336 Resolution of Treated Chronic Subdural Hematomas

INTRODUCTION: Chronic subdural hematomas (CSDH) are common with increasing incidence. Multiple treatment modalities are available, with recent studies supporting middle meningeal artery embolization (MMAE). However, all treatment methods leave residual fluid which resorbs over time. The time course of subdural fluid resolution is not well characterized but can persist for months. METHODS: A retrospective review of subdural hematomas surgically treated at our institution from 2015-2017 yielded 90 chronic subdural hematomas meeting the criteria. Time to Resolution was determined by stabilization of decreasing SDH thickness by radiographic and physician records, and investigator review of the CT scans. Kaplan-Meier curves assessed the time to resolution of CSDH. RESULTS: 90 individual CSDH were treated with 55 burrholes, 31 craniotomies, 2 twist drills and 2 subdural evacuating ports. Follow-up times were highly variable (1-445 weeks), with 16 cases having >60-week follow-up (all resolved). Median CTs obtained was 4 (IQR 3-5). There were 7 CSDHs with 0 or 1 follow-up CT. Using the entire cohort, a median time to resolution was 13 weeks (IQR 6-38.5). When excluding outliers (>60 weeks), the median time to resolution was 11 weeks. The median time to resolution was 11 and 10 weeks for craniotomies and burrholes, respectively (p=0.30, Hazard Ratio 1.33, CI 0.77-2.31). CONCLUSIONS: In a pre-MMAE cohort, follow-up was highly variable. However, when evaluating those cases where follow-up was <1 year, the median time to resolution was 11 weeks and did not differ between operative modalities. This study standardizes the pre-MMAE follow-up and resolution times for comparison with MMAE, which does not immediately reduce mass effect, and for which standardized follow-up times remain to be determined.