s/p chiari decompression. dizziness with CT evidence of fluid collection on suboccipital craniotomy site. No evidence of acute ischemic or hemorrhagic lesion.There is evidence of bilateral suboccipital craniectomy and about 21mm x 49mm x 36mm sized CSF like fluid collection on the suboccipital craniotomy site without evidence of restricted diffusion but with minimal peripheral enhancement. This may indicated postoperative uncomplicated fluid collections on operation site.Ovoid shaped thin rim type of enhancement on bilateral tonsils on Gad enhanced images (best seen on series 1502, image 123/200) without evidence of surrounding edema may indicate post operative changes or due to Chiari malformation, Correlation with pre operative exam is recommended.CSF flow study using Phase contrast MRA technique shows pulsatile craniocaudal flow through anterior aspect of the foramen magnum and inferior aspect of cerebellar tonsil.Delineation of inferior vermis is not possible with bilateral cerebellar hemispheric interdigitation especially inferior aspect and partial continuity of cerebellar white matter tracks indicating possible partial vermian hypoplasia or partial rhombencephalosynapsis.The ventricles, sulci and cisterns are symmetric and unremarkable. The midline structures and cranial-cervical junction are normal. Normal flow voids are identified in the major intracranial vessels. The paranasal sinuses and are clear.Partial opacifications on bilateral mastoid air cells.
1. No evidence of acute ischemic or hemorrhagic lesion.2. Fluid collections on bilateral suboccipital craniectomy sites without evidence of complication.3. Maintained craniocaudal pulsatile CSF flow anterior aspect of foramen magnum. Craniocaudal CSF flow was shown on the posterior aspect in particular inferior to cerebellar tonsil but the magnitude is less than that of anterior aspect CSF flow.4. Partial rhombencephalosynapsis or partial vermian hypoplasia as described above.