Analysis of Endoscopic Findings in the Chronic Subdural Hematoma Cavity: Bleeding Factors in Chronic Subdural Hematoma Natural History and as Predictors of Recurrence

Possible factors associated with bleeding from endoscopy-detected chronic subdural hematomas (CSDHs) have rarely been analyzed. We therefore evaluated intraoperative endoscopic findings to elucidate the clinical course and assess predictors of CSDH recurrence. Altogether, 540 CSDHs were reviewed in this retrospective study. Six possible signs of bleeding were detected in the cavity: spotty bleeding on the outer membrane, hematoma clots, cerebral parenchymal suspension, stretched cortical vessels, intraluminal trabecular structures, and septa separating the cavity. We evaluated the association of each with the radiologic findings, endoscopic features, and interval from trauma to surgery and then assessed the correlation between each endoscopic feature and CSDH recurrence. Spotty bleeding, cerebral parenchymal suspension, and stretched cortical vessels occurred during every period. Hematoma clots exhibited a 2-peak pattern with significant resurgence during the chronic phase. Trabecular structures significantly increased 61 days after the trauma, reaching 71.2% of patients on day 91. Septa were found in the cavity in only 12.5% during the initial 30 days but subsequently increased significantly to 37.3%. At 2 months, an exacerbation stage was inferred. The multivariable analysis revealed that trabecular structures and residual septa were significant independent risk factors for recurrence. We opened most septa intraoperatively. Their recurrence rate was 7.5%, which is lower than has been previously reported. Evaluation of the changes in the endoscopic findings and their association with recurrence was useful for clarifying the mechanism of CSDH enlargement, the risk of recurrence, and the potential for endoscopic surgery.