[Terminovertebral aneurysm arising from basilar artery fenestration].

A case of ruptured middle saccular aneurysm arising from basilar artery fenestration is reported. Defects of the medial wall at the junctures of the fenestrated segments explain the association between vertebrobasilar aneurysms and basilar artery fenestration. A 47 year-old woman had a perimesencephalic subarachnoid hemorrhage. Immediate angiography revealed a ventral vertebrobasilar aneurysm and an endovascular coil occlusion was performed. Embryological development, pathogenesis and therapeutic difficulties are discussed.