CLINICAL AND PARACLINICAL DIAGNOSIS OF NEUROLOGICAL LESIONS IN AIDS

Seventy to eighty percent of HIV-infected patients exhibit neurologica l disorders at an advanced stage of the disease. In almost 90 % of cas es anatomical examination of brains shows histological lesions, Even w hen often reversible neurological disorders occur during the HIV prima ry infection, most of the manifestations of central nervous system (CN S) damage remains the prerogative of severe immunodepression. The prin cipal CNS lesions associated with HIV infection are presented here wit h the clinical and biological elements that lead to the diagnosis. Cer ebral toxoplasmosis holds a privileged place in these manifestations s ince it responds to an efficient curative and prophylactic treatment w ith a well-codified medical care based on the test treatment. Biologic al data, therefore, only have a contributing value. HIV encephalopathy is frequent, but the dementia syndrome is less frequent than the find ing of associated imaging and pathological anatomy : atrophy and lesio ns of the white matter. Thus, the dementia complex is an elimination d iagnosis. Cryptococcosis must be systematically considered, not only i n patients with meningeal symptoms and headaches, but also with those with isolated fever. The demonstration of cryptococcus and cryptococci c antigen in the CSF has an almost absolute diagnostic value; imaging plays a very small diagnostic role, looking for an exceptional cryptoc occoma. Multifocal progressive leukoencephalopathy benefits from the a ccuracy of MRI, and the diagnosis is usually based on clinical data, M RI and evidence of the virus in the CSF by PCR, even though the only m ean of obtaining full proof is, in theory, stereotaxic biopsy. Primary cerebral lymphoma is the diagnostic alternative to toxoplasmosis. Ste reotaxic biopsy of lesions which resist to a antitoxoplasmic test trea tment is the only mean of asserting this diagnosis for which no biolog ical element is useful, except for rare cases of extension to the meni nges with lymphocytes in the CSF. Cytomegalovirus is anatomically freq uent and clinically non-specific (fever and disorders of conscience). PCR in the CSF has a good diagnostic reliability. Other infections are exceptional, and their diagnosis is often made only by stereotaxic bi opsy.