A Reliable Closure Technique for Retromastoid Craniotomy to Avoid Cerebrospinal Fluid Leaks and Meningitis.

Background and objectives: Postoperative cerebrospinal fluid (CSF) leaks and meningitis are well-known risks of retromastoid craniotomy. Use of abdominal fat grafts, collagen allografts, and rigid or semirigid buttresses have demonstrated efficacy in preventing CSF leaks and meningitis in endoscopic endonasal surgery. This study aims to determine the utility of a similar multilayered reconstruction technique for retromastoid craniotomy.

Methods: We retrospectively reviewed 212 consecutive patients who underwent retromastoid craniotomy for tumor removal or microvascular decompression from 2007 to 2022. Scalp incisions were linear or slightly curved, muscle and facia opening was performed sharply avoiding monopolar cautery; craniotomies had a maximum dimension of 3 cm. A primary water-tight dural closure was rarely achieved favoring collagen sponge overlay often augmented with autologous fat. Clinical factors including pathology, mastoid air cell entry, and reconstruction material were analyzed. Outcomes including postoperative CSF leakage and meningitis were assessed.

Results: Of 212 patients (mean age 56 ± 16 years; 60% female; 10% with prior surgery), 148 (70%) had tumor resection and 64 (30%) had microvascular decompression. Mastoid air cells were breached in 67%. Collagen sponge dural overlay was used in 201/212 (95%). A fat graft was placed in 116 (55%) cases: 69% with air cell entry, 27% without air cell entry; 158 (75%) patients had their bone flap replaced, 46 (21%) had titanium mesh cranioplasty, 8 (4%) had no bone flap or titanium mesh. There were no CSF leaks or meningitis. One patient had a lumbar drain placement preoperatively, none postoperatively. Median length of stay was 2 days.

Conclusion: Retromastoid craniotomy multilayered reconstruction with liberal use of collagen sponge and abdominal fat grafts seems to reliably avoid postoperative CSF leaks and meningitis including in the setting of nonwatertight dural closure and mastoid cell entry. Use of shorter incisions, avoidance of monopolar cautery, and a relatively small craniotomy may contribute to the absence of CSF leaks in this series.