[The foramen of Monro--blockage caused by a giant aneurysm of the basilar artery. A case report and review of the literature].

A case of a giant aneurysma of the basilar artery bifurcation with occlusive hydrocephalus due to bilateral foramen of Monro occlusion is reported. The patient presented with progressive neurological deterioration which led to computerized tomography examination and implantation of a ventricular shunt as an emergency procedure. After the patient had recovered to a certain extent, four-vessel angiography was performed that demonstrated a giant basilar tip aneurysm. As the posterior communicating, the posterior cerebral as well as the superior cerebellar arteries originated from the aneurysm sac direct surgical attack as well as endovascular treatment was considered to be impossible. A permanent biventricular-abdominal shunt system was implanted and the patient was discharged. Three weeks later the patient was readmitted comatose after he had suffered a massive subarachnoid hemorrhage from which he finally died. The clinical and radiological signs, the differential-diagnostic considerations as well as the few cases of foramen of Monro occlusion by a giant basilar artery tip aneurysm, presented in the literature so far, are discussed.