Delayed CT metrizamide enhancement of syringomyelia secondary to tumor

Six cases of syringomyelia associated with intramedullary tumor were examined by metrizamide myelography and delayed computed tomography. All cases showed opacification of syringomyelic cavities 7-24 hr after myelography. This finding suggests that metrizamide can pass through the cord substance from the subarachnoid space into a syrinx cavity in noncommunicating types of syringomyelia. It supports the theory of transneural passage of fluid as part of the origin of such cavities. These cases also support the thesis that, in patients with cord cavities, tumor can be excluded only if the cavity is demonstrated within all areas of cord enlargement.