brain, spinal cord, and nerve disorders
Overview of the Autonomic Nervous System
Diagnosis of Autonomic Disorders
A doctor's evaluation Tests to determine how blood pressure changes during certain maneuvers Electrocardiography Sweat testing During the physical examination, doctors can check for signs of autonomic disorders, such as orthostatic hypotension. For example, they measure blood pressure and heart rate while a person is lying down or sitting and after the person stands to check how blood pressure changes when position is changed. When a person stands up, gravity makes it harder for blood from the legs to get back to the heart. Thus, blood pressure decreases. To compensate, the heart pumps harder, and the heart rate increases. However, the changes in heart rate and blood pressure are slight and brief. If the changes are larger or last longer, the person may have orthostatic hypotension. Blood pressure is also measured continuously while the person does a Valsalva maneuver (forcefully trying to exhale without letting air escape through the nose or mouth—similar to straining during a bowel movement). Electrocardiography is done to determine whether the heart rate changes as it normally does during deep breathing and the Valsalva maneuver. Tilt Table Testing None The tilt table test and the Valsalva maneuver, done together, can help doctors determine whether a decrease in blood pressure is due to an autonomic nervous system disorder. Doctors examine the pupils for abnormal responses or lack of response to changes in light. Sweat testingis also done. For one sweat test, the sweat glands are stimulated by electrodes that are filled with acetylcholine and placed on the legs and forearm. Then, the volume of sweat is measured to determine whether sweat production is normal. A slight burning sensation may be felt during the test. In thethermoregulatory sweat test,a dye is applied to the skin, and a person is placed in a closed, heated compartment to stimulate sweating. Sweat causes the dye to change color. Doctors can then evaluate the pattern of sweat loss, which may help them determine the cause of the autonomic nervous system disorder. Other tests, including blood tests, may be done to check for disorders that can cause the autonomic disorder. 