Posterior Odontoidectomy Is Feasible When There Is Insufficiency of the Alar Ligaments

Introduction: Odontoidectomy is usually performed using a trans-oral approach. However, this approach is associated with high risks of infectious and wound closure complications. In this study we report of a patient treated with a posterior approach for odontoid process resection.

Methods: We present a 67 years old female, with a previous history of blood hypetension in treatment with medical therapy and diabities and a prior trauma 20 years earlier with loss of consciousness due to an heavy object that fell on her head from above.
The patient complained neck pain and stiffness, with severe limitation of head/neck movements. A CT scan of the CVJ documented basilar invagination associated with an os odontoideum. The basion-dens interval (BDI) of 12,14 mm (normal value < 8,5 mm), asymmetry of the odontoind that was displaced to the right, anterior atlo-dental interval (AADI) was 9,57 mm, posterior atlo-dental interval (PADI) was 6,26 mm, basion-axial interval (BAI) was 18,41 mm. MRI scan of the CVJ showed severe myelopathy due to extram compression of the bulbar-cervical spine junction.

Results: A suboccipital craniectomy followed with removal of a dural ring at the level of the foramen magnum. A right monolateral transpeducolar approach allowed to reach the base of the dens that was drilled and disconnected with the base of C2. At that point the dens was removed one-piece with a punch forceps. The removal was completed with the drilling of the os odontoideum. Intraoperative microdoppler was used to detect the omolateral vertebral artery. At the end of the procedure an occito-C3-C4 fixation and reduction was performed.

Conclusion : Posterior, monolateral transpeducolar approach is a viable option when alar ligaments are disrupted, offering a less invasive option especially in fragile and elderly patients.