Orthostatic intolerance in the chronic fatigue syndrome

This study aims to investigate the prevalence and pathophysiology of orthos tatic intolerance (OI) and its potential contribution to symptoms of a grou p of unselected patients with chronic fatigue syndrome (CFS). Seventy five patients (65 women, 10 men) with CFS were evaluated. During an initial visi t, a clinical suspicion as to the likelihood of observing laboratory eviden ce of OI was assigned. Laboratory investigation consisted of beat-to-treat recordings of heart race, blood pressure (Finapres), and stroke volume (imp edance cardiograph) while supine and during 80 degrees head-up tilt (HUT), during rhythmic deep breathing (6 breaths/min) and during the Valsalva mane uver. The responses of 48 age-matched healthy controls who had no history o f OI were used to define the range of normal responses to these three maneu vers. forty percent of patients with CFS had OI during head-up tilt. Sixtee n exhibited neurally-mediated syncope alone, seven tachycardia(> 35 bpm ave raged over the whole of the head-up tilt) and six a mixture of tachycardia and syncope. Eight of 48 controls exhibited neurally-mediated syncope. The responses to the Valsalva maneuver and to deep breathing were similar in co ntrols and patients. On average, the duration of disease and patient age we re significantly less and thr: Onset of symptoms was more often subacute in patients with OI than in those without OI. We conclude that there exists a clinically identifiable subgroup of patients with CFS and OI that differs from control subjects and from those with CFS without OI for whom treatment specifically aimed at improving orthostatic tolerance may be indicated. (C ) 1999 Elsevier Science B.V. All rights reserved.