Autonomic neuropathy occurs when the nerves that control involuntary bodily functions are damaged. It can affect blood pressure, temperature control, digestion, bladder function and even sexual function.
The nerve damage interferes with the messages sent between the brain and other organs and areas of the autonomic nervous system, such as the heart, blood vessels and sweat glands.
While diabetes is the most common cause of autonomic neuropathy, other health conditions â€” even an infection â€” can be to blame. Some medications also might cause nerve damage. Symptoms and treatment vary based on which nerves are damaged.
Signs and symptoms of autonomic neuropathy depend on the nerves affected. They might include:
Dizziness and fainting when standing, caused by a sudden drop in blood pressure (orthostatic hypertension).
Urinary problems, such as difficulty starting urination, incontinence, difficulty sensing a full bladder and inability to completely empty the bladder, which can lead to urinary tract infections.
Sexual difficulties, including problems achieving or maintaining an erection (erectile dysfunction) or ejaculation problems in men. In women, problems include vaginal dryness, low libido and difficulty reaching orgasm.
Difficulty digesting food, such as feeling full after a few bites of food, loss of appetite, diarrhea, constipation, abdominal bloating, nausea, vomiting, difficulty swallowing and heartburn, all due to changes in digestive function.
Inability to recognize low blood sugar (hypoglycemia), because the warning signals, such as getting shaky, aren't there.
Sweating abnormalities, such as sweating too much or too little, which affect the ability to regulate body temperature.
Sluggish pupil reaction, making it difficult to adjust from light to dark and seeing well when driving at night.
Exercise intolerance, which can occur if your heart rate stays the same instead of adjusting to your activity level.
When to see a doctor
Seek medical care promptly if you begin having any of the signs and symptoms of autonomic neuropathy, particularly if you have diabetes that's poorly controlled.
If you have type 2 diabetes, the American Diabetes Association recommends annual autonomic neuropathy screening beginning when you receive your diagnosis. For people with type 1 diabetes, the association advises annual screening beginning five years after diagnosis.
Autonomic neuropathy is a possible complication of a number of diseases, and the tests you'll need depend on your symptoms and risk factors for autonomic neuropathy.
When you have known risk factors for autonomic neuropathy
If you have conditions that increase your risk of autonomic neuropathy, such as diabetes, and have symptoms of the condition, your doctor will perform a physical exam and ask about your symptoms.
If you are undergoing cancer treatment with a drug known to cause nerve damage, your doctor will check for signs of neuropathy.
When you don't have risk factors for autonomic neuropathy
If you have symptoms of autonomic neuropathy but no risk factors, the diagnosis can be more involved. Your doctor will probably review your medical history, discuss your symptoms and do a physical exam.
Your doctor might recommend tests to evaluate autonomic functions, including:
Breathing tests. These tests measure how your heart rate and blood pressure respond during exercises such as forcefully exhaling (Valsalva maneuver).
Tilt-table test. This test monitors the response of blood pressure and heart rate to changes in posture and position, simulating what occurs when you stand up after lying down. You lie flat on a table, which is then tilted to raise the upper part of your body. Normally, your body narrows blood vessels and increases heart rate to compensate for the drop in blood pressure. This response may be slowed or abnormal if you have autonomic neuropathy.
A simpler test for this response involves standing for a minute, then squatting for a minute and then standing again while blood pressure and heart rate are monitored.
Gastrointestinal tests. Gastric-emptying tests are the most common tests to check for digestive abnormalities such as slow digestion and delayed emptying of the stomach (gastroparesis). These tests are usually done by a doctor who specializes in digestive disorders (gastroenterologist).
Quantitative sudomotor axon reflex test. This test evaluates how the nerves that regulate your sweat glands respond to stimulation. A small electrical current passes through capsules placed on your forearm, upper and lower leg and foot, while a computer analyzes the response of your nerves and sweat glands. You might feel warmth or a tingling sensation during the test.
Thermoregulatory sweat test. You're coated with a powder that changes color when you sweat. While lying in a chamber with a slowly increasing temperature, digital photos document the results as you begin to sweat. Your sweat pattern might help confirm a diagnosis of autonomic neuropathy or suggest other causes for decreased or increased sweating.
Urinalysis and bladder function (urodynamic) tests. If you have bladder or urinary signs and symptoms, a series of urine and bladder tests can evaluate bladder function.
Ultrasound. If you have bladder signs and symptoms, your doctor might do an ultrasound in which high-frequency sound waves create an image of the bladder and other parts of the urinary tract.
