Lhermitte's sign and vitamin B12 deficiency: case report.

CONTEXT AND OBJECTIVE Lhermitte's sign, a classical neurological sign, is a rare manifestation of vitamin B12 deficiency. The aim here was to report on a case of an elderly patient with vitamin B12 deficiency whose first clinical manifestation was the presence of Lhermitte's sign. CASE REPORT We describe an elderly patient with vitamin B12 deficiency who presented cognitive dysfunction, peripheral polyneuropathy and sensory ataxia, and whose first clinical manifestation was the presence of Lhermitte's sign. This sign is one of the rarest manifestations of vitamin B12 deficiency.