Becker Muscular Dystrophy Accompanied by Anti-HMGCR Antibody-positive Immune-mediated Necrotizing Myopathy.

Becker muscular dystrophy (BMD) is an X-linked neuromuscular disease characterized by progressive muscle weakness that currently has no cure. Immune-mediated necrotizing myopathy (IMNM) is a type of autoimmune inflammatory myopathy characterized by proximal muscle weakness that is treated with immunosuppressive therapy. We herein report a patient diagnosed with BMD complicated with IMNM by a pathological analysis. Notably, the patient had an elevated serum anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody level. Oral glucocorticoid and methotrexate treatment partially improved the muscle weakness with decreased levels of serum creatine kinase. An accurate diagnosis is important for therapeutic decisions in these complicated cases.

A novel method to measure sensory nerve conduction of the posterior antebrachial cutaneous nerve.

INTRODUCTION/AIMS: Posterior antebrachial cutaneous (PABC) nerve conduction studies could be useful for distinguishing PABC neuropathy from C7 radiculopathy. In the conventional method using an antidromic method, the sensory nerve action potential (SNAP) is sometimes followed by a large volume-conducted motor potential. In this report we describe a reliable nerve conduction study using an orthodromic method for recording SNAPs of the PABC nerve. METHODS: Thirty-six healthy volunteers participated in this study. PABC SNAPs were recorded by placing a surface-active electrode 2 cm anterior to the lateral epicondyle. The PABC nerve was stimulated 10 cm distal to the active recording electrode along a line from the recording point to the mid-dorsum of the wrist, midway between the radial and ulnar styloid processes. We also performed PABC nerve conduction studies using an antidromic method and compared the findings. RESULTS: PABC SNAPs were recorded bilaterally from all subjects. The mean peak-to-peak amplitude for SNAPs was 13.4 ± 4.8 µV. Mean maximum conduction velocity was 62.7 ± 3.9 m/s and mean negative peak conduction velocity was 51.2 ± 2.6 m/s. The mean side-to-side difference in amplitude was 22.1 ± 16.0%. The mean amplitude of SNAPs obtained by our method was 48.9% higher than that of SNAPs obtained by the conventional method (13.4 vs 9.0 µV; P < .001). In contrast to the conventional method, our method enabled SNAPs to be recorded without a volume-conducted motor potential. DISCUSSION: The higher mean amplitude of SNAPs with our method enables them to be obtained easily.

Anatomical variations of the superficial branch of the radial nerve and the dorsal branch of the ulnar nerve: A detailed electrophysiological study.

INTRODUCTION: In this study we evaluated anatomic variations of the superficial branch of the radial nerve (SBRN) and the dorsal branch of the ulnar nerve (DBUN) electrophysiologically. METHODS: Antidromic nerve conduction studies (NCS) of the SBRN and DBUN were performed on healthy individuals. To identify individual responses from the distal branches of the SBRN and DBUN, sensory nerve action potentials of each finger (lateral side/medial side) were recorded. RESULTS: NCS were performed in 50 hands of 27 healthy control subjects. The thumb and the index finger were supplied by the SBRN in all cases. The lateral and medial sides of the third finger were supplied by the SBRN in 94.0% and 74.0% of the cases, but the lateral and medial sides of the fourth finger were supplied by the SBRN in only 10.0% and 2.0% of cases. The fifth finger and the medial side of the fourth finger were always supplied by the DBUN. The lateral side of the fourth finger was supplied by the DBUN in 98.0% of cases, but the lateral and medial sides of the third finger were supplied by the DBUN in 40.0% and 70.0% of cases. Dual innervation by the SBRN and DBUN was found in 34.0% and 46.0% of the lateral and medial sides of the third finger, but in only 8.0% and 2.0% of the lateral and medial sides of the fourth finger. DISCUSSION: There are considerable anatomic variations of the SBRN and DBUN in healthy individuals.

Relationship between the Diabetic Polyneuropathy Index and the Neurological Findings of Diabetic Polyneuropathy.

