Sudomotor functional dissection of neurodegenerative diseases

Abstract

We performed a quantitative sudomotor function test using thermal stimulation (40°C) and thyrotropin-releasing hormone (TRH) in 14 patients with multiple system atrophy (MSA), 10 patients with Parkinson's disease (PD), 11 patients with amyotrophic lateral sclerosis (ALS) and in 11 age-matched control subjects. There was thermal sudomotor dysfunction in the lower extremities of the MSA patients. The PD patients failed to increase their local sweating and frequency of sweat expulsions with TRH infusion, in spite of the fact that they still had normal thermal sweating. ALS patients had mild thermoregulatory sweat dysfunction in their lower extremities. These results suggest that in MSA the lesion most responsible for sudomotor dysfunction is the intermediolateral column cells of the spinal cord and postganglionic sympathetic neurons. There may be an impairment of TRH-induced sympathetic responses in PD, and there is a mild postganglionic sympathetic lesion in the lower extremities of ALS patients.