Female, 35 years old, with Chiari malformation. Postoperative findings are seen compatible with Chiari decompression. A suboccipital craniectomy and resection of the posterior arch of C1 have been performed. A small fluid collection is seen within the posterior operative soft tissues along with some bubbles of air.The caliber of the foramen magnum has been expanded. The cerebellar tonsils demonstrate changes likely related to cautery. The CSF space at the foramen magnum does, however, remain narrow, and on CSF flow imaging, minimal if any flow related signal is seen at this level. Outside of the posterior fossa, no areas of significant parenchymal signal abnormality are seen. No edema or mass effect is detected. The lateral ventricles remains slightly prominent but this finding is unchanged.
Findings are seen compatible with recent Chiari decompressive surgery. A small fluid collection in the posterior soft tissue operative bed could represent a small pseudomeningocele or possibly just a seroma. The foramen magnum has been expanded, though the CSF space remains narrowed and there is no significant CSF flow through this level. A repeat imaging after the resolution of postoperative edema will likely provide a better assessment of the decompression.