoral fin of the croaking gourami, Trichopsis vittatus, has become modified as a sound-producing organ and retains its original function in locomotion and hovering. We used retrograde transport of horseradish peroxidase to localize sonic motoneurons in Trichopsis. Betta splendens, a related nonsonic gourami with unspecialized pectoral fins, served as a control. A single injection into Trichopsis epaxial muscle labeled a dorsal motor column of large cells (mean of 16.3 microns) ventrolateral to the central canal. Pectoral motoneurons formed a ventrolateral spinal motor column of smaller neurons (means from 7.7 to 11.9 microns, depending upon fish size), of about 2 mm in rostrocaudal extent, starting in the caudal medulla. Our data suggest that motoneurons for different pectoral muscles are segregated into rostrocaudal pools within the column. Distribution, morphology and size of motoneurons were similar between Trichopsis and Betta, and there was no evidence of a distinct population of neurons which might be specialized exclusively for sound production. These data suggest that a fish can evolve a specialized end organ without major reorganization of the central nervous system. PMID:1537046

  16. Extrasynaptic α6 subunit-containing GABAA receptors modulate excitability in turtle spinal motoneurons.

    PubMed

    Andres, Carmen; Aguilar, Justo; González-Ramírez, Ricardo; Elias-Viñas, David; Felix, Ricardo; Delgado-Lezama, Rodolfo

    2014-01-01

    Motoneurons are furnished with a vast repertoire of ionotropic and metabotropic receptors as well as ion channels responsible for maintaining the resting membrane potential and involved in the regulation of the mechanisms underlying its membrane excitability and firing properties. Among them, the GABAA receptors, which respond to GABA binding by allowing the flow of Cl- ions across the membrane, mediate two distinct forms of inhibition in the mature nervous system, phasic and tonic, upon activation of synaptic or extrasynaptic receptors, respectively. In a previous work we showed that furosemide facilitates the monosynaptic reflex without affecting the dorsal root potential. Our data also revealed a tonic inhibition mediated by GABAA receptors activated in motoneurons by ambient GABA. These data suggested that the high affinity GABAA extrasynaptic receptors may have an important role in motor control, though the molecular nature of these receptors was not determined. By combining electrophysiological, immunofluorescence and molecular biology techniques with pharmacological tools here we show that GABAA receptors containing the α6 subunit are expressed in adult turtle spinal motoneurons and can function as extrasynaptic receptors responsible for tonic inhibition. These results expand our understanding of the role of GABAA receptors in motoneuron tonic inhibition. PMID:25531288

  17. Sensitization of neonatal rat lumbar motoneuron by the inflammatory pain mediator bradykinin

    PubMed Central

    Bouhadfane, Mouloud; Kaszás, Attila; Rózsa, Balázs; Harris-Warrick, Ronald M; Vinay, Laurent; Brocard, Frédéric

    2015-01-01

    Bradykinin (Bk) is a potent inflammatory mediator that causes hyperalgesia. The action of Bk on the sensory system is well documented but its effects on motoneurons, the final pathway of the motor system, are unknown. By a combination of patch-clamp recordings and two-photon calcium imaging, we found that Bk strongly sensitizes spinal motoneurons. Sensitization was characterized by an increased ability to generate self-sustained spiking in response to excitatory inputs. Our pharmacological study described a dual ionic mechanism to sensitize motoneurons, including inhibition of a barium-sensitive resting K+ conductance and activation of a nonselective cationic conductance primarily mediated by Na+. Examination of the upstream signaling pathways provided evidence for postsynaptic activation of B2 receptors, G protein activation of phospholipase C, InsP3 synthesis, and calmodulin activation. This study questions the influence of motoneurons in the assessment of hyperalgesia since the withdrawal motor reflex is commonly used as a surrogate pain model. DOI: http://dx.doi.org/10.7554/eLife.06195.001 PMID:25781633

  18. Emerging Roles of Filopodia and Dendritic Spines in Motoneuron Plasticity during Development and Disease

    PubMed Central

    Kanjhan, Refik; Noakes, Peter G.; Bellingham, Mark C.

    2016-01-01

    Motoneurons develop extensive dendritic trees for receiving excitatory and inhibitory synaptic inputs to perform a variety of complex motor tasks. At birth, the somatodendritic domains of mouse hypoglossal and lumbar motoneurons have dense filopodia and spines. Consistent with Vaughn's synaptotropic hypothesis, we propose a developmental unified-hybrid model implicating filopodia in motoneuron spinogenesis/synaptogenesis and dendritic growth and branching critical for circuit formation and synaptic plasticity at embryonic/prenatal/neonatal period. Filopodia density decreases and spine density initially increases until postnatal day 15 (P15) and then decreases by P30. Spine distribution shifts towards the distal dendrites, and spines become shorter (stubby), coinciding with decreases in frequency and increases in amplitude of excitatory postsynaptic currents with maturation. In transgenic mice, either overexpressing the mutated human Cu/Zn-superoxide dismutase (hSOD1G93A) gene or deficient in GABAergic/glycinergic synaptic transmission (gephyrin, GAD-67, or VGAT gene knockout), hypoglossal motoneurons develop excitatory glutamatergic synaptic hyperactivity. Functional synaptic hyperactivity is associated with increased dendritic growth, branching, and increased spine and filopodia density, involving actin-based cytoskeletal and structural remodelling. Energy-dependent ionic pumps that maintain intracellular sodium/calcium homeostasis are chronically challenged by activity and selectively overwhelmed by hyperactivity which eventually causes sustained membrane depolarization leading to excitotoxicity, activating microglia to phagocytose degenerating neurons under neuropathological conditions. PMID:26843990

  19. Analysis of the Effects of Normal Walking on Ankle Joint Contact Characteristics After Acute Inversion Ankle Sprain.

    PubMed

    Bae, Ji Yong; Park, Kyung Soon; Seon, Jong Keun; Jeon, Insu

    2015-12-01

    To show the causal relationship between normal walking after various lateral ankle ligament (LAL) injuries caused by acute inversion ankle sprains and alterations in ankle joint contact characteristics, finite element simulations of normal walking were carried out using an intact ankle joint model and LAL injury models. A walking experiment using a volunteer with a normal ankle joint was performed to obtain the boundary conditions for the simulations and to support the appropriateness of the simulation results. Contact pressure and strain on the talus articular cartilage and anteroposterior and mediolateral translations of the talus were calculated. Ankles with ruptured anterior talofibular ligaments (ATFLs) had a higher likelihood of experiencing increased ankle joint contact pressures, strains and translations than ATFL-deficient ankles. In particular, ankles with ruptured ATFL + calcaneofibular ligaments and all ruptured ankles had a similar likelihood as the ATFL-ruptured ankles. The push off stance phase was the most likely situation for increased ankle joint contact pressures, strains and translations in LAL-injured ankles. PMID:26077988

  20. Unsupported standing with minimized ankle muscle fatigue.

    PubMed

    Mihelj, Matjaz; Munih, Marko

    2004-08-01

    In the past, limited unsupported standing has been restored in patients with thoracic spinal cord injury through open-loop functional electrical stimulation of paralyzed knee extensor muscles and the support of intact arm musculature. Here an optimal control system for paralyzed ankle muscles was designed that enables the subject to stand without hand support in a sagittal plane. The paraplegic subject was conceptualized as an underactuated double inverted pendulum structure with an active degree of freedom in the upper trunk and a passive degree of freedom in the paralyzed ankle joints. Control system design is based on the minimization of a cost function that estimates the effort of ankle joint muscles via observation of the ground reaction force position, relative to ankle joint axis. Furthermore, such a control system integrates voluntary upper trunk activity and artificial control of ankle joint muscles, resulting in a robust standing posture. Figures are shown for the initial simulation study, followed by disturbance tests on an intact volunteer and several laboratory trials with a paraplegic person. Benefits of the presented methodology are prolonged standing sessions and in the fact that the subject is able to maintain voluntary control over upper body orientation in space, enabling simple functional standing. PMID:15311817

  1. Rehabilitation of Syndesmotic (High) Ankle Sprains

    PubMed Central

    Williams, Glenn N.; Allen, Eric J.

    2010-01-01

    Context: High ankle sprains are common in athletes who play contact sports. Most high ankle sprains are treated nonsurgically with a rehabilitation program. Evidence Acquisition: All years of PUBMED, Cochrane Database of Systematic Reviews, CINAHL PLUS, SPORTDiscuss, Google Scholar, and Web of Science were searched to August 2010, cross-referencing existing publications. Keywords included syndesmosis ankle sprain or high ankle sprain and the following terms: rehabilitation, treatment, cryotherapy, braces, orthosis, therapeutic modalities, joint mobilization, massage, pain, pain medications, TENS (ie, transcutaneous electric nerve stimulation), acupuncture, aquatic therapy, strength, neuromuscular training, perturbation training, and outcomes. Results: Level of evidence, 5. A 3-phase rehabilitation program is described. The acute phase is directed at protecting the joint while minimizing pain, inflammation, muscle weakness, and loss of motion. Most patients are treated with some form of immobilization and have weightbearing restrictions. A range of therapeutic modalities are used to minimize pain and inflammation. Gentle mobilization and resistance exercises are used to gain mobility and maintain muscle size and strength. The subacute phase is directed at normalizing range of motion, strength, and function in activities of daily living. Progressive mobilization and strengthening are hallmarks of this phase. Neuromuscular training is begun and becomes the central component of rehabilitation. The advanced training phase focuses on preparing the patient for return to sports participation. Perturbation of support surfaces, agility drills, plyometrics, and sport-specific training are central components of this phase. Conclusion: The rehabilitation guidelines discussed may assist clinicians in managing syndesmotic ankle sprains. PMID:23015976

  2. Sprained Ankle Could Pose Longer-Term Harms to Health

    MedlinePlus

    ... Sprained Ankle Could Pose Longer-Term Harms to Health Study finds link between adult injury, more heart ... or federal policy. Recent Health News Related MedlinePlus Health Topics Ankle Injuries and Disorders Sprains and Strains ...

  3. [Chronic ankle instability in sports -- a review for sports physicians].

    PubMed

    Valderrabano, V; Leumann, A; Pagenstert, G; Frigg, A; Ebneter, L; Hintermann, B

    2006-12-01

    Chronic ankle instability represents a typical sports injury which can mostly be seen in basketball, soccer, orienteering and other high risk sports. 20 to 40 % of the acute ankle sprains develop into chronic ankle instability. From a sports orthopaedic point of view, chronic ankle instability can be subdivided into a lateral, medial or a combination of both so called rotational ankle instability. From a pathophysiological point of view, chronic ankle instability can be either mechanical with a structural ligament lesion or functional with loss of the neuromuscular control. For the sports physician, the chronic ankle instability is a difficult entity as the diagnosis is usually complex and the therapy usually surgical. This review on chronic ankle instability addresses pathomechanism, diagnostics, indications for conservative and surgical treatments, and possible long-term sequelae, as ligamentous osteoarthritis. PMID:17279471

  4. Electrophysiological properties of laryngeal motoneurones in rats submitted to chronic intermittent hypoxia

    PubMed Central

    Moraes, Davi J A; Machado, Benedito H

    2015-01-01

    To keep an appropriate airflow to and from the lungs under physiological conditions a precise neural co-ordination of the upper airway resistance by laryngeal motoneurones in the nucleus ambiguus is essential. Chronic intermittent hypoxia (CIH), an important component of obstructive sleep apnoea, may alter these fine mechanisms. Here, using nerve and whole cell patch clamp recordings in in situ preparations of rats we investigated the effects of CIH on the respiratory control of the upper airway resistance, on the electrophysiological properties of laryngeal motoneurones in the nucleus ambiguus, and the role of carotid body (CB) afferents to the brainstem on the underlying mechanisms of these effects. CIH rats exhibited longer pre-inspiratory and lower post-inspiratory superior laryngeal nerve activities than control rats. These changes produced exaggerated glottal abduction (before inspiration) and decreased glottal adduction during post-inspiration, indicating a reduction of upper airway resistance during these respiratory phases after CIH. CB denervation abolished these changes produced by CIH. Regarding choline acetyltransferase positive-laryngeal motoneurones, CIH increased the firing frequency of inspiratory and decreased the firing frequency of post-inspiratory laryngeal motoneurones, without changes in their intrinsic electrophysiological properties. These data show that the effects of CIH on the upper airway resistance and laryngeal motoneurones activities are driven by the integrity of CB, which afferents induce changes in the central respiratory generators in the brainstem. These neural changes in the respiratory network seem to be an adaptive process required for an appropriated pulmonary ventilation and control of upper airway resistance under intermittent episodes of hypoxia. Key points The respiratory control of the glottis by laryngeal motoneurones is characterized by inspiratory abduction and post-inspiratory adduction causing decreases and

  5. Possible functions of transmitter-controlled plateau potentials in alpha motoneurones.

    PubMed

    Eken, T; Hultborn, H; Kiehn, O

    1989-01-01

    An increasing number of vertebrate central neurones has been shown to possess complex membrane properties. However, the functional significance of such properties is unclear. The aim of the present paper is to review some old and new findings in this field from this laboratory. First, a bistability in alpha motoneurones in reduced preparations is described. Thereafter we present some new data on a bistable behaviour in motor units in unrestrained intact animals during posture. Finally, the possible role of motoneuronal bistability in locomotion and in spasticity is discussed. Recently a bistable firing behaviour in motoneurones was described in the unanaesthetized decerebrate cat. This behaviour is generated by a plateau potential, which causes long-lasting excitability increase and can be initiated and terminated by short-lasting synaptic excitation and inhibition respectively, and is contingent upon activity in descending noradrenergic and serotonergic systems. In an in vitro preparation of the turtle spinal cord the plateau potential was shown to be serotonin dependent and generated by a voltage-dependent non-inactivating calcium conductance. In order to elucidate possible functional consequences of a bistable firing behaviour in the intact animal, the firing pattern of individual soleus motor units was studied by means of chronic EMG registration in awake unrestrained rats during quiet standing. Implanted electrodes allowed the delivery of excitatory and inhibitory stimulus trains to the motoneurones. It was found that short-lasting synaptic stimulation could induce maintained shifts between two stable levels of motoneurone firing frequencies, as in the decerebrate cat. Spontaneous shifts between the same two levels were also present. It seems most likely that plateau potentials are responsible for this bistable firing property in intact animals. The role of plateau potentials in locomotion is difficult to study. At present there are no clear indications of the

  6. Isolated posterior high ankle sprain: a report of three cases.

    PubMed

    Botchu, Rajesh; Allen, Patricia; Rennie, Winston J

    2013-12-01

    High ankle sprains are difficult to diagnose and account for 10% of all ankle sprains. A high index of suspicion is essential for diagnosis. High ankle sprains are managed symptomatically, with prolonged rehabilitation. The posterior inferior tibiofibular ligament is the strongest syndesmotic ligament; isolated injury of it is rare. We present 3 cases of isolated posterior high ankle sprain and discuss the relevant anatomy, mechanism of injury, and management. PMID:24366808

  7. RMI study and clinical correlations of ankle retinacula damage and outcomes of ankle sprain.

    PubMed

    Stecco, Antonio; Stecco, Carla; Macchi, Veronica; Porzionato, Andrea; Ferraro, Claudio; Masiero, Stefano; De Caro, Raffaele

    2011-12-01

    Recent studies reveal the role of the ankle retinacula in proprioception and functional stability of the ankle, but there is no clear evidence of their role in the outcomes of ankle sprain. 25 patients with outcomes of ankle sprain were evaluated by MRI to analyze possible damage to the ankle retinacula. Patients with damage were subdivided into two groups: group A comprised cases with ankle retinacula damage only, and group B those also with anterior talofibular ligament rupture or bone marrow edema. Both groups were examined by VAS, CRTA and static posturography and underwent three treatments of deep connective tissue massage (Fascial Manipulation technique). All evaluations were repeated after the end of treatment and at 1, 3 and 6 months. At MRI, alteration of at least one of the ankle retinacula was evident in 21 subjects, and a further lesion was also identified in 7 subjects. After treatment, VAS and CRTA evaluations showed a statistically significant decrease in values with respect to those before treatment (p < 0.0001). There were also significant improvements (p < 0.05) in stabilometric platform results. No significant difference was found between groups A and B. The initial benefit was generally maintained at follow-up. The alteration of retinacula at MRI clearly corresponds to the proprioceptive damage revealed by static posturography and clinical examination. Treatment focused on the retinacula may improve clinical outcomes and stabilometric data. PMID:21305286

  8. Synergistic but transient rescue effects of BDNF and GDNF on axotomized neonatal motoneurons.

    PubMed

    Vejsada, R; Tseng, J L; Lindsay, R M; Acheson, A; Aebischer, P; Kato, A C

    1998-05-01

    Brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF), members of distinct families of polypeptide growth factors, have been shown to support motoneurons under various in vitro and in vivo conditions. We used a model of motoneuron cell death induced by sciatic nerve section in newborn rats and compared the efficacy of BDNF and GDNF administered alone or simultaneously in order to determine whether combinations of neurotrophic proteins can produce more potent motoneuron rescue than individual factors. The factors were administered by different methods, including (i) a single dose on to the transected nerve, (ii) continuous delivery from implanted slow-release polymer rods (BDNF) or encapsulated cells (GDNF), and (iii) repeated systemic injections (BDNF). Irrespective of the method of administration, either factor alone produced rescue effects which dramatically declined at two weeks as compared to one week post-lesion. In contrast, this decrease was significantly reduced when BDNF and GDNF were used simultaneously provided that one factor was applied on to the nerve while the other was continuously released from the rods or capsules. Other combinations in which GDNF was replaced by ciliary neurotrophic factor or axokine-1 failed to reproduce such additive activity. Two conclusions can be made from these experiments. First, when BDNF and GDNF are administered simultaneously but by distinct routes of delivery, their survival-promoting effects on the injured developing motoneurons are potentiated; second, even continuous delivery of each of these trophic factors alone cannot completely abrogate the time-dependent decline in rescue effects in this model of motoneuron cell death. PMID:9522368

  9. Cannabinoid agonists rearrange synaptic vesicles at excitatory synapses and depress motoneuron activity in vivo.

    PubMed

    García-Morales, Victoria; Montero, Fernando; Moreno-López, Bernardo

    2015-05-01

    Impairment of motor skills is one of the most common acute adverse effects of cannabis. Related studies have focused mainly on psychomotor alterations, and little is known about the direct impact of cannabinoids (CBs) on motoneuron physiology. As key modulators of synaptic function, CBs regulate multiple neuronal functions and behaviors. Presynaptic CB1 mediates synaptic strength depression by inhibiting neurotransmitter release, via a poorly understood mechanism. The present study examined the effect of CB agonists on excitatory synaptic inputs incoming to hypoglossal motoneurons (HMNs) in vitro and in vivo. The endocannabinoid anandamide (AEA) and the synthetic CB agonist WIN 55,212-2 rapidly and reversibly induced short-term depression (STD) of glutamatergic synapses on motoneurons by a presynaptic mechanism. Presynaptic effects were fully reversed by the CB1-selective antagonist AM281. Electrophysiological and electron microscopy analysis showed that WIN 55,212-2 reduced the number of synaptic vesicles (SVs) docked to active zones in excitatory boutons. Given that AM281 fully abolished depolarization-induced depression of excitation, motoneurons can be feasible sources of CBs, which in turn act as retrograde messengers regulating synaptic function. Finally, microiontophoretic application of the CB agonist O-2545 reversibly depressed, presumably via CB1, glutamatergic inspiratory-related activity of HMNs in vivo. Therefore, evidence support that CBs, via presynaptic CB1, induce excitatory STD by reducing the readily releasable pool of SVs at excitatory synapses, then attenuating motoneuron activity. These outcomes contribute a possible mechanistic basis for cannabis-associated motor performance disturbances such as ataxia, dysarthria and dyscoordination. PMID:25595101

  10. Locomotor training modifies soleus monosynaptic motoneuron responses in human spinal cord injury

    PubMed Central

    Smith, Andrew C.; Rymer, William Zev

    2015-01-01

    The objective of this study was to assess changes in monosynaptic motoneuron responses to stimulation of Ia afferents after locomotor training in individuals with chronic spinal cord injury (SCI). We hypothesized that locomotor training modifies the amplitude of the soleus monosynaptic motoneuron responses in a body position-dependent manner. Fifteen individuals with chronic clinical motor complete or incomplete SCI received an average of 45 locomotor training sessions. The soleus H-reflex and M-wave recruitment curves were assembled using data collected in both the right and left legs, with subjects seated and standing, before and after training. The soleus H-reflexes and M-waves, measured as peak-to-peak amplitudes, were normalized to the maximal M-wave (Mmax). Stimulation intensities were normalized to 50 % Mmax stimulus intensity. A sigmoid function was also fitted to the normalized soleus H-reflexes on the ascending limb of the recruitment curve. After training, soleus H-reflex excitability was increased in both legs in AIS C subjects, and remained unchanged in AIS A-B and AIS D subjects during standing. When subjects were seated, soleus H-reflex excitability was decreased after training in many AIS C and D subjects. Changes in reflex excitability coincided with changes in stimulation intensities at H-threshold, 50 % maximal H-reflex, and at maximal H-reflex, while an interaction between leg side and AIS scale for the H-reflex slope was also found. Adaptations of the intrinsic properties of soleus motoneurons and Ia afferents, the excitability profile of the soleus motoneuron pool, oligosynaptic inputs, and corticospinal inputs may all contribute to these changes. The findings of this study demonstrate that locomotor training impacts the amplitude of the monosynaptic motoneuron responses based on the demands of the motor task in people with chronic SCI. PMID:25205562

  11. Eye Movements and Abducens Motoneuron Behavior During Cholinergically Induced REM Sleep

    PubMed Central

    Marquez-Ruiz, Javier; Escudero, Miguel

    2009-01-01

    Study objectives: The injection of cholinergic drugs in the pons has been largely used to induce REM sleep as a useful model to study different processes during this period. In the present study, microinjections of carbachol in the nucleus reticularis pontis oralis (NRPO) were performed to test the hypothesis that eye movements and the behavior of extraocular motoneurons during induced REM sleep do not differ from those during spontaneous REM sleep. Methods: Six female adult cats were prepared for chronic recording of eye movements (by means of the search-coil technique) and electroencephalography, electromyography, ponto-geniculo-occipital (PGO) waves at the lateral geniculate nucleus, and identified abducens motoneuron activities after microinjections of the cholinergic agonist carbachol into the NRPO. Results: Unilateral microinjections (n = 13) of carbachol in the NRPO induced REM sleep-like periods in which the eyes performed a convergence and downward rotation interrupted by phasic complex rapid eye movements associated to PGO waves. During induced-REM sleep abducens motoneurons lost their tonic activity and eye position codification, but continued codifying eye velocity during the burst of eye movements. Conclusion: The present results show that eye movements and the underlying behavior of abducens motoneurons are very similar to those present during natural REM sleep. Thus, microinjection of carbachol seems to activate the structures responsible for the exclusive oculomotor behavior observed during REM sleep, validating this pharmacological model and enabling a more efficient exploration of phasic and tonic phenomena underlying eye movements during REM sleep. Citation: Marquez-Ruiz J; Escudero M. Eye movements and abducens motoneuron behavior during cholinergically induced REM sleep. SLEEP 2009;32(4):471–481. PMID:19413141

  12. Delayed riluzole treatment is able to rescue injured rat spinal motoneurons.

    PubMed

    Nógrádi, A; Szabó, A; Pintér, S; Vrbová, G

    2007-01-19

    The effect of delayed 2-amino-6-trifluoromethoxy-benzothiazole (riluzole) treatment on injured motoneurons was studied. The L4 ventral root of adult rats was avulsed and reimplanted into the spinal cord. Immediately after the operation or with a delay of 5, 10, 14 or 16 days animals were treated with riluzole (n=5 in each group) while another four animals remained untreated. Three months after the operation the fluorescent dye Fast Blue was applied to the proximal end of the cut ventral ramus of the L4 spinal nerve to retrogradely label reinnervating neurons. Three days later the spinal cords were processed for counting the retrogradely labeled cells and choline acetyltransferase immunohistochemistry was performed to reveal the cholinergic cells in the spinal cords. In untreated animals there were 20.4+/-1.6 (+/-S.E.M.) retrogradely labeled neurons while in animals treated with riluzole immediately or 5 and 10 days after ventral root avulsion the number of labeled motoneurons ranged between 763+/-36 and 815+/-50 (S.E.M.). Riluzole treatment starting at 14 and 16 days after injury resulted in significantly lower number of reinnervating motoneurons (67+/-4 and 52+/-3 S.E.M., respectively). Thus, riluzole dramatically enhanced the survival and reinnervating capacity of injured motoneurons not only when treatment started immediately after injury but also in cases when riluzole treatment was delayed for up to 10 days. These results suggest that motoneurons destined to die after ventral root avulsion are programmed to survive for some time after injury and riluzole is able to rescue them during this period of time. PMID:17084537

  13. Mechanism and Function of Mixed-Mode Oscillations in Vibrissa Motoneurons

    PubMed Central

    Golomb, David

    2014-01-01

    Vibrissa motoneurons in the facial nucleus innervate the intrinsic and extrinsic muscles that move the whiskers. Their intrinsic properties affect the way they process fast synaptic input from the vIRT and Bötzinger nuclei together with serotonergic neuromodulation. In response to constant current (Iapp) injection, vibrissa motoneurons may respond with mixed mode oscillations (MMOs), in which sub-threshold oscillations (STOs) are intermittently mixed with spikes. This study investigates the mechanisms involved in generating MMOs in vibrissa motoneurons and their function in motor control. It presents a conductance-based model that includes the M-type K+ conductance, gM, the persistent Na+ conductance, gNaP, and the cationic h conductance, gh. For gh = 0 and moderate values of gM and gNaP, the model neuron generates STOs, but not MMOs, in response to Iapp injection. STOs transform abruptly to tonic spiking as the current increases. In addition to STOs, MMOs are generated for gh>0 for larger values of Iapp; the Iapp range in which MMOs appear increases linearly with gh. In the MMOs regime, the firing rate increases with Iapp like a Devil's staircase. Stochastic noise disrupts the temporal structure of the MMOs, but for a moderate noise level, the coefficient of variation (CV) is much less than one and varies non-monotonically with Iapp. Furthermore, the estimated time period between voltage peaks, based on Bernoulli process statistics, is much higher in the MMOs regime than in the tonic regime. These two phenomena do not appear when moderate noise generates MMOs without an intrinsic MMO mechanism. Therefore, and since STOs do not appear in spinal motoneurons, the analysis can be used to differentiate different MMOs mechanisms. MMO firing activity in vibrissa motoneurons suggests a scenario in which moderate periodic inputs from the vIRT and Bötzinger nuclei control whisking frequency, whereas serotonergic neuromodulation controls whisking amplitude. PMID

  14. Interpretation of the ankle in UHECR

    NASA Astrophysics Data System (ADS)

    Berezinsky, Veniamin

    Ankle is a flattening in CR spectrum observed first in Volcano Ranch experiment in 1963 at E _{a} ˜ 10 EeV, and it was interpreted as transition from galactic to extragalactic CRs. Since that time the ankle was observed in all large UHECR detectors and most recently in HiRes, TA and Auger detectors at E _{a} ˜ 4 - 5 EeV. At present there are two interpretations of the ankle: as transition from galactic to extragalactic CRs (the conventional interpretation) and as a part of the dip, produced by extragalactic protons interacting with the CMB photons. These two interpretations will be discussed in the light of recent observations and models of UHECR origin.

  15. Osteochondral defects in the ankle: why painful?

    PubMed Central

    Reilingh, Mikel L.; Zengerink, Maartje; van Bergen, Christiaan J. A.

    2010-01-01

    Osteochondral defects of the ankle can either heal and remain asymptomatic or progress to deep ankle pain on weight bearing and formation of subchondral bone cysts. The development of a symptomatic OD depends on various factors, including the damage and insufficient repair of the subchondral bone plate. The ankle joint has a high congruency. During loading, compressed cartilage forces its water into the microfractured subchondral bone, leading to a localized high increased flow and pressure of fluid in the subchondral bone. This will result in local osteolysis and can explain the slow development of a subchondral cyst. The pain does not arise from the cartilage lesion, but is most probably caused by repetitive high fluid pressure during walking, which results in stimulation of the highly innervated subchondral bone underneath the cartilage defect. Understanding the natural history of osteochondral defects could lead to the development of strategies for preventing progressive joint damage. PMID:20151110

  16. Proprioception and ankle injuries in soccer.

    PubMed

    Ergen, Emin; Ulkar, Bülent

    2008-01-01

    Because soccer attracts many participants and leads to a substantial number of injuries, especially of the lower extremities, it is important to study possibilities for injury prevention and proper rehabilitation to return safely to activities. Ankle sprains can be prevented by external ankle supports and proprioceptive-coordination training, especially in athletes with previous ankle sprains. Proprioception is a broad concept that includes balance and postural control with visual and vestibular contributions, joint kinesthesia, position sense, and muscle reaction time. Proprioceptive feedback is crucial in the conscious and unconscious awareness of a joint or limb in motion. Enhancement of functional joint stability by proprioceptive (or neuromuscular) training is important both in prevention and rehabilitation of athletic injuries. PMID:18206575

  17. Ankle pain and peroneal tendon pathology.

    PubMed

    Baumhauer, Judith F; Nawoczenski, Deborah A; DiGiovanni, Benedict F; Flemister, A Samuel

    2004-01-01

    Chronic ankle pain can be due to multiple causes. A thorough review of the patient's history with a physical examination concentrating on anatomic structures surrounding the ankle is imperative. The most common of causes have been presented. The addition of provocative testing and radiographic examinations can aid in elucidating the pathology. After treatment of the injury, attention to training technique, shoe and insert usage as well as individual gait abnormalities are integrated into global patient education to decrease the incidence of injury recurrence. PMID:15062582

  18. Ankle injuries and the family physician.

    PubMed

    Birrer, R B

    1988-01-01

    In transmitting the body's weight, the ankle is subject to frequent static and dynamic injury due to concentrated stresses during standing and movement. The frequency of athletic ankle injuries ranges from 10 to 90 percent, with the highest rate occurring in basketball players. There is prolonged disability and recurrent instability for months to years for 25 to 40 per cent of these patients. Because most of this trauma is handled by primary care physicians, this review presents the mechanism of injury, relevant anatomy, physical examination, and appropriate therapeutic intervention in the acute and rehabilitative phases. PMID:3146894

  19. Sprained ankles as they relate to the basketball player.

    PubMed

    Johnson, K A; Teasdall, R D

    1993-04-01

    Concepts based on newer medical information concerning ankle injuries have changed in recent years. With these changing concepts, the method of treatment has also changed. It is the purpose of this article to review some of the commonly known information concerning ankle sprains, to emphasize the association of subtalar injury with the ankle sprain complex, to outline new information concerning the static stabilizers on the lateral aspect of the ankle, and finally, to utilize this information in producing a rationale for a new type of surgical treatment for chronic instability of the ankle. PMID:8481971

  20. Therapeutic Interventions for Increasing Ankle Dorsiflexion After Ankle Sprain: A Systematic Review

    PubMed Central

    Terada, Masafumi; Pietrosimone, Brian G.; Gribble, Phillip A.

    2013-01-01

    Context: Clinicians perform therapeutic interventions, such as stretching, manual therapy, electrotherapy, ultrasound, and exercises, to increase ankle dorsiflexion. However, authors of previous studies have not determined which intervention or combination of interventions is most effective. Objective: To determine the magnitude of therapeutic intervention effects on and the most effective therapeutic interventions for restoring normal ankle dorsiflexion after ankle sprain. Data Sources: We performed a comprehensive literature search in Web of Science and EBSCO HOST from 1965 to May 29, 2011, with 19 search terms related to ankle sprain, dorsiflexion, and intervention and by cross-referencing pertinent articles. Study Selection: Eligible studies had to be written in English and include the means and standard deviations of both pretreatment and posttreatment in patients with acute, subacute, or chronic ankle sprains. Outcomes of interest included various joint mobilizations, stretching, local vibration, hyperbaric oxygen therapy, electrical stimulation, and mental-relaxation interventions. Data Extraction: We extracted data on dorsiflexion improvements among various therapeutic applications by calculating Cohen d effect sizes with associated 95% confidence intervals (CIs) and evaluated the methodologic quality using the Physiotherapy Evidence Database (PEDro) scale. Data Synthesis: In total, 9 studies (PEDro score = 5.22 ± 1.92) met the inclusion criteria. Static-stretching interventions with a home exercise program had the strongest effects on increasing dorsiflexion in patients 2 weeks after acute ankle sprains (Cohen d = 1.06; 95% CI = 0.12, 2.42). The range of effect sizes for movement with mobilization on ankle dorsiflexion among individuals with recurrent ankle sprains was small (Cohen d range = 0.14 to 0.39). Conclusions: Static-stretching intervention as a part of standardized care yielded the strongest effects on dorsiflexion after acute ankle sprains. The

  1. Hypocretin (orexin) input to trigeminal and hypoglossal motoneurons in the cat: a double-labeling immunohistochemical study.

    PubMed

    Fung, S J; Yamuy, J; Sampogna, S; Morales, F R; Chase, M H

    2001-06-01

    In trigeminal and hypoglossal motor nuclei of adult cats, hypocretin immunoreactive fiber varicosities were observed in apposition to retrogradely labeled motoneuron somata and dendrites. Among those lateral hypothalamus neurons that project to the hypoglossal nucleus some were determined to be hypocretin immunoreactive and were located amongst the single-labeled hypocretinergic neurons. These data suggest that hypocretin may play a role in the synaptic control of these motoneurons. PMID:11382413

  2. Neuronal nitric oxide synthase inhibitor, 7-nitroindazole, delays motor dysfunction and spinal motoneuron degeneration in the wobbler mouse.

    PubMed

    Ikeda, K; Iwasaki, Y; Kinoshita, M

    1998-09-18

    Gene mutations of superoxide dismutase (SOD) have been discovered in familial amyotrophic lateral sclerosis (ALS). Neuronal nitric oxide synthase (NOS), endothelial NOS and 3-nitrotyrosine immunoreactivities are selectively increased in the spinal motoneurons of sporadic ALS. Other study suggests that 3-nitrotyrosine immunoreactivity is enhanced in the spinal motoneurons of sporadic and familial ALS patients. The hypothesis is postulated that increased production of radical species, such as superoxide and peroxynitrite, may cause motoneuron degeneration in ALS. There are increased amounts of nitric oxide and SOD hypoactivities in the brain and spinal cord of wobbler mice. NOS is also induced in the vacuolated spinal motoneurons or axons in this animal. Free radicals might contribute to the pathogenesis of wobbler mouse motoneuron disease. Lecithinized SOD treatment has retarded the progression of this disease. This evidence allowed us to determine whether NOS inhibitors delay progression of wobbler mouse motoneuron disease. After clinical diagnosis at age 3-4 weeks, wobbler mice were injected with intraperitoneal non-selective NOS inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME, 50 mg/kg), two doses of neuronal NOS inhibitor, 7-nitroindazole (5 or 50 mg/kg) or a vehicle solution, daily for 4 weeks in a blind fashion. In comparison with vehicle, 7-nitroindazole-treated mice potentiated grip strength and attenuated deformities in the forelimbs. 7-Nitroindazole treatment increased the biceps muscle weight, reduced denervation muscle atrophy, and suppressed degeneration of spinal motoneurons. To a lesser degree, L-NAME-treated mice displayed slowed progression of disease. The present studies indicate that neuronal NOS inhibitor may be a candidate for promising therapy in lower motoneuron disease or motor neuropathy. PMID:9804111

  3. An in Silico Analysis of Ankle Joint Loads in Secondary Ankle Osteoarthritis. Case Study.

    PubMed

    Lorkowski, Jacek; Mrzygłód, Mirosław W; Grzegorowska, Oliwia; Kotela, Ireneusz

    2015-01-01

    Secondary, post-traumatic, degenerative lesions of the ankle joint remain a serious clinical challenge. This paper presents the case of a 66-year-old patient with secondary, post-traumatic ankle osteoarthritis and subchondral cysts. The use of rapid computer modelling FEM 2D enabled optimization of surgical treatment. A FEM 2D model of biomechanical changes in bones may help in streamlining treatment as well as improve our understanding of the pathomechanism of osteoarthritis. PMID:26248632

  4. Effectiveness of an outside-the-boot ankle brace in reducing parachuting related ankle injuries

    PubMed Central

    Schmidt, M; Sulsky, S; Amoroso, P

    2005-01-01

    Objectives: To examine the efficacy of an outside-the-boot parachute ankle brace (PAB) in reducing risk of ankle injury to army paratrooper trainees and to identify inadvertent risks associated with PAB use. Design: The authors compared hospitalization rates for ankle, musculoskeletal, and other traumatic injury among 223 172 soldiers trained 1985–2002 in time periods defined by presence/absence of PAB use protocols. Multiple logistic regression analysis estimated adjusted odds ratios (OR) and 95% confidence intervals for injury outcomes, comparing pre and post brace periods to the brace protocol period. Setting: A research database consisting of training rosters from the US Army Airborne training facility (Fort Benning, GA) occupational, demographic, and hospitalization information. Main outcome measures: Injuries were considered training related if they occurred during a five week period starting with first scheduled static line parachute jump and a parachuting cause of injury code appeared in the hospital record. Results: Of 939 parachuting related hospitalizations during the defined risk period, 597 (63.6%) included an ankle injury diagnosis, 198 (21.1%) listed a musculoskeletal (non-ankle) injury, and 69 (7.3%) cited injuries to multiple body parts. Risk of ankle injury hospitalization was higher during both pre-brace (adjusted OR 2.38, 95% CI 1.92 to 2.95) and post-brace (adjusted OR 1.72, 95% CI 1.27 to 2.32) periods compared with the brace protocol period. Odds of musculoskeletal (non-ankle) injury or injury to multiple body parts did not change between the brace and post-brace periods. Conclusion: Use of a PAB during airborne training appears to reduce risk of ankle injury without increasing risk of other types of traumatic injury. PMID:15933409

  5. Ankle Ligament Healing After an Acute Ankle Sprain: An Evidence-Based Approach

    PubMed Central

    Hubbard, Tricia J; Hicks-Little, Charlie A

    2008-01-01

    Objective: To perform a systematic review to determine the healing time of the lateral ankle ligaments after an acute ankle sprain. Data Sources: We identified English-language research studies from 1964 to 2007 by searching MEDLINE, Physiotherapy Evidence Database (PEDro), SportDiscus, and CINAHL using the terms ankle sprain, ankle rehabilitation, ankle injury, ligament healing, and immobilization. Study Selection: We selected studies that described randomized, controlled clinical trials measuring ligament laxity either objectively or subjectively immediately after injury and at least 1 more time after injury. Data Extraction: Two reviewers independently scored the 7 studies that met the inclusion criteria. Because of differences in study designs, a meta-analysis could not be performed. Effect sizes and confidence intervals could be calculated only for 1 study. The percentages of subjective and objective instability were calculated for the remaining studies. Data Synthesis: Ankle laxity improved over a period of 6 weeks to 1 year. One author showed stress talar tilt values of 16.10 ± 8.8° immediately after injury and 3.4 ± 3.6° at 3 months after injury. In 2 articles, the authors reported that positive anterior drawer tests were still present in 3% to 31% of participants at 6 months after injury. Additionally, feelings of instability affected 7% to 42% of participants up to 1 year after injury. Conclusions/Recommendations: In the studies that we examined, it took at least 6 weeks to 3 months before ligament healing occurred. However, at 6 weeks to 1 year after injury, a large percentage of participants still had objective mechanical laxity and subjective ankle instability. Direct comparison among articles is difficult because of differences in methods. More research focusing on more reliable methods of measuring ankle laxity is needed so that clinicians can know how long ligament healing takes after injury. This knowledge will help clinicians to make better

  6. Factors Contributing to Chronic Ankle Instability: A Strength Perspective

    PubMed Central

    Kaminski, Thomas W.; Hartsell, Heather D.

