Introduction: The microscopic transoral, endoscopic transnasal, and endoscopic transoral approaches are used alone and in combination for a variety of craniovertebral junction (CVJ) pathologies. The endoscopic transoral approach provides a direct exposure not restricted by the nasal cavity, pterygoid plates, and palate while sparing the potential morbidities associated with extensive soft-tissue dissection, palatal splitting, or mandibulotomy. Concerns regarding the extent of visualization afforded by the endoscopic transoral approach may be limiting its widespread adoption.
Methods: A dissection of 10 cadaver heads was undertaken. CT-based imaging guidance was used to measure the working corridor of the endoscopic transoral approach. Measurements were made relative to the palatal line. The built-in linear measurement tool was used to measure the superior and inferior extents of view. The superolateral extent was measured relative to the midline (defined by the nasal process of the maxilla). The height of the clivus, odontoid tip, and superior aspect of the C-1 arch were measured relative to the palatal line.
Results: The CVJ was accessible in all cases. The superior extent of the approach was a mean 19.08 mm above the palatal line (range:11.1-27.7 mm). The superolateral extent relative to the midline was 15.45 mm on the right (range:9.6-23.7 mm) and 16.70 mm on the left (range:8.1-26.7 mm). The inferior extent was a mean 34.58 mm below the palatal line (range:22.2-41.6 mm). The mean distances were as follows: palatal line-odontoid tip, 0.97 mm (range:-4.9 to 3.7 mm); palatal line-clivus, 4.88 mm (range:-1.5 to 7.3 mm); palatal line-C-1 arch, -2.75 mm (range:-5.8 to 0 mm).
Conclusions: The endoscopic transoral approach reliably accesses the CVJ. This approach avoids the morbidities associated with palate-splitting (velopharyngeal insufficiency) and the expanded endonasal approach (mucus crusting, sinusitis, and potential carotid artery injury). For appropriately selected lesions near the palatal line, the endoscopic transoral approach appears to be the preferred approach.
Patient Care: Increase awareness of and provide laboratory support for the use of the less morbid endoscopic transoral approach to craniovertebral junction lesions
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Understand the reach of the working corridor of the endoscopic transoral approach 2) Describe the strengths and weaknesses of surgical approaches to the CVJ 3) Identify that the endoscopic transoral approach may be the preferred approach to CVJ lesions centered at the palatal line