The physical examination as a window into autonomic disorders.

Signs of autonomic dysfunction, although at times seemingly mysterious, can contribute to diagnostic clarification and clinical investigation. Even when sophisticated autonomic testing equipment is not readily available, the experienced clinician, through educated observation and inductive reasoning-in conjunction with an intelligently obtained autonomic medical history-can discern much by a careful physical examination. Elements of the autonomic examination include variations in the pulse, postural measurements of blood pressure and heart rate, pupillary light reactions, skin coloration and temperature, patterns of sweating, and other organ-specific physical findings relevant to the individual patient's presentation. Especially important is the often neglected practice of measuring the blood pressure standing up, for orthostatic hypotension cannot be diagnosed by symptoms alone and is a common source of potential morbidity. The examination should be carried out in the context of understanding the syndromic nature of abnormalities of components of the autonomic nervous system.