Systemic Immune-Inflammation Index and Clinical Predictors of Atypical PRES in Eclampsia: Higher Blood Pressure and...

Objective: To identify clinical and neuroimaging predictors of atypical Posterior Reversible Encephalopathy Syndrome (PRES) in eclampsia and evaluate the role of multi-regional cerebral involvement (neuroimaging burden). Methods: This retrospective cohort study included 266 patients with eclampsia and radiologically confirmed PRES (2018-2025). Patients were classified as typical (n = 234, 88.0%) or atypical (n = 32, 12.0%). A two-stage multivariable logistic regression was performed to identify independent predictors, sequentially incorporating clinical and neuroimaging variables. Results: Peak systolic blood pressure was significantly higher in atypical vs. typical groups (191.6 ± 20.4 vs. 172.4 ± 18.5 mmHg, p < 0.001). Furthermore, atypical cases exhibited a significantly higher systemic inflammatory burden, characterized by markedly elevated Systemic Immune-Inflammation Index (SII) and CRP levels (p < 0.001). Atypical cases exhibited a markedly greater neuroimaging burden, with a higher mean number of involved brain regions (4.4 ± 1.2 vs. 2.1 ± 0.6, p < 0.001). In Model 1 (clinical variables only), systolic blood pressure was a strong predictor of atypicality (OR: 1.24 per 10 mmHg increase, 95% CI: 1.12-1.38, p < 0.001). After incorporating neuroimaging features in Model 2, the total number of involved brain regions emerged as the strongest independent predictor (OR: 2.08, 95% CI: 1.52-2.85, p < 0.001), while the independent effect of blood pressure was attenuated. Conclusions: Atypical PRES in eclampsia reflects extensive, high-burden cerebral vasogenic edema rather than a distinct radiological subtype. While hypertension initiates the process, the total regional burden determines the atypical signature. This burden-focused perspective improves risk stratification and diagnostic vigilance in high-risk obstetrics.