Manipulation of the Lower Cranial Nerves and Superior Jugular Bulb During Subtotal Temporal Bone Resection for Advanced Temporal Bone Malignancies: Anatomical Considerations and Surgical Strategies.

INTRODUCTION: En bloc subtotal temporal bone resection (STBR) is challenging. En bloc resection aiming for negative margins is considered the most reliable treatment strategy for advanced squamous cell carcinoma of the external auditory canal. However, the literature indicates that STBR carries a high perioperative risk. This report retrospectively examines 5 cases of en bloc STBR, considering the manipulating of the lower cranial nerves and the superior jugular bulb (SJB) from a microsurgical anatomical perspective.

METHODS: Retrospective observational study. This study includes 5 cases of STBR performed at a single tertiary institution between August 2018 and December 2023. The clinical factors were examined from patient charts and surgical videos. The manipulation of the lower cranial nerves and the SJB was reviewed from surgical videos. Three-dimensional reconstructions of preoperative computed tomography were used to evaluate the presence of a high jugular bulb and classify the glossopharyngeal meatus.

RESULTS: No postoperative glossopharyngeal or vagus nerve paralysis was observed in any case. All 5 cases exhibited a groove-type glossopharyngeal meatus. There were no instances of intraoperative lower cranial nerve injury. 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 SJB, venous wall separation from the jugular fossa was possible in all cases.

CONCLUSION: With appropriate preoperative assessment and intraoperative surgical techniques, lower cranial nerve palsy can be avoided, and dissection of the SJB is possible.