2025 Poster Presentations
P179: MANIPULATION OF LOWER CRANIAL NERVES AND JUGULAR BULB IN EN BLOC SUBTOTAL TEMPORAL BONE RESECTION FOR ADVANCED SQUAMOUS CELL CARCINOMA OF THE EXTERNAL AUDITORY CANAL: ANATOMICAL CONSIDERATION AND SURGICAL STRATEGIES.
Noritaka Komune1; Daisuke Kuga2; Satoshi Matsuo3; Osamu Akiyama4; Joe Iwanaga5; R. Shane Tubbs5; Takashi Nakagawa1; 1Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu University; 2Department of Neurosurgery, Graduate School of Medical Sciences, Kyushu University; 3Department of Neurosurgery, Fukuoka Tokushukai Hospital; 4Department of Neurosurgery, Juntendo University Faculty of Medicine; 5Department of Neurosurgery, Tulane Center for Clinical Neurosciences, Tulane University School of Medicine
Background and Objectives: Both lateral temporal bone resection (LTBR) and subtotal temporal bone resection are standard methods of en bloc resection for squamous cell carcinoma of the external auditory canal (EACSCC). Though en bloc subtotal temporal bone resection is a highly challenging procedure that necessitates a skull base team comprising neurosurgeons, otolaryngologists, head and neck surgeons, and plastic surgeons, en bloc resection aiming for negative margins is considered the most reliable treatment strategy for advanced squamous cell carcinoma of the external auditory canal (EACSCC). Literature indicates that subtotal temporal bone resection carries a high perioperative risk. This report retrospectively examines 5 cases of en bloc subtotal temporal bone resection performed at our department, considering the manipulating of the lower cranial nerves and the jugular bulb from a microsurgical anatomical perspective.
Materials and Methods: Retrospective observational study. This study includes 5 cases of subtotal temporal bone resection performed at our department between August 2018 and December 2023. The following factors were examined from patient charts and surgical videos: gender, age at initial consultation, TNM classification of EACSCC, anatomical tumor progression, histological type, postoperative margin evaluation, treatment, follow-up period, outcomes, postoperative lower cranial nerve paralysis, status of the venous sinus postoperatively, and presence of postoperative dysphagia. The manipulation of the lower cranial nerves and the jugular bulb was reviewed from surgical videos. Three-dimensional reconstructions of preoperative CT were used to evaluate the presence of a high jugular bulb and classify the glossopharyngeal meatus.
Results: The series included three females and two males, with a median age of 66 (57-78). There were four cases on the right side and one on the left. One patient died from the current illness eight months postoperatively, while the remaining four survived without recurrence (follow-up period: 19-40 months). A three-dimensional analysis of the jugular foramen revealed a high jugular bulb in one case (Case 2). All five cases exhibited a groove-type glossopharyngeal meatus; no semicanal or canal types were observed. There were no instances of intraoperative lower cranial nerve injury. In all cases, the nerves were identified caudal to C1 and preserved as they were traced toward the skull base and jugular foramen. Despite all cases exhibiting a groove-type glossopharyngeal meatus, careful dissection from the underside of the temporal bone, with sharp cutting of the surrounding tissues, preserved the nerves, preventing traction injuries.
Regarding the jugular bulb, venous wall separation from the jugular fossa was possible in all cases. One case with severe intraoperative venous wall injury showed no postoperative blood flow but had no symptoms postoperatively. In the other case, asymptomatic transverse to sigmoid sinuses occlusion on the operative side was detected postoperatively. No postoperative glossopharyngeal or vagus nerve paralysis was observed in any case.
Conclusion: In subtotal temporal bone resection, the glossopharyngeal nerve is considered the most vulnerable structure for paralysis when considering the anatomical course of the nerves. If the glossopharyngeal nerve is not adequately dissected from the temporal bone, forced traction of the resected temporal bone increases the risk of avulsion injuries.