Autonomic
neuropathy is a group of symptoms caused by damage
to nerves supplying the internal body structures
that regulate functions such as blood pressure,
heart rate, bowel and bladder emptying, and
digestion. Autonomic neuropathy is damage to the nerves that
regulate the part of your nervous system that you
can't control - the nerves that regulate your heart
rate, blood pressure, perspiration and digestion,
among other functions.
Neuropathy is the term for damage to
your nerves. Autonomic neuropathy is among a group
of neuropathies. Neuropathies are often due to
diabetes, although they also have other causes.
Your nerves transmit messages between your brain
and your muscles, blood vessels, skin and internal
organs. Damage to your autonomic nerves results in
faulty communication between your brain and the
parts of your body that your autonomic nervous
system serves.
Signs and symptoms vary depending on which nerves
are affected but can range from
dizziness to trouble
with digestion and urination to sexual difficulties.
Treatment involves addressing the underlying cause,
if possible, and managing the signs and symptoms.
Signs and symptoms
Signs and symptoms of autonomic neuropathy depend on which parts of your
autonomic nervous system are most affected. They may include:
-
A drop in blood
pressure on standing (orthostatic hypotension), which can cause
dizziness and fainting
-
Trouble with
urination, including diminished sensation, overflow incontinence and
inability to empty your bladder completely, which can lead to
urinary tract infections
-
Male impotence
-
Vaginal dryness
and difficulties with arousal and orgasm in women
-
Difficulty
digesting food (gastroparesis), which can cause diarrhea,
constipation, abdominal bloating, nausea, vomiting, heartburn,
feeling full after eating little and loss of appetite
-
Cardiovascular
problems, such as heart rate abnormalities
-
Heat intolerance,
especially during exercise, and abnormal — usually decreased —
sweating
-
Sluggish pupil
reaction to light and dark
-
Exercise
intolerance, which causes your heart rate to remain unchanged
instead of increasing and decreasing in response to your activity
level
-
Lack
of the usual warning signs of low blood sugar (hypoglycemia), which
include shakiness, sweating and palpitations
Causes
Your nervous system is made up of two parts. The core is your central
nervous system — your brain and spinal cord. The rest of your nervous
system, branching off from your spinal cord to the rest of your body, is
your peripheral nervous system.
Part of the peripheral nervous system involves nerves that you
consciously control — such as nerves you use to move your voluntary
muscles. Part is your autonomous nervous system — the nerves that
regulate the part of your nervous system that you can't control, such as
your heart rate, blood pressure and digestion.
Damage to your peripheral nerves is called peripheral neuropathy.
Autonomic neuropathy is a type of peripheral neuropathy.
A
number of conditions can lead to damage of the autonomic nerves. The
most common cause is diabetes. About half of the people who have
diabetes eventually develop some type of neuropathy.
Other causes may include:
-
Alcoholism, a
chronic, progressive disease that can lead to nerve damage
-
Abnormal protein
buildup in organs (amyloidosis), which affects the organs and the
nervous system
-
Autoimmune
diseases, in which your immune system attacks and damages parts of
your body, including your nerves
-
Some tumors, which
can press on nerves and cause direct or remote damage (paraneoplastic
syndrome)
-
Multiple system
atrophy, a degenerative disorder that destroys the nervous system
-
Surgical or
traumatic injury to nerves
-
Other chronic
illnesses such as Parkinson's disease and HIV/AIDS
Risk factors
Having diabetes puts you at high risk of developing nerve damage,
including autonomic neuropathy. The longer you have diabetes, the higher
your risk. Risk is highest for people who've had the disease for more
than 25 years, who are older than 40 and who have difficulty controlling
their blood sugar.
Researchers don't yet understand how having diabetes can cause nerve
damage, but they suspect that high blood sugar plays a role. In fact,
the higher the blood sugar, the greater chance you have of nerve damage.
Controlling blood sugar — keeping it as close to the normal range as
possible — decreases the risk of developing nerve damage or helps keep
it from progressing.
