[Saccular aneurysm arising from the basilar artery fenestration: a case report].

This patient, 29-year-old female, had an attack of subarachnoid hemorrhage. On admission a cerebral angiogram showed a saccular aneurysm arising from the proximal origin of the fenestrated basilar artery (Fig. 1). The aneurysm was clipped successfully with two steps under a right retromastoidal suboccipital craniectomy (Fig. 2). Association of the fenestrated basilar artery and saccular aneurysm is rare. To our knowledge, 9 cases have been found in the literature and only 4 cases were operated. The authors discussed the pathogenesis and treatment of such aneurysms.