Biomedical subjects
Publications and source records attributed to S J Oh.
Vasculitic neuropathy classically manifests as a subacute mononeuritis multiplex or polyneuropathy. Patients with a Guillain-Barré syndrome (GBS)-like presentation are usually not considered to have an underlying vasculitis. We describe 2 patients with rapidly progressive areflexic paralysis that was initially diagnosed as GBS, in whom vasculitic neuropathy was found histologically.
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The diagnostic sensitivity of three laboratory tests [serum antiacetylcholine receptor antibody (AChR-ab) assay, the repetitive nerve stimulation (RNS) test, and, the single fiber EMG (SFEMG)] for myasthenia gravis (MG) was compared in 120 patients. In all cases, at least one of the tests was abnormal. SFEMG was the most sensitive test, being abnormal in 92% of cases, followed by the RNS test (77%) and the AChR-ab assay (73%). SFEMG was abnormal in all cases with negative AChR-ab and RNS tests, in 97% of cases with negative AChR-ab assay, in 89% of cases with negative RNS test, and in 89% of cases with mild MG. We conclude that one of these three tests is abnormal in all cases of MG, and that the SFEMG is most sensitive in the diagnosis of MG.
The clinical electrophysiological and histological features of 10 cases of "chronic sensory demyelinating neuropathy" (CSDN) are reported. This entity is characterised by: 1) subacute or chronic progression; 2) pure sensory neuropathy; 3) high spinal fluid protein in the majority of cases; 4) electrophysiological evidence of demyelination affecting motor as well as sensory nerve fibres; 5) demyelination on sural nerve biopsy and 6) good response to immunotherapy in progressive phase. It is believed that this entity represents chronic inflammatory demyelinating polyneuropathy (CIDP) presenting as pure sensory neuropathy.
The existence of chronic "limb-girdle" form of myasthenia gravis (MG) has been questioned. We report here 12 such patients (10 women and two men) who constituted 3.8% of 314 MG patients in our study. The duration of disease ranged from 4 months to 7 years before the diagnosis. In almost all cases, the initial diagnosis was other than MG. None of the patients had any oculobulbar weakness. Acetylcholine receptor antibody was positive in five cases, although not all in the first assay. Repetitive nerve stimulation test was positive in all cases, although not necessarily the first time. Single-fiber EMG was positive in 11 cases. All patients responded to acetylcholinesterase inhibitors, and two thirds underwent immunotherapy. Diagnosis of limb-girdle MG requires a strong index of suspicion.
Myoclonic epilepsy with ragged-red fibers (MERRF) has been associated with an A--G transition at mtDNA nt 8344, within a conserved region of the tRNA(Lys) gene. Although the 8344 mutation is highly prevalent in patients with MERRF, it is not observed in 10%-20% of the cases, suggesting genetic heterogeneity. We have sequenced the tRNA(Lys) gene of five MERRF patients lacking the common 8344 mutation. One of these showed a novel T-->C transition at nucleotide position 8356, disrupting a highly conserved base pair in the T psi C stem. The mutant mtDNA population was essentially homoplasmic in muscle but was heteroplasmic in blood (47%). Neither 20 patients with other mitochondrial diseases nor 25 controls carried this mutation. These findings suggest that tRNA(Lys) alterations may play a specific role in the pathogenesis of MERRF syndrome.
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Paraneoplastic vasculitic neuropathy has been recently described. We report the first case of this disorder which responded both clinically and electrophysiologically to cyclophosphamide treatment. A 54-year-old woman with a history of metastatic endometrial carcinoma in remission had asymmetrical polyneuropathy, electrophysiological findings consistent with a diffuse axonal neuropathy, high sedimentation rate and spinal fluid protein, and microvasculitis with axonal degeneration on nerve biopsy. The patient was treated with 150 mg of cyclophosphamide daily with gradual clinical and electrophysiological improvement.
Plantar nerve conduction studies 14 months to 3.5 years after decompression surgery in 3 cases of tarsal tunnel syndrome showed an improvement in motor conduction as well as in sensory nerve conduction. This electrophysiological improvement was associated with clinical improvement. However, minor abnormalities still existed in sensory nerve conduction in all 3 cases.