    2002-01-01

    Objective: To examine the concept of dynamic ankle stability and closely critique the relevant research over the past 50+ years focusing on strength as it relates to those with chronic ankle instability (CAI). Data Sources: We reviewed the literature regarding the assessment of strength related to CAI. We searched MEDLINE and ISI Web of Science from 1950 through 2001 using the key words functional ankle instability, chronic ankle instability, strength, ankle stability, chronic ankle dysfunction, and isokinetics. Data Synthesis: An overview of dynamic stability in the ankle is established, followed by a comprehensive discussion involving the variables used to assess ankle strength. Additionally, a historical look at deficits in muscular stability leading to CAI is provided, and a compilation of numerous contemporary approaches examining strength as it relates to CAI is presented. Conclusions/Recommendations: Although strength is an important consideration during ankle rehabilitation, deficits in ankle strength are not highly correlated with CAI. More contemporary approaches involving the examination of reciprocal muscle-group ratios as a measure of strength have recently been investigated and offer an insightful, albeit different, avenue for future exploration. Evidence pertaining to the effects of strength training on those afflicted with CAI is lacking, including what, if any, implication strength training has on the various measures of ankle strength. PMID:12937561

  7. Rehabilitation of the Ankle After Acute Sprain or Chronic Instability

    PubMed Central

    Mattacola, Carl G.; Dwyer, Maureen K.

    2002-01-01

    Objective: To outline rehabilitation concepts that are applicable to acute and chronic injury of the ankle, to provide evidence for current techniques used in the rehabilitation of the ankle, and to describe a functional rehabilitation program that progresses from basic to advanced, while taking into consideration empirical data from the literature and clinical practice. Background: Important considerations in the rehabilitation of ankle injuries include controlling the acute inflammatory process, regaining full ankle range of motion, increasing muscle strength and power, and improving proprioceptive abilities. These goals can be achieved through various modalities, flexibility exercises, and progressive strength- and balance-training exercises. In this article, we discuss the deleterious effects of ankle injury on ankle-joint proprioception and muscular strength and how these variables can be quantifiably measured to follow progress through a rehabilitation program. Evidence to support the effectiveness of applying orthotics and ankle braces during the acute and subacute phases of ankle rehabilitation is provided, along with recommendations for functional rehabilitation of ankle injuries, including a structured progression of exercises. Recommendations: Early functional rehabilitation of the ankle should include range-of-motion exercises and isometric and isotonic strength-training exercises. In the intermediate stage of rehabilitation, a progression of proprioception-training exercises should be incorporated. Advanced rehabilitation should focus on sport-specific activities to prepare the athlete for return to competition. Although it is important to individualize each rehabilitation program, this well-structured template for ankle rehabilitation can be adapted as needed. PMID:12937563

  8. EGb761 protects motoneurons against avulsion-induced oxidative stress in rats

    PubMed Central

    2010-01-01

    Background Root avulsion of the brachial plexus causes an oxidative stress reaction in the spinal cord and induces dramatic spinal motoneuron death, while EGb761 is a natural free radical cleaning agent. This study was designed to investigate the protective effects of intraperitoneally injected EGb761 against neural damage following brachial root avulsion. Methods The effect of EGb761 on avulsion-induced motoneuron injury was studied in 26 total groups of (n) rats, treated as follows. Animals in singular number groups received EGb761(50 mg/kg.d) and those in complex number groups received normal saline solution (i.p.), serving as controls. Groups 1-8 were used for the determination of nitric oxide (NO) levels in the serum and injured spinal cord at the 5 d, 2 w, 4 w, and 6 w time points. Groups 9-16 were used for determination of constitutive nitric oxide synthase (cNOS) and inducible nitric oxide synthase (iNOS) levels in injured spinal cord at the 5 d, 2 w, 4 w, and 6 w time points. Groups 17-26 were used for determination of the number of neuronal nitric oxide synthase (nNOS)-positive and surviving motoneurons in injured C7 ventral horn at the 5 d, 2 w, 4 w, 6 w and 8 w time points. Results Compared to control groups, the EGb761 treatment group not only had significant decreased levels of NO in serum at 2 w and 6 w after avulsion, but also had reduced levels of NO specifically in the spinal cord at 2 w, 4 w and 6 w. The cNOS activity in the spinal cord was also significant decreased at 2 w and 4 w, while the iNOS activity in injured C6-T1 spinal segments was reduced at 2 w, 4 w and 6 w. All together, the percentages of NADPH-d positive motoneurons in an injured C7 segment were down-regulated and the number of surviving motoneurons in injured C7 ventral horn was increased at 2 w, 4 w, 6 w and 8 w in treated versus untreated animals. Conclusions Intraperitoneal administration of EGb761 after root avulsion of the brachial plexus exerted protective effects by

  9. Assessment of the Injured Ankle in the Athlete

    PubMed Central

    Lynch, Scott A.

    2002-01-01

    Objective: To present appropriate tools to assist in the assessment and evaluation of ankle injuries in athletes. Data Sources: A MEDLINE search was performed for the years 1980–2001 using the terms ankle injuries and ankle sprains. Data Synthesis: Ankle sprains are the most common injuries sustained by athletes. In order to render appropriate treatment, a proper evaluation must be made. Assessment of ankle injuries includes obtaining a good history of the mechanism of injury, a thorough physical examination, and judicious use of radiographic evaluation and special tests. I will outline techniques for diagnosing the most common ankle injuries among athletes. Conclusions/Recommendations: In order to provide appropriate treatment, the examiner must differentiate among injuries to the lateral ankle-ligament complex, subtalar joint, deltoid ligament, and syndesmosis. It is important to realize that injury can occur to any or all of these structures simultaneously. PMID:12937562

  10. Total Ankle Arthroplasty: An Overview of the Canadian Experience.

    PubMed

    Latham, Warren C W; Lau, Johnny T C

    2016-06-01

    Total ankle arthroplasty use has increased across Canada over the last two decades. Multiple implant designs are readily available and implanted across Canada. Although arthrodesis is a reliable procedure for treating end-stage ankle arthritis, ankle replacement is often the preferred surgical treatment by patients. A recent prospective study evaluated intermediate-term outcomes of ankle replacement and arthrodesis at multiple centers across Canada, with variability in prosthesis type, surgeon, and surgical technique. Intermediate-term clinical outcomes of total ankle replacement and ankle arthrodesis were comparable in a diverse cohort in which treatment was tailored to patient presentation; however, rates of reoperation and major complications were higher after ankle replacement. PMID:27261806

  11. The influence of a 5-wk whole body vibration on electrophysiological properties of rat hindlimb spinal motoneurons.

    PubMed

    Baczyk, M; Hałuszka, A; Mrówczyński, W; Celichowski, J; Krutki, P

    2013-06-01

    The study aimed at determining the influence of a whole body vibration (WBV) on electrophysiological properties of spinal motoneurons. The WBV training was performed on adult male Wistar rats, 5 days a week, for 5 wk, and each daily session consisted of four 30-s runs of vibration at 50 Hz. Motoneuron properties were investigated intracellularly during experiments on deeply anesthetized animals. The experimental group subjected to the WBV consisted of seven rats, and the control group of nine rats. The WBV treatment induced no significant changes in the passive membrane properties of motoneurons. However, the WBV-evoked adaptations in excitability and firing properties were observed, and they were limited to fast-type motoneurons. A significant decrease in rheobase current and a decrease in the minimum and the maximum currents required to evoke steady-state firing in motoneurons were revealed. These changes resulted in a leftward shift of the frequency-current relationship, combined with an increase in slope of this curve. The functional relevance of the described adaptive changes is the ability of fast motoneurons of rats subjected to the WBV to produce series of action potentials at higher frequencies in a response to the same intensity of activation. Previous studies proved that WBV induces changes in the contractile parameters predominantly of fast motor units (MUs). The data obtained in our experiment shed a new light to possible explanation of these results, suggesting that neuronal factors also play a substantial role in MU adaptation. PMID:23486208

  12. Decreased succinate dehydrogenase activity of gamma and alpha motoneurons in mouse spinal cords following 13 weeks of exposure to microgravity.

    PubMed

    Ishihara, Akihiko; Nagatomo, Fumiko; Fujino, Hidemi; Kondo, Hiroyo; Ohira, Yoshinobu

    2013-10-01

    Cell body size and succinate dehydrogenase activity of motoneurons in the dorsolateral region of the ventral horn in the lumbar and cervical segments of the mouse spinal cord were assessed after long-term exposure to microgravity and compared with those of ground-based controls. Mice were housed in a mouse drawer system on the International Space Station for 13 weeks. The mice were transported to the International Space Station by the Space Shuttle Discovery and returned to Earth by the Space Shuttle Atlantis. No changes in the cell body size of motoneurons were observed in either segment after exposure to microgravity, but succinate dehydrogenase activity of small-sized (<300 μm(2)) gamma and medium-sized (300-700 μm(2)) alpha motoneurons, which have higher succinate dehydrogenase activity than large-sized (>700 μm(2)) alpha motoneurons, in both segments was lower than that of ground-based controls. We concluded that exposure to microgravity for longer than 3 months induced decreased succinate dehydrogenase activity of both gamma and slow-type alpha motoneurons. In particular, the decreased succinate dehydrogenase activity of gamma motoneurons was observed only after long-term exposure to microgravity. PMID:23943522

  13. Neonatal motoneurons overexpressing the bcl-2 protooncogene in transgenic mice are protected from axotomy-induced cell death.

    PubMed Central

    Dubois-Dauphin, M; Frankowski, H; Tsujimoto, Y; Huarte, J; Martinou, J C

    1994-01-01

    In vitro, the overexpression of the bcl-2 protooncogene in cultured neurons has been shown to prevent apoptosis induced by neurotrophic factor deprivation. We have generated transgenic mice overexpressing the Bcl-2 protein in neurons, including motoneurons of the facial nucleus. We have tested whether Bcl-2 could protect these motoneurons from experimentally induced cell death in new born mice. To address this question, we performed unilateral lesion of the facial nerve of wild-type and transgenic 2-day-old mice. In wild-type mice, the lesioned nerve and the corresponding motoneuron cell bodies in the facial nucleus underwent rapid degeneration. In contrast, in transgenic mice, facial motoneurons survived axotomy. Not only their cell bodies but also their axons were protected up to the lesion site. These results demonstrate that in vivo Bcl-2 protects neonatal motoneurons from degeneration after axonal injury. A better understanding of the mechanisms by which Bcl-2 prevents neuronal cell death in vivo could lead to the development of strategies for the treatment of motoneuron degenerative diseases. Images PMID:8159744

  14. The afterhyperpolarization conductance exerts the same control over the gain and variability of motoneurone firing in anaesthetized cats

    PubMed Central

    Manuel, Marin; Meunier, Claude; Donnet, Maud; Zytnicki, Daniel

    2006-01-01

    Does the afterhyperpolarization current control the gain and discharge variability of motoneurones according to the same law? We investigated this issue in lumbar motoneurones of anaesthetized cats. Using dynamic clamp, we measured the conductance, time constant and driving force of the AHP current in a sample of motoneurones and studied how the gain was correlated to these quantities. To study the action of the AHP on the discharge variability and to compare it to its action on the gain, we injected an artificial AHP-like current in motoneurones. This increased the natural AHP. In three motoneurones, we abolished most of the natural AHP with the calcium chelator BAPTA to investigate the condition where the discharge was essentially controlled by the artificial AHP. Our results demonstrate that both the gain and the coefficient of variation of the firing rate are inversely proportional to the magnitude and to the time constant of the artificial AHP conductance. This indicates that the AHP exerts the same control over the gain and the variability. This mechanism ensures that the variability of the discharge is modulated with the gain. This guarantees a great regularity of the discharge when the motoneurone is in a low excitability state and hence good control of the force produced. PMID:16931549

  15. The CES-2-related transcription factor E4BP4 is an intrinsic regulator of motoneuron growth and survival.

    PubMed

    Junghans, Dirk; Chauvet, Sophie; Buhler, Emmanuelle; Dudley, Keith; Sykes, Toby; Henderson, Christopher E

    2004-09-01

    The regulation of neuronal growth and survival during development requires interplay between extrinsic and intrinsic factors. Among the latter, transcription factors play a key role. In the nematode, the transcription factor CES-2 predisposes neurosecretory motoneurons to death, whereas E4BP4 (NFIL3), one of its vertebrate homologs, regulates survival of pro-B lymphocytes. We show that E4BP4 is expressed by embryonic rat and chicken motoneurons in vivo, with levels being highest in neurons that survive the period of naturally occurring cell death. Overexpression of E4BP4 by electroporation of purified motoneurons in culture protected them almost completely against cell death triggered by removal of neurotrophic factors or activation of death receptors. Moreover, E4BP4 strongly enhanced neuronal cell size and axonal growth. Axons of motoneurons transfected with E4BP4 were 3.5-fold longer than control neurons grown on laminin; this effect required the activity of PI3 kinase. In vivo, overexpression of E4BP4 in chicken embryos reduced the number of dying motoneurons by 45%. Our results define E4BP4 as a novel intrinsic regulator of motoneuron growth and survival. Pathways regulated by E4BP4 are of potential interest both for understanding neuromuscular development and for promoting neuronal survival and regeneration in pathological situations. PMID:15306565

  16. Invariant ankle moment patterns when walking with and without a robotic ankle exoskeleton

    PubMed Central

    Kao, Pei-Chun; Lewis, Cara L.; Ferris, Daniel P.

    2009-01-01

    To guide development of robotic lower limb exoskeletons, it is necessary to understand how humans adapt to powered assistance. The purposes of this study were to quantify joint moments while healthy subjects adapted to a robotic ankle exoskeleton and to determine if the period of motor adaptation is dependent on the magnitude of robotic assistance. The pneumatically-powered ankle exoskeleton provided plantar flexor torque controlled by the wearer’s soleus electromyography (EMG). Eleven naïve individuals completed two 30-min sessions walking on a split-belt instrumented treadmill at 1.25 m/s while wearing the ankle exoskeleton. After two sessions of practice, subjects reduced their soleus EMG activation by ~36% and walked with total ankle moment patterns similar to their unassisted gait (r2 = 0.98±0.02, THSD, p>0.05). They had substantially different ankle kinematic patterns compared to their unassisted gait (r2 = 0.79±0.12, THSD, p<0.05). Not all of the subjects reached a steady state gait pattern within the two sessions, in contrast to a previous study using a weaker robotic ankle exoskeleton (Gordon and Ferris 2007). Our results strongly suggest that humans aim for similar joint moment patterns when walking with robotic assistance rather than similar kinematic patterns. In addition, greater robotic assistance provided during initial use results in a longer adaptation process than lesser robotic assistance. PMID:19878952

  17. Invariant ankle moment patterns when walking with and without a robotic ankle exoskeleton.

    PubMed

    Kao, Pei-Chun; Lewis, Cara L; Ferris, Daniel P

    2010-01-19

    To guide development of robotic lower limb exoskeletons, it is necessary to understand how humans adapt to powered assistance. The purposes of this study were to quantify joint moments while healthy subjects adapted to a robotic ankle exoskeleton and to determine if the period of motor adaptation is dependent on the magnitude of robotic assistance. The pneumatically powered ankle exoskeleton provided plantar flexor torque controlled by the wearer's soleus electromyography (EMG). Eleven naïve individuals completed two 30-min sessions walking on a split-belt instrumented treadmill at 1.25m/s while wearing the ankle exoskeleton. After two sessions of practice, subjects reduced their soleus EMG activation by approximately 36% and walked with total ankle moment patterns similar to their unassisted gait (r(2)=0.98+/-0.02, THSD, p>0.05). They had substantially different ankle kinematic patterns compared to their unassisted gait (r(2)=0.79+/-0.12, THSD, p<0.05). Not all of the subjects reached a steady-state gait pattern within the two sessions, in contrast to a previous study using a weaker robotic ankle exoskeleton (Gordon and Ferris, 2007). Our results strongly suggest that humans aim for similar joint moment patterns when walking with robotic assistance rather than similar kinematic patterns. In addition, greater robotic assistance provided during initial use results in a longer adaptation process than lesser robotic assistance. PMID:19878952

  18. Imaging of the foot and ankle.

    PubMed

    Pavlov, H

    1990-09-01

    The foot and ankle are subjected to daily stresses and strains ranging from normal walking activities to the excessive forces encountered in the active sports enthusiast. These traumatic events as well as systemic and local arthritic conditions and tumors can be temporarily or permanently disabling. Early, expedited, and cost-efficient diagnosis is the daily challenge for the radiologist, clinician, and patient. PMID:1975109

  19. Treatment algorithm for chronic lateral ankle instability

    PubMed Central

    Giannini, Sandro; Ruffilli, Alberto; Pagliazzi, Gherardo; Mazzotti, Antonio; Evangelisti, Giulia; Buda, Roberto; Faldini, Cesare

    2014-01-01

    Summary Introduction: ankle sprains are a common sports-related injury. A 20% of acute ankle sprains results in chronic ankle instability, requiring surgery. Aim of this paper is to report the results of a series of 38 patients treated for chronic lateral ankle instability with anatomic reconstruction. Materials and methods: thirty-eight patients were enrolled in the study. Seventeen patients underwent a surgical repair using the Brostrom-modified technique, while the remaining underwent anatomic reconstruction with autologous or allogenic graft. Results: at a mean follow-up of 5 years the AOFAS score improved from 66.1 ± 5.3 to 92.2 ± 5.6. Discussion: the findings of this study confirm that anatomic reconstruction is an effective procedure with satisfactory subjective and objective results which persist at long-term follow-up along with a low complication rate. No differences, in term of clinical and functional outcomes, were observed between the Brostrom-modified repair and the anatomic reconstruction technique. Level of evidence: level IV. PMID:25767783

  20. [Ankle sprain during a volleyball game].

    PubMed

    Boersma, Anton R; Munzebrock, Arvid V E

    2015-01-01

    A 27-year old woman was admitted to the emergency room after her left ankle rolled inward during a volleyball game. On physical examination a bony prominence on the lateral side of the left foot was noticeable, without neurovascular injury. An X-ray (anterior-posterior view) showed a subtalar dislocation without associated fractures. PMID:26420145

  1. Projections of pyramidal tract cells to alpha-motoneurones innervating hind-limb muscles in the monkey.

    PubMed Central

    Jankowska, E; Padel, Y; Tanaka, R

    1975-01-01

    1. We have investigated the spatial organization of monosynaptic corticospinal projections to hind-limb motoneurones, using near threshold stimulation of the surface of the precentral gyrus to activate pyramidal tract (PT) cells and intracellular recording from motoneurones to detect the resulting e.p.s.p.s. 2. Monosynaptic e.p.s.p.s. of cortical origin were seen in all motoneurone species investigated, those of distal as well as of proximal hind-limb muscles. The proportion of motoneurones in which the e.s.p.s. were evoked and the amplitudes of the latter indicated a more extensive cortical projection to motor nuclei for distal than for proximal muscles, as previously found for forelimb motoneurones. 3. Cortical areas from which monosynaptic e.p.s.p.s. were evoked in individual motoneurones were remarkably large, most often between 3 and 7 mm2. Several motoneurones appeared to have two or three separate areas within the hind-limb division of the motor cortex. 4. Areas of location of pyramidal tract cells projecting to various motoneurones innervating one muscle were usually not identical. They overlapped often only partially or did not overlap at all. 5. Areas of location of pyramidal tract cells projecting to motor nuclei for different muscles often showed an extensive overlap. When it occurred, various motoneurones of a given motor nucleus had common cortical projection areas with motoneurones of other motor nuclei, either to synergistic or to antagonistic muscles. Our results give further evidence for overlapping of areas of cortical projections to motoneurones and speak against a mosaic-like organization of pyramidal tract cells projecting to different motor nuclei. 6. The rise times of cortically evoked e.p.s.p.s. indicate that the corticospinal tract fibres terminate on motoneurones at approximately similar distances from the soma as group Ia afferents. The small amplitudes of the majority of e.p.s.p.s. evoked by near threshold cortical stimulation therefore

  2. Osteochondral Allografts in the Ankle Joint

    PubMed Central

    Vannini, Francesca; Buda, Roberto; Ruffilli, Alberto; Cavallo, Marco; Giannini, Sandro

    2013-01-01

    Purpose: The aim of this systematic review is to report about the clinical use of partial and total fresh osteochondral allograft in the ankle joint. The state of the art of allografts with regard to basic science, procurement and storage methods, immunogenicity, generally accepted indications and contraindications, and the rationale of the allografting procedure have been described. Methods: All studies published in PubMed from 2000 to January 2012 addressing fresh osteochondral allograft procedures in the ankle joint were identified, including those that fulfilled the following criteria: (a) level I-IV evidence addressing the areas of interest outlined above; (b) measures of functional, clinical, or imaging outcome; and (c) outcome related to ankle cartilage lesions or ankle arthritis treated by allografts. Results: The analysis showed a progressively increasing number of articles from 2000. The number of selected articles was 14; 9 of those focused on limited dimension allografts (plugs, partial) and 5 on bipolar fresh osteochondral allografts. The evaluation of evidence level showed 14 case series and no randomized studies. Conclusions: Fresh osteochondral allografts are now a versatile and suitable option for the treatment of different degrees of osteochondral disease in the ankle joint and may even be used as total joint replacement. Fresh osteochondral allografts used for total joint replacement are still experimental and might be considered as a salvage procedure in otherwise unsolvable situations. A proper selection of the patients is therefore a key point. Moreover, the patients should be adequately informed about the possible risks, benefits, and alternatives to the allograft procedure. PMID:26069666

  3. Ankle positions and exercise intervals effect on the blood flow velocity in the common femoral vein during ankle pumping exercises

    PubMed Central

    Toya, Kaori; Sasano, Ken; Takasoh, Tomomi; Nishimoto, Teppei; Fujimoto, Yuta; Kusumoto, Yasuaki; Yoshimatsu, Tatsuki; Kusaka, Satomi; Takahashi, Tetsuya

    2016-01-01

    [Purpose] The aim of this study was to identify the most effective method of performing ankle pumping exercises. [Subjects and Methods] The study subjects were 10 men. We measured time-averaged maximum flow velocity and peak systolic velocity in the common femoral vein using a pulse Doppler method with a diagnostic ultrasound system during nine ankle pumping exercises (three different ankle positions and three exercise intervals). Changes of blood flow velocity during ankle pumping exercises with different ankle positions and exercise intervals were compared. [Result] Peak systolic velocity of the leg-up position showed significantly lower values than those of the supine and head-up positions. For all exercise intervals, the increased amount of blood flow velocity in the leg-up position was significantly lower than that in the head-up and supine positions. [Conclusion] Ankle positions and exercise intervals must be considered when performing effective ankle pumping exercises. PMID:27065564

  4. Descending pathways to the cutaneus trunci muscle motoneuronal cell group in the cat

    NASA Technical Reports Server (NTRS)

    Holstege, Gert; Blok, Bertil F.

    1989-01-01

    The descending pathways to the motoneuronal cell group of the cutaneous trunci muscle (CTM) of the cat were investigated by injecting H-3-labeled lucine into the brain stem, the diencephalon, or the C1, C2, C6, and C8 segments of the spinal cord, and examining fixed autoradiographic sections of the spinal cord and brain regions. Results demonstrate presence of specific supraspinal projectons to the CTM motor nucleus originating in the contralateral nucleus retroambiguous and the ipsilateral dorsolateral pontine tegmentum. Results also suggest that propriospinal pathways to the CTM motor nucleus originating in the cervical cord do not exist, although these propriospinal projections to all other motoneuronal cell groups surrounding the CTM nucleus are very strong.

  5. Physiological consequences of doublet discharges on motoneuronal firing and motor unit force.

    PubMed

    Mrówczyński, Włodzimierz; Celichowski, Jan; Raikova, Rositsa; Krutki, Piotr

    2015-01-01

    The double discharges are observed at the onset of contractions of mammalian motor units (MUs), especially during their recruitment to strong or fast movements. Doublets lead to MU force increase and improve ability of muscles to maintain high force during prolonged contractions. In this review we discuss an ability to produce doublets by fast and slow motoneurons (MNs), their influence on the course of action potential afterhyperpolarization (AHP) as well as its role in modulation of the initial stage of the firing pattern of MNs. In conclusion, a generation of doublets is an important strategy of motor control, responsible for fitting the motoneuronal firing rate to the optimal for MUs at the start of their contraction, necessary for increment of muscle force. PMID:25805972

  6. Neuropathology in respiratory-related motoneurons in young Pompe (Gaa(-/-)) mice.

    PubMed

    Turner, Sara M F; Hoyt, Aaron K; ElMallah, Mai K; Falk, Darin J; Byrne, Barry J; Fuller, David D

    2016-06-15

    Respiratory and/or lingual dysfunction are among the first motor symptoms in Pompe disease, a disorder resulting from absence or dysfunction of the lysosomal enzyme acid α-glucosidase (GAA). Here, we histologically evaluated the medulla, cervical and thoracic spinal cords in 6 weeks old asymptomatic Pompe (Gaa(-/-)) mice to determine if neuropathology in respiratory motor regions has an early onset. Periodic acid-Schiff (PAS) staining indicated glycogen accumulation was exclusively occurring in Gaa(-/-) hypoglossal, mid-cervical and upper thoracic motoneurons. Markers of DNA damage (Tunel) and ongoing apoptosis (Cleaved Caspase 3) did not co-localize with PAS staining, but were prominent in a medullary region which included the nucleus tractus solitarius, and also in the thoracic spinal dorsal horn. We conclude that respiratory-related motoneurons are particularly susceptible to GAA deficiency and that neuronal glycogen accumulation and neurodegeneration may occur independently in early stage disease. The data support early therapeutic intervention in Pompe disease. PMID:26921786

  7. A multimodal approach to ankle instability: Interrelations between subjective and objective assessments of ankle status in athletes.

    PubMed

    Golditz, Tobias; Welsch, Goetz H; Pachowsky, Milena; Hennig, Friedrich F; Pfeifer, Klaus; Steib, Simon

    2016-03-01

    The aim of this retrospective cohort study is to investigate the association between different subjective and objective assessments of ankle function in a population of athletes with or without functional ankle instability (FAI). 29 athletes with a history of ankle spraining were divided into two groups according to their ankle status: 16 with FAI (initial ankle sprain with residual functional instability) (age 24.6 ± 3.1 years), and 13 COPERS (initial ankle sprain without residual instability) (age 25.3 ± 4.4 years). The assessment of each individual's ankle function was based on three approaches: The "functional-ankle-ability-measure" (FAAM) assessing subjective ankle functionality, measures of sensorimotor control as objective functional measurements and MRI-based T2-mapping as a quantitative marker of compositional joint status. Pearson's product-moment-correlation coefficient, student's t-test and analysis-of-variance were used for statistical analysis. Significant group differences existed for subjective ankle function (FAAM, p = 0.04) and MRI-data mainly in the medial compartment of the ankle joint (p ≤ 0.05). We found unique associations between T2-mapping results and sensorimotor scores in the COPER (r = -0.756-0.849), and "FAI"-group (r = 0.630-0.657). The location and magnitude differed between groups. No correlations existed between these measures and the FAAM. This exploratory study provides preliminary evidence for potential interrelations between various diagnostic measures of ankle function and structure in individuals with and without FAI. We found associations between MRI-results and selected measures of sensorimotor control, indicating a potential link between loss of ankle function and early joint degeneration. Despite these interrelations, each of the different assessment options appears to contain unique information on ankle functionality important in a clinical assessment. PMID:26309042

  8. Corticospinal Inputs to Primate Motoneurons Innervating the Forelimb from Two Divisions of Primary Motor Cortex and Area 3a

    PubMed Central

    Witham, Claire L.; Fisher, Karen M.; Edgley, Steve A.

    2016-01-01

    Previous anatomical work in primates has suggested that only corticospinal axons originating in caudal primary motor cortex (“new M1”) and area 3a make monosynaptic cortico-motoneuronal connections with limb motoneurons. By contrast, the more rostral “old M1” is proposed to control motoneurons disynaptically via spinal interneurons. In six macaque monkeys, we examined the effects from focal stimulation within old and new M1 and area 3a on 135 antidromically identified motoneurons projecting to the upper limb. EPSPs with segmental latency shorter than 1.2 ms were classified as definitively monosynaptic; these were seen only after stimulation within new M1 or at the new M1/3a border (incidence 6.6% and 1.3%, respectively; total n = 27). However, most responses had longer latencies. Using measures of the response facilitation after a second stimulus compared with the first, and the reduction in response latency after a third stimulus compared with the first, we classified these late responses as likely mediated by either long-latency monosynaptic (n = 108) or non-monosynaptic linkages (n = 108). Both old and new M1 generated putative long-latency monosynaptic and non-monosynaptic effects; the majority of responses from area 3a were non-monosynaptic. Both types of responses from new M1 had significantly greater amplitude than those from old M1. We suggest that slowly conducting corticospinal fibers from old M1 generate weak late monosynaptic effects in motoneurons. These may represent a stage in control of primate motoneurons by the cortex intermediate between disynaptic output via an interposed interneuron seen in nonprimates and the fast direct monosynaptic connections present in new M1. SIGNIFICANCE STATEMENT The corticospinal tract in Old World primates makes monosynaptic connections to motoneurons; previous anatomical work suggests that these connections come only from corticospinal tract (CST) neurons in the subdivision of primary motor cortex within the

  9. Activation patterns of embryonic chick hind-limb muscles following blockade of activity and motoneurone cell death.

    PubMed Central

    Landmesser, L T; Szente, M

    1986-01-01

    Motoneurone cell death and spontaneous embryonic motility were blocked in chick embryos by daily in ovo injections of d-tubocurarine from stage 28-36 (E5-10). Isolated spinal cord-hind-limb preparations were prepared from these embryos and movement sequences in response to electrical stimulation of the thoracic cord were assessed, after drug wash-out, by electromyogram (e.m.g.) or muscle-nerve recordings. In embryos in which complete blockade of lumbar motoneurone cell death was later confirmed histologically, flexor and extensor motoneurone pools were found to be activated in alternating bursts as occurs in control embryos. Thus the development of the basic cord circuits responsible for these patterns of motoneurone activation does not require motoneurone cell death. Partial blockade of motoneurone cell death by guanosine 3',5'-phosphate (cyclic GMP) was also without effect on muscle activation patterns. In ovo injection of d-tubocurarine or alpha-bungarotoxin in doses sufficient to block embryonic motility was found to have a direct effect on the spinal cord, preventing the patterned activation of motoneurone pools in alternating bursts. Cords removed from treated embryos behaved similarly to cords in which these drugs were applied acutely in the bath. Minor changes in muscle activation patterns that occurred with chronic drug treatment were also observed in acutely treated cords and appear to be a direct and persistent effect of the drugs on cord circuits. It is possible to conclude that cholinergic circuits within the chick lumbar cord play a role in the normal patterned activation of flexor and extensor motoneurone pools. Systemically applied drugs can have access to these circuits, indicating a need for caution when interpreting the results of drugs applied in this manner to developing embryos. We also conclude that neither the activation of motoneurones in patterned bursts, nor the afferent feed-back from the movements that result, are required to form the

  10. Calpain Inhibition Protected Spinal Cord Motoneurons against 1-methyl-4-phenylpyridinium ion and Rotenone

    PubMed Central

    Samantaray, Supriti; Knaryan, Varduhi H.; Le Gal, Charlene; Ray, Swapan K.; Banik, Naren L.

    2011-01-01

    Parkinson's disease (PD), characterized by selective midbrain nigrostriatal dopaminergic degeneration, is consistently associated with moderate systemic mitochondrial dysfunction. Downstream degeneration of spinal cord has also been suggested in PD, although the mechanisms have not been much investigated. In the present study, two mitochondrial toxicants, 1-methyl-4-phenylpyridinium ion (MPP+) and rotenone were tested in ventral spinal cord (VSC 4.1) motoneuronal cells. Cell death was assessed by morphological and biochemical means to discern a lower apoptosis-inducing concentration and LC50, which were subsequently compared in further cytoprotection experiments. Mitochondrial toxicants dose-dependently induced increase in intracellular free Ca2+ level, which was conducive for increased expression and activities of Ca2+-activated neutral protease calpain and downstream caspase-3. Thus, mitochondrial damage triggered apoptotic mechanisms in spinal cord motoneurons. Inhibition of calpain by calpeptin significantly attenuated damaging effects of MPP+ and rotenone on motoneurons, especially at low apoptosis-inducing concentrations of toxicants and partly at their LC50, as demonstrated by absence of DNA ladder formation and decrease in TUNEL-positive cells. Cytoprotection by calpeptin was observed with marked decreases in Bax:Bcl-2 ratio and activities of calpain and caspase-3, which affirmed the role of mitochondrial dysfunction and involvement of intrinsic pathway in mediation of apoptosis. These findings strongly suggested that parkinsonian toxicants MPP+ and rotenone at low doses induced cascade of cell damaging effects in spinal cord motoneurons, thus, highlighting the possibility of induction of apoptotic mechanisms in these cells, when subjected to mitochondrial stress. Cytoprotection rendered by calpeptin further validated the involvement of calpain in apoptosis and suggested calpain inhibition as a potential neuroprotective strategy. PMID:21723922

  11. Eye Movements and Abducens Motoneuron Behavior after Cholinergic Activation of the Nucleus Reticularis Pontis Caudalis

    PubMed Central

    Márquez-Ruiz, Javier; Escudero, Miguel

    2010-01-01

    Study Objectives: The aim of this work was to characterize eye movements and abducens (ABD) motoneuron behavior after cholinergic activation of the nucleus reticularis pontis caudalis (NRPC). Methods: Six female adult cats were prepared for chronic recording of eye movements (using the scleral search-coil technique), electroencephalography, electromyography, ponto-geniculo-occipital (PGO) waves in the lateral geniculate nucleus, and ABD motoneuron activities after microinjections of the cholinergic agonist carbachol into the NRPC. Results: Unilateral microinjections of carbachol in the NRPC induced tonic and phasic phenomena in the oculomotor system. Tonic effects consisted of ipsiversive rotation to the injected side, convergence, and downward rotation of the eyes. Phasic effects consisted of bursts of rhythmic rapid eye movements directed contralaterally to the injected side along with PGO-like waves in the lateral geniculate and ABD nuclei. Although tonic effects were dependent on the level of drowsiness, phasic effects were always present and appeared along with normal saccades when the animal was vigilant. ABD motoneurons showed phasic activities associated with ABD PGO-like waves during bursts of rapid eye movements, and tonic and phasic activities related to eye position and velocity during alertness. Conclusion The cholinergic activation of the NRPC induces oculomotor phenomena that are somewhat similar to those described during REM sleep. A precise comparison of the dynamics and timing of the eye movements further suggests that a temporal organization of both NRPCs is needed to reproduce the complexity of the oculomotor behavior during REM sleep. Citation: Márquez-Ruiz J; Escudero M. Eye movements and abducens motoneuron behavior after cholinergic activation of the nucleus reticularis pontis caudalis. SLEEP 2010;33(11):1517-1527. PMID:21102994

  12. Repetitive doublet firing of motor units: evidence for plateau potentials in human motoneurones?

    PubMed

    Kudina, Lydia P; Andreeva, Regina E

    2010-07-01

    During voluntary muscle contraction, human motoneurones can exhibit specific discharge patterns: single and repetitive doublets. Delayed depolarization has been accepted as the mechanism underlying single doublets. Repetitive doublet firing has been studied much less and its controlling mechanisms remain obscure. The aim of the present study was to examine properties of repetitive doublets in human motoneurones and to consider their underlying potential mechanisms. It was found that 22 of 41 (53.7%) lower-threshold motor units (MUs) in the trapezius and 15 of 42 (35.7%) MUs in triceps brachii displayed repetitive doublets with the mean interspike intervals (ISIs) of 5.5 +/- 1.1 and 6.4 +/- 2.6 ms, respectively. Each doublet was followed by a prolonged post-doublet ISI. The analysis of properties of repetitive doublets showed that they were typically initiated in quiescent motoneurones rather than in firing ones (appearing just at recruitment in an all-or-none manner) and could only be maintained at a certain level of muscle contraction. Repetitive doublets were interrupted either voluntarily (by the subject), or spontaneously with sudden transition from doublet firing to single discharges-the firing behaviour that may be referred to as a firing-pattern "jump". The properties of doublet firing seem to be consistent with traits of motoneurone firing in the presence of plateau potentials reported in animal studies. It was suggested that the potential mechanisms underlying repetitive doublet firing could include a delayed depolarization as the primary determinant, which likely could become persistent probably due to a plateau potential activated in parallel with a common synaptic input. PMID:20508919

  13. Synaptic action of R beta neurons on phrenic motoneurons studied with spike-triggered averaging.

    PubMed

    Lipski, J; Kubin, L; Jodkowski, J

    1983-12-12

    The functional role of dorsal medullary inspiratory neurons with excitatory input from lung stretch receptors (R beta neurons) is a matter of controversy. The present study, performed on chloralose-anesthetized and paralyzed cats, ventilated mainly with a phrenic-controlled servorespirator, deals with the spinal projection of these neurons, a property which suggests their involvement in the efferent part of the medullary respiratory complex. Out of 37 inspiratory neurons which could be excited antidromically following microstimulation within the contralateral C6 phrenic nucleus (latency 2.0 ms +/- 0.4, S.D.), 17 were classified by the 'no-inflation' test as R beta. Intracellular recording of synaptic potentials from phrenic motoneurons using the 'spike-triggered averaging' technique were made. In 10 phrenic motoneurons, the averaging revealed individual EPSPs (peak amplitude 150 +/- 110 microV, rise time 0.5 +/- 0.2 ms) time-locked to action potentials of 5 out of 7 R beta neurons tested. Cross-correlation of the R beta neurons firing with the activity of C5 and C6 phrenic rootlets indicated a divergence of excitatory action within the phrenic nucleus. For comparison, in 3 phrenic motoneurons individual EPSPs were recorded when the activity of 3 R alpha cells was used to trigger the averaging. It is concluded that at least some R beta neurons, similarly to R alpha neurons, project to the contralateral phrenic nucleus and can make monosynaptic excitatory connections with phrenic motoneurons. The finding that individual EPSPs were similar when averaging was triggered by the activity of either R beta or R alpha neurons provides new evidence for our earlier hypothesis that bulbospinal inspiratory neurons of the solitary tract nucleus may be subdivided into two categories only on a quantitative basis. PMID:6661613

  14. Design of a simple, lightweight, passive-elastic ankle exoskeleton supporting ankle joint stiffness

    NASA Astrophysics Data System (ADS)

    Kim, Seyoung; Son, Youngsu; Choi, Sangkyu; Ham, Sangyong; Park, Cheolhoon

    2015-09-01

    In this study, a passive-elastic ankle exoskeleton (PEAX) with a one-way clutch mechanism was developed and then pilot-tested with vertical jumping to determine whether the PEAX is sufficiently lightweight and comfortable to be used in further biomechanical studies. The PEAX was designed to supplement the function of the Achilles tendon and ligaments as they passively support the ankle torque with their inherent stiffness. The main frame of the PEAX consists of upper and lower parts connected to each other by tension springs (N = 3) and lubricated hinge joints. The upper part has an offset angle of 5° with respect to the vertical line when the springs are in their resting state. Each spring has a slack length of 8 cm and connects the upper part to the tailrod of the lower part in the neutral position. The tailrod freely rotates with low friction but has a limited range of motion due to the stop pin working as a one-way clutch. Because of the one-way clutch system, the tension springs store the elastic energy only due to an ankle dorsiflexion when triggered by the stop pin. This clutch mechanism also has the advantage of preventing any inconvenience during ankle plantarflexion because it does not limit the ankle joint motion during the plantarflexion phase. In pilot jumping tests, all of the subjects reported that the PEAX was comfortable for jumping due to its lightweight (approximately 1 kg) and compact (firmly integrated with shoes) design, and subjects were able to nearly reach their maximum vertical jump heights while wearing the PEAX. During the countermovement jump, elastic energy was stored during dorsiflexion by spring extension and released during plantarflexion by spring restoration, indicating that the passive spring torque (i.e., supportive torque) generated by the ankle exoskeleton partially supported the ankle joint torque throughout the process.

