Surgical failures and revision strategies in Basilar invagination: an exploratory analysis of 145 published cases.

INTRODUCTION

Basilar invagination (BI) is a congenital or acquired anomaly of the craniovertebral junction, often accompanied by atlantoaxial dislocation (AAD), Chiari malformation, and syringomyelia, leading to brainstem and cervical spinal cord compression. Surgical failures typically result from inadequate ventral decompression or failure to achieve craniovertebral stability, necessitating technically demanding revision procedures. However, evidence regarding revision strategies and their outcomes remains limited. Therefore, this study aimed to identify the primary procedures associated with failure, characterize revision techniques, and compare outcomes and complications across surgical strategies.

METHOD: We conducted a systematic review analyzing 145 patients from 14 studies who underwent revision surgery for BI. Eligible studies reported both the failed primary surgery and revision outcomes. Data on demographics, prior procedures, revision techniques, radiological and neurological outcomes, and complications were extracted and analyzed descriptively.

RESULTS

Posterior fossa decompression (PFD) was the most common failed initial procedure (92/145, 63.4%), followed by occipitocervical fusion (OCF) (35/145, 24.1%), posterior C1-C2 fixation (12/145, 8.3%), and anterior decompression (6/145, 4.1%). The leading cause of revision was structural failure or persistent instability (95/145, 65.5%), particularly after PFD (41.4%) and OCF (16.6%). Revision surgerier focusing stabilization achieved neurological improvement and optimal radiological alignment in 116 patients (80%). The procedures with the highest success rates were seen with anterior decompression (51/145, 35.2%), posterior C1-C2 fixation (37/145, 25.5%), and OCF (28/145, 19.3%). Overall, the complications were low, with 73.8% of patients experiencing no adverse events following revision.

CONCLUSION

Surgical failures in BI are predominantly due to inadequate stabilization following decompression-alone procedures. Revision strategies that restore craniovertebral stability provide the best outcomes, highlighting the need for comprehensive, stability-focused surgical planning.