No increased incidence of tethered cord syndrome or low-lying conus in pediatric Chiari malformation type I.

Abstract

Objective: The relationship between Chiari malformation type I (CMI) and tethered cord syndrome (TCS) is not well understood. The aim of this study was to examine conus position and rates of TCS and tethered cord release (TCR) in pediatric patients with CMI at a tertiary hospital.

Methods: The medical records of children with a diagnosis of CMI based on MRI of the lumbar spine from 2010 to 2023 were retrospectively reviewed. Conus position on MRI, tonsil position below the foramen magnum, presence of fatty filum or filum terminale lipoma, and rates of CMI decompression and TCR were recorded. Age- and sex-matched controls were randomly selected from a cohort of patients who obtained an MRI of the spine for any reason. Conus position was coded and then compared using the Student t-test. Categorical variables were compared using the chi-square test.

Results: A total of 657 pediatric patients with CMI were included. The mean ± SD tonsil position was 11.7 ± 5.6 mm below the foramen magnum, and 44.7% of patients underwent CMI decompression. The conus terminated at or above the L2-3 disc space in 97% of CMI patients. There was no statistical difference in conus position between CMI patients and controls (p = 0.09). Nine patients (1.4%) in the CMI cohort had symptomatic TCS and underwent TCR. This proportion was not statistically different compared to the control group: 11 patients (1.7%) had symptomatic TCS and underwent TCR (p = 0.1).

Conclusions: Most patients with CMI had a normal conus position (97%), and conus position was not different between CMI and control patients. The number of patients with symptomatic TCS was not statistically different between CMI and control patients.