Application of zone classification in multiple intracranial aneurysmal subarachnoid hemorrhage treatment strategies

Background: The options of surgical approach and treatment stage are two challenging treatment strategy issues with multiple intracranial aneurysmal subarachnoid hemorrhage (MIA-SAH). Methods: We retrospectively analyzed data from patients with MIA-SAH who underwent surgery in our center between January 1, 2014 and September 1, 2022. To define "zone classification", the cranial cavity was divided into four zones by the planes of cerebral falx and tentorium cerebelli. Aneurysms isolated to one zone were defined as zone classification I; those crossing two zones were defined as zone classification II; those crossing three zones were defined as zone classification III; and those crossing four zones were defined as zone classification IV. General and aneurysmal-related characteristics of patients with different zone classifications were collected and compared between two surgical approaches. Multivariate logistic regression analysis was used to identify factors independently associated with multistage treatment options. Results: A total of 226 patients with 523 aneurysms were included. The proportion of patients undergoing endovascular treatment increased with higher zone classification (I: 85.4%; II: 94.0%; III: 100.0%; IV: 100.0%). The proportion of patients receiving one-stage treatment decreased with higher zone classification (I: 60.2%; II: 33.6%; III: 0.0%; IV: 0.0%). Compared with patients undergoing microsurgical clipping, more patients undergoing endovascular treatment had zone classification II-IV (56.9% vs. 31.8%, p = 0.025). Zone classification II-IV (odds ratio [OR] = 3.821, 95% confidence interval [CI]: 2.041-7.154, p < 0.001), endovascular treatment (OR = 8.756, 95% CI: 2.589-29.609, p < 0.001), and size of all unruptured aneurysms <3 mm (OR = 4.531, 95% CI: 2.315-8.871, p < 0.001) were each independently associated with multistage treatment. Conclusions: Zone classification provides a new idea in MIA-SAH treatment strategies, especially regarding surgical approach and treatment stage options.