The autonomic nervous system (ANS) is responsible for the automatic processes not typically under conscious control, such as digestion, sweating, and certain reflexes. The ANS maintains homeostasis, and monitors and controls the body’s internal, visceral environment.
The ANS is essential to life and responds to the body’s needs. For example, if you are dehydrated, your ANS will constrict your blood vessels, tell your heart to beat faster, maintain blood pressure, and redirect your blood to where it’s needed to go. If you start to exercise, the ANS will tell the heart to pump faster and harder, and redirect blood flow to muscles. If you are hot, the ANS is responsible for sweating and redirecting blood flow to the skin to cool the body back down. In addition to controlling these reflexes, the ANS drives behaviors, and is the part of the nervous system that helps make you thirsty and seek water and shade on a hot day.
Most of the time, autonomic symptoms and signs are not diseases. For example, if you develop tachycardia (when your heart beats faster than normal) or fever from infection, the ANS is doing what it’s supposed to do. There are many other examples of autonomic symptoms that are appropriate – not pathologic.
Sometimes, however, these processes go wrong. When neural control of homeostatic processes malfunction, this is called an autonomic disorder, or a "dysautonomia." Dysautonomia is not a diagnosis: it is just a general term describing malfunction of the ANS.
Patients with autonomic disorders can have symptoms such as lightheadedness with standing, passing out (syncope), constipation, urinary dysfunction, excessively dry mouth, or difficulty tolerating the heat, to name a few. Autonomic disorders cross every field of medicine – patients with autonomic disorders often see urologists, cardiologists, psychiatrists, endocrinologists, gastroenterologists, and many different kinds of physicians. The ANS is often poorly taught in medical training, and many physicians do not feel comfortable or knowledgeable about the ANS or its disorders. It is not unusual for patients to wait months or years before seeing an autonomic specialist. Many autonomic disorders are poorly understood. There is a desperate need for high-quality research and more research support to advance our understanding of the ANS and its disorders.
Autonomic neurologists are subspecialists devoted to the diagnosis and treatment of disorders of the ANS. Autonomic specialists focus on certain autonomic diseases that primarily affect the ANS:
Many other conditions can be affected by the autonomic nervous system, such as constipation, asthma, chronic urticaria (hives) or other allergic conditions, chronic fatigue, and forms of exercise intolerance. Though some of these involve the ANS, autonomic neurologists may not specialize in these disorders, and sometimes other specialists are better positioned to deliver the best care.
In addition to evaluation and management services, we offer comprehensive autonomic reflex testing, often referred to as “Autonomic Function Testing” (AFTs). These tests may help your doctor determine whether the autonomic nervous system is functioning as it should.
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