Spontaneous drainage of syringomyelia. Report of two cases.

Two cases are reported of Arnold-Chiari type I malformation associated with syringomyelia, in which magnetic resonance (MR) imaging revealed spontaneous decompression of the syrinx. In one case axial MR imaging sections showed a communication between the syrinx and the spinal subarachnoid space, which supports the hypothesis that fissuring of the cord parenchyma is instrumental in the spontaneous resolution of syringomyelia. The MR imaging changes were not accompanied by variations in the patients' clinical course.