  15. Evidence-based treatment for ankle injuries: a clinical perspective

    PubMed Central

    Lin, Chung-Wei Christine; Hiller, Claire E; de Bie, Rob A

    2010-01-01

    The most common ankle injuries are ankle sprain and ankle fracture. This review discusses treatments for ankle sprain (including the management of the acute sprain and chronic instability) and ankle fracture, using evidence from recent systematic reviews and randomized controlled trials. After ankle sprain, there is evidence for the use of functional support and non-steroidal anti-inflammatory drugs. There is weak evidence suggesting that the use of manual therapy may lead to positive short-term effects. Electro-physical agents do not appear to enhance outcomes and are not recommended. Exercise may reduce the occurrence of recurrent ankle sprains and may be effective in managing chronic ankle instability. After surgical fixation for ankle fracture, an early introduction of activity, administered via early weight-bearing or exercise during the immobilization period, may lead to better outcomes. However, the use of a brace or orthosis to enable exercise during the immobilization period may also lead to a higher rate of adverse events, suggesting that this treatment regimen needs to be applied judiciously. After the immobilization period, the focus of treatment for ankle fracture should be on a progressive exercise program. PMID:21655420

  16. Acute and chronic lateral ankle instability in the athlete.

    PubMed

    Chan, Keith W; Ding, Bryan C; Mroczek, Kenneth J

    2011-01-01

    Ankle sprain injuries are the most common injury sustained during sporting activities. Three-quarters of ankle injuries involve the lateral ligamentous complex, comprised of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), and the posterior talofibular ligament (PTFL). The most common mechanism of injury in lateral ankle sprains occurs with forced plantar flexion and inversion of the ankle as the body's center of gravity rolls over the ankle. The ATFL followed by the CFL are the most commonly injured ligaments. Eighty percent of acute ankle sprains make a full recovery with conservative management, while 20% of acute ankle sprains develop mechanical or functional instability, resulting in chronic ankle instability. Treatment of acute ankle sprains generally can be successfully managed with a short period of immobilization that is followed by functional rehabilitation. Patients with chronic ankle instability who fail functional rehabilitation are best treated with a Brostrom-Gould anatomic repair or, in those patients with poor tissue quality or undergoing revision surgery, an anatomic reconstruction. PMID:21332435

  17. An Avirulent Mutant of Rabies Virus Is Unable To Infect Motoneurons In Vivo and In Vitro

    PubMed Central

    Coulon, Patrice; Ternaux, Jean-Pierre; Flamand, Anne; Tuffereau, Christine

    1998-01-01

    An antigenic double mutant of rabies virus (challenge virus standard [CVS] strain) was selected by successive use of two neutralizing antiglycoprotein monoclonal antibodies, both specific for antigenic site III. This mutant differed from the original virus strain by two amino acid substitutions in the ectodomain of the glycoprotein. The lysine in position 330 and the arginine in position 333 were replaced by asparagine and methionine, respectively. This double mutant was not pathogenic for adult mice. When injected intramuscularly into the forelimbs of adult mice, this virus could not penetrate the nervous system, either by the motor or by the sensory route, while respective single mutants infected motoneurons in the spinal cord and sensory neurons in the dorsal root ganglia. In vitro experiments showed that the double mutant was able to infect BHK cells, neuroblastoma cells, and freshly prepared embryonic motoneurons, albeit with a lower efficiency than the CVS strain. Upon further incubation at 37°C, the motoneurons became resistant to infection by the mutant while remaining permissive to CVS infection. These results suggest that rabies virus uses different types of receptors: a molecule which is ubiquitously expressed at the surface of continuous cell lines and which is recognized by both CVS and the double mutant and a neuron-specific molecule which is not recognized by the double mutant. PMID:9420224

  18. Concomitant changes in afterhyperpolarization and twitch following repetitive stimulation of fast motoneurones and motor units.

    PubMed

    Krutki, P; Mrówczyński, W; Raikova, R; Celichowski, J

    2014-02-01

    The study aimed at determining changes in a course of motoneuronal afterhyperpolarization (AHP) and in contractile twitches of motor units (MUs) during activity evoked by increasing number of stimuli (from 1 to 5), at short interspike intervals (5 ms). The stimulation was applied antidromically to spinal motoneurones or to isolated axons of MUs of the medial gastrocnemius muscle within two separate series of experiments on anesthetized rats. Alterations in the amplitude and time parameters of the AHP of successive spikes were compared to changes in force and time course of successive twitches obtained by mathematical subtraction of tetanic contractions evoked by one to five stimuli. The extent of changes of the studied parameters depended on a number of applied stimuli. The maximal modulation of the AHP and twitch parameters (a prolongation and an increase in the AHP and twitch amplitudes) was typically observed after the second pulse, while higher number of pulses at the same frequency did not induce so prominent changes. One may conclude that changes observed in parameters of action potentials of motoneurons are concomitant to changes in contractile properties of MU twitches. This suggests that both modulations of the AHP and twitch parameters reflect mechanisms leading to force development at the beginning of MU activity. PMID:24202237

  19. Influence of developmental nicotine exposure on spike-timing precision and reliability in hypoglossal motoneurons.

    PubMed

    Powell, Gregory L; Levine, Richard B; Frazier, Amanda M; Fregosi, Ralph F

    2015-03-15

    Smoothly graded muscle contractions depend in part on the precision and reliability of motoneuron action potential generation. Whether or not a motoneuron generates spikes precisely and reliably depends on both its intrinsic membrane properties and the nature of the synaptic input that it receives. Factors that perturb neuronal intrinsic properties and/or synaptic drive may compromise the temporal precision and the reliability of action potential generation. We have previously shown that developmental nicotine exposure (DNE) alters intrinsic properties and synaptic transmission in hypoglossal motoneurons (XIIMNs). Here we show that the effects of DNE also include alterations in spike-timing precision and reliability, and spike-frequency adaptation, in response to sinusoidal current injection. Current-clamp experiments in brainstem slices from neonatal rats show that DNE lowers the threshold for spike generation but increases the variability of spike-timing mechanisms. DNE is also associated with an increase in spike-frequency adaptation and reductions in both peak and steady-state firing rate in response to brief, square wave current injections. Taken together, our data indicate that DNE causes significant alterations in the input-output efficiency of XIIMNs. These alterations may play a role in the increased frequency of obstructive apneas and altered suckling strength and coordination observed in nicotine-exposed neonatal humans. PMID:25552642

  20. A putative neuronal network controlling the activity of the leg motoneurons of the stick insect.

    PubMed

    Toth, Tibor I; Daun-Gruhn, Silvia

    2011-12-21

    It is widely accepted that the electrical activity of motoneurons that drive locomotion in the stick insect are controlled by two separate mechanisms: (i) the frequency of the activity through the central pattern generator, which provides the rhythm of movement during locomotion and (ii) the 'magnitude' through circuits distinct from the earlier one. In this study, we show a possible way of how this control mechanism might be implemented in the nervous system of the stick insect by means of a network model. To do this, we had to define the 'magnitude' of the neuronal activity more precisely as the average number of spikes per unit time. The model was constructed on the basis of relevant electrophysiological and morphological data. However, only their integration in the model led to the novel properties that enable the network quickly to adapt the motoneuronal activity to central commands or sensory signals by changing both the firing pattern and intensity of the motoneuron discharges. The network would thus act as the controlling network for each of the muscle pairs that move the individual joints in each of the legs. Our model may contribute to a better understanding of the mechanisms that underlie the fast adaptive control of locomotion in this, and possibly in other types of locomotor systems. PMID:22089647

  1. Subthreshold excitatory activity and motoneuron discharge during REM periods of active sleep.

    PubMed

    Chase, M H; Morales, F R

    1983-09-16

    A striking paradox of the rapid eye movement periods of active sleep, which are typically characterized by the exacerbation of somatomotor atonia, is the occurrence of muscle twitches and jerks. The purpose of this study was to examine the specific motoneuron membrane potential processes responsible for these myoclonic patterns of activity. In lumbar motoneurons, examined intracellularly in the cat prepared for long-term study, these processes consisted of recurrent depolarizing membrane potential shifts and spontaneous action potentials that were either full-sized or of partial amplitude. In addition, the invasion of antidromically induced spikes into the soma was often blocked. Hyperpolarizing potentials were evident in the intervals between spontaneous spikes. Hyperpolarization was also observed immediately before depolarization and spike activity, in contrast to the gradual depolarization of the motoneuron membrane potential that always occurred during wakefulness. Thus, during rapid eye movement periods, in conjunction with muscle twitches and jerks, a strong excitatory input is superimposed on a background of inhibitory input. The unique patterns of membrane potential change that arise thus seem to result from the simultaneous coactivation of excitatory and inhibitory processes. PMID:6310749

  2. Transient down-regulation and restoration of glycogen synthase levels in axotomized rat facial motoneurons.

    PubMed

    Takezawa, Yosuke; Kohsaka, Shinichi; Nakajima, Kazuyuki

    2014-10-24

    In adult rats, transection of the facial nerve causes a functional down-regulation of motoneurons and glial activation/proliferation. It has not been clear how energy-supplying systems are regulated in an axotomized facial nucleus. Here we investigated the regulation of molecules involved in glycogen degradation/synthesis in axotomized facial nuclei in rats. Immunoblotting revealed that the amounts of glycogen phosphorylase in the contralateral and ipsilateral nuclei were unchanged for the first 14 days, whereas the amount of glycogen synthase in the axotomized facial nuclei was significantly decreased from days 7-14 post-insult. A quantitative analysis estimated that the glycogen synthase levels in the transected nucleus were reduced to approx. 50% at 14 days post-injury. An immunohistochemical study showed that the injured motoneurons had decreased expressions of glycogen synthase proteins. The glycogen synthase levels in the axotomized facial nucleus had returned to control levels by 5 weeks post-insult, as had the cholinergic markers. The immunohistochemical study also revealed the recovery of glycogen synthase levels at the later stage. The glycogen phosphorylase levels in the injured nucleus were not significantly changed during weeks 3-5 post-insult. Taken together, these results demonstrated that the injured facial motoneurons transiently reduced glycogen synthase levels at around 1-2 weeks post-insult, but restored the levels at 4-5 weeks post-insult. PMID:25152465

  3. Axon-somatic back-propagation in detailed models of spinal alpha motoneurons

    PubMed Central

    Balbi, Pietro; Martinoia, Sergio; Massobrio, Paolo

    2015-01-01

    Antidromic action potentials following distal stimulation of motor axons occasionally fail to invade the soma of alpha motoneurons in spinal cord, due to their passing through regions of high non-uniformity. Morphologically detailed conductance-based models of cat spinal alpha motoneurons have been developed, with the aim to reproduce and clarify some aspects of the electrophysiological behavior of the antidromic axon-somatic spike propagation. Fourteen 3D morphologically detailed somata and dendrites of cat spinal alpha motoneurons have been imported from an open-access web-based database of neuronal morphologies, NeuroMorpho.org, and instantiated in neurocomputational models. An axon hillock, an axonal initial segment and a myelinated axon are added to each model. By sweeping the diameter of the axonal initial segment (AIS) and the axon hillock, as well as the maximal conductances of sodium channels at the AIS and at the soma, the developed models are able to show the relationships between different geometric and electrophysiological configurations and the voltage attenuation of the antidromically traveling wave. In particular, a greater than usually admitted sodium conductance at AIS is necessary and sufficient to overcome the dramatic voltage attenuation occurring during antidromic spike propagation both at the myelinated axon-AIS and at the AIS-soma transitions. PMID:25729362

  4. Static γ-motoneurones couple group Ia and II afferents of single muscle spindles in anaesthetised and decerebrate cats

    PubMed Central

    Gladden, M H; Matsuzaki, H

    2002-01-01

    Ideas about the functions of static γ-motoneurones are based on the responses of primary and secondary endings to electrical stimulation of single static γ-axons, usually at high frequencies. We compared these effects with the actions of spontaneously active γ-motoneurones. In anaesthetised cats, afferents and efferents were recorded in intramuscular nerve branches to single muscle spindles. The occurrence of γ-spikes, identified by a spike shape recognition system, was linked to video-taped contractions of type-identified intrafusal fibres in the dissected muscle spindles. When some static γ-motoneurones were active at low frequency (< 15 Hz) they coupled the firing of group Ia and II afferents. Activity of other static γ-motoneurones which tensed the intrafusal fibres appeared to enhance this effect. Under these conditions the secondary ending responded at shorter latency than the primary ending. In another series of experiments on decerebrate cats, responses of primary and secondary endings of single muscle spindles to activation of γ-motoneurones by natural stimuli were compared with their responses to electrical stimulation of single γ-axons supplying the same spindle. Electrical stimulation mimicked the natural actions of γ-motoneurones on either the primary or the secondary ending, but not on both together. However, γ-activity evoked by natural stimuli coupled the firing of afferents with the muscle at constant length, and also when it was stretched. Analysis showed that the timing and tightness of this coupling determined the degree of summation of excitatory postsynaptic potentials (EPSPs) evoked by each afferent in α-motoneurones and interneurones contacted by terminals of both endings, and thus the degree of facilitation of reflex actions of group II afferents. PMID:12181298

  5. Treadmill training induced lumbar motoneuron dendritic plasticity and behavior recovery in adult rats after a thoracic contusive spinal cord injury.

    PubMed

    Wang, Hongxing; Liu, Nai-Kui; Zhang, Yi Ping; Deng, Lingxiao; Lu, Qing-Bo; Shields, Christopher B; Walker, Melissa J; Li, Jianan; Xu, Xiao-Ming

    2015-09-01

    Spinal cord injury (SCI) is devastating, causing sensorimotor impairments and paralysis. Persisting functional limitations on physical activity negatively affect overall health in individuals with SCI. Physical training may improve motor function by affecting cellular and molecular responses of motor pathways in the central nervous system (CNS) after SCI. Although motoneurons form the final common path for motor output from the CNS, little is known concerning the effect of exercise training on spared motoneurons below the level of injury. Here we examined the effect of treadmill training on morphological, trophic, and synaptic changes in the lumbar motoneuron pool and on behavior recovery after a moderate contusive SCI inflicted at the 9th thoracic vertebral level (T9) using an Infinite Horizon (IH, 200 kDyne) impactor. We found that treadmill training significantly improved locomotor function, assessed by Basso-Beattie-Bresnahan (BBB) locomotor rating scale, and reduced foot drops, assessed by grid walking performance, as compared with non-training. Additionally, treadmill training significantly increased the total neurite length per lumbar motoneuron innervating the soleus and tibialis anterior muscles of the hindlimbs as compared to non-training. Moreover, treadmill training significantly increased the expression of a neurotrophin brain-derived neurotrophic factor (BDNF) in the lumbar motoneurons as compared to non-training. Finally, treadmill training significantly increased synaptic density, identified by synaptophysin immunoreactivity, in the lumbar motoneuron pool as compared to non-training. However, the density of serotonergic terminals in the same regions did not show a significant difference between treadmill training and non-training. Thus, our study provides a biological basis for exercise training as an effective medical practice to improve recovery after SCI. Such an effect may be mediated by synaptic plasticity, and neurotrophic modification in the

  6. Cardiotrophin-1, a muscle-derived cytokine, is required for the survival of subpopulations of developing motoneurons.

    PubMed

    Oppenheim, R W; Wiese, S; Prevette, D; Armanini, M; Wang, S; Houenou, L J; Holtmann, B; Gotz, R; Pennica, D; Sendtner, M

    2001-02-15

    Developing motoneurons require trophic support from their target, the skeletal muscle. Despite a large number of neurotrophic molecules with survival-promoting activity for isolated embryonic motoneurons, those factors that are required for motoneuron survival during development are still not known. Cytokines of the ciliary neurotrophic factor (CNTF)-leukemia inhibitory factor (LIF) family have been shown to play a role in motoneuron (MN) survival. Importantly, in mice lacking the LIFRbeta or the CNTFRalpha there is a significant loss of MNs during embryonic development. Because genetic deletion of either (or both) CNTF or LIF fails, by contrast, to perturb MN survival before birth, it was concluded that another ligand exists that is functionally inactivated in the receptor deleted mice, resulting in MN loss during development. One possible candidate for this ligand is the CNTF-LIF family member cardiotrophin-1 (CT-1). CT-1 is highly expressed in embryonic skeletal muscle, secreted by myotubes, and promotes the survival of cultured embryonic mouse and rat MNs. Here we show that ct-1 deficiency causes increased motoneuron cell death in spinal cord and brainstem nuclei of mice during a period between embryonic day 14 and the first postnatal week. Interestingly, no further loss was detectable during the subsequent postnatal period, and nerve lesion in young adult ct-1-deficient mice did not result in significant additional loss of motoneurons, as had been previously observed in mice lacking both CNTF and LIF. CT-1 is the first bona fide muscle-derived neurotrophic factor to be identified that is required for the survival of subgroups of developing motoneurons. PMID:11160399

  7. Diminished Foot and Ankle Muscle Volumes in Young Adults With Chronic Ankle Instability

    PubMed Central

    Feger, Mark A.; Snell, Shannon; Handsfield, Geoffrey G.; Blemker, Silvia S.; Wombacher, Emily; Fry, Rachel; Hart, Joseph M.; Saliba, Susan A.; Park, Joseph S.; Hertel, Jay

    2016-01-01

    Background: Patients with chronic ankle instability (CAI) have demonstrated altered neuromuscular function and decreased muscle strength when compared with healthy counterparts without a history of ankle sprain. Up to this point, muscle volumes have not been analyzed in patients with CAI to determine whether deficits in muscle size are present following recurrent sprain. Purpose: To analyze intrinsic and extrinsic foot and ankle muscle volumes and 4-way ankle strength in young adults with and without CAI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Five patients with CAI (mean age, 23.0 ± 4 years; 1 male, 4 females) and 5 healthy controls (mean age, 23.8 ± 4.5 years; 1 male, 4 females) volunteered for this study. Novel fast-acquisition magnetic resonance imaging (MRI) was used to scan from above the femoral condyles through the foot and ankle. The perimeter of each muscle was outlined on each axial slice and then the 2-dimensional area was multiplied by the slice thickness (5 mm) to calculate the muscle volume. Plantar flexion, dorsiflexion, inversion, and eversion isometric strength were measured using a handheld dynamometer. Patients with CAI were compared with healthy controls on all measures of muscle volume and strength. Extrinsic muscle volumes of patients with CAI were also compared with a normative database of healthy controls (n = 24) by calculating z scores for each muscle individually for each CAI subject. Results: The CAI group had smaller total shank, superficial posterior compartment, soleus, adductor hallucis obliqus, and flexor hallucis brevis muscle volumes compared with healthy controls as indicated by group means and associated 90% CIs that did not overlap. Cohen d effect sizes for the significant group differences were all large and ranged from 1.46 to 3.52, with 90% CIs that did not cross zero. The CAI group had lower eversion, dorsiflexion, and 4-way composite ankle strength, all with group means and associated 90

  8. Effects of Nintendo Wii Fit Plus training on ankle strength with functional ankle instability

    PubMed Central

    Kim, Ki-Jong; Jun, Hyun-Ju; Heo, Myoung

    2015-01-01

    [Purpose] The objective of this study was to examine the effects of a training program using the Nintendo Wii Fit Plus on the ankle muscle strengths of subjects with functional ankle instability. [Subjects and Methods] This study was conducted using subjects in their 20s who had functional ankle instability. They were randomized to a strengthening training group and a balance training group with 10 subjects in each, and they performed an exercise using Nintendo Wii Fit Plus for 20 minutes. In addition, every participant completed preparation and finishing exercises for 5 minutes, respectively. [Results] The muscle strengths after conducting plantar flexion and dorsiflexion significantly increased at the angular velocities of 60° and 120° in the strengthening training group. Furthermore, the muscle strengths after conducting plantar flexion, dorsiflexion, eversion, and inversion significantly increased at the angular velocities of 60° and 120° in the balance training group. [Conclusion] The balance training group using Nintendo Wii Fit Plus showed better results than the strengthening training group. Consequently, it is recommended to add the balance training program of the Nintendo Wii Fit Plus to conventional exercise programs to improve ankle muscle strength in functional ankle instability at a low cost. PMID:26696703

  9. Effects of Nintendo Wii Fit Plus training on ankle strength with functional ankle instability.

    PubMed

    Kim, Ki-Jong; Jun, Hyun-Ju; Heo, Myoung

    2015-11-01

    [Purpose] The objective of this study was to examine the effects of a training program using the Nintendo Wii Fit Plus on the ankle muscle strengths of subjects with functional ankle instability. [Subjects and Methods] This study was conducted using subjects in their 20s who had functional ankle instability. They were randomized to a strengthening training group and a balance training group with 10 subjects in each, and they performed an exercise using Nintendo Wii Fit Plus for 20 minutes. In addition, every participant completed preparation and finishing exercises for 5 minutes, respectively. [Results] The muscle strengths after conducting plantar flexion and dorsiflexion significantly increased at the angular velocities of 60° and 120° in the strengthening training group. Furthermore, the muscle strengths after conducting plantar flexion, dorsiflexion, eversion, and inversion significantly increased at the angular velocities of 60° and 120° in the balance training group. [Conclusion] The balance training group using Nintendo Wii Fit Plus showed better results than the strengthening training group. Consequently, it is recommended to add the balance training program of the Nintendo Wii Fit Plus to conventional exercise programs to improve ankle muscle strength in functional ankle instability at a low cost. PMID:26696703

  10. The pattern of excitation of human lower limb motoneurones by probable group II muscle afferents.

    PubMed

    Simonetta-Moreau, M; Marque, P; Marchand-Pauvert, V; Pierrot-Deseilligny, E

    1999-05-15

    1. Heteronymous group II effects were investigated in the human lower limb. Changes in firing probability of single motor units in quadriceps (Q), biceps (Bi), semitendinosus (ST), gastrocnemius medialis (GM) and tibialis anterior (TA) were studied after electrical stimuli between 1 and 3 times motor threshold (MT) applied to common peroneal (CP), superficial (SP) and deep (DP) peroneal, Bi and GM nerves in those nerve-muscle combinations without recurrent inhibition. 2. Stimulation of the CP and Bi nerves evoked in almost all of the explored Q motor units a biphasic excitation with a low-threshold early peak, attributable to non-monosynaptic group I excitation, and a higher threshold late peak. When the CP nerve was cooled (or the stimulation applied to a distal branch, DP), the increase in latency was greater for the late than for the early peak, indicating that the late excitation is due to stimulation of afferents with a slower conduction velocity than group I fibres, presumably in the group II range. In ST motor units the group II excitation elicited by stimulation of the GM and SP nerves was particularly large and frequent, and the non-monosynaptic group I excitation was often replaced by an inhibition. 3. A late group II-induced excitation from CP to Q motoneurones and from GM and SP to ST motoneurones was also observed when using the H reflex as a test. 4. The electrical threshold and conduction velocity of the largest diameter fibres evoking the group II excitation were estimated to be 2.1 and 0.65 times those of the fastest Ia afferents, respectively. In the combinations tested in the present investigation the group II input seemed to be primarily of muscle origin. 5. The potent heteronymous group II excitation of motoneurones of both flexors and extensors of the knee contrasted with the absence of a group II effect from DP to GM and from GM to TA. In none of the combinations explored was there any evidence for group II inhibition of motoneurones. The

  11. Trophism between C-type axon terminals and thoracic motoneurones in the cat

    PubMed Central

    Pullen, A. H.; Sears, T. A.

    1983-01-01

    1. Quantitative ultrastructural examinations of axon terminals synapsing with normal α-motoneurones in segment T9 of cat spinal cord provided estimates of their numbers, sizes and synaptic structure. One synapse, the C type, derived from short-axon propriospinal segmental interneurones, was studied in detail. 2. The numbers, sizes and post-synaptic structure of normal C-type synapses at T9 were compared with similar estimates from material provided by cats subjected to partial central deafferentation by double spinal hemisection at T5 and T10 between 7 days and 2 years previously. 3. The proportion of C-type synapses present progessively increased from 1% in normal cats to 8·8% 200 days following hemisection, and had still attained a level of 3·1% by 2 years; these increases imply that the absolute number of C-type synapses underwent increase. 4. Mean sizes of C-type synapses increased from 4·0 μm (normal) to 5·8 μm (200 days) and retained their enlarged sizes up to 2 years (5·9 μm). Furthermore, while 84% of C-type synapses were under 6 μm in length in normal motoneurones, 48% were over 6 μm long 200 days post-operatively. 5. The unique post-synaptic structure of C-type synapses also proliferated following partial central deafferentation of the motoneurones. The elongated cistern, increased numbers and individual lengths of lamellae of the associated underlying rough endoplasmic reticulum indicated a trophic interaction between the presynaptic C terminal and its post-synaptic motoneurone. 6. Counts of ribosomes `bound' to lamellae of the subsynaptic rough endoplasmic reticulum, and of the lamellae-associated polyribosomes interposed between individual lamellae for normal and 200 day post-operative C-type synapses indicated an over-all post-operative increase in capacity for local subsynaptic protein synthesis topographically directed towards this type of axon terminal. 7. The observed greater increase in frequency of ribosomes `bound' to the rough

  12. Modulation of ankle stiffness during postural sway.

    PubMed

    Lang, Christopher B; Kearney, Robert E

    2014-01-01

    Ankle stiffness is a nonlinear, time-varying system which contributes to the control of human upright stance. This study sought to examine the nature of the contribution of stiffness to postural control by determining how intrinsic and reflex stiffnesses varied with sway. Subjects were instructed to stand quietly on a bilateral electro-hydraulic actuator while perturbations were applied about the ankle. Subjects performed three types of trials: normal stance, forward lean, and backward lean. Position, torque, and EMGs from the tibialis anterior and triceps surae were recorded. Background torque, intrinsic stiffness and reflex stiffness were calculated for each perturbation. Intrinsic and reflex stiffnesses were heavily modulated by postural sway. Moreover, they were modulated in a complimentary manner; intrinsic stiffness was lowest when reflex gain was highest, and vice versa. These findings suggest that intrinsic stiffness is modulated simultaneously with reflex stiffness to optimize the control of balance. PMID:25570884

  13. Analgesia for people with acute ankle sprain.

    PubMed

    Carter, David; Amblum-Almer, Jeshni

    2015-04-01

    Around 302,000 people with soft-tissue ankle injuries present to UK emergency departments every year (Ferran and Maffulli 2006). These patients are generally treated conservatively with analgesia, ice, compression and elevation, and rest. There is some discussion in the literature about whether or not people with these injuries should be treated with non-steroidal anti-inflammatory drugs (NSAIDs), with some authors claiming that the inflammatory response following injury is part of the healing process and should not be halted. This article examines the literature on the efficacy of administering NSAIDs as the first-line drug management for ankle sprain. It also considers cost of treatment, prescribing practice and contraindications of NSAIDs. PMID:25854742

  14. Surgical treatment of ankle instability in athletes.

    PubMed Central

    Kristiansen, B.

    1982-01-01

    Eighteen athletes with symptoms of recurrent sprain and instability of the ankle during activity were treated by reconstructing the lateral ligament by the Evans technique. Before the operation 55 per cent had given up all athletic activities because of pain, swelling or instability, and 17 per cent had restricted their activities. The average age at operation was 24.6 years and the average follow-up period 3.1 years. Normal stability was achieved in 67 per cent and improved stability in 11 per cent, but only 33 per cent were still engaged in athletic activities without any complaints from the ankle. The results are similar to other methods of surgical repair. Images p40-a Fig. 2a Fig. 2b Fig. 3a Fig. 3b PMID:6802212

  15. Imaging in Foot and Ankle Arthritis.

    PubMed

    Wilkinson, Victoria H; Rowbotham, Emma L; Grainger, Andrew J

    2016-04-01

    The foot and ankle are commonly involved in a range of arthritides that affect the joints, bones, and soft tissues. Accurate plain film interpretation can often aid the diagnosis and monitor disease progression and treatment response. Ultrasound and MRI afford superior depiction of the soft tissues, and advances over recent years have centered on early detection of synovitis, enabling earlier diagnosis and treatment. Advantages and disadvantages of the imaging techniques of radiography, multidetector computed tomography, ultrasound, and MRI are discussed, as is optimization of these modalities for the assessment of the anatomically complex joints of the foot and ankle. Diagnostic features enabling differentiation between rheumatoid arthritis, seronegative spondyloarthropathies, osteoarthritis, gout, crystal deposition disease, pigmented villonodular synovitis, Charcot arthropathy, septic arthritis, synovial osteochondromatosis, hemophilia, and reflex sympathetic dystrophy are also reviewed. PMID:27336451

  16. Total ankle replacement. Early experiences with STAR prosthesis.

    PubMed Central

    Murnaghan, J. M.; Warnock, D. S.; Henderson, S. A.

    2005-01-01

    Early designs of Total Ankle Replacement (TAR) had a high failure rate. More recent experience with the 3-piece, meniscal bearing, total ankle replacement has been more promising. We report a review of the early results of our first 22 prostheses in 20 patients undergoing Scandinavian Total Ankle Replacement (STAR) in Northern Ireland. There was a mean follow-up time of 26 months. Seventeen patients are pain-free at the ankle joint during normal daily activities. Two of the early cases have required revision surgery due to technical errors. Other complications have included malleolar fractures, poor wound healing and postoperative stiffness. These early results show high levels of patient satisfaction, and we are encouraged to continue with total ankle arthroplasty. There is a steep initial learning curve and use of TAR should be restricted to foot and ankle surgeons. Images Fig 1 Figs 2a and b Figs 2 c and d PMID:16022128

  17. Total ankle replacement. Early experiences with STAR prosthesis.

    PubMed

    Murnaghan, J M; Warnock, D S; Henderson, S A

    2005-05-01

    Early designs of Total Ankle Replacement (TAR) had a high failure rate. More recent experience with the 3-piece, meniscal bearing, total ankle replacement has been more promising. We report a review of the early results of our first 22 prostheses in 20 patients undergoing Scandinavian Total Ankle Replacement (STAR) in Northern Ireland. There was a mean follow-up time of 26 months. Seventeen patients are pain-free at the ankle joint during normal daily activities. Two of the early cases have required revision surgery due to technical errors. Other complications have included malleolar fractures, poor wound healing and postoperative stiffness. These early results show high levels of patient satisfaction, and we are encouraged to continue with total ankle arthroplasty. There is a steep initial learning curve and use of TAR should be restricted to foot and ankle surgeons. PMID:16022128

  18. Biomechanical Evaluation of a Prototype Foot/Ankle Prosthesis

    PubMed Central

    Quesada, P. M.; Pitkin, M.; Colvin, J.

    2016-01-01

    In this paper, we report on our pilot evaluation of a prototype foot/ankle prosthesis. This prototype has been designed and fabricated with the intention of providing decreased ankle joint stiffness during the middle portion of the stance phase of gait, and increased (i.e., more normal) knee range of motion during stance. Our evaluation involved fitting the existing prototype foot/ankle prosthesis, as well as a traditional solid ankle cushioned heel (SACH) foot, to an otherwise healthy volunteer with a below-knee (BK) amputation. We measured this individual’s lower extremity joint kinematics and kinetics during walking using a video motion analysis system and force platform. These measurements permitted direct comparison of prosthetic ankle joint stiffness and involved side knee joint motion, as well as prosthetic ankle joint moment and power. PMID:10779119

  19. Neuromuscular control and rehabilitation of the unstable ankle

    PubMed Central

    Hung, You-jou

    2015-01-01

    Lateral ankle sprain is a common orthopedic injury with a very high recurrence rate in athletes. After decades of research, it is still unclear what contributes to the high recurrence rate of ankle sprain, and what is the most effective intervention to reduce the incident of initial and recurrent injuries. In addition, clinicians often implement balance training as part of the rehabilitation protocol in hopes of enhancing the neuromuscular control and proprioception of the ankle joint. However, there is no consensus on whether the neuromuscular control and proprioception are compromised in unstable ankles. To reduce the prevalence of ankle sprains, the effectiveness of engaging balance training to enhance the neuromuscular control and proprioception of the ankle joint is also questionable. PMID:26085985

  20. [Advances on biomechanics and kinematics of sprain of ankle joint].

    PubMed

    Zhao, Yong; Wang, Gang

    2015-04-01

    Ankle sprains are orthopedic clinical common disease, accounting for joint ligament sprain of the first place. If treatment is not timely or appropriate, the joint pain and instability maybe develop, and even bone arthritis maybe develop. The mechanism of injury of ankle joint, anatomical basis has been fully study at present, and the diagnostic problem is very clear. Along with the development of science and technology, biological modeling and three-dimensional finite element, three-dimensional motion capture system,digital technology study, electromyographic signal study were used for the basic research of sprain of ankle. Biomechanical and kinematic study of ankle sprain has received adequate attention, combined with the mechanism research of ankle sprain,and to explore the the biomechanics and kinematics research progress of the sprain of ankle joint. PMID:26072625

  1. Diagnostic dilemmas in foot and ankle injuries

    SciTech Connect

    Keene, J.S.; Lange, R.H.

    1986-07-11

    Differential diagnosis of foot and ankle injuries should include (1) stress fractures of the great toe sesamoids, the shaft of the fifth metatarsal, and the tarsal navicular bone; (2) transchondral talar-dome fractures; (3) fractures of the os trigonum; and (4) dislocating peroneal tendons. Diagnosis of these injuries is challenging because the initial roentgenograms often are normal, and special clinical tests and ancillary studies are required.

  2. Forces predicted at the ankle during running.

    PubMed

    Burdett, R G

    1982-01-01

    A biomechanical model of the ankle joint was developed and was used to predict the forces at the ankle during the stance phase of running. Measurements from five cadavers were averaged to obtain insertion points and directions of pull of equivalent tendons with respect to the assumed center of the ankle joint. A minimum joint force solution was obtained by assuming that only two equivalent muscle groups could exert force at one time. Three subjects ran at 4.47 m/s across a force platform that recorded the external forces and moments acting on the foot. Cinematography was used to measure the foot and leg positions during stance. Peak resultant joint forces ranging from 9.0 to 13.3 times body weight and peak Achilles tendon forces ranging from 5.3 to 10.0 times body weight were predicted. Small variations in some cases resulted in large differences in predicted forces. The highest tendon forces predicted exceeded those reported to cause damage to cadaver tendons in other studies. PMID:7132650

  3. Diagnosing syndesmotic instability in ankle fractures

    PubMed Central

    van den Bekerom, Michel PJ

    2011-01-01

    The precise diagnosis of distal tibiofibular syndesmotic ligament injury is challenging and a distinction should be made between syndesmotic ligament disruption and real syndesmotic instability. This article summarizes the available evidence in the light of the author’s opinion. Pre-operative radiographic assessment, standard radiographs, computed tomography scanning and magnetic resonance imaging are of limited value in detecting syndesmotic instability in acute ankle fractures but can be helpful in planning. Intra-operative stress testing, in the sagittal, coronal or exorotation direction, is more reliable in the diagnosis of syndesmotic instability of rotational ankle fractures. The Hook or Cotton test is more reliable than the exorotation stress test. The lateral view is more reliable than the AP mortise view because of the larger displacement in this direction. When the Hook test is used the force should be applied in the sagittal direction. A force of 100 N applied to the fibula seems to be appropriate. In the case of an unstable joint requiring syndesmotic stabilisation, the tibiofibular clear space would exceed 5 mm on the lateral stress test. When the surgeon is able to perform an ankle arthroscopy this technique is useful to detect syndesmotic injury and can guide anatomic reduction of the syndesmosis. Many guidelines formulated in this article are based on biomechanical and cadaveric studies and clinical correlation has to be established. PMID:22474636

  4. Rheumatoid Arthritis of the Foot and Ankle.

    PubMed

    Abdo; Iorio

    1994-11-01

    Rheumatoid arthritis of the foot and ankle can be a debilitating problem, particularly for patients who have undergone successful hip or knee arthroplasty. Optimal medical management, use of orthotic devices, and surgical intervention are essential components of patient care. Forefoot involvement with hallux valgus and lesser metatarsophalangeal joint subluxation and dislocation are the most common findings. Reconstruction usually requires lesser metatarsophalangeal joint excisional arthroplasty and first metatarsophalangeal joint arthrodesis. Midfoot tarsometatarsal and intertarsal involvement is treated with orthotic devices and intertarsal fusion for advanced arthropathy. Hindfoot involvement frequently leads to pes planovalgus deformity, which may require isolated talonavicular arthrodesis if treated early or triple arthrodesis for advanced destruction. Ankle involvement is less frequent; when it is unresponsive to conservative measures, ankle symptoms may be improved by arthrodesis. Although great advances have been made in medical and surgical management of rheumatoid arthritis, the disease remains a serious problem. Through prudent use of medical management, orthotic devices, and other conservative measures as well as surgical intervention, long-term function can be enhanced greatly. PMID:10709025

  5. Rehabilitation of Ankle and Foot Injuries in Athletes

    PubMed Central

    Chinn, Lisa; Hertel, Jay

    2009-01-01

    Foot and ankle injuries are extremely common among athletes and other physically active individuals. Rehabilitation programs that emphasize the use of therapeutic exercise to restore joint range of motion, muscle strength, neuromuscular coordination, and gait mechanics have been shown to have clinical success for patients suffering various foot and ankle pathologies. Rehabilitation programs are discussed for ankle sprains, plantar fasciitis, Achilles tendonitis, and turf toe. PMID:19945591

  6. Reconstructive Osteotomy for Ankle Malunion Improves Patient Satisfaction and Function

    PubMed Central

    Tohyama, Masahiko; Yasuda, Hiroyuki; Konishi, Sadahiko; Waseda, Akeo

    2015-01-01

    Treatment of chronic symptoms caused by a malunion is a difficult problem in orthopedic surgery. We encountered a case of ankle malunion at our hospital about 1 year after the first operation. The patient had been unable to walk with weight-bearing but regained the ability to walk after reconstructive osteotomy of the fibula. Functional scores for the foot and ankle were significantly improved after intervention. Reconstructive osteotomy appears to represent a good option for ankle malunion. PMID:26064743

  7. Developing a Framework for Ankle Function: A Delphi Study

    PubMed Central

    Snyder, Kelli R.; Evans, Todd A.; Neibert, Peter J.

