Comparative performance of 4 image scoring systems for vasospasm prediction after aneurysmal subarachnoid hemorrhage: superiority of the modified Hijdra total score

OBJECTIVE: The Fisher scale remains the most widely used CT-based grading system for predicting vasospasm following aneurysmal subarachnoid hemorrhage (aSAH), despite its recognized limitations. Alternative scoring systems, including the modified Fisher scale and quantitative blood burden assessment methods (Hijdra sum score and modified Hijdra total score), lack systematic comparative validation. In this study, authors compared the predictive performance of 4 CT-based image scoring systems for vasospasm occurrence in patients with aSAH. METHODS: This retrospective study included consecutive patients with aSAH who were admitted to a single institution between January 2020 and June 2025. Initial noncontrast CT scans were independently assessed by neurosurgeons and reviewed by neuroradiologists using the Fisher scale, modified Fisher scale, Hijdra sum score, and modified Hijdra total score. Vasospasm was classified into 3 categories (none, asymptomatic, and symptomatic) using daily transcranial Doppler ultrasonography monitoring (days 3-14), with CTA and CT perfusion imaging for patients with poor acoustic windows. Ordinal logistic regression was performed to quantify associations between imaging scores and vasospasm severity. RESULTS: Among the 370 patients included in the study (mean age 59.9 ± 13.6 years, 65.7% female), 228 (61.6%) developed vasospasm (182 symptomatic, 46 asymptomatic). The modified Hijdra total score demonstrated the greatest area under the receiver operating characteristic curve (AUROC) for any vasospasm (0.802, 95% CI 0.751-0.849), followed by the Hijdra sum score (0.759, 95% CI 0.709-0.809), modified Fisher scale (0.663, 95% CI 0.618-0.710), and Fisher scale (0.597, 95% CI 0.551-0.643). At a cutoff of ≥ 28 points, the modified Hijdra total score demonstrated 84.6% sensitivity and 67.6% specificity. The modified Hijdra total score explained the greatest variance in vasospasm severity (Nagelkerke R2 = 0.239; OR 1.103 per point, 95% CI 1.083-1.127, p < 0.001). Fisher-based scales demonstrated ceiling effects, with 77% of patients classified as having grade 4 SAH. The modified Hijdra total score, which excludes ventricular compartments, outperformed the original Hijdra sum score (ΔAUROC = -0.043, p = 0.024). CONCLUSIONS: The modified Hijdra total score outperformed Fisher-based categorical scales in vasospasm prediction in this cohort. Quantitative cisternal blood assessment provided superior discrimination compared to categorical grading, with an optimal threshold of ≥ 28 points. The superior performance of the modified Hijdra total score, which excludes ventricular blood, suggests that cisternal blood burden is the primary driver of vasospasm risk. Prospective validation in independent cohorts is needed.