Hounsfield unit as a predictor of symptomatic vasospasm and hydrocephalus in good-grade subarachnoid hemorrhage treated with endovascular coiling

BACKGROUND: Patients with good-grade subarachnoid hemorrhage (SAH) often expect favorable outcomes; however, several patients may experience secondary neurological deterioration. Hydrocephalus and vasospasm are significant complications affecting SAH prognosis. We aimed to evaluate the relationship between the incidence of symptomatic vasospasm or hydrocephalus and the Hounsfield unit (HU) value of the subarachnoid space on brain computed tomography (CT) in patients with good-grade SAH treated with endovascular coiling. METHODS: We conducted a retrospective analysis of consecutive initially good-grade pure SAH patients (Hunt-Hess grade I or II, modified Fisher scale I or III) with ruptured anterior circulation aneurysms treated with endovascular coiling in a single tertiary neurosurgical center between January 2010 and December 2019. The HU value within each cisterns of enrolled patients was measured, and after setting an appropriate cutoff value, it was investigated whether it could be a predictor of the occurrence of vasospasm and hydrocephalus. RESULTS: The study included 108 eligible patients (34 males, mean age 60.88±12.26 years): 26 (24.1%) showed symptomatic vasospasm and 31 (28.7%) developed hydrocephalus. Patients with symptomatic vasospasm had a greater proportion of those with Hunt-Hess grade II (77% vs. 51%, P=0.021) and modified Fisher scale III scores (58% vs. 22%, P=0.001). The hydrocephalus group presented an older mean age (65.90 vs. 58.86 years, P=0.006) and a greater proportion of Hunt-Hess grade II (74% vs. 51%, P=0.025) and modified Fisher scale III cases (45% vs. 25%, P=0.037). The mean HU values of the Sylvian cistern (53.23 vs. 43.99, P<0.001) and basal cisterns (47.04 vs. 40.18, P=0.003) were higher in the vasospasm group. In the hydrocephalus group, only the basal cistern HU value was significantly higher (45.60 vs. 40.32, P=0.016). The area under the receiver operating characteristic (ROC) curve to determine the best cut-off HU value for the prediction of patients with symptomatic vasospasm revealed a Sylvian cistern HU value of 50.375 (sensitivity: 0.692, specificity: 0.683) and basal cistern HU value of 44.875 (sensitivity: 0.615, specificity: 0.659). Multivariable logistic analysis showed that age >70 years and Sylvian cistern HU value were independent predictors of any neurological complication at 1 year. CONCLUSIONS: The HU value of the subarachnoid space on brain CT can predict vasospasm, hydrocephalus, and long-term prognosis in good-grade SAH patients.