    2014-01-01

    Context: Addressing clinical outcomes is paramount to providing effective health care, yet there is no consensus regarding the appropriate outcomes to address after ankle injuries. Compounding the problem is the repetitive nature of lateral ankle sprains, referred to as functional (FAI) or chronic (CAI) ankle instability. Although they are commonly used terms in practice and research, FAI and CAI are inconsistently defined and assessed. Objective: To establish definitions of a healthy/normal/noninjured ankle, FAI, and CAI, as well as their characteristics and assessment techniques. Design: Delphi study. Setting: Telephone interviews and electronic surveys. Patients or Other Participants: Sixteen experts representing the fields of ankle function and treatment, ankle research, and outcomes assessment and research were selected as panelists. Data Collection and Analysis: A telephone interview produced feedback regarding the definition of, functional characteristics of, and assessment techniques for a healthy/normal/noninjured ankle, an unhealthy/acutely injured ankle, and FAI/CAI. Those data were compiled, reduced, and returned through electronic surveys and were either included by reaching consensus (80% agreement) or excluded. Results: The definitions of a healthy/normal/noninjured ankle and FAI reached consensus. Experts did not agree on a definition of CAI. Eleven functional characteristics of a healthy/normal/noninjured ankle, 32 functional characteristics of an unhealthy/acutely injured ankle, and 13 characteristics of FAI were agreed upon. Conclusions: Although a consensus was reached regarding the definitions and functional characteristics of a healthy/normal/noninjured ankle and FAI, the experts could only agree on 1 characteristic to include in the FAI definition. Several experts did, however, provide additional comments that reinforced the differences in the interpretation of those concepts. Although the experts could not agree on the definition of CAI, its

  8. MRI in acute ligamentous injuries of the ankle.

    PubMed

    Martella, Ilenia; Azzali, Emanuele; Milanese, Gianluca; Praticò, Francesco Emanuele; Ruggirello, Margherita; Trunfio, Vincenzo; Parziale, Raffaele; Corrado, Michele; Della Casa, Giovanni; Capasso, Raffaella; De Filippo, Massimo

    2016-01-01

    Ankle sprains are the most common lower limb injuries and affect more frequently young athletes; imaging is needed for an accurate diagnosis of such traumatic injuries. The purpose of this review is to analyse the magnetic resonance (MR) findings of both normal and pathological ankle's ligaments; indeed, MRI is the gold standard for the diagnosis of acute traumatic injuries and is useful for differentiation of the causes of ankle instability as well as for pre-operative planning. PMID:27467862

  9. Electrophysiological properties of lumbar motoneurons in the alpha-chloralose-anesthetized cat during carbachol-induced motor inhibition.

    PubMed

    Xi, M C; Liu, R H; Yamuy, J; Morales, F R; Chase, M H

    1997-07-01

    The present study was undertaken 1) to examine the neuronal mechanisms responsible for the inhibition of spinal cord motoneurons that occurs in alpha-chloralose-anesthetized cats following the microinjection of carbachol into the nucleus pontis oralis (NPO), and 2) to determine whether the inhibitory mechanisms are the same as those that are responsible for the postsynaptic inhibition of motoneurons that is present during naturally occurring active sleep. Accordingly, the basic electrophysiological properties of lumbar motoneurons were examined, with the use of intracellular recording techniques, in cats anesthetized with alpha-chloralose and compared with those present during naturally occurring active sleep. The intrapontine administration of carbachol resulted in a sustained reduction in the amplitude of the spinal cord Ia monosynaptic reflex. Discrete large-amplitude inhibitory postsynaptic potentials (IPSPs), which are only present during the state of active sleep in the chronic cat, were also observed in high-gain recordings from lumbar motoneurons after the injection of carbachol. During carbachol-induced motor inhibition, lumbar motoneurons exhibited a statistically significant decrease in input resistance, membrane time constant and a reduction in the amplitude of the action potential's afterhyperpolarization. In addition, there was a statistically significant increase in rheobase and in the delay between the initial-segment (IS) and somadendritic (SD) portions of the action potential (IS-SD delay). There was a significant increase in the mean motoneuron resting membrane potential (i.e., hyperpolarization). The preceding changes in the electrophysiological properties of motoneurons, as well as the development of discrete IPSPs, indicate that lumbar motoneurons are postsynaptically inhibited after the intrapontine administration of carbachol in cats that are anesthetized with alpha-chloralose. These changes in the electrophysiological properties of lumbar

  10. Repeated stimuli for axonal growth causes motoneuron death in adult rats: the effect of botulinum toxin followed by partial denervation.

    PubMed

    White, C M; Greensmith, L; Vrbová, G

    2000-01-01

    Axons of motoneurons to tibialis anterior and extensor digitorum longus muscles of adult rats were induced to sprout by injecting botulinum toxin into them, by partial denervation or by a combination of the two procedures. Ten weeks later, the number of motoneurons innervating the control and operated tibialis anterior and extensor digitorum longus muscles was established by retrograde labelling with horseradish peroxidase. In the same preparations, the motoneurons were also stained with a Nissl stain (gallocyanin) to reveal motoneurons in the sciatic pool. Examination of the spinal cords from animals treated with botulinum toxin showed that the number of retrogradely labelled cells and those stained with gallocyanin in the ventral horn on the treated compared to the control side was unchanged. In rats that had their L4 spinal nerve sectioned on one side, the number of retrogradely labelled cells on the operated side was 48+/-3% (n = 5) of that present in the control unoperated ventral horn. Thus, just over half the innervation was removed by cutting the L4 spinal nerve. Counts made from gallocyanin-stained sections showed that 94+/-4% (n = 5) of motoneurons were present in the ventral horn on the operated side. Thus, section of the L4 spinal nerve did not lead to any death of motoneurons. In rats that had their muscles injected with botulinum toxin three weeks prior to partial denervation, the number of retrogradely labelled cells was reduced from 48+/-3% (n = 5) to 35+/-4% (n = 5). Moreover, only 67+/-5% (n = 5) of motoneurons stained with gallocyanin, suggesting that a proportion of motoneurons died after this combined procedure. This result was supported by experiments in which motor unit numbers in extensor digitorum longus muscles were determined by measurements of stepwise increments of force in response to stimulation of the motor nerve with increasing stimulus intensity. In partially denervated extensor digitorum longus muscles, 16.6+/-0.7 (n = 5) motor

  11. [Measurement ofthe ankle-brachial pressure index (ABPI)].

    PubMed

    Kulisić, Sandra Marinović

    2012-10-01

    Measurement of the ankle-brachial pressure index, also known as ankle-brachial index or ankle-arm index is a ratio of the ankle blood pressure and brachial blood pressure. It is easy to perform and allows for diagnosis and further definition of the severity of peripheral arterial disease with sensitivity 90% and specificity 98%. The test is not appropriate for mild arterial changes as in case of comorbidity. Its further objectives are to identify patients at an higher risk of cardiovascular events. PMID:23193828

  12. Increased incidence of gap junctional coupling between spinal motoneurones following transient blockade of NMDA receptors in neonatal rats

    PubMed Central

    Mentis, George Z; Díaz, Eugenia; Moran, Linda B; Navarrete, Roberto

    2002-01-01

    Neonatal rat motoneurones are electrically coupled via gap junctions and the incidence of this coupling declines during postnatal development. The mechanisms involved in this developmental regulation of gap junctional communication are largely unknown. Here we have studied the role of NMDA receptor-mediated glutamatergic synaptic activity in the regulation of motoneurone coupling. Gap junctional coupling was demonstrated by the presence of graded, short latency depolarising potentials following ventral root stimulation, and by the transfer of the low molecular weight tracer Neurobiotin to neighbouring motoneurones. Sites of close apposition between the somata and/or dendrites of the dye-coupled motoneurones were identified as potential sites of gap junctional coupling. Early postnatal blockade of the NMDA subtype of glutamate receptors using the non-competitive antagonist dizocilpine maleate (MK801) arrested the developmental decrease in electrotonic and dye coupling during the first postnatal week. These results suggest that the postnatal increase in glutamatergic synaptic activity associated with the onset of locomotion promote the loss of gap junctional connections between developing motoneurones. PMID:12411521

  13. Role of HSP70 in motoneuron survival after excitotoxic stress in a rat spinal cord injury model in vitro.

    PubMed

    Shabbir, Ayisha; Bianchetti, Elena; Cargonja, Renato; Petrovic, Antonela; Mladinic, Miranda; Pilipović, Kristina; Nistri, Andrea

    2015-12-01

    The outcome for gait recovery from paralysis due to spinal lesion remains uncertain even when damage is limited. One critical factor is the survival of motoneurons, which are very vulnerable cells. To clarify the early pathophysiological mechanisms of spinal damage, an in vitro injury model of the rat spinal cord caused by moderate excitotoxicity was used. With this preparation we investigated whether motoneuron survival was dependent on the expression of the neuroprotective protein HSP70. In the present study excitotoxicity evoked by kainate induced delayed (24 h) loss (35%) of motoneurons, which became pyknotic with translocation of the cell death biomarker apoptosis-inducing factor (AIF) to the nucleus. This process was concomitant with suppression of locomotor network electrical activity. Surviving cells showed strong expression of HSP70 without nuclear AIF. The HSP70 inhibitor VER155008 per se induced neurotoxicity similar to that of kainate, while the HSP90 inhibitor geldanamycin did not damage spinal tissue. Electrophysiological recording following kainate or VER155008 indicated depression of motoneuron field potentials, with decreased excitability and impaired synaptic transmission. When these two drugs were applied together, more intense neurotoxicity emerged. Our data indicate that HSP70 was one important contributor to motoneuron survival and suggest that enhancing HSP70 activity is a potential future strategy for neuroprotecting these cells. PMID:26490753

  14. Association of Diabetes and Hemodialysis With Ankle Pressure and Ankle-Brachial Index in Japanese Patients With Critical Limb Ischemia

    PubMed Central

    Takahara, Mitsuyoshi; Kaneto, Hideaki; Iida, Osamu; Katakami, Naoto; Matsuoka, Taka-aki; Ikeda, Masahiko; Shimomura, Iichiro

    2012-01-01

    OBJECTIVE To investigate whether diabetes and regular hemodialysis are associated with false elevation of ankle systolic blood pressure and ankle-brachial systolic pressure index (ABI) because of their arterial calcification in patients with critical limb ischemia (CLI). RESEARCH DESIGN AND METHODS We recruited 269 Japanese patients who underwent endovascular therapy for CLI. Ankle systolic blood pressure and ABI were assessed before endovascular therapy. Arterial stenosis and calcification were evaluated angiographically. We investigated the associations among clinical comorbidities, arterial calcification, and measurements of ankle systolic blood pressure and ABI. RESULTS Ankle systolic blood pressure was 85 ± 56 mmHg, and ABI was 0.59 ± 0.37. Arterial calcification was observed in 69% of the patients. The prevalence of diabetes and regular hemodialysis was 71 and 47%. Diabetes and regular hemodialysis were both significantly associated with the presence of arterial calcification; their adjusted odds ratios were 2.33 (P = 0.01) and 7.40 (P < 0.01), respectively. However, there was no significant difference in ankle systolic blood pressure or ABI level between those with and without these comorbidities. Furthermore, the presence of arterial calcification was not associated with ankle systolic blood pressure or ABI level, whereas arterial stenoses of all segments in the lower body had independent associations with reduced ankle systolic blood pressure and ABI level. CONCLUSIONS Diabetes and regular hemodialysis were significantly associated with arterial calcification, but not with elevated measurements of ankle systolic blood pressure or ABI, in CLI patients. PMID:22723344

  15. Ultrasonography in the Assessment of Lateral Ankle Ligament Injury, Instability, and Anterior Ankle Impingement: A Diagnostic Case Report

    PubMed Central

    Battaglia, Patrick J.; Craig, Kate; Kettner, Norman W.

    2015-01-01

    Objective The purpose of this case report is to describe the diagnostic value of ultrasonography (US) in a patient with injury to the lateral ligaments of the ankle with concomitant ankle joint osteoarthritis and anterior impingement. Clinical Features A 28-year-old male had a history of an inversion injury of the left ankle. Diagnostic US of the left ankle using an 8- to 15-MHz linear array transducer demonstrated a full thickness tear of the anterior talofibular ligament, partial thickness tearing of the calcaneofibular ligament, and laxity of the ankle with varus stress testing. In addition, US was able to demonstrate degeneration of the ankle and talonavicular joints and anterior impingement with dorsiflexion. Osteoarthritic changes were confirmed with radiography. Other US findings included remote deltoid ligamentous complex injury, multiple sites of tenosynovitis, and a large ankle joint effusion with synovial hypertrophy and synovitis. Intervention and Outcome Using US, an accurate diagnosis was established with respect to the pathology and functional impairments of the patient’s ankle. Conclusion This case report exemplifies the value and utility of US in diagnosing derangement in ligamentous, tendinous, articular, and osseous injuries of the ankle. PMID:26793038

  16. Joint Stability Characteristics of the Ankle Complex in Female Athletes With Histories of Lateral Ankle Sprain, Part II: Clinical Experience Using Arthrometric Measurement

    PubMed Central

    Kovaleski, John E.; Heitman, Robert J.; Gurchiek, Larry R.; Hollis, J. M.; Liu, Wei; IV, Albert W. Pearsall

    2014-01-01

    Context: This is part II of a 2-part series discussing stability characteristics of the ankle complex. In part I, we used a cadaver model to examine the effects of sectioning the lateral ankle ligaments on anterior and inversion motion and stiffness of the ankle complex. In part II, we wanted to build on and apply these findings to the clinical assessment of ankle-complex motion and stiffness in a group of athletes with a history of unilateral ankle sprain. Objective: To examine ankle-complex motion and stiffness in a group of athletes with reported history of lateral ankle sprain. Design: Cross-sectional study. Setting: University research laboratory. Patients or Other Participants: Twenty-five female college athletes (age = 19.4 ± 1.4 years, height = 170.2 ± 7.4 cm, mass = 67.3 ± 10.0 kg) with histories of unilateral ankle sprain. Intervention(s): All ankles underwent loading with an ankle arthrometer. Ankles were tested bilaterally. Main Outcome Measure(s): The dependent variables were anterior displacement, anterior end-range stiffness, inversion rotation, and inversion end-range stiffness. Results: Anterior displacement of the ankle complex did not differ between the uninjured and sprained ankles (P = .37), whereas ankle-complex rotation was greater for the sprained ankles (P = .03). The sprained ankles had less anterior and inversion end-range stiffness than the uninjured ankles (P < .01). Conclusions: Changes in ankle-complex laxity and end-range stiffness were detected in ankles with histories of sprain. These results indicate the presence of altered mechanical characteristics in the soft tissues of the sprained ankles. PMID:24568223

  17. Revisiting Antagonist Effects in Hypoglossal Nucleus: Brainstem Circuit for the State-Dependent Control of Hypoglossal Motoneurons: A Hypothesis

    PubMed Central

    Fenik, Victor B.

    2015-01-01

    We reassessed and provided new insights into the findings that were obtained in our previous experiments that employed the injections of combined adrenergic, serotonergic, GABAergic, and glycinergic antagonists into the hypoglossal nucleus in order to pharmacologically abolish the depression of hypoglossal nerve activity that occurred during carbachol-induced rapid-eye-movement (REM) sleep-like state in anesthetized rats. We concluded that noradrenergic disfacilitation is the major mechanism that is responsible for approximately 90% of the depression of hypoglossal motoneurons, whereas the remaining 10% can be explained by serotonergic mechanisms that have net inhibitory effect on hypoglossal nerve activity during REM sleep-like state. We hypothesized that both noradrenergic and serotonergic state-dependent mechanisms indirectly control hypoglossal motoneuron excitability during REM sleep; their activities are integrated and mediated to hypoglossal motoneurons by reticular formation neurons. In addition, we proposed a brainstem neural circuit that can explain the new findings. PMID:26648908

  18. Proper migration and axon outgrowth of zebrafish cranial motoneuron subpopulations require the cell adhesion molecule MDGA2A

    PubMed Central

    Ingold, Esther; vom Berg-Maurer, Colette M.; Burckhardt, Christoph J.; Lehnherr, André; Rieder, Philip; Keller, Philip J.; Stelzer, Ernst H.; Greber, Urs F.; Neuhauss, Stephan C. F.; Gesemann, Matthias

    2015-01-01

    ABSTRACT The formation of functional neuronal circuits relies on accurate migration and proper axonal outgrowth of neuronal precursors. On the route to their targets migrating cells and growing axons depend on both, directional information from neurotropic cues and adhesive interactions mediated via extracellular matrix molecules or neighbouring cells. The inactivation of guidance cues or the interference with cell adhesion can cause severe defects in neuronal migration and axon guidance. In this study we have analyzed the function of the MAM domain containing glycosylphosphatidylinositol anchor 2A (MDGA2A) protein in zebrafish cranial motoneuron development. MDGA2A is prominently expressed in distinct clusters of cranial motoneurons, especially in the ones of the trigeminal and facial nerves. Analyses of MDGA2A knockdown embryos by light sheet and confocal microscopy revealed impaired migration and aberrant axonal outgrowth of these neurons; suggesting that adhesive interactions mediated by MDGA2A are required for the proper arrangement and outgrowth of cranial motoneuron subtypes. PMID:25572423

  19. Astrocytes expressing mutant SOD1 and TDP43 trigger motoneuron death that is mediated via sodium channels and nitroxidative stress

    PubMed Central

    Rojas, Fabiola; Cortes, Nicole; Abarzua, Sebastian; Dyrda, Agnieszka; van Zundert, Brigitte

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal paralytic disorder caused by dysfunction and degeneration of motor neurons. Multiple disease-causing mutations, including in the genes for SOD1 and TDP-43, have been identified in ALS. Astrocytes expressing mutant SOD1 are strongly implicated in the pathogenesis of ALS: we have shown that media conditioned by astrocytes carrying mutant SOD1G93A contains toxic factor(s) that kill motoneurons by activating voltage-sensitive sodium (Nav) channels. In contrast, a recent study suggests that astrocytes expressing mutated TDP43 contribute to ALS pathology, but do so via cell-autonomous processes and lack non-cell-autonomous toxicity. Here we investigate whether astrocytes that express diverse ALS-causing mutations release toxic factor(s) that induce motoneuron death, and if so, whether they do so via a common pathogenic pathway. We exposed primary cultures of wild-type spinal cord cells to conditioned medium derived from astrocytes (ACM) that express SOD1 (ACM-SOD1G93A and ACM-SOD1G86R) or TDP43 (ACM-TDP43A315T) mutants; we show that such exposure rapidly (within 30–60 min) increases dichlorofluorescein (DCF) fluorescence (indicative of nitroxidative stress) and leads to extensive motoneuron-specific death within a few days. Co-application of the diverse ACMs with anti-oxidants Trolox or esculetin (but not with resveratrol) strongly improves motoneuron survival. We also find that co-incubation of the cultures in the ACMs with Nav channel blockers (including mexiletine, spermidine, or riluzole) prevents both intracellular nitroxidative stress and motoneuron death. Together, our data document that two completely unrelated ALS models lead to the death of motoneuron via non-cell-autonomous processes, and show that astrocytes expressing mutations in SOD1 and TDP43 trigger such cell death through a common pathogenic pathway that involves nitroxidative stress, induced at least in part by Nav channel activity. PMID:24570655

  20. Motoneuronal and muscle synergies involved in cat hindlimb control during fictive and real locomotion: a comparison study.

    PubMed

    Markin, Sergey N; Lemay, Michel A; Prilutsky, Boris I; Rybak, Ilya A

    2012-04-01

    We compared the activity profiles and synergies of spinal motoneurons recorded during fictive locomotion evoked in immobilized decerebrate cat preparations by midbrain stimulation to the activity profiles and synergies of the corresponding hindlimb muscles obtained during forward level walking in cats. The fictive locomotion data were collected in the Spinal Cord Research Centre, University of Manitoba, and provided by Dr. David McCrea; the real locomotion data were obtained in the laboratories of M. A. Lemay and B. I. Prilutsky. Scatterplot representation and minimum spanning tree clustering algorithm were used to identify the possible motoneuronal and muscle synergies operating during both fictive and real locomotion. We found a close similarity between the activity profiles and synergies of motoneurons innervating one-joint muscles during fictive locomotion and the profiles and synergies of the corresponding muscles during real locomotion. However, the activity patterns of proximal nerves controlling two-joint muscles, such as posterior biceps and semitendinosus (PBSt) and rectus femoris (RF), were not uniform in fictive locomotion preparations and differed from the activity profiles of the corresponding two-joint muscles recorded during forward level walking. Moreover, the activity profiles of these nerves and the corresponding muscles were unique and could not be included in the synergies identified in fictive and real locomotion. We suggest that afferent feedback is involved in the regulation of locomotion via motoneuronal synergies controlled by the spinal central pattern generator (CPG) but may also directly affect the activity of motoneuronal pools serving two-joint muscles (e.g., PBSt and RF). These findings provide important insights into the organization of the spinal CPG in mammals, the motoneuronal and muscle synergies engaged during locomotion, and their afferent control. PMID:22190626

  1. Motoneuronal and muscle synergies involved in cat hindlimb control during fictive and real locomotion: a comparison study

    PubMed Central

    Markin, Sergey N.; Lemay, Michel A.; Prilutsky, Boris I.

    2012-01-01

    We compared the activity profiles and synergies of spinal motoneurons recorded during fictive locomotion evoked in immobilized decerebrate cat preparations by midbrain stimulation to the activity profiles and synergies of the corresponding hindlimb muscles obtained during forward level walking in cats. The fictive locomotion data were collected in the Spinal Cord Research Centre, University of Manitoba, and provided by Dr. David McCrea; the real locomotion data were obtained in the laboratories of M. A. Lemay and B. I. Prilutsky. Scatterplot representation and minimum spanning tree clustering algorithm were used to identify the possible motoneuronal and muscle synergies operating during both fictive and real locomotion. We found a close similarity between the activity profiles and synergies of motoneurons innervating one-joint muscles during fictive locomotion and the profiles and synergies of the corresponding muscles during real locomotion. However, the activity patterns of proximal nerves controlling two-joint muscles, such as posterior biceps and semitendinosus (PBSt) and rectus femoris (RF), were not uniform in fictive locomotion preparations and differed from the activity profiles of the corresponding two-joint muscles recorded during forward level walking. Moreover, the activity profiles of these nerves and the corresponding muscles were unique and could not be included in the synergies identified in fictive and real locomotion. We suggest that afferent feedback is involved in the regulation of locomotion via motoneuronal synergies controlled by the spinal central pattern generator (CPG) but may also directly affect the activity of motoneuronal pools serving two-joint muscles (e.g., PBSt and RF). These findings provide important insights into the organization of the spinal CPG in mammals, the motoneuronal and muscle synergies engaged during locomotion, and their afferent control. PMID:22190626

  2. Motoneuron properties during motor inhibition produced by microinjection of carbachol into the pontine reticular formation of the decerebrate cat.

    PubMed

    Morales, F R; Engelhardt, J K; Soja, P J; Pereda, A E; Chase, M H

    1987-04-01

    It is well established that cholinergic agonists, when injected into the pontine reticular formation in cats, produce a generalized suppression of motor activity (1, 3, 6, 14, 18, 27, 33, 50). The responsible neuronal mechanisms were explored by measuring ventral root activity, the amplitude of the Ia-monosynaptic reflex, and the basic electrophysiological properties of hindlimb motoneurons before and after carbachol was microinjected into the pontine reticular formation of decerebrate cats. Intrapontine microinjections of carbachol (0.25-1.0 microliter, 16 mg/ml) resulted in the tonic suppression of ventral root activity and a decrease in the amplitude of the Ia-monosynaptic reflex. An analysis of intracellular records from lumbar motoneurons during the suppression of motor activity induced by carbachol revealed a considerable decrease in input resistance and membrane time constant as well as a reduction in motoneuron excitability, as evidenced by a nearly twofold increase in rheobase. Discrete inhibitory postsynaptic potentials were also observed following carbachol administration. The changes in motoneuron properties (rheobase, input resistance, and membrane time constant), as well as the development of discrete inhibitory postsynaptic potentials, indicate that spinal cord motoneurons were postsynaptically inhibited following the pontine administration of carbachol. In addition, the inhibitory processes that arose after carbachol administration in the decerebrate cat were remarkably similar to those that are present during active sleep in the chronic cat. These findings suggest that the microinjection of carbachol into the pontine reticular formation activates the same brain stem-spinal cord system that is responsible for the postsynaptic inhibition of alpha-motoneurons that occurs during active sleep. PMID:3585456

  3. Comparison of dendritic calcium transients in juvenile wild type and SOD1(G93A) mouse lumbar motoneurons.

    PubMed

    Quinlan, Katharina A; Lamano, Jonathan B; Samuels, Julienne; Heckman, C J

    2015-01-01

    Previous studies of spinal motoneurons in the SOD1 mouse model of amyotrophic lateral sclerosis have shown alterations long before disease onset, including increased dendritic branching, increased persistent Na(+) and Ca(2+) currents, and impaired axonal transport. In this study dendritic Ca(2+) entry was investigated using two photon excitation fluorescence microscopy and whole-cell patch-clamp of juvenile (P4-11) motoneurons. Neurons were filled with both Ca(2+) Green-1 and Texas Red dextrans, and line scans performed throughout. Steps were taken to account for different sources of variability, including (1) dye filling and laser penetration, (2) dendritic anatomy, and (3) the time elapsed from the start of recording. First, Ca(2+) Green-1 fluorescence was normalized by Texas Red; next, neurons were reconstructed so anatomy could be evaluated; finally, time was recorded. Customized software detected the largest Ca(2+) transients (area under the curve) from each line scan and matched it with parameters above. Overall, larger dendritic diameter and shorter path distance from the soma were significant predictors of larger transients, while time was not significant up to 2 h (data thereafter was dropped). However, Ca(2+) transients showed additional variability. Controlling for previous factors, significant variation was found between Ca(2+) signals from different processes of the same neuron in 3/7 neurons. This could reflect differential expression of Ca(2+) channels, local neuromodulation or other variations. Finally, Ca(2+) transients in SOD1(G93A) motoneurons were significantly smaller than in non-transgenic motoneurons. In conclusion, motoneuron processes show highly variable Ca(2+) transients, but these transients are smaller overall in SOD1(G93A) motoneurons. PMID:25914627

  4. The effect of altered peripheral field on motoneurone function in developing rat soleus muscles.

    PubMed Central

    Lowrie, M B; O'Brien, R A; Vrbová, G

    1985-01-01

    In soleus muscles of 4- to 5-day-old rats the quantum content of axon terminals from L4 spinal roots is less than half that from L5. With development the size of L4 motor units decreases and the quantum content of L4 nerves increases to become similar to that of L5 axons. During this time the overlap of territories of L4 and L5 axons is reduced from 46% at 4-6 days to 2% at 18-20 days. This reduction occurs entirely at the expense of L4 territory. Removal of the L5 ventral ramus (v.r.) at 4-6 days prevents the reduction of L4 territory so that at 18 days L4 motor units are about 4 X normal size. In spite of this enlarged peripheral field of L4 axons the quantum content of their terminals increases to normal levels. When L5 v.r. was removed at 16-18 days, i.e. when the reduction of the L4 peripheral field was complete, expansion of L4 motor units was also seen, but in this case the quantum content of L4 terminals was less than normal. Thus it appears that during early stages of development, before synaptic reorganization within the muscle is complete, motoneurones are able to adapt their function to increased peripheral demands more effectively than at later stages of post-natal development. Retrograde labelling of soleus motor pool with horseradish peroxidase (HRP) showed that removal of L5 v.r. either at 4 or 15 days of age reduced the number of motoneurones supplying soleus muscle to less than 20%. No change in size of the remaining motoneurones was seen, indicating that the adjustment of transmitter output at the neuromuscular junctions in the younger group had no effect on the size of the cell. PMID:2867219

  5. Redistribution of Kv2.1 ion channels on spinal motoneurons following peripheral nerve injury.

    PubMed

    Romer, Shannon H; Dominguez, Kathleen M; Gelpi, Marc W; Deardorff, Adam S; Tracy, Robert C; Fyffe, Robert E W

    2014-02-14

    Pathophysiological responses to peripheral nerve injury include alterations in the activity, intrinsic membrane properties and excitability of spinal neurons. The intrinsic excitability of α-motoneurons is controlled in part by the expression, regulation, and distribution of membrane-bound ion channels. Ion channels, such as Kv2.1 and SK, which underlie delayed rectifier potassium currents and afterhyperpolarization respectively, are localized in high-density clusters at specific postsynaptic sites (Deardorff et al., 2013; Muennich and Fyffe, 2004). Previous work has indicated that Kv2.1 channel clustering and kinetics are regulated by a variety of stimuli including ischemia, hypoxia, neuromodulator action and increased activity. Regulation occurs via channel dephosphorylation leading to both declustering and alterations in channel kinetics, thus normalizing activity (Misonou et al., 2004; Misonou et al., 2005; Misonou et al., 2008; Mohapatra et al., 2009; Park et al., 2006). Here we demonstrate using immunohistochemistry that peripheral nerve injury is also sufficient to alter the surface distribution of Kv2.1 channels on motoneurons. The dynamic changes in channel localization include a rapid progressive decline in cluster size, beginning immediately after axotomy, and reaching maximum within one week. With reinnervation, the organization and size of Kv2.1 clusters do not fully recover. However, in the absence of reinnervation Kv2.1 cluster sizes fully recover. Moreover, unilateral peripheral nerve injury evokes parallel, but smaller effects bilaterally. These results suggest that homeostatic regulation of motoneuron Kv2.1 membrane distribution after axon injury is largely independent of axon reinnervation. PMID:24355600

  6. Motoneuron axon pathfinding errors in zebrafish: differential effects related to concentration and timing of nicotine exposure.

    PubMed

    Menelaou, Evdokia; Paul, Latoya T; Perera, Surangi N; Svoboda, Kurt R

    2015-04-01

    Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMNs). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15-30 μM). Previous work showed that the paralytic mutant zebrafish known as sofa potato exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at different developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window. PMID:25668718

  7. Antagonism of mGlu receptors and potentiation of EPSCs at rat spinal motoneurones in vitro.

    PubMed

    Cao, C Q; Tse, H W; Jane, D E; Evans, R H; Headley, P M

    1997-03-01

    The patch-clamp technique has been used to record synaptic responses, elicited by electrical stimulation of dorsal roots, in 28 single motoneurones of in vitro spinal cord preparations from neonate (P5 to P8) rats. The effects of (RS)-alpha-methyl-4-phosphonophenylglycine (MPPG) (200 microM), a potent antagonist at L-2-amino-4-phosphonobutanoate (AP4)-sensitive receptors, and (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG) (500 microM), which is a less selective antagonist of mGluRs, were tested on EPSCs alone and as antagonists of AP4-induced depression of EPSCs. The EC50 for depression of EPSCs by AP4 (1.16 +/- 0.12 microM, n = 8) was increased to 18.9 +/- 0.7 microM (n = 6) by MPPG. MCPG (500 microM) had no significant effect on the depressant potency of AP4. Under control conditions, EPSCs had mean peak amplitudes of 983 pA +/- 64 SEM and mean charge transferred of 306 +/- 37 pC (n = 28). These values were increased significantly (p < 0.05) to 1168 +/- 68 pA and 363 +/- 39 pC by MPPG (n = 6), and 1150 +/- 54 pA and 358 +/- 33 pC (n = 6) by MCPG. There was no significant difference between the enhancement of the initial peak of the EPSCs (mean latency from stimulus artifact 5.9 +/- 0.3 ms) and later components, suggesting mGluRs to be present on primary afferent terminals presynaptic to motoneurones as well as in pathways via interneurones. These results are consistent with the presence of at least two types of presynaptic mGluR that modulate release of glutamate in segmental pathways convergent onto motoneurones. These receptors appear to be activated by interstitial glutamate tonically present in the present preparations. PMID:9175609

  8. Persistent GABAA/C responses to gabazine, taurine and beta-alanine in rat hypoglossal motoneurons.

    PubMed

    Chesnoy-Marchais, D

    2016-08-25

    In hypoglossal motoneurons, a sustained anionic current, sensitive to a blocker of ρ-containing GABA receptors, (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA) and insensitive to bicuculline, was previously shown to be activated by gabazine. In order to better characterize the receptors involved, the sensitivity of this atypical response to pentobarbital (30μM), allopregnanolone (0.3μM) and midazolam (0.5μM) was first investigated. Pentobarbital potentiated the response, whereas the steroid and the benzodiazepine were ineffective. The results indicate the involvement of hybrid heteromeric receptors, including at least a GABA receptor ρ subunit and a γ subunit, accounting for the pentobarbital-sensitivity. The effects of the endogenous β amino acids, taurine and β-alanine, which are released under various pathological conditions and show neuroprotective properties, were then studied. In the presence of the glycine receptor blocker strychnine (1μM), both taurine (0.3-1mM) and β-alanine (0.3mM) activated sustained anionic currents, which were partly blocked by TPMPA (100μM). Thus, both β amino acids activated ρ-containing GABA receptors in hypoglossal motoneurons. Bicuculline (20μM) reduced responses to taurine and β-alanine, but small sustained responses persisted in the presence of both strychnine and bicuculline. Responses to β-alanine were slightly increased by allopregnanolone, indicating a contribution of the bicuculline- and neurosteroid-sensitive GABAA receptors underlying tonic inhibition in these motoneurons. Since sustained activation of anionic channels inhibits most mature principal neurons, the ρ-containing GABA receptors permanently activated by taurine and β-alanine might contribute to some of their neuroprotective properties under damaging overexcitatory situations. PMID:27246441

  9. Four Weeks of Balance Training does not Affect Ankle Joint Stiffness in Subjects with Unilateral Chronic Ankle Instability

    PubMed Central

    Jain, Tarang Kumar; Wauneka, Clayton N.; Liu, Wen

    2016-01-01

    Background Balance training has been shown to be effective in preventing ankle sprain recurrences in subjects with chronic ankle instability (CAI) but the biomechanical pathways underlying the clinical outcomes are still unknown. This study was conducted to determine if a 4-week balance training intervention can alter the mechanical characteristics in ankles with CAI. Methods Twenty-two recreationally active subjects with unilateral CAI were randomized to either a control (n = 11, 35.1 ± 9.3 years) or intervention (n = 11, 33.5 ± 6.6 years) group. Subjects in the intervention group were trained on the affected limb with static and dynamic components using a Biodex balance stability system for 4-weeks. The ankle joint stiffness and neutral zone in inversion and eversion directions on the involved and uninvolved limbs was measured at baseline and post-intervention using a dynamometer. Results At baseline, the mean values of the inversion stiffness (0.69 ± 0.37 Nm/degree) in the involved ankle was significantly lower (p < 0.011, 95% CI [0.563, 0.544]) than that of uninvolved contralateral ankle (0.99 ± 0.41 Nm/degree). With the available sample size, the eversion stiffness, inversion neutral zone, and eversion neutral zone were not found to be significantly different between the involved and uninvolved contralateral ankles. The 4-week balance training intervention failed to show any significant effect on the passive ankle stiffness and neutral zones in inversion and eversion. Conclusion Decreased inversion stiffness in the involved chronic unstable ankle was found that of uninvolved contralateral ankle. The 4-week balance training program intervention was ineffective in altering the mechanical characteristics of ankles with CAI. Level of evidence Randomized controlled clinical trial; Level of evidence, 1.

  10. Rehabilitation of the Ankle after Acute Sprain or Chronic Instability.

    ERIC Educational Resources Information Center

    Mattacola, Carl G.; Dwyer, Maureen K.

