Occipital-Cervical Fusion and Ventral Decompression in the Surgical Management of Chiari-1 Malformation and Syringomyelia: Analysis of Data From the Park-Reeves Syringomyelia Research Consortium.

Abstract

Occipital-cervical fusion (OCF) and ventral decompression (VD) may be used in the treatment of pediatric Chiari-1 malformation (CM-1) with syringomyelia (SM) as adjuncts to posterior fossa decompression (PFD) for complex craniovertebral junction pathology. To examine factors influencing the use of OCF and OCF/VD in a multicenter cohort of pediatric CM-1 and SM subjects treated with PFD. The Park-Reeves Syringomyelia Research Consortium registry was used to examine 637 subjects with cerebellar tonsillar ectopia≥5mm, syrinx diameter≥3mm, and at least 1 yr of follow-up after their index PFD. Comparisons were made between subjects who received PFD alone and those with PFD+OCF or PFD+OCF/VD. All 637 patients underwent PFD, 505 (79.2%) with and 132 (20.8%) without duraplasty. A total of 12 subjects went on to have OCF at some point in their management (PFD+OCF), whereas 4 had OCF and VD (PFD+OCF/VD). Of those with complete data, a history of platybasia (3/10, P=.011), Klippel-Feil (2/10, P=.015), and basilar invagination (3/12, P<.001) were increased within the OCF group, whereas only basilar invagination (1/4, P<.001) was increased in the OCF/VD group. Clivo-axial angle (CXA) was significantly lower for both OCF (128.8± 15.3°, P=.008) and OCF/VD (115.0± 11.6°, P=.025) groups when compared to PFD-only group (145.3± 12.7°). pB-C2 did not differ among groups. Although PFD alone is adequate for treating the vast majority of CM-1/SM patients, OCF or OCF/VD may be occasionally utilized. Cranial base and spine pathologies and CXA may provide insight into the need for OCF and/or OCF/VD.