Electrophysiological findings in gastrectomized patients with low serum B12.

Thirty-eight patients with vitamin B12 deficiency after gastric surgery for a benign peptic ulcer were examined electrophysiologically. Thirteen (34 per cent) had electromyographical signs of peripheral nerve involvement and the amplitude of the sensory potentials of the median nerve at wrist (16 patients) was diminished, whereas sensory and motor conduction velocities were normal. Six patients had clinical signs of polyneuropathy. The electrophysiological findings are compatible with slight loss of myelinated nerve fibres. None of the patients had clinical or electromyographical signs of myopathy.