The specific binding of HeLa cell factors to DNA sequences at the Epstein-Barr virus (EBV) latent origin of DNA replication was detected by gel shift experiments and DNase I footprinting analysis. These cellular proteins protected at least five discrete regions of the DNA replication origin. The viral protein required for EBV plasmid replication, EBV nuclear antigen 1 (EBNA-1), binds to specific sequences within the origin region. The HeLa cell proteins competed with EBNA-1 for binding to EBV origin DNA in vitro, leading to the possibility that these cellular proteins regulate EBV DNA replication by displacing EBNA-1 at the origin sites.
Comprehensive electrophysiological studies were performed on 13 patients with arsenic neuropathy. The most prominent finding was a marked abnormality in sensory nerve conduction in the presence of moderate abnormalities in motor nerve conduction. The motor nerve conduction studies and needle EMG were typical of those seen in axonal degeneration which was confirmed by sural nerve biopsy.
Creutzfeldt-Jakob disease (CJD) is presumably caused by a slow infectious pathogen or prion. The principal clinical features of Creutzfeldt-Jakob disease are dementia, pyramidal and extrapyramidal symptoms and signs, cerebellar dysfunction, and myoclonus. The patient rapidly deteriorates, declines to a vegetative state, becomes comatous, and is ultimately dead within several months. The authors present a case of Creutzfeldt-Jakob disease, proved by clinical findings, typical serial EEG, and pathologic features.
Uneqivocally positive edrophonium tests, both clinically and electrophysiologically, were observed in a classic case of the Lambert-Eaton myasthenic syndrome. A review of the literature revealed that a positive edrophonium response has been reported in a majority of cases of myasthenia gravis (MG) and overlap myasthenic syndrome and in some cases of the Lambert-Eaton myasthenic syndrome, botulism, congenital myasthenic syndrome, drug-induced myasthenic syndrome, the Guillain-Barre syndrome, and amyotrophic lateral sclerosis. From this, we conclude that an unequivocally positive edrophonium test alone is not necessarily diagnostic of MG and that the diagnosis of MG should be based on the clinical features together with edrophonium-responsiveness and other laboratory findings.
We present electrodiagnostic data on 30 patients with inclusion body myositis (IBM) in order to better delineate its electrophysiological features. Comprehensive electromyography (EMG) and nerve conduction studies (NCS) were performed in all cases. Twelve patients had single fiber electromyography (SFEMG). EMG showed abundant short-small motor unit potentials (MUP) with fibrillations and positive sharp waves in 56.6% of patients, and a mixed pattern of large and small MUP in 36.7%. In 6.7%, only "neurogenic" features were seen. NCS were slow in 33.3%. SFEMG revealed a mildly abnormal jitter and a slightly increased fiber density. IBM demonstrates a heterogeneous EMG profile. A pattern of large and small MUP is highly suggestive of IBM but is seen in only about one third of cases.
A 74-year-old man had a paraneoplastic motor neuron disease mimicking amyotrophic lateral sclerosis. He had an elevated erythrocyte sedimentation rate, other laboratory abnormalities, and a previously undiagnosed renal cell carcinoma. Four months after nephrectomy, his strength had improved and he had no fasciculations. Seven other patients with cancer and motor neuron disease improved or stabilized after tumor treatment. Even though it is rare, paraneoplastic motor neuron disease is important to diagnose because it may be treatable.
In recent years, the sural nerve biopsy has become a commonly performed procedure in the diagnostic work-up of patients with peripheral neuropathy. This paper reviews the diagnostic usefulness and limitations of this procedure. Based on 385 sural nerve biopsies, we found clinically helpful or relevant information in 45% of cases. In 24% of cases, specific diagnoses were obtained, among which vasculitic neuropathy was most common.
Sensory nerve conduction velocity (SNCV) over the forearm segment of the superficial radial nerve was studied by an antidromic method in 76 nerves of 50 normal volunteers ranging in age from 16 to 70 years. The mean SNCVs were 53.3 +/- 3.6 m/sec (1 SD) and the mean amplitudes of sensory nerve action potentials were 15.2 +/- 9.8 microV (1 SD). This method of obtaining SNCV over the forearm segment of the superficial radial nerve is easily performed and the findings are consistent.