2025 Proffered Presentations
S090: INCIDENCE OF CEREBROSPINAL FLUID (CSF) RHINORRHEA AFTER POSTERIOR WALL DURA REPAIR OF THE INTERNAL AUDITORY CANAL WITH COLLAGEN MATRIX IN RETROSIGMOID VESTIBULAR SCHWANNOMA RESECTION
Osamu Akiyama, PhD1; Yuzaburo Shimizu, PhD1; Mario Suzuki, PhD1; Ryo Miyahara1; Takuma Kodama1; Noritaka Komune, PhD2; Satoshi Matsuo, PhD3; Akihide Kondo, PhD1; 1Department of Neurosurgery, Juntendo University Faculty of Medicine, Tokyo, Japan; 2Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.; 3Department of Neurosurgery, Fukuoka Tokushukai Hospital, Fukuoka, Japan
BACKGROUND: Gross total removal of vestibular schwannomas requires adequate exposure of the internal auditory canal (IAC), typically achieved using the retrosigmoid approach. However, drilling the posterior wall of the IAC exposes the petrous air cells, risking cerebrospinal fluid (CSF) rhinorrhea. Prevention of CSF rhinorrhea from the posterior wall of the IAC is commonly achieved by closing open petrous air cells with autografts such as muscle or fat. Biodegradable collagen matrices (BCM) offer a safe and secure alternative, functioning as scaffolds for dural tissue regrowth without requiring sutures. In recent years, we have used bone wax and BCM instead of traditional autologous tissue to close petrous air cells.
Here, we describe our experience in closing petrous air cells adjacent to the posterior wall of the IAC using the BCM and report the incidence of CSF rhinorrhea.
METHODS: We retrospectively reviewed 101 consecutive cases of vestibular schwannoma treated with the retrosigmoid approach and BCM to repair the posterior IAC wall, from January 2022 to April 2024. After excluding recurrent cases, 87 cases were analyzed for the incidence of postoperative CSF leakage and patient background details (age, sex, and tumor size).
The closure of the petrous air cells and repair of the dura mater of the posterior IAC wall were performed as follows: First, exposed air cells in the petrous bone were filled with bone wax. The incised posterior wall dura of the internal auditory canal was then positioned over the exposed air cells. The BCM, cut to appropriate size, was placed over the dura, followed by a slightly larger BCM. Finally, fibrin glue was sprayed over BCM to secure it in place.
RESULTS: Among the 87 patients (41 males, 46 females; mean age 57.1 years), 42 tumors were left-sided and 45 were right-sided. The Koos classification of the tumors was as follows: I in one case, II in 12 cases, III in 26 cases, and IV in 48 cases. Postoperative computed tomography (CT) evaluation revealed open petrous air cells in the posterior wall of the IAC in 51 of the 87 cases. CSF rhinorrhea occurred in two patients: one was managed with lumbar drainage, and the other required surgical intervention for CSF leak closure. No additional complications were observed during the mean observation period of 18.8 months.
CONCLUSIONS: Collagen matrices allow safe and effective closure of exposed air cells in the IAC following vestibular schwannoma removal. BCM have the potential to become the next-generation sealant for petrous air cell closure. Dural closure of the posterior wall of the IAC using BCM proved to be a safe surgical technique with a low incidence of CSF rhinorrhea.