Excitotoxicity plays an important role in HIV-induced neurodegeneration. HIV infected microglia and perivascular macrophages produce neuronal toxins that can be antagonized by blocking NMDA/AMPA glutamate receptors ⁽³²⁾. Increased CSF glutamate are also observed in patients with HIV dementia. The post-natal period of brain development is particularly vulnerable to excitotoxic injury. In infants, a characteristic feature of HIV infection is impaired brain growth resulting in secondary microcephaly.

MR findings of congenital HIV infection are focal or diffuse hyperintensity in the deep white matter on T2-weighted images and cerebral atrophy (Figure 13). Intracranial calcifications in the basal ganglia and frontal white matter are one of the characteristic findings in HIV infected children ⁽³³⁾. The current understanding of HIV neuropathogenesis implies therapeutic strategies to provide neuroprotection from excitotoxic neuronal injury.

Figure 13. An 11-year-old male with congenital HIV infection.

A. T2WI shows diffusely hyperintense lesions in the white matter with cerebral atrophy.

B. CT shows parenchymal calcifications in bilateral frontal lobes.