Cerebellar herniation in syringomyelia: relation between tonsillar herniation and the dimensions of the syrinx and the remaining spinal cord. A quantitative MRI study.

The dimensions of the syrinx, the remaining spinal cord and the degree of cerebellar herniation were analyzed by one- and two-dimensional MRI studies in 22 patients with syringomyelia. A deep and/or broad cyst tends to be a long one. The dimensions of the syrinx and the spinal cord have an inverse relationship. The degree of cerebellar herniation is not related to the longitudinal or transverse extension of the cyst or the ratio cyst/cord or the remaining spinal cord (neither for diameters nor for cross-sectional areas). The dimensions of cysts are not significantly greater in patients with tonsillar herniation than in patients without. We conclude that cerebellar herniation is not a major prognostic factor and should not be overestimated for the development and progression of the disease.