Risk Factors for Contralateral Hematoma Progression after Unilateral Evacuation of Bilateral Chronic Subdural Hematomas

To find risk factors for contralateral hematoma progression (CHP) in bilateral chronic subdural hematomas after initial unilateral evacuation.We retrospectively analyzed 53 patients with bilateral chronic subdural hematomas who underwent unilateral surgical evacuation in our department. Risk factors for CHP were identified by univariate analysis, a P value <0.05 were entered into multivariate logistic regression model and a predictive receiver operating characteristic curve model.The progression rate was 32.08%, the average progression interval was 2.32 months. The progression rate of the homogeneous hypodense group was significantly higher than that of the other density group (P = 0.017). The limited type of contralateral hematoma had a significantly lower progression rate than that of the widespread type (P = 0.001). Both pre- and postoperative volume of contralateral hematoma were significantly more in the CHP group compared with the contralateral hematoma without progression group (P = 0.031 and P = 0.001, respectively). Of the 4 risk factors, only postoperative volume of contralateral hematoma was an independent risk factor in multivariate logistic regression model (P = 0.033; 95% confidence interval, 1.005-1.124). The cut-off values of contralateral hematoma volume before and after operation were 29.27 cm3 and 37.84 cm3, respectively.Contralateral hematoma volume after operation is an independent risk predictor for CHP after unilateral evacuation. An additional surgery on contralateral hematoma or medical treatment should be taken into consideration if the volume is >37.84 cm3 in the first cranial computed tomography scan after surgery.