REDUCED BAROREFLEX SENSITIVITY AND CARDIORESPIRATORY TRANSFER IN AMYOTROPHIC-LATERAL-SCLEROSIS

Introduction: Clinically relevant autonomic disturbances have been rep orted for respirator-dependent ALS patients while subclinical involvem ent may be present in the early course. Methods: Eighteen patients wit h early-stage ALS and 18 age-matched controls were studied by means of standard autonomic tests (heart-rate response to deep breathing and t ilt-table testing), and spectral analysis of heart rate (HR) and arter ial blood pressure (ABP), using the associated transfer function as a measure of baroreflex sensitivity for the mid-frequency band (MF band, 0.05-0.15 Hz) and as a measure of cardiorespiratory transfer for the high-frequency band (HF band, 0.15-0.33 Hz). Results: Mean HR and ABP were increased in ALS, while results of standard autonomic tests were similar for ALS and controls. Transfer function analysis revealed redu ced baroreflex sensitivity and diminished cardiorespiratory transfer d uring normal breathing. Conclusions: Cardiovascular autonomic function s are intact in patients with ALS. There is evidence of sympathetic en hancement and vagal withdrawal, accompanied by reduced baroreflex sens itivity. These findings are similar to those reported for essential hy pertension and may point to a common central autonomic derangement in both disorders. (C) 1998 Elsevier Science Ireland Ltd. All rights rese rved