WHAT IS PERIPHERAL NEUROPATHY?

Peripheral neuropathy (PN) is a disease of the peripheral nerves. These are all the nerves except for the brain and spinal cord.

About 30% of people with HIV develop PN. Some PN is a breakdown of the nerve endings (axons) that send sensations to the brain. Sometimes, PN is damage to the coating of nerve fibers (myelin). This affects the transmission of pain signals to the brain.

PN can be a minor nuisance or a disabling weakness. It usually involves a feeling of pins and needles, burning, stiffness, or numbness in the feet and toes. It can also be tickling sensations, unexplained pain, or sensations that seem more intense than normal. PN symptoms can come and go. Serious PN can cause difficulty walking or standing.

WHAT CAUSES NEUROPATHY?
PN can be caused by HIV infection of nerve cells, by drugs used to treat HIV or other health problems, or other factors. Risk factors for PN include higher HIV viral load, diabetes, age greater than 50, and heavy alcohol use. Other risk factors are the use of cocaine or amphetamines, cancer treatments, thyroid disease, or deficiency of vitamin B12 or vitamin E. Several HIV drugs can cause PN. The most important are the “d” drugs; ddC (Hivid), ddI (Videx), and d4T (Zerit). Hydroxyurea, which is sometimes combined with antiretroviral drugs, increases the risk of PN. Other drugs that can cause PN include:

• dapsone (for pneumocystis pneumonia, PCP)
• isoniazid (INH, for tuberculosis)
• metronidazole (Flagyl, for amoebic dysentery and microsporidiosis), and
• vincristine (Oncovin, for Kaposi’s sarcoma – KS -- and non-Hodgkin’s lymphoma).

• wear looser shoes
• don't walk too far
• don't stand for too long a time
• soak your feet in ice water

• Lamotrigine, an anti-seizure drug, has shown good results in early tests.
• Recombinant human nerve growth factor (rhNGF) was tested for PN but is not being developed.
• Topiramate appears to help repair damaged nerve fibers.
• L-acetyl-carnitine (also called acetyl-l-carnitine or acetyl carnitine) has shown initial good results.
• Prosaptide is also being studied.

• Mild symptoms: Ibuprofen can be used.
• Moderate symptoms: Amitriptyline or nortriptyline can be used. These anti-depressants increase the brain's transmission of nerve signals. Other treatments include neurontin, an anticonvulsant drug, and a gel containing the anesthetic lidocaine.
• Severe symptoms: Narcotic pain relievers such as codeine or methadone can be used. A new drug, pregabalin, was approved in late 2004 but is not yet available.

• B vitamins: Several B vitamins are useful in treating diabetic neuropathy. These include biotin, choline, inositol, and thiamine. They appear to improve nerve function.
• Alpha-lipoic acid may help protect nerves from inflammation.
• Gamma linolenic acid, found in evening primrose oil, has reversed nerve damage in some diabetics.