Autonomic neuropathy is damage to the part of the nervous system that controls smooth muscle, cardiac muscle and glands. An individual with autonomic neuropathy may experience problems with blood pressure, heart rate, digestion, sweating, bowel and bladder among other issues. Symptoms related to this disorder will vary greatly from individual to individual, depending on the cause and severity. Diabetics are considered to be at higher risk.
Definition & Facts
Autonomic neuropathy isn't a disease in and of itself. It is a cluster of symptoms that is caused by damage to the autonomic nervous system (ANS). The autonomic nervous system controls the sympathetic nervous system, known as the fight or flight system, and the parasympathetic nervous system, known as the resting and digesting system.
The sympathetic response helps the body respond appropriately in an emergency. The parasympathetic system helps the body calm down after an emergency and maintains critical bodily functions. When there is a breakdown in the autonomic nervous system, the body does not react appropriately to environmental cues. These involuntary systems will misfire or not work at all regardless of the body's needs.
Dysfunction in these systems is usually mild but in extreme cases can be severe and life-threatening. Autonomic neuropathy often occurs with other neurological disorders such as peripheral neuropathy.
Symptoms & Complaints
On the other hand, the bowel may speed up, causing diarrhea and potentially bowel incontinence. Nerve changes in the bladder can cause urinary retention. The bladder may never feel completely empty or may become overly full and leak.
Sexual dysfunction can occur in both men and women. Cardiac changes can manifest with alterations in heart rate and blood pressure. It may become difficult to exercise because the heart rate does not adjust with increased effort. Commonly, blood pressure can drop when standing up. This can result in blacking out. An individual is at high risk for injury as a result of falling to the ground.
Pupils may not react as they should, causing difficulty adjusting to light and dark. For diabetics, they may lose the ability to feel the symptoms of oncoming low blood sugar or may not be able to feel the pain of a heart attack. These situations are medical emergencies.
There are many different causes of autonomic neuropathy. Diabetes is the most common cause particularly after a decade or more with the disease. Alcoholism is another common cause. Infections such as Lyme's disease, HIV and some bacteria and viruses can also cause autonomic neuropathy as can autoimmune diseases like lupus, Sjogren's syndrome and rheumatoid arthritis.
Neurological disorders place individuals at higher risk for autonomic neuropathy, like multiple sclerosis, Parkinson's disease and spinal cord injury. Inherited disorders, known as hereditary sensory autonomic neuropathy (HSAN) can cause autonomic neuropathy. Other diseases such as amyloidosis and porphyria can also cause the disorder. And certain drugs can cause autonomic neuropathy, especially certain chemotherapy drugs for cancer.
Diagnosis & Tests
Diabetics and those with known risk factors for autonomic neuropathy can be diagnosed based on symptom reporting alone. If more extensive assessment is required there are several tests and diagnostics available that can be performed. These tests are known as autonomic testing. One simple test is to measure blood pressure changes while lying, sitting or standing. Other tests can measure changes in heart rate while bearing down (the Valsalva maneuver) or during exercise.
A gastroenterologist can test the rate of digestion and stomach emptying. A reflex test can determine problems with the nerves that cause sweating. Thermoregulation may be tested by slowly increasing the environmental temperature and examining the sweat pattern produced. There are exams of the urinary system to evaluate bladder function including an ultrasound of the bladder.
Treatment & Therapy
Treating the root cause of the autonomic neuropathy symptoms is very important to prevent further damage to the autonomic nervous system. For diabetics, this means controlling blood sugar levels through diet and medication. For other diseases it means following the health care provider's prescribed regimen and promptly reporting troubling signs and symptoms.
Some damage to the autonomic nervous system cannot be reversed. Most complaints can be treated with the goal to improve comfort and prevent further complications. Treatment can be complex and all medications can cause side effects, so it is important to discuss treatment with a licensed provider.
- Diet that includes more fiber and fluids
- Smaller, more frequent meals
- Consultation with a dietician
- Metoclopramide, a drug to increase the rate of digestion
- Medications to treat diarrhea
- Laxatives to treat constipation
- Some antidepressants, such as tricyclic antidepressants, to ease abdominal pain
- Sleeping with the head of the bed raised or on several pillows
- A bladder training program
- Intermittent catheterization
- Bethanechol to help complete the emptying of the bladder
- Tolterodine or oxybutynin to treat an overactive bladder
Sexual dysfunction complaints:
- For men, medications such as sildenafil, vardenafil, tadalafil or a device such as the vacuum penile pump device for erectile dysfunction
- For women, a personal lubricant
- A diet high in salt and fluid to raise blood pressure when standing up
- Beta-blockers, a class of drugs to control heart rate
- Medications to increase blood pressure when standing up
- Fludrocortisone, a drug to increase salt retention, to help from feeling dizzy when standing up
- Wearing compression hose first thing in the morning before standing for the first time that day
- A pacemaker for severe cardiac problems
- Medications such as glycopyrrolate to treat overproduction of sweat
Prevention & Prophylaxis