    2002-01-01

    Outlines rehabilitation concepts applicable to acute and chronic ankle injury, providing evidence for current techniques used in ankle rehabilitation and describing a functional rehabilitation program that progresses from basic to advanced, while taking into account empirical data from the literature and clinical practice. The article notes that…

  11. Review on design and control aspects of ankle rehabilitation robots.

    PubMed

    Jamwal, Prashant K; Hussain, Shahid; Xie, Sheng Q

    2015-03-01

    Ankle rehabilitation robots can play an important role in improving outcomes of the rehabilitation treatment by assisting therapists and patients in number of ways. Consequently, few robot designs have been proposed by researchers which fall under either of the two categories, namely, wearable robots or platform-based robots. This paper presents a review of both kinds of ankle robots along with a brief analysis of their design, actuation and control approaches. While reviewing these designs it was observed that most of them are undesirably inspired by industrial robot designs. Taking note of the design concerns of current ankle robots, few improvements in the ankle robot designs have also been suggested. Conventional position control or force control approaches, being used in the existing ankle robots, have been reviewed. Apparently, opportunities of improvement also exist in the actuation as well as control of ankle robots. Subsequently, a discussion on most recent research in the development of novel actuators and advanced controllers based on appropriate physical and cognitive human-robot interaction has also been included in this review. Implications for Rehabilitation Ankle joint functions are restricted/impaired as a consequence of stroke or injury during sports or otherwise. Robots can help in reinstating functions faster and can also work as tool for recording rehabilitation data useful for further analysis. Evolution of ankle robots with respect to their design and control aspects has been discussed in the present paper and a novel design with futuristic control approach has been proposed. PMID:24320195

  12. Simultaneous bilateral total ankle replacement using a 3-component prosthesis

    PubMed Central

    2011-01-01

    Background and purpose Total ankle replacement is an established surgical procedure in patients with end-stage ankle osteoarthritis. We analyzed complications and medium-term results in patients with simultaneous bilateral total ankle replacement. Patients and methods 10 women and 16 men, mean age 60 (SD 13) years, were followed for a median of 5 (2–10) years. Results There were no intraoperative or perioperative complications, with the exception of 1 patient with prolonged wound healing. Major revision surgery was necessary in 6 of the 52 ankles, including 4 revisions of prosthetic components. The average pain score decreased from 6.9 (4−10) to 1.8 (0−4) points. The American Orthopaedic Foot and Ankle Society hindfoot score increased from 32 (SD 14) points preoperatively to 74 (SD 12) points postoperatively. The average range of motion increased from 28° (SD 12) preoperatively to 38° (SD 9) postoperatively. All 8 categories of SF-36 score improved. Interpretation Simultaneous bilateral total ankle replacement is a suitable method for restoration of function and attainment of pain relief in patients with bilateral end-stage ankle osteoarthritis. The results of this procedure, including complication rates, revision rates, and functional outcome, are comparable to those reported in patients with unilateral total ankle replacement. PMID:21999622

  13. Direct measurement of the intrinsic ankle stiffness during standing.

    PubMed

    Vlutters, M; Boonstra, T A; Schouten, A C; van der Kooij, H

    2015-05-01

    Ankle stiffness contributes to standing balance, counteracting the destabilizing effect of gravity. The ankle stiffness together with the compliance between the foot and the support surface make up the ankle-foot stiffness, which is relevant to quiet standing. The contribution of the intrinsic ankle-foot stiffness to balance, and the ankle-foot stiffness amplitude dependency remain a topic of debate in the literature. We therefore developed an experimental protocol to directly measure the bilateral intrinsic ankle-foot stiffness during standing balance, and determine its amplitude dependency. By applying fast (40 ms) ramp-and-hold support surface rotations (0.005-0.08 rad) during standing, reflexive contributions could be excluded, and the amplitude dependency of the intrinsic ankle-foot stiffness was investigated. Results showed that reflexive activity could not have biased the torque used for estimating the intrinsic stiffness. Furthermore, subjects required less recovery action to restore balance after bilateral rotations in opposite directions compared to rotations in the same direction. The intrinsic ankle-foot stiffness appears insufficient to ensure balance, ranging from 0.93±0.09 to 0.44±0.06 (normalized to critical stiffness 'mgh'). This implies that changes in muscle activation are required to maintain balance. The non-linear stiffness decrease with increasing rotation amplitude supports the previous published research. With the proposed method reflexive effects can be ruled out from the measured torque without any model assumptions, allowing direct estimation of intrinsic stiffness during standing. PMID:25843262

  14. Ankle moment generation and maximum-effort curved sprinting performance.

    PubMed

    Luo, Geng; Stefanyshyn, Darren

    2012-11-15

    Turning at high speed along acute curves is crucial for athletic performance. One determinant of curved sprinting speed is the ground reaction force that can be created by the supporting limb; the moment generated at the ankle joint may influence such force generation. Body lean associated with curved sprints positions the ankle joints in extreme in-/eversion, and may hinder the ankle moment generation. To examine the influence of ankle moment generation on curved sprinting performance, 17 male subjects performed maximum-effort curved sprints in footwear with and without a wedge. The wedged footwear was constructed with the intention to align the ankle joints closer to their neutral frontal-plane configuration during counter-clockwise curved sprints so greater joint moments might be generated. We found, with the wedged footwear, the average eversion angle of the inside leg ankle was reduced, and the plantarflexion moment generation increased significantly. Meanwhile, the knee extension moment remained unchanged. With the wedged footwear, stance-average centripetal ground reaction force increased significantly while no difference in the vertical ground reaction force was detected. The subjects created a greater centripetal ground reaction impulse in the wedged footwear despite a shortened stance phase when compared to the control. Stance-average curved sprinting speed improved by 4.3% with the wedged footwear. The changes in ankle moment and curved sprinting speed observed in the current study supports the notion that the moment generation at the ankle joint may be a performance constraint for curved sprinting. PMID:23022207

  15. Systematic review of chronic ankle instability in children

    PubMed Central

    2014-01-01

    Background Chronic ankle instability (CAI) is a disabling condition often encountered after ankle injury. Three main components of CAI exist; perceived instability; mechanical instability (increased ankle ligament laxity); and recurrent sprain. Literature evaluating CAI has been heavily focused on adults, with little attention to CAI in children. Hence, the objective of this study was to systematically review the prevalence of CAI in children. Methods Studies were retrieved from major databases from earliest records to March 2013. References from identified articles were also examined. Studies involving participants with CAI, classified by authors as children, were considered for inclusion. Papers investigating traumatic instability or instability arising from fractures were excluded. Two independent examiners undertook all stages of screening, data extraction and methodological quality assessments. Screening discrepancies were resolved by reaching consensus. Results Following the removal of duplicates, 14,263 papers were screened for eligibility against inclusion and exclusion criteria. Nine full papers were included in the review. Symptoms of CAI evaluated included perceived and mechanical ankle instability along with recurrent ankle sprain. In children with a history of ankle sprain, perceived instability was reported in 23-71% whilst mechanical instability was found in 18-47% of children. A history of recurrent ankle sprain was found in 22% of children. Conclusion Due to the long-lasting impacts of CAI, future research into the measurement and incidence of ankle instability in children is recommended. PMID:24641786

  16. Kinematics of ankle taping after a training session.

    PubMed

    Meana, M; Alegre, L M; Elvira, J L L; Aguado, X

    2008-01-01

    This study aimed to test the effectiveness of ankle taping on the limitation of forced supination during a change of direction, as well as the losses of effectiveness after a 30-minute training session. Fifteen young men with no ankle injury volunteered for the study. The static and dynamic ranges of movement (ROM) were measured before and after a training session. The dynamic measurements were recorded using high-speed 3D photogrammetry. The differences between static and dynamic measures of ankle supination and plantar flexion were significant. The losses of effectiveness during supination and ankle plantar flexion restriction were 42.3 % and 47.6 %, respectively. Ankle taping was effective in restricting the maximal static ROMs before a training session, but the effectiveness decreased after 30 min of training. The present study shows the necessity of performing dynamic ROM analysis of sports techniques involved in the ankle sprain mechanism in order to determine the degree of tape restriction after a training session, because there were differences between static and dynamic ankle ROMs. The lack of effects on the restriction of the dynamic plantar flexion would bring into question the necessity of ankle taping in subjects without previous injuries. PMID:17614032

  17. Recycling Energy to Restore Impaired Ankle Function during Human Walking

    PubMed Central

    Collins, Steven H.; Kuo, Arthur D.

    2010-01-01

    Background Humans normally dissipate significant energy during walking, largely at the transitions between steps. The ankle then acts to restore energy during push-off, which may be the reason that ankle impairment nearly always leads to poorer walking economy. The replacement of lost energy is necessary for steady gait, in which mechanical energy is constant on average, external dissipation is negligible, and no net work is performed over a stride. However, dissipation and replacement by muscles might not be necessary if energy were instead captured and reused by an assistive device. Methodology/Principal Findings We developed a microprocessor-controlled artificial foot that captures some of the energy that is normally dissipated by the leg and “recycles” it as positive ankle work. In tests on subjects walking with an artificially-impaired ankle, a conventional prosthesis reduced ankle push-off work and increased net metabolic energy expenditure by 23% compared to normal walking. Energy recycling restored ankle push-off to normal and reduced the net metabolic energy penalty to 14%. Conclusions/Significance These results suggest that reduced ankle push-off contributes to the increased metabolic energy expenditure accompanying ankle impairments, and demonstrate that energy recycling can be used to reduce such cost. PMID:20174659

  18. Force-controlled dynamic wear testing of total ankle replacements.

    PubMed

    Reinders, Jörn; von Stillfried, Falko; Altan, Emel; Sonntag, Robert; Heitzmann, Daniel W W; Kretzer, Jan Philippe

    2015-01-01

    Currently, our knowledge of wear performance in total ankle replacements is limited. The aim of this study is to develop a scenario for force-controlled testing and wear testing of total ankle replacements. A force-controlled wear test was developed: based on cadaver measurements, the passive stabilization (ligaments and soft tissue) of the ankle joint was characterized and a restraint model for ankle stabilization was developed. Kinematics and kinetics acting at the replaced ankle joint were defined based on literature data and gait analysis. Afterwards, force-controlled wear testing was carried out on a mobile, three-component, total ankle replacement design. Wear was assessed gravimetrically and wear particles were analyzed. Wear testing resulted in a mean wear rate of 18.2±1.4mm(3)/10(6) cycles. Wear particles showed a mean size of 0.23μm with an aspect ratio of 1.61±0.96 and a roundness of 0.62±0.14. Wear testing of total ankle replacement shows that a relevant wear mass is generated with wear particles in a biologically relevant size range. The developed wear test provides a basis for future wear testing of total ankle replacements. PMID:25448342

  19. Pharmacologically induced enhancement of recurrent inhibition in humans: effects on motoneurone discharge patterns.

    PubMed

    Mattei, Benjamin; Schmied, Annie; Mazzocchio, Riccardo; Decchi, Barbara; Rossi, Alessandro; Vedel, Jean-Pierre

    2003-04-15

    The aim of the present study was to investigate the effects of spinal recurrent inhibition on human motoneurone discharge patterns. The tonic discharge activity of motor unit pairs was recorded in the extensor carpi radialis (ECR) and abductor digiti minimi (ADM) muscles during voluntary isometric contraction. While undergoing continuous intravenous saline (NaCl 0.9 %) perfusion, the subjects were given a short lasting injection of L-acetylcarnitine (L-Ac), which has been found to potentiate recurrent inhibition in humans. The variability, synchronization and coherence of the motor unit discharges were analysed during four successive test periods (lasting 2-3 min each). A significant decrease in the inter-spike interval (ISI) coefficient of variation was observed in the discharge patterns of the motor units tested in the ECR and not in the ADM, which were not accompanied by any consistent changes in the mean ISIs of the motor unit activity in either muscle. The L-Ac injection also led to a significant increase in the synchronization in half of the motor unit pairs tested in the ECR muscle (n = 29), whereas no consistent changes were observed with the ADM motor units (n = 25). However, coherence analysis failed to reveal any consistent differences in the incidence of significant values of coherence spectrum between the pre-injection and injection periods among the motor unit pairs tested with either saline or L-Ac injections, in either the ECR or ADM muscles. The contrasting effects on the variability and the synchronization of the motor unit discharges observed with ECR motoneurones known to undergo recurrent inhibition and with ADM motoneurones known to lack recurrent inhibition suggest that the drug may have specific effects which are mediated by an enhancement of the Renshaw cell activity. The decrease in the ISI variability is in line with the hypothesis that recurrent inhibition may contribute along with the post-spike after-hyperpolarization to limiting the

  20. Spinal inhibition of descending command to soleus motoneurons is removed prior to dorsiflexion

    PubMed Central

    Geertsen, Svend S; van de Ruit, Mark; Grey, Michael J; Nielsen, Jens B

    2011-01-01

    Abstract It has recently been demonstrated that soleus motor-evoked potentials (MEPs) are facilitated prior to the onset of dorsiflexion. The purpose of this study was to examine if this could be explained by removal of spinal inhibition of the descending command to soleus motoneurons. To test this, we investigated how afferent inputs from the tibialis anterior muscle modulate the corticospinal activation of soleus spinal motoneurons at rest, during static contraction and prior to movement. MEPs activated by transcranial magnetic stimulation (TMS) and Hoffmann reflexes (H-reflexes), activated by electrical stimulation of the posterior tibial nerve (PTN), were conditioned by prior stimulation of the common peroneal nerve (CPN) at a variety of conditioning–test (CT) intervals. MEPs in the precontracted soleus muscle were inhibited when the TMS pulse was preceded by CPN stimulation with a CT interval of 35 ms, and they were facilitated for CT intervals of 50–55 ms. A similar inhibition of the soleus H-reflex was not observed. To investigate which descending pathways might be responsible for the afferent-evoked inhibition and facilitation, we examined the effect of CPN stimulation on short-latency facilitation (SLF) and long-latency facilitation (LLF) of the soleus H-reflex induced by a subthreshold TMS pulse at different CT intervals. SLF is known to reflect the excitability of the fastest conducting, corticomotoneuronal cells whereas LLF is believed to be caused by more indirect descending pathways. At CT intervals of 40–45 ms, the LLF was significantly more inhibited compared to the SLF when taking the effect on the H-reflex into account. Finally, we investigated how the CPN-induced inhibition and facilitation of the soleus MEP were modulated prior to dorsiflexion. Whereas the late facilitation (CT interval: 55 ms) was similar prior to dorsiflexion and at rest, no inhibition could be evoked at the earlier latency (CT interval: 35 ms) prior to onset of

  1. Clinical experiences with three different designs of ankle prostheses.

    PubMed

    Rippstein, Pascal F

    2002-12-01

    Until 1995, fusion was in our institution the only rational surgical option for a severe ankle arthrosis. Consistent reports about good mid- and long-term results with ankle replacement allowed us to change our minds. Ankle replacement became the gold standard and fusion was then almost totally banished. Because ankle arthrosis can be morphologically different from one patient to another, we soon believed that one single type of ankle prosthesis would not be the universal optimal solution for all patients. We therefore divided the ankle arthrosis into three groups. Each group shows the best solution from each of the ankle prostheses with which we had gained experience (Agility, STAR, and BP). The Agility prosthesis, which was indicated for ankles with extremely damaged geometry, did not restore sufficiently the ankle motion. Preoperatively stiff ankles remained stiff postoperatively. Additionally, significant residual pain was more likely to occur in those patients. These cases did not show significant advantages compared with ankle fusion, especially from a functional point of view. Fusion for these stiff ankles is therefore today our first treatment of choice. In our experience, the malleolar joints do not have to be replaced. Even a severe arthrosis at this level does not produce significant pain, provided that osteophytes have been removed and joint height has been restored by the implanted prosthesis. It is our strong belief that these malleolar joints are also less sensitive to pain, similar to the femoropatellar joint. For these reasons, a replacement of the malleolar joints and the resurfacing of the talar sides is not necessary. Leaving the talar sides untouched requires less bone resection and makes the implantation of the talar component easier. Although we obtained good results with the STAR prosthesis, we progressively abandoned it because of these reasons, and we preferred the BP prosthesis. The BP prosthesis works on the same biomechanic principle as

  2. Understanding acute ankle ligamentous sprain injury in sports

    PubMed Central

    Fong, Daniel TP; Chan, Yue-Yan; Mok, Kam-Ming; Yung, Patrick SH; Chan, Kai-Ming

    2009-01-01

    This paper summarizes the current understanding on acute ankle sprain injury, which is the most common acute sport trauma, accounting for about 14% of all sport-related injuries. Among, 80% are ligamentous sprains caused by explosive inversion or supination. The injury motion often happens at the subtalar joint and tears the anterior talofibular ligament (ATFL) which possesses the lowest ultimate load among the lateral ligaments at the ankle. For extrinsic risk factors to ankle sprain injury, prescribing orthosis decreases the risk while increased exercise intensity in soccer raises the risk. For intrinsic factors, a foot size with increased width, an increased ankle eversion to inversion strength, plantarflexion strength and ratio between dorsiflexion and plantarflexion strength, and limb dominance could increase the ankle sprain injury risk. Players with a previous sprain history, players wearing shoes with air cells, players who do not stretch before exercising, players with inferior single leg balance, and overweight players are 4.9, 4.3, 2.6, 2.4 and 3.9 times more likely to sustain an ankle sprain injury. The aetiology of most ankle sprain injuries is incorrect foot positioning at landing – a medially-deviated vertical ground reaction force causes an explosive supination or inversion moment at the subtalar joint in a short time (about 50 ms). Another aetiology is the delayed reaction time of the peroneal muscles at the lateral aspect of the ankle (60–90 ms). The failure supination or inversion torque is about 41–45 Nm to cause ligamentous rupture in simulated spraining tests on cadaver. A previous case report revealed that the ankle joint reached 48 degrees inversion and 10 degrees internal rotation during an accidental grade I ankle ligamentous sprain injury during a dynamic cutting trial in laboratory. Diagnosis techniques and grading systems vary, but the management of ankle ligamentous sprain injury is mainly conservative. Immobilization should not

  3. Orthobiologics in Foot and Ankle Surgery.

    PubMed

    Lin, Sheldon S; Montemurro, Nicholas J; Krell, Ethan S

    2016-02-01

    Exploration into the molecular aspects of the healing process has led to the development of autologous and recombinant biologic agents. These products, collectively known as orthobiologics, have the potential to optimize favorable outcomes with respect to bone and soft-tissue restoration and to maximize the natural healing response. These orthobiologics include platelet-derived growth factor, bone morphogenetic proteins, and platelet-rich plasma. Although the usefulness of these growth factors is well described in various fields of surgery, few data exist to support or oppose the specific application of growth factors in foot and ankle surgery. PMID:26803546

  4. Arthroscopic Approach to Posterior Ankle Impingement.

    PubMed

    Theodoulou, Michael H; Bohman, Laura

    2016-10-01

    Posterior ankle pain can occur for many reasons. If it is produced by forced plantarflexion of the foot, it is often a result of impingement from an enlarged posterior talar process or an os trigonum. This condition may present in an acute or chronic state. Management is initially nonoperative, but surgical treatments are available. This condition is often seen in athletes, so procedures that limit surgical trauma and allow early return to activity are ideal. An arthroscopic approach for this disorder produces good outcomes with limited complications. Understanding the indications, local anatomy, and surgical technique, allows good, reproducible outcomes. PMID:27599438

  5. Clinical assessment and management of ankle sprains.

    PubMed

    Myrick, Karen M

    2014-01-01

    Ankle sprains are a common occurrence and are frequently either undertreated or overtreated. With the incidence estimated at more than 3 million a year and at a rate of 2.15/1,000 in the United States alone, this is an orthopaedic injury that providers should be acutely aware of and successfully able to evaluate and treat. This clinical feature will provide a thorough review of the mechanism of injury, the history and physical examination, and the classification and management of these injuries. Clinical red flags are discussed. PMID:25233201

  6. Robotic Ankle for Omnidirectional Rock Anchors

    NASA Technical Reports Server (NTRS)

    Parness, Aaron; Frost, Matthew; Thatte, Nitish

    2013-01-01

    Future robotic exploration of near-Earth asteroids and the vertical and inverted rock walls of lava caves and cliff faces on Mars and other planetary bodies would require a method of gripping their rocky surfaces to allow mobility without gravitational assistance. In order to successfully navigate this terrain and drill for samples, the grippers must be able to produce anchoring forces in excess of 100 N. Additionally, the grippers must be able to support the inertial forces of a moving robot, as well gravitational forces for demonstrations on Earth. One possible solution would be to use microspine arrays to anchor to rock surfaces and provide the necessary load-bearing abilities for robotic exploration of asteroids. Microspine arrays comprise dozens of small steel hooks supported on individual suspensions. When these arrays are dragged along a rock surface, the steel hooks engage with asperities and holes on the surface. The suspensions allow for individual hooks to engage with asperities while the remaining hooks continue to drag along the surface. This ensures that the maximum possible number of hooks engage with the surface, thereby increasing the load-bearing abilities of the gripper. Using the microspine array grippers described above as the end-effectors of a robot would allow it to traverse terrain previously unreachable by traditional wheeled robots. Furthermore, microspine-gripping robots that can perch on cliffs or rocky walls could enable a new class of persistent surveillance devices for military applications. In order to interface these microspine grippers with a legged robot, an ankle is needed that can robotically actuate the gripper, as well as allow it to conform to the large-scale irregularities in the rock. The anchor serves three main purposes: deploy and release the anchor, conform to roughness or misalignment with the surface, and cancel out any moments about the anchor that could cause unintentional detachment. The ankle design contains a

  7. Finite element analysis of a composite artificial ankle

    NASA Technical Reports Server (NTRS)

    Perkins, Leigh Ann; Johnston, Lawrence; Denniston, Charles; Czekalski, Blaise E.

    1993-01-01

    Ultra-light carbon fiber composite materials are being utilized in artificial limbs with increasing frequency in recent years. Dr. Arthur Copes, an orthotist from Baton Rouge, Louisiana, has developed a graphite expoxy composite material artificial ankle (Copes/Bionic Ankle) that is intended to be used by amputees who require the most advanced above-and-below-the-knee prosthetic devices. The Copes/Bionic Ankle is designed to reproduce the function of the natural ankle joint by allowing the composite material to act as a spring mechanism without the use of metal mechanical parts. NASA Marshall Space Flight Center has agreed to participate in the design effort by providing the structural analysis of the artificial ankle design.

  8. Technique of Arthroscopic Treatment of Impingement After Total Ankle Arthroplasty.

    PubMed

    Gross, Christopher E; Neumann, Julie A; Godin, Jonathan A; DeOrio, James K

    2016-04-01

    Rates of medial and/or lateral gutter impingement after total ankle replacement are not insignificant. If impingement should occur, it typically arises an average of 17 months after total ankle replacement. Our patient underwent treatment for right ankle medial gutter bony impingement with arthroscopic debridement 5 years after her initial total ankle replacement. Standard anteromedial and anterolateral portals and a 30° 2.7-mm-diameter arthroscope were used. An aggressive soft-tissue and bony resection was performed using a combination of curettes, a 3.5-mm shaver, a 5.5-mm unsheathed burr, a drill, and a radiofrequency ablator. This case shows that arthroscopic treatment is an effective and potentially advantageous alternative to open treatment of impingement after total ankle replacement. In addition, symptoms of impingement often improve in a short amount of time after arthroscopic debridement of the medial and/or lateral gutter. PMID:27354942

  9. Functional Design in Rehabilitation: Modular Mechanisms for Ankle Complex

    PubMed Central

    2016-01-01

    This paper is aimed at presenting an innovative ankle rehabilitation device based on a parallel mechanism. A functional analysis and design are described to obtain a device able to guarantee ankle movement while patient's body remains stationary. Human ankle is a challenging context where a series of joints are highly integrated. The proposed rehabilitation device permits a patient with walking defects to improve his or her gait. The research focuses on plantar-flexion-dorsiflexion movement. The robust design starts from an accurate modelling of ankle movements during walking, assessing motion data from healthy individuals and patients. The kinematics analysis and functional evaluations lead the study and development of the articulated system. In particular, results of simulations support the effectiveness of the current design. A 3D prototype is presented highlighting that the ankle motion is successfully demonstrated. PMID:27524881

  10. Total ankle replacement – surgical treatment and rehabilitation

    PubMed Central

    Krogulec, Zbigniew; Turski, Piotr; Przepiórski, Emil; Małdyk, Paweł; Księżopolska-Orłowska, Krystyna

    2015-01-01

    Functions of the ankle joint are closely connected with the gait and ability to maintain an upright position. Degenerative lesions of the joint directly contribute to postural disorders and greatly restrict propulsion of the foot, thus leading to abnormal gait. Development of total ankle replacement is connected with the use of the method as an efficient treatment of joint injuries and continuation of achievements in hip and knee surgery. The total ankle replacement technique was introduced as an alternative to arthrodesis, i.e. surgical fixation, which made it possible to preserve joint mobility and to improve gait. Total ankle replacement is indicated in post-traumatic degenerative joint disease and joint destruction secondary to rheumatoid arthritis. In this paper, total ankle replacement and various types of currently used endoprostheses are discussed. The authors also describe principles of early postoperative rehabilitation as well as rehabilitation in the outpatient setting. PMID:27407223

  11. Foot and ankle injuries in the barefoot sports.

    PubMed

    Vormittag, Kara; Calonje, Ronald; Briner, William W

    2009-01-01

    Playing sports barefoot has been contested since the very beginnings of athletic competition. Even today, some data suggest that shoes may limit the adaptive pronation that occurs after footstrike during running gait. This pronation likely protects runners from injury. Boardsport participants who perform their sports barefoot on the water seem to be at risk for foot and ankle injuries. The high-impact forces in gymnastics place participants at risk for foot and ankle injuries, as well. Swimming and diving have a low rate of foot and ankle injuries. The risk of ankle sprain in beach volleyball, which is played barefoot, seems to be lower than that for indoor volleyball, played wearing shoes. Martial arts place competitors at risk for injuries to the foot and ankle from torsional and impact mechanisms. Athletes who hope to return to barefoot competition after injury should perform their rehabilitation in their bare feet. PMID:19741354

  12. The effects of tetrodotoxin-induced muscle paralysis on the physiological properties of muscle units and their innervating motoneurons in rat.

    PubMed Central

    Gardiner, P F; Seburn, K L

    1997-01-01

    1. Although the inactivity of a slow muscle (cat soleus) induced via nerve impulse blockade has been demonstrated to have some axotomy-like effects (decreased after-hyperpolarization (AHP) duration) on its innervating motoneurons, the reported effects of inactivity on motoneurons which innervate fast muscles containing mixtures of motor unit types are equivocal. This study was designed to determine the effect of a period (2 weeks) of complete hindlimb muscle paralysis, via tetrodotoxin (TTX) blockade of sciatic nerve impulses, on the contractile (muscle units) and electrophysiological (motoneurons) properties of motor units in the rat gastrocnemius. Motoneuron properties were also compared with those of rats subjected to sciatic nerve axotomy 2 weeks earlier. 2. At the time of the terminal experiment (24 h after the removal of the TTX delivery system) in anaesthetized animals, properties of tibial motoneurons (i.e. rheobase current, input resistance, time course of after-potentials) were determined using conventional microelectrode techniques. For those tibial motoneurons innervating the gastrocnemius, muscle unit responses (i.e. twitch force and time course, maximum tetanic tension, fatigability) were also recorded in response to current injection. 3. Consistent with previously reported whole-muscle responses to TTX-induced disuse, the TTX-treated gastrocnemius muscle units showed weaker tetanic forces, prolonged twitches and elevated twitch/tetanic ratios. These effects were similar for motor units classified as small, medium and large according to their tetanic tension-generating capacities. Muscle unit fatigue resistances appeared to be unchanged. 4. The mean values, distributions and ranges of tibial motoneuron properties were similar between control and TTX-treated groups for rheobase, input resistance and AHP half-decay time. In the case of the latter, the proportion of motoneurons possessing "slow' AHP half-decay times (> 20 ms) was not significantly

  13. Lateral and syndesmotic ankle sprain injuries: a narrative literature review

    PubMed Central

    Dubin, Joshua C.; Comeau, Doug; McClelland, Rebecca I.; Dubin, Rachel A.; Ferrel, Ernest

    2011-01-01

    Objective The purpose of this article is to review the literature that discusses normal anatomy and biomechanics of the foot and ankle, mechanisms that may result in a lateral ankle sprain or syndesmotic sprain, and assessment and diagnostic procedures, and to present a treatment algorithm based on normal ligament healing principles. Methods Literature was searched for years 2000 to 2010 in PubMed and CINAHL. Key search terms were ankle sprain$, ankle injury and ankle injuries, inversion injury, proprioception, rehabilitation, physical therapy, anterior talofibular ligament, syndesmosis, syndesmotic injury, and ligament healing. Discussion Most ankle sprains respond favorably to nonsurgical treatment, such as those offered by physical therapists, doctors of chiropractic, and rehabilitation specialists. A comprehensive history and examination aid in diagnosing the severity and type of ankle sprain. Based on the diagnosis and an understanding of ligament healing properties, a progressive treatment regimen can be developed. During the acute inflammatory phase, the goal of care is to reduce inflammation and pain and to protect the ligament from further injury. During the reparative and remodeling phase, the goal is to progress the rehabilitation appropriately to facilitate healing and restore the mechanical strength and proprioception. Radiographic imaging techniques may need to be used to rule out fractures, complete ligament tears, or instability of the ankle mortise. A period of immobilization and ambulating with crutches in a nonweightbearing gait may be necessary to allow for proper ligament healing before commencing a more active treatment approach. Surgery should be considered in the case of grade 3 syndesmotic sprain injuries or those ankle sprains that are recalcitrant to conservative care. Conclusion An accurate diagnosis and prompt treatment can minimize an athlete's time lost from sport and prevent future reinjury. Most ankle sprains can be successfully

  14. The role of series ankle elasticity in bipedal walking.

    PubMed

    Zelik, Karl E; Huang, Tzu-Wei P; Adamczyk, Peter G; Kuo, Arthur D

    2014-04-01

    The elastic stretch-shortening cycle of the Achilles tendon during walking can reduce the active work demands on the plantarflexor muscles in series. However, this does not explain why or when this ankle work, whether by muscle or tendon, needs to be performed during gait. We therefore employ a simple bipedal walking model to investigate how ankle work and series elasticity impact economical locomotion. Our model shows that ankle elasticity can use passive dynamics to aid push-off late in single support, redirecting the body's center-of-mass (COM) motion upward. An appropriately timed, elastic push-off helps to reduce dissipative collision losses at contralateral heelstrike, and therefore the positive work needed to offset those losses and power steady walking. Thus, the model demonstrates how elastic ankle work can reduce the total energetic demands of walking, including work required from more proximal knee and hip muscles. We found that the key requirement for using ankle elasticity to achieve economical gait is the proper ratio of ankle stiffness to foot length. Optimal combination of these parameters ensures proper timing of elastic energy release prior to contralateral heelstrike, and sufficient energy storage to redirect the COM velocity. In fact, there exist parameter combinations that theoretically yield collision-free walking, thus requiring zero active work, albeit with relatively high ankle torques. Ankle elasticity also allows the hip to power economical walking by contributing indirectly to push-off. Whether walking is powered by the ankle or hip, ankle elasticity may aid walking economy by reducing collision losses. PMID:24365635

  15. The role of series ankle elasticity in bipedal walking

    PubMed Central

    Zelik, Karl E.; Huang, Tzu-Wei P.; Adamczyk, Peter G.; Kuo, Arthur D.

    2014-01-01

    The elastic stretch-shortening cycle of the Achilles tendon during walking can reduce the active work demands on the plantarflexor muscles in series. However, this does not explain why or when this ankle work, whether by muscle or tendon, needs to be performed during gait. We therefore employ a simple bipedal walking model to investigate how ankle work and series elasticity impact economical locomotion. Our model shows that ankle elasticity can use passive dynamics to aid push-off late in single support, redirecting the body's center-of-mass (COM) motion upward. An appropriately timed, elastic push-off helps to reduce dissipative collision losses at contralateral heelstrike, and therefore the positive work needed to offset those losses and power steady walking. Thus, the model demonstrates how elastic ankle work can reduce the total energetic demands of walking, including work required from more proximal knee and hip muscles. We found that the key requirement for using ankle elasticity to achieve economical gait is the proper ratio of ankle stiffness to foot length. Optimal combination of these parameters ensures proper timing of elastic energy release prior to contralateral heelstrike, and sufficient energy storage to redirect the COM velocity. In fact, there exist parameter combinations that theoretically yield collision-free walking, thus requiring zero active work, albeit with relatively high ankle torques. Ankle elasticity also allows the hip to power economical walking by contributing indirectly to push-off. Whether walking is powered by the ankle or hip, ankle elasticity may aid walking economy by reducing collision losses. PMID:24365635

  16. Syndesmosis and lateral ankle sprains in the National Football League.

    PubMed

    Osbahr, Daryl C; Drakos, Mark C; O'Loughlin, Padhraig F; Lyman, Stephen; Barnes, Ronnie P; Kennedy, John G; Warren, Russell F

    2013-11-01

    Syndesmosis sprains in the National Football League (NFL) can be a persistent source of disability, especially compared with lateral ankle injuries. This study evaluated syndesmosis and lateral ankle sprains in NFL players to allow for better identification and management of these injuries. Syndesmosis and lateral ankle sprains from a single NFL team database were reviewed over a 15-year period, and 32 NFL team physicians completed a questionnaire detailing their management approach. A comparative analysis was performed analyzing several variables, including diagnosis, treatment methods, and time lost from sports participation. Thirty-six syndesmosis and 53 lateral ankle sprains occurred in the cohort of NFL players. The injury mechanism typically resulted from direct impact in the syndesmosis and torsion in the lateral ankle sprain group (P=.034). All players were managed nonoperatively. The mean time lost from participation was 15.4 days in the syndesmosis and 6.5 days in the lateral ankle sprain groups (P⩽.001). National Football League team physicians varied treatment for syndesmosis sprains depending on the category of diastasis but recommended nonoperative management for lateral ankle sprains. Syndesmosis sprains in the NFL can be a source of significant disability compared with lateral ankle sprains. Successful return to play with nonoperative management is frequently achieved for syndesmosis and lateral ankle sprains depending on injury severity. With modern treatment algorithms for syndesmosis sprains, more aggressive nonoperative treatment is advocated. Although the current study shows that syndesmosis injuries require longer rehabilitation periods when compared with lateral ankle sprains, the time lost from participation may not be as prolonged as previously reported. PMID:24200441

  17. [Unexpected revision procedures treating ankle fractures].

    PubMed

    Richter, J; Pommer, A; Breuer, R; Hullmann, S; Heyde, D V; Dávid, A

    2012-06-01

    The purpose of the present study was to analyze the risk factors associated with unexpected second procedures and strategies of revision surgery. Within a 5 year period 647 patients with closed ankle fractures AO type 44 were identified of which 77 (11.9%) needed revision surgery. Complications were addressed to 4 main groups: deep infections (IG) were seen in 29 patients (4.5%), problems with primary wound closure (WG) in 22 patients (3.4%), insufficient reduction (KG) in 22 patients (3.4%) and other causes (RG) included 4 patients (0.6%). Significant predictive factors for soft tissue complications were higher age, comorbidities with peripheral arteriosclerosis, high American Society of Anesthesiologists (ASA) score and diabetes mellitus. AO 44 type B2 and B3 fractures were often associated with soft tissue problems. The more complex fracture types AO 44 C1-C3 and A2-A3 were significantly associated with problems of insufficient congruency post-surgery. The distribution of the mean revision rate was significantly different (p<0.01) for all groups: IG 4.59, WG 3.5, KG 1.55, RG 1.25. In summary, we strongly recommend immediate reduction of displaced fractures and to consider a more detailed fracture classification. To reduce the amount of unexpected ankle procedures individual risk factors should be weighed against the advantages of optimal open reduction and internal fixation. PMID:21165587

  18. Lyme arthritis of the pediatric ankle.

    PubMed

    Aiyer, Amiethab; Walrath, Jessica; Hennrikus, William

    2014-10-01

    Lyme arthritis results from acute inflammation caused by the spirochete Borrelia burgdorferi. The number of cases per year has been rising since 2006, with a majority of patients being affected in the northeastern United States. Development of Lyme arthritis is of particular importance to the orthopedic surgeon because Lyme arthritis often presents as an acute episode of joint swelling and tenderness and may be confused with bacterial septic arthritis. Considering the vast difference in treatment management between these 2 pathologies, differentiating between them is of critical importance. Septic arthritis often needs to be addressed surgically, whereas Lyme arthritis can be treated with oral antibiotics alone. Laboratory testing for Lyme disease often results in a delay in diagnosis because many laboratories batch-test Lyme specimens only a few times per week because of increased expense. The authors present a case of Lyme arthritis in the pediatric ankle in an endemic region. No clear algorithm exists to delineate between septic arthritis and Lyme arthritis of the joint. Improved clinical guidelines for the identification and diagnosis of Lyme arthritis of the ankle are important so that appropriate antibiotics can be used and surgery can be avoided. PMID:25275987

  19. Arthroscopic Anatomy of the Ankle Joint.

    PubMed

    Ray, Ronald G

    2016-10-01

    There are a number of variations in the intra-articular anatomy of the ankle which should not be considered pathological under all circumstances. The anteromedial corner of the tibial plafond (between the anterior edge of the tibial plafond and the medial malleolus) can have a notch, void of cartilage and bone. This area can appear degenerative arthroscopically; it is actually a normal variant of the articular surface. The anterior inferior tibiofibular ligament (AITF) can possess a lower, accessory band which can impinge on the anterolateral edge of the talar dome. In some cases it can cause irritation along this area of the talus laterally. If it is creating local irritation it can be removed since it does not provide any additional stabilization to the syndesmosis. There is a beveled region at the anterior leading edge of the lateral and dorsal surfaces of the talus laterally. This triangular region is void of cartilage and subchondral bone. The lack of talar structure in this region allows the lower portion of the AITF ligament to move over the talus during end range dorsiflexion of the ankle, preventing impingement. The variation in talar anatomy for this area should not be considered pathological. PMID:27599433

  20. The foot and ankle of Australopithecus sediba.

    PubMed

    Zipfel, Bernhard; DeSilva, Jeremy M; Kidd, Robert S; Carlson, Kristian J; Churchill, Steven E; Berger, Lee R

    2011-09-01

    A well-preserved and articulated partial foot and ankle of Australopithecus sediba, including an associated complete adult distal tibia, talus, and calcaneus, have been discovered at the Malapa site, South Africa, and reported in direct association with the female paratype Malapa Hominin 2. These fossils reveal a mosaic of primitive and derived features that are distinct from those seen in other hominins. The ankle (talocrural) joint is mostly humanlike in form and inferred function, and there is some evidence for a humanlike arch and Achilles tendon. However, Au. sediba is apelike in possessing a more gracile calcaneal body and a more robust medial malleolus than expected. These observations suggest, if present models of foot function are correct, that Au. sediba may have practiced a unique form of bipedalism and some degree of arboreality. Given the combination of features in the Au. sediba foot, as well as comparisons between Au. sediba and older hominins, homoplasy is implied in the acquisition of bipedal adaptations in the hominin foot. PMID:21903807

  1. Ankle Bracing and the Neuromuscular Factors Influencing Joint Stiffness

    PubMed Central

    Zinder, Steven M; Granata, Kevin P; Shultz, Sandra J; Gansneder, Bruce M

    2009-01-01

    Context: Health care professionals commonly prescribe external stabilization to decrease the incidence and severity of ankle sprains. The mechanism for this decrease is not clearly understood. Examining the effects of ankle bracing on biomechanical stability and influencing factors may provide important information regarding the neuromuscular effects of bracing. Objective: To study the effects of 2 different ankle braces on the neuromuscular factors influencing ankle stiffness. Design: Mixed-model repeated-measures design. Setting: Research laboratory. Patients or Other Participants: Twenty-eight physically active participants composing 2 groups: 14 with unilateral functional ankle instability (age  =  26.19 ± 6.46 years, height  =  166.07 ± 12.90 cm, mass  =  69.90 ± 13.46 kg) and 14 with bilaterally stable ankles (age  =  23.76 ± 5.82 years, height  =  174.00 ± 11.67 cm, mass  =  68.60 ± 13.12 kg). Intervention(s): Participants were fitted with surface electromyography electrodes over the peroneus longus, peroneus brevis, tibialis anterior, and soleus muscles. Each participant received transient motion oscillations to his or her ankle on a custom-built medial-lateral swaying cradle in each of 3 conditions: no ankle brace (NB), lace-up brace (LU), and semirigid brace (SR). Main Outcome Measure(s): Ankle stiffness as measured by the cradle and preactivation levels (percentage of maximal voluntary isometric contraction) of the 4 test muscles. Results: Stiffness levels increased across brace conditions (NB  =  24.79 ± 6.59 Nm/rad, LU  =  28.29 ± 7.05 Nm/rad, SR  =  33.22 ± 8.78 Nm/rad; F2,52  =  66.185, P < .001). No differences were found between groups for rotational stiffness (stable  =  27.36 ± 6.17 Nm/rad, unstable  =  30.18 ± 8.21 Nm/rad; F1,26  =  1.084, P  =  .307). Preactivation levels did not change for any of the tested muscles with the application of an ankle brace (F2,52  =  1.326, P

