Predictors of early functional outcome after microsurgical clipping of ruptured intracranial aneurysms: A retrospective series focusing on ventricular system variables

Early functional status after aneurysmal subarachnoid hemorrhage (aSAH) reflects the interaction of admission severity, hemorrhage burden, ventricular involvement, and systemic complications. This study examined clinical, radiological, ventricular-system, and metabolic factors associated with early outcome in patients who underwent microsurgical clipping for ruptured intracranial aneurysms. We retrospectively reviewed 43 adult patients treated with surgical clipping between January 2022 and April 2026. Functional outcome was graded with the Glasgow Outcome Score (GOS) at the first-month follow-up after discharge or, for patients who died before follow-up, according to the last available in-hospital outcome status. Outcomes were classified as favorable for GOS 4-5 and unfavorable for GOS 1-3, with GOS 1 representing death. Ventricular-system involvement was evaluated using continuous Evans index values, the Evans index ≥ 0.30 threshold, intraventricular hemorrhage (IVH), external ventricular drainage (EVD) requirement, and shunt requirement. Twenty-six patients (60.5%) had a favorable outcome, while 17 patients (39.5%) had an unfavorable outcome. WFNS score and Fisher grade were higher in the unfavorable outcome group. EVD requirement, rebleeding, metabolic disturbance, and intracerebral hematoma were also associated with unfavorable outcome. Continuous Evans index values were not significant; however, the Evans index ≥ 0.30 threshold was associated with unfavorable outcome, EVD requirement, and shunt requirement. Of seven patients treated with EVD, only one later required shunt placement, whereas five had GOS 1/death. Early unfavorable outcome after aSAH appears to result from the combined influence of admission severity, hemorrhage burden, acute CSF diversion need, rebleeding, intracerebral hematoma, and metabolic deterioration rather than a single radiological measure. Evans index ≥ 0.30 may be a clinically meaningful threshold for ventricular enlargement.