Comparison between Far Lateral Approach, Far Medial Expanded Endonasal Approach, and Contralateral Transmaxillary Corridor to the Jugular Tubercle

Background: The jugular tubercle (JT) is a bony prominence between the basilar and condylar parts of the occipital bone, superior and anterior to the hypoglossal canal. The far lateral (FL) approach drills the JT extradurally, increasing the ventral brainstem access. The “far medial” (FM) approach allows direct access to ventrolateral lesions in the inferior clivus, while the contralateral transmaxillary corridor (CTM) offers a more lateral trajectory. This study compares the volume of JT removed, brainstem exposure, and surgical corridor between FL, FM, and CTM.

Methods: Using image guidance, 10 cadaveric specimens were dissected: in 10 sides, the JT was drilled through FM and CTM, and in 10 sides FL was performed. The surgical corridor (the space between hypoglossal canal, lower cranial nerves, and IAC) and the area of exposure (using brainstem points: dorsally, obex, and dorsal median sulcus at the C1 level; and ventrally, pontomedullary sulcus and ventral median sulcus at C1 level) were measured. These were also compared pre- and post-drilling via FL. A comparative subanalysis of EEA and CTM to the JT was conducted, evaluating the angle of surgical trajectory. Finally, CT scan volumetric measurements were used to compare approaches.

Results: The angle of surgical trajectory to the JT was significantly greater (p < 0.001) for CTM (33.8 ± 7.1 degrees) versus FM (14.3 ± 2.6 degrees). A significantly greater area of exposure (p < 0.001) was also observed by drilling the JT via FL (344.3 ± 76.6 mm² vs. 410.7 ± 78.1 mm²). The overall mean area of exposure was significantly wider (p  <0.001) with FL (410.7 ± 78.1 mm²) and CTM (436.8 ± 44.8 mm²) compared with FM (270.7 ± 21.9 mm²), but not different (p = 0.3) between FL and CTM. The surgical corridor, through cranial nerves, was significantly larger (p < 0.001) via FL (177.3 ± 30.6 mm²) than FM (82.7 ± 12.4 mm²). The CTM also provided a greater surgical corridor than FM (212.2 ± 32.2 mm², p < 0.001) and there was a clear trend to greater exposure after CTM compared with FL (p = 0.05). The mean percentage of JT resected by each approach was 56.7% for FL, 40.4% for FM, and 94% for CTM.

Conclusion: The open and endoscopic approaches are complementary to each other for lesions in the inferior clival/petroclival region, where the location of the lower cranial nerves plays a significant role. The CTM approach is a feasible extension to the standard EEA, increasing the angle of the corridor and providing greater exposure than the FM. A substantially greater volume of the JT can be drilled via CTM than FL and FM, making this approach preferred when there is a bony lesion involving the JT.

Fig. 1 Far-lateral transcondylar transtubercular approach.

Fig. 2 Surgical corridor in a right side far lateral approach: (A) pre- and (B) post-drilling.

Fig. 3 Endoscopic anatomy of the inferior clivus after drilling the JT from CTM.

Fig. 4 Angle of surgical trajectory through ipsilateral nostril (A), contralateral nostril (B), and CTM (C).

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
12 February 2021