When to seek medical advice
If you have diabetes, a compromised immune system or other chronic
medical condition, see your doctor regularly. Seek medical care promptly
if you begin experiencing any of the signs and symptoms of autonomic
neuropathy.
Screening and diagnosis
Because autonomic neuropathy isn't a single disease, it can be difficult
to diagnose. Often, determining the diagnosis is a matter of ruling out
other causes of the symptoms. Your doctor is likely to take a medical
history, ask for a thorough description of your symptoms and do a
physical exam.
Your doctor also may use a number of tests to aid in diagnosis. These
may include:
-
Autonomic
tests.
These tests measure what happens to your heart rate and blood
pressure and how much you sweat in response to certain maneuvers.
-
Electrocardiogram.
This test can measure the electrical impulses of your heart while
you exhale forcibly into an instrument (Valsalva maneuver). This
maneuver increases the pressure in the blood vessels in your head.
-
Tilt-table
test.
This test monitors your blood pressure and heart rate as you lie
flat on a table that is tilted to raise the upper part of your body.
The tilting places stress on your autonomic nervous system, which
regulates your blood pressure and heart rate. Your doctor can see
how you respond to a situation that's similar to what occurs when
you stand up from lying down. Normally, your body compensates for
the drop in blood pressure that occurs when you stand up by
narrowing your blood vessels and increasing your heart rate.
However, this process may not occur properly in autonomic
neuropathy.
-
Quantitative
sudomotor axon reflex test (QSART).
A small electrical current passes through four capsules placed on
your forearm, foot and leg to activate the nerves that supply your
sweat glands. You'll feel a slight burning sensation during this
test.
-
Thermoregulatory sweat test.
During this test, you're coated with a powder that changes color
when you sweat. You then enter a chamber with slowly increasing
temperature. It causes your body temperature to increase 1 to 1.5
degrees Celsius, which makes most people sweat. Digital photos
document the results. Your sweat pattern may help confirm a
diagnosis of autonomic neuropathy or other causes for decreased
sweating.
-
Ultrasound.
For those with bladder symptoms, high-frequency sound waves create
an image of the bladder and other parts of the urinary tract, which
your doctor can check for abnormalities.
Complications
The possible complications of autonomic neuropathy are many. They may
include:
-
Injuries from
falls caused by lowered blood pressure when you stand
-
Mental and
physical fatigue due to low blood pressure
-
Malnutrition and
weight loss from digestive system difficulties
-
Fluid or
electrolyte imbalance from excessive vomiting or diarrhea, a
condition in which your body loses minerals you need
-
Relationship
problems due to sexual dysfunction
-
Urinary tract
infections
-
Cardiovascular
complications, such as irregular heartbeat (arrhythmia)
-
Kidney failure
from bladder problems that aren't treated properly
Treatment
Treatment for autonomic neuropathy depends on the underlying cause and
the particular signs and symptoms you're experiencing. For example, if
the underlying cause is diabetes, you need to control your blood sugar
to keep it as close to normal as possible. If the underlying cause is an
autoimmune disease, treatment will focus on modulating your immune
system and decreasing inflammation.
The goal of treatment is to manage the underlying condition, repair
nerve damage, if possible, and provide symptom relief.
Medications
The type of medication your doctor may prescribe depends on your
symptoms.
-
Gastrointestinal symptoms.
Your doctor may prescribe metoclopramide (Reglan, Metoclopramide HCL),
which helps your stomach empty more rapidly by increasing the
contractions of the stomach and intestines. Possible side effects
include diarrhea when taken in high doses, drowsiness and
restlessness. Other medications include fiber supplements such as psyllium (Metamucil) or methylcellulose (Citrucel) to relieve
constipation and tricyclic antidepressants such as imipramine (Tofranil)
and amitriptyline (Elavil) for diarrhea and abdominal pain. Possible
side effects of tricyclic antidepressants include orthostatic
hypotension, drowsiness, urinary retention, constipation and dry
mouth.
