Taiji Nagai

Variations in the distal branches of the superficial fibular sensory nerve

Introduction: We evaluated anatomic variations of distal branches of the superficial fibular sensory nerve electrophysiologically. Methods: Orthodromic nerve conduction studies (NCS) of the first and third branches (M‐I, M‐III) of the medial dorsal cutaneous nerve and the fourth and fifth branches (I‐IV, I‐V) of the intermediate dorsal cutaneous nerve (IDCN) were performed. To find anomalous innervations from the dorsal sural nerve (DSN) in the IDCN territory, NCS of the fourth and fifth branches (S‐IV, S‐V) of the DSN were also performed. Results: All sensory nerve action potentials (SNAPs) of M‐I and M‐III could be obtained bilaterally from 31 healthy Japanese volunteers. SNAPs of I‐IV and I‐V were recordable in 85.5% and 43.5% of feet, respectively. Anomalous innervations from the DSN were confirmed in 71.0% of S‐IV and 93.5% of S‐V. Conclusion: These results suggest that anatomical variations in the IDCN territory are very frequent in Japanese subjects. Muscle Nerve 55: 74–76, 2017

A NOVEL METHOD TO MEASURE SENSORY NERVE CONDUCTION OF THE SUPRACLAVICULAR NERVE

Introduction: In this report we describe a reliable method for recording sensory nerve action potentials (SNAPs) of the supraclavicular nerve. Methods: Supraclavicular SNAPs were recorded by placing a surface active electrode at the posterior border of the sternocleidomastoid muscle at a distance of 6 cm from the sternoclavicular joint. The nerve was stimulated at the lower border of the clavicle 4.5 cm lateral to the sternoclavicular joint. Results: Supraclavicular SNAPs were recorded bilaterally from 20 healthy volunteers. Mean onset latency was 1.0 ± 0.2 ms, and mean peak latency was 1.4 ± 0.3 ms. Mean baseline‐to‐peak amplitude for the SNAPs was 6.1 ± 2.2 µV, and mean maximum conduction velocity was 59.8 ± 6.2 m/s. The mean percentage of side‐to‐side difference in amplitude was 12.9 ± 11.0%. Conclusions: Supraclavicular SNAPs could be obtained in all normal subjects. Assessment of supraclavicular nerve conduction is very useful in the diagnosis of supraclavicular neuropathy Muscle Nerve 50: 1005–1007, 2014

Whole plantar nerve conduction study with disposable strip electrodes.

Introduction: A new method to evaluate whole plantar nerve conduction with disposable strip electrodes (DSEs) is described. Methods: Whole plantar compound nerve action potentials (CNAPs) were recorded at the ankle. DSEs were attached to the sole for simultaneous stimulation of medial and lateral plantar nerves. We also conducted medial plantar nerve conduction studies using an established method and compared the findings. Results: Whole plantar CNAPs were recorded bilaterally from 32 healthy volunteers. Mean baseline to peak amplitude for CNAPs was 26.9 ± 11.8 μV, and mean maximum conduction velocity was 65.8 ± 8.3 m/s. The mean amplitude of CNAPs obtained by our method was 58.2% higher than that of CNAPs obtained by the Saeed method (26.9 μV vs. 17.0 μV; P < 0.0001). Conclusions: The higher mean amplitude of whole plantar CNAPs obtained by our method suggests that it enables CNAPs to be obtained easily, even in elderly people. Muscle Nerve 53: 209–213, 2016

