Neuropathy: only annoying?
EDITOR'S NOTE: This weekly column by reporter Bill Kettler answers readers' questions about topics of general medical interest with information provided by doctors from PrimeCare, Jackson County's independent practice association.
I'm 77, and my doctor recently told me I had peripheral neuropathy. When I asked him about it, he said it was nothing to worry about because it grows very slowly. Can someone tell me more about this?
-- Don W., Medford
Peripheral neuropathy is one of those broad terms that doctors apply to a wide range of symptoms such as numbness, stinging, burning or tingling that occur in the feet, and less frequently, in the hands.
Neuropathy may also include muscular weakness, says Dr. Michael Narus, a Medford neurologist. Some patients say they feel like "they've got their socks rolled up under their feet," Narus says. Others say they can't wiggle their toes.
To understand what's happening, it helps to know a little about the human nervous system. Narus likens the whole arrangement to a computer. The central nervous system the brain and spinal cord is like the main processor. The peripheral nervous system all the nerves that come off the spinal cord is like the set of cables that go from the main processor to the muscles, the skin, the joints and everything else.
The tingling and burning start after there has been damage either to the nerves themselves axons or to the insulating sheath myelin around them. The farther the nerves are from the spinal cord, the more likely they are to suffer damage.
Narus says aging is the most common cause, and as many as 2 percent of all people over age 55 may experience some symptoms of peripheral neuropathy.
"All the myelin and the axons are living tissues," he says. "They depend on metabolic function. As our bodies age they don't work as well as they used to."
Researchers have identified more than 100 kinds of neuropathy, each with its own particular cause and symptoms. Some of the more common causes include heredity, diabetes and excessive use of alcohol.
Narus says some causes, such as a vitamin B-12 deficiency or a hypoactive thyroid gland, can be easily treated.
"If you have a treatable neuropathy, it's an easy fix," he says.
Peripheral neuropathy may also occur as a side effect from other medicines, such as powerful chemotherapy drugs.
Unfortunately, only about 10 percent of patients have a cause that responds to treatment. For the others, physicians try to help patients manage their symptoms. Drugs that dampen down the nervous system, such as antidepressants and anticonvulsants, are effective for some people. In a few rare cases, physicians have prescribed methadone to improve quality of life for people with severe symptoms.
Narus says neuropathy can be aggravating for the people who have to cope with it, but the symptoms only rarely lead to more serious medical disability.
"If there's good news in this whole field, it's that most neuropathies are primarily annoying, but not disabling," he says. "I have patients I've followed for 20 years who are in their 80s, and they're still playing golf and skiing and going to the country club - but their feet still burn and sting."
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