The endoscopic endonasal eustachian tube anterolateral mobilization strategy: minimizing the cost of the extreme-medial approach

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>The ventral jugular foramen and the infrapetrous region are difficult to access through conventional lateral and posterolateral approaches. Endoscopic endonasal approaches to this region are obstructed by the eustachian tube (ET). This study presents a novel strategy for mobilizing the ET while preserving its integrity. Qualitative and quantitative comparisons with previous ET management paradigms are also presented.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>Ten dry skulls were analyzed. Four ET management strategies were sequentially performed on a total of 6 sides of cadaveric head specimens. Four measurement groups were generated: in group A, the ET was intact and not mobilized; in group B, the ET was mobilized inferolaterally; in group C, the ET underwent anterolateral mobilization; and in group D, the ET was resected. ET range of mobilization, surgical exposure area, and surgical freedom were measured and compared among the groups.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>Wide exposure of the infrapetrous region and jugular foramen was achieved by removing the pterygoid process, unroofing the cartilaginous ET up to the level of the posterior aspect of the foramen ovale, and detaching the ET from the skull base and soft palate. Anterolateral mobilization of the ET facilitated significantly more retraction (a 126% increase) of the ET than inferolateral mobilization (mean ± SD: 20.8 ± 11.2 mm vs 9.2 ± 3.6 mm [p = 0.02]). Compared with group A, groups C and D had enhanced surgical exposure (142.5% [1176.9 ± 935.7 mm<jats:sup>2</jats:sup>] and 155.9% [1242.0 ± 1096.2 mm<jats:sup>2</jats:sup>], respectively, vs 485.4 ± 377.6 mm<jats:sup>2</jats:sup> for group A [both p = 0.02]). Furthermore, group C had a significantly larger surgical exposure area than group B (p = 0.02). No statistically significant difference was found between the area of exposure obtained by ET removal and anterolateral mobilization. Anterolateral mobilization of the ET resulted in a 39.5% increase in surgical freedom toward the exocranial jugular foramen compared with that obtained through inferolateral mobilization of the ET (67.2° ± 20.5° vs 48.1° ± 6.7° [p = 0.047]) and a 65.4% increase compared with that afforded by an intact ET position (67.2° ± 20.5° vs 40.6° ± 14.3° [p = 0.03]).</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>Anterolateral mobilization of the ET provides excellent access to the ventral jugular foramen and infrapetrous region. The surgical exposure obtained is superior to that achieved with other ET management strategies and is comparable to that obtained by ET resection.</jats:p></jats:sec>

Role of resection of torus tubarius to maximize the endonasal exposure of the inferior petrous apex and petroclival area

“…Although sufficient exposure following anterolateral mobilization of the Eustachian tube could be achieved, the procedure harbors significant trauma and carries risk of copious bleeding from ascending pharyngeal artery and deep pterygoid plexus. 16 The present study suggests that removal of the torus tubarius can also satisfy the demands for exposure of the inferior petrous apex and petroclival region while preserving the pharyngeal orifice of the Eustachian tube. Moreover, a full direct access to the inferior petrous apex and the jugular foramen could be achieved also.…”

“…Resection of the Eustachian tube can increase exposure of the inferior petrous apex and petroclival region by 3‐fold, and the freedom of maneuverability in the lateral and inferior direction is also increased 24 . Resection of the Eustachian tube 16 and, alternatively, the anterolateral mobilization of the Eustachian, 16 where the structures in both the pterygopalatine fossa and the infratemporal fossa need to be displaced or transected, could yield excellent exposure and surgical freedom of the inferior petrous apex and the ventral jugular foramen. Although sufficient exposure following anterolateral mobilization of the Eustachian tube could be achieved, the procedure harbors significant trauma and carries risk of copious bleeding from ascending pharyngeal artery and deep pterygoid plexus 16 .…”

“…Resection of the Eustachian tube 16 and, alternatively, the anterolateral mobilization of the Eustachian, 16 where the structures in both the pterygopalatine fossa and the infratemporal fossa need to be displaced or transected, could yield excellent exposure and surgical freedom of the inferior petrous apex and the ventral jugular foramen. Although sufficient exposure following anterolateral mobilization of the Eustachian tube could be achieved, the procedure harbors significant trauma and carries risk of copious bleeding from ascending pharyngeal artery and deep pterygoid plexus 16 . The present study suggests that removal of the torus tubarius can also satisfy the demands for exposure of the inferior petrous apex and petroclival region while preserving the pharyngeal orifice of the Eustachian tube.…”

“…Simal et al proposed the transposition of the cartilaginous Eustachian tube for exposure; however, the applicability of this approach is sometimes limited 15 . Labib et al demonstrated that anterolateral mobilization of the Eustachian tube can achieve an exposure and surgical freedom of the ventral jugular foramen and the infrapetrous region that is similar to those achieved by the resection of the Eustachian tube 16 . Taniguchi et al proposed resecting the fibrocartilage superior to the Eustachian tube to access the inferior petrous apex while preserving Eustachian tube function 17 .…”

“…15 Labib et al demonstrated that anterolateral mobilization of the Eustachian tube can achieve an exposure and surgical freedom of the ventral jugular foramen and the infrapetrous region that is similar to those achieved by the resection of the Eustachian tube. 16 Taniguchi et al proposed resecting the fibrocartilage superior to the Eustachian tube to access the inferior petrous apex while preserving Eustachian tube function. 17 Although the technique has been applied successfully in clinical cases, the narrow area for maneuverability is technically challenging; therefore, the management of lesions such as chondrosarcoma or chordoma involving the petroclival region is technically highly demanding through this corridor.…”