AUTONOMIC EVALUATION BY MEANS OF STANDARD-TESTS AND POWER SPECTRAL-ANALYSIS IN MULTIPLE-SCLEROSIS

Standard autonomic tests [heart rate response to deep breathing (HRDB) , change in systolic blood pressure due to tilt], and spectral analysi s of heart rate (HR), arterial blood pressure (ABP), and the associate d transfer function analysis (gains and phases) were performed in 20 p atients with multiple sclerosis to determine their diagnostic value. T ransfer function analysis suggested impairment of baroreflex function in 7 patients and an alteration of cardiorespiratory coupling on a bra in stem level in 4 patients. In addition, sympathetic vasomotor outflo w was reduced in 2 patients (spectral ABP measures in the mid frequenc y band) and a decrease of vagal outflow was suggested by abnormal resp iratory HR parameters in another 2. patients. An abnormal HRDB was pre sent in 5 patients and was probably clue to a central alteration (card iorespiratory coupling) in 2 patients and due to diminished respirator y effort in 1 patient. Spectral analysis of both HR and ABP oscillatio ns and their transfer function may considerably improve the pathophysi ological interpretation of cardiovascular autonomic dysfunction in pat ients with central nervous system disease. (C) 1997 John Wiley & Sons, Inc.