Complex Chiari Malformations Diagnosis, Evaluation, and Treatment

Patients with CCM may be at risk for surgical fail-ure if standard surgical techniques for treatment of CM are used; in some cases, reoperation and OCF with or without VBD may be required. We recom-mend a methodical approach to the management of these patients, with focus on clinical symptoms, most notably bulbar symptoms and myelopathy. Radiographic data including the C-C2SVA, CXA, and pBC2 can be useful in guiding management. Specifically, patients with C-C2SVA of 5 mm or greater and CXA of less than 125 degrees represent a more high-risk phenotype. Careful follow-up, monitoring of symptoms, and consideration of additional surgery in the setting of failure after PFDD in this high-risk cohort are necessary.