Single-Stage Posterior Decompression and Occipitocervical Fusion Using aScrew-Rod-Plate System for Basilar Invagination with Anterior Spinal CordCompression and Craniocervical Instability

Purpose: To review our experience with surgical management of basilar invagination causing foramen magnum compression, focusing on selection of the surgical approach. Methods: Twelve consecutive patients underwent posterior foramen magnum decompression with occipitocervical fixation and fusion for treatment of basilar invagination causing brain stem compression and instability. Gentle traction and reduction during positioning of the patients also were performed. Ventral decompression (odontoid resection) was performed in none of the patients. Pre- and postoperative neurologic status was graded according to JOA and Nurick scales. Results: All patients had anterior spinal cord compression due to cranial settling of the cervical spinal column as well as instability at the craniocervical junction. The average follow-up period was 31 months (range, 24–42 months). All patients’ JOA and Nurick scores improved after surgery, but postoperative neurologic improvement and odontoid reduction were better in patients with atlas assimilation compared with patients with other pathologies. Conclusion: Odontoid reduction using an occipitocervical fixation system and decompression of the foramen magnum through a single-stage posterior approach is an effective treatment for basilar invagination, particularly in patients with atlas assimilation. Since odontoid reduction and foramen magnum decompression can be achieved through a single-stage posterior approach in most patients, odontoid resection should remain as a secondary procedure when these decompression efforts are insufficient.