Autonomic neuropathy

Definition

Autonomic neuropathy is a group of symptoms that occur when there is damage to the nerves that manage every day body functions such as blood pressure, heart rate, bowel and bladder emptying, and digestion.

Alternative Names

Neuropathy - autonomic

Causes, incidence, and risk factors

Autonomic neuropathy is a form of peripheral neuropathy. It is a group of symptoms, not a specific disease. There are many causes.

Autonomic neuropathy involves damage to the nerves that run through a part 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.

Damage to the autonomic nerves affects the function of areas connected to the problem nerve. For example, damage to the nerves of the gastrointestinal tract makes it harder to move food during digestion (decreased gastric motility).

Autonomic neuropathy affects the nerves that regulate vital functions, including the heart muscle and smooth muscles.

Damage to the nerves supplying blood vessels causes problems with blood pressure and body temperature.

Autonomic neuropathy is associated with the following:

• Alcoholic neuropathy
• Diabetic neuropathy
• Disorders involving scarring and hardening (sclerosis) tissues
• Guillain Barre syndrome or other diseases that inflame nerves
• HIV and AIDS
• Inherited nerve disorders
• Parkinson's disease
• Surgery or injury involving the nerves
• Use of anticholinergic medications

Symptoms

Symptoms vary depending on the nerves affected. They usually develop gradually over years. Symptoms may include:

Gastrointestinal tract

• Constipation
• Diarrhea
• Feeling full after only a few bites (early satiety)
• Nausea after eating
• Swollen abdomen
• Vomiting of undigested food

Heart and lungs

• Blood pressure changes with position and causes dizziness when standing
• Shortness of breath with activity or exercise

Urinary tract

• Difficulty beginning to urinate
• Feeling of incomplete bladder emptying
• Urinary incontinence (overflow incontinence)

Other symptoms

• Abnormal sweating
• Heat intolerance brought on with activity and exercise
• Male impotence and ejaculation changes in men
• Vaginal dryness and orgasm difficulties in women
• Weight loss without trying

Signs and tests

The doctor will perform a physical exam. A neurological exam may show evidence of injury to other nerves. However, it is very difficult to directly test for autonomic nerve damage.

Signs of autonomic neuropathy include:

• Abnormal sounds in the abdomen
• Decrease of blood pressure upon standing up (postural hypotension)
• Sluggish pupil reaction in the eye
• Swollen belly (abdomen)
• Swollen bladder

Other signs and symptoms that occasionally suggest a problem in the function of the autonomic nervous system include:

• Difficulty swallowing
• Excessive sweating
• Irregular heart rhythms
• High blood pressure
• Rapid or slow heart rate

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

Other tests include:

• Measurement of blood pressure lying down, sitting, and standing
• Measurement of changes in heart rate
• Upper GI
• Esophagogastroduodenoscopy (EGD)
• Isotope study
• Voiding cystourethrogram (VCUG) or other tests of bladder function

Other tests for autonomic neuropathy are based on the suspected cause of the disorder, as suggested by the history, symptoms, and the way symptoms developed.

Treatment

Treatment is supportive and may need to be long-term. Several treatments may be attempted before a successful one is found.

Various strategies may be used to reduce symptoms of light-headedness or dizziness when standing. These include:

• Extra salt in the diet or taking salt tablets to increase fluid volume in blood vessels
• Fludrocortisone or similar medications to help your body retain salt and fluid
• Sleeping with the head raised
• Wearing elastic stockings

Treatments for reduced gastric motility include:

• Medications that increase gastric motility (such as Reglan)
• Sleeping with the head raised
• Small, frequent meals

Diarrhea, constipation, bladder problems, and other symptoms are treated as appropriate. See: Bowel retraining and Neurogenic bladder for information about treatment of these conditions.

Phosphodiesterase type 5 (PDE-5) drugs, such as sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis) may be used for treating impotence. Discuss the use of these medications with your doctor.

Support Groups

Expectations (prognosis)

The outcome varies. If the cause can be found and treated, there is a chance that the nerves may repair or regenerate. The symptoms may improve with treatment, or they may continue or get worse, even with treatment.

Most symptoms of autonomic neuropathy are uncomfortable, but they are rarely life threatening.

Complications

• Fluid or electrolyte imbalance such as low blood potassium (if excessive vomiting or diarrhea)
• Injuries from falls (with postural dizziness)
• Kidney failure (from urine backup)
• Malnutrition
• Psychological/social effects of impotence

Calling your health care provider

Call for an appointment with your health care provider if you have symptoms of autonomic neuropathy. Early symptoms might include:

• Becoming faint or lightheaded when standing
• Changes in bowel, bladder, or sexual function
• Unexplained nausea and vomiting when eating

Early diagnosis and treatment increases the likelihood of controlling symptoms.

Prevention

Preventing or controlling disorders associated with autonomic neuropathy may reduce the risk. For example, diabetics should closely control blood sugar levels. Alcoholics should stop drinking.

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References

Shy ME. Peripheral neuropathies. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 446.

In the clinic. Type 2 diabetes. Ann Intern Med. 2007 Jan 2;146(1):ITC1-15.

Benarroch E, Freeman R, Kaufman H. Autonomic nervous system. In: Goetz CG, eds. Textbook of Clinical Neurology. 3rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 21.