Fig 3.

Pre- and posttreatment MR imaging from patient 2. Dashed line indicates the foramen magnum. A, Pretreatment MR image demonstrates cerebellar tonsillar ectopia (arrow). The dashed line indicates the plane of the foramen magnum. Midline sagging of the brain with inferior displacement of the mammillary bodies is seen. In this patient, there was no abnormal dural enhancement on pretreatment MR imaging (not shown). B, Follow-up brain MR image after CT-guided blood patching demonstrates resolution of the cerebellar tonsillar ectopia and midline sag.