A dynamic nomogram for predicting primary intraoperative brain bulge in patients with traumatic acute subdural hematoma

Abstract Purpose Intraoperative brain bulge (IOBB) is a serious and potentially life-threatening surgical complication. This study aimed to examine the predictive value of the hematoma thickness-to-midline shift (HT/MS) ratio and develop a new prediction model for primary IOBB in patients with traumatic acute subdural hematoma (tASDH). Methods This retrospective study included 140 patients who underwent surgical treatment for tASDH between January 2017 and November 2023. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors associated with primary IOBB. The predictive performance of the model was evaluated through receiver operating characteristic (ROC) curve analysis, calibration plots, and decision curve analysis. A dynamic nomogram for predicting primary IOBB was developed and made available online as an easy-to-use calculator. Results The incidence of primary IOBB in patients with tASDH was 17.86% (25/140). Bilateral pupillary dilation (odds ratio [OR] = 5.408), lower HT/MS ratio (OR = 0.170), and longer time from injury to surgery (OR = 4.612) were independent risk factors for primary IOBB. The basic model that included only traditional risk factors had an area under the ROC curve (AUC) of 0.721 (95% confidence interval [CI]: 0.603–0.840). Incorporating HT/MS ratio into the full model increased the AUC to 0.790 (95% CI: 0.679–0.901). Based on the full model, the nomogram was developed and exhibited satisfactory calibration performance. When the threshold probabilities ranged from 18% to 61%, the nomogram’s net benefit outperformed that of the basic model. Conclusions The HT/MS ratio is a novel predictor of primary IOBB in patients with tASDH. The developed dynamic nomogram is a valuable tool for predicting primary IOBB; however, further external validation is necessary.