Neurally Mediated Hypotension in Fibromyalgia Patients

Recent studies have identified a strong association between chronic fatigue syndrome and several related syndromes of orthostatic intolerance, the most notable of which is (neurally mediated hypo-tension) NMH. Because chronic fatigue is an extremely common symptom in those with fibromyalgia, we sought to determine whether abnormalities in response to upright tilt table testing would be evident in those satisfying the ACR criteria for diagnosis of fibromyalgia.

In this study (Clin Exp Rheumatol 1997;15:239-46), 12 of 20 fibromyalgia patients (60%), but no controls had an abnormal drop in blood pressure during the first 45 minutes (stage 1) of upright 70 degree tilt (P<0.001), and another seven with fibromyalgia developed a drop in blood pressure after the infusion of isoproterenol. All 18 who tolerated upright tilt for more than 10 minutes reported worsening or provocation of their typical widespread fibromyalgia pain during stage 1, whereas controls were asymptomatic.

These results identify a strong association between fibromyalgia and NMH. Further studies will be needed to determine the contribution of autonomic responses to upright stress in the pathophysiology of pain and other symptoms in fibromyalgia, and randomized trails are needed to determine whether the medications available to treat NMH will afford relief to those with fibromyalgia.

This presentation will briefly review current understandings of the physiology of NMH, describe the findings of the recently published fibromyalgia study, and suggest avenues for further research in this area.