Causes include diabetes, amyloidosis, autoimmune disorders, cancer, excessive alcohol consumption, and certain drugs.
People may feel light-headed when they stand and have urination problems, constipation, and vomiting, and men may have erectile dysfunction.
Doctors do a physical examination and various tests to check for autonomic malfunction and possible causes.
The cause is corrected or treated if possible.
(See also Overview of the Autonomic Nervous System Overview of the Autonomic Nervous System The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person’s conscious... read more 
.)
The nervous system Overview of the Nervous System The nervous system has two distinct parts: the central nervous system (the brain and spinal cord) and the peripheral nervous system (the nerves outside the brain and spinal cord). The basic... read more has central and peripheral parts. The central nervous system includes the brain and spinal cord. The peripheral nervous system includes the nerves that connect the body’s tissues with the brain and spinal cord. Peripheral nerves include the following:
Autonomic nerves Overview of the Autonomic Nervous System The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person’s conscious... read more
, which automatically (unconsciously) regulate body processesSomatic nerves, which connect with muscles under voluntary (conscious) control or with sensory receptors in the skin.
Autonomic neuropathies are a type of peripheral neuropathy Overview of the Peripheral Nervous System The peripheral nervous system refers to the parts of the nervous system that are outside the central nervous system, that is, those outside the brain and spinal cord. Thus, the peripheral nervous... read more , a disorder in which peripheral nerves are damaged throughout the body. In autonomic neuropathies, there is much more damage to the autonomic nerves than to the somatic nerves.
Causes of Autonomic Neuropathies
Common causes of autonomic neuropathies include
Autoimmune disorders Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers autoimmune disorders is not known. Symptoms vary depending on... read more (when the immune system misinterprets the body’s tissues as foreign and produces antibodies that attack those tissues)
Viral infections may trigger an autoimmune reaction Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers autoimmune disorders is not known. Symptoms vary depending on... read more that results in destruction of autonomic nerves.
Some of the antibodies produced by the immune system attack the surface of a nerve fiber or the tissues that wrap around the fiber and enable it to conduct impulses quickly and accurately. (These tissues are called the myelin sheath Nerves The peripheral nervous system consists of more than 100 billion nerve cells (neurons) that run throughout the body like strings, making connections with the brain, other parts of the body, and... read more .)
Sometimes antibodies produced by the immune system attack acetylcholine receptors (the part of nerve cells that enables them to respond to acetylcholine). Acetylcholine is one of the chemical messengers (neurotransmitters) used to communicate within the autonomic nervous system.
Other causes of autonomic neuropathies include cancer, drugs, excessive alcohol consumption, and toxins.
Symptoms of Autonomic Neuropathies
A common symptom of autonomic neuropathies is
An excessive decrease in blood pressure when the person stands (orthostatic hypotension Dizziness or Light-Headedness When Standing Up In some people, particularly older people, blood pressure drops excessively when they sit or stand up (a condition called orthostatic or postural hypotension). Symptoms of faintness, light-headedness... read more )
As a result, the person feels light-headed or as if about to faint.
Men may have difficulty initiating and maintaining an erection (erectile dysfunction Erectile Dysfunction (ED) Erectile dysfunction (ED) is the inability to attain or sustain an erection satisfactory for sexual intercourse. (See also Overview of Sexual Dysfunction in Men.) Every man occasionally has... read more ). Some people involuntarily pass urine (urinary incontinence Urinary Incontinence in Adults Urinary incontinence is involuntary loss of urine. Incontinence can occur in both men and women at any age, but it is more common among women and older people, affecting about 30% of older women... read more 
), often because the bladder is overactive. Other people have difficulty emptying the bladder (urine retention Urinary Retention Urinary retention is inability to urinate or incomplete emptying of the bladder. People who have incomplete emptying of the bladder may have urinary frequency or urinary incontinence. If the... read more ) because the bladder is underactive. After eating, some people feel prematurely full or even vomit because the stomach empties slowly (called gastroparesis). Severe constipation Constipation in Adults Constipation is difficult or infrequent bowel movements, hard stool, or a feeling that the rectum is not totally empty after a bowel movement (incomplete evacuation). (See also Constipation... read more may occur.
When somatic nerves are also damaged, people may lose sensation or feel a tingling (pins-and-needles) sensation in the hands and feet, or muscles may become weak.
Diagnosis of Autonomic Neuropathies
A doctor's evaluation
Sometimes blood tests
Doctors may suspect an autonomic disorder based on symptoms. A physical examination and certain tests Diagnosis The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person’s conscious... read more are done to check for signs of autonomic disorders and possible causes (such as diabetes Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Urination and thirst are... read more or amyloidosis Amyloidosis Amyloidosis is a rare disease in which abnormally folded proteins form amyloid fibrils that accumulate in various tissues and organs, sometimes leading to organ dysfunction, organ failure, and... read more 
).
Blood tests are sometimes done to check for antibodies to acetylcholine receptors, which indicate an autoimmune reaction. About half of people with an autonomic neuropathy due to an autoimmune reaction have these antibodies.
Treatment of Autonomic Neuropathies
Treatment of the cause if identified
Sometimes immunosuppressants
For severe symptoms, sometimes immune globulin or plasma exchange
The cause of the autonomic disorder, if identified, is treated. Neuropathies due to an autoimmune reaction are sometimes treated with drugs that suppress the immune system (immunosuppressants) and lessen the reaction. These drugs include azathioprine, cyclophosphamide, and prednisone.
If symptoms are severe, immune globulin (a solution containing many different antibodies obtained from the blood of people with a normal immune system) may be given intravenously, or plasma exchange Plateletpheresis (platelet donation) In addition to normal blood donation and transfusion, special procedures are sometimes used. In plateletpheresis, a donor gives only platelets rather than whole blood. Whole blood is drawn from... read more may be done. In plasma exchange, blood is withdrawn, filtered to remove abnormal antibodies, then returned to the person.
