Myelopathy is a term used to describe any disease that affects the spinal cord, which can result in loss of mobility or sensation. HIV-associated myelopathy is the leading cause of spinal cord disease in HIV (human immunodeficiency virus) patients.
The most common type of myelopathy that affects HIV patients is called vacuolar myelopathy. This form occurs when the fatty tissue called the myelin sheath, which normally covers and protects the nerves, separates from the spinal cord and forms cavities or vacuoles.
Since the myelin sheath is responsible for ensuring that electrical signals from nerves are properly directed to the brain, individuals who have vacuolar myelopathy experience problems with bodily movements and functions.
Although the exact cause of vacuolar myelopathy remains unknown, it has been suggested that HIV itself is responsible for nervous system damage. The disease occurs during the late stages of HIV infection, when the CD4 counts are low. HIV primarily targets the CD4 cells, which are helper T-cells that help fight against disease and infection.
Vacuolar myelopathy has been associated with AIDS dementia complex (ADC), peripheral neuropathies (peripheral nervous system disorder that affects sensations in the hands and feet), and opportunistic nervous system infections and cancers, such as cytomegalovirus (type of herpes virus), progressive multifocal leukoencephalopathy (disease that affects the white matter of the brain), and lymphoma (cancer of the lymph nodes).
Researchers believe that up to 30% of adults with AIDS (acquired immune deficiency syndrome) experience some level of damage to the myelin. The incidence of vacuolar myelopathy may be much higher among HIV-infected children.
Highly active antiretroviral therapy (HAART), which is the standard treatment for HIV and AIDS, has led to a decline in vacuolar myelopathy. Before HAART was introduced, 5-20% of adult HIV patients in clinical studies and 25-55% of adult HIV patients in histological studies were diagnosed with vacuolar myelopathy. Since then, it is estimated that fewer than 10% of AIDS patients develop myelopathy.
The prognosis is poor for individuals who develop vacuolar myelopathy because there is currently no treatment available for the condition. Most patients die within six months of developing symptoms of myelopathy.
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