Endovascular treatment of small (< 5 mm) unruptured middle cerebral artery aneurysms

Purpose: We report our experience with endovascular treatment of these lesions, with special consideration of angiographic and clinical outcomes and periprocedural complications. Material and methods: The analysis included treatment results of 19 patients with 20 aneurysms. The aneurysm size ranged from 1.9 to 4.7 mm (mean 3.8, SD 0.7). Clinical examinations with the use of modified Rankin Score and angiographic outcomes were evaluated initially postembolisation and at a minimum follow-up of six months. Results: Initial post-treatment complete and near-complete aneurysm occlusion was achieved in 19 (95%) cases and incomplete occlusion in one (5%) case. Imaging follow-up, performed in 17 (89.4%) patients, showed no change in the degree of occlusion in 16 (94.1%) patients and coil compaction in one (5.9%). There were no retreatment procedures. The procedure-related mortality rate was 5% (1/20) and was associated with intraprocedural aneurysm rupture. There was a case of a clinically silent coil prolapse into the parent artery. The clinical follow-up evaluation achieved in 17 (89.4%) patients showed no change in clinical status in all followed patients. Conclusions: Endovascular treatment of small unruptured middle cerebral artery aneurysms is feasible and effective. The procedure-related complications are not negligible, especially in terms of the benign natural course of these lesions.