Dissecting aneurysm in poor-grade subarachnoid hemorrhage

OBJECTIVE Intracranial dissecting aneurysms (DAs) are rare and challenging lesions, often associated with high rates of rebleeding and poor clinical outcomes. There is limited evidence regarding optimal treatment strategies, timing, and outcomes, especially in the context of poor-grade subarachnoid hemorrhage (pSAH). The authors aimed to describe the clinical features and treatment outcomes of patients with DAs included in a national multicentric registry of pSAH and to identify independent outcome predictors within this subpopulation. METHODS The authors conducted a retrospective analysis of prospectively collected data from the multicenter Poor-Grade Aneurysmal Subarachnoid Hemorrhage (POGASH) registry, including consecutive patients admitted between January 1, 2015, and June 30, 2024. Poor grade was defined as a pretreatment World Federation of Neurosurgical Societies grade IV–V. Outcomes were assessed using the modified Rankin Scale. DAs were classified according to the Mizutani classification. RESULTS Of the 693 consecutive pSAH patients included in the registry, data from 60 patients with DA were analyzed. Among the 54 treated patients, 88.9% underwent endovascular treatment (vessel occlusion [48%], flow diversion [26%], and coiling [26%]), while 11.1% were treated surgically. The median (IQR) time to treatment was 6 (4–9) hours from symptom onset. Rebleeding occurred in 23.3% of patients, significantly more frequently than in the overall cohort (p < 0.048). Rebleeding independently predicted in-hospital mortality (adjusted OR 7.4; 95% CI 1.5–35.1; p = 0.011) and long-term disability (adjusted OR 0.08; 95% CI 0.007–0.98; p = 0.04). Internal carotid artery blister aneurysms were independently associated with rebleeding (adjusted OR 8; 95% CI 1.2–50; p = 0.027). CONCLUSIONS In the context of pSAH, DAs are characterized by distinct clinicoradiological features and carry a significant risk of ultra-early rebleeding, which strongly influences clinical outcome. These findings suggest a potential benefit of ultra-early or immediate treatment in this patient population, pending further validation.