It is known that free nerve endings are degenerated after application of shock waves. We therefore hypothesized that the application of shock waves to muscle induces dysfunction of neuromuscular transmission at neuromuscular junctions. We investigated changes in neuromuscular transmission in response to shock wave application. Sprague-Dawley rats were used in this study. Two thousand shock waves at an energy flux density of 0.18 mJ/mm 2 were applied to their right calf muscles. Neuromuscular junctions of gastrocnemius muscles were evaluated using rhodamine-a-bungarotoxin on the day of treatment (n ¼ 5). Amplitude and latency of compound muscle action potentials were measured on the day of treatment and 1, 2, 4, 6, and 8 weeks after treatment (n ¼ 10, each group). Degenerated acetylcholine receptors existed in all treated muscles. Although the action potential amplitude on the treated side was significantly less than on the control side from the day of treatment (25.1 AE 7.8 vs. 34.5 AE 9.1, p ¼ 0.012) to 6 weeks (27.9 AE 7.2 vs. 34.5 AE 7.2, p ¼ 0.037), there was no significant difference at 8 weeks. There was no significant difference in transmission latency between the groups. Keywords: neuromuscular junction; extracorporeal shock wave therapy; compound muscle action potential; neuromuscular transmission; acetylcholine receptor Impaired muscle coordination of limbs afflicted with central nervous system dysfunctions such as cerebral infarction, cerebral palsy, and dystonia is very common. This impairment causes severe limitations of daily living 1,2 and affects patients for their lifetime. Injection of botulinum toxin to focal muscles decreases muscle tone and is effective in improving motor function for impaired muscle coordination of limbs.3,4 For the past 20 years, treatment using botulinum toxin has gained acceptance as a popular treatment. However, the treatment using botulinum toxin has several difficulties with complications including severe allergic reaction and asthenia.3 Moreover, economic considerations inhibit many patients from undergoing this treatment because of its high cost. Recently, it has been reported that extra corporal shock wave treatment (ESWT) is able to improve function without inducing weakness in patients who suffer from spasticity and dystonia. 5,6 However, the mechanism of its clinical effect in the treatment of spasticity and dystonia has not been clarified. It is known that free nerve endings and sensory nerve fibers are degenerated after the application of shock waves.7,8 Therefore, we hypothesized that the application of shock waves to muscles induces dysfunction of neuromuscular transmission at neuromuscular junctions (NMJs). The purpose of this study was to investigate the changes in NMJs in response to ESWT to clarify its mechanism in the treatment of spasticity and dystonia. MATERIALS AND METHODSSeventy, 8-week-old male Sprague-Dawley rats (Japan SLC, Shizuoka, Japan) were used in this study. Animals were housed in an animal resources facility. Their room was mai...

This localized destruction of end plates may be caused by differences in acoustic impedance induced by the density of acetylcholine receptors. These results provide a possible mechanism for the effectiveness of rESW treatment for spasticity and dystonia. Muscle Nerve 57: 466-472, 2018.

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Pathomechanisms of injured-nerve pain have not been fully elucidated. Radicular pain and chronic constriction injury models have been established; however, producing these models is complicated. A sciatic nervepinch injury is easy to produce but the reliability of this model for evaluating pain behavior has not been examined. The current study evaluated pain-related behavior and change in pain markers in the dorsal root ganglion (DRG) of rats in a simple, sciatic nerve-pinch injury model. In the model, the sciatic nerve was pinched for 2 s using forceps (n = 20), but not injured in sham-operated animals (n = 20). Mechanical and thermal hyperalgesia were measured every second day for 2 weeks using von Frey filaments and a Hargreaves device. Calcitonin gene-related peptide (CGRP), activating transcription factor-3 (ATF-3), phosphorylated p38 mitogen activated protein (Map) kinase (p-p38), and nuclear factor-kappa B (NF-jB; p65) expression in L5 DRGs were examined at 4 and 7 days after surgery using immunohistochemistry. The proportion of neurons immunoreactive for these markers was compared between the two groups. Mechanical (during 8 days) and thermal hyperalgesia (during 6 days) were found in the pinch group rats, but not in the sham-operated animals (p \ 0.05); however, hyperalgesia was not significant from days 10 to 14. CGRP, ATF-3, p-p38, and NF-jB expression in L5 DRGs was upregulated in the nerveinjured rats compared with the sham-operated rats (p \ 0.01). Our results indicate that a simple sciatic nerve pinch produced pain-related behavior. Upregulation of the pain-marker expression in the nerve-injury model suggested it could be used as a model of pain. However, it was not considered as suitable for long-term studies.

Background The traditional curriculum for medical students in Japan does not include sufficient opportunities for students to develop their skills for musculoskeletal (MSK) examination and clinical reasoning and diagnosis. Therefore, an effective programme is required to help medical students and residents improve their clinical skills in MSK. This paper aims to assess the clinical skills of medical students who have participated in a peer role-playing simulation programme using a mini clinical evaluation exercise (mini-CEX). Methods Participants were 90 female medical students who were completing their first orthopaedic clinical clerkship. They were divided into two groups. The simulation group participated in a role-play focussed on MSK cases as low-fidelity simulation, a structured debriefing with the course supervisor, and a self-reflection on Day 1 (n = 64). The control group did not participate in the role-play due to randomised clerkship schedules (n = 26). On Day 2 of the intervention, we observed and assessed all participants’ performances during MSK outpatient encounters using the mini-CEX. We compared the mini-CEX score between the simulation group and the control group; the Wilcoxon rank-sum test was used for statistical analysis. Results The mini-CEX scores for physical examination, clinical reasoning and diagnosis, and overall clinical competency were significantly higher in the simulation group than in the control group (p < .05, physical examination: p = .014, clinical reasoning: p = .042, overall: p = .016). These findings suggest that medical students who partake in a peer role-playing simulation programme could experience improved clinical skills for physical examination, clinical reasoning and diagnosis, and overall clinical competency in real-life MSK outpatient encounters. Conclusions Through a mini-CEX assessment, our findings indicate that medical students who participated in our peer role-playing simulation programme have improved clinical skills. Peer role-playing as a low-fidelity simulation and practical educational opportunity will enable educators to polish the competency of medical students in musculoskeletal physical examinations and clinical reasoning and diagnosis in a clinical setting.

The aim of this study was to investigate the correlation of wrist extension strength (WES) and grip strength (GS) using a radial nerve block, and to determine the WES required to prevent the "wrist flexion phenomenon" (antagonistic WES) when making a fist. We tested 14 arms in seven healthy males. WES and GS were measured before blocking as standard WES and standard GS. All participants then had radial nerve blocks with mepivacaine hydrochloride. During the recovery process from radial nerve blockade, WES and GS were recorded every 5 minutes. There was a very strong correlation between WES and GS (p < 0.0001). The mean antagonistic WES was 51% of standard WES, and the mean GS, recorded at the same time, was 66% of standard GS.