Neuropathy: Painful, Costly -- and Unknown

It can be caused by diabetes, Lyme disease, HIV, injury, cancer drugs, heredity, vitamin B12 deficiency, an excess of vitamin B6 (pyridoxine) and much more. It affects 20 million to 40 million Americans. One study blamed it for $3.4 billion in Medicare claims in 1999.

"For a problem with a lot of impact, not many people are aware of it," says Norman Latov, M.D., director of the Neuropathy Center of Weill Cornell Medical College and medical and scientific director of the Neuropathy Association.

There is no cure for the many types of neuropathy, he says. Still, early recognition of the problem is important. "It's easier to prevent progression than to reverse symptoms," he says.

For instance, if diabetes patients report neuropathy symptoms, their doctors can change their diabetes treatment. That can slow the progress of the nerve damage that makes neuropathy worse. Sometimes, neuropathy symptoms are the first thing to show up when a disease, such as vitamin B12 deficiency, has yet to affect someone in other ways. Neuropathy can signal doctors to look for the cause.

Neuropathy can strike one part of the body or many. Injury, chemotherapy, autoimmune diseases and other systemic illnesses account for about a third of all cases, Dr. Latov says. Diabetes adds another third. Doctors don't know the cause for about one out of three cases.

"In a lot of cases, patients complain about pain but they're ignored when there's no obvious cause for pain," Dr. Latov says. "When nothing is found, they're labeled as hysterical and depressed and treated for depression. And they still have the pain."