Clinical screening of autonomic dysfunction in multiple sclerosis

BACKGROUND AND PURPOSE: Multiple sclerosis (MS) can affect the autonomic nervous system. Although exercise may be beneficial for people with MS, those with autonomic dysfunction may have altered heart rate responses to exercise. We investigated the hypothesis that the pattern of increase in heart rate on commencement of a simple cycle test would be different in those participants with MS who had been shown to have autonomic dysfunction on laboratory testing compared with both control participants and MS participants not exhibiting autonomic involvement. METHOD: A controlled cohort study with a volunteer sample of 31 adults with MS (26 women, 5 men) with a mean age of 46 +/- 8.00 years (32-60 years), a median Expanded Disability Severity Scale of 3 (1-6) and a mean duration since diagnosis of 10.3 years (0.1-39 years). Thirty-one age-matched, non-disabled, sedentary but healthy adults (26 women, 5 men) with a mean age of 45 +/- 9.5 years (24-57) comprised the control group. Autonomic function was evaluated using continuous heart rate and blood pressure responses to rhythmical deep breathing, the Valsalva manoeuvre, passive postural change and a simple cycle test. RESULTS: There were no significant differences in age, height or weight (p < 0.05) between the two groups or on any of the autonomic test results (p < 0.05). Five participants with MS (16%) had abnormal autonomic function on laboratory testing, two of whom demonstrated an abnormal heart rate response to the cycle test. CONCLUSIONS: It is suggested that physiotherapists monitor the heart rate response to a dynamic exercise test in people with MS prior to prescribing an exercise programme to ensure patients' safety. Should the response appear delayed or attenuated, referral for more formal autonomic laboratory testing is recommended.