Pure autonomic failure is dysfunction of many of the processes controlled by the autonomic nervous system, such as blood pressure. It is not fatal.

• The cause is usually unknown but sometimes is an autoimmune disorder.
• Blood pressure may decrease when people stand, and they may sweat less and may have eye problems, retain urine, become constipated, or lose control of bowel movements.
• Doctors do a physical examination and tests to look for signs of autonomic malfunction.
• Treatment focuses on relieving symptoms.

In pure autonomic failure (previously called idiopathic orthostatic hypotension or Bradbury-Eggleston syndrome), many processes regulated by the autonomic nervous system malfunction. They malfunction because nerve cells that are part of autonomic pathways are lost. The affected cells are located in clusters (called autonomic ganglia) on either side of the spinal cord or near or in internal organs. The brain and spinal cord are not affected. The peripheral nerves other than the autonomic ganglia are also unaffected. Pure autonomic failure affects more women and tends to begin in a person's 40s or 50s. It does not lead to death.

The cause is usually unknown. Sometimes the cause is an autoimmune disorder, which occurs when the immune system misinterprets the body's tissues (in this case, a part called the A3 acetylcholine receptor antibody) as foreign and attacks them.

The most common symptom is an excessive decrease in blood pressure when a person stands (orthostatic hypotension). People may sweat less and become intolerant of heat. The pupils may not widen (dilate) and narrow (constrict) normally. Vision may be blurred. People may have difficulty emptying the bladder (urine retention). They may be constipated or lose control of bowel movements. Men may have difficulty initiating and maintaining an erection (erectile dysfunction).

Diagnosis and Treatment

Doctors check for signs of autonomic dysfunction during the physical examination and with tests. For example, doctors measure levels of norepinephrine, one of the chemical messengers (neurotransmitters) used by nerve cells to communicate with each other. No test can confirm the diagnosis, so doctors diagnose this disorder by excluding other disorders.

There is no specific treatment, so the focus is on relieving symptoms (see Autonomic Nervous System Disorders: Treatment).

Last full review/revision November 2006 by Phillip Low, MD