Quantitative pupillometry in predicting delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis.

Delayed cerebral ischemia (DCI) is the main cause of secondary neurological deterioration after aneurysmal subarachnoid hemorrhage (aSAH). Conventional monitoring lacks predictive accuracy, especially in sedated or comatose patients. Quantitative pupillometry provides an objective assessment of pupillary light reflexes and may facilitate early detection of DCI. A systematic review and meta-analysis were conducted in accordance with the PRISMA 2020 guidelines (PROSPERO: CRD420251132144). PubMed, Embase, and Web of Science were searched through August 2025 for studies evaluating automated pupillometry in adults with aSAH. Eligible studies analyzed associations between pupillometry metrics and DCI or clinical outcomes. Data were synthesized narratively, and pooled estimates were calculated using a random-effects model. Abnormal pupillometry, typically defined as a Neurological Pupil index (NPi) < 3, was significantly associated with DCI, mortality, and poor outcomes. Two studies (n = 266) were included in meta-analysis, showing that abnormal NPi was associated with increased odds of DCI (pooled OR 2.15; 95% CI 1.25–3.71; I² = 0%). Pupillary alterations frequently preceded clinical deterioration by several hours. Pooled diagnostic performance showed a sensitivity of 47.2%, specificity of 70.6%, positive predictive value of 53.3%, and negative predictive value of 65.4%. Quantitative pupillometry may represent a non-invasive adjunct for DCI risk stratification after aSAH, though its limited diagnostic performance warrants cautious interpretation and further validation.