Autonomic examination including hand skin temperature and its response to cooling in multiple system atrophy and Parkinson's disease

Abstract

Multiple system atrophy (MSA) clinically is characterized by prominent autonomic dysfunction with combinations of parkinsonian features (MSA-P), cerebellar ataxia (MSA-C) and possible corticospinal symptoms. Autonomic dysfunction in MSA comprises cardinal symptoms of orthostatic hypotension (OH) and urinary incontinence. Additionally, sudomotor and cardiovagal abnormalities are frequently present among the MSA patients. Due to overlapping motor presentations it can be very challenging to distinguish MSA-P from Parkinson's disease (PD). The cardinal MSA autonomic symptoms - OH and urinary incontinence - are of limited assistance while these symptoms are common among the PD patients as well. Autonomic abnormalities for the PD patients may also include constipation, heat or cold intolerance, postprandial hypotension and relative nocturnal hypertension. Previous studies compared hand skin temperature and its response to cooling in subjects with PD and probable MSA. Significant differences regarding hand temperature before and after cooling, as well as kinetics of natural rewarming were found indicating that disturbed neurovascular thermoregulation of distal extremities potentially belongs to MSA autonomic features and could be helpful in clinical differentiation of MSA-P from PD. Up to the present, however, only a minor study sample has been reported. In this study we sought to improve our knowledge about impaired thermoregulation of distal extremities in patients suffering from MSA and PD. Furthermore, the coexistence and possible interrelations for the different subtypes of autonomic dysfunction were assessed in a large cohort of MSA, PD and control patients. In the study 112 MSA, 500 PD and 129 control patients underwent a standard cooling - rewarming procedure, termed ice test (IT). Additionally the subdivision of the patients received peripheral and autonomic nervous systems clinically evaluated. The evaluation included electroneurography and autonomic function tests of heart rate variability, sympathetic skin response and lying-to-standing orthostatic test. The results of this study indicate that the prevalence of pathological IT, the frequencies of gradually increasing temperature decrement and the mean temperature decrement in pathological IT were higher in the MSA group compared with the PD and the control groups, the differences were insufficient for statistical significance. The presence of pathological IT was significantly associated with older patient's age in the PD and the control study groups (p < 0.05). This association was absent for the MSA patients, who themselves were significantly younger (p = 0.001). Significant correlation between the presence of pathological IT and the autonomic symptom of OH was determined (p < 0.001). To conclude, defective thermoregulation of distal extremities is potentially more severe in the MSA patients. So-called ice test however does not differentiate MSA-P and PD reliably. The dysfunction of preganglionic sympathetic neurons might be involved in impaired response to cooling for MSA. The results suggest a pathophysiological affinity between pathological IT and OH, which could be defective sympathetic neurovascular regulation. Specific autonomic testing including IT may help in the differentiation of MSA-P and PD.