Orthostatic intolerance in the Chronic Fatigue Syndrome (CFS)

This study aims to investigate the prevalence and

pathophysiology of orthostatic intolerance (OI) and its

potential contribution to symptoms of a group of unselected

patients with chronic fatigue syndrome (CFS). Seventy five

patients (65 women, 10 men) with CFS were evaluated. During an

initial visit, a clinical suspicion as to the likelihood of

observing laboratory evidence of OI was assigned. Laboratory

investigation consisted of beat-to-beat recordings of heart

rate, blood pressure (Finapres), and stroke volume (impedance

cardiograph) while supine and during 80 degrees head-up tilt

(HUT), during rhythmic deep breathing (6 breaths/min) and

during the Valsalva maneuver.

The responses of 48 age-matched

healthy controls who had no history of OI were used to define

the range of normal responses to these three maneuvers. Forty

percent of patients with CFS had OI during head-up tilt.

Sixteen exhibited neurally-mediated syncope alone, seven

tachycardia (> 35 bpm averaged 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

controls and patients. On average, the duration of disease and

patient age were significantly less and the 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.

Schondorf R, Benoit J, Wein T, Phaneuf D

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