Clinical, nerve conduction and nerve biopsy study in vitamin B12 deficiency neurological syndrome with a short-term follow-up.

OBJECTIVE: The frequency and type of neuropathy in vitamin B12 deficiency neurological syndrome (VBDNS) is controversial. This study reports the frequency and type of nerve dysfunction in VBDNS using nerve conduction and sural nerve biopsy and its response to treatment. METHOD: Sixty-six patients with VBDNS diagnosed on the basis of low serum vitamin B12 level and/or megaloblastic bone marrow were subjected to clinical evaluation, hemoglobin, mean corpuscular volume, thyroid function test, HIV serology, and vasculitic profile. Peroneal motor and sural sensory nerve conduction studies were done. Sural nerve biopsy was done in six patients. The patients were treated with cyanocobalamin injection and followed up clinically and with nerve conduction study at 3 and 6 months. RESULTS: The median age of the patients was 46 (12-80) years and 11 patients were females. The duration of symptoms was 1-96 (median 7) months. Clinical features of neuropathy were present in 46 (69.7%) patients and nerve conduction was abnormal in 36 (54.5%) patients. On nerve conduction study, 8 (22.2%) patients had axonal, 4 (11.1%) had demyelinating, and 24 (66.7%) had mixed features. Nerve biopsy revealed acute axonal degeneration in early stage and chronic axonopathy with demyelination in the late stages of disease. The nerve conduction parameters improved at 6 months along with clinical recovery. CONCLUSION: Nearly 70% patients with VBDNS had evidence of neuropathy which is mainly axonal with some demyelinating features.

Quantitative electromyography in dengue-associated muscle dysfunction.

PURPOSE: This study was undertaken to document the muscle involvement in dengue virus infection using quantitative electromyography (QEMG). METHODS: The patients with dengue myopathy were subjected to clinical examination including muscle power, tone, reflex, and sensations. Blood counts, hemoglobin, hematocrit, serum creatine kinase (CK), and electrolytes were determined. The QEMG was performed in the biceps using multimotor unit potential analysis program. Muscle biopsy was done in two patients. At 1 month, their clinical and QEMG analyses were repeated. RESULTS: Thirteen patients whose median age was 34 years were included. Seven patients had severe and six had mild weakness, which was more marked in proximal lower limb muscles. The median CK level was 480 (300-2,477) U/L. Needle EMG did not reveal any spontaneous activity. The motor unit potentials (MUPs) were of normal to short duration, polyphasic with normal interference pattern. The QEMG revealed a significant change in the duration of MUP at 1 month compared with that of baseline. All the patients clinically and biochemically improved after 1 month. Muscle biopsy revealed interstitial hemorrhage with occasional myonecrosis and myophagocytosis without inflammation or vasculitis. CONCLUSIONS: The QEMG in dengue myopathy revealed improvement in the duration of MUP at 1-month follow-up, which paralleled with clinical and CK improvement.