Delayed metrizamide CT enhancement of syringomyelia: postoperative observations.

Delayed metrizamide computed tomography (CT) was performed both preoperatively and postoperatively in 11 syringomyelia patients. Change of syrinx size between the studies was easily assessed on CT. The morphologic change of the syrinx gave useful information about its continuity. One of our cases had reoperation as a result of this CT information. All cases with Chiari I malformation still showed filling of the syrinx cavity by metrizamide after posterior fossa decompression and obex plugging. This supports the idea that the abnormal fluid circulation maintaining syringomyelic cavities is more than just the flow through the obex to the central canal but may also be from fluid passage through the cord substance.