Objective To achieve an accurate quantification in diabetic polyneuropathy (DPN), we developed a new electrophysiological index that we called the DPN index. The relationship between the DPN index and the neurological findings in diabetic patients was assessed. Methods The DPN index was calculated by the mean value of percentages of four parameters (tibial compound muscle action potential amplitude / F wave minimum latency, sural sensory nerve action potential amplitude / sensory nerve conduction velocity) against the mean normal values. Twenty healthy subjects were recruited as a control group. Patients A total of 348 diabetic patients who were hospitalized in our hospital during the period from December 2016 to August 2019 were retrospectively studied. The correlations between the DPN index and five neurological findings (subjective sensory symptoms, diminished or absent Achilles tendon reflex, impaired tactile and vibration sense, low coefficient of variation of R-R interval) were evaluated. Results The DPN index in healthy subjects was 129.3±32.7%. The DPN index in diabetic patients with one or more neurological findings was significantly lower than that in diabetic patients without any neurological findings (p<0.01: 89.3±27.8% vs. 118.4±21.2%). For each of the five neurological findings, the DPN index in the group with an abnormality was significantly lower than that in the group without any abnormality (each p<0.01). Spearman's correlation coefficients indicated that a greater number of neurological findings resulted in a lower DPN index (r=-0.711, p<0.01). Conclusion Our study suggested that the DPN index is useful for evaluating the severity of DPN.

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

OBJECTIVE: We investigated how the active electrode placement site influences compound muscle action potential (CMAP) configuration of the upper trapezius muscle (TM). METHODS: A nerve conduction study of the accessory nerve was performed, and the CMAPs obtained with two different placement sites, i.e., placement of the active recording electrode on the belly of the upper TM (CMAP-A) and placement of the electrode 2 cm behind the belly (CMAP-B), were compared. CMAPs were also obtained with the active recording electrode placed in the supraspinous fossa (CMAP-C). RESULTS: All CMAPs were recorded from 21 healthy volunteers. The mean peak-to-peak amplitude of CMAP-B was 3.4 mV higher than that of CMAP-A (11.0 ±â€¯4.0 mV vs. 14.4 ±â€¯4.9 mV; P < 0.01). The mean peak-to-peak amplitude of CMAP-C was 10.3 ±â€¯5.0 mV. CONCLUSIONS: CMAP of the upper TM was always higher when the active recording electrode was placed 2 cm behind the belly of the muscle. SIGNIFICANCE: When stimulating the accessory nerve, a current spread occurs to the C5 spinal nerve root and another CMAP originating from the supraspinatus muscle occurs in the supraspinous fossa. The volume conduction from the supraspinatus muscle affects the active recording electrode on the TM, resulting in an increase in CMAP amplitude.

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.

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.

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.

[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.

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.

[Acute fulminant brachial plexopathy with good recovery: electrophysiological features].

We report a case of fulminant brachial plexopathy with radicular involvement. A 25-year-old man developed acute total monoplegia in the left upper limb. Needle electromyography showed extensive acute denervation in the C5-T1 spinal segments, and peripheral sensory nerve conduction was normal, mimicking a pre-ganglionic lesion. However, left median somatosensory evoked potentials revealed abnormal Erb's point potential, suggesting a brachial plexus lesion. Corticosteroid treatment resulted in good recovery. These findings suggest that the primary pathophysiology was conduction block and this can explain the good clinical recovery in this patient.

Coexistence of Creutzfeldt-Jakob disease, Lewy body disease, and Alzheimer's disease pathology: an autopsy case showing typical clinical features of Creutzfeldt-Jakob disease.

We report here an autopsy case of sporadic Creutzfeldt-Jakob disease (CJD) without hereditary burden and with a clinical course typical of sporadic CJD. A 77-year old man developed memory disturbance, followed by gait disturbance and myoclonus. He died of bronchopneumonia 5 months after the disease onset. Post-mortem examination revealed neuronal loss, astrocytosis, and patchy spongiosis in the cerebral cortex and lenticular nuclei. Synaptic-type deposits of prion protein were present in the cerebral cortex. Additionally, Lewy bodies were observed in the cerebral cortex and substantia nigra. Furthermore, senile plaques compatible with definite Alzheimer's disease according to Consortium to Establish a Registry for Alzheimer's disease criteria and neurofibrillary changes of the limbic system consistent with Braak stage IV were found. Based on a review of the published literature, this autopsy case is very rare, and we suppose that the incidence of CJD accompanied by Lewy body disease and Alzheimer's disease is very low.