gms | German Medical Science

Introduction: Syringomyelia can result in major functional disability. Conventional imaging techniques frequently fail to detect arachnoid adhesions as the underlying cause of the syringomyelia. Moreover a proposition whether the syringomyelia is of a dynamic type and might lead to neurological deficits shortly is so far not applicable. We hypothesize that fractional anisotropy (FA) derived from diffusion-tensor-imaging (DTI) computations is a sensitive parameter in syringomyelia to detect progressive cases.

Material and methods: Six patients with cervical syringomyelia and two healthy controls were examined. All underwent electrophysiological (SEP/MEP/silent period) recordings. Syringomyelia in all patients was comparable according size, shape and location. Imaging was performed at a 1.5 T with a six-element spine coil. Anatomical images were acquired with a 3D-CISS-sequence; DTI with an echo-planar-imaging sequence (thickness 5mm, b-value 800 s/mm2) using the GRAPPA-technique. The positions were centered around the syrinx, in the volunteers between the C2 and Th1. DTI-data were interpolated to a spatial resolution of 0.5 mm. After calculation of a diffusion tensor in each pixel, a FA-map was calculated and profiles of the FA-values across the spinal cord were calculated in all slices and compared with the profiles of the T2-weighted data-set.

Results: FA-values were lower at the level of all examined syringes and reach normal values beyond them. There were no pre-syrinx changes in the white matter tracts, no signs of FA-changes beneath the syrinx.

Conclusion: DTI Imaging of cervical syringomyelia demonstrate preserved white matter fibre tracts around and beyond the syrinx. This finding is consistent with preserved electrophysiological values in all studied patients despite a space occupying syringomyelia. FA-values were lower at the level of all examined syringes and reach normal values beyond them. There were no pre-syrinx changes in the white matter tracts, no signs of FA-changes beneath the syrinx. Nevertheless DTI-Imaging of the cervical spine provides quantitative information of pathological characteristics beyond the abnormalities visible on MRI.