Prolonged sympathetic reflex latency on skin nerves in sporadic cerebellar degeneration.

BACKGROUND Many physiological or pharmacological evaluations of autonomic function have been performed in patients with various types of cerebellar degeneration (CD). Few studies have been done, however, using neurographic recordings in patients with CD, especially of sudomotor or vasoconstrictor nerves. OBJECTIVE To confirm the clinical importance of sympathetic reflex latencies on the skin nerves of patients with various types of CD. DESIGN AND SETTING Case-comparison study at an academic center. PARTICIPANTS We studied 12 patients who had sporadic CD (cerebellar cortical atrophy, olivopontocerebellar atrophy, and Shy-Drager syndrome) and 15 healthy volunteers as controls. METHODS Skin sympathetic nerve activity (SSNA), sympathetic skin response, and skin vasomotor reflex were simultaneously recorded using randomly administered electrical stimuli. RESULTS In controls, SSNA reflex latency ranged from 640 to 864 milliseconds. Patients with cerebellar cortical atrophy exhibited slight but significant (P<.01) prolongation of reflex latency to the onset of reflex bursts. In patients with olivopontocerebellar atrophy, latency to the onset and the peak of reflex bursts was significantly prolonged (P<.001). Patients with Shy-Drager syndrome had no SSNA, sympathetic skin response, or skin vasomotor reflex, even with supramaximal electrical stimuli. CONCLUSIONS Prolonged reflex latency or the absence of reflex bursts on SSNA can be observed in patients with CD with various forms of autonomic dysfunction. The measurement of SSNA reflex latency may be a useful method of evaluating sympathetic function, including the central pathway.