Progressive posttraumatic cystic myelopathy: neuroradiologic evaluation.
The neuroradiologic evaluation and findings in 25 symptomatic patients with surgically proven progressive posttraumatic cystic myelopathy are reviewed. To follow patients with spinal cord injury, neuroradiologic algorithms were developed to confirm and define cystic myelopathy. The algorithm used in the early and mid 1970s relied on the myelographic demonstration of a large cord for suspicion of a cyst. Review of this material found that in progressively symptomatic patients 14 of 25 proven cysts were in large cords. A more recent algorithm used computed tomographic metrizamide myelography. In nine of 11 patients studied in this fashion, the cyst filled with contrast material 2--4 hr after injection, yet it did not communicate with the subarachnoid space at subsequent surgery. The origin of the cyst fluid and mechanism of cyst demonstration with metrizamide may be associated with transneural migration of fluid. This condition must be clinically suspected and radiologically confirmed for surgical treatment (cyst-shunt procedure) if neurologic preservation of function is to be maintained.