2025 Poster Presentations
P107: THE OPERATION OF LOWER CRANIAL NERVE TUMORS IN OUR DEPARTMENT
Ryokichi Yagi, MD, PhD; Hideki Kashiwagi, MD, PhD; Kouhei Yoshimura, MD, PhD; Masao Fukumura, MD, PhD; Yuichirou Tsuji, MD, PhD; Gen Futamura, MD, PhD; Ryo Hiramatsu, MD, PhD; Masahiro Kameda, MD, PhD; Naosuke Nonoguchi, MD, PhD; Motomasa Furuse, MD, PhD; Shinji Kawabata, MD, PhD; Toshihiro Takami, MD, PhD; Masahiko Wanibuchi, MD, PhD; Osaka Medical and Pharmaceutical University
Introduction: Lower cranial nerve tumors are rarely encountered tumors that originate from the inferior cranial nerves. Although radiotherapy has been widely reported as a treatment for these tumors, surgical removal of the entire tumor is curative. However, total resection is sometimes difficult due to the anatomical location and nature of the tumor. We report on the surgical techniques and results of treatment of schwannomas of the inferior cerebral nerve at our institution.
Subjects and Methods: Nine cases of lower cranial nerve schwannomas that underwent craniotomy at our hospital over a 4-year period from February 2020 to June 2024 were included. The primary sites of origin were the glossopharyngeal nerve, vagus nerve, hypoglossal nerve, and glomus tumor in one case, two cases, five cases, and one case, respectively. The skin incision was made in the L-shape with the sternocleidomastoid muscle anteriorly and the cephalothoracic plate muscle and deeper layers were dissected and transversed posteriorly. The craniotomy is performed using a cutting bar to remove bone, and an additional craniotomy is performed using Ruel and other techniques. In sublingual schwannomas, the occipital condyle is removed and the sublingual neural tube is freed. The bicipital and lateral cranial rectus muscles are identified and cauterized to secure the external view. In cases with dumbbell-shaped extracranial extension, the entire sublingual nerve canal is removed until it is obvious. In addition, nerve bundles other than the causative nerve are preserved as much as possible.
Results: Four of the nine cases were totally resected, three cases had residual capsules, and two cases had partial tumor residuals. After surgery, there were no obvious neurological deficits other than hypoglossal neuropathy.
Conclusion: We reviewed the surgical treatment of schwannomas of the lower cranial nerves at our hospital. Since the number of cases is small and the follow-up period is short, we would like to accumulate more cases in the future and study the long-term results of treatment.