Posterior reduction and internal fixation with posterior cranial fossa cranioectomy decompression for Chiari malformation type Ⅰ with basilar invagination, atlantoaxial subluxation, and syringomyelia

Abstract

Background Chiari malformation type Ⅰ(CM⁃Ⅰ) is one of the soft tissue anomalies in craniovertebral junction (CVJ). This kind of soft tissue anomaly usually develops with bone anomaly, such as atlantoaxial subluxation, basilar invagination, platybasia, C1 assimilation, etc. For these complex combined anomalies, the treatment remains unaddressed. This study was performed to evaluate the effect of posterior reduction and internal fixation with posterior cranial fossa cranioectomy decompression for Chiari malformation type Ⅰ with basilar invagination, atlantoaxial subluxation, and syringomyelia. Methods Patients with basilar invagination and atlantoaxial subluxation treated from July 2004 to September 2011 were reviewed. Including criterions were made to screen matching patients. Including patients were retrospectively analyzed on both clinical outcomes and radiographical results. Japanese Orthopaedic Association (JOA) score was used to evaluate the clinical outcomes, while the syrinx maximum size was measured on transverse view of MRI T2 image. The results were analyzed by SPSS 17.0 using t ⁃ text. Significant difference was considered when P ≤ 0.05. Results Fourteen patients met the including criterions, including 4 male patients and 10 female patients, with a mean age of 31.86 ± 11.36 (standard deviation, range: 17-51) years. Mean JOA score preoperatively of 14 patients was 13.07 ± 1.59 (standard deviation), while that was 15.57 ± 1.02 (standard deviation) postoperatively (t = 9.946, P = 0.000). The mean syrinx size was (7.05 ± 1.98) mm (standard deviation), while that was (2.21 ± 1.91) mm (standard deviation) postoperatively (t = 7.271, P = 0.000). There were no procedure⁃related morbidity or mortality happened. Conclusion Direct posterior reduction and internal fixation with posterior cranial fossa cranioectomy decompression can obviously improve the clinical outcomes and shrink syrinx for patients suffered from Chiari malformation typeⅠ with basilar invagination, atlantoaxial subluxation, and syringomyelia.

DOI：10.3969/j.issn.1672⁃6731.2012.04.009