Extraarticular manifestations of the joint hypermobility syndrome may include the peripheral nervous system. The purpose of this study was to investigate autonomic function in patients with this syndrome.

Forty-eight patients with the joint hypermobility syndrome who fulfilled the 1998 Brighton criteria and 30 healthy control subjects answered a clinical questionnaire designed to evaluate the frequency of complaints related to the autonomic nervous system. Next, 27 patients and 21 controls underwent autonomic evaluation: orthostatic testing, cardiovascular vagal and sympathetic functions, catecholamine levels, and adrenoreceptor responsiveness.

Symptoms related to the autonomic nervous system, such as syncope and presyncope, palpitations, chest discomfort, fatigue, and heat intolerance, were significantly more common among patients. Orthostatic hypotension, postural orthostatic tachycardia syndrome, and uncategorized orthostatic intolerance were found in 78% (21/27) of patients compared with in 10% (2/21) of controls. Patients with the syndrome had a greater mean (± SD) drop in systolic blood pressure during hyperventilation than did controls (–11 ± 7 mm Hg vs. –5 ± 5 mm Hg, P = 0.02) and a greater increase in systolic blood pressure after a cold pressor test (19 ± 10 mm Hg vs. 11 ± 13 mm Hg, P = 0.06). Patients with the syndrome also had evidence of α-adrenergic (as assessed by administration of phenylephrine) and β-adrenergic hyperresponsiveness (as assessed by administration of isoproterenol).

The autonomic nervous system–related symptoms of the patients have a pathophysiological basis, which suggests that dysautonomia is an extraarticular manifestation in the joint hypermobility syndrome.

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