The Bay Area Reporter - June 16, 2000
Phillip Alden, Survive AIDS Writers Pool

In the central nervous system, the brain sends both conscious and unconscious commands that tell the body how to move, and how to process external sensory stimulus through the five senses: hearing, smell, sight, taste, and touch. The brain also continuously tells the lungs to keep breathing and the heart to keep pumping.

It's important to keep in mind how little we actually know about the central nervous system. We can transplant hearts, lungs, kidneys, and livers. We do not know exactly how the brain functions. We cannot perform a brain transplant.

In initial HIV infection, the virus infects both the bloodstream and the central nervous system at the same time, but HIV doesn't seem to seriously affect the central nervous system and brain until late-stage AIDS disease progression. In the article "The Nervous System in HIV and AIDS" by Dawn McGuire and Yuen T. So, the authors state that "Neurological disease is the first manifestation of symptomatic HIV infection in roughly 10 to 20 percent of persons, while about 30 to 40 percent of patients with advanced HIV disease will have clinically evident neurologic dysfunction during the course of their illness." [1] The article goes on to state that autopsy studies of people with advanced HIV disease show neurologic abnormalities in "75 to 90 percent of cases." That means that most PWAs will experience central nervous system problems over the course of their disease.

Because of antiretroviral therapies, more PWAs are living longer, and as a result they will experience more neurologic problems than their pre-drug predecessors who had a faster mortality rate. It also appears that central nervous system problems may be under-reported because patients often cannot self-evaluate neural disorders.

In the article "Astrocytes: HIV cellular reservoirs and import participants in neuropathogensis" by Ruth Brack-Warner, the author states that these special cells may play a part in both brain infection and HIV regulation in the central nervous system. [2]

Astrocytes are critical cells, and they make up a larger percentage than any other type of cells in the central nervous system. "[Neurons] are dependent on Astrocytes to provide them with essential metabolites and to regulate ion and neurotransmitter concentrations in [neural function]. In addition, Astrocytes maintain the physiological barriers between the [brain], the blood and the cerebral spinal fluid. The article goes on to state that Astrocytes are critical for central nervous system function. The problem is that Astrocytes also promote entry and spread of HIV into the brain. The study of Astrocytes is relatively new, and how to stop them from promoting viral replication without reducing their roll as cellular mediators is still unknown.

Peripheral neuropathy (PN) is the most prominent and easily observed central nervous system illness. It is a disease that commonly affects the nerves in the feet, and is marked by muscle weakness, atrophy, pain, and numbness. Pain levels can range from tolerable to excruciating, and the condition usually gets worse over time. Even though we have not been able to pinpoint the exact cause, it's believed that the condition is caused both by HIV and some of the antiviral drugs, especially the nucleoside analogues; AZT, ddI, ddC, d4T and 3TC. At present, a clinical trial at Stanford University is under way to determine if the drug Lamictal is effective in treating pain caused by neuropathy. Study participants were started on 25 mg of the drug, but for some the dosage had to be increased to 400 mg. The study has shown mixed results so far. Participants who had mild pain showed more improvement than those with severe pain, which seems to indicate that drug is going to be less effective for people whose neural damage is more advanced.

Some AIDS drugs, particularly AZT are capable of crossing the blood-brain barrier intact. A large, short-term study among adults with advanced HIV disease showed improvement in both memory and learning new skills, but there was only a four-month follow-up. Many of the gains in the group may have been negated further down the road.

AIDS dementia complex (ADC) is a serious condition that can be caused by a number of viral agents; fungal infections, toxoplasmosis, human herpes virus-6 and progressive multifocal leukoencephalopathy, (or PML). Dementia is characterized by both subtle and profound changes in behavior, mood, recognition, and tactile sense. People with this condition are often compared to people with severe mental disabilities, and may exhibit antisocial behaviors, yelling or incoherent mumbling, memory loss, or illogical actions. There are no cures at the moment, but there are promising therapies, and the recent developments in psychological medications are an immense help.

Encephalitis is an inflammation of the brain. Most types of encephalitis are caused by viral infection. Symptoms include sudden fever, headaches, sensitivity to light, stiff neck and back, confusion, clumsiness and an unsteady gait.

Meningitis is an infection of the membranes that surround the brain and spinal cord. Many of the symptoms of meningitis are similar to the symptoms of encephalitis.

There are a lot of treatments for these two diseases. Antiviral medications and antibiotics can be used to treat infections, anticonvulsant drugs combat seizures, corticosteroids can reduce brain swelling and inflammation, and sedatives can help ease irritability and restlessness.

The prognosis for encephalitis varies from case to case. Some cases are mild, short, and the patient recovers fully. Other cases can cause permanent neurological damage and death. If meningitis is detected and treated early, most patients recover, but there is a variant that progresses quickly and causes death within 48 hours. Most HIV doctors monitor their more advanced patients so that these two diseases can be detected early and treated quickly and effectively.

Mitochondrial myopathies are a group of neuromuscular diseases involving mitochondria. Mitochondria are small structures found in every living cell in the human body, and they are essentially "power plants" that produce the energy a cell needs to function. Mitochondrial myopathies do the most damage in cells that need a great amount of energy: nerves, the brain, and the muscles. The symptoms of the myopathies include muscle weakness, heart rhythm disturbances, dementia, movement disorders, deafness, blindness, and seizures.

There is no current treatment for mitochondrial myopathies, but physical therapy can improve muscle range and dexterity. Vitamin therapies such as riboflavin, coenzyme Q, vitamins C and K, and carnitine can also be beneficial. The prognosis for mitochondrial myopathies varies greatly, depending on disease progression and the degree of involvement of various organs.

It is important for people living with HIV/AIDS to understand how their central nervous system works, how it gets infected, and how it is treated. It is also important to determine if any of the antiretroviral therapy drugs contribute to central nervous system disease. In these days of emerging debilitating side effects from AIDS drug therapy, we need to know all we can regarding drugs, treatment, and research. We also need to develop more antiviral medications that can cross the blood-brain barrier. Until then, early detection and use of the effective treatments available today is a must for all PWAs.

References

1. The Nervous System in HIV and AIDS; Dawn McGuire and Yuen T. So. The AIDS Knowledge Base -- http://hivinsite.ucsf.edu/akb/1997/05neuro/index.html.

2. Astrocytes: cellular reservoirs and important participants in neuropathogensis; Ruth Brack-Warner. AIDS 14 January 1999, Volume 13, Number 1, The International AIDS Society.

000616
BR000605

Always watch for outdated information. This article first appeared in 2000. This material is designed to support, not replace, the relationship that exists between you and your doctor.

AEGiS presents published material, reprinted with permission and neither endorses nor opposes any material. All information contained on this website, including information relating to health conditions, products, and treatments, is for informational purposes only. It is often presented in summary or aggregate form. It is not meant to be a substitute for the advice provided by your own physician or other medical professionals. Always discuss treatment options with a doctor who specializes in treating HIV.

Copyright ©1980, 2000. AEGiS. All materials appearing on AEGiS are protected by copyright as a collective work or compilation under U.S. copyright and other laws and are the property of AEGiS, or the party credited as the provider of the content. .