[MRT in primary and tumor-induced syringomyelia].

The MRI findings in 26 patients with primary syringomyelia and eight patients with a syrinx due to an intramedullary tumour were studied retrospectively. In general, the syrinx in the tumour cases resembled the appearance of primary syringomyelia. However, a specific and sensitive sign of tumour-induced syringomyelia was irregularity of the spinal cord close to the tumour (eight cases of eight), eccentric position of the lumen (seven of eight), and a diffuse increase of signal intensity on T2-weighted images (eight of eight). Primary syringomyelia also showed increased signal intensity on T2-weighted images outside the lumen, but this was closely related to the cavity. The use of Gd-DTPA improved demarcation of the tumour from the syrinx in all cases. Widening of the spinal canal and ectopia of cerebellar tonsils was a typical finding in primary syringomyelia. MRI proved a reliable method for distinguishing between a tumour-induced syrinx and primary syringomyelia.