Treatment of autonomic neuropathy includes:
Treating the underlying disease. The first goal of treating autonomic neuropathy is to manage the disease or condition damaging your nerves. For example, if the underlying cause is diabetes, you'll need to tightly control blood sugar to prevent autonomic neuropathy from progressing. About half of the time, no underlying cause for autonomic neuropathy is found.
Managing specific symptoms. Some treatments can relieve the symptoms of autonomic neuropathy. Treatment is based on what part of your body is most affected by nerve damage.
Digestive (gastrointestinal) symptoms
Your doctor may recommend:
Diet changes. You might need to increase dietary fiber and fluids. Fiber supplements, such as Metamucil or Citrucel, also might help. Slowly increase fiber to avoid gas and bloating.
Medication to help your stomach empty. A prescription drug called metoclopramide (Reglan) helps your stomach empty faster by increasing the contractions of the digestive tract. This medication can cause drowsiness and isn't advised for long-term use.
Medications to ease constipation. Over-the-counter laxatives can help ease constipation. Ask your doctor how often you should use a laxative.
Medications to ease diarrhea. Antibiotics can help treat diarrhea by preventing excess bacterial growth in the intestines, and over-the-counter antidiarrheal medication might be helpful.
Your doctor may suggest:
Retraining your bladder. Following a schedule of when to drink fluids and when to urinate can help increase your bladder's capacity and retrain your bladder to empty completely at the appropriate times.
Medication to help empty the bladder. Bethanechol (Duvoid) is a medication that helps ensure complete bladder emptying. Possible side effects include headache, abdominal cramping, bloating, nausea and flushing.
Urinary assistance (catheterization). A tube is guided through your urethra to empty your bladder.
Medications that decrease an overactive bladder. These include tolterodine (Detrol), oxybutynin or similar medications. Possible side effects include dry mouth, headache, fatigue, constipation and abdominal pain.
For men with erectile dysfunction, your doctor might recommend:
Medications that enable erections. Drugs such as sildenafil (Viagra, Revatio), vardenafil (Levitra) or tadalafil (Adcirca, Cialis) can help you achieve and maintain an erection. Possible side effects include mild headache, flushing, upset stomach and changes in color vision.
If you have a history of heart disease, arrhythmia, stroke or high blood pressure, use these medications with caution. Also avoid taking these medications if you are taking any type of organic nitrates. Seek immediate medical assistance if you have an erection that lasts longer than four hours.
External vacuum pump. This device helps pull blood into the penis using a hand pump. A tension ring helps keep the blood in place, maintaining the erection for up to 30 minutes.
For women with sexual symptoms, your doctor might recommend:
Vaginal lubricants to decrease dryness and make sexual intercourse more comfortable and enjoyable.
Flibanserin (Addyi) for premenopausal women with low sexual desire.
Heart rhythm and blood pressure symptoms
Autonomic neuropathy can cause a number of heart rate and blood pressure problems. Your doctor might prescribe:
Medications to raise your blood pressure. If you feel faint or dizzy when you stand up, your doctor might suggest fludrocortisone. This medication helps your body retain salt, which helps regulate your blood pressure.
Other drugs that can help raise your blood pressure include midodrine (Orvaten) and pyridostigmine (Mestinon, Regonol). Droxidopa (Northera) also can help raise blood pressure. Midodrine and droxidopa can cause high blood pressure when lying down.
Medication to regulate your heart rate. A class of medications called beta blockers helps to regulate your heart rate if it goes too high with an activity level.
A high-salt, high-fluid diet. If your blood pressure drops when you stand up, a high-salt, high- fluid diet can help maintain your blood pressure. This is generally only recommended for severe cases of blood pressure problems, as this treatment may cause blood pressure that is too high or swelling of the feet, ankles or legs and shouldn't be used in patients with heart failure.
If you sweat too much, your doctor might prescribe:
A medication that decreases perspiration. Glycopyrrolate (Cuvposa, Robinul, Robinul Forte, others) can decrease sweating. Side effects can include diarrhea, dry mouth, urinary retention, blurred vision, changes in heart rate, headache, loss of taste and drowsiness. Glycopyrrolate can also increase the risk of heat-related illness, such as heatstroke, from a reduced ability to sweat.
Surgery to cut the nerves in the sweat glands. It's also possible to remove the sweat glands but only in small areas of increased sweating, such as the palms.