Abstract
BackgroundThere is an ongoing controversy about the significance of tonsillar ectopia among patients with idiopathic scoliosis (IS).AimTo find out if tonsillar ectopia occurs more frequently among patients with IS and if it plays any etiological or prognostic role in IS.Study designRetrospective study.MethodsRetrospective analysis of 155 consecutive spine MRIs (79 patients with IS and 76 controls; aged 7-25 years; 55% were female) with regard to the position of the cerebellar tonsils in relation to foramen magnum and the sagittal diameter of foramen magnum. All images were evaluated independently by two neuroradiologists. Interobserver and intraobserver reliability analysis was performed by calculation of κ-value, intraclass correlation coefficient, and systematic and random errors. The occurrence of tonsillar ectopia among patients with IS and controls was estimated and the association of tonsillar ectopia with different predictors has been tested. Statistical significance was set to P ≤ 0.05.ResultsThe interobserver and intraobserver agreement with regard to the occurrence of tonsillar ectopia was almost perfect (κ 0.84 and 0.89, respectively). Tonsillar ectopia was found in 37% of patients with IS compared with 13% among controls (p < 0.001 and odds ratio of 3.8, 95% CI 1.7-8.5). The occurrence of tonsillar ectopia was not associated with the severity of scoliotic deformity (p = 0.85), or rapid progression of scoliosis (p = 0.76). Neurological deficit occurs twice as frequently in patients with tonsillar ectopia as in those with no tonsillar ectopia. Two of five patients with tonsillar ectopia showed improvement of their neurological deficit after the surgical correction of scoliosis.ConclusionAs tonsillar ectopia is significantly more frequent among patients with IS and may exhibit some prognostic utility in patients with neurological deficit, we forward the hypothesis that tonsillar ectopia may play a role in the development of the deformity in some patients with IS. However, occurrence of tonsillar ectopia among 13% of controls precludes stating a definitive role of tonsillar ectopia in the pathogenesis of IS. Some patients with IS, tonsillar ectopia and neurological deficit showed neurological improvement following the surgical correction of scoliosis.
Highlights
There is an ongoing controversy about the significance of tonsillar ectopia among patients with idiopathic scoliosis (IS)
Tonsillar ectopia was found in 37% of patients with IS compared with 13% among controls (p < 0.001 and odds ratio of 3.8, 95% confidence interval (95% CI) 1.7-8.5)
Some patients with IS, tonsillar ectopia and neurological deficit showed neurological improvement following the surgical correction of scoliosis
Summary
There is an ongoing controversy about the significance of tonsillar ectopia among patients with idiopathic scoliosis (IS). Scoliosis with structural abnormalities are classified according to the nomenclature of the Scoliosis Research Society (SRS), which was developed in 1969, and later modified in 1970 and 1973 [1,2]. Syringomyelia, Chiari malformations, tethered cord, diastematomyelia and meningocele/myelomeningocele are among the structural abnormalities classified as neuropathic abnormalities. Chiari I malformation is characterized by tonsillar herniation, which is defined as descent of cerebellar tonsils ≥5 mm (≥6 mm in patients younger than 10 years) below the bony border of the foramen magnum [3]. Herniation of cerebellar tonsils of
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