Anterior Retropharyngeal Cage Distraction and Fixation for Basilar Invagination: “The Wedge Technique”

Abstract

Objective: Surgery is indicated for basilar invagination (BI) in symptomatic patients. In many patients, symptoms and signs occur due to an upward-migrated and malaligned odontoid with fixed or mobile atlantoaxial instability. Posterior distraction and fixation of the atlantoaxial joints has evolved to become the standard of care, but has some inherent morbidity. In this study, we propose that the unilateral anterior submandibular retropharyngeal approach with customized wedge-shaped titanium cages inserted into both atlantoaxial joints and anterior atlantoaxial fixation with a plate screw construct is a safer and easier option in many cases of BI. Methods: From February 2014 to February 2019, 52 patients (age range, 15-78 years; 40 males and 12 females) with symptomatic BI with atlantoaxial dislocation and minimal sagittal facetal inclination and only mild Chiari malformation without syringomyelia were offered anterior submandibular retropharyngeal atlantoaxial distraction and fixation surgery. Results: Neurological improvement occurred in 80% of patients, while the neurological status of 20% remained unchanged. No patients worsened, and no major complications or mortality was observed. Conclusion: In properly selected cases of symptomatic BI, anterior wedge cage distraction with anterior atlantoaxial fixation is a safe and simple option.

Basilar Invagination: Surgical Treatment by Novel Anterior Implant

“…In appropriately selected cases (angle of the mandible is at or above the C2-3 disc in lateral X-ray in extension), the atlantoaxial joints can easily and safely be approached anteriorly in supine position by a unilateral submandibular retropharyngeal approach as described earlier [ 18 , 19 , 20 ].…”

Unstable odontoid fractures: technical appraisal of anterior extrapharyangeal open reduction internal fixation for irreducible unstable odontoid fractures. Patient series

“…19 The anterior approach for atlantoaxial stabilization has been described in literature. [20][21][22][23] The anterior extrapharyngeal VSP plate screw fixation for odontoid fractures can be performed in most cases (more than 95%) when, on extension, the angles of the mandible are at or above the C2-3 disc space on a lateral radiograph. 24,25 The unilateral anterior extrapharyngeal approach to both the atlantoaxial joints is without any risk to the vertebral arteries and preserves the C2 root.…”

Anterior retropharyngeal cage distraction with atlantoaxial plate-screw fixation for basilar invagination with atlantoaxial dislocation

“…This is an example of anterior surgery with long-term result showing rigid fusion. Cages up to 9 mm can be used to achieve distraction and realignment (Patkar, 2019;Menon 2019).…”