BACKGROUND AND PURPOSE: X-linked bulbospinal muscular atrophy (X-BSMA) is characterized by bulbar and spinal muscular weakness and fasciculations. Although X-BSMA is a motor neuronopathy, there are several reports of myasthenic symptoms or decremental responses to repetitive nerve stimulation (RNS). We report the results of applying the RNS test to 15 patients among 41 with genetically confirmed X-BSMA; these 15 patients complained of fatigue, ease of becoming tired, or early muscular exhaustion. METHODS: The 3-Hz RNS test was performed on the trapezius, nasalis, orbicularis oculi, flexor carpi ulnaris, and abductor digiti quinti muscles. A decrement greater than 10% was considered abnormal. Additionally, a pharmacologic response to neostigmine was identified in three patients. RESULTS: A significant decrement was observed in 67% of patients, and was most common in the trapezius muscle (nine cases). The decrement of the trapezius muscle response ranged from 15.9% to 36.9%. The decrement was inversely correlated with the amplitude of compound muscle action potentials at rest. Neostigmine injection markedly improved the decrement in three patients, who showed noticeable decremental responses to 3-Hz RNS. CONCLUSIONS: This study shows that myasthenic symptoms and abnormal decremental responses to low-rate RNS are common in X-BSMA.
Action Potentials ; Bulbo-Spinal Atrophy, X-Linked ; Fasciculation ; Fatigue ; Humans ; Motor Neuron Disease ; Muscle Weakness ; Muscles ; Muscular Atrophy ; Myasthenia Gravis ; Neostigmine ; Neuromuscular Junction

BACKGROUND AND PURPOSE: Charcot-Marie-Tooth disease (CMT) type 1A (CMT1A) is the demyelinating form of CMT that is significantly associated with PMP22 duplication. Some studies have found that the disease-related disabilities of these patients are correlated with their compound muscle action potentials (CMAPs), while others have suggested that they are related to the nerve conduction velocities. In the present study, we investigated the correlations between the disease-related disabilities and the electrophysiological values in a large cohort of Korean CMT1A patients. METHODS: We analyzed 167 CMT1A patients of Korean origin with PMP22 duplication using clinical and electrophysiological assessments, including the CMT neuropathy score and the functional disability scale. RESULTS: Clinical motor disabilities were significantly correlated with the CMAPs but not the motor nerve conduction velocities (MNCVs). Moreover, the observed sensory impairments matched the corresponding reductions in the sensory nerve action potentials (SNAPs) but not with slowing of the sensory nerve conduction velocities (SNCVs). In addition, CMAPs were strongly correlated with the disease duration but not with the age at onset. The terminal latency index did not differ between CMT1A patients and healthy controls. CONCLUSIONS: In CMT1A patients, disease-related disabilities such as muscle wasting and sensory impairment were strongly correlated with CMAPs and SNAPs but not with the MNCVs or SNCVs. Therefore, we suggest that the clinical disabilities of CMT patients are determined by the extent of axonal dysfunction.
Action Potentials ; Axons ; Charcot-Marie-Tooth Disease ; Cohort Studies ; Humans ; Muscles ; Neural Conduction

The publisher wishes to apologize for incorrectly displaying the author (Seok Beom Gwon) name. We correct his name from Seok Beom Gwon to Seok Beom Kwon.

BACKGROUND AND PURPOSE: Amyotrophic lateral sclerosis (ALS) patients display easy fatigability and abnormal decrements on repetitive nerve stimulation (RNS) test of clinically involved limb muscles, which can result in ALS being misdiagnosed as myasthenia gravis. We retrospectively analyzed the RNS tests of ten ALS patients with only or predominant oropharyngeal symptoms without ocular or facial weakness. METHODS: RNS tests were performed on the abductor digiti quinti, flexor carpi ulnaris, orbicularis oculi (OO), nasalis and trapezius muscles at low-rate stimulation frequencies of 3 and 5-Hz. Decrements greater than 10% of the compound muscle action potential amplitude on the fifth stimulation compared to the first was regarded as abnormal. RESULTS: Six patients complained of muscular fatigue or diurnal fluctuation. Among the ten patients, three exhibited abnormal decrements during low-rate stimulation in the facial muscles but not in the limb muscles, two exhibited abnormal decrements in the OO and nasalis muscles, and one exhibited abnormal decrements in the OO muscle. CONCLUSIONS: These findings show that the facial muscles may be involved in some early oropharyngeal forms of ALS, although facial weakness may not be clinically evident. We confirm herein that abnormal decrement of facial muscles to RNS test cannot make a definite diagnose for myasthenia gravis.
Action Potentials ; Amyotrophic Lateral Sclerosis ; Extremities ; Facial Muscles ; Humans ; Muscle Fatigue ; Muscles ; Myasthenia Gravis ; Retrospective Studies

