Evidence for cardiovascular autonomic nerve dysfunction in multiple sclerosis.

In 21 patients with multiple sclerosis and 20 healthy controls, the following tests of autonomic function were examined: (1) variation in heart rate during deep breathing, (2) the variations in heart rate and systolic blood pressure during a standardised Valsalva manoeuvre, (3) the changes in heart rate and systolic blood pressure during arm ergometry starting at 30 W with increments of 20 W every 3 min. In the control subjects the maximum variation in heart rate from inspiration to expiration was greater than 16 beat/min (range 17-43). In patients with multiple sclerosis, five had a maximum variation in heart rate of less than 13 beat/min which was considered as the lower limit of normal. The Valsalva ratio in the control subjects ranged from 1.33-3.24. Four patients had Valsalva ratios of less than 1.30. In patients with multiple sclerosis the heart rate and systolic blood pressure responses to exercise were attenuated significantly in four and seven subjects respectively. It is concluded that a significant number of patients with multiple sclerosis show evidence of autonomic dysfunction involving the cardiovascular system.