History of craniotomy for Chiari malformation. There are postsurgical changes of a suboccipital craniectomy and C1 laminectomy for decompression. The CSF spaces at the ventral and dorsal foramen magnum remain widely patent. Again seen is a retrocerebellar CSF intensity collection, not significant changed in size. CSF flow sequence demonstrates biphasic flow at the foramen magnum as well as some continuity of flow at the dorsal foramen magnum into the retrocerebellar CSF space. There is no evidence of intracranial hemorrhage, mass, or acute infarct. There are a few punctate foci of increased T2/FLAIR signal within the periventricular white matter which are nonspecific but not significantly changed when accounting for differences in technique. There is no abnormal intracranial enhancement. The ventricles and basal cisterns are normal in size and configuration. There is no midline shift or herniation. The major cerebral flow voids are intact. There is minimal patchy mucosal thickening within the paranasal sinuses. The orbits, skull, and scalp soft tissues are grossly unremarkable.
1. Post-surgical changes of suboccipital craniectomy and C1 laminectomy for Chiari decompression .2. Biophysical CSF flow at the foramen magnum which appears to communicate with the prominent retrocerebellar CSF space, not significantly changed in appearance.