The Epidemiology of Syringomyelia

Introduction: Syringomyelia, fluid-filled cavities within the spinal cord, are often incidental findings on MRI and typically asymptomatic. Most cases are idiopathic, although a significant association exists with type I Chiari Malformations (CM-I). This study aims to examine the epidemiology of syringomyelia across various demographics and clinical features, providing insights for clinical decision-making.

Methods: A retrospective review was conducted at a tertiary care center, covering MRI scans from 1995-2023. Demographic and clinical data, including MRI indications, syringomyelia size and location, presumed etiology, and surgical intervention was collected. Syringomyelia were defined as fluid collections ≥3 mm in diameter or 25% of the spinal cord width in young children. Logistic regression, Chi-square tests, and one-way ANOVA were performed to analyze associations with demographic and clinical features.

Results: Of the 4,823 patients (45.4% male, average age 39.87 years), syringomyelia were present in 171 (3.5%) patients. The average syrinx measured 6.13 spinal segments long and 5.70 mm wide. Larger syrinx width, but not length, was statistically associated with a younger decade of life (p=0.036) and MRI indication (p < 0.001). Syrinxes linked to Chiari malformations were significantly larger than those related to scoliosis or congenital malformations (p < 0.001). Syringomyelia prevalence was highest in the first (46.8%) and second (22.2%) decades of life. For each additional decade, the odds of having a syrinx on imaging decreased by 44.2% (p < 0.001).

Conclusion : The study provides a novel characterization of syringomyelia and its association with various demographic and clinical features. Syringomyelia was more prevalent and syringes were larger in younger patients. The increased rates in earlier decades may reflect diagnostic and anatomical differences, with CM-I-associated syringomyelia frequently identified during childhood. These findings provide context for young patients and those with conditions such as CM-I, scoliosis, or congenital malformations with incidental syringomyelia.