Spinal cord pathology and viral burden in homosexuals and drug users with AIDS

Unless treated with effective antiretroviral therapy many AIDS patients dev elop a characteristic vacuolar myelopathy of the spinal cord associated wit h moderate clinical disability, Opinion is divided as to whether vacuolar m yelopathy is causally linked to HIV myelitis. To investigate this further, spinal cord pathology was assessed in 41 drug users, 33 homosexual men and 16 other patients, all with AIDS. Previous work has shown that HIV encephal itis is more common in Edinburgh drug users than in homosexual men. In the present study HIV myelitis (10% overall) was more common in drug users (17% ) than in homosexual men (3%) (P = 0.05), whereas the incidence of opportun istic Infections (7% v, 9%) and lymphomas (2% v. 6%) was comparable in the two groups, but with a slight trend in the reverse direction, reflecting si milar findings in the brain. However, moderate or severe vacuolar myelopath y was equally represented in both groups (20% of drug users and 21% of homo sexual men). The HIV proviral load, assessed by polymerase chain reaction i n frozen samples of thoracic spinal cord in 37 cases, correlated elated clo sely with the presence of giant cells and/or with immunocytochemical eviden ce of productive HIV infection. In 13 cases, the proviral load was measured in cervical, thoracic and lumbar samples and proved to be uniformly high o r low in individual cases. This study provides no evidence for direct invol vement of HIV: cytomegalovirus, papovavirus or human foamy virus in the pat hogenesis of vacuolar myelopathy.