Opening the Internal Hematoma Membrane does not Alter the Recurrence Rate of Chronic Subdural Hematomas - A Prospective Randomized Trial

Abstract Background Factors determining the recurrence of chronic subdural hematomas (CSDH) 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 the inner hematoma membrane (group A) or not (group B) after enlarged burr-hole craniotomy and hematoma evacuation. A drainage was left in situ for several days postoperatively. Groups were comparable with regard to demographic, clinical and imaging variables. Outcome was assessed after three to six weeks for the combined outcome variable of reoperation and/or residual hematoma of ≥ 1/3 of the original hematoma thickness. Results Fourteen patients underwent reoperation for clinical deterioration and/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 n=7 patients of group A (25%) and n=10 patients of group B (36%) (P=0.383). The overall cumulative failure rate (reoperation and/or hematoma thickness ≥1/3) was 13/28 (46%) in group A and 18/28 in group B [P=0.178, RR 0.722 (95%CI 0.445 to 1.172), ARR -16% (95%CI -38% to 8%)]. Conclusion 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 six weeks after evacuation of a CSDH.