  2. Epsin 1 Promotes Synaptic Growth by Enhancing BMP Signal Levels in Motoneuron Nuclei

    PubMed Central

    Chastain, Lerin R.; Royer, Suzanne M.; Bao, Hong; Reist, Noreen E.; Zhang, Bing

    2013-01-01

    Bone morphogenetic protein (BMP) retrograde signaling is crucial for neuronal development and synaptic plasticity. However, how the BMP effector phospho-Mother against decapentaplegic (pMad) is processed following receptor activation remains poorly understood. Here we show that Drosophila Epsin1/Liquid facets (Lqf) positively regulates synaptic growth through post-endocytotic processing of pMad signaling complex. Lqf and the BMP receptor Wishful thinking (Wit) interact genetically and biochemically. lqf loss of function (LOF) reduces bouton number whereas overexpression of lqf stimulates bouton growth. Lqf-stimulated synaptic overgrowth is suppressed by genetic reduction of wit. Further, synaptic pMad fails to accumulate inside the motoneuron nuclei in lqf mutants and lqf suppresses synaptic overgrowth in spinster (spin) mutants with enhanced BMP signaling by reducing accumulation of nuclear pMad. Interestingly, lqf mutations reduce nuclear pMad levels without causing an apparent blockage of axonal transport itself. Finally, overexpression of Lqf significantly increases the number of multivesicular bodies (MVBs) in the synapse whereas lqf LOF reduces MVB formation, indicating that Lqf may function in signaling endosome recycling or maturation. Based on these observations, we propose that Lqf plays a novel endosomal role to ensure efficient retrograde transport of BMP signaling endosomes into motoneuron nuclei. PMID:23840387

  3. Late-onset motoneuron disease caused by a functionally modified AMPA receptor subunit.

    PubMed

    Kuner, Rohini; Groom, Anthony J; Bresink, Iris; Kornau, Hans-Christian; Stefovska, Vanya; Müller, Gerald; Hartmann, Bettina; Tschauner, Karsten; Waibel, Stefan; Ludolph, Albert C; Ikonomidou, Chrysanthy; Seeburg, Peter H; Turski, Lechoslaw

    2005-04-19

    Amyotrophic lateral sclerosis (ALS) is a devastating disorder of the central nervous system in middle and old age that leads to progressive loss of spinal motoneurons. Transgenic mice overexpressing mutated human Cu(2+)/Zn(2+) superoxide dismutase 1 (SOD1) reproduce clinical features of the familial form of ALS. However, changes in SOD1 activity do not correlate with severity of motor decline in sporadic cases, indicating that targets unrelated to superoxide metabolism contribute to the pathogenesis of the disease. We show here that transgenic expression in mice of GluR-B(N)-containing L-alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionate (AMPA) receptors with increased Ca(2+) permeability leads to late-onset degeneration of neurons in the spinal cord and decline of motor functions. Neuronal death progresses over the entire lifespan but manifests clinically in late adulthood, resembling the course of a slow neurodegenerative disorder. Additional transgenic expression of mutated human SOD1 accelerates disease progression, aggravates the severity of motor decline, and decreases survival. These observations link persistently elevated Ca(2+) influx through AMPA channels with progressive motor decline and late-onset degeneration of spinal motoneurons, indicating that functionally altered AMPA channels may be causally related to pathogenesis of sporadic ALS in humans. PMID:15827116

  4. Late-onset motoneuron disease caused by a functionally modified AMPA receptor subunit

    PubMed Central

    Kuner, Rohini; Groom, Anthony J.; Bresink, Iris; Kornau, Hans-Christian; Stefovska, Vanya; Müller, Gerald; Hartmann, Bettina; Tschauner, Karsten; Waibel, Stefan; Ludolph, Albert C.; Ikonomidou, Chrysanthy; Seeburg, Peter H.; Turski, Lechoslaw

    2005-01-01

    Amyotrophic lateral sclerosis (ALS) is a devastating disorder of the central nervous system in middle and old age that leads to progressive loss of spinal motoneurons. Transgenic mice overexpressing mutated human Cu2+/Zn2+ superoxide dismutase 1 (SOD1) reproduce clinical features of the familial form of ALS. However, changes in SOD1 activity do not correlate with severity of motor decline in sporadic cases, indicating that targets unrelated to superoxide metabolism contribute to the pathogenesis of the disease. We show here that transgenic expression in mice of GluR-B(N)-containing l-α-amino-3-hydroxy-5-methylisoxazole-4-proprionate (AMPA) receptors with increased Ca2+ permeability leads to late-onset degeneration of neurons in the spinal cord and decline of motor functions. Neuronal death progresses over the entire lifespan but manifests clinically in late adulthood, resembling the course of a slow neurodegenerative disorder. Additional transgenic expression of mutated human SOD1 accelerates disease progression, aggravates the severity of motor decline, and decreases survival. These observations link persistently elevated Ca2+ influx through AMPA channels with progressive motor decline and late-onset degeneration of spinal motoneurons, indicating that functionally altered AMPA channels may be causally related to pathogenesis of sporadic ALS in humans. PMID:15827116

  5. Depletion of TDP-43 affects Drosophila motoneurons terminal synapsis and locomotive behavior.

    PubMed

    Feiguin, Fabian; Godena, Vinay K; Romano, Giulia; D'Ambrogio, Andrea; Klima, Raffaella; Baralle, Francisco E

    2009-05-19

    Pathological modifications in the highly conserved and ubiquitously expressed heterogeneous ribonucleoprotein TDP-43 were recently associated to neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), a late-onset disorder that affects predominantly motoneurons [Neumann, M. et al. (2006) Ubiquitinated TDP-43 in frontotemporal lobar degeneration and amyotrophic lateral sclerosis. Science 314, 130-133, Sreedharan, J. et al. (2008) TDP-43 mutations in familial and sporadic amyotrophic lateral sclerosis. Science 319, 1668-1672, Kabashi, E. et al. (2008) TARDBP mutations in individuals with sporadic and familial amyotrophic lateral sclerosis. Nat. Genet. 40, 572-574]. However, the function of TDP-43 in vivo is unknown and a possible direct role in neurodegeneration remains speculative. Here, we report that flies lacking Drosophila TDP-43 appeared externally normal but presented deficient locomotive behaviors, reduced life span and anatomical defects at the neuromuscular junctions. These phenotypes were rescued by expression of the human protein in a restricted group of neurons including motoneurons. Our results demonstrate the role of this protein in vivo and suggest an alternative explanation to ALS pathogenesis that may be more due to the lack of TDP 43 function than to the toxicity of the aggregates. PMID:19379745

  6. Neuropathology in respiratory-related motoneurons in young Pompe (Gaa−/−) mice

    PubMed Central

    Turner, Sara M.F.; Hoyt, Aaron K.; ElMallah, Mai K.; Falk, Darin J.; Byrne, Barry J.; Fuller, David D.

    2016-01-01

    Respiratory and/or lingual dysfunction are among the first motor symptoms in Pompe disease, a disorder resulting from absence or dysfunction of the lysosomal enzyme acid α-glucosidase (GAA). Here, we histologically evaluated the medulla, cervical and thoracic spinal cords in 6 weeks old asymptomatic Pompe (Gaa−/−) mice to determine if neuropathology in respiratory motor regions has an early onset. Periodic acid-Schiff (PAS) staining indicated glycogen accumulation was exclusively occurring in Gaa−/− hypoglossal, mid-cervical and upper thoracic motoneurons. Markers of DNA damage (Tunel) and ongoing apoptosis (Cleaved Caspase 3) did not co-localize with PAS staining, but were prominent in a medullary region which included the nucleus tractus solitarius, and also in the thoracic spinal dorsal horn. We conclude that respiratory-related motoneurons are particularly susceptible to GAA deficiency and that neuronal glycogen accumulation and neurodegeneration may occur independently in early stage disease. The data support early therapeutic intervention in Pompe disease. PMID:26921786

  7. Requirement of enhanced Survival Motoneuron protein imposed during neuromuscular junction maturation

    PubMed Central

    Kariya, Shingo; Obis, Teresa; Garone, Caterina; Akay, Turgay; Sera, Fusako; Iwata, Shinichi; Homma, Shunichi; Monani, Umrao R.

    2014-01-01

    Spinal muscular atrophy is a common motor neuron disease caused by low survival motoneuron (SMN), a key protein in the proper splicing of genes. Restoring the protein is therefore a promising therapeutic strategy. Implementation of this strategy, however, depends on defining the temporal requirements for SMN. Here, we used controlled knockdown of SMN in transgenic mice to determine the precise postnatal stage requirements for this protein. Reducing SMN in neonatal mice resulted in a classic SMA-like phenotype. Unexpectedly, depletion of SMN in adults had relatively little effect. Insensitivity to low SMN emerged abruptly at postnatal day 17, which coincided with establishment of the fully mature neuromuscular junction (NMJ). Mature animals depleted of SMN eventually exhibited evidence of selective neuromuscular pathology that was made worse by traumatic injury. The ability to regenerate the mature NMJ in aged or injured SMN-depleted mice was grossly impaired, a likely consequence of the inability to meet the surge in demand for motoneuronal SMN that was seen in controls. Our results demonstrate that relative maturity of the NMJ determines the temporal requirement for the SMN protein. These observations suggest that the use of potent but potentially deleterious SMN-enhancing agents could be tapered in human patients once the neuromuscular system matures and reintroduced as needed to enhance SMN for remodeling aged or injured NMJs. PMID:24463453

  8. Experimental and clinical evidence for the protective role of progesterone in motoneuron degeneration and neuroinflammation.

    PubMed

    Gonzalez Deniselle, M C; Garay, L; Meyer, M; Gargiulo-Monachelli, G; Labombarda, F; Gonzalez, S; Guennoun, R; Schumacher, M; De Nicola, Alejandro F

    2011-10-01

    Far beyond its role in reproduction, progesterone exerts neuro-protective, promyelinating, and anti-inflammatory effects in the nervous system. These effects are amplified under pathological conditions, implying that changes of the local environment sensitize nervous tissues to steroid therapy. The present survey covers our results of progesterone neuroprotection in a motoneuron neurodegeneration model and a neuroinflammation model. In the degenerating spinal cord of the Wobbler mouse, progesterone reverses the impaired expression of neurotrophins, increases enzymes of neurotransmission and metabolism, prevents oxidative damage of motoneurons and their vacuolar degeneration (paraptosis), and attenuates the development of mitochondrial abnormalities. After long-term treatment, progesterone also increases muscle strength and the survival of Wobbler mice. Subsequently, this review describes the effects of progesterone in mice with induced experimental autoimmune encephalomyelitis (EAE), a commonly used model of multiple sclerosis. In EAE mice, progesterone attenuates the clinical severity, decreases demyelination and neuronal dysfunction, increases axonal counts, reduces the formation of amyloid precursor protein profiles, and decreases the aberrant expression of growth-associated proteins. These actions of progesterone may be due to multiple mechanisms, considering that classic nuclear receptors, extranuclear receptors, and membrane receptors are all expressed in the spinal cord. Although many aspects of progesterone action in humans remain unsolved, data provided by experimental models makes getting to this objective closer than previously expected. PMID:25961276

  9. Dendrites are dispensable for basic motoneuron function but essential for fine tuning of behavior

    PubMed Central

    Ryglewski, Stefanie; Kadas, Dimitrios; Hutchinson, Katie; Schuetzler, Natalie; Vonhoff, Fernando; Duch, Carsten

    2014-01-01

    Dendrites are highly complex 3D structures that define neuronal morphology and connectivity and are the predominant sites for synaptic input. Defects in dendritic structure are highly consistent correlates of brain diseases. However, the precise consequences of dendritic structure defects for neuronal function and behavioral performance remain unknown. Here we probe dendritic function by using genetic tools to selectively abolish dendrites in identified Drosophila wing motoneurons without affecting other neuronal properties. We find that these motoneuron dendrites are unexpectedly dispensable for synaptic targeting, qualitatively normal neuronal activity patterns during behavior, and basic behavioral performance. However, significant performance deficits in sophisticated motor behaviors, such as flight altitude control and switching between discrete courtship song elements, scale with the degree of dendritic defect. To our knowledge, our observations provide the first direct evidence that complex dendrite architecture is critically required for fine-tuning and adaptability within robust, evolutionarily constrained behavioral programs that are vital for mating success and survival. We speculate that the observed scaling of performance deficits with the degree of structural defect is consistent with gradual increases in intellectual disability during continuously advancing structural deficiencies in progressive neurological disorders. PMID:25453076

  10. Behavioral state-specific inhibitory postsynaptic potentials impinge on cat lumbar motoneurons during active sleep.

    PubMed

    Morales, F R; Boxer, P; Chase, M H

    1987-11-01

    High-gain intracellular records were obtained from lumbar motoneurons in intact, undrugged cats during naturally occurring states of wakefulness, quiet sleep, and active sleep. Spontaneous, discrete, inhibitory postsynaptic potentials (IPSPs) were found to impinge on lumbar motoneurons during all states of sleep and wakefulness. IPSPs which occurred during wakefulness and quiet sleep were of relatively low amplitude and had a low frequency of occurrence. During the state of active sleep there occurred a great increase in inhibitory input. This was the result of the appearance of large-amplitude IPSPs and of an increase in the frequency of low-amplitude IPSPs which were indistinguishable from those recorded during wakefulness and quiet sleep. In addition to a difference in amplitude, the time course of the large IPSPs recorded during active sleep further differentiated them from the smaller IPSPs recorded during wakefulness, quiet sleep, and active sleep; i.e., their rise-time and half-width were of longer duration and their rate-of-rise was significantly faster. We suggest that the large, active sleep-specific IPSPs reflect the activity of a group of inhibitory interneurons which are inactive during wakefulness and quiet sleep and which discharge during active sleep. These as yet unidentified interneurons would then serve as the last link in the brain stem-spinal cord inhibitory system which is responsible for producing muscle atonia during the state of active sleep. PMID:3666087

  11. Fast axonal transport of labeled proteins in motoneurons of exercise-trained rats

    SciTech Connect

    Jasmin, B.J.; Lavoie, P.A.; Gardiner, P.F.

    1988-12-01

    In this study, the fast orthograde axonal transport of radiolabeled proteins was measured to determine the effects of endurance-running training on transport velocity and amounts of transported proteins in rat sciatic motoneurons. Female rats were subjected to a progressive running-training program for 10-12 wk. Twenty-four hours after the last training session, rats underwent right L4-L5 dorsal root ganglionectomy. The next day, 20 microCi of (3H)leucine was injected bilaterally in the vicinity of the motoneuronal cell bodies supplying the sciatic nerve, to study axonal transport parameters. Results showed that peak and average transport velocities of labeled proteins were significantly (P less than 0.05) increased by 22 and 29%, respectively, in the deafferented nerves of the runners as compared with controls. Moreover, the amount of total transported protein-bound radioactivity was increased in both left (40%) and right (37%) sciatic nerves of the runners. An exhaustive exercise session reduced (P less than 0.05) peak displacement (8%) and total transported protein-bound radioactivity (36%) in the sciatic nerves of control rats, whereas no changes were noticed in trained animals. The data suggest that chronic endurance running induces significant adaptations in the fast axonal transport of labeled proteins.

  12. Perineal striated muscles: Anatomy, spinal motoneurons, and participation on copulatory behavior in male rabbits (Oryctolagus cuniculus).

    PubMed

    Zempoalteca, R; Lucio, R A; Eguibar, J R

    2008-09-01

    Despite the importance of rabbits in reproductive studies, little information is available on the anatomy and participation of the striated-perineal muscles in male copulatory behavior. In our study, we describe the gross anatomy of two striated-perineal muscles: the ischiocavernosus (ICm) and the bulbospongiosus (BSm). Both muscles have their origin at the ischiadic arc, but the ICm is inserted into the penile crura and the BSm onto the ligamentum suspensorium of the penis. The motoneurons of both muscles were identified using retrograde labeling with horseradish peroxidase coupled to wheat-germ agglutinin. Motoneurons were dispersed in the lower-lumbar and upper-sacral spinal-cord segments, instead of being aggregated in the neuronal nucleus as in other species: the rat, mouse, gerbil, cat, and man. Bilateral dennervation of the ICm or BSm or both in sexually experienced male rabbits did not affect copulatory variables measured at 10, 20, and 30 days after surgery. However, muscular dennervation produced extravaginal ejaculations in 42% of copulatory tests and no ejaculation in 7% of tests, although male pelvic thrusting occurred. These results suggest the participation of the ICm and BSm perineal muscles in penile orientation during copulation but not in seminal emission as described in other mammalian species. PMID:18563835

  13. Differential facilitation of high- and low-output nerve terminals from a single motoneuron.

    PubMed

    Crider, M E; Cooper, R L

    2000-03-01

    In the crayfish opener neuromuscular preparation, regional differences in synaptic transmission are observed among the terminals of a single motoneuron. With a single stimulus, the high-output terminals of the proximal region of the muscle produce a larger excitatory postsynaptic potential than do the low-output terminals of the central region of the muscle. We tested the hypothesis that the low-output terminals exhibit more facilitation than do high-output terminals for twin-pulse, train, and continuous-stimulation paradigms. Previous studies have not employed several stimulation paradigms to induce facilitation among high- and low-output terminals of a single motoneuron. We found that the high-output terminals on the proximal fibers facilitate more than the low-output terminals on the central muscle fibers, in contrast with previous studies on similar muscles. The difference in measured facilitation is dependent on the stimulation paradigm. These results are important because ultrastructural differences between these high- and low-output terminals are known and can be used for correlation with physiological measurements. Short-term facilitation is a form of short-term memory at the synaptic level, and the processes understood at the crayfish neuromuscular junction may well be applicable to all chemical synapses. PMID:10710395

  14. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint... ankle joint. The device limits translation and rotation: in one or more planes via the geometry of...

  15. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint... ankle joint. The device limits translation and rotation: in one or more planes via the geometry of...

  16. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint... ankle joint. The device limits translation and rotation: in one or more planes via the geometry of...

  17. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint... ankle joint. The device limits translation and rotation: in one or more planes via the geometry of...

  18. Use of spike triggered averaging of muscle activity to quantify inputs to motoneuron pools.

    PubMed

    Fortier, P A

    1994-07-01

    1. The goal of this study was to determine the extent to which postspike facilitation (PSpF) of electromyograms (EMGs) could be used to estimate the inputs to separate motoneuron pools, under conditions where there was wide variability in the parameters of muscle activity. These parameters included cancellation of motor unit action potentials (MUAPs), variations in EMG noise, and changes in MUAP amplitude and duration. A systematic series of computer simulations with increasing complexity were used to achieve this goal. The initial simulations (model I) included a premotoneuronal (PreM) cell connected to a single postsynaptic motoneuron (Mn), which in turn projected to a muscle. The next simulations (model II) included other target motoneurons with their efferents each projecting to separate muscles. The last simulations (model III) included more than one postsynaptic motoneuron per Mn-pool, as is the case in mammalian neuromuscular systems. 2. A sample simulation (model I) was performed to determine if the PreM-evoked effects were within physiologically observed values. A cross-correlogram (XC) calculated from a PreM cell and its target Mn, receiving a PreM-evoked excitatory postsynaptic potential (EPSP) of 0.5 mV, produced a XC peak area of 0.04 Mn-spikes/PreM-trigger. The PSpF of EMG activity evoked by this PreM cell had a mean percent increase of 4.6% (MPI = mean bin amplitude of PSpF above baseline/mean baseline level x 100). These XC and PSpF values were within the range of values previously obtained from animal experiments. 3. The magnitude of MUAP cancellation in the EMG was tested by calculating two spike-triggered averages (SpTAs) of EMGs from Mn-triggers (not PreM-triggers as in the other SpTAs): one using typical bipolar MUAPs and another using their rectified counterpart of only positive polarity to eliminate the possibility of MUAP cancellation. The PSpF calculated from bipolar spikes was 24.8% smaller than the one calculated using unipolar spikes

  19. Imaging evaluation of traumatic ligamentous injuries of the ankle and foot.

    PubMed

    Nazarenko, Anna; Beltran, Luis S; Bencardino, Jenny T

    2013-05-01

    Sports ankle injuries are very common worldwide. In the United States, it is estimated that 2 million acute ankle sprains occur each year, averaging to $318 to $914 per sprain. Magnetic resonance imaging is excellent for depicting normal ankle anatomy and can elegantly demonstrate ligamentous injuries of the ankle and associated conditions after ankle sprain. This article encompasses epidemiology, biomechanics, normal anatomy, and pathologic conditions of the ankle and foot ligaments. The specific ligaments discussed include the syndesmotic ligaments, lateral ligament complex of the ankle, deltoid ligament, spring ligament, ligaments of the sinus tarsi, and the Lisfranc ligament. PMID:23622094

  20. Naloxone reduces the amplitude of IPSPs evoked in lumbar motoneurons by reticular stimulation during carbachol-induced motor inhibition.

    PubMed

    Xi, M C; Liu, R H; Yamuy, J; Morales, F R; Chase, M H

    1999-02-20

    During active sleep or carbachol-induced motor inhibition, electrical stimulation of the medullary nucleus reticularis gigantocellularis (NRGc) evoked large amplitude, glycinergic inhibitory postsynaptic potentials (IPSPs) in cat motoneurons. The present study was directed to determine whether these IPSPs, that are specific to the state of active sleep, are modulated by opioid peptides. Accordingly, intracellular recordings were obtained from lumbar motoneurons of acute decerebrate cats during carbachol-induced motor inhibition while an opiate receptor antagonist, naloxone, was microiontophoretically released next to the recorded cells. Naloxone reversibly reduced by 26% the mean amplitude of NRGc-evoked IPSPs (1.9+/-0.2 mV (S.E.M.) vs. 1.4+/-0.2 mV; n=11, control and naloxone, respectively, p<0.05), but had no effect on the other waveform parameters of these IPSPs (e.g., latency-to-onset, latency-to-peak, duration, etc.). The mean resting membrane potential, input resistance and membrane time constant of motoneurons following naloxone ejection were not statistically different from those of the control. These data indicate that opioid peptides have a modulatory effect on NRGc-evoked IPSPs during carbachol-induced motor inhibition. We therefore suggest that endogenous opioid peptides may act as neuromodulators to regulate inhibitory glycinergic synaptic transmission at motoneurons during active sleep. PMID:10082872

  1. Selective Requirement for Maintenance of Synaptic Contacts onto Motoneurons by Target-Derived trkB Receptors

    PubMed Central

    2016-01-01

    Synaptic contacts onto motoneurons were studied in mice in which the gene for the trkB neurotrophin receptor was knocked out selectively in a subset of spinal motoneurons. The extent of contacts by structures immunoreactive for either of two different vesicular glutamate transporters (VGLUT1 and VGLUT2), the vesicular GABA transporter, or glutamic acid decarboxylase 67 (GAD67) with the somata of motoneurons, was studied in wild type and trkB knockout cells in tamoxifen treated male and female SLICK-trkB−/− mice. Selective knockout of the trkB gene resulted in a marked reduction in contacts made by VGLUT2- and GAD67-immunoreactive structures in both sexes and a significant reduction in contacts containing only glycine in male mice. No reduction was found for glycinergic contacts in female mice or for VGLUT1 immunoreactive contacts in either sex. Signaling through postsynaptic trkB receptors is considered to be an essential part of a cellular mechanism for maintaining the contacts of some, but not all, synaptic contacts onto motoneurons. PMID:27433358

  2. Localisation of motoneurons supplying the extra-ocular muscles of the rat using horseradish peroxidase and fluorescent double labelling.

    PubMed Central

    Labandeira Garcia, J L; Gomez Segade, L A; Suarez Nuñez, J M

    1983-01-01

    This paper describes a qualitative and quantitative investigation into the location of the motoneurons innervating the extra-ocular muscles of the rat. Injections of horseradish peroxidase, bisbenzimide, propidium iodide and DAPI-primuline were made either in one or simultaneously in two muscles. Unlike those of the cat, rabbit and monkey, the motoneurons which make up the oculomotor nucleus of the rat are not arranged in spatially separate subgroups belonging each to its corresponding extra-ocular muscle, but instead allow a high degree of superposition among the motor pools which they compose. The motoneurons innervating the lateral rectus and inferior oblique muscles are all homolateral; those of the medial and inferior rectus muscles are mainly homolateral with a few contralateral exceptions; and those of the superior rectus, levator palpebrae and superior oblique muscles are mainly contralateral with a small minority of homolateral exceptions. As well as from the main motor pools with which they are associated, the medial rectus, inferior rectus, superior rectus, levator palpebrae, superior oblique and lateral rectus muscles all receive innervation from motoneurons lying among the fibres of the fasciculus longitudinalis medialis. All these observations are supported by quantitative data. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:6195140

  3. Bone alterations are associated with ankle osteoarthritis joint pain

    PubMed Central

    Nakamura, Yukio; Uchiyama, Shigeharu; Kamimura, Mikio; Komatsu, Masatoshi; Ikegami, Shota; Kato, Hiroyuki

    2016-01-01

    The etiology of ankle osteoarthritis (OA) is largely unknown. We analyzed 24 ankle OA of 21 patients diagnosed by plain radiographs using magnetic resonance imaging (MRI). Ankle joint pain disappeared in 22 out of 24 joints by conservative treatment. MRI bone signal changes in and around the ankle joints were observed in 22 of 24 joints. Bone signal changes along the joint line were seen in 10 of 11 joints as a Kellgren-Lawrence (KL) grade of II to IV. Such signal changes were witnessed in only 4 of 13 joints with KL grade 0 or I. In the talocrural joint, bone alterations occurred in both tibia and talus bones through the joint line in cases of KL grade III or IV, while focal bone alterations were present in the talus only in KL grade I or II cases. Sixteen of 24 joints exhibited intraosseous bone signal changes, which tended to correspond to joint pain of any ankle OA stage. Our results suggest that bone alterations around the ankle joint might be one of the etiologies of OA and associated with ankle joint pain. PMID:26776564

  4. Ankle motion after external fixation of tibial fractures.

    PubMed Central

    Taylor, G J; Allum, R L

    1988-01-01

    Loss of ankle movement is a complication of severe tibial fractures. This can be exacerbated if the foot is allowed to drop into equinus, particularly when an external fixator is employed. The range of ankle motion following external fixation of tibial fractures as compared to the opposite normal ankle was studied in 40 of 55 patients treated over a ten-year period. Nine were excluded due to other causes of ankle stiffness, leaving 31 cases for analysis. The mean follow up was 2 years 7 months (range 1 year to 8 years 3 months), and union had occurred by a mean of 35 weeks (range 9-100 weeks). The mean loss of ankle movement was 8 degrees of plantar-flexion and 12 degrees of dorsiflexion (overall loss 20 degrees), the difference between the two being highly significant (P greater than 0.001, t test). Loss of ankle motion closely paralleled the degree of soft tissue trauma, being 6 degrees for closed fractures and 22 degrees for open fractures (0.05 greater than P greater than 0.02). Ankle function is therefore at risk when a severe tibial fracture is treated by external fixation, and appropriate measures should be taken to preserve movement and prevent an equinus contracture. Images Figure 1. Figure 2. Figure 3. PMID:3343667

  5. Managing ankle ligament sprains and tears: current opinion

    PubMed Central

    McGovern, Ryan P; Martin, RobRoy L

    2016-01-01

    The purpose of this paper is to present a current review of pathoanatomical features, differential diagnosis, objective assessment, intervention, and clinical course associated with managing lateral ankle ligament sprains. Proper diagnosis and identification of affected structures should be obtained through history and objective assessment. From this information, an individualized evidence-based intervention plan can be developed to enable recovery while decreasing the risk of reinjury. An appropriate evaluation is needed not only to determine the correct diagnosis but also to allow for grading and determining the prognosis of the injury in those with an acute lateral ankle sprain. Examination should include an assessment of impairments as well as a measure of activity and participation. Evidence-based interventions for those with an acute lateral ankle sprain should include weight bearing with bracing, manual therapy, progressive therapeutic exercises, and cryotherapy. For those with chronic ankle instability (CAI), interventions should include manual therapy and a comprehensive rehabilitation program. It is essential to understand the normal clinical course for athletes who sustain a lateral ankle sprain as well as risk factors for an acute injury and CAI. Risk factors for both an acute lateral ankle sprain and CAI include not using an external support and not participating in an appropriate exercise program. Incorporating the latest evidence-based rehabilitation techniques provides the best course of treatment for athletes with an acute ankle sprain or CAI. PMID:27042147

  6. The Anatomy and Mechanisms of Syndesmotic Ankle Sprains

    PubMed Central

    Floyd, R. T.

    2001-01-01

    Objective: To present a comprehensive review of the anatomy, biomechanics, and mechanisms of tibiofibular syndesmosis ankle sprains. Data Sources: MEDLINE (1966–1998) and CINAHL (1982–1998) searches using the key words syndesmosis, tibiofibular, ankle injuries, and ankle injuries–etiology. Data Synthesis: Stability of the distal tibiofibular syndesmosis is necessary for proper functioning of the ankle and lower extremity. Much of the ankle's stability is provided by the mortise formed around the talus by the tibia and fibula. The anterior and posterior inferior tibiofibular ligaments, the interosseous ligament, and the interosseous membrane act to statically stabilize the joint. During dorsiflexion, the wider portion anteriorly more completely fills the mortise, and contact between the articular surfaces is maximal. The distal structures of the lower leg primarily prevent lateral displacement of the fibula and talus and maintain a stable mortise. A variety of mechanisms individually or combined can cause syndesmosis injury. The most common mechanisms, individually and particularly in combination, are external rotation and hyperdorsiflexion. Both cause a widening of the mortise, resulting in disruption of the syndesmosis and talar instability. Conclusions and Recommendation: Syndesmosis ankle injuries are less common than lateral ankle injuries, are difficult to evaluate, have a long recovery period, and may disrupt normal joint functioning. To effectively evaluate and treat this injury, clinicians should have a full understanding of the involved structures, functional anatomy, and etiologic factors. PMID:16404437

  7. Multivariable Dynamic Ankle Mechanical Impedance With Active Muscles

    PubMed Central

    Lee, Hyunglae; Krebs, Hermano Igo; Hogan, Neville

    2015-01-01

    Multivariable dynamic ankle mechanical impedance in two coupled degrees-of-freedom (DOFs) was quantified when muscles were active. Measurements were performed at five different target activation levels of tibialis anterior and soleus, from 10% to 30% of maximum voluntary contraction (MVC) with increments of 5% MVC. Interestingly, several ankle behaviors characterized in our previous study of the relaxed ankle were observed with muscles active: ankle mechanical impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness; stiffness was greater in the sagittal plane than in the frontal plane at all activation conditions for all subjects; and the coupling between dorsiflexion–plantarflexion and inversion–eversion was small—the two DOF measurements were well explained by a strictly diagonal impedance matrix. In general, ankle stiffness increased linearly with muscle activation in all directions in the 2-D space formed by the sagittal and frontal planes, but more in the sagittal than in the frontal plane, resulting in an accentuated “peanut shape.” This characterization of young healthy subjects’ ankle mechanical impedance with active muscles will serve as a baseline to investigate pathophysiological ankle behaviors of biomechanically and/or neurologically impaired patients. PMID:25203497

  8. Managing ankle ligament sprains and tears: current opinion.

    PubMed

    McGovern, Ryan P; Martin, RobRoy L

    2016-01-01

    The purpose of this paper is to present a current review of pathoanatomical features, differential diagnosis, objective assessment, intervention, and clinical course associated with managing lateral ankle ligament sprains. Proper diagnosis and identification of affected structures should be obtained through history and objective assessment. From this information, an individualized evidence-based intervention plan can be developed to enable recovery while decreasing the risk of reinjury. An appropriate evaluation is needed not only to determine the correct diagnosis but also to allow for grading and determining the prognosis of the injury in those with an acute lateral ankle sprain. Examination should include an assessment of impairments as well as a measure of activity and participation. Evidence-based interventions for those with an acute lateral ankle sprain should include weight bearing with bracing, manual therapy, progressive therapeutic exercises, and cryotherapy. For those with chronic ankle instability (CAI), interventions should include manual therapy and a comprehensive rehabilitation program. It is essential to understand the normal clinical course for athletes who sustain a lateral ankle sprain as well as risk factors for an acute injury and CAI. Risk factors for both an acute lateral ankle sprain and CAI include not using an external support and not participating in an appropriate exercise program. Incorporating the latest evidence-based rehabilitation techniques provides the best course of treatment for athletes with an acute ankle sprain or CAI. PMID:27042147

  9. Immunohistochemical study of motoneurons in lumbar spinal cord of c57black/6 mice after 30-days space flight

    NASA Astrophysics Data System (ADS)

    Tyapkina, Oksana; Islamov, Rustem; Nurullin, Leniz; Petrov, Konstantin.; Rezvyakov, Pavel; Nikolsky, Evgeny

    To investigate mechanisms of hypogravity motor syndrome development the immunoexpression of heat shock proteins (Hsp27 and Hsp70), proteins of synaptic transmission (Synaptophysin and PSD95) and neuroprotective proteins (VEGF and Flt-1) in motoneurons of lumbar spinal cord in c57black/6 control mice (n=2) and after 30-days space flight (n=2) was studied. For a quantitative assessment of target proteins level in motoneurons frozen cross sections of lumbar spinal cord were underwent to immunohistochemical staining. Primary antibodies against VEGF, Flt-1, Hsp27 and Hsp70 (SantaCruz Biotechnology, inc. USA), against Synaptophysin and PSD95 (Abcam plc, UK) were visualized by streptavidin-biotin method. Images of spinal cords were received using OlympusBX51WI microscope with AxioCamMRm camera (CarlZeiss, Germany) and the AxioVisionRel. 4.6.3 software (CarlZeiss, Germany). The digitized data were analyzed using ImageJ 1.43 software (NIH, the USA). Quantitively, protein level in motoneurons was estimated by the density of immunoprecipitation. Results of research have not revealed any reliable changes in the immunnoexpression of vascular endothelial growth factor (VEGF) and its Flt-1 receptor in motoneurons of lumbar spinal cord in control and in mice after 30-day space flight. Studying of heat shock proteins, such as Hsp27 and Hsp70, revealed the decrease in level of these proteins immunoexpression in motoneurons of mice from flight group by 15% and 10%, respectively. Some decrease in level of immunnoexpression of presynaptic membrane proteins (synaptophysin, by 21%) and proteins of postsynaptic area (PSD95, by 55%) was observed after space flight. The data obtained testify to possible changes in a functional state (synaptic activity and stress resistance) of motoneurons of lumbar spinal cord in mice after space flight. Thus, we obtained new data on involvement of motoneurons innervating skeletal muscles in development of hypogravity motor syndrome. Research was supported

  10. Voltage-gated calcium channels are abnormal in cultured spinal motoneurons in the G93A-SOD1 transgenic mouse model of ALS.

    PubMed

    Chang, Qing; Martin, Lee J

    2016-09-01

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive loss of motoneurons. Hyperexcitability and excitotoxicity have been implicated in the early pathogenesis of ALS. Studies addressing excitotoxic motoneuron death and intracellular Ca(2+) overload have mostly focused on Ca(2+) influx through AMPA glutamate receptors. However, intrinsic excitability of motoneurons through voltage-gated ion channels may also have a role in the neurodegeneration. In this study we examined the function and localization of voltage-gated Ca(2+) channels in cultured spinal cord motoneurons from mice expressing a mutant form of human superoxide dismutase-1 with a Gly93→Ala substitution (G93A-SOD1). Using whole-cell patch-clamp recordings, we showed that high voltage activated (HVA) Ca(2+) currents are increased in G93A-SOD1 motoneurons, but low voltage activated Ca(2+) currents are not affected. G93A-SOD1 motoneurons also have altered persistent Ca(2+) current mediated by L-type Ca(2+) channels. Quantitative single-cell RT-PCR revealed higher levels of Ca1a, Ca1b, Ca1c, and Ca1e subunit mRNA expression in G93A-SOD1 motoneurons, indicating that the increase of HVA Ca(2+) currents may result from upregulation of Ca(2+) channel mRNA expression in motoneurons. The localizations of the Ca1B N-type and Ca1D L-type Ca(2+) channels in motoneurons were examined by immunocytochemistry and confocal microscopy. G93A-SOD1 motoneurons had increased Ca1B channels on the plasma membrane of soma and dendrites. Ca1D channels are similar on the plasma membrane of soma and lower on the plasma membrane of dendrites of G93A-SOD1 motoneurons. Our study demonstrates that voltage-gated Ca(2+) channels have aberrant functions and localizations in ALS mouse motoneurons. The increased HVA Ca(2+) currents and PCCa current could contribute to early pathogenesis of ALS. PMID:27151771

  11. Ultrasound-guided interventions of the foot and ankle.

    PubMed

    Yablon, Corrie M

    2013-02-01

    Ultrasound (US) provides excellent delineation of tendons and ligaments in the foot and ankle and provides real-time visualization of a needle during interventions, yielding greater accuracy and efficacy than the traditional blind approach using anatomical landmarks. For this reason, US is rapidly gaining acceptance as the preferred modality for guiding interventions in the foot and ankle where the anatomy is complex, neurovascular structures should be identified, and precise technique is demanded. In the foot and ankle, US is especially useful to guide tendon sheath, bursal, and Achilles paratenon injections, Morton neuroma injections, plantar fascial injections, and joint aspirations and injections. PMID:23487336

  12. Diabetic charcot neuroarthropathy of the foot and ankle with osteomyelitis.

    PubMed

    Ramanujam, Crystal L; Stapleton, John J; Zgonis, Thomas

    2014-10-01

    One of the most devastating foot and/or ankle complications in the diabetic population with peripheral neuropathy is the presence of Charcot neuroarthropathy (CN). In recent years, diabetic limb salvage has been attempted more frequently as opposed to major lower extremity amputation for CN of the foot and ankle with ulceration and/or deep infection. Treatment strategies for osteomyelitis in the diabetic population have evolved. This article reviews some of the most common surgical strategies recommended for the diabetic patient with CN of the foot and/or ankle and concomitant osteomyelitis. PMID:25281510

  13. Ankle-foot orthosis function in low-level myelomeningocele.

    PubMed

    Hullin, M G; Robb, J E; Loudon, I R

    1992-01-01

    Six children with low-level myelomeningocele underwent gait analysis. All showed excessive ankle dorsiflexion and knee flexion when walking barefoot. A rigid thermoplastic ankle-foot orthosis (AFO) improved gait by preventing ankle dorsiflexion and reducing knee flexion. Biomechanically, the AFO caused a reduction in external knee moment by aligning the knee with the ground reaction force. Small changes in the foot-shank angle of the orthosis had profound effects on knee mechanics. Knee hyperextension could be controlled by a rocker sole. Kinetic gait analysis permits understanding of the biomechanical effects of orthoses. PMID:1613099

  14. Return to Play Following Ankle Sprain and Lateral Ligament Reconstruction.

    PubMed

    Shawen, Scott B; Dworak, Theodora; Anderson, Robert B

    2016-10-01

    Ankle sprains are the most common musculoskeletal injury occurring during athletics. Proper initial treatment with supportive pain control, limited immobilization, early return to weight bearing and range of motion, and directed physical therapy are essential for preventing recurrent injury. Reconstruction of the lateral ligaments is indicated for patients with continued instability and dysfunction despite physical therapy. Return to athletic activity should be reserved for athletes who have regained strength, proprioception, and range of motion of the injured ankle. Athletes with a history of an ankle sprain should be prophylactically braced or tapped to reduce risk of recurrent injury. PMID:27543408

  15. Seasonality of Ankle Swelling: Population Symptom Reporting Using Google Trends.

    PubMed

    Liu, Fangwei; Allan, G Michael; Korownyk, Christina; Kolber, Michael; Flook, Nigel; Sternberg, Harvey; Garrison, Scott

    2016-07-01

    In our experience, complaints of ankle swelling are more common in summer, typically from patients with no obvious cardiovascular disease. Surprisingly, this observation has never been reported. To objectively establish this phenomenon, we sought evidence of seasonality in the public's Internet searches for ankle swelling. Our data, obtained from Google Trends, consisted of all related Google searches in the United States from January 4, 2004, to January 26, 2016. Consistent with our expectations and confirmed by similar data for Australia, Internet searches for information on ankle swelling are highly seasonal (highest in midsummer), with seasonality explaining 86% of search volume variability. PMID:27401424

  16. Contribution of intrinsic motoneuron properties to discharge hysteresis and its estimation based on paired motor unit recordings: a simulation study.

