Autonomic neuropathy is a form of peripheral neuropathy affecting the autonomic portion of the peripheral nervous system.

The peripheral nervous system includes the nerves used for communication to and from the brain and spinal cord (central nervous system) and all other parts of the body, including the internal organs, muscles, skin, and blood vessels.

Autonomic neuropathy involves damage to the nerves supplying the autonomic portion of the peripheral nervous system, which is the portion that supplies the internal organs, blood vessels, and other areas not under voluntary (purposeful) control.

Damage to the autonomic nerves causes abnormal or decreased function of the areas supplied by the affected nerve. For example, damage to the nerves of the gastrointestinal tract causes decreased ability to move food during digestion (decreased gastric motility), resulting in symptoms such as nausea, vomiting, diarrhea or constipation, and abdominal bloating.

Damage to the nerves supplying blood vessels causes problems with regulation of blood pressure and body temperature because dilation of skin capillaries is used to dissipate heat from the body. Damage to other structures causes similar dysfunction.

Autonomic neuropathy is a group of symptoms, not a specific disease. There are many causes. Autonomic neuropathy is associated with the following:

• Other forms of neuropathy
  • Alcoholic neuropathy
  • Diabetic neuropathy
• Parkinson's disease and other multiple systems atrophy
• Disorders involving sclerosis of tissues,
• Surgical or traumatic injury to nerves (such as surgical vagotomy, used to control stomach ulcers and similar disorders)
• Use of anticholinergic medications

• Swollen abdomen
• Heat intolerance, induced by exercise
• Nausea after eating
• Vomiting of undigested food
• Early satiety (feeling full after only a few bites)
• Unintentional weight loss of more than 5% of body weight
• Male impotence
• Diarrhea
• Constipation
• Dizziness that occurs when standing up
• Blood pressure changes with position
• Urinary incontinence (overflow incontinence)
• Difficulty beginning to urinate
• Feeling of incomplete bladder emptying
• Fainting
• Abnormal sweating

Inspection of the abdomen may show distention, and listening to the abdomen with a stethoscope (auscultation) may show abnormal sounds indicating decreased gastric motility.

An eye examination may show sluggish pupil reaction. Examination by touch (palpation) or tapping (percussion) may indicate a distended bladder. Blood pressure examination may show a decrease upon standing (postural hypotension).

Occasionally, other symptoms may indicate disturbed functioning of the autonomic nervous system, including high blood pressure, rapid or slow heart rate, irregular heart rhythms, excessive sweating, difficulty swallowing, or other symptoms.

Special measurements of sweating and heart rate are called "autonomic testing" and can assist in diagnosis and treatment.

• An upper GI (gastrointestinal) examination with small bowel series may show decreased motility, delayed emptying of the stomach, or other abnormalities and may be used to rule out physical obstruction as a cause of vomiting or other GI symptoms.
• An EGD (esophagogastroduodenoscopy) is used to rule out physical obstruction as a cause of GI symptoms.
• An isotope study may indicate gastroparesis (decreased gastric motility).
• A VCUG (voiding cystourethrogram) or other tests of bladder function may show a flaccid bladder (inability of the bladder to contract and empty).

The outcome varies. If the cause can be identified and treated, there is a chance that the nerves associated with autonomic neuropathy may repair or regenerate. The symptoms may improve with treatment, or they may persist or worsen despite treatment.

Most symptoms of autonomic neuropathy are uncomfortable but they are seldom life-threatening.

• Fluid or electrolyte imbalance such as hypokalemia (if excessive vomiting or diarrhea)
• Malnutrition
• Kidney failure (associated with reflux of urine)
• Psychologic/social effects of impotence
• Injuries from falls (associated with postural dizziness)