OBJECTIVE: To ascertain the etiology of non-traumatic plexopathy and clarify the clinical, electrophysiological characteristics according to its etiology. METHOD: We performed a retrospective analysis of 63 non-traumatic plexopathy patients that had been diagnosed by nerve conduction studies (NCS) and needle electromyography (EMG). Clinical, electrophysiological, imaging findings were obtained from medical records. RESULTS: We identified 36 cases with brachial plexopathy (BP) and 27 cases with lumbosacral plexopathy (LSP). The causes of plexopathy were neoplastic (36.1%), thoracic outlet syndrome (TOS) (25.0%), radiation induced (16.7%), neuralgic amyotrophy (8.3%), perioperative (5.6%), unknown (8.3%) in BP, while neoplastic (59.3%), radiation induced (22.2%), neuralgic amyotrophy (7.4%), psoas muscle abscess (3.7%), and unknown (7.4%) in LSP. In neoplastic plexopathy, pain presented as the first symptom in most patients (82.8%), with the lower trunk of the brachial plexus predominantly involved. In radiation induced plexopathy (RIP), pain was a common initial symptom, but the proportion was smaller (50%), and predominant involvements of bilateral lumbosacral plexus and whole trunk of brachial or lumbosacral plexus were characteristic. Myokymic discharges were noted in 41.7% patients with RIP. Abnormal NCS finding in the medial antebrachial cutaneous nerve was the most sensitive to diagnose TOS. Neuralgic amyotrophy of the brachial plexus showed upper trunk involvement in all cases. CONCLUSION: By integrating anatomic, pathophysiologic knowledge with detailed clinical assessment and the results of ancillary studies, physicians can make an accurate diagnosis and prognosis.
Abscess ; Adult ; Brachial Plexus ; Brachial Plexus Neuritis ; Brachial Plexus Neuropathies ; Electromyography ; Electrophysiology ; Humans ; Lumbosacral Plexus ; Needles ; Neural Conduction ; Prognosis ; Psoas Muscles ; Retrospective Studies ; Thoracic Outlet Syndrome

We report a 55-year-old man with chronic weakness of both legs with recently experienced nasal voice. Despite the absence of sensory symptoms, electrophysiologic studies revealed the presence of sensorimotor polyneuropathy. A sural-nerve biopsy showed remarkable reduction of large myelinated fibers with prominent remyelination. Intravenous immunoglobulin was administered due to suspected chronic demyelinating neuropathy, but had no effect. Abnormal trinucleotide-repeat expansion of the androgen receptor gene was subsequently detected in both the patient and his family. These observation indicate that prominent remyelinating features are not necessarily indicative of demyelinating neuropathy.
Biopsy ; Bulbo-Spinal Atrophy, X-Linked ; Humans ; Immunoglobulins ; Leg ; Middle Aged ; Myelin Sheath ; Organic Chemicals ; Polyneuropathies ; Receptors, Androgen ; Sural Nerve ; Voice

BACKGROUND: Facioscapulohumeral muscular dystrophy (FSHD) is associated with contractions of the polymorphic D4Z4-repeat array in 4q35 and has the distinctive clinical presentation of an initial involvement of the facial, shoulder-girdle, and upper-arm muscles. The aim of the present study was to determine clinical characteristics in Korean patients with FSHD and potential relationships between contracted D4Z4-repeat size and the FSHD phenotype. METHODS: We studied 34 genetically confirmed patients who had repeat sizes less than 38 kb, and analyzed their clinical manifestations with a structured protocol. The expressed phenotypes were scored according to the Clinical Severity Score formulated by Ricci and van Overveld. RESULTS: The clinical spectrum ranged widely, from asymptomatic individuals with minimal signs to wheelchair- bound patients. The initial affects were mainly in the facial muscles (68.8%), followed by the shoulder-girdle muscle (28.1%). Asymmetric features of the face and shoulder girdle were also important findings (71.9% and 90.0%, respectively). Winging scapular (87.5%), transverse smile (84.4%), Beevor's sign (68.8%), and sleeping with eyes opened (59.4%) were clinically important signs. There was a significant negative correlation between repeat size and clinical severity (r=-0.38, p=0.03). CONCLUSIONS: Distinctive clinical characteristics of FSHD are descending progression and asymmetric distribution of the muscle weakness. Our results also confirmed that the severity of FSHD increases with decreasing D4Z4-repeat size.
Contracts ; Eye ; Facial Muscles ; Genotype ; Humans ; Muscle Weakness ; Muscles ; Muscular Dystrophies ; Muscular Dystrophy, Facioscapulohumeral ; Phenotype ; Shoulder

