Axonal and demyelinating neuropathy with reversible proximal conduction block,an unusual feature of vitamin B12 deficiency

We report a 35-year-old patient with megaloblastic anemia who presented with features of subacute combined degeneration of the cord. Electrophysiological studies showed features of axonal neuropathy. In addition, there was evidence of prominent focal proximal conduction block in several nerves. After treatment with cyanocobalamin the neuropathy improved, and the peripheral nerve conduction block detected earlier disappeared. Reversible nerve conduction block as a feature of vitamin B12 deficiency in man, to our knowledge, has not been reported in literature, so far. © 1998 John-Wiley & Sons, Inc. Muscle Nerve 21:1341–1343, 1998.