Occlusion of the top of the basilar artery causes infarctions in supra- and infra-tentorial regions (thalamus, occipito-temporal lobes, rostral trunk and cerebellum) with characteristic clinical and radiological manifestations. We studied 17 patients with this syndrome whose clinical data and neurological images led us to classify them into four groups: type I (2 patients, 12%), showing mainly alterations in consciousness and ocular motricity, and bilateral thalamic infarction; type II (6 patients, 35%), with campimetric manifestations and uni- or bilateral ischemia of the occipito-temporal lobes; type III (5 patients, 29%), with associated corticospinal deficits and lacunar images in the rostral brainstem; and type IV (4 patients, 24%) with symptoms of and neuro-images revealing lesions in the cerebellum. The proposed classification is an attempt to facilitate diagnosis by neuro-imaging and to group patients according to prognosis.