Critical Depressed Brain Volume Influences the Recurrence of Chronic Subdural Hematoma after Surgical Evacuation.

Recurrence of chronic subdural hematoma (CSDH) frequently occurs after surgical evacuation. However, the value of follow-up postoperative imaging and measuring volumetric factors to predict recurrence are still controversial. Herein, we aimed to assess the optimal timing for follow-up referential imaging and the critical depressed brain volume for CSDH recurrence. A total of 291 patients with CSDH who underwent burr hole craniotomy between January 2012 and December 2018 were consecutively enrolled in this study. Patients' medical records and radiologic data were evaluated to predict the recurrence and analyzed using receiver operating characteristics (ROC) and binary logistic regression. Of the 291 patients, 29 (10.0%) showed recurrence after surgical evacuation. Based on ROC analysis, comparisons of depressed brain volume pre-operation, 24 h post-operation, and 7 days post-operation showed that the depressed brain volume at 7 days after surgery featured the largest area under the curve (AUC: 0.768, 95% CI, 0.709-0.811). The cut-off value of the depressed brain volume on postoperative day 7 was 51.6 cm; this value predicted the recurrence of CSDH with a sensitivity and specificity of 79.3% and 67.9%, respectively. In the multivariate analysis, the depressed brain volume (>50 cm) at 7 days was the sole significant risk factor related to the recurrence of CSDH in this series (OR: 6.765, 95% CI, 2.551-17.942, p < 0.001). The depressed brain volume > 50 cm visualized on CT scans at postoperative 7 day is the critical volume affecting recurrence of CSDHs. This result could be helpful carrying in patients with CSDH to determine the proper postoperative treatment strategy.