Unusual Intracranial Stent Navigation through the Circle of Willis in a Patient with Recurrent Basilar Tip Aneurysm during Stent-Assisted Coiling. A Case Report.

SUMMARY: We describe a case of unusual Enterprise stent navigation through the Circle of Willis in a patient with a basilar tip aneurysm, left internal carotid artery (ICA) occlusion and previous right ICA stenting. Basilar tip aneurysms are known for their therapeutic challenges, especially when the posterior cerebral arteries (PCAs) are incorporated in the aneurysm neck. This becomes more technically demanding if the vertebral artery does not offer a route for stent navigation. We undertook stent-assisted coiling using the horizontal stenting of posterior cerebral arteries via both the posterior and anterior communicating artery navigation. This was necessary because the vertebral arteries were very tortuous, hence not suitable for stent navigation due to their small size and stenosis at their origin. Another compounding factor was the anatomy of the aneurysm neck in relation to the T-shaped origin of both P1 PCAs from the basilar artery. The right ICA was stented previously and the whole navigation was done through this stented artery as the opposite left ICA was occluded at the bifurcation. In addition, there was no visualized posterior communicating artery (PCOM) on the right side, so following navigation through the anterior communicating artery (ACOM) the left PCOM artery was catheterized to reach the PCAs. After horizontal placement of stent, coiling was performed for the residual aneurysm. The outcome of this intervention revealed successful placement of the Enterprise stent in bilateral posterior cerebral arteries covering the aneurysm. Further coiling of the basilar artery aneurysm was done with a good result. No complication was seen in the angiography suite or later in the course of action. Horizontal stent placement in wide-necked basilar aneurysms can be performed via the PCOM and ACOM arteries.