Autonomic function in patients with hereditary motor and sensory neuropathy type I and Lambert-Eaton myasthenic syndrome.

Noninvasive tests of four autonomic organ systems (vasomotor control, baroreceptor reflexes, sudomotor function and pupillary reflexes) were performed on nine patients with hereditary motor and sensory neuropathy (HMSN) type I and three patients with Lambert-Eaton myasthenic syndrome (LEMS). The results were compared with those of 33 control subjects. Autonomic dysfunction was considered present when at least two of the four organ system tests were abnormal. The three patients with LEMS had abnormal results in two or more different systems, whereas only one of the nine patients with HMSN type I had two abnormal test results. This study demonstrates that autonomic dysfunction is not a common finding in patients with HMSN type I and its presence should alert us to find the cause of this autonomic disorder.