Safety and Efficacy of Tiny (≤3 mm) Unruptured Middle Cerebral Artery Aneurysm Treatment: An Analysis of the NeuroVascular Quality Initiative-Quality Outcomes Database Cerebral Aneurysm Registry

BACKGROUND AND OBJECTIVES: Improved imaging modalities have led to an increased detection of intracranial aneurysms, many of which are small. There is uncertainty in the appropriate management of tiny aneurysms. The objective of this study was to use a large, multi-institutional NeuroVascular Quality Initiative-Quality Outcomes Database (NVQI-QOD) to assess the frequency, safety, and efficacy of treatment of tiny, unruptured middle cerebral artery (MCA) aneurysms. METHODS: The NeuroVascular Quality Initiative-Quality Outcomes Database registry was queried for patients with tiny unruptured MCA aneurysms who underwent treatment. Tiny size was defined as an aneurysm with a maximum dimension of ≤3 mm. Demographics, aneurysm characteristics, and treatment safety were queried. Outcomes included modified Rankin Score (mRS) at discharge and the last follow-up as well as aneurysm occlusion status at discharge. RESULTS: Of 674 treated, unruptured MCA aneurysms, 57 (8.5%) were tiny. The mean aneurysm width was 2.2 mm, and the mean patient age was 55.9 years. Most aneurysms were treated with microsurgery (61.4%, 35/57). The overall intraoperative complication rate was 5.3% (3/57), and the postoperative complication rate was 10.5% (6/57). 10.5% (6/57) of patients were discharged to rehabilitation. At discharge, 42 (87.5%) of the treated aneurysms had complete occlusion. In the subgroup of patients with recorded follow-up data, 48.3% (14/29) had a mRS of 0 at discharge and 46.9% (15/32) had an mRS of 0 at the last follow-up (median follow-up 166 days). CONCLUSION: Treatment of tiny, unruptured MCA aneurysms is efficacious but may have a high rate of complications. Physicians should be cautious when deciding to treat tiny, unruptured MCA aneurysms.