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

Abstract

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. To investigate whether splitting the inner hematoma membrane influences the recurrence rate in patients undergoing burr-hole craniotomy for CSDH. 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. Fourteen patients underwent reoperation for clinical deterioration or residual hematoma during follow-up (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%]). 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.