A case of aneurysmal subarachnoid hemorrhage associated with bilateral common carotid artery occlusion

Cerebral aneurysm may occur in some cases of major cerebral artery occlusion. However, according to our search of the literature, only four cases of aneurysmal subarchnoid hemorrhage (SAH) associated with bilateral common carotid artery occlusion (CCAO) have been reported in addition to the case we report here with a summary of the previously reported cases. A healthy 82-year-old female was found unconscious and admitted to our hospital where her neurological state was diagnosed as Hunt & Kosnik grade II, World Federation of Neurosurgical Societies grade II. General physical examination yielded no abnormal findings. A computed tomography (CT) scan of the head revealed a subarachnoid hemorrhage (Fisher's classification group 3). An aortogram demonstrated the presence of both vertebral arteries (VA), but the origins of the common carotid arteries (CCAS) were not visible at all. The left vertebral angiogram (VAG) revealed anastomosis between the muscle branch of the VA and the occipital artery, with retrograde blood flow through the external carotid artery supplying the internal carotid artery (ICA). These findings were also visible on the right VAG, but there was severe stenosis of the C2 portion of the right ICA. The right enlarged posterior communicating artery (Pcom) supplied the right ICA. Two saccular aneurysms arising from the junction of the right posterior cerebral artery (PCA) and the enlarged right Pcom and the P2 segment of right PCA, respectively were also observed. Aneurysm formation in this case was probably caused by hemodynamic stress secondary to bilateral CCAO induced by arteriosclerosis.