Comparison of Intraspinal Abnormalities Prevalence in Congenital Scoliosis: Is Multiple Hemivertebra Associated with Higher Risk than Single Hemivertebra?

Background: The increasing utilization of magnetic resonance imaging has facilitated the detection of intraspinal abnormalities in congenital scoliosis (CS) caused by hemivertebra. However, the risk of intraspinal abnormalities across different hemivertebra patterns remains unclear. The aim of this study was to compare the prevalence of intraspinal abnormalities between single hemivertebra and multiple hemivertebra and identify key associated risk factors. Methods: A total of 1,048 patients with CS caused by hemivertebra who received surgical correction were included. The radiographic and clinical data for each patient were collected and analyzed. Results: Intraspinal abnormalities were present in 16.5% of patients, including syringomyelia (9.2%), lipoma filum terminale (6.0%), low-lying conus medullaris (3.1%), tethered spinal cord (2.9%), diastematomyelia (2.4%), and Chiari malformation (1.9%). Patients with multiple hemivertebra demonstrated a significantly higher intraspinal abnormalities incidence than those with single hemivertebra (24.4% vs. 14.1%, p < 0.001). In single hemivertebra (HV), 51 of 114 patients (44.7%) have intraspinal abnormalities located outside the region of bony HV, while the figure is 26 of 59 (44.1%) in patients with multiple HVs. Multivariate logistic regression showed that female sex [odds ratio (OR) = 1.800, p = 0.001], semisegmented/nonsegmented morphology (OR = 1.499, p = 0.003), and multiple hemivertebra (OR = 1.957, p = 0.001) are the risk factors of intraspinal abnormalities in all cases. Although 12.1% of all patients with intraspinal abnormalities had positive neurological findings, this was not statistically significant compared with those without intraspinal abnormalities (9.0%). Conclusion: Patients with multiple hemivertebra have a 1.96-fold higher risk of intraspinal abnormalities compared with those with a single hemivertebra. Importantly, intraspinal abnormalities are associated with female sex, multiple hemivertebra, and nonsegmented morphology, but not neurological symptoms, and caution should be paid to the intraspinal abnormalities outside of the bony lesions.