Natural history and clinical outcomes in patients with complex intracranial aneurysms: a review of 115 bypass cases and 22 nonsurgical cases.

The purpose of this study was to evaluate the natural history of patients with these heterogeneous aneurysms to provide guidance for their treatment. This retrospective analysis was performed at a single institution and included 137 patients with complex intracranial aneurysms who underwent a natural history evaluation. Among the 115 patients who underwent bypass surgery, stroke (n = 39, 33.9%) was the most common clinical symptom followed by progressively severe headaches (n = 25, 21.7%). Of the 104 patients with follow-up information, 87 (83.7%) returned to a normal life within a mean follow-up of 4.17 ± 2.09 years. Ten deaths (9.6%) occurred after a mean of 1.3 ± 0.9 years. Among the 22 patients who selected nonsurgical treatment, mass effect (n = 9, 40.9%) was the most common clinical presentation, and 14 deaths (63.6%) occurred after a mean of 3.3 ± 2.5 years. The modified Rankin scale (mRS) scores of 5 survivors (5/22, 22.7%) progressed from 0-2 at initial presentation to 3-4. Bypass surgical treatment for these aneurysms appears to be effective and can achieve good clinical outcomes without additional limitations related to individual aneurysms despite the impact of recent endovascular techniques on vascular surgery.