Syringomyelia associated with a foramen magnum meningioma.

In a 14-year-old boy with a meningioma at the foramen magnum extending to C-2, cervical syringomyelia was found on metrizamide computed tomographic myelography. The mechanism of syrinx enhancement on delayed computed tomographic scanning was considered to be due to transneural passage of metrizamide into the spinal cord. Long-standing spinal block may be responsible for development of syringomyelia. Syringomyelia associated with spinal extramedullary tumors was reviewed in the literature.