    PubMed

    Powers, Randall K; Heckman, C J

    2015-07-01

    Motoneuron activity is strongly influenced by the activation of persistent inward currents (PICs) mediated by voltage-gated sodium and calcium channels. However, the amount of PIC contribution to the activation of human motoneurons can only be estimated indirectly. Simultaneous recordings of pairs of motor units have been used to provide an estimate of the PIC contribution by using the firing rate of the lower threshold unit to provide an estimate of the common synaptic drive to both units, and the difference in firing rate (ΔF) of this lower threshold unit at recruitment and de-recruitment of the higher threshold unit to estimate the PIC contribution to activation of the higher threshold unit. It has recently been suggested that a number of factors other than PIC can contribute to ΔF values, including mechanisms underlying spike frequency adaptation and spike threshold accommodation. In the present study, we used a set of compartmental models representing a sample of 20 motoneurons with a range of thresholds to investigate how several different intrinsic motoneuron properties can potentially contribute to variations in ΔF values. We drove the models with linearly increasing and decreasing noisy conductance commands of different rate of rise and duration and determined the influence of different intrinsic mechanisms on discharge hysteresis (the difference in excitatory drive at recruitment and de-recruitment) and ΔF. Our results indicate that, although other factors can contribute, variations in discharge hysteresis and ΔF values primarily reflect the contribution of dendritic PICs to motoneuron activation. PMID:25904704

  17. Motoneuronal Sema3C is essential for setting stereotyped motor tract positioning in limb-derived chemotropic semaphorins.

    PubMed

    Sanyas, Isabelle; Bozon, Muriel; Moret, Frédéric; Castellani, Valérie

    2012-10-01

    The wiring of neuronal circuits requires complex mechanisms to guide axon subsets to their specific target with high precision. To overcome the limited number of guidance cues, modulation of axon responsiveness is crucial for specifying accurate trajectories. We report here a novel mechanism by which ligand/receptor co-expression in neurons modulates the integration of other guidance cues by the growth cone. Class 3 semaphorins (Sema3 semaphorins) are chemotropic guidance cues for various neuronal projections, among which are spinal motor axons navigating towards their peripheral target muscles. Intriguingly, Sema3 proteins are dynamically expressed, forming a code in motoneuron subpopulations, whereas their receptors, the neuropilins, are expressed in most of them. Targeted gain- and loss-of-function approaches in the chick neural tube were performed to enable selective manipulation of Sema3C expression in motoneurons. We show that motoneuronal Sema3C regulates the shared Sema3 neuropilin receptors Nrp1 and Nrp2 levels in opposite ways at the growth cone surface. This sets the respective responsiveness to exogenous Nrp1- and Nrp2-dependent Sema3A, Sema3F and Sema3C repellents. Moreover, in vivo analysis revealed a context where this modulation is essential. Motor axons innervating the forelimb muscles are exposed to combined expressions of semaphorins. We show first that the positioning of spinal nerves is highly stereotyped and second that it is compromised by alteration of motoneuronal Sema3C. Thus, the role of the motoneuronal Sema3 code could be to set population-specific axon sensitivity to limb-derived chemotropic Sema3 proteins, therefore specifying stereotyped motor nerve trajectories in their target field. PMID:22899844

  18. Weakened rate-dependent depression of Hoffmann's reflex and increased motoneuron hyperactivity after motor cortical infarction in mice

    PubMed Central

    Lee, S; Toda, T; Kiyama, H; Yamashita, T

    2014-01-01

    Abnormal reflexes associated with spasticity are considered a major determinant of motor impairments occurring after stroke; however, the mechanisms underlying post-stroke spasticity remain unclear. This may be because of the lack of suitable rodent models for studying spasticity after cortical injuries. Thus, the purpose of the present study was to establish an appropriate post-stroke spasticity mouse model. We induced photothrombotic injury in the rostral and caudal forelimb motor areas of mice and used the rate-dependent depression (RDD) of Hoffmann's reflex (H-reflex) as an indicator of spastic symptoms. To detect motoneuron excitability, we examined c-fos mRNA levels and c-Fos immunoreactivity in affected motoneurons using quantitative real-time reverse transcription PCR and immunohistochemical analysis, respectively. To confirm the validity of our model, we confirmed the effect of the anti-spasticity drug baclofen on H-reflex RDDs 1 week post stroke. We found that 3 days after stroke, the RDD was significantly weakened in the affected muscles of stroke mice compared with sham-operated mice, and this was observed for 8 weeks. The c-fos mRNA levels in affected motoneurons were significantly increased in stroke mice compared with sham-operated mice. Immunohistochemical analysis revealed a significant increase in the number of c-Fos-positive motoneurons in stroke mice compared with sham-operated mice at 1, 2, 4, and 8 weeks after stroke; however, the number of c-Fos-positive motoneurons on both sides of the brain gradually decreased over time. Baclofen treatment resulted in recovery of the weakened RDD at 1 week post stroke. Our findings suggest that this is a viable animal model of post-stroke spasticity. PMID:24434515

  19. Weakened rate-dependent depression of Hoffmann's reflex and increased motoneuron hyperactivity after motor cortical infarction in mice.

    PubMed

    Lee, S; Toda, T; Kiyama, H; Yamashita, T

    2014-01-01

    Abnormal reflexes associated with spasticity are considered a major determinant of motor impairments occurring after stroke; however, the mechanisms underlying post-stroke spasticity remain unclear. This may be because of the lack of suitable rodent models for studying spasticity after cortical injuries. Thus, the purpose of the present study was to establish an appropriate post-stroke spasticity mouse model. We induced photothrombotic injury in the rostral and caudal forelimb motor areas of mice and used the rate-dependent depression (RDD) of Hoffmann's reflex (H-reflex) as an indicator of spastic symptoms. To detect motoneuron excitability, we examined c-fos mRNA levels and c-Fos immunoreactivity in affected motoneurons using quantitative real-time reverse transcription PCR and immunohistochemical analysis, respectively. To confirm the validity of our model, we confirmed the effect of the anti-spasticity drug baclofen on H-reflex RDDs 1 week post stroke. We found that 3 days after stroke, the RDD was significantly weakened in the affected muscles of stroke mice compared with sham-operated mice, and this was observed for 8 weeks. The c-fos mRNA levels in affected motoneurons were significantly increased in stroke mice compared with sham-operated mice. Immunohistochemical analysis revealed a significant increase in the number of c-Fos-positive motoneurons in stroke mice compared with sham-operated mice at 1, 2, 4, and 8 weeks after stroke; however, the number of c-Fos-positive motoneurons on both sides of the brain gradually decreased over time. Baclofen treatment resulted in recovery of the weakened RDD at 1 week post stroke. Our findings suggest that this is a viable animal model of post-stroke spasticity. PMID:24434515

  20. Glycinergic and GABA(A)-mediated inhibition of somatic motoneurons does not mediate rapid eye movement sleep motor atonia.

    PubMed

    Brooks, Patricia L; Peever, John H

    2008-04-01

    A hallmark of rapid eye movement (REM) sleep is a potent suppression of postural muscle tone. Motor control in REM sleep is unique because it is characterized by flurries of intermittent muscle twitches that punctuate muscle atonia. Because somatic motoneurons are bombarded by strychnine-sensitive IPSPs during REM sleep, it is assumed that glycinergic inhibition underlies REM atonia. However, it has never been determined whether glycinergic inhibition of motoneurons is indeed responsible for triggering the loss of postural muscle tone during REM sleep. Therefore, we used reverse microdialysis, electrophysiology, and pharmacological and histological methods to determine whether glycinergic and/or GABA(A)-mediated neurotransmission at the trigeminal motor pool mediates masseter muscle atonia during REM sleep in rats. By antagonizing glycine and GABA(A) receptors on trigeminal motoneurons, we unmasked a tonic glycinergic/GABAergic drive at the trigeminal motor pool during waking and non-rapid eye movement (NREM) sleep. Blockade of this drive potently increased masseter muscle tone during both waking and NREM sleep. This glycinergic/GABAergic drive was immediately switched-off and converted into a phasic glycinergic drive during REM sleep. Blockade of this phasic drive potently provoked muscle twitch activity in REM sleep; however, it did not prevent or reverse REM atonia. Muscle atonia in REM even persisted when glycine and GABA(A) receptors were simultaneously antagonized and trigeminal motoneurons were directly activated by glutamatergic excitation, indicating that a powerful, yet unidentified, inhibitory mechanism overrides motoneuron excitation during REM sleep. Our data refute the prevailing hypothesis that REM atonia is caused by glycinergic inhibition. The inhibitory mechanism mediating REM atonia therefore requires reevaluation. PMID:18385312

  1. Delaying the onset of treadmill exercise following peripheral nerve injury has different effects on axon regeneration and motoneuron synaptic plasticity

    PubMed Central

    Brandt, Jaclyn; Evans, Jonathan T.; Mildenhall, Taylor; Mulligan, Amanda; Konieczny, Aimee; Rose, Samuel J.

    2015-01-01

    Transection of a peripheral nerve results in withdrawal of synapses from motoneurons. Some of the withdrawn synapses are restored spontaneously, but those containing the vesicular glutamate transporter 1 (VGLUT1), and arising mainly from primary afferent neurons, are withdrawn permanently. If animals are exercised immediately after nerve injury, regeneration of the damaged axons is enhanced and no withdrawal of synapses from injured motoneurons can be detected. We investigated whether delaying the onset of exercise until after synapse withdrawal had occurred would yield similar results. In Lewis rats, the right sciatic nerve was cut and repaired. Reinnervation of the soleus muscle was monitored until a direct muscle (M) response was observed to stimulation of the tibial nerve. At that time, rats began 2 wk of daily treadmill exercise using an interval training protocol. Both M responses and electrically-evoked H reflexes were monitored weekly for an additional seven wk. Contacts made by structures containing VGLUT1 or glutamic acid decarboxylase (GAD67) with motoneurons were studied from confocal images of retrogradely labeled cells. Timing of full muscle reinnervation was similar in both delayed and immediately exercised rats. H reflex amplitude in delayed exercised rats was only half that found in immediately exercised animals. Unlike immediately exercised animals, motoneuron contacts containing VGLUT1 in delayed exercised rats were reduced significantly, relative to intact rats. The therapeutic window for application of exercise as a treatment to promote restoration of synaptic inputs onto motoneurons following peripheral nerve injury is different from that for promoting axon regeneration in the periphery. PMID:25632080

  2. Semaphorin and neuropilin co-expression in motoneurons sets axon sensitivity to environmental semaphorin sources during motor axon pathfinding.

    PubMed

    Moret, Frédéric; Renaudot, Christelle; Bozon, Muriel; Castellani, Valérie

    2007-12-01

    Class III semaphorins (SemaIIIs) are intercellular cues secreted by surrounding tissues to guide migrating cells and axons in the developing organism. This chemotropic activity is crucial for the formation of nerves and vasculature. Intriguingly, SemaIIIs are also synthesized by neurons during axon pathfinding, but their function as intrinsic cues remains unknown. We have explored the role of Sema3A expression in motoneurons during spinal nerve development. Loss- and gain-of-function in the neural tube of the chick embryo were undertaken to target Sema3A expression in motoneurons while preserving Sema3A sources localized in peripheral tissues, known to provide important repulsive information for delineating the routes of motor axons towards their ventral or dorsal targets. Strikingly, Sema3A overexpression induced defasciculation and exuberant growth of motor axon projections into these normally non-permissive territories. Moreover, knockdown studies showed that motoneuronal Sema3A is required for correct spinal nerve compaction and dorsal motor axon extension. Further analysis of Sema3A gain- and loss-of-function in ex vivo models revealed that Sema3A in motoneurons sets the level of sensitivity of their growth cones to exogenous Sema3A exposure. This regulation is associated with post-transcriptional and local control of the availability of the Sema3A receptor neuropilin 1 at the growth cone surface. Thus, by modulating the strength of Sema3A-mediated environmental repulsive constraints, Sema3A in motoneurons enables axons to extend more or less far away from these repulsive sources. Such interplay between intrinsic and extrinsic Sema3A may represent a fundamental mechanism in the accurate specification of axon pathways. PMID:18039974

  3. Delaying the onset of treadmill exercise following peripheral nerve injury has different effects on axon regeneration and motoneuron synaptic plasticity.

    PubMed

    Brandt, Jaclyn; Evans, Jonathan T; Mildenhall, Taylor; Mulligan, Amanda; Konieczny, Aimee; Rose, Samuel J; English, Arthur W

    2015-04-01

    Transection of a peripheral nerve results in withdrawal of synapses from motoneurons. Some of the withdrawn synapses are restored spontaneously, but those containing the vesicular glutamate transporter 1 (VGLUT1), and arising mainly from primary afferent neurons, are withdrawn permanently. If animals are exercised immediately after nerve injury, regeneration of the damaged axons is enhanced and no withdrawal of synapses from injured motoneurons can be detected. We investigated whether delaying the onset of exercise until after synapse withdrawal had occurred would yield similar results. In Lewis rats, the right sciatic nerve was cut and repaired. Reinnervation of the soleus muscle was monitored until a direct muscle (M) response was observed to stimulation of the tibial nerve. At that time, rats began 2 wk of daily treadmill exercise using an interval training protocol. Both M responses and electrically-evoked H reflexes were monitored weekly for an additional seven wk. Contacts made by structures containing VGLUT1 or glutamic acid decarboxylase (GAD67) with motoneurons were studied from confocal images of retrogradely labeled cells. Timing of full muscle reinnervation was similar in both delayed and immediately exercised rats. H reflex amplitude in delayed exercised rats was only half that found in immediately exercised animals. Unlike immediately exercised animals, motoneuron contacts containing VGLUT1 in delayed exercised rats were reduced significantly, relative to intact rats. The therapeutic window for application of exercise as a treatment to promote restoration of synaptic inputs onto motoneurons following peripheral nerve injury is different from that for promoting axon regeneration in the periphery. PMID:25632080

  4. Effects of hip and head position on ankle range of motion, ankle passive torque, and passive gastrocnemius tension.

    PubMed

    Andrade, R J; Lacourpaille, L; Freitas, S R; McNair, P J; Nordez, A

    2016-01-01

    Ankle joint range of motion (ROM) is notably influenced by the position of the hip joint. However, this result remains unexplained. Thus, the aim of this study was to test if the ankle passive torque and gastrocnemius muscle tension are affected by the hip and the head positions. The torque and the muscle shear elastic modulus (measured by elastography to estimate muscle tension) were collected in nine participants during passive ankle dorsiflexions performed in four conditions (by combining hip flexion at 90 or 150°, and head flexed or neutral). Ankle maximum dorsiflexion angle significantly decreased by flexing the hip from 150 to 90° (P < 0.001; mean difference 17.7 ± 2.5°), but no effect of the head position was observed (P > 0.05). Maximal passive torque and shear elastic modulus were higher with the hip flexed at 90° (P < 0.001). During submaximal ROM, no effects of the head and hip positioning (P > 0.05) were found for both torque and shear elastic modulus at a given common ankle angle among conditions. Shifts in maximal ankle angle due to hip angle manipulation are not related neither to changes in passive torque nor tension of the gastrocnemius. Further studies should be addressed to better understand the functional role of peripheral nerves and fasciae in the ankle ROM limits. PMID:25676048

  5. Treatment of Isolated Ankle Osteoarthritis with Arthrodesis or the Total Ankle Replacement: A Comparison of Early Outcomes

    PubMed Central

    Saltzman, Charles L.; Kadoko, Robert G.

    2010-01-01

    Background Ankle arthrodesis and replacement are two common surgical treatment options for end-stage ankle osteoarthritis. However, the relative value of these alternative procedures is not well defined. This study compared the clinical and radiographic outcomes as well as the early perioperative complications of the two procedures. Methods Between January 2, 1998 and May 31, 2002, 138 patients were treated with ankle fusion or replacements. Seventy one patients had isolated posttraumatic or primary ankle arthritis. However, patients with inflammatory arthritis, neuropathic arthritis, concomitant hind foot fusion, revision procedures and two component system ankle replacement were excluded. Among them, one group of 42 patients had a total ankle replacement (TAR), whereas the other group of 29 patients underwent ankle fusion. A complete follow-up could be performed on 89% (37/42) and 73% (23/29) of the TAR and ankle fusion group, respectively. The mean follow-up period was 4.2 years (range, 2.2 to 5.9 years). Results The outcomes of both groups were compared using a student's t-test. Only the short form heath survery mental component summary score and Ankle Osteoarthritis Scale pain scale showed significantly better outcomes in the TAR group (p < 0.05). In the radiographic evaluation, there was no significant difference in preoperative and postoperative osteoarthritis between the TAR and fusion groups. Conclusions The clinical results of TAR are similar to those of fusion at an average follow-up of 4 years. However, the arthroplasty group showed better pain relief and more postoperative complications that required surgery. PMID:20190994

  6. [Ankle fractures in the elderly patient].

    PubMed

    Crevoisier, Xavier; Baalbaki, Rayan; Dos Santos, Tiago; Assal, Mathieu

    2014-12-17

    Ankle fractures in adults are usually managed by open reduction internal fixation. In elderly patients the surgical dilemma relates to bone quality. Osteoporosis is the enemy of internal fixation, and secure purchase of screws in osteopenic bone may be difficult to achieve. Insufficient screw purchase may lead to loss of reduction, wound breakdown, and infection. Postoperative management after osteosynthesis usually requires an extended period of restricted weight bearing. However, this is not feasible in older patients as a result of their lack of strength in the upper extremities and frequent comorbidities. Therefore, augmen- ted methods of internal fixation and specific surgical techniques have been developed using metal and bone cement. This permits this fragile population to begin early full weight bearing in a removable brace. PMID:25752013

  7. Optimal management of ankle syndesmosis injuries

    PubMed Central

    Porter, David A; Jaggers, Ryan R; Barnes, Adam Fitzgerald; Rund, Angela M

    2014-01-01

    Syndesmosis injuries occur when there is a disruption of the distal attachment of the tibia and fibula. These injuries occur commonly (up to 18% of ankle sprains), and the incidence increases in the setting of athletic activity. Recognition of these injuries is key to preventing long-term morbidity. Diagnosis and treatment of these injuries requires a thorough understanding of the normal anatomy and the role it plays in the stability of the ankle. A complete history and physical examination is of paramount importance. Patients usually experience an external rotation mechanism of injury. Key physical exam features include detailed documentation about areas of focal tenderness (syndesmosis and deltoid) and provocative maneuvers such as the external rotation stress test. Imaging workup in all cases should consist of radiographs with the physiologic stress of weight bearing. If these images are inconclusive, then further imaging with external rotation stress testing or magnetic resonance imaging are warranted. Nonoperative treatment is appropriate for stable injuries. Unstable injuries should be treated operatively. This consists of stabilizing the syndesmosis with either trans-syndesmotic screw or tightrope fixation. In the setting of a concomitant Weber B or C fracture, the fibula is anatomically reduced and stabilized with a standard plate and screw construct. Proximal fibular fractures, as seen in the Maisonneuve fracture pattern, are not repaired operatively. Recent interest is moving toward repair of the deltoid ligament, which may provide increased stability, especially in rehabilitation protocols that involve early weight bearing. Rehabilitation is focused on allowing patients to return to their pre-injury activities as quickly and safely as possible. Protocols initially focus on controlling swelling and recovery from surgery. The protocols then progress to restoration of motion, early protected weight bearing, restoration of strength, and eventually a

  8. Ionic and pharmacological properties of reciprocal inhibition in Xenopus embryo motoneurones.

    PubMed Central

    Soffe, S R

    1987-01-01

    1. Properties of rhythmic, compound mid-cycle inhibitory post-synaptic potentials (i.p.s.p.s), which constitute one of the three main synaptic drives to motoneurones during fictive swimming in Xenopus embryos, have been examined using ionic and pharmacological manipulation. 2. Mid-cycle i.p.s.p.s are Cl- dependent. They are reversed by intracellular Cl- injection and attenuated by lowered extracellular Cl- concentration. 3. In response to bath application of 100 microM-glycine or 100 microM-gamma-aminobutyric acid (GABA), motoneurones show a decrease in cell input resistance of 24 +/- 2.9 M omega (mean +/- S.E. of mean) or 16 +/- 3.7% and 26 +/- 6.0 M omega or 14 +/- 2.0% respectively. This is associated with a weak hyperpolarization or depolarization of 0 +/- 1.5 mV and -3 +/- 1.4 mV respectively. Both responses can be made strongly depolarizing by intracellular Cl- injection. 4. The response to glycine is blocked by 1 microM-strychnine but is largely unaffected by bicuculline below 50 microM. The response to GABA is largely blocked by 10 microM-bicuculline but is unaffected by 1 microM-strychnine. Both strychnine and bicuculline are therefore specific antagonists in the amphibian embryo preparation. Glycine and GABA are both partially antagonized by 10 microM-picrotoxin. 5. Mid-cycle i.p.s.p.s recorded in motoneurones during fictive swimming are reduced in amplitude by 0.5-1 microM-strychnine but are largely unaffected by 40 microM-bicuculline. In embryos immobilized by ventral root transection, 100 microM-tubocurarine, a likely GABA antagonist in the embryo, has no effect on mid-cycle inhibition. Glycine is suggested to be the probable transmitter released by commissural interneurones and mediating mid-cycle inhibition during fictive swimming, acting to increase conductance of Cl-. PMID:3625556

  9. Properties of inward and outward potassium currents in cultured mouse motoneurons.

    PubMed

    McLarnon, J G; Kim, S U; Michikawa, M; Xu, R

    1995-01-01

    Inward rectifier potassium currents and calcium-dependent potassium currents have been studied in cultured embryonic mouse motoneurons. Sustained unitary inward rectifier potassium currents were recorded from cell-attached patches and the channel conductance was dependent on external K+ concentration with a value of 25 pS when external K+ was 140 mM. The channel open probability exhibited a sigmoidal dependence on potential with the largest values (near 0.7) at depolarizing patch potentials. Inactivating inward rectifier potassium currents were also recorded in some cell-attached patches following voltage steps to hyperpolarizing potentials with the rate of inactivation faster with larger hyperpolarizing steps. Whole-cell inward rectifier potassium currents increased from an initial level to a steady-state level with hyperpolarizing steps to -120 mV from a holding potential of -60 mV; with larger hyperpolarizing commands the peak currents decayed to the steady-state. The steady-state current-voltage relation exhibited a region of negative slope resistance. External Cs+ (0.5-1 mM) reduced the amplitudes of macroscopic currents and diminished the open times of unitary currents consistent with block of open rectifying channels with an estimated KD for channel block of 1 mM. A large conductance calcium-dependent potassium channel was isolated in inside-out patches with a conductance of 240 pS with symmetrical 140 mM K+ across the patches and a conductance of 110 pS when the external K+ was reduced to 5 mM. With symmetrical K+ the channel open probability exhibited a sigmoid dependence on potential with the largest values, in excess of 0.8, associated with patch depolarization. The dependence of open probability on potential was dependent on the concentrations of internal Ca2+ and external K+. Properties of inward rectifier and calcium-dependent K+ channels, such as the voltage dependence of open probability, are involved in the establishment of cellular excitability in

  10. Recent Advances in Foot and Ankle Surgery in Mainland China: Correction of Severe Foot and Ankle Deformities.

    PubMed

    Zhu, Yuan; Xu, Xiang-Yang; Wang, Bi-Bo

    2016-06-01

    Foot and ankle physicians in China encounter quite a large amount of severe and complex deformities. The main cause of severe ankle and foot deformity is trauma, while the other causes may be neuromuscular diseases, improper reduction and fixation and so on. Staged procedure may sometimes be a safer way to correct deformities in the presence of severe soft tissue contracture. Periarticular osteotomy combined with soft tissue balancing can be used in treating severe varus ankle arthritis, including stage IIIb cases and patients with talar tilt of more than 10 degrees. PMID:27261804

  11. Efficacy and Safety of Split Peroneal Tendon Lateral Ankle Stabilization.

    PubMed

    Shibuya, Naohiro; Bazán, D Issac; Evans, Andrew M; Agarwal, Monica R; Jupiter, Daniel C

    2016-01-01

    Chronic lateral ankle instability is a common condition. Split peroneal tendon lateral ankle stabilization, a modification of the Chrisman-Snook procedure, is biomechanically stable and often used for severe and/or recurrent chronic lateral ankle instability. The purpose of the present study was to evaluate the efficacy and safety of this technique. Specifically, the midterm recurrence of instability and postoperative complications, such as stiffness, neurologic pain, and wound healing complications, were evaluated. We evaluated 30 consecutive procedures with a minimal follow-up period of 1 year. The mean follow-up period was 25 ± 13 (median 19, range 13 to 62) months. Five patients (17%) developed recurrent ankle instability, of whom 4 underwent revision surgery. One superficial infection and two wound disruptions developed. Two patients experienced stiffness and eight (27%) surgically induced neurologic complaints, such as sural neuritis. Finally, 2 patients developed complex regional pain syndrome. PMID:26364699

  12. How to Strengthen Your Ankle After a Sprain

    MedlinePlus

    ... back to the starting position. Repeat 10 times. Tie the resistance bands around a fixed object and ... starting position and cycle your ankle 10 times. Tie the bands around an object to the outer ...

  13. Design of a portable hydraulic ankle-foot orthosis.

    PubMed

    Neubauer, Brett C; Nath, Jonathan; Durfee, William K

    2014-01-01

    Small-scale hydraulics is ideal for powered human assistive devices including powered ankle foot orthoses because a large torque can be generated with an actuator that is small and light. A portable hydraulic ankle foot orthosis has been designed and is undergoing preliminary prototyping and engineering bench test evaluation. The device provides 90 Nm of ankle torque and has an operating pressure of 138 bar (2,000 psi). The battery-operated hydraulic power supply weighs about 3 kg and is worn at the waist. The ankle component weighs about 1.2 Kg and connects to the power supply with two hoses. Performance simulation and preliminary bench testing suggests that the device could be useful in certain rehabilitation applications. PMID:25570175

  14. Argon beam coagulation in foot and ankle surgery.

    PubMed

    Adams, Melissa L; Steinberg, John S

    2011-01-01

    In this brief report, we introduce the principles, indications, advantages, disadvantages, and surgical techniques involved in the use of argon beam coagulation in foot and ankle surgery. PMID:21907597

  15. Ankle Injuries and Disorders - Multiple Languages: MedlinePlus

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Ankle Injuries and Disorders URL of this page: https://medlineplus.gov/languages/ankleinjuriesanddisorders.html Other topics A-Z A B ...

  16. Open and Arthroscopic Surgical Anatomy of the Ankle

    PubMed Central

    Frank, Rachel M.; Hsu, Andrew R.; Gross, Christopher E.; Walton, David M.

    2013-01-01

    Ankle-related complaints are among the most commonly encountered problems for musculoskeletal clinicians. Ankle pathology is widely variable, including, but not limited to, fractures, deformity, infection, oncologic diseases, neuromuscular conditions, and arthritis. While nonoperative management with activity modification, bracing and/or shoe modifications, and medications is usually indicated as first line of treatment, surgical intervention may become necessary. A thorough understanding of the complex anatomy and biomechanics of the ankle, and in particular, the potential neurovascular structures that may be encountered, is important to reduce complications and obtain good surgical outcomes. The purpose of this review is to discuss the most common open and arthroscopic exposures to the ankle with a focus on surgically relevant anatomy for each approach. PMID:24288614

  17. Clinical anatomy and biomechanics of the ankle in dance.

    PubMed

    Russell, Jeffrey A; McEwan, Islay M; Koutedakis, Yiannis; Wyon, Matthew A

    2008-01-01

    The ankle is an important joint to understand in the context of dance because it is the connection between the leg and the foot that establishes lower extremity stability. Its function coordinates with the leg and foot and, thus, it is crucial to the dancer's ability to perform. Furthermore, the ankle is one of the most commonly injured body regions in dance. An understanding of ankle anatomy and biomechanics is not only important for healthcare providers working with dancers, but for dance scientists, dance instructors, and dancers themselves. The bony architecture, the soft tissue restraints, and the locomotive structures all integrate to allow the athletic artistry of dance. Yet, there is still much research to be carried out in order to more completely understand the ankle of the dancer. PMID:19618582

  18. Management of Syndesmotic Ankle Injuries in Children and Adolescents.

    PubMed

    Shore, Benjamin J; Kramer, Dennis E

    2016-06-01

    Pediatric ankle injuries are common, especially in athletes; however, the incidence of syndesmosis injuries in children has been scarcely reported. Injuries to the ankle syndesmosis, termed "high ankle sprains," can affect high-level and recreational athletes and have been related to delayed return to play, persistent pain, and adult injuries have been associated with long-term disability. Syndesmotic injuries do occur in children, especially those who participate in sports that involve cutting and pivoting (football, soccer) or sports with rigid immobilization of the ankle (skiing, hockey). Unstable pediatric syndesmosis injuries requiring surgical fixation are often associated with concomitant fibular fracture in skeletally mature children. Physician vigilance and careful clinical examination coupled with appropriate radiographs can determine the extent of the injury in the majority of circumstances. PMID:27100034

  19. Ankle Injuries and Disorders - Multiple Languages: MedlinePlus

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Ankle Injuries and Disorders URL ... this page: https://www.nlm.nih.gov/medlineplus/languages/ankleinjuriesanddisorders.html Other topics A-Z A B ...

  20. Distraction-free ankle arthroscopy for anterolateral impingement.

    PubMed

    Rouvillain, Jean Louis; Daoud, Wael; Donica, Adrian; Garron, Emmanuel; Uzel, André Pierre

    2014-08-01

    The origin of chronic pain after external ankle sprain is better known with arthroscopy's contribution. Chronic hypertrophic synovitis of the anterolateral ankle region is seemingly the cause, resulting in "anterolateral ankle impingement." But is partial synovectomy with fibrosis resection under arthroscopy always possible without any distraction? Are results affected? This retrospective study concerned only patients with soft tissue ankle impingement. All cases with bone and joint diseases were excluded. The final sample of 24 patients had a mean age of 35 years (21-54 years) and presented anterolateral mechanical pain associated with oedema following external ankle sprain. Medical and rehabilitative treatment was undertaken for more than 6 months before arthroscopy. Average time between trauma and arthroscopy was 21 months (5-60 months). Clinical examination revealed no ankle instability or laxity. Debridement with joint lavage was systematically performed under arthroscopy without any distraction. Average patient follow-up was 22 months (12-92 months). All patients had a good Kitaoka score, with 22 patients registering excellent results. There were no septic complications or algodystrophy. Two transient hypoesthesias were observed in the dorsal surface and lateral border of the foot with full postoperative recovery at 6 months. Distraction was never used and simple dorsiflexion was sufficient to perform arthroscopic debridement. In this study, anterolateral ankle impingement diagnosis was primarily clinical. Arthroscopic treatment yielded significant benefits on pain, oedema and resumption of sport activities. Arthroscopic treatment of anterolateral ankle impingements is thus possible with simple dorsiflexion and no distraction, resulting in a possible decrease in complication rates. Level of evidence Retrospective cohort study, Level IV. PMID:24220747

  1. Supramalleolar Osteotomies for the Treatment of Ankle Arthritis.

    PubMed

    Hintermann, Beat; Knupp, Markus; Barg, Alexej

    2016-07-01

    Supramalleolar osteotomy is a joint-preserving surgical treatment for patients with asymmetric valgus or varus ankle arthritis. The primary goal of the procedure is to realign the spatial relationship between the talus and tibia and thereby normalize joint loading within the ankle. Procedures to balance the soft tissues, as well as hindfoot osteotomy and arthrodesis, may also be necessary. Clinical studies of supramalleolar osteotomy demonstrate that correction of the altered biomechanics associated with asymmetric arthritis improves functional outcomes. PMID:27195382

  2. Ultrasound-guided intervention in the ankle and foot.

    PubMed

    Drakonaki, Eleni E; Allen, Gina M; Watura, Roland

    2016-01-01

    In this comprehensive review, we discuss the main interventions performed in the foot and ankle for Achilles tendinopathy, Morton's neuromas and Plantar fasciitis as well as techniques for intra-articular and peritendinous injections. We present the different imaging techniques and injectable agents that can be used in clinical practice, trying to help the reader decide the most appropriate way of managing the patient with a problem in the ankle and foot. PMID:26537692

  3. Multivariable Dynamic Ankle Mechanical Impedance With Relaxed Muscles

    PubMed Central

    Lee, Hyunglae; Krebs, Hermano Igo; Hogan, Neville

    2015-01-01

    Neurological or biomechanical disorders may distort ankle mechanical impedance and thereby impair locomotor function. This paper presents a quantitative characterization of multivariable ankle mechanical impedance of young healthy subjects when their muscles were relaxed, to serve as a baseline to compare with pathophysiological ankle properties of biomechanically and/or neurologically impaired patients. Measurements using a highly backdrivable wearable ankle robot combined with multi-input multi-output stochastic system identification methods enabled reliable characterization of ankle mechanical impedance in two degrees-of-freedom (DOFs) simultaneously, the sagittal and frontal planes. The characterization included important ankle properties unavailable from single DOF studies: coupling between DOFs and anisotropy as a function of frequency. Ankle impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness in both seated (knee flexed) and standing (knee straightened) postures. Stiffness in the sagittal plane was greater than in the frontal plane and furthermore, was greater when standing than when seated, most likely due to the stretch of bi-articular muscles (medial and lateral gastrocnemius). Very low off-diagonal partial coherences implied negligible coupling between dorsiflexion-plantarflexion and inversion-eversion. The directions of principal axes were tilted slightly counterclockwise from the original joint coordinates. The directional variation (anisotropy) of ankle impedance in the 2-D space formed by rotations in the sagittal and frontal planes exhibited a characteristic “peanut” shape, weak in inversion-eversion over a wide range of frequencies from the stiffness dominated region up to the inertia dominated region. Implications for the assessment of neurological and biomechanical impairments are discussed. PMID:24686292

  4. Imaging of Common Arthroscopic Pathology of the Ankle.

    PubMed

    Grambart, Sean T

    2016-10-01

    Arthroscopy of the ankle is used in the treatment and diagnosis of a spectrum of intra-articular pathology including soft tissue and osseous impingement, osteochondral lesions, arthrofibrosis, and synovitis. To help identify the correct pathology, imaging techniques are often used to aid the surgeon in diagnosing pathology and determining best treatment options. This article discusses the use of imaging in various ankle pathologies. PMID:27599435

  5. Mechanics and energetics of incline walking with robotic ankle exoskeletons.

    PubMed

    Sawicki, Gregory S; Ferris, Daniel P

    2009-01-01

    We examined healthy human subjects wearing robotic ankle exoskeletons to study the metabolic cost of ankle muscle-tendon work during uphill walking. The exoskeletons were powered by artificial pneumatic muscles and controlled by the user's soleus electromyography. We hypothesized that as the demand for net positive external mechanical work increased with surface gradient, the positive work delivered by ankle exoskeletons would produce greater reductions in users' metabolic cost. Nine human subjects walked at 1.25 m s(-1) on gradients of 0%, 5%, 10% and 15%. We compared rates of O(2) consumption and CO(2) production, exoskeleton mechanics, joint kinematics, and surface electromyography between unpowered and powered exoskeleton conditions. On steeper inclines, ankle exoskeletons delivered more average positive mechanical power (P<0.0001; +0.37+/-0.03 W kg(-1) at 15% grade and +0.23+/-0.02 W kg(-1) at 0% grade) and reduced subjects' net metabolic power by more (P<0.0001; -0.98+/-0.12 W kg(-1) at 15% grade and -0.45+/-0.07 W kg(-1) at 0% grade). Soleus muscle activity was reduced by 16-25% when wearing powered exoskeletons on all surface gradients (P<0.0008). The ;apparent efficiency' of ankle muscle-tendon mechanical work decreased from 0.53 on level ground to 0.38 on 15% grade. This suggests a decreased contribution from previously stored Achilles' tendon elastic energy and an increased contribution from actively shortening ankle plantar flexor muscle fibers to ankle muscle-tendon positive work during walking on steep uphill inclines. Although exoskeletons delivered 61% more mechanical work at the ankle up a 15% grade compared with level walking, relative reductions in net metabolic power were similar across surface gradients (10-13%). These results suggest a shift in the relative distribution of mechanical power output to more proximal (knee and hip) joints during inclined walking. PMID:19088208

  6. Deep Vein Thrombosis in Foot and Ankle Surgery.

    PubMed

    Chao, John

    2016-04-01

    The routine use of venous thromboembolism prophylaxis in patients undergoing foot and ankle procedures is not well supported in the literature. Multiple studies draw conclusions from heterogeneous populations, and specific studies have small numbers of specific pathologic conditions. Depending on the study, recommendations for and against venous thromboembolism prophylaxis in foot and ankle surgery can be made. The identification of risk factors for venous thromboembolism is paramount in the decision making of postoperative venous thromboembolism prophylaxis. PMID:26772954

  7. The ANKLE TRIAL (ANKLE treatment after injuries of the ankle ligaments): what is the benefit of external support devices in the functional treatment of acute ankle sprain? : a randomised controlled trial

    PubMed Central

    2012-01-01

    Background Acute lateral ankle ligament injuries are very common problems in present health care. Still there is no hard evidence about which treatment strategy is superior. Current evidence supports the view that a functional treatment strategy is preferable, but insufficient data are present to prove the benefit of external support devices in these types of treatment. The hypothesis of our study is that external ankle support devices will not result in better outcome in the treatment of acute ankle sprains, compared to a purely functional treatment strategy. Overall objective is to compare the results of three different strategies of functional treatment for acute ankle sprain, especially to determine the advantages of external support devices in addition to functional treatment strategy, based on balance and coordination exercises. Methods/design This study is designed as a randomised controlled multi-centre trial with one-year follow-up. Adult and healthy patients (N = 180) with acute, single sided and first inversion trauma of the lateral ankle ligaments will be included. They will all follow the same schedule of balancing exercises and will be divided into 3 treatment groups, 1. pressure bandage and tape, 2. pressure bandage and brace and 3. no external support. Primary outcome measure is the Karlsson scoring scale; secondary outcomes are FAOS (subscales), number of recurrent ankle injuries, Visual Analogue Scales of pain and satisfaction and adverse events. They will be measured after one week, 6 weeks, 6 months and 1 year. Discussion The ANKLE TRIAL is a randomized controlled trial in which a purely functional treated control group, without any external support is investigated. Results of this study could lead to other opinions about usefulness of external support devices in the treatment of acute ankle sprain. Trial registration Netherlands Trial Register (NTR): NTR2151 PMID:22340371

  8. Cell size and geometry of spinal cord motoneurons in the adult cat following the intramuscular injection of adriamycin: comparison with data from aged cats.

