Phenotypes and prognostic factors of syringomyelia in single-center patients with Chiari I malformation: moniliform type as a special configuration

Background: The specific association between morphometric characteristics of the syrinx and the prognosis of Chiari malformation type I (CM-I) with syringomyelia following surgical procedure seems to have not been elaborated. This study focused on the preoperative clinical and radiologic parameters in simple CM-I patients with syringomyelia to find out the relationship between the patients’ clinical status and the phenotypes of the syrinx with surgical outcome. Methods A continuous series of pediatric and adult patients with simple CM-I and syringomyelia from a prospectively maintained database in a single center were included, and we explored the related factors affecting the prognosis following decompression surgery through retrospective analysis of clinical presentations, imaging characteristics, and the morphological features of syringomyelia, to provide a clinical reference for the treatment of syringomyelia. Results There were 28 (13.8%) pediatric patients, and 174 adults (86.2%) included in our study. The average CCOS score was 14.56 ± 1.78. The overall prognosis after surgery was good in our series, among them 152 cases (75.25%) with a favorable prognosis, and syrinx was resolved effectively in 172 cases (85.15%). According to the univariate and multivariate analyses, the preoperative symptom duration, observation time, and with/without moniliform type were independent factors affecting the prognosis in adults. The most obvious difference between moniliform type and non-moniliform type lies in the patients with straightened cervical physio-curve or not, preoperative symptom duration, and ventral SAS. Conclusions Timely and effective decompression surgery could achieve a better outcome in CM-I patients with syringomyelia. Moniliform syringomyelia may suggest a relatively better prognosis.