Guillain–Barré syndrome after trivalent influenza vaccination during pregnancy

We present a case of a 30-year-old pregnant woman (para 1) with Guillain–Barré syndrome occurring at 36 weeks and 2 days of gestation, 24 days after receiving a trivalent influenza vaccine [A/California/7/2009(X-179A)(H1N1)pdm09; A/Texas/50/2012(X223)(H3N2); B/Massachusetts/2/2012(BX-51B)] during the 2013– 2014 season. On admission (6 days after onset), her pregnancy course was uneventful, and the fetal status was unremarkable. A neurological examination revealed the absence of deep tendon reflexes for all extremities, left side dominant facial weakness, paraesthesia in the distal part of all extremities, and incomplete urinary retention. On the Medical Research Council (MRC) scale, muscle strength in the proximal limbs was graded 4/5. A nerve conduction study performed at admission revealed absent F waves in the median, ulnar, and tibial nerve. Sensory nerve conduction studies showed low amplitude potential in the median nerve, and normal sural response. A diagnosis of Guillain–Barré syndrome with acute inflammatory demyelinating polyneuropathy (AIDP) was strongly suggested; this was consistent with the results of the second nerve conduction study performed 4 weeks later. A laboratory test conducted on admission did not show any evidence of bacterial or viral infection, and antiganglioside antibodies were not detected. On the day after admission (7 days after onset), we started a 5 day course of high-dose intravenous immunoglobulin (IVIG) at 22.5 g/day. On day 10 after onset, the patient lost the ability to walk by herself. On days 11 through 16, the symptoms did not show any further exacerbation, and a gradual recovery occurred thereafter. On day 24 after onset (39 weeks and 4 days of gestation), spontaneous labour occurred and the patient vaginally delivered a female baby weighing 3161 g. The course of delivery was smooth and uneventful, except for a short episode of orthostatic hypotension that occurred immediately after the delivery. The uterus contracted sufficiently after delivery, and the total blood loss was 570 g. The baby’s APGAR scores were 8 and 9 at 1 and 5 min after delivery, respectively. On serial neurological examinations, the baby did not show any signs of muscle weakness. The patient’s symptoms continued to improve after delivery and on day 32 after onset, the patient regained the ability to walk by herself. On day 54 after onset, she was discharged from hospital with near full recovery from the symptoms. Respiratory failure did not occur during the course of the disease. A causal relationship between Guillain–Barré syndrome and the influenza vaccine has been recognized since swine influenza vaccines containing A/NJ/76(H1N1) were administered to about 45 million people in 1976 [1]. During a 20-year period, from 1990– 2009, two cases of Guillain–Barré syndrome in pregnant women

Influence of placement sites of the active recording electrode on CMAP configuration in the trapezius muscle

Highlights • The active recording electrode site influences the CMAP waveform of the trapezius muscle (TM).• CMAP becomes high by placement of the active recording electrode 2 cm behind the belly of the TM.• Volume conduction from the supraspinatus muscle affects the CMAP waveform of the TM.

Clinical and pathological findings in familial amyloid polyneuropathy caused by a transthyretin E61K mutation

Familial amyloid polyneuropathy (FAP) is an autosomal dominant hereditary systemic amyloidosis caused by mutation of the transthyretin (TTR) gene, and usually shows sensory-dominant polyneuropathy and autonomic neuropathy at the initial stage. The pathogenesis of this neuropathy remains unknown, although several mechanisms, including mechanical compression, vessel occlusion, TTR toxicity and Schwann cell dysfunction have been proposed. We describe a patient with late-onset FAP caused by a TTR E61K mutation. Amyloid deposits were not detected in the endoneurium or perineurium of the sural nerve 7years after the onset of the disease, but a marked loss of nerve fibers was observed in the sural nerve. TTR-derived amyloid deposits were confirmed in the peroneus brevis muscle, salivary gland and heart tissue. DNA analysis revealed a heterozygous mutation in TTR. These findings suggest that proximal parts of the peripheral nervous system might be strongly affected by TTR aggregates or amyloid fibrils, and that the blood-nerve barrier in distal parts of peripheral nerves are initially preserved in this patient. This case indicates that several biopsy sites other than nerves may be helpful and necessary for the diagnosis of TTR amyloidosis in mild or late-onset FAP.

