Evaluation of hand-arm vibration syndrome owing to nerve conduction study and cumulative exposure index -A 2.5-year cohort study.

OBJECTIVE: This study aims to clarify the relationship between peripheral neuropathy in hand-arm vibration syndrome and cumulative exposure index. METHODS: 68 participants without symptoms were surveyed. The participants were divided into three groups based on past and current vibration exposure (VE). RESULTS: Comparison among groups according to past VE showed that the median and ulnar sensory nerve conduction velocities and median sensory nerve action potential (SNAP) amplitude were significantly lower in past high and low exposure groups than in the past non-exposure group. Comparison among groups according to current VE showed that the median and ulnar SNAP amplitudes were significantly lower in the current high exposure group than in the current low or non-exposure group. CONCLUSIONS: Vibration tool handlers have potential peripheral nerve lesions at a certain stage without subjective symptoms of the finger.

[A case of Charcot-Marie-Tooth disease type 2 caused by homozygous MME gene mutation].

The patient is a 44-year-old man. His parents are consanguineous. He experienced muscle weakness in his toe and distal tingling sensation in his feet at 42 years of age, which gradually progressed. Additionally, a marked cyanotic discoloration of the feet appeared and worsened progressively. Neurological examination revealed loss of tendon reflexes and distal muscle weakness in the lower extremities. Findings from nerve conduction studies indicated axonal polyneuropathy. Upon detection of the MME gene mutation, the patient was diagnosed with autosomal-recessive Charcot-Marie-Tooth disease 2T (ARCMT2T). In this case, cyanosis of the lower extremities possibly was associated with ARCMT2T, and it was suggested to be due to neprilysin deletion linked with the MME mutation. This represents the first documented occurrence of cyanosis as a distinctive feature of CMT with MME mutation.

Unclassified subtype of Guillain-Barré syndrome is associated with quick recovery.

Electrophysiological classification of Guillain-Barré syndrome (GBS) is important for predicting its clinical course; however, few reports discuss GBS patients who do not conform to the acute inflammatory demyelinating polyneuropathy (AIDP) or acute motor axonal neuropathy (AMAN) classifications. Therefore, the present study assessed the features of unclassified types of GBS and compared them to those of AIDP and AMAN. We compared clinical symptoms, nerve conduction, and laboratory data among patients with AIDP, AMAN, and unclassified subtypes of GBS, according to criteria developed by Rajabally, Hadden, and Ho. According to the Rajabally criteria, the F wave frequency in the upper and lower extremities was higher in the unclassified subgroup than in the AIDP and AMAN subgroups; however, according to the Hadden and Ho criteria, the F wave frequency in only the lower extremities was higher in the unclassified subgroup than in the other subgroups. The unclassified subgroup showed better prognosis using the Rajabally criteria. Classification with the Rajabally criteria is useful for predicting prognosis and determining treatment in patients with GBS. Moreover, unclassified patients exhibit the quickest recovery.

Late-onset Myasthenia Gravis Accompanied by Amyotrophic Lateral Sclerosis with Antibodies against the Acetylcholine Receptor and Low-density Lipoprotein Receptor-related Protein 4.

An 82-year-old woman developed neck weakness and dysarthria with antibodies against acetylcholine receptor (AChR) and low-density lipoprotein receptor-related protein 4 (LRP4). Myasthenia gravis (MG) was diagnosed by edrophonium and repetitive nerve stimulation tests. Her symptoms resolved completely by immunotherapy. One year later, she presented with muscle weakness and bulbar palsy accompanied by atrophy and fasciculation. Her tendon reflexes were brisk, and Babinski's sign was positive. She was diagnosed with probable amyotrophic lateral sclerosis (ALS). Immunotherapy did not improve her symptoms, and she ultimately died of respiratory failure. MG and ALS may share a pathophysiology, including anti-LRP4 antibodies at the neuromuscular junction.

Evoked potentials are useful for diagnosis of neuromyelitis optica spectrum disorder.

Neuromyelitis optica spectrum disorder (NMOSD) has been differentiated from relapsing-remitting multiple sclerosis (RRMS) by clinical, laboratory, and pathological findings, including the presence of the anti-aquaporin 4 antibody. Measurement of evoked potentials (EPs) is often used for the diagnosis of RRMS, although the possibility of applying EPs to the diagnosis of NMOSD has not been investigated in detail. Eighteen patients with NMOSD and 28 patients with RRMS were included in this study. The patients' neurological symptoms and signs were examined and their EPs were recorded. Characteristic findings were absence of visual evoked potentials and absence of motor evoked potentials in the lower extremities in patients with NMOSD, and a delay in these potentials in patients with RRMS. Most patients with NMOSD did not present abnormal subclinical EPs, whereas many patients with RRMS did. None of the patients with NMOSD showed abnormalities in auditory brainstem responses. NMOSD can be differentiated from RRMS by EP data obtained in the early stages of these diseases.

Effects of a polymorphism in the GFAP promoter on the age of onset and ambulatory disability in late-onset Alexander disease.

