Comparison of Bilateral and Unilateral Chronic Subdural Hematomas: A Multi-Institutional Review

Introduction: Chronic subdural hematoma (cSDH) is a major public health issue in the U.S. cSDH can present as unilateral or bilateral collections. We compared outcomes of surgically treated unilateral and bilateral cSDH and assessed factors contributing to retreatment.

Methods: We performed a retrospective chart review of patients operated for unilateral cSDH from four level 1 trauma centers, February 2009-August 2021. Patients were categorized into three groups: (1) unilateral, operated cSDH, (2) bilateral, operated cSDH on both sides, and (3) bilateral cSDH, but only one side operated. Patients with middle meningeal artery embolization were excluded. Data on demographics, clinical presentation, radiological findings, and outcomes were collected. A multivariable logistic regression model assessed factors associated with retreatment.

Results: We analyzed a total of 731 patients: 563 had unilateral operated cSDH; 132 had bilateral operated cSDH; and 36 had bilateral cSDH but were operated only on one side. We found no significant differences in retreatment rates between patients with bilateral, operated cSDH and those with unilateral, operated cSDH (14% vs. 12%, p = 0.40), 30-day readmission (30% vs. 25%, p = 0.20), or 30-day mortality (5.3% vs. 8.0%, p = 0.30). Increased postoperative volume was associated with a higher risk of retreatment (OR 3.24, 95% CI 2.15–5.07, p < 0.001). Patients with bilateral cSDH operated on one side showed no significant difference in retreatment (11% vs. 12%, p > 0.9), 30-day readmission (14% vs. 25%, p = 0.12), or 30-day mortality (5.3% vs. 8.0%, p > 0.9) compared to those with unilateral, operated cSDH.

Conclusion : There was no significant difference in retreatment, 30-day readmission, or 30-day mortality between unilateral and bilateral cSDH treated surgically. The laterality of cSDH was determined not to be a significant factor in predicting retreatment.