Peripheral neuropathy, sometimes called peripheral neuritis, is damage to the nerves that connect peripheral (outlying) portions of the body (especially the hands, arms, legs, and feet) to the central nervous system. It may involve only one peripheral nerve (mononeuropathy) or several nerves (polyneuropathy).
Similar to electrical wiring in a house, the body has a highly complex network of nerves made up of bundles of neurons, axons, and dendrites. This network originates in the brain and extends down through the spinal cord.
These nerves branch off at junctures along this pathway to connect each portion of the body to the brain and spinal cord, the central nervous system. Nerves relay necessary information to and from every area, notifying the brain of sensations and external conditions.
The brain, in turn, sends messages back to those areas. With peripheral neuropathy, damage has occurred to the nerves that connect peripheral portions of the body, and the patient feels pain or numbness.
Peripheral neuropathy is not usually considered a disease. It is more often thought of as a symptom of other diseases or conditions, or results from damage caused by the introduction of toxic substances.
There are an estimated two million Americans who suffer from peripheral neuropathy. It becomes more common as people age, and the majority of its victims are 65 years old or older.
Causes and symptoms
The symptoms of peripheral neuropathy depend upon which type of nerve fiber is affected. Sensory nerve fiber damage is more likely to generate various sensations, while motor nerve fiber is more apt to result in weakening and wasting of muscle tissue in the affected area.
It is a condition that develops quite gradually, usually over a period of months or even years. A tingling, prickly sensation in the toes and/or feet is commonly the first sign that is noticed, or there may be numbness in this area.
|Typical peripheral neuropathy symptoms|
Typically this feeling progresses to the lower legs, fingers, hands, arms, and then the trunk of the body in severe cases. As the situation worsens, the tingling sensation feels more like burning or severe discomfort followed by sharp, almost electric shock-like jabs of pain.
These sensations may begin in the toes and feet, and then progress to other affected areas. Later symptoms often include increasing muscle weakness, poor coordination, numbness, and lack of feeling.
Urinary incontinence, diarrhea, constipation, impotence, and postural hypotension (dramatic drops in blood pressure when a person stands) causing dizziness or dangerous falls are other potential negative effects, especially in the elderly.
Peripheral nerves are extended and delicate, easily damaged by a variety of things. Diabetes, alcoholism, diseases of the autoimmune system such as rheumatoid arthritis and lupus, and exposure to health damaging substances can cause peripheral neuropathy.
Chronic liver and kidney disease, thyroid gland imbalances, bacterial or viral infections, and cancer can also cause the damage. Many of the strong anticancer drugs used and certain vitamin deficiencies can also lead to this condition.
Repetitive mechanical actions that put pressure on a particular nerve, like the wrist in carpal-tunnel syndrome, or even inherited abnormalities in the body can cause peripheral neuropathy. However, in many cases no one single reason for this condition can be found.
Guillain-Barre syndrome, also called acute polyneuritis or ascending paralysis, is the only form of peripheral neuropathy that develops differently.
It is a rare and very serious form that is believed to be caused by an autoimmune reaction to infection. Its primary difference from other types of peripheral neuropathy is the terrific rapidity of its onset.
A few rare forms of peripheral neuropathy are inherited. The best known inherited peripheral neuropathy is called Charcot-Marie-Tooth syndrome, or CMT. More than 20 different genes and loci on human chromosomes are now known to be associated with CMT.
Because peripheral neuropathy can be caused by a variety of factors, outcomes vary depending upon the reason for the nerve damage. Some causes, such as vitamin or metabolic deficiencies, can be reversed if caught early; other causes may not be reversible.
Because of these factors, early diagnosis is very important. A neurologist (a doctor who specializes in the nervous system) can diagnose the disorder, try to determine the cause, and assess the extent of the damage.
Sensations of pain, temperature, and touch in various parts of the body are tested by observing the person’s ability to respond to a stimulus. If areas of either hypersensitivity or loss of sensation are found, the boundaries of that feeling are mapped by further testing.
An electromyogram (EMG) tests the electrical activity occurring in muscles and can be used in the diagnostic process. X rays, blood tests, and muscle biopsies are common tests used in determining the cause of peripheral neuropathy.
For example, blood tests that show elevated blood sugar would indicate diabetes, or elevated liver function tests or thyroid levels could indicate liver or thyroid disease.
Treating the underlying cause of the peripheral neuropathy is the key to reversing this condition. For example, diabetics who closely follow their diabetic diet and keep their blood sugar in good control stand the best chance of recovering.
Nutritional deficiencies often related to alcoholism may indicate that the person needs to stop drinking and requires vitamin supplements.
Changes in lifestyle or treatment of the disease condition causing the neuropathy is a highly important facet of reversing, arresting, or simply reducing the symptoms of this uncomfortable condition.
Several simple self-care actions can also relieve symptoms. They include:
- That shoes and stockings should never be tight, but rather loose cotton socks and shoes with good support and padding should be worn. Good foot care includes daily or twice daily foot soaks in tepid to cool water for 15 minutes followed by application of a moistening cream.
- Keeping heavy bed covers off of feet at night either by turning back the covers or using a bed cradle.
- Improving circulation and stimulating regeneration of nerves by frequently massaging the affected areas and walking as much as possible. Hydrotherapy with whirlpool baths may also be used to improve circulation.
- Reducing the intake of caffeine and nicotine, both of which may increase pain.
- Lowering the stress level as much as possible, including taking steps to treat the depression and/or insomnia that often accompany peripheral neuropathy. This may include relaxation therapies or herbal remedies.
Additional therapies thought to provide relief include detoxification and fasting, used to cleanse the system and eliminate poisons that may cause nerve damage.
Control of symptoms is a significant part of the treatment. Pain relief is usually the highest priority. Bodywork such as massage and movement therapies like t'ai chi and qigong may provide relief.
Acupuncture can also be used to promote general health and provide some symptomatic relief. Meditation or yoga may help with relaxation and pain control.
Another alternative approach to peripheral neuropathy is the Feldenkrais method, which works on improving the patient’s sense of balance, and thus helps to prevent falls.
It may take months for the symptoms to subside. Milder pain can be treated with over-the-counter pain medications, including Tylenol or aspirin, while more severe episodes of pain may require pain relievers such as nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, or narcotics such as codeine, Demerol, or morphine.
Sometimes tricyclic antidepressants such as Elavil, Tofranil, or Norpramin are used both for pain relief and the depression that may accompany chronic pain.
Anticonvulsant medications such as Tegretol, Neurontin, or Dilantin are effective against electric like, jabbing pain. Less frequently used drugs include heart and blood pressure drugs such as Mexitil and clonidine, which may alleviate burning sensations.
The acute onset and potentially serious symptoms that can develop in Guillain-Barre syndrome, including nerve and muscle damage affecting swallowing and breathing, make this the type of peripheral neuropathy most likely to require in-patient hospital treatment.
The person suffering from this syndrome must be carefully monitored, may require intubation in order to breathe, and may even have blood plasma removed in order to reduce the number of antibodies in the blood.
Full recovery from peripheral neuropathy is possible if the nerves are not damaged beyond repair. The outcome is dependent upon the extent of damage.
Research is now being conducted that may lead to the manufacture of substances similar to the naturally produced chemicals in the body that stimulate repair of small nerve fibers.
The majority of people suffering from Guillain-Barre syndrome recover completely, often without even receiving medical treatment, but some will develop residual, permanent weakness in the affected area or have further episodes.
The best way to prevent peripheral neuropathy is to treat the underlying disease or eliminate the toxic substance that may cause the symptoms.