CLINICAL ARTICLE J Neurosurg Pediatr 21:185–189, 2018 C hiari malformation Type I (CM-I), a developmen- tal abnormality of the hindbrain, is frequently as- sociated with syringomyelia and scoliosis. 13,31 The prevalence of scoliosis among patients with CM-I ranges from 13% to 36%. 1,3,5,29,31,33 In CM-I patients with a syrinx, the prevalence rises to 53%–85%. 8,15,17,30 Nearly 50% of patients with Chiari-related scoliosis (CRS) may require spinal fusion despite having undergone neurosurgical treatment. 8,9,25,31,34 Patients with CRS may manifest with “atypical” fndings, such as neurological defcit, a left api- cal curve, kyphotic deformity associated with the curve, or early onset. 16 Known risk factors for curve progression and early spinal fusion include older age at presentation, level of spinal deformity, less syrinx resolution, and greater de- gree of initial scoliosis. 2,3,16,24,27 Previous reports have addressed the short-term re- ABBREVIATIONS CCJ = craniocervical junction; CM = Chiari malformation; CM-I = CM Type I; CRS = Chiari-related scoliosis; CXA = clival-axial angle; SODD = suboc- cipital decompression and duraplasty. SUBMITTED June 9, 2017. ACCEPTED August 10, 2017. INCLUDE WHEN CITING Published online November 24, 2017; DOI: 10.3171/2017.8.PEDS17318. * Drs. Ravindra and Onwuzulike contributed equally to this work. Chiari-related scoliosis: a single-center experience with long-term radiographic follow-up and relationship to deformity correction *Vijay M. Ravindra, MD, MSPH, 1 Kaine Onwuzulike, MD, PhD, 2 Robert S. Heller, MD, 3 Robert Quigley, MD, 4 John Smith, MD, 4 Andrew T. Dailey, MD, 1 and Douglas L. Brockmeyer, MD 1 1 Department of Neurosurgery, University of Utah, Primary Children’s Hospital; 4 Department of Orthopedic Surgery, Primary Children’s Hospital, Salt Lake City, Utah; 2 Department of Neurosurgery, Cleveland Clinic, Cleveland, Ohio; and 3 Department of Neurosurgery, Tufts Medical Center, Boston, Massachusetts OBJECTIVE Previous reports have addressed the short-term response of patients with Chiari-related scoliosis (CRS) to suboccipital decompression and duraplasty (SODD); however, the long-term behavior of the curve has not been well defned. The authors undertook a longitudinal study of a cohort of patients who underwent SODD for CRS to determine whether there are factors related to Chiari malformation (CM) that predict long-term scoliotic curve behavior and need for deformity correction. METHODS The authors retrospectively reviewed cases in which patients underwent SODD for CRS during a 14-year period at a single center. Clinical (age, sex, and associated disorders/syndromes) and radiographic (CM type, tonsillar descent, pBC2 line, clival-axial angle [CXA], syrinx length and level, and initial Cobb angle) information was evaluated to identify associations with the primary outcome: delayed thoracolumbar fusion for progressive scoliosis. RESULTS Twenty-eight patients were identifed, but 4 were lost to follow-up and 1 underwent fusion within a year. Among the remaining 23 patients, 11 required fusion surgery at an average of 88.3 ± 15.4 months after SODD, including 7 (30%) who needed fusion more than 5 years after SODD. On univariate analysis, a lower CXA (131.5º ± 4.8º vs 146.5º ± 4.6º, p = 0.034), pBC2 > 9 mm (64% vs 25%, p = 0.06), and higher initial Cobb angle (35.1º ± 3.6º vs 22.8º ± 4.0º, p = 0.035) were associated with the need for thoracolumbar fusion. Multivariable modeling revealed that lower CXA was independently associated with a need for delayed thoracolumbar fusion (OR 1.12, p = 0.0128). CONCLUSIONS This investigation demonstrates the long-term outcome and natural history of CRS after SODD. The durability of the effect of SODD on CRS and curve behavior is poor, with late curve progression occurring in 30% of patients. Factors associated with CRS progression include an initial pBC2 > 9 mm, lower CXA, and higher Cobb angle. Lower CXA was an independent predictor of delayed thoracolumbar fusion. Further study is necessary on a larger cohort of patients to fully elucidate this relationship. https://thejns.org/doi/abs/10.3171/2017.8.PEDS17318 KEY WORDS Chiari decompression; scoliosis; deformity correction; suboccipital decompression and duraplasty; syrinx; syringopleural shunt; thoracolumbar fusion; clival-axial angle; Cobb angle; long-term follow-up; spine J Neurosurg Pediatr Volume 21 • February 2018 185 ©AANS 2018, except where prohibited by US copyright law Unauthenticated | Downloaded 05/16/22 08:49 PM UTC