The most common spinal cord affliction in AIDS patients is the pathologically defined vacuolar myelopathy, which has been included within the broader clinical designation of the AIDS dementia complex because it is usually accompanied by evidence of concomitant brain dysfunction. The disorder is generally of subacute or gradual onset and progression with painless gait disturbance characterized by ataxia and spasticity. Bladder and bowel difficulty usually follow deterioration of gait, and sensory symptoms and signs are less prominent than gait dysfunction unless there is concomitant neuropathy. Patients do not manifest a distinct sensory or motor “level” as in transverse myelopathies but rather distal loss of large-fiber modalities accompanied by increased deep tendon reflexes (again, in the absence of neuropathy) and Babinski signs. The efficacy of antiretroviral therapy in this subgroup of AIDS dementia complex patients is uncertain, but personal experience suggests that some respond.

Infections by two other retroviruses, human T-lymphotropic viruses types one and two (HTLV-I and HTLV-II), can also cause similar myelopathies and coexist in the same population at risk for HIV-1 or even co-infect the same patient. Diagnosis of these infections is established by serology, and other than the overlap in epidemiology related to sexual or intravenous inoculation, they do not appear to interact in causing CNS disease.

HTLV-I/II myelopathy may be aided by detection of antiviral IgG antibodies in the CSF. MRI is not helpful in distinguishing these from vacuolar myelopathy and usually is negative. In fact, MRI is most useful in detecting and characterizing the segmental myelopathies listed in Table 411-2 .