Orthostatic Intolerance Syndrome

ABSTRACT

Orthostatic intolerance is the inability to tolerate an upright posture as a consequence of varying degrees of autonomic nervous system dysfunction. Orthostatic intolerance syndromes can be classified into at least 3 categories 1) orthostatic hypotension, 2) neurally mediated (reflex) syncope, and 3) postural orthostatic tachycardia syndrome. In this review, we discuss the pathophysiology and etiologies of orthostatic hypotension and postural orthostatic tachycardia syndrome, and propose their diagnostic and therapeutic alternatives.