Alexander disease (AxD) is a rare neurodegenerative disorder. Most patients with AxD have a de novo dominant missense mutation in the glial fibrillary acidic protein (GFAP) gene. Patients with late-onset AxD exhibit a more variable onset and severity than patients with early-onset AxD, suggesting the existence of factors that modify the clinical phenotype of late-onset AxD. A -250-bp C/A single-nucleotide polymorphism (SNP) of the GFAP promoter (rs2070935) in the activator protein-1 binding site is a candidate factor for modification of the clinical phenotype. We analyzed the SNP in 10 patients with late-onset AxD and evaluated the effects of the SNP on the clinical course of late-onset AxD. Three of four cases with the C/C genotype lost the ability to walk in their 30s or 40s, whereas all six cases with the other genotypes retained the ability to walk throughout their 30s. The age of onset in patients with the C/C genotype was significantly earlier than in patients with the other genotypes (P<0.05). A more severe phenotype was observed in the patient in whom the C allele of rs2070935 was in cis with the GFAP mutation compared with the patient in whom the C allele of rs2070935 was in trans with the GFAP mutation. Our investigation revealed the possibility that the C/C genotype at rs2070935 of the GFAP promoter in late-onset AxD was associated with an earlier onset and a more rapid progression of ambulatory disability compared with the other genotypes.

Severe symptoms of 16q-ADCA coexisting with SCA8 repeat expansion.

We report a family with 16q-ADCA(16q 22.1 linked autosomal dominant cerebellar ataxia) coexisting with SCA8 repeat expansion. The brothers in this family presented with pyramidal signs, tremor, myoclonus and mental retardation in addition to cerebellar symptom in childhood. They showed both C-to-T substitution puratrophin-1 gene and an expanded allele of the SCA8 gene in the brothers and their father. These siblings presented with atypical symptoms and early onset age as16q-ADCA. Although it remains controversial whether the expanded SCA8 allele is associated with cerebellar symptoms, the coexistence of SCA8 repeat expansion with SCA6 was reported previously. Pure or predominant cerebellar symptoms were found in patients with SCA8, SCA6 and 16q-ADCA. In addition, common findings in neuropathology of SCA8, SCA6 and 16q-ADCA have been reported. We suppose that coexistence of SCA8 repeat expansion with 16q-ADCA may be involved in the pathogenesis and severe symptoms in this family.

[Occupation and carpal tunnel syndrome].

Carpal tunnel syndrome (CTS), compression of the median nerve at the carpal tunnel of the wrist, is the most common of all entrapment syndromes. Diabetes, Rheumatoid arthritis, hypothyroidism and pregnancy are known to cause CTS. And certain occupations were been reported the risk factor of CTS. We report two patients with occupationally induced CTS, and discuss the relation between the development of CTS and occupation with reference to previous papers. Occupations that appear to promote CTS were classified in to three groups: jobs entailing the use of vibratory tools, assembly work and food processing and packing. These occupations involved repeated flexion and extension of the wrist. The prevalence of CTS was related to not only repetitive work but also forceful work involving the wrist. Both occupational and non-occupational factors (gender, age, body mass index, thyroid function and diabetes mellitus) were considered risk factors for CTS. The prevalence of CTS in Visual Display Terminal (VDT) workers was not high compared to that in control groups. If the cause of CTS is considered to be due to an occupational factor, the patient would be eligible workmen's compensation, and should be suspended from work as soon as possible. It has been reported that assembly line workers showed resolution of symptoms and normal nerve conduction studies after 2 years of a reduced work schedule. Treatment for CTS should begin early. When these workers return to work, the environment and the condition of work should be improved to prevent recurrence.

Unilateral positive-negative myoclonus in Creutzfeldt-Jakob disease.

We report a patient with Creutzfeldt-Jakob disease who presented asymmetric myoclonus. Positive-negative myoclonus was seen only in the right extremities in association with periodic synchronous discharges (PSDs) on the electroencephalogram, although pure positive myoclonus was rarely seen in the left extremities, independently in PSDs. The duration of the silent period recorded in the right-hand muscle produced by transcranial magnetic stimulation was much longer than that in the left-hand muscle or that in normal subjects. Brain MRI diffusion-weighted images showed signal hyperintensities in the putamen and cerebral cortex, including the motor cortex, predominantly on the left side.

Ischemic ocular motor nerve palsy in three patients with end-stage renal disease.

Three patients on long-term hemodialysis therapy presented with sudden-onset isolated abducent nerve palsy. Two patients had ipsilateral eye pain. Computed tomographic scan or magnetic resonance imaging of the head did not reveal intracranial lesions responsible for the palsy. During the follow-up, the abducent nerve palsy of all three patients was resolved. Based on these findings, the three patients were diagnosed as having ischemic ocular motor nerve palsy. Although patients with end-stage renal disease often possess risk factors for ischemic ocular motor nerve palsy (hypertension, diabetes and atherosclerosis), the occurrence of ischemic ocular motor nerve palsy in the course of end-stage renal disease is rare.