Neuropathology of AIDS

Virus enters CNS early, may remain subclinical

Neurologic complications develop in up to 50% of cases

Increased risk with lower CD4 counts and high CSF viral load

Primary infection: meningitis (more common), meningoencephalitis

• Affects 10% to 20% of patients during acute infection

• Usually asymptomatic

• HIV-1 RNA detectable in blood/CSF

Symptomatic infection with meningeal signs, dementia, seizures, cranial nerve deficits (especially CN VII)

Giant cell encephalitis/leukoencephalopathy

• Advanced disease associated with AIDS dementia complex (ADC)

• Dysfunction leads to neurocognitive deficits and ultimately dementia

Vacuolar myelopathy

• Most common HIV-associated chronic myelopathy

• Seen in advanced disease (in <10% patients during era of highly active antiretroviral therapy [HAART])

• Often overshadowed by concomitant illnesses

• Weakness, stiff limbs, sensory deficits, sphincter dysfunction

Initiation timing of HAART is an ongoing debate

Meningitis may remain asymptomatic for years

Dementia severity may be correlated to number of infected versus noninfected microglia

Symmetric atrophy with periventricular, deep white matter low attenuation

Encephalitis/encephalopathy: frontal/temporal cortical atrophy +/− ventriculomegaly

Deep white matter: poorly defined grayish hue

Meningitis with mild lymphocytic infiltrates and scanty perivascular inflammation

Giant cell (HIV) encephalitis

• Mainly affects subcortical white matter, thalamic nuclei, brain stem

• Pericapillary aggregates of multinucleated giant cells having generous or scanty cytoplasm; giant cells contain the virus

• Microglial nodules

• Perivascular lymphocyte cuffing

• Reactive vascular endothelial cells

Leukoencephalopathy

• Diffuse demyelination/gliosis

• Infiltrating macrophages, multinucleated giant cells

• Microglial activation

Vacuolar myelopathy

• Vacuolar changes and demyelination affecting posterior columns and lateral corticospinal tracts

GFAP: highlights gliosis

CD68, CD163, HAM56 highlight macrophages, giant cells, microglia

CNS drug and toxin effects

Psychiatric

Infections

Neurodegenerative and demyelinating diseases

Vascular diseases