Giant basilar artery aneurysms encorporating the posterior cerebral artery: bypass surgery and coil occlusion--two case reports.

Giant aneurysms of the basilar artery are rare. With a diameter of 25 mm or more they are often partially thrombosed and show atheromatous plaques. There are some problems in the treatment especially when the aneurysm is broadbased with bulbous origin encorporating the origin of the posterior cerebral artery (PCA). In many of these cases neither operative clipping alone nor coil embolization alone will be practical without causing an ischemia in the depending brain areas. We will report about two patients with giant aneurysms of the basilar artery involving the origin of the PCA and a combined surgical and interventional neuroradiological approach. Preoperatively both patients showed only mild neurological symptoms (slight left hemiparesis, incomplete hemianopsia). We anastomosed the superficial temporal artery as an extracranial-intracranial bypass end-to-side to the PCA followed by clipping the PCA out of the aneurysm. Next day embolization of the aneurysm with Guglielmi ditachable coils was done. Both patients recovered without complications. An angiographic control showed no more filling of the aneurysm and a free running bypass feeding the PCA. In our opinion this combined approach is an effective method to treat giant aneurysms of the basilar artery which involve the origin of the PCA when clipping alone is impossible.