Neuropathy
When the nerves are damaged, it is called neuropathy. Nerve damage can affect:
- The central nervous system, which is the brain and spinal cord
- The outer nerves of the arms, legs, hands and feet. This is the peripheral nervous system. Neuropathy that affects these nerves is called peripheral neuropathy. It can affect movement or sensation, for example.
- The nerves that control automatic body functions such as blood flow, breathing or the working of organs. This is the autonomic nervous system. When neuropathy affects these nerves, it is called autonomic neuropathy. It can affect the bowels and bladder, for example.
A third to a half of the people who have symptoms of HIV infection have peripheral neuropathy. Peripheral neuropathy is more common among people who use drugs that are injected. Some types of anti-HIV drugs Ð nucleoside analogue reverse transcriptase inhibitor (NRTI) Ð can cause peripheral neuropathy. Both children and adults with AIDS can get peripheral neuropathy. Children usually have less serious symptoms.
Symptoms
The main sign of nerve damage is tingling, burning or extreme sensitivity to touch. This sensitivity can be so intense that wearing socks or shoes or even lying under a sheet or covers is unbearable. Such symptoms usually affect both sides of the body equally.
The symptoms often start with the bottoms of the feet and then rise upward. Many people only complain when their symptoms reach the ankles. If the neuropathy affects the autonomic nervous system, a person may feel dizzy, have diarrhea or not able to perform sexually.
Causes
Neuropathy is sometimes due to the direct effects of HIV on the nerves. This is especially so in autonomic neuropathy.
It can also be caused by infections or tumors that affect the nerves. Neuropathy can also be caused by:
- Some prescription drugs
- Some anti-HIV drugs. The drugs most likely to cause neuropathy are ddI (didanosine, Videx¨ or VidexEC¨) and d4T (stravudine or Zerit¨). Other nucleoside reverse transcriptase inhibitors (NRTIs), protease inhibitors or non-nucleoside reverse transcriptase inhibitors donÕt seem to cause neuropathy.
- Some drugs used to treat parasites, infections, syphilis or other viruses such as cytomegalovirus. These include isoniazid, vincristine (Oncovin¨), lithium carbonate (Camolit¨, Liskonum¨ or Priadel¨), dapsone, metronidazole (Flagyl¨, Flagyl S¨ or Metrolyl¨) and thalidomide.
- Some recreational drugs, such as heroin, cocaine or amphetamines (speed)
- Alcoholism
- Diabetes
Neuropathy is sometimes due to the direct effects of HIV on the nerves. This is especially so in autonomic neuropathy.
It can also be caused by infections or tumors that affect the nerves. Neuropathy can also be caused by:
- Some prescription drugs
- Some anti-HIV drugs. The drugs most likely to cause neuropathy are ddI (didanosine, Videx¨ or VidexEC¨) and d4T (stravudine or Zerit¨). Other nucleoside reverse transcriptase inhibitors (NRTIs), protease inhibitors or non-nucleoside reverse transcriptase inhibitors donÕt seem to cause neuropathy.
- Some drugs used to treat parasites, infections, syphilis or other viruses such as cytomegalovirus. These include isoniazid, vincristine (Oncovin¨), lithium carbonate (Camolit¨, Liskonum¨ or Priadel¨), dapsone, metronidazole (Flagyl¨, Flagyl S¨ or Metrolyl¨) and thalidomide.
- Some recreational drugs, such as heroin, cocaine or amphetamines (speed)
- Alcoholism
- Diabetes
- A lack of B vitamins, especially B12.
Risk Factors
People with the following factors may be at a greater risk of developing neuropathy:
- Being Caucasian
- Drinking a lot of alcohol
- Having a CD4 cell count below 100
- Having an AIDS-defining condition
- Having diabetes
- Having had peripheral neuropathy before
- Not eating a good diet
- Older age
- Using drugs that affect the nerves
Diagnosis
Peripheral neuropathy can be diagnosed from the unusual feelings in the feet. A doctor may test a person's reflexes. When the ankle reflexes are weak or absent, it may be a sign of neuropathy.
Other tests may be done on the nerves as well. Electromyography and nerve conduction studies may be done. Electromyography measures the electrical activity of a muscle. A nerve conduction study measures how well nerves send electrical signals to the muscles.
Measuring the amount of lactate in the blood may help to find out if the neuropathy is caused by the HIV itself or by nucleoside drugs. (High lactate levels have been linked to neuropathy caused by NRTIs.)
Treatment
Treating neuropathy usually focuses on getting rid of the symptoms. In mild cases, pain relievers such as aspirin or ibuprofen may do the trick. People with severe symptoms may need strong painkillers such a methadone or shots of fentanyl.
If the symptoms are bad, some types of drugs normally used to treat depression may help. These include amitriptyline, nortriptyline (Allegron), doxepin (Sinequan) and desipramine may help. They are usually given in low doses first. It can take a couple of weeks before they start to work. Sometimes these drugs cause dry mouth, difficulty urinating, high blood pressure and sleepiness. They should be used with care in people with dementia. These drugs can cause confusion and hallucinations.
If the neuropathy is caused by a drug such as ddI, the symptoms usually show up after a few weeks on the drug. A person experiencing neuropathy may be advised to take a lower dose of the drug or stop it entirely. Even when the drug is stopped, symptoms may go on for several weeks before slowly going away. People who stop taking drug therapies because of neuropathy often find that they can later take lower doses of the drugs without problems.
A lack of vitamin B12 can cause of neuropathy. Many people with HIV have this. Signs of a lack of vitamin B12, include fatigue, poor memory and anemia. A full B complex pill may be taken to prevent this. Taking too much vitamin B6 may cause nerve damage.
