Central conduction and autonomic nervous function in HMSN I.

CNS conduction and autonomic nervous function were investigated in 15 patients with HMSN I. Central motor conduction time (CMCT) was estimated with magnetic brain stimulation and electrical nerve root stimulation. Somatosensory evoked potential (SEP) and visual evoked potential (VEP) were used for assessment of central sensory and visual conduction. Autonomic effector organ functions were assessed with the R-R variation test for parasympathetic function, and the sympathetic skin response test (SSR) for skin sympathetic sudomotor activity. Five of the patients had prolonged CMCT. Central sensory conduction was normal in 3, and slightly prolonged in 1 of the patients, but could not be estimated in 11 due to lack of response from the cervical recording. VEP was abnormal in 2 patients. R-R variations during normal breathing were low in 8 of 15 patients, and low also during deep breathing in 1 of 15. The SSR test was pathological in 5 of 15 patients. Thus, impaired central conduction and/or autonomic dysfunction was not an uncommon finding in patients with HMSN I.