Opening the Internal Hematoma Membrane Does Not Alter the Recurrence Rate of Chronic Subdural Hematomas: A Prospective Randomized Trial

BACKGROUND: Factors determining the recurrence of chronic subdural hematomas (CSDHs) are not clear. Whether opening the so-called internal hematoma membrane is useful has not been investigated. OBJECTIVE: To investigate whether splitting the inner hematoma membrane influences the recurrence rate in patients undergoing burr-hole craniotomy for CSDH. METHODS: Fifty-two awake patients undergoing surgery for 57 CSDHs were prospectively randomized to either partial opening of the inner hematoma membrane (group A) or not (group B) after enlarged burr-hole craniotomy and hematoma evacuation. Drainage was left in situ for several days postoperatively. Groups were comparable with regard to demographic, clinical, and imaging variables. Outcome was assessed after 3-6 weeks for the combined outcome variable of reoperation or residual hematoma of one third or more of the original hematoma thickness. RESULTS: Fourteen patients underwent reoperation for clinical deterioration or residual hematoma during followup (n = 6 in group A, 21%; n = 8 in group B, 28 %) (P= 0.537). Residual hematoma of >= one third not requiring surgery was present in 7 patients in group A (25%) and 10 patients in group B (36%) (P = 0.383). The overall cumulative failure rate (reoperation or hematoma thickness >= one third) was 13/28 (46%) in group A and 18/28 in group B (P = 0.178; relative risk, 0.722 = 95% confidence interval, 0.445-1.172]; absolute risk reduction -16% = 95% confidence interval, -38% to 8%]). CONCLUSIONS: Opening the internal hematoma membrane does not alter the rate of patients requiring revision surgery and the number of patients showing a marked residual hematoma 6 weeks after evacuation of a CSDH.