Observations on recurrent syncope and presyncope in 641 patients

Background Syncope is a common disorder that is potentially disabling and a ffects both young and old. Once neurological, cardiological, and metabolic causes have been excluded, there remains a group in which diagnosis is uncl ear; some may have an autonomic basis. We therefore did a retrospective stu dy on consecutive patients referred to our tertiary referral autonomic cent res between 1992 and 1998 with recurrent syncope and presyncope, in whom no nautonomic causes, before referral, had been sought and excluded. The objec t was to find out whether autonomic investigation helped diagnosis. Methods Data from case notes and from the autonomic database on 641 patient s were analysed. Syncopal patients with a known or provisional diagnosis of autonomic failure were excluded from analysis. The role of screening tests in establishing or excluding an autonomic cause was assessed. Response to additional autonomic tests (such as head-up tilt with or without venepunctu re, and food challenge and exercise) was documented. Some patients underwen t further testing if non-autonomic neurological, psychiatric, and other dis orders were considered. Findings Screening autonomic function tests indicated orthostatic hypotensi on and confirmed chronic autonomic failure in 31 (4.8%) patients. Neurally mediated syncope was diagnosed in 279 (43.5%) on the basis of clinical feat ures and autonomic testing. Most had vasovagal syncope (227 [35%]); other c auses included carotid sinus hypersensitivity (37 [5.8%]), and a group of 1 5 (2.3%) were associated with rarer causes such as micturition and swallowi ng. Miscellaneous cardiovascular causes (systemic hypotension, arrhythmias) , or drugs, contributed to syncope in 53 (8.3%). Non-autonomic neurological causes included vestibular dysfunction (32 [5%]) and epilepsy (11 [1.7%]). In 56 (8.7%) a psychiatric cause was thought to be contributory. In 179 (2 7.9%), syncope was of unknown cause. and (227 autonomic testing. Mos [35%]) ; other causes. Interpretation in recurrent syncope and presyncope, when cardiac, neurologi cal, and metabolic causes have been excluded, autonomic investigation can a id management by making, confirming, or excluding various factors or diagno ses.