2025 Proffered Presentations
S261: LIMITS OF ENDOSCOPIC CONTRALATERAL TRANSMAXILLARY APPROACH TO JUGULAR FORAMEN: AN ANATOMICAL STUDY
Ivo Petoe; Hussam Abou-Al-Shaar; Ling Xia; Garret Choby; Georgios A Zenonos; Carl H Snyderman; Eric Wang; Paul A Gardner; University of Pittsburgh Medical Center
Introduction: Lesions arising from the pars nervosa of the jugular foramen represent a challenge given their location antero-medial to the pars venosa. Therefore visualization of the anterior extension of such lesions is limited and lateral access blocked by the pars venosum. The endonasal extreme medial approach has been introduced to overcome these limitations and provide direct ventral access to the pars nervosa. However, the limits of this approach have not been established. An anatomical investigation was performed to define anatomical limits of this approach.
Methods: Dissections of 2 cadaveric (4 sides), latex-injected specimens were performed using 0 and 45 degree endoscopes, utilizing binostril and contralateral transmaxillary approach. Thin cut volumetric CT scans of the specimen were obtained prior to the dissection and registered with intraoperative navigation system (Q Guidance, Stryker©). The following measurements were taken utilizing the navigation system after the maximal extent of exposure was achieved: distance from the torus tubarius to the lateral most extent of exposure; the width of the working corridor from the medial (intracranial) end to the most laterally accessible part of jugular foramen; and the cranial and caudal limits of the approach. The measurements were taken before and after the bony floor of the petrous carotid canal was removed.
Results: In all four sides, the superior extent of exposure was the lower lip of the internal auditory canal. The inferior exposure was limited in all cases by the superior aspect of the hypoglossal canal, creating a cranio-caudal window of mean 20.4 mm (19.5-21.3). The mean length of the exposure measured from the torus tubaries of the eustachian tube to the furthest lateral limit was 21.45 (range 20-22.3 mm) before and 29.7 mm (range 29-31.2) after the removal of the petrous carotid canal floor (CCF). A mean of 8.28 mm (range 7.9-8.) of the CCF were removed. The width of the jugular tubercle exposure before the CCF removal was 6.5 mm (5.2-7.6) and 13.5 mm (range 12.6-14.8) after the CCF removal. After CCF removal, 180 degrees exposure of the pars nervosa was achieved.
Conclusion: Endoscopic endonasal approach to the jugular foramen is limited superiorly by the IAC, inferiorly by the hypoglossal canal and laterally by the floor of the petrous carotid canal. The CTM approach allowed access to the pars nervosa of the jugular foramen, however decreasing range of motion was observed with progressive lateral extent of the exposure as the removal of lower petrous apex and jugular tubercle created a funnel shaped working corridor. Partial removal/egg-shelling of the CCF doubles the antero-posterior exposure, increases the freedom of motion and allows for 180 degree exposure of the pars nervosa of the jugular foramen. Further study need to be performed to validate this data.