Peripheral neuropathy is a problem with the nerves that carry information to and from the brain and spinal cord to the rest of the body. This can produce pain, loss of sensation, and an inability to control muscles.
- "Peripheral" means nerves further out from the center of the body, distant from the brain and spinal cord (which are called the central nervous system).
- "Neuro" means nerves.
- "Pathy" means abnormal.
Peripheral neuritis; Neuropathy - peripheral; Neuritis - peripheral
Causes, incidence, and risk factors
One set of peripheral nerves relays information from your central nervous system to muscles and other organs. A second set relays information from your skin, joints, and other organs back to your central nervous system.
Peripheral neuropathy means these nerves don't work properly. Peripheral neuropathy may involve damage to a single nerve or nerve group (mononeuropathy), or it may affect multiple nerves (polyneuropathy).
There are many reasons for nerves to malfunction. In many cases, no cause can be found.
Nerve damage can be caused by:
- Diseases that run in families (hereditary disorders), such as:
- Charcot-Marie-Tooth disease
- Friedreich's ataxia
- Diseases that affect the whole body (systemic or metabolic disorders) such as:
- Infections or inflammation, including:
- Exposure to poisonous substances such as:
- Glue sniffing or inhaling other toxic compounds
- Heavy metals (lead, arsenic, and mercury are most common)
- Industrial chemicals -- especially solvents
- Nitrous oxide
- Neuropathy secondary to medications, most commonly:
- Paclitaxel (Taxol)
- Pyridoxine (vitamin B6)
- Miscellaneous causes:
- Compression of a nerve by nearby body structures or by casts, splints, braces, crutches, or other devices
- Decreased oxygen and blood flow (ischemia)
- Prolonged exposure to cold temperatures
- Prolonged pressure on a nerve (such as a long surgery)
- Trauma to a nerve
Peripheral neuropathy is very common. Because there are many types and causes of neuropathy and doctors don't always agree on the definition, the exact incidence is not known.
Some people are more likely to inherit neuropathy.
The symptoms depend on which type of nerve is affected. The three main types of nerves are:
- Nerves that carry sensations (sensory)
- Nerves that control muscles (motor)
- Nerves that carry information to organs and glands (autonomic)
Neuropathy can affect any one or a combination of all three types of nerves. Symptoms also depend on whether the condition affects one nerve, several nerves, or the whole body. When the whole body is affected, it is called polyneuropathy.
Longer nerves are more easily injured than shorter ones, so it is common to have earlier or worse symptoms in the legs and feet than in the hands and arms.
Damage to sensory fibers results in:
With many neuropathies, sensation changes begin in the toes and move toward the center of the body. Other areas become involved as the condition gets worse. Diabetes is a common cause of sensory neuropathy.
Damage to the nerves that run to muscles interferes with muscle control and can cause weakness. Other muscle-related symptoms include:
- Difficulty breathing or swallowing
- Difficulty or inability to move a part of the body (paralysis)
- Falling (from legs buckling or tripping over toes)
- Lack of dexterity (such as being unable to button a shirt)
- Lack of muscle control
- Loss of muscle tissue (muscle atrophy)
- Muscle twitching or cramping
The autonomic nerves regulate involuntary or semivoluntary functions, such as controlling internal organs and blood pressure. Damage to autonomic nerves can cause:
Signs and tests
A detailed history will help your health care provider determine the cause of the neuropathy. A brain and nervous system (neurological) exam may reveal problems with movement, sensation, or organ function. You may also have changes in reflexes and muscle mass.
Blood tests may be done to check for medical conditions such as diabetes, vitamin deficiencies, thyroid problems, or other conditions.
Tests that find and help classify neuropathy may include:
- Addressing the cause (such as diabetes or excess alcohol use)
- Controlling symptoms
- Helping the patient gain maximum independence and self-care ability
- Replacing any vitamin or other deficiencies in the diet
- Stopping injury to the nerve (for example, in cases of neuropathy due to compression such as carpal tunnel syndrome)
Your health care provider may recommend physical therapy, occupational therapy, or orthopedic interventions. For example:
- Exercises and retraining may be used to increase muscle strength and control.