A new technique for dorsal sural nerve conduction study with surface strip electrodes

OBJECTIVE To obtain higher amplitude of dorsal sural sensory nerve action potentials (SNAPs), we used a new method for dorsal sural nerve conduction study with surface strip electrodes (SSEs). METHODS Dorsal sural SNAPs were recorded orthodromically. The recording electrodes were placed behind the lateral malleolus. SSEs were attached to the laterodorsal aspect of the foot for stimulation of the dorsal sural nerve (DSN). We also used a conventional method with a standard bipolar stimulator and compared the findings. RESULTS Dorsal sural SNAPs were recordable bilaterally from 49 healthy volunteers. Mean peak-to-peak amplitude for SNAPs was 12.9±6.3μV, and mean nerve conduction velocity was 44.8±5.5m/s. The mean amplitude of SNAPs obtained by our method was 118.6% higher than that of SNAPs obtained by the conventional method (12.9μVvs. 5.9μV; P<0.001). CONCLUSIONS The highest amplitude of dorsal sural SNAPs was constantly obtained by SSEs since SNAPs arising from whole digital branches of the DSN could be elicited by placement of SSEs. SIGNIFICANCE When the DSN supplies more cutaneous branches to the lateral half of the foot, SSEs gives higher amplitude of dorsal sural SNAPs than that of the standard innervation type.

[Sporadic Late-Onset Nemaline Myopathy Associated with MGUS].

Sporadic late-onset nemaline myopathy is an uncommon disease. Clinically, it is characterized by progressive muscle weakness that can develop in limbs or axial muscles. Asymmetrical distal weakness, facial weakness, dropped head, and dysphagia can also occur. Since the serum creatine kinase level usually remains within the normal range, patients can be misdiagnosed with motor neuron disease. Recognition of nemaline rods on muscle biopsy is crucial for accurate diagnosis. If it is associated with monoclonal gammopathy of undetermined significance, the outcome is known to be unfavorable. In spite of various immunotherapies such as corticosteroids, immunosuppressants, and plasmapheresis, most patients die of respiratory failure within 5 years. Since the efficacy of autologous stem cell transplantation following high-dose melphalan was first reported in 2008, there have been accumulating reports that showed the positive effect of this therapy for the disease.

Focal myopathy in the neck extensor muscles in Japanese Parkinson's disease patients with dropped head syndrome

The underlying etiology of dropped head syndrome (DHS) in Parkinsons disease (PD) patients seems to be heterogeneous, that is neck dystonia, a drug‐induced etiology or focal myopathy of the neck extensor muscles. Focal myopathy might be primary myositis or a stretched muscle injury. In Japan, several reports have argued that neck dystonia is the cause of DHS. There have been no reports to date that documented a focal myopathy of the neck extensor muscles. The aim of the present study was to investigate myopathic changes in the neck extensor muscles of PD patients with DHS by needle electromyography (EMG), and to evaluate the effect of steroid therapy.

69. Followup needle electromyography findings in parkinson’s disease patients with dropped head syndrome after steroid therapy

generative disorder involving the basal ganglia and it is thought to spare the peripheral nervous system. However, ambiguous sensory symptoms including pain and numbness are recognized non-motor manifestations that affect between 40% and 75% of IPD patients. Objectives: The association of peripheral neuropathy and sensory symptoms of IPD were investigated through electrophysiological tests. Methods: Twenty-five patients with IPD associated with ambiguous sensory symptoms were recruited. The Hoehn and Yahr scale was used to evaluate disease severity in the IPD patients and electrophysiological tests of the ulnar, median, peroneal, posterior tibial, and sural nerves were performed. The association between sensory symptoms and the levodopa daily dose was analyzed. The patients were also categorized into two groups according to their Hoehn and Yahr stage and analyzed the correlation between the severity of IPD and peripheral nerve disorder. Results: Only 10 patents showed normal findings on nerve conduction tests. In these studies, there were significant abnormal findings of sensory conduction of the ulnar and sural nerves and terminal latency of the peroneal and posterior tibial motor nerves. Abnormal findings of sensory nerves significantly correlated with a high dose of levodopa and long disease duration. But there was no significant difference of eletrophysological tests between disease severity. Conclusion: It was shown that IPD patients with sensory symptoms might have electrophysiological abnormalities regardless of disease severity. The authors suggest that IPD is neurodegenerative disease involving the peripheral nerve system exhibiting as non-motor symptoms.