The diagnosis of infections associated with acrylic cranioplasties.

Fifty-two methylmethacrylate cranioplasties were performed on forty-seven patients over a five year period. Two cranioplasties became infected and required removal. The overall infection rate for methylmethacrylate cranioplasty was thus 2/52 or 3.8%. Both of these patients had bifrontal cranioplasties involving both orbital rims and the frontal sinus. The infection rate for those cranioplasties involving the frontal sinus was 2 of 9 or 22%. None of the 43 cranioplasties not involving the frontal sinus became infected. Ten patients in this series had postoperative CT scans. Gas within the non-infected methylmethacrylate could simulate infection, making it difficult to diagnose cranioplasty infections by CT. Although certain CT changes, such as epidural air and soft tissue swelling, may be observed only with infected cranioplasties, the clinical picture is the only truly reliable indicator of infection.