What causes peripheral neuropathy?

There are several possible causes of peripheral neuropathy. Direct injury, such as a broken bone or a severe burn, can cause damage to peripheral nerves. Certain diseases, such as diabetes, arthritis, or lupus, can also result in nerve damage. A lack of essential vitamins and minerals, particular vitamins B12 and E, can contribute to nerve damage. Conversely, taking too much vitamin B6 (more than 200 mg a day) can actually cause this condition.

HIV itself has also been shown to cause nerve damage, usually in people with seriously suppressed immune systems. In most HIV-positive people, however, peripheral neuropathy is a side effect of the medicines they use—certain drugs, including those used to treat HIV and certain AIDS-related infections, can damage peripheral nerves and eventually lead to symptoms of neuropathy.

The most likely reason why certain HIV drugs cause peripheral neuropathy is that they can damage mitochondria—the genetic powerhouses inside cells that help convert nutrients into energy that our cells need. Too much mitochondrial damage, researchers believe, can lead to nerve damage and peripheral neuropathy.

Some of the HIV/AIDS drugs that can cause peripheral neuropathy include:

Hivid (zalcitabine) - sales are to be discontinued before the end of 2006. Videx; Videx EC (didanosine)   Zerit (stavudine) isoniazid (INH; Nydrazid; Tubizid) - for the prevention and treatment of tuberculosis (TB) vincristine (Oncovin; Vincasar) or vinblastine (Velban) - for the treatment of Kaposi's sarcoma (KS) ethambutol (Myambutol) - for the treatment of MAC and other bacterial infections  metronidazole (Flagyl) - for the treatment of amoebas and parasitic infections linezolid (Zyvox) - for the treatment of bacterial infections dapsone - for the treatment of Pneumocystis carinii pneumonia (PCP) and other infections

While peripheral neuropathy is a common side effect of these drugs, this does not mean that all people who take them will experience nerve damage or develop symptoms of neuropathy. It's possible that people who combine these drugs—such as Zerit and Videx, two nucleoside reverse transcriptase inhibitors (NRTIs) that are no longer routinely used together—are at a greater risk of experiencing neuropathy or developing more severe and painful symptoms. Similarly, people who use these HIV medications with other drugs known to cause peripheral neuropathy may also be at an increased risk of this side effect. The risk of peripheral neuropathy may be higher still if these medications are used in people with a history of neuropathy, diabetes, heavy alcohol consumption, poor nutrition, and/or older age.

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