Neuropathy

Neuropathy is damage to the nerves. Nerves transmit signals within the brain and spinal cord (the central nervous system or CNS), and extend from the CNS to the muscles, skin and organs. The nerves that are outside the CNS are called the peripheral nervous system (PNS). They detect sensations such as pain and control movement.

Symptoms
Peripheral neuropathy usually involves damage to the nerves in the feet or, less commonly, the hands. The symptoms can range from mild tingling and numbness through to excruciating pain that makes it impossible even to wear a pair of socks. Usually both sides of the body are affected equally.

Occasionally the autonomic nervous system can be affected, causing symptoms such as dizziness, diarrhoea and sexual impotence.

Causes and treatments
There are several different causes of nerve damage among people with HIV. Some causes are not linked to having HIV, for example, anyone with diabetes, anyone who consumes large quantities of alcohol and patients with vitamin B12 deficiency.

If medical tests confirm that you have a vitamin B12 deficiency, your doctor may offer supplements of vitamin B12 by injection (tablets are largely ineffective because vitamin B12 is poorly absorbed in the gut). Increasing the vitamin B12 content of your diet may also help a little; foods that are rich in B12 include fish, dairy products, kidney, liver, eggs, beef and pork. Ask to see a dietician at your clinic for more advice.

Some infections can cause neuropathy directly, such as cytomegalovirus (CMV) or HIV itself. These cases are best treated by tackling the underlying cause such as using anti-CMV or anti-HIV drugs, respectively.

Drug-related neuropathy
Among people with HIV, neuropathy is commonly caused by certain medical treatments. It is a significant side effect with several anti-HIV drugs, in particular ddC, ddI, d4T and to a lesser extent 3TC.

It can be caused by other drugs prescribed for people with HIV, such as the antibiotics dapsone and intravenous pentamidine, the anti-Tuberculosis drug isoniazid, and the anti-Kaposi’s sarcoma drugs, vinblasine and vincristine.

If you take more than one of these drugs, the risk of developing neuropathy may be increased. If you have previously had neuropathy caused by something else, such as HIV itself, you may also be more likely to develop neuropathy from taking one or more of these drugs.

If you develop drug-related neuropathy, it is important to discuss this with your doctor to get advice regarding whether you should stop any of your medication or whether there are options to change.

Once the drug has been stopped, the neuropathy may continue to get worse for a couple of weeks, but then it nearly always goes away over time. Later you may be able to get back onto a reduced dose of the drugs without the neuropathy returning.

In the meantime your doctor can prescribe treatments to reduce the pain, such as gabapentin or amitriptyline. In severe cases you may need strong painkillers including opiate agents such as methadone.

Sometimes complementary therapies such as acupuncture and reflexology may be helpful and topical agents like capsacin can benefit some people.