MATERIAL and METHODS: We conducted a retrospective analysis on 125 patients who underwent 138 surgical interventions for MCA aneurysms and were treated with microsurgical clipping and endovascular embolization at the Department of Neurosurgery in the University Hospital ?St. Iv. Rilski?, Sofia, in 2013?2019. In six of these cases, we observed mirror MCA aneurysms.

RESULTS: All six patients with ?mirror? aneurysms were female. In one case, a third aneurysm was observed on the anterior communicating artery; hence, a total of 13 aneurysms were treated. The average age of the group was 48.16 years. All patients had known risk factors, such as high blood pressure and tobacco smoking. Four patients presented with aneurysmal subarachnoid hemorrhage (aSAH). All patients underwent surgical treatment in two stages?with obliteration of the intracranial aneurysm leading to subarachnoid bleeding in the first stage and planned surgical intervention within a month in the second stage to exclude unruptured aneurysms. During the one-month interval, there were no SAH incidents. However, we observed one patient with a postoperative neurological deficit and one with recanalization of the aneurysm on follow-up at 3 months, requiring re-embolization. In both cases, endovascular treatment was performed despite the unfavorable anatomical features (aspect ratio ?1.5 and neck size ?4 mm). The clinical outcome, in all operated patients, for ?mirror? aneurysms of the MCA was reasonable (mRS: 0-2).

CONCLUSION: The choice of treatment for ?mirror? aneurysms should be determined on an individual basis by the clinical manifestations and morphological characteristics of intracranial aneurysms. In cases of aSAH, where ?mirror? aneurysms are present, both can be treated safely via microsurgical clipping or endovascular embolization after thorough investigation and ensuring prioritization of the offending lesion. Keywords : MCA aneurysms, Mirror aneurysms, Microsurgical clipping, Endovascular procedures, Geometrical features