Treatment of unruptured duplicated middle cerebral artery aneurysm: case report.

Background: Duplication of the middle cerebral artery (DMCA) is an anomalous vessel arising from the internal carotid artery (ICA). The origin of the DMCA lies between the anterior choroidal artery and the distal end of the ICA. The association of cerebral aneurysm and DMCA is rare.

Case Description: In this 63-year-old woman, preoperative angiography and 3-dimensional computed tomography angiography revealed an aneurysm at the origin of the DMCA. The aneurysm was clipped and superficial temporal artery-DMCA anastomosis was performed. She was discharged with no neurologic deficits. Duplication of the middle cerebral artery can be divided into 2 types based on whether the site of separation from the ICA is at the top of the ICA (type A) or between the ICA top and the anterior choroidal artery (type B). The diameter of type A DMCA is comparable with that of the main middle cerebral artery trunk; in type B, it is smaller. In all 18 previously reported cases, the aneurysm was associated with type B DMCA.

Conclusion: For appropriate treatment planning, it is necessary to determine the DMCA type and the anatomic relationship between the aneurysm and the DMCA. In patients with type B DMCA, the possibility of aneurysm formation should be considered.