Staged Repositioning in Endoscopic Endonasal Odontoidectomy Maximizes Decompression while Allowing Preservation of the C1 Anterior Arch: A Technical Note.

Background Preservation of the anterior arch of C1 in endoscopic endonasal odontoidectomy has been proposed as an alternative to complete C1 arch resections, potentially affording less destabilization of the craniocervical junction. Nonetheless, this approach may limit the decompression achieved. In this case, intra-operative repositioning allowed maximal decompression while preserving the anterior arch of C1. Case Description A 79-year-old woman presented with suboccipital pain caused by an expansile and compressive mass centered on the dens. Notably, the mass occluded both vertebral arteries resulting in small cerebellar strokes. An endoscopic endonasal approach for diagnosis and decompression was performed followed by posterior fixation. Given the significant compression, the patient was initially positioned in slight cervical extension. After rhinopharyngeal flap harvest, the top half of the anterior arch of C1 was resected, maintaining its structural integrity. The odontoidectomy was completed flush to the superior border of the reduced C1 arch. After an intra-operative CT scan, performed in a neutral position, the patient was then repositioned with cervical flexion. This maneuver presented the residual odontoid above the C1 arch, but given the partial removal of the dens, it did not result in any change in neuromonitoring. Further odontoid resection was then completed and follow-up CT scan revealed maximal dens removal, which extended below the C1 anterior arch in neutral position. Conclusion In cases of odontoid/atlantoaxial pathology causing significant neural compression, staged intra-operative repositioning can safely maximize the odontoidectomy, while affording preservation of the structural integrity of the anterior arch of C1.