    PubMed

    Liu, R H; Yamuy, J; Engelhardt, J K; Xi, M C; Morales, F R; Chase, M H

    1996-10-28

    Adriamycin (ADM), an antineoplastic antibiotic, when injected intramuscularly, is taken up by motoneuron axonal terminals and retrogradely transported to the motoneuron soma where it exerts its neurotoxic effect. In the present study, ADM was injected into the hindlimb muscles of five adult cats. Measurements of the electrophysiological properties of the lumbar motoneurons innervating these muscles were obtained using intracellular techniques. Based upon these data the equivalent cylinder model of motoneurons was employed to evaluate ADM-induced changes in cell size and cell geometry. The size of cell somas in the ventral horn was also measured using light microscopy and computer imaging software. There were significant increases in the membrane time constant (25%) and input resistance (50%) in motoneurons whose muscles were treated with ADM (ADM-MNs) compared with data from control motoneurons (control-MNs). The increase in membrane time constant is attributed to an increase in membrane resistance; the increase in input resistance appears to depend upon both an increase in membrane resistance and a decrease in total cell surface area. Cell capacitance, which is proportional to the total cell surface area, was significantly reduced (15%) in ADM-MNs. Calculations based on cable theory indicate that while there was no significant change in the length of the equivalent cylinder for ADM-MNs, there was a significant decrease (17%) in the diameter of the equivalent cylinder. These data indicate that there is a decrease in total cell surface area which can be attributed to the shrinkage of branches throughout the dendritic tree. There was also a small (7%) but statistically significant decrease in the electrotonic length of ADM-MNs. Morphological analysis also revealed that the mean cross-sectional area of the somas of those ventral horn neurons which are likely to correspond to the motoneuron population was significantly reduced on the ADM-treated side compared to that

  9. Motoneuron Intrinsic Properties, but Not Their Receptive Fields, Recover in Chronic Spinal Injury

    PubMed Central

    Kajtaz, Elma; Cain, Charlette M.; Heckman, C.J.

    2013-01-01

    Proper movement execution relies on precise input processing by spinal motoneurons (MNs). Spinal MNs are activated by limb joint rotations. Typically, their movement-related receptive fields (MRRFs) are sharply focused and joint-specific. After acute spinal transection MRRFs become wide, but their manifestation is not apparent, as intrinsic excitability, primarily resulting from the loss of persistent inward currents (PICs), dramatically decreases. PICs undergo a remarkable recovery with time after injury. Here we investigate whether MRRFs undergo a recovery that parallels that of the PIC. Using the chronic spinal cat in acute terminal decerebrate preparations, we found that MRRFs remain expanded 1 month after spinal transaction, whereas PICs recovered to >80% of their preinjury amplitudes. These recovered PICs substantially amplified the expanded inputs underlying the MRRFs. As a result, we show that single joint rotations lead to the activation of muscles across the entire limb. These results provide a potential mechanism for the propagation of spasms throughout the limb. PMID:24285887

  10. Descending pathways to the cutaneus trunci muscle motoneuronal cell group in the cat

    NASA Technical Reports Server (NTRS)

    Holstege, Gert; Blok, Bertil F.

    1989-01-01

    Pathways involved in the cutaneous trunci muscle (CTM) reflex in the cat were investigated. Experimental animals were injected with tritium-labeled L-leucine into their spinal cord, brain stem, or diencephalon and, after six weeks, perfused with 10-percent formalin. The brains and spinal cords were postfixed in formalin and were cut into transverse 25-micron-thick frozen sections for autoradiography. Results based on injections in the C1, C2, C6, and C8 segments suggest that propriospinal pathways to the CTM motor nucleus originating in the cervical cord do no exist, although these propriospinal projections are very strong to all other motoneuronal cell groups surrounding the CTM motor nucleus. The results also demonstrate presence of specific supraspinal projections to the CTM motor nucleus, originating in the contralateral nucleus retroambiguous and the ipsilateral dorsolateral pontine tegmentum.

  11. A Caged Ret Kinase Inhibitor and its Effect on Motoneuron Development in Zebrafish Embryos

    PubMed Central

    Bliman, David; Nilsson, Jesper R.; Kettunen, Petronella; Andréasson, Joakim; Grøtli, Morten

    2015-01-01

    Proto-oncogene tyrosine-protein kinase receptor RET is implicated in the development and maintenance of neurons of the central and peripheral nervous systems. Attaching activity-compromising photocleavable groups (caging) to inhibitors could allow for external spatiotemporally controlled inhibition using light, potentially providing novel information on how these kinase receptors are involved in cellular processes. Here, caged RET inhibitors were obtained from 3-substituted pyrazolopyrimidine-based compounds by attaching photolabile groups to the exocyclic amino function. The most promising compound displayed excellent inhibitory effect in cell-free, as well as live-cell assays upon decaging. Furthermore, inhibition could be efficiently activated with light in vivo in zebrafish embryos and was shown to effect motoneuron development. PMID:26300345

  12. A surgical ankle sprain pain model in the rat: Effects of morphine and indomethacin

    PubMed Central

    Young Kim, Hee; Wang, Jigong; Chung, Kyungsoon; Mo Chung, Jin

    2008-01-01

    Ankle sprain is a frequent injury in humans that results in pain, swelling and difficulty in walking on the affected ankle. Currently a suitable animal model resembling human ankle sprain is lacking. Here, we describe an animal ankle sprain model induced by ankle ligament injury (ALI) in rats. Cutting combinations of the lateral ankle ligament complex produced pain, edema and difficulty of weight bearing, thereby mimicking severe (grade III) ankle sprain in humans. Analgesic compounds, morphine and indomethacin, significantly reversed the reduced weight bearing, thus indicating that reduction of weight bearing is partially due to pain. The ALI model is a new ankle sprain model that may be useful for the study of ankle sprain pain mechanisms and treatments and for the screening of new analgesic drugs. PMID:18620022

  13. Conservative management of posterior ankle impingement: a case report

    PubMed Central

    Senécal, Isabelle; Richer, Nadia

    2016-01-01

    Objective: To describe the pain and functional improvements of a patient with posterior ankle impingement following a treatment plan incorporating soft tissue therapy, chiropractic adjustment and a progressive rehabilitation program. Clinical Features: A 37-year- old male presented with posterolateral ankle pain exacerbated by plantar flexion two weeks after sustaining an inversion ankle sprain. Oedema was present and the patient was describing a sensation of instability while walking. The initial diagnosis of lateral ankle sprain was found to be complicated by a posterior ankle impingement caused by a tenosynovitis of the flexor hallucis longus sheath suspected during the physical examination and confirmed by MRI. Intervention and Outcome: The patient was treated over a 14-week period. Soft tissue therapy, a rehabilitation program and cortisone injection were used to treat this condition. A precise description of the rehabilitation program that contains open kinetic chain, closed kinetic chain, proprioception, and conditioning exercises prescribed to the patient is given. After the treatment plan, the patient returned to play pain free and had no daily living restrictions. Summary: A protocol including rest, soft tissue therapy, open and closed kinetic chain exercises, sport-specific exercises and cortisone injection appeared to facilitate complete recovery of this patient’s posterior ankle impingement. PMID:27385836

  14. Biomechanical and Neuromuscular Effects of Ankle Taping and Bracing

    PubMed Central

    Wilkerson, Gary B.

    2002-01-01

    Objective: An extensive review of clinically relevant research is provided to assist clinicians in understanding the underlying mechanisms by which various ankle-support systems may provide beneficial effects. Strategies for management of different types of ankle ligament conditions are also discussed. Background: Much of the literature pertaining to ankle instability and external support has focused on assessment of inward displacement of the hindfoot within the frontal plane. Some researchers have emphasized the importance of (1) pathologic rotary displacement of the talus within the transverse plane, (2) the frequent presence of subtalar joint ligament lesions, and (3) the interrelated effects of ankle support on deceleration of inversion velocity and facilitation of neuromuscular response. Description: The traditional method for application of adhesive tape to the ankle primarily restricts inward displacement of the hindfoot within the frontal plane. The biomechanical rationale for a method of ankle taping that restricts lower leg rotation and triplanar displacement of the foot associated with subtalar motion is presented. Clinical Advantages: The lateral subtalar-sling taping procedure may limit strain on the anterior talofibular ligament associated with subtalar inversion, restrain anterolateral rotary subluxation of the talus in the presence of ligament laxity, and protect the subtalar ligaments from excessive loading. The medial subtalar sling may reduce strain on the anterior-inferior tibiofibular syndesmosis and enhance hindfoot-to-forefoot force transfer during the push-off phase of the gait cycle. PMID:12937565

  15. A novel assessment technique for measuring ankle orientation and stiffness.

    PubMed

    Zhang, Mingming; Davies, T Claire; Nandakumar, Anoop; Quan Xie, Sheng

    2015-09-18

    The measurement of ankle orientation and stiffness can provide insight into improvements and allows for effective monitoring during a rehabilitation program. Existing assessment techniques have a variety of limitations. Dynamometer based methods rely on manual manipulation. The use of torque meter is usually for single degree-of-freedom (DOF) devices. This study proposes a novel ankle assessment technique that can be used for multiple DOFs devices working in both manual and automatic modes using the position sensor and the multi-axis load cell. As a preliminary evaluation, an assessment device for ankle dorsiflexion and plantarflexion was constructed. Nine subjects participated to evaluate the effectiveness of the assessment device in determining ankle orientation and stiffness. The measured ankle orientation was consistent with that from the NDI Polaris optical tracking system. The measured ankle torque and stiffness compared well with published data. The test-retest reliability was high with intraclass correlation coefficient (ICC2, 1) values greater than 0.846 and standard error of measurement (SEM) less than 1.38. PMID:26159061

  16. Putative Excitatory and Putative Inhibitory Inputs Localize to Different Dendritic Domains in a Drosophila Flight Motoneuron

    PubMed Central

    Kuehn, Claudia; Duch, Carsten

    2012-01-01

    Input-output computations of individual neurons may be affected by the three-dimensional structure of their dendrites and by the targeting of input synapses to specific parts of their dendrites. However, only few examples exist where dendritic architecture can be related to behaviorally relevant computations of a neuron. By combining genetic, immunohistochemical, and confocal laser scanning methods this study estimates the location of the spike initiating zone and the dendritic distribution patterns of putative synaptic inputs on an individually identified Drosophila flight motorneuron, MN5. MN5 is a monopolar neuron with more than 4000 dendritic branches. The site of spike initiation was estimated by mapping sodium channel immunolabel onto geometric reconstructions of MN5. Maps of putative excitatory cholinergic and of putative inhibitory GABAergic inputs on MN5 dendrites were created by charting tagged Dα7 nicotinic acetylcholine receptors and Rdl GABAA receptors onto MN5 dendritic surface reconstructions. Although these methods provided only an estimate of putative input synapse distributions, the data indicated that inhibitory and excitatory synapses were targeted preferentially to different dendritic domains of MN5, and thus, computed mostly separately. Most putative inhibitory inputs were close to spike initiation, which was consistent with sharp inhibition, as predicted previously based on recordings of motoneuron firing patterns during flight. By contrast, highest densities of putative excitatory inputs at more distant dendritic regions were consistent with the prediction that in response to different power demands during flight, tonic excitatory drive to flight motoneuron dendrites must be smoothly translated into different tonic firing frequencies. PMID:23279094

  17. Mechanisms of disease: motoneuron disease aggravated by transgenic expression of a functionally modified AMPA receptor subunit.

    PubMed

    Kuner, Rohini; Groom, Anthony J; Müller, Gerald; Kornau, Hans-Christian; Stefovska, Vanya; Bresink, Iris; Hartmann, Bettina; Tschauner, Karsten; Waibel, Stefan; Ludolph, Albert C; Ikonomidou, Chrysanthy; Seeburg, Peter H; Turski, Lechoslaw

    2005-08-01

    To reveal whether increased Ca2+ permeability of glutamate AMPA channels triggered by the transgene for GluR-B(N) induces decline in motor functions and neurodegeneration in the spinal cord, we evaluated growth, motor coordination, and spinal reflexes in transgenic GluR-B(N) and wild-type (wt) mice. To reveal whether the transgenic GluR-B(N) expression aggravates the course of motoneuron disease in SOD1 mice, we mated heterozygous GluR-B(N) and SOD1 [C57BL6Ico-TgN(hSOD1-G93A)1Gur] mice to generate double-transgenic progeny. The phenotypic sequelae in mice carrying mutations were evaluated by monitoring growth, motor coordination, and survival. Neuronal degeneration was assessed by morphological and stereological analysis of spinal cord and brain. We found that transgenic expression in mice of GluR-B(N)-containing glutamate AMPA receptors with increased Ca2+ permeability leads to a late-onset degeneration of neurons in the spinal cord and decline of motor functions. Neuronal death progressed over the entire life span, but manifested clinically in late adulthood, resembling the course of a slow neurodegenerative disorder. Additional transgenic expression of mutated human SOD1 accelerated disease progression, aggravated severity of motor decline, and decreased survival. These observations reveal that moderate, but persistently elevated Ca2+ influx via glutamate AMPA channels causes degeneration of spinal motoneurons and motor decline over the span of life. These features resemble the course of sporadic amyotrophic lateral sclerosis (ALS) in humans and suggest that modified function of glutamate AMPA channels may be causally linked to pathogenesis of ALS. PMID:16179532

  18. F Wave Study in Amyotrophic Lateral Sclerosis: Assessment of Segmental Motoneuronal Dysfunction

    PubMed Central

    Fang, Jia; Cui, Li-Ying; Liu, Ming-Sheng; Guan, Yu-Zhou; Li, Xiao-Guang; Cui, Bo; Ding, Qing-Yun

    2015-01-01

    Background: Dysfunctional spinal circuit may play a role in the pathophysiology of amyotrophic lateral sclerosis (ALS). The purpose of this study was to use F waves for assessment of segmental motoneuronal excitability following upper motor neuron (UMN) dysfunctions in ALS. Methods: We studied the F waves of 152 ulnar nerves recorded from abductor digiti minimi in 82 patients with ALS. Two groups of hands were defined based on the presence or absence of pyramidal signs in the same upper limb. The group with pyramidal signs in the upper limbs was designated as the P group, and the group without pyramidal signs in the upper limbs was designated as the NP group. Results: The mean (P < 0.001), median (P < 0.001) and maximum (P = 0.035) F wave amplitudes, mean (P < 0.001), median (P < 0.001) and maximum (P = 0.003) F/M amplitude ratio, index repeating neuron (P < 0.001) and index repeater F waves (P < 0.001) of the P group were significantly increased compared with the NP group. No significant differences were identified for F wave chronodispersion (P = 0.628), mean F wave latency (P = 0.151), minimum F wave latency (P = 0.211), maximum F wave latency (P = 0.199), F wave persistence (P = 0.738), F wave duration (P = 0.152), F wave conduction velocity (P = 0.813) and number of giant F waves (P = 0.072) between the two groups. Conclusions: In this study, increased F wave amplitude, F/M amplitude ratio and number of repeater F waves reflected enhanced segmental motoneuronal excitability following UMN dysfunctions in ALS. PMID:26112713

  19. Electrophysiological and morphological measurements in cat gastrocnemius and soleus alpha-motoneurones.

    PubMed

    Ulfhake, B; Kellerth, J O

    1984-07-30

    Intracellular recording and staining with HRP was used to study the electrical properties and anatomical size of medial gastrocnemius (MG) and soleus (SOL) alpha-motoneurones in curarized cats. The MG motoneurones were divided into two groups on the basis of their input resistance (RN), namely low-resistance MG-LR cells (RN less than 1.0 M omega) and high-resistance MG-HR cells (RN greater than 1.0 M omega). Analysis of the voltage transients following applied current pulses indicated that the SOL neurones had longer membrane time constants (tau o) than the MG-LR cells, while the MG-HR group exhibited intermediate values. Using Rall's equivalent cylinder model, a difference in specific membrane resistivity (Rm) between the MG-LR (low Rm) and SOL (high Rm) cells was obtained. This difference was observed also in neurones of similar anatomical size, and was consistent with the observed difference in tau o. In two neurones Rm was in addition calculated directly from anatomy and input resistance according to the general solution for a continuous neurone model with arbitrary geometry given by Rall. The latter method was found to yield significantly lower values for Rm, although the observed difference between the neurone types remained similar. Also the values for electrotonic length (L) were found to differ considerably between the calculations based on voltage transient analysis and those obtained from combined physiological and anatomical measurements. The observed variations in results are discussed in relation to possible sources of error in the experimental techniques and/or in the theoretical assumptions, particularly that of Rm being uniform over the entire soma-dendritic membrane. It is suggested that Rm might be larger in the dendritic regions than in the soma. A crude approximation of the dendrite to soma conductance ratio (Q) indicated that most cells (80%) had Q greater than 5. PMID:6466992

  20. Early and selective loss of neuromuscular synapse subtypes with low sprouting competence in motoneuron diseases.

    PubMed

    Frey, D; Schneider, C; Xu, L; Borg, J; Spooren, W; Caroni, P

    2000-04-01

    The addition or loss of synapses in response to changes in activity, disease, or aging is a major aspect of nervous system plasticity in the adult. The mechanisms that affect the turnover and maintenance of synapses in the adult are poorly understood and are difficult to investigate in the brain. Here, we exploited a unique anatomical arrangement in the neuromuscular system to determine whether subtypes of synapses can differ in anatomical plasticity and vulnerability. In three genetic mouse models of motoneuron disease of diverse origin and severity, we observed a gradual and selective loss of synaptic connections that begun long before the onset of clinical deficits and correlated with the timing of disease progression. A subgroup of fast-type (fast-fatiguable) neuromuscular synapses was highly vulnerable and was lost very early on. In contrast, slow-type synapses resisted up to the terminal phase of the disease. Muscle-specific differences were also evident. Similar selective losses were detected in aged mice. These selective vulnerability properties of synapses coincided with hitherto unrecognized major differences in stimulus-induced anatomical plasticity that could also be revealed in healthy mice. Using paralysis and/or growth-associated protein 43 overexpression to induce synaptic sprouting, we found that slow-type, disease-resistant synapses were particularly plastic. In contrast, fast-type synapses with the highest vulnerability failed to exhibit any stimulus-induced change. The results reveal pronounced subtype specificity in the anatomical plasticity and susceptibility to loss of neuromuscular synapses and suggest that degenerative motoneuron diseases involve a common early pathway of selective and progressive synaptic weakening also associated with aging. PMID:10729333

  1. Location of motoneurones projecting to the cat distal forelimb. I. Deep radial motornuclei.

    PubMed

    Fritz, N; Illert, M; Saggau, P

    1986-02-15

    The position of the motornuclei projecting through the dorsal interosseus (DR) nerve to the distal forelimb muscles has been investigated in the cat. Horseradish peroxidase (HRP) and fluorescent (Fl) compounds have been used as retrograde tracers. They were either injected into forelimb muscles or applied to the proximal end of transected forelimb nerves. Limb muscles that were not investigated have been carefully denervated. HRP was used to trace the position and the architecture of the individual motornuclei. The topographical relations between the nuclei were established with application of up to three F compounds in the same animal. The position of the labeled motornuclei was reconstructed with a computer-assisted approach which is described in the appendix. The DR representation area extends from the caudal C5 to the caudal Th1 segments. In C6 it forms a dorsoventrally oriented narrow region at the lateral border of the ventral horn; in C7 and rostral C8 it forms a broad column in the dorsolateral corner of the ventral horn. In caudal C8 and Th1 this column is shifted into a ventral direction. The motoneurones projecting to the individual DR muscles are not randomly distributed in this area, but arranged in long, slender columns. These motornuclei occupy specific positions with only minimal interindividual variations. Three nuclei (brachioradialis, extensor carpi radialis, and supinator) are located in the C6 and C7 segments. They compose about one-third of the DR cell population. The nuclei to the other radial muscles are all located in C8 and Th1. Thus most of the DR motoneurones are located in these two segments. These results, together with those from the companion paper on the location of the median and ulnar motornuclei, provide important anatomical knowledge for the investigation of the cat brachial enlargement. PMID:3958228

  2. Differences in Dysfunction of Thenar and Hypothenar Motoneurons in Amyotrophic Lateral Sclerosis

    PubMed Central

    Fang, Jia; Cui, Liying; Liu, Mingsheng; Guan, Yuzhou; Li, Xiaoguang; Li, Dawei; Cui, Bo; Shen, Dongchao; Ding, Qingyun

    2016-01-01

    This study aimed to determine differences in spinal motoneuron dysfunction between the abductor pollicis brevis (APB) and the abductor digiti minimi (ADM) in amyotrophic lateral sclerosis (ALS) patients based on studying F-waves. Forty ALS patients and 20 normal controls (NCs) underwent motor nerve conduction studies on both median and ulnar nerves, including F-waves elicited by 100 electrical stimuli. The F-wave persistence (P < 0.05), index repeating neuron (RN; P < 0.001), and index repeater F-waves (Freps; P < 0.001) significantly differed between the APB and the ADM in the NC participants. For the hands of the ALS patients that lacked detectable wasting or weakness and exhibited either no or mild impairment of discrete finger movements, significantly reduced F-wave persistence (P < 0.001), increased index RN (P < 0.001), and increased index Freps (P < 0.001) were observed in APB in comparison with the normal participants, with relatively normal ADM F-wave parameters. For the hands of ALS patients that exhibited wasting and weakness, the mean F-wave amplitude (P < 0.05), the F/M amplitude ratio (P < 0.05), F-wave persistence (P < 0.001), index RN (P < 0.05), and index Freps (P < 0.05) significantly differed between APB and ADM. The differences in the dysfunction of motoneurons innervating APB and ADM are unique manifestations in ALS patients. The F-wave persistence (P = 0.002), index RN (P < 0.001), and index Freps (P < 0.001) in the APB seemed to differentiate ALS from the NCs more robustly than the ADM/APB Compound muscle action potential (CMAP) amplitude ratio. Thus, F-waves may reveal subclinical alterations in anterior horn cells, and may potentially help to distinguish ALS from mimic disorders. PMID:27014030

  3. Differences in Dysfunction of Thenar and Hypothenar Motoneurons in Amyotrophic Lateral Sclerosis.

    PubMed

    Fang, Jia; Cui, Liying; Liu, Mingsheng; Guan, Yuzhou; Li, Xiaoguang; Li, Dawei; Cui, Bo; Shen, Dongchao; Ding, Qingyun

    2016-01-01

    This study aimed to determine differences in spinal motoneuron dysfunction between the abductor pollicis brevis (APB) and the abductor digiti minimi (ADM) in amyotrophic lateral sclerosis (ALS) patients based on studying F-waves. Forty ALS patients and 20 normal controls (NCs) underwent motor nerve conduction studies on both median and ulnar nerves, including F-waves elicited by 100 electrical stimuli. The F-wave persistence (P < 0.05), index repeating neuron (RN; P < 0.001), and index repeater F-waves (Freps; P < 0.001) significantly differed between the APB and the ADM in the NC participants. For the hands of the ALS patients that lacked detectable wasting or weakness and exhibited either no or mild impairment of discrete finger movements, significantly reduced F-wave persistence (P < 0.001), increased index RN (P < 0.001), and increased index Freps (P < 0.001) were observed in APB in comparison with the normal participants, with relatively normal ADM F-wave parameters. For the hands of ALS patients that exhibited wasting and weakness, the mean F-wave amplitude (P < 0.05), the F/M amplitude ratio (P < 0.05), F-wave persistence (P < 0.001), index RN (P < 0.05), and index Freps (P < 0.05) significantly differed between APB and ADM. The differences in the dysfunction of motoneurons innervating APB and ADM are unique manifestations in ALS patients. The F-wave persistence (P = 0.002), index RN (P < 0.001), and index Freps (P < 0.001) in the APB seemed to differentiate ALS from the NCs more robustly than the ADM/APB Compound muscle action potential (CMAP) amplitude ratio. Thus, F-waves may reveal subclinical alterations in anterior horn cells, and may potentially help to distinguish ALS from mimic disorders. PMID:27014030

  4. Signaling mechanism underlying the histamine-modulated action of hypoglossal motoneurons.

    PubMed

    Liu, Zi-Long; Wu, Xu; Luo, Yan-Jia; Wang, Lu; Qu, Wei-Min; Li, Shan-Qun; Huang, Zhi-Li

    2016-04-01

    Histamine, an important modulator of the arousal states of the central nervous system, has been reported to contribute an excitatory drive at the hypoglossal motor nucleus to the genioglossus (GG) muscle, which is involved in the pathogenesis of obstructive sleep apnea. However, the effect of histamine on hypoglossal motoneurons (HMNs) and the underlying signaling mechanisms have remained elusive. Here, whole-cell patch-clamp recordings were conducted using neonatal rat brain sections, which showed that histamine excited HMNs with an inward current under voltage-clamp and a depolarization membrane potential under current-clamp via histamine H1 receptors (H1 Rs). The phospholipase C inhibitor U-73122 blocked H1 Rs-mediated excitatory effects, but protein kinase A inhibitor and protein kinase C inhibitor did not, indicating that the signal transduction cascades underlying the excitatory action of histamine on HMNs were H1 R/Gq/11 /phospholipase C/inositol-1,4,5-trisphosphate (IP3 ). The effects of histamine were also dependent on extracellular Na(+) and intracellular Ca(2+) , which took place via activation of Na(+) -Ca(2+) exchangers. These results identify the signaling molecules associated with the regulatory effect of histamine on HMNs. The findings of this study may provide new insights into therapeutic approaches in obstructive sleep apnea. We proposed the post-synaptic mechanisms underlying the modulation effect of histamine on hypoglossal motoneuron. Histamine activates the H1 Rs via PLC and IP3 , increases Ca(2+) releases from intracellular stores, promotes Na(+) influx and Ca(2+) efflux via the NCXs, and then produces an inward current and depolarizes the neurons. Histamine modulates the excitability of HMNs with other neuromodulators, such as noradrenaline, serotonin and orexin. We think that these findings should provide an important new direction for drug development for the treatment of obstructive sleep apnea. PMID:26811198

  5. Post-synaptic conductance increase associated with presynaptic inhibition in cat lumbar motoneurones.

    PubMed Central

    Carlen, P L; Werman, R; Yaari, Y

    1980-01-01

    1. Motoneurones were examined in which low-intensity p.b.s.t conditioning volleys caused a 5% or greater decrease of gastrocnemius monosynaptic e.p.s.p.s without evidence of long-lasting i.p.s.p.s on superimposed single sweeps. 2. Short constant current pulses were injected into these cells and in twenty-two of twenty-three cases the voltage decay was faster when preceded by the same p.b.s.t. conditioning stimuli which caused a decrease in the Ia e.p.s.p. 3. Comparing these decays to short pulse decays generated in a simple analogue neurone model suggested that after conditioning stimuli a tonic conductance increase had occurred which was located electrotonically remote from the soma in some cases or more diffusely in other cases. 4. Long-lasting i.p.s.p.s were brought out by averaging the baseline following conditioning stimuli in ten of fifteen cases, also suggesting a post-synaptic conductance increase. 5. Averaging the voltage response to long saturating constant current pulses showed a decreased motoneurone input resistance in three of eight cases. 6. The semilogarithmic decay of four of eleven conditioned e.p.s.p.s was more rapid than controls. 7. Although short pulse voltage decay analysis revealed consistent evidence for increased post-synaptic conductance following conditioning stimuli, it was not possible to decide if the location and extent of this conductance increase were sufficient to rule out presynaptic inhibition. PMID:7359439

  6. The modulation by 5-HT of glutamatergic inputs from the raphe pallidus to rat hypoglossal motoneurones, in vitro

    PubMed Central

    Bouryi, Vitali A; Lewis, David I

    2003-01-01

    Decreases in the activity of 5-HT-containing caudal raphe neurones during sleep are thought to be partially responsible for the resultant disfacilitation of hypoglossal motoneurones. Whilst 5-HT has a direct excitatory action on hypoglossal motoneurones as a result of activation of 5-HT2 receptors, microinjection of 5-HT2 antagonists into the hypoglossal nucleus reduces motor activity to a much lesser extent compared to the suppression observed during sleep suggesting other transmitters co-localised in caudal raphe neurones may also be involved. The aim of the present study was therefore to characterise raphe pallidus inputs to hypoglossal motoneurones. Whole cell recordings were made from hypoglossal motoneurones in vitro. 5-HT evoked a direct membrane depolarisation (8.45 ± 3.8 mV, P < 0.001) and increase in cell input resistance (53 ± 40 %, P < 0.001) which was blocked by the 5-HT2 antagonist, ritanserin (2.40 ± 2.7 vs. 7.04 ± 4.6 mV). Stimulation within the raphe pallidus evoked a monosynaptic EPSC that was significantly reduced by the AMPA/kainateantagonist, NBQX (22.8 ± 16 % of control, P < 0.001). In contrast, the 5-HT2 antagonist, ritanserin, had no effect on the amplitude of these EPSCs (106 ± 31 % of control, P = n.s.). 5-HT reduced these EPSCs to 50.0 ± 13 % of control (P < 0.001), as did the 5-HT1A agonist, 8-OH-DPAT (52.5 ± 17 %, P < 0.001) and the 5-HT1B agonist, CP 93129 (40.6 ± 29 %, P < 0.01). 8-OH-DPAT and CP 93129 increased the paired pulse ratio (1.38 ± 0.27 to 1.91 ± 0.54, P < 0.05 & 1.27 ± 0.08 to 1.44 ± 0.13, P < 0.01 respectively) but had no effect on the postsynaptic glutamate response (99 ± 4.4 % and 100 ± 2.5 %, P = n.s.). They also increased the frequency (P < 0.001), but not the amplitude, of miniature glutamatergic EPSCs in hypoglossal motoneurones. These data demonstrate that raphe pallidus inputs to hypoglossal motoneurones are predominantly glutamatergic in nature, with 5-HT decreasing the release of glutamate from

  7. Soma size and Cav1.3 channel expression in vulnerable and resistant motoneuron populations of the SOD1G93A mouse model of ALS

    PubMed Central

    Shoenfeld, Liza; Westenbroek, Ruth E.; Fisher, Erika; Quinlan, Katharina A.; Tysseling, Vicki M.; Powers, Randall K.; Heckman, Charles J.; Binder, Marc D.

    2014-01-01

    Abstract Although the loss of motoneurons is an undisputed feature of amyotrophic lateral sclerosis (ALS) in man and in its animal models (SOD1 mutant mice), how the disease affects the size and excitability of motoneurons prior to their degeneration is not well understood. This study was designed to test the hypothesis that motoneurons in mutant SOD1G93A mice exhibit an enlargement of soma size (i.e., cross‐sectional area) and an increase in Cav1.3 channel expression at postnatal day 30, well before the manifestation of physiological symptoms that typically occur at p90 (Chiu et al. 1995). We made measurements of spinal and hypoglossal motoneurons vulnerable to degeneration, as well as motoneurons in the oculomotor nucleus that are resistant to degeneration. Overall, we found that the somata of motoneurons in male SOD1G93A mutants were larger than those in wild‐type transgenic males. When females were included in the two groups, significance was lost. Expression levels of the Cav1.3 channels were not differentiated by genotype, sex, or any interaction of the two. These results raise the intriguing possibility of an interaction between male sex steroid hormones and the SOD1 mutation in the etiopathogenesis of ALS. PMID:25107988

  8. Neural circuits underlying tongue movements for the prey-catching behavior in frog: distribution of primary afferent terminals on motoneurons supplying the tongue.

    PubMed

    Kecskes, Szilvia; Matesz, Clara; Gaál, Botond; Birinyi, András

    2016-04-01

    The hypoglossal motor nucleus is one of the efferent components of the neural network underlying the tongue prehension behavior of Ranid frogs. Although the appropriate pattern of the motor activity is determined by motor pattern generators, sensory inputs can modify the ongoing motor execution. Combination of fluorescent tracers were applied to investigate whether there are direct contacts between the afferent fibers of the trigeminal, facial, vestibular, glossopharyngeal-vagal, hypoglossal, second cervical spinal nerves and the hypoglossal motoneurons. Using confocal laser scanning microscope, we detected different number of close contacts from various sensory fibers, which were distributed unequally between the motoneurons innervating the protractor, retractor and inner muscles of the tongue. Based on the highest number of contacts and their closest location to the perikaryon, the glossopharyngeal-vagal nerves can exert the strongest effect on hypoglossal motoneurons and in agreement with earlier physiological results, they influence the protraction of the tongue. The second largest number of close appositions was provided by the hypoglossal and second cervical spinal afferents and they were located mostly on the proximal and middle parts of the dendrites of retractor motoneurons. Due to their small number and distal location, the trigeminal and vestibular terminals seem to have minor effects on direct activation of the hypoglossal motoneurons. We concluded that direct contacts between primary afferent terminals and hypoglossal motoneurons provide one of the possible morphological substrates of very quick feedback and feedforward modulation of the motor program during various stages of prey-catching behavior. PMID:25575900

  9. Evaluating fracture risk in acute ankle sprains: Any news since the Ottawa Ankle Rules? A systematic review.

    PubMed

    Jonckheer, Pascale; Willems, Tine; De Ridder, Roel; Paulus, Dominique; Holdt Henningsen, Kirsten; San Miguel, Lorena; De Sutter, An; Roosen, Philip

    2016-03-01

    Background Ankle sprain is frequently encountered, both in primary care and in emergency departments. Since 1992, the Ottawa ankle rules (OAR) can assist clinicians in determining whether an X-ray should be performed to exclude a fracture. Several guidelines recommend the use of OAR based on a systematic review from 2003. Ten years later, one can wonder if this recommendation should be changed. Objective To review systematically the current evidence on the most accurate method to assess the fracture risk after an ankle sprain in adults. Methods A methodical search for systematic reviews, meta-analyses and primary studies was carried out in Medline, Cochrane Database of systematic reviews, Embase, Pedro, CINAHL, Medion and specific guideline search engines. At least two independent researchers performed selection, quality appraisal (with validated checklists) and data extraction. Results One systematic review and 21 primary studies were selected. Sensitivity and specificity of the OAR range from 92-100% and from 16-51%, respectively. To improve the OAR specificity, other tools are proposed such as the Bernese ankle rules. Vibrating tuning fork test and ultrasound could be useful in patient with OAR positive to decrease the need for radiographs. No evidence was found in favour of the use of magnetic resonance imaging (MRI) or computed tomography (CT) in the acute phase of ankle sprain. Conclusion The findings confirm the value of the OAR at ruling out fractures after an ankle sprain and propose other or additional tools to decrease the need for X-rays. PMID:26691309

  10. Quantitative analysis of human ankle characteristics at different gait phases and speeds for utilizing in ankle-foot prosthetic design

    PubMed Central

    2014-01-01

    Background Ankle characteristics vary in terms of gait phase and speed change. This study aimed to quantify the components of ankle characteristics, including quasi-stiffness and work in different gait phases and at various speeds. Methods The kinetic and kinematic data of 20 healthy participants were collected during normal gait at four speeds. Stance moment-angle curves were divided into three sub-phases including controlled plantarflexion, controlled dorsiflexion and powered plantarflexion. The slope of the moment-angle curves was quantified as quasi-stiffness. The area under the curves was defined as work. Results The lowest quasi-stiffness was observed in the controlled plantarflexion. The fitted line to moment-angle curves showed R2 > 0.8 at controlled dorsiflexion and powered plantarflexion. Quasi-stiffness was significantly different at different speeds (P = 0.00). In the controlled dorsiflexion, the ankle absorbed energy; by comparison, energy was generated in the powered plantarflexion. A negative work value was recorded at slower speeds and a positive value was observed at faster speeds. Ankle peak powers were increased with walking speed (P = 0.00). Conclusions Our findings suggested that the quasi-stiffness and work of the ankle joint can be regulated at different phases and speeds. These findings may be clinically applicable in the design and development of ankle prosthetic devices that can naturally replicate human walking at various gait speeds. PMID:24568175

  11. Iatrogenic posterior tibial nerve division during a combined anterior ankle arthroscopy with an additional posterolateral portal.

    PubMed

    Abdul-Jabar, Hani B; Bhamra, Jagmeet; Quick, Tom J; Fox, Michael

    2016-01-01

    Ankle arthroscopy is an important diagnostic and therapeutic technique in the management of ankle disorders. Nowadays ankle arthroscopy provides good to excellent results (up to 90%) in the treatment of certain intra-articular disorders. Due to the superficial location of ankle joint and the abundance of overlying neurovascular structures, complications reported in ankle arthroscopy are greater than those reported in other joints. We present the first reported case of a complete division of the posterior tibial nerve during an anterior ankle arthroscopy combin