Chiari malformation Type I and syrinx in children undergoing magnetic resonance imaging

Clinical article

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Object

Chiari malformation Type I (CM-I) with an associated spinal syrinx is a common pediatric diagnosis. A better understanding of the relative age-related prevalence and MR imaging characteristics of these associated conditions may lead to improved treatment decisions.

Methods

The authors performed a retrospective review of 14,116 consecutive individuals 18 years of age or younger who had undergone brain or cervical spine MR imaging at the University of Michigan between November 1997 and August 2008. In the patients with CM-I, demographic, clinical, and radiographic information was recorded.

Results

Five hundred nine children (3.6%) with CM-I were identified. Among these patients, 23% also had a spinal cord syrinx, and 86% of the syringes were found in the cervical spine. The MR imaging prevalence of CM-I with a syrinx was 1.2% in girls and 0.5% in boys (p < 0.0001). The severity of impaired CSF flow at the foramen magnum was associated with the amount of tonsillar herniation (p < 0.0001) and conformation of the tonsils (p < 0.0001). Patients with CM-I were treated surgically in 35% of cases; these patients exhibited more severe tonsillar herniation (p < 0.0001) and impaired CSF flow (p < 0.0001) as compared with those who did not undergo surgery. On imaging, 32% of all the patients with CM-I were considered symptomatic by the treating physician. Patients were more likely to be considered symptomatic if they were female, had a syrinx, displayed abnormal tonsillar pulsations, or had a greater amount of tonsillar herniation.

Conclusions

In this study the authors describe the age-related prevalence and MR imaging characteristics of CM-I and its association with a syrinx and other abnormalities in a large group of children who underwent MR imaging for any indication. Syringes are more common in older children, in girls, and in patients with a greater degree of tonsillar descent and CSF flow impairment.

Abbreviations used in this paper: CM-I = Chiari malformation Type I; EMERSE = Electronic Medical Record Search Engine.

Article Information

Address correspondence to: Cormac O. Maher, M.D., Department of Neurosurgery, University of Michigan, 1500 East Medical Center Drive, Room 3552, Taubman Center, Ann Arbor, Michigan 48109-5338. email: cmaher@med.umich.edu.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Line graph reflecting the percentage of children, according to age (in years), in whom a diagnosis of CM-I was made at the time of MR imaging.

  • View in gallery

    Line graph depicting the percentage of children with CM-I, according to age (in years), in whom spinal syrinx was diagnosed on MR imaging.

  • View in gallery

    Bar graph illustrating the number of patients with CM-I alone (black bars) versus those with both CM-I and syrinx (gray bars), according to the measurement (in mm) of tonsillar descent below the foramen magnum. Those with greater amounts of tonsillar decent were more likely to have an associated syrinx.

  • View in gallery

    Bar graph showing the cranial extent of syrinx in patients at the time of the initial syrinx diagnosis, according to the adjacent vertebral level.

  • View in gallery

    Bar graph showing the patients treated with decompression (black bars) versus without surgery (gray bars), according to age (in years).

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