Award: AAP/SONS Award

Authors: Gabrielle Johnson; Albert Isaacs, MD; Alexander Yahanda, MS; Travis CreveCoeur, MD; Jennifer Strahle, MD; T.S. Park, MD; David Limbrick, MD, PhD (St. Louis, MO)

Introduction:

Posterior fossa decompression (PFD) is accepted as the primary treatment for Chiari I malformation (CM) and syringomyelia (SM), but there is limited guidance on management of CM+SM in the presence of complex craniovertebral junction (CVJ) anomalies. The objective of this study was to examine the clinical, surgical, and radiological outcomes of children with CM+SM and complex CVJ parameters.

Methods:

We analyzed the Park-Reeves Syringomyelia Research Consortium (PRSRC) database to evaluate clinical, surgical, and radiological outcomes of children with tonsillar position ≥ 5 mm below McRae’s line and syrinx diameter ≥ 3 mm. Clivoaxial angle (CXA) ≤125º, pB-C2, basilar invagination (BI), and obex position (in mm, relative to McRae’s line) were recorded. Complex CVJ was defined as CM+SM with CXA ≤125º, pB-C2 ≥9 mm, BI, or obex position below McRae’s line.

Results:

The above CVJ parameters were measured in 993 PRSRC participants with clinical and radiological data. Four-hundred seventeen participants were classified as having complex CVJ, and 31 participants went on to have occipital-cervical fusion (OCF) with or without ventral decompression (VD) at a mean of 4.3 ± 11.1 months after PFD. Participants with complex CVJ who underwent PFD but not OCF±VD had a similar clinical presentation, clinical response to surgery, and PFD revision rate as participants with normal CVJ parameters. Notably, compared to subjects with complex CVJ who underwent PFD only, those who required OCF±VD presented with worse bulbar signs, balance/gait ataxia, cranial nerve deficits, and reflex abnormalities.

Conclusion:

Clinical findings including bulbar signs/cranial nerve deficits, gait ataxia, and reflex abnormalitiesdrive the use of OCF±VD. In the absence of these findings, individuals with CM+SM and complex CVJ have similar outcomes to those with CM+SM alone.