[Early cerebral lesions in HIV infection. Postmortem radio-pathologic correlations in non-AIDS asymptomatic seropositive patients]. / Lésions cérébrales précoces au cours de l'infection par le VIH. Corrélations radiopathologiques post mortem chez des séropositifs asymptomatiques non SIDA.

In order to evaluate the diagnostic and prognostic value of MRI in the very early stages of HIV infection, we have compared the results of postmortem brain MRI and neuropathological studies in 7 asymptomatic HIV seropositive individuals, 8 seronegative controls with similar cause of death and 6 patients who died of AIDS in the absence of focal cerebral changes (opportunistic infection or tumour). Cerebral atrophy was consistently evaluated by both techniques. Seropositive asymptomatic cases were significantly more atrophic than the seronegative controls and significantly less atrophic than AIDS patients. Small high signal intensity areas in the white matter and basal ganglia were not significantly more frequent in seropositives than in seronegatives. No corresponding lesion was found at neuropathological examination. Diffuse myelin pallor of the cerebral white matter on myelin preparation was somewhat more severe in seropositive asymptomatic cases than in seronegative controls and less than in AIDS cases. However, these differences were not statistically significant. No significant correlation could be found between neuropathological myelin pallor and diffuse signal abnormalities of the white matter on MRI. We conclude that brain abnormalities are present at the early asymptomatic stage of HIV infection. These include vasculitis with opening of the blood brain barrier and consequent myelin pallor and gliosis of the white matter, and moderate brain atrophy. However MRI correlates are discrete or non specific on post mortem examination, and some probably correspond to scars of transient vascular inflammation. It is very unlikely that MRI examination has any diagnostic or prognostic value at the early stages of the disease.

[CMV and VZV encephalitis in AIDS]. / Encéphalites a CMV et VZV au cours du SIDA.

MATERIAL AND METHODS: Eighty patients were followed up prospectively. Histological correlation was obtained in 25 cases. All MRI examinations were performed on at 0.5 Tesla in T1-weighted sequences with and without gadolinium injection, and in axial or frontal T2-weighted spin echo sequences. Histological confirmation was obtained 30 days on average after the last MRI examination. Immunohistochemical stainings were performed in search of CMV, VZV, toxoplasma, HIV antigen and lymphoma. RESULTS: CMV meningoencephalitis was found in 6 cases. In 3 of these it was manifested by atrophy, either isolated or associated with high signal intensity punctiform areas. Histology detected cortical or subcortical microglial nodules. In 2 cases MRI displayed abnormalities of subependymal nodular signals without enhancement, associated with punctiform abnormalities of subcortical signals. Histology showed subependymal foci of necrosis and abnormalities of white matter. In one case, MRI showed a ventriculitis confirmed by histology. VZV meningoencephalitis was diagnosed in 2 cases. MRI displayed abnormal basal ganglia related to meningitis (n = 1). All abnormalities were confirmed at histology. CONCLUSION: Some images (ventriculitis, infarction in basal ganglia, abnormal subependymal signal) would suggest VZV and CMV encephalitis. Other images (abnormalities of punctiform signals or atrophy) are not specific.