MISIAN (Minimally Invasive Surgery for Treatment of Unruptured Intracranial Aneurysms): A Prospective Randomized Single-Center Clinical Trial With Long-Term Follow-Up Comparing Different Minimally Invasive Surgery Techniques with Standard Open Surgery.

Background: Unruptured intracranial aneurysms (UIAs) are increasingly diagnosed but treatment is still controversial. Although the descriptions and use of minimally invasive surgery (MIS) have increased, comparative studies with standard approaches are rare.

Objective: MISIAN (Minimally Invasive Surgery for Treatment of Unruptured Intracranial Aneurysms) is a prospective randomized single-center clinical trial with long-term follow-up comparing different MIS techniques with standard open surgery for treatment of UIAs.

Methods: We randomly allocated a standard pterional approach (PtA) or MIS (1:2) to 111 patients with UIAs of the anterior circulation (mean dome diameter, 6.4 mm; range, 3-20 mm). Patients selected for MIS underwent a second randomization between a transeyelid approach (TelA) or nanopterional approach (NPtA) (1:1).

Results: Forty-one patients were randomized to and treated with the PtA, 36 with the TelA, and 34 with the NPtA. Only patients treated with PtA had permanent facial nerve palsy (n = 4 [10%]; P = 0.032). MIS cosmetic results were considered better than those of PtA by independent observers (P < 0.001), and less temporal atrophy in the MIS group was also observed (P = 0.0034). The proportion of excellent results was higher in the TelA group than in the NPtA group (86% vs. 67.6%; P = 0.039). Patients undergoing MIS also reported consistently higher satisfaction and quality-of-life scores (P < 0.001).

Conclusions: MIS is superior to standard PtA for microsurgical clipping of small UIAs of the anterior circulation in terms of cosmetic, satisfaction, and quality-of-life outcomes. The TelA or NPtA for UIAs did not show significant outcome differences at 12-18 months.