Serial somatosensory evoked potentials in a patient with familial hypobetalipoproteinemia, and vitamin E deficiency.

Serial somatosensory evoked potentials (SEPs) to median and posterior tibial nerve stimulation in a case with familial heterozygous hypobetalipoproteinemia and vitamin E deficiency were investigated over a period of 4 years. In serial SEPs to posterior tibial nerve stimulation, interpeak latencies between N20 and P2 were delayed even in the early clinical stage, although the peak latency of N20 was normal. N20 latency was delayed when the patient noted paresthesia of the lower extremities. Interpeak latencies between N20 and P2 were progressively prolonged, and finally both peaks disappeared. Progressive dysfunctions of spinal posterior columns and peripheral somatosensory pathways were discovered by serial SEP studies.