MATERIAL and METHODS: Forty-three patients with reducible AAD, BI and CHM with syringomyelia underwent surgery from January 2009 to January 2013. Intraoperative restoration followed by posterior decompression and plate-rod placement with occipital cortical screws and C2/C3 lateral mass cortical screws fixation devices were used in all patients. Results were recorded both pre- and postoperatively and these outcome measures included Nurick grading (NG) and radiology findings (atlantodental interval (ADI), space available for the spinal cord (SAC), interval between odontoid and Chamberlain’s line (IOC), and the cervicomedullary angle (CMA)).

RESULTS: Forty (93%) of the 43 patients were followed up. Thirty-six (90%) patients’ symptoms improved and four (10%) stabilized. No patients became progressively worse. The difference between preoperative and postoperative Nurick grades was statistically significant. All patients achieved restoration, including thirty (75%) patients had full restoration and ten (25%) had part restoration. The size of syringomyelia was obviously decreased in 32 (80%) patients and stable in 8 (20%) patients. All radiology findings (ADI, IOC, SAC, CMA) showed significant changes from pre- to postoperative (p < 0.01).

CONCLUSION: Intraoperative distraction, extension combined posterior decompression with use of plate-rod-screws occipitocervical fusion device is an effective method to treat AAD, BI and CHM with syringomyelia. Keywords : Atlantoaxial dislocation, Basilar invagination, Chiari malformation, Syringomyelia, Occipitocervical fusion