Double-layer appearance after evacuation of a chronic subdural hematoma

Objective. To investigate the reason for and the course of the double-layer appearance in the postoperative computed tomographies (CTs) of chronic subdural hematoma (CSDHs). Methods. We reviewed CSDH cases that were operated on during the last 3 years, between January 2008 and December 2010. We checked the preoperative, early postoperative, and late postoperative CTs of these patients. We investigated the relationship between the formation of a double-layer appearance and the prognoses and demographic characteristics of the patients. Results. Our database included 119 cases. A double-layer appearance was found in the postoperative CTs of 34 cases. The mean age of double-layer cases was older (72.5 +/- 12.1) than that of the remaining 85 cases (63.1 +/- 17.8). We did not find any relationship between the double-layer appearance and the reoperation/recurrence/death rates. Conclusions. The double-layer appearance after evacuation of a CSDH might be caused by enlargement of the subarachnoid space and is not related to the presence of any residual hematoma. This appearance is not considered as a reason for reoperation.