Postoperative headache, history of Chiari decompression on 4/28/2015 Again seen are postsurgical changes of Chiari decompression including suboccipital craniectomy and removal of posterior arch of C1. There is also evidence of tonsillar debulking with T2 hyperintensity and enhancement involving the cerebellar tonsils, which shows evolution. Residual tonsils are again seen extending to the C2 level, lower on the left than the right. Again seen is retroversion of the dens which indents the cervicomedullary junction ventrally. There remains diminished CSF spaces ventrally and dorsally at the foramen magnum although significantly improved dorsally at the C1 and C2 levels compared to the preoperative study particularly in the midline. CSF flow sequence demonstrates some, although diminished, biphasic flow at the foramen magnum anteriorly and posteriorly.This small fluid collection in the posterior soft tissues measuring 1.5 x 2.7 cm in the axial plane and up to 2.5 cm in the craniocaudal dimension and consistent with a small pseudomeningocele similar to prior.There is no evidence for ventriculomegaly. No evidence of acute infarct, intracranial hemorrhage, or new intracranial mass or mass effect. Major flow voids are preserved. Mild mucosal thickening is seen in the paranasal sinuses. Minimal mastoid air cell fluid.
1. Evolution of postsurgical changes related to recent Chiari I decompression including tonsillar debulking. There remains diminished CSF spaces ventrally as well as dorsally at the foramen magnum, although significantly improved dorsally at the C1 and C2 levels compared to the preoperative study--particularly in the midline. CSF flow sequence demonstrates some, although diminished, biphasic flow at the foramen magnum anteriorly and posteriorly.2. Unchanged ventricular size without hydrocephalus.3. Small fluid collection, likely representing a pseudomeningocele, in the dorsal upper cervical paraspinous soft tissues.