Neurophysiological study of subacute combined degeneration.

Three patients with subacute combined degeneration of the spinal cord due to vitamin B12 deficiency showed a characteristic pattern of abnormalities on neurophysiological tests which corresponded to the clinical signs and symptoms. Peripheral nerve conduction studies showed an axonal degeneration peripheral neuropathy. Brain stem auditory evoked responses were normal; visual evoked responses were mildly abnormal and somatosensory evoked responses were moderately abnormal. These studies shed light on the pathology of this disorder and can aid in its diagnosis.