Autonomic disturbances including impaired hand thermoregulation in multiple system atrophy and Parkinson's disease

Autonomic dysfunction in multiple system atrophy (MSA) comprises cardinal symptoms of orthostatic hypotension (OH) and urinary incontinence. Additionally, cardiovagal and sudomotor abnormalities can be present. Previous studies compared hand skin temperature and its response to cooling in subjects with probable MSA and Parkinson's disease (PD). Significant differences were found indicating that disturbed thermoregulation belongs to MSA autonomic features and could be helpful in differentiation of MSA from PD. The objective of this study was to improve our knowledge about impaired thermoregulation of distal extremities in MSA with parkinsonian features (MSA-P) and PD and to assess the possible interrelations for the different subtypes of autonomic dysfunction in a large cohort of MSA-P, PD and control patients. The patients underwent a standard cooling-rewarming procedure, termed ice test (IT). Electroneurography, heart rate variability, sympathetic skin response and orthostatic tests were performed for the subdivision of the patients. The prevalence of pathological IT was slightly increased in MSA compared with PD and control groups. The presence of pathological IT was related with older patient's age in PD and control groups significantly (p < 0.05). This relation was absent for the MSA patients, who themselves were significantly younger (p = 0.001). Significant association between the presence of pathological IT and OH was determined (p < 0.001). Defective thermoregulation of distal extremities seems to be more severe in the MSA patients. The dysfunction of preganglionic sympathetic neurons might be involved in impaired response to cooling for MSA. The results suggest pathophysiological affinity of impaired sympathetic neurovascular regulation between pathological IT and OH.