Sympathetic skin response in multiple sclerosis.

Somatosympathetic reflex was studied in 29 patients with definite multiple sclerosis (MS) by the non-invasive sympathetic skin response (SSR) method. Abnormal SSRs in 1 or more limbs were noted in 17 patients. Good correlation between the number of absent SSRs and the severity of the disability caused by MS was observed. Delayed or absent SSRs correlated with leg weakness, spinothalamic sensory deficits, and neurogenic bladder. No correlation was noted between signal abnormalities seen on magnetic resonance imaging studies of the hypothalamus or brain stem and absent or delayed SSRs. It is suggested that damage to the central sympathetic fibers in the spinal cord accounts for the absent SSR. The damaged sympathetic fibers are probably located in the lateral columns of the spinal cord.