Reappraisal of Lhermitte's sign in multiple sclerosis.

Lhermitte's sign (LS) is strongly linked to multiple sclerosis (MS). Our aim is to reassess its frequency, natural history, various characteristics and neuroradiological correlation in a cohort of MS patients attending our specialized MS clinic and to propose a working definition. Consecutive patients with CDMS and normal controls were interviewed using a structured questionnaire. Cervical MRIs were reviewed when available. There were 300 MS patients and 100 normal controls. Forty-one per cent of the patients and none of the controls reported having LS during the course of their illness. In 53% of those who reported LS, it started in the first three years of the illness and began as an isolated symptom in 64% and was polysymptomatic in 36%. In all patients LS was a short-lasting sensation in all patient who experienced it and was mostly stereotyped in individual patients. Characteristics varied widely between patients. Forty-three patients had cervical MRIs; 17 out of 18 patients who reported LS had abnormalities, whereas only 13 out of the 25 with no LS had abnormalities. The results indicate that LS is highly prevalent in MS, is commonly stereotyped in individual patients, has a variable natural course and correlates significantly with cervical MRI abnormalities. A working definition is proposed.