Contribution of stereotactic brain biopsies to the diagnosis of presenile dementia.

Precise diagnosis of presenile dementia is a great challenge. The only valuable classification of dementia is the neuropathological one. We present the first series of stereotactic biopsies in 28 presenile patients (18 males, age 39 less than or equal to 58 less than or equal to 69 years, and 10 females, age 23 less than or equal to 52 less than or equal to 66 years). The results demonstrate that the clinical and paraclinical diagnosis (including positron emission tomography scan, neuropsychological examinations, computed tomography scan, electroencephalogram) in only one third of all cases and only in 50% of the Alzheimer and Creutzfeld-Jakob cases. This is very important to be kept in mind when epidemiology or efficacy of drugs are investigated without any neuropathological confirmation.