Surgical Treatment of Basilar Invagination

Study Design. A systematic literature review and consensus using Delphi method. Objective. This review aims to outline the therapeutic criteria and clarify the best surgical options for the different types of basilar invagination (BI). Summary of Background. BI is a complex developmental malformation for which many surgical remedies have been proposed without clear consensus. Material and Methods. Using PubMed, the authors reviewed the literature on the surgical treatment of BI published from 2011 to 2022 looking at different surgical options. A panel of spine surgeons and members of the WFNS Spine Committee used the Delphi technique to assess the strength of literature, elaborate, and vote on statements regarding the surgical management of BI. Results. Thirteen recommendations were issued covering the most relevant topics related to the surgical treatment of BI. Posterior fossa decompression alone is an option to treat BI without instability. Most cases of BI and AAI can be treated by C1-C2 fixation. In selected cases, distraction of the atlantoaxial joint may be required. Current evidence is lacking which technique is better to correct irreducible BI. OCF can be used in case of atlas assimilation, dysgenesis of C1 lateral mass, in irreducible cases, odontoidectomy and revision of failed C1-C2 fixation. Complications of the OCF may reach up to 50%. The role for anterior fusion for treatment of BI need to be better assessed by further studies. In the setting of irreducible anterior compression caused by BI, the anterior odontoidectomy can be indicated supplemented by C1-C2/occipital-cervical fusion. Conclusions. There are multiple surgical options for basilar invagination depending on the existence of compression, AAD or irreducibility. The WFNS spine committee proposed consensus recommendations based on relevant literature published after 2011 to help surgeons standardize the level of care and improve outcomes following treatment across the globe.