The role of extracranial carotid abnormalities in the genesis of cerebral aneurysms

The incidence of extracranial internal carotid artery (ICA) abnormalities, namely kinks, coils, and stenoses, was evaluated in a consecutive unselected series of 76 cases of sinlge supratentorial saccular aneurysms submitted to bilateral carotid angiography. These patients were compared with a control group of 120 patients who had undergone either uni- or bilateral carotid angiography for causes other than cerebrovascular occlusive diseases or intracranial arterial aneurysms. Both groups had a total of 152 angiograms. Extracranial carotid abnormalities were significantly higher in aneurysm patients (p<0.001). Arterial kinks and coils were seen on 42 of 152 angiograms in the saccular aneurysm group and 17 of 152 in the control group (p<0.001); however, there was no significant difference regarding ICA stenoses (0.16>p>0.15). In the 76 aneurysm patients, abnormalities were mostly either located or more pronounced on the side opposite the aneurysm (in 22 as opposed to 11 on the same side, p<0.004). It is suggested that extracranial ICA anomalies have a role in the pathogenesis of intracranial arterial aneurysms, possibly by increasing the hemodynamic stress on the side opposite to the carotid lesion. The combination of the hydrodynamic theory, suggested by the present study, with other possible factors, might lead to a better understanding of the mechanism underlying development of human cerebral arterial aneurysms.