-
Sexual
dysfunction.
Your doctor may prescribe sildenafil (Viagra), vardenafil (Levitra)
or tadalafil (Cialis) for erectile dysfunction. Possible side
effects include flushing, indigestion and headache. Don't take these
medications if you've had a heart attack, stroke or life-threatening
heart rhythm in the previous six months.Treatmentsfor vaginal
dryness include vaginal estrogen cream (Premarin, Estrace), which
you insert into your vagina with an applicator two or three times a
week, and vaginal estrogen rings (Estring), which releases estrogen
for 90 days.
-
Bladder
problems.
Bethanechol (Urecholine) helps cause urination and emptying of the
bladder. Possible side effects include dizziness, lightheadedness or
fainting. Your doctor may prescribe an antibiotic to clear up a
urinary tract infection.
-
Postural
hypotension.
If you get dizzy or feel faint from a drop in blood pressure when
you get up, your doctor may prescribe medication, a high-salt diet
or support stockings. He or she may prescribe fludrocortisone
acetate (Florinef) to help your body retain salt or recommend a
blood pressure regulator such as midodrine (ProAmatine). Possible
side effects of midodrine include blurred vision, headache and
pounding in the ears. Recently, pyridostigmine (Mestinon) has shown
promising results for treating postural hypotension without causing
high blood pressure while lying down (supine hypertension), a common
problem with midodrine.
-
Sweating.
If autonomic neuropathy affects sweating, it usually causes a
decrease. But if you experience excessive sweating, your doctor may
prescribe a drug that inhibits sweating, such as belladonna
alkaloids (scopolamine, glycopyrrolate) or botulinum toxin type A (Botox).
Possible side effects of belladonna alkaloids include blurred
vision, drowsiness, dizziness and dryness of the mouth, nose and
throat. Botox, given by injection, can cause a skin rash or reaction
at the injection site.
Therapies and procedures
If you have trouble emptying your bladder fully, your doctor may
recommend intermittent urinary catheterization, a procedure in which a
tube is threaded through your urethra to empty your bladder.
Psychotherapy or counseling may be appropriate if you're depressed. Sex
therapy or couples counseling might be helpful if you're experiencing
relationship problems as a result of sexual dysfunction.
Prevention
Taking good care of your health in general and managing any medical
condition that puts you at risk of autonomic neuropathy is the best
prevention. Unfortunately, however, there's no way to prevent
degenerative diseases, such as multiple system atrophy, that increase
the risk of developing autonomic neuropathy. Ways to help prevent
autonomic neuropathy may include:
-
Control your blood
sugar if you have diabetes.
-
Get help if you
have a problem with alcohol.
-
Get appropriate
treatment if you have an autoimmune disease.
-
Achieve and
maintain a healthy weight.
-
Exercise
regularly.
Self-care
If you have trouble digesting food and your symptoms are mild, your
doctor might recommend eating small, frequent meals, avoiding fats and
reducing intake of dietary fiber. For a drop in blood pressure when you
stand up, wearing elastic stockings and sleeping with your head elevated
may help.
Coping skills
Living with a chronic illness or disability presents daily challenges.
Some of these suggestions may make it easier for you to cope:
-
Set priorities.
Decide which tasks you need to do on a given day, such as paying
bills or shopping for groceries, and which can wait until another
time. Stay active, but don't overdo.
-
Seek and accept
support.
Having a support system and a positive attitude can help you cope
with the challenges you face. Ask for or accept help when you need
it. Don't shut yourself off from family and friends.
-
Prepare for
challenging situations.
If something especially stressful is coming up in your life, such as
a move or a new job, knowing what you have to do ahead of time can
help you cope.
-
Talk to a
counselor or therapist.
Depression and impotence are possible complications of autonomic
neuropathy. If you experience either, you may find it helpful to
talk to a counselor or therapist in addition to your primary care
doctor. There are treatments that can help.
