Abstract Number: Esoc2026a974 Incidence, Features and Impact of Non-Convulsive Status Epilepticus in Aneurysm Subarachnoid Haemorrhage: A Single Centre Prospective Study

Abstract Background and aims Complications after aneurysmal subarachnoid hemorrhage (aSAH) remain only partially understood. This study aimed to identify predictors of seizures and to explore their association with EBI, DCI, and mortality. Methods We retrospectively analyzed patients with aSAH admitted to the ICU of Bufalini Hospital between 2019 and 2025. Demographic, clinical, EEG, and radiological variables were collected. Univariable and multivariable logistic regression analyses were conducted to identify independent predictors of seizures, while secondary analyses explored factors associated with EBI, DCI, and mortality. Results Among 195 included patients, NCSE or overall seizures occurred in 12.8%. Patients with seizures had longer ICU stays (20.0 ± 11.0 vs 10.8 ± 8.7 days, p0.001), more hydrocephalus (75.0% vs 40.4%, p=0.001), higher rates of DVE (89.3% vs 55.4%, p=0.001), and more vasospasm (57.1% vs 26.5%, p=0.002). In multivariable analysis, vasospasm remained the only independent predictor (OR 3.30, 95% CI 1.15–9.72, p=0.028). EBI was associated with higher Hunt–Hess and modified Fisher scores, early complications (rebleeding, fever, hyponatremia), and moderate vasospasm, whereas DCI correlated with hypertension, CTA/TCD vasospasm, perfusion deficits, and clinical deterioration. Mortality was linked to baseline severity (WFNS, IVH, raised ICP) but not to seizure occurrence. Conclusions Vasospasm emerged as the main determinant of overall seizures after aSAH, suggesting that vasospasm should not only be treated to prevent DCI but also recognized as a marker of cortical excitability and potential ictogenesis. Multimodal monitoring integrating cEEG, TCD, CTA/CTP, and ICP measurements may help detect and interrupt the vicious cycle between hypoperfusion and seizure activity. Conflict of interest Claudia Faini: nothing to disclose; Carlo Bergamini: nothing to disclose; Andrea Salcuni: nothing to disclose; Luca Bastia; nothing to disclose; Mattia Carnelli: nothing to disclose; Manlio Meca; nothing to disclose; Luca Gobbi: nothing to disclose; Francesca Gatti: nothing to disclose; Elvis Lafe: nothing to disclose; Marcello D'Andrea: nothing to disclose; Marco Longoni; nothing to disclose; Vanni Agnoletti: nothing to disclose; Luigino Tosatto: nothing to disclose; Maria Ruggiero: nothing to disclose; Yerma Bartolini: nothing to disclose; Michele Romoli: nothing to disclose.