Endoscopic single stage trans-oral decompression and anterior C1 lateral mass and C2 pedicle stabilization for atlanto-axial dislocation.

Abstract

Although most of the cases of atlanto-axial dislocation (AAD) and basilar invasion can be managed by posterior approaches in the recent times, anterior decompression with stabilization is required in selected patients who persist with irreducible AAD even after manipulation of the C1-C2 facet joint under general anesthesia. A single stage endoscopic trans-oral decompression and stabilization can be used in such patients. It has not been described so far to the best of authors' knowledge. This is indicated in irreducible AAD with the mandibular angle lying below the C2-C3 disc space. It is not a proper choice when the mandibular angle is above the C2-C3 disc space, there is involvement of the facet joint by trauma or any other pathologies, and if a posterior compression at the cervicomedullary junction persists. All patients should undergo pre-operative radiographs, computed tomography (CT) scan and magnetic resonance imaging with angiogram of the cranio-vertebral region. Utilizing this technique, an intra-operative satisfactory reduction of the dislocation with C1-C2 stabilization could be achieved in 3 patients, and 7 required an additional odontoid excision. Post- operative plain radiographs should be performed to assess for C1- C2 alignment and fusion at 3 and 12 months after surgery. All 10 patients of our series had an irreducible AAD and two had an additional basilar invasion. All patients improved from the pre-operative Ranawat grade 3A (n = 8) and 3B (n = 2) to post-operative grade 1 (n = 9) and 2 (n = 1) at a 3-12- month follow-up assessment. The average duration of the procedure and blood loss was 145 minutes and 75 ml, respectively. Endoscopic trans-oral single stage decompression and stabilization seems to be an effective and safe alternative in selected patients with AAD and basilar invasion.