Somatosensory evoked potentials in the neurological sequelae of treated vitamin B12 deficiency.

10 patients with chronic sequelae from vitamin B12 deficiency showed a characteristic profile of abnormalities of median and peroneal somatosensory evoked potentials: mild to moderately slow peripheral conduction to Erb's point, normal conduction or mild slowing across the cervical portion of the median somatosensory evoked potentials, and absence or severe slowing of impulse propagation along the spinal cord with the peroneal somatosensory evoked potentials. These findings are compared with those of other published series of somatosensory evoked potentials in vitamin B12 deficiency. These results shed light on the chronic physiological and anatomical residuals in the nervous system of patients treated for vitamin B12 deficiency.