Pure Autonomic Failure
(See also Overview of the Autonomic Nervous System.)
Pure autonomic failure is dysfunction of many of the processes controlled by the autonomic nervous system, such as control of blood pressure. It is not fatal.
Pure autonomic failure is caused by abnormal accumulation of alpha-synuclein in the brain.
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. These processes malfunction because the nerve cells that control them malfunction. The affected cells are located in clusters (called autonomic ganglia) on either side of the spinal cord or near or in internal organs. Only the autonomic ganglia are affected. No other nerves are affected, and the brain and spinal cord are not affected.
Pure autonomic failure affects more women and tends to begin in a person’s 40s or 50s. It does not lead to death.
Pure autonomic failure is caused by abnormal accumulation of alpha-synuclein (a protein in the brain that helps nerve cells communicate, but whose normal function is not yet fully understood). Alpha-synuclein also accumulates in people who have Parkinson disease, multiple system atrophy, or Lewy body dementia. Some people who have pure autonomic failure eventually develop multiple system atrophy or Lewy body dementia. REM (rapid eye movement) sleep behavior disorder may occur in people with disorders that involve accumulation of alpha-synuclein, including pure autonomic failure.
The most common symptom of pure autonomic failure 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 (fecal incontinence). Men may have difficulty initiating and maintaining an erection (erectile dysfunction).
Doctors check for signs of autonomic dysfunction during the physical examination and with tests.
If people have orthostatic hypotension due to autonomic dysfunction and REM sleep behavior disorder, they probably have pure autonomic failure.
Doctors may do a blood test to measure levels of norepinephrine. Norepinephrine is one of the chemical messengers (neurotransmitters) used by nerve cells to communicate with each other. This blood test may distinguish pure autonomic failure from other disorders.
There is no specific treatment, so the focus is on relieving symptoms:
Orthostatic hypotension: Measures are taken to stabilize the sudden changes in blood pressure. Consuming more salt and water may increase the volume of blood and thus help increase blood pressure. Standing up slowly may help prevent blood pressure from decreasing too much or too fast when a person stands, as may wearing an abdominal binder or compression stockings. These garments help maintain blood pressure by promoting blood flow from the legs to the heart and thus prevent too much blood from staying (pooling) in the legs. Raising the head of the bed by about 4 inches (10 centimeters) can help prevent blood pressure from increasing too much when the person lies down. Fludrocortisone may be taken by mouth. It helps the body retain salt and water and thus may increase blood pressure as needed when a person stands. Other drugs, such as midodrine or droxidopa, taken by mouth, may also help.
Constipation: A high-fiber diet and stool softeners are recommended. If constipation persists, enemas may be necessary.
Sweating abnormalities: If sweating is reduced or absent, people should avoid warm environments to avoid overheating the body.
Urinary retention: If needed, people can learn to insert a catheter (a thin rubber tube) into the bladder themselves. They insert it several times a day. It is inserted through the urethra, allowing urine in the bladder to drain out. People remove the catheter after the bladder is empty. This measure helps prevent the bladder from stretching and urinary tract infections from developing. Washing the hands, cleansing the area around the urethra, and using a sterile or clean catheter also help prevent infections. Inserting a catheter becomes more difficult as coordination deteriorates. Sometimes drugs such as bethanechol are used to stimulate contractions of the bladder and thus help the bladder empty.
Urinary incontinence: Oxybutynin, mirabegron, tamsulosin, or tolterodine, taken by mouth, may be used to relax the muscles of an overactive bladder. If incontinence persists, using a catheter inserted into the bladder may help. People may learn to insert it themselves.