An asymmetrical fenestration of the basilar artery coexisting with two aneurysms in a patient with subarachnoid haemorrhage: case report and review of the literature.

The vertebrobasilar system is a part of the cerebral arterial circle (circle of Willis), which forms the collateral circulation of the brain. A 75-year-old Caucasian female was admitted to hospital because of a strong headache radiating to the neck. On the basis of a neurological examination, the patient was classified into group III of the Hunt and Hess scale. Subarachnoid haemorrhage and 2 aneurysms of the cerebral arteries were diagnosed during multidetector 64-row computed tomography and angiography. An asymmetrical fenestration of the proximal part of the basilar artery was also observed. The bleeding aneurysm locating at anterior communicating artery was diagnosed and clipped surgically by right fronto-parietal craniotomy. The second aneurysm was located just after the junction of the vertebral arteries on the wall of the basilar artery. The presented case firstly illustrates the asymmetric fenestration of the proximal part of the basilar artery coexisting with subarachnoid haemorrhage and 2 aneurysms of brain arteries. Such observation should increase diagnostic attention in the detection of possible associated aneurysms and can help in preventing complications during all endovascular treatment procedures.