ABSTRACT
OBJECTIVES: When the supraclinoid portion of internal carotid artery (ICA) is shortened, the anterior clinoid process may have to be partially removed to secure adequate exposure and proximal control of the ICA in posterior communicating artery (P-com) aneurysm. The goal of this study is to investigate, with direct measurement, the relationship between the length of the supraclinoid ICA and aneurysm formation in P-com segment. MATERIAL AND METHODS: The author measured intraoperatively the length of the supraclinoid ICA of patients with P-com aneurysm and compared that of patients with anterior communicating artery (A-com) aneurysm and middle cerebral artery (MCA) bifurcation aneurysm (n=7 each). Additionally, the length of M1 portion of the MCA and A1 portion of the anterior cerebral artery was measured with image analyzer on CT angiogram and also compared that in the same patients. RESULTS: The length of the supraclinoid ICA was 11.6+/-.6 mm and it was similar to that reported at autopsy. The length of the supraclinoid ICA in patients with P-com aneurysm was shorter than that of A-com aneurysm (Student T test, p<0.001) and MCA aneurysm (Student T test, p<0.05). CONCLUSION: It is now generally accepted that aneurysm is acquired lesion, resulting from a complicated interplay of anatomical, hemodynamic, and degenerative factors. These preliminary results suggest when the supraclinoid portion of ICA is shortened, more hemodynamic stress may be produced to anatomically proximally located P-com segment at higher flow rates than other locations of anterior circulation, resulting in aneurysm formation of P-com segment.