American Medical Association Family Medical Guide - American Medical Association [443]
Peripheral Neuropathy
Peripheral neuropathy is damage to the peripheral nerves (the nerves that spread out from the brain and spinal cord). Peripheral neuropathy sometimes occurs as a result of nerve inflammation or as a complication of disorders or conditions such as diabetes, alcoholism, deficiencies of vitamins B or E, AIDS, cancer, kidney disease, or vasculitis (inflammation of blood vessels). Some neuropathies occur as inherited conditions that run in families. Peripheral neuropathy can also be caused by overexposure to some medications (such as the drugs used in chemotherapy; see page 23) and by exposure to toxic chemicals such as insecticides or metals such as lead, arsenic, or mercury.
Symptoms
The symptoms of peripheral neuropathy usually develop gradually over many months and include tingling, numbness, and pain in the feet and later in the hands. The symptoms sometimes spread slowly along the arms and legs to the trunk. In some cases the muscles of the feet, hands, and legs gradually weaken and may atrophy (waste away). When autonomic nerves are affected, impairments in sweating or in bladder, stomach, or bowel function may occur.
Early diagnosis is important because the nerve damage may not be reversible, depending on the cause.
Diagnosis
If your doctor suspects that you have peripheral neuropathy, he or she may refer you to a neurologist (a doctor who specializes in disorders of the nervous system), who will perform a physical examination, test you for signs of muscle weakness and sensory loss, and check your reflexes. He or she may ask you questions about your general health and your family’s health history to determine if a hereditary condition may have caused the nerve damage. The neurologist may perform the following tests: blood tests to check vitamin levels and look for evidence of diabetes, thyroid disease, or inflammatory conditions; a nerve conduction velocity test to measure how fast your nerves transmit impulses; and electromyography to evaluate your nerve and muscle activity. The neurologist also may take a biopsy (sample of tissue) from a small nerve in the ankle called the sural nerve to look for the cause of the neuropathy.
Treatment
The treatment of peripheral neuropathy depends on the cause. For example, a doctor will prescribe vitamins to treat a vitamin deficiency, and corticosteroids or drugs that suppress the immune system to treat an inflammatory disorder such as vasculitis. A person with diabetes will be given medication to lower blood sugar, and a person with abnormal thyroid function will be given medication to correct it. In severe cases of irreversible neuropathy, treatment includes physical therapy, the use of assistive equipment (such as canes, walkers, bath rails, and grab bars), and prevention of sores and infections that could result from injuries caused by the person’s inability to feel pain.
Guillain-Barré Syndrome
Guillain-Barré syndrome, also called acute inflammatory polyneuropathy or idiopathic polyneuritis, is a potentially severe form of peripheral neuropathy (see previous article) resulting from a faulty immune response that can follow a viral infection such as the flu, a cold, mononucleosis (see page 935), or diarrhea. The condition affects the peripheral nerves (the nerves that spread out from the brain and spinal cord). Infection-fighting antibodies and white blood cells of the immune system confuse the nerves with the virus (because the nerves and the virus have a similar molecular structure) and mistakenly attack the nerves. The nerve damage and muscle weakness caused by Guillain-Barré syndrome usually are temporary—most people recover from even severe cases.