- Wheelchairs, braces, and splints may improve movement or the ability to use an affected arm or leg.
- Surgery may be needed to stop injury to a nerve, such as from carpal tunnel syndrome.
Safety is an important consideration for people with neuropathy. Lack of muscle control and reduced sensation increase the risk of falls and other injuries. You may not notice a potential source of injury because you can't feel it. For example, you may not notice if the water in the bathtub is too hot. For this reason, people with decreased sensation should check their feet or other affected areas daily for bruises, open skin areas, or other injuries they may not have noticed.
Safety measures for people experiencing movement difficulty include:
- Installing railings
- Removing obstacles on floors, such as loose rugs
Safety measures for people having difficulty with sensation include:
- Installing adequate lighting (including night lights)
- Testing water temperature before bathing
- Wearing protective shoes (no open toes, no high heels)
Check shoes often for grit or rough spots that may injure the feet.
Persons with neuropathy are more likely to get new nerve injuries at pressure points such as knees and elbows. They should avoid putting pressure on these areas for too long from leaning on the elbows, crossing the knees, or getting into similar positions.
You may need over-the-counter or prescription pain medications to control pain caused by peripheral neuropathy. Anticonvulsants (phenytoin, carbamazepine, gabapentin, and pregabalin), tricyclic antidepressants (amitriptyline and nortriptyline), or other medications (duloxetine) may reduce the pain. Use the lowest dose possible to avoid side effects.
Adjusting position, using frames to keep bedclothes off tender body parts, or other measures may help reduce pain.
The symptoms of autonomic nerve damage may be difficult to treat or respond poorly to treatment. The following measures may help:
- Wearing elastic stockings and sleeping with the head elevated may help treat low blood pressure that occurs when standing up (postural hypotension). Fludrocortisone or similar medications may also be helpful.
- Taking medications that increase gastric motility (such as metoclopramide), eating small frequent meals, sleeping with the head elevated, or other measures may help.
- Manually expressing urine (pressing over the bladder with the hands), performing intermittent catheterization, or taking medications such as bethanechol may help people with bladder problems.
- Treating impotence, diarrhea, constipation, or other symptoms, as needed.
You can find support group information from The Neuropathy Association - www.neuropathy.org
The outcome depends on the cause of peripheral neuropathy. In cases where a medical condition can be found and treated, the outlook may be excellent. However, in severe neuropathy, nerve damage can be permanent, even if the cause is treated.
For most hereditary neuropathies, there is no cure. Some of these conditions are harmless. Others get worse quickly and may lead to permanent, severe complications.
The inability to feel or notice injuries can lead to infection or damage to the affected part of the body, including:
Other complications include:
Calling your health care provider
Call your health care provider if you have symptoms of peripheral neuropathy. In all cases, early diagnosis and treatment increases the chance of controlling symptoms.
Nerve pain, such as that caused by peripheral neuropathy, can be difficult to control. If your pain is severe, a pain specialist may be able to suggest helpful approaches.
Emergency symptoms include:
- Difficulty breathing
- Difficulty swallowing
- Irregular or rapid heartbeat
If you are going to have a long surgical procedure or will be unable to move for a long period of time, take the appropriate measures (such as padding vulnerable parts of the body) beforehand to reduce the risk of nerve problems. Avoid spending a long period of time in one position (for example, after drinking too much alcohol) or doing certain kinds of repetitive movements (in the case of carpal tunnel syndrome).
Reduce your risk of neuropathy by:
- Drinking alcohol in moderation
- Following a balanced diet
- Keeping good control over diabetes and other medical problems, if you have them
Shy ME. Peripheral neuropathies. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 446.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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