BACKGROUND: Mutations in mitofusin2 (MFN2) are a major underlying cause of axonal Charcot-Marie-Tooth neuropathy (CMT). It has been reported that patients with an early age of onset (<10 years, EO) show more severe clinical phenotypes than those of patients with a later age at onset (> or =10 years, LO) in CMT2A with MFN2 mutations. There are few studies about CMT patients with MRI studies and we performed leg MRIs for better understanding of CMT2A. METHODS: We identified 19 patients (EO=10; LO=9) with MFN2 mutations. We used functional disability scales and CMT neuropathy scales for the grading of disability. Nerve conduction studies and MRIs of the lower leg were performed in all patients. RESULTS: We confirmed that EO had more severe leg muscle involvement than LO by leg MRI. In 7 out of 9 in LO, there were some degree of asymmetric leg muscle weakness and MRI findings explained the nature of asymmetry, that is, asymmetric cross-sectional areas or fatty infiltration. MRI of EO showed marked fatty infiltration on all three compartments whereas that of LO showed rather selective involvement of the posterior compartment. These results were well correlated with clinical findings that in LO, five patients could not do toe walking whereas only one could not do heel walking. CONCLUSIONS: MRI of the leg may be a useful tool for evaluating axonal CMT neuropathy, and asymmetric leg muscle weakness may be the characteristics of an axonal CMT. In addition, more prominent involvement of the posterior leg in LO is a very interesting phenomenon, which is in contrast to the length-dependent involvement in congenital demyelinating neuropathy.
Age of Onset ; Axons* ; Charcot-Marie-Tooth Disease ; Heel ; Humans ; Leg* ; Magnetic Resonance Imaging* ; Muscle Weakness ; Neural Conduction ; Phenotype ; Toes ; Walking ; Weights and Measures

BACKGROUND: Mitofusin 2 (MFN2) is a membrane protein and is an essential component of mitochondrial fusion machinery. Mitochondrial fusion is essential for various biological functions in mammalian cells. Thus mutations in MFN2 are the underlying cause of Charcot-Marie-Tooth neuropathy type 2A (CMT2A). However, there has been no reports investigating the MFN2 genes in Korean CMT patients. Therefore, we investigated to find the clinical and genetic characteristics in Korean patients with the MFN2 gene mutation. METHODS: We examined the mutations of the MFN2 gene in 137 Korean CMT families. According to criteria from the European CMT consortium, CMT2 was 45 families. Mutations were confirmed by both strands sequencing. Nerve conduction studies were carried out in CMT patients having each mutation. RESULTS: Eight pathogenic mutations were found in 10 families. Six mutations (Leu92Pro, Gly127Asp, His165Arg, Ser263Pro, Arg364Trp, Met376Thr) were determined to be novel, and those were not detected in the 100 healthy controls. A de novo missense mutation was found in three CMT families (30%). The frequency of the MFN2 mutation was 22.2%, which was higher than those found in the Cx32 mutation. In CMT2A, the frequencies with early age at onset (<10 years) and flat feet were 46.2%. CONCLUSIONS: We found MFN2 mutations in patients with sporadic or dominantly inherited CMT. In the majority of cases with CMT type 2, the axonal neuropathy, may be due to MFN2 mutations.
Axons ; Charcot-Marie-Tooth Disease ; Flatfoot ; Humans ; Membrane Proteins ; Mitochondrial Dynamics ; Mutation, Missense ; Neural Conduction

Mitochondrial DNA (mtDNA) deletions have been found in a majority of patients with Kearns-Sayre syndrome (KSS). The proband, a 14-year-old male, presented with retinitis pigmentosa, bilateral ptosis with an external opthalmoplegia, and ragged-red fibers in his biceps. The common 5-kb deleted mtDNA was identified in the patient by a long template PCR and DNA sequencing analysis. The deletion was located within the 8469-1344 position and a 13-kb direct repeat sequence was shown in the junction.
Adolescent ; DNA, Mitochondrial* ; Humans ; Kearns-Sayre Syndrome* ; Male ; Mitochondria ; Polymerase Chain Reaction ; Repetitive Sequences, Nucleic Acid ; Retinitis Pigmentosa ; Sequence Analysis, DNA