Clinical question: Reason for for ventricular obstruction and herniation, evaluate for CSF leak. Pre- and post enhanced brain MRI:Diffusion weighted images are negative.Images through the supratentorial space demonstrate paucity of cortical sulci, small size of supratentorial ventricular system however with maintained midline, crowding and effacement of the basal cistern as well as evidence of minimal transtentorial herniation of left temporal lobe (coronal T2 series 1/1/2001 image 20). There is no detectable signal abnormality of supratentorial brain parenchyma.Images through posterior fossa demonstrate interval resolution of extensive previously seen edema of the inferior cerebellar hemispheres since prior MRI exam from 7-2-15 and with evolution of bilateral small foci of encephalomalacia of the cerebellum (R>L). Similar to prior exam the 14th ventricle is a small however in midline. There is postoperative changes of Chiari decompression with prolapse of the cerebellum into the expanded space and near complete absence of subarachnoid space in the posterior fossa and at the level of the compression. This appearance is similar to prior exam.Post enhanced images demonstrate no abnormal enhancement of brain parenchyma or the leptomeninges. Mild dural enhancement at the surgical site is within expected postoperative finding. There is no evidence of CSF from the fundus exam as is questioned clinically.Pre- and post enhanced cervical spine MRI:Examination demonstrates post operative changes of Chiari decompression. There is inferior prolapse of the cerebellum inferiorly with resultant near complete effacement of CSF space at the level of Chiari decompression. Small foci of encephalomalacia (R>L) in inferior bilateral cerebellum at the site of previously noted acute strokes are identified. The signal intensity and caliber of cervical cord is within normal.Post contrast images demonstrate no detectable abnormal enhancement of the cord or the pia-meninges. The expected epidural enhancement of the cervical region appears more pronounced and could represent engorgement/increased pressure.There is no evidence of CSF leak on this study.Pre and post enhanced MRV:Examination demonstrates normal appearing are intracranial venous sinuses and without evidence of abnormality. There is also normal visualization of bilateral internal cerebral veins, vein of Galen and straight sinus. Inferior sagittal sinus is also identified and unremarkable. Bilateral cavernous sinuses and bilateral inferior petrosal veins are detected. There is increased size and enhancement of the visualized upper cervical epidural venous plexus which could represent increased pressure. There is no detectable abnormality of cerebral cortical venous structures
1.Nonenhanced brain MRI demonstrate no evidence of restricted diffusion. There is a significant paucity of cortical sulci, slitlike ventricular system, effacement of basal cisterns and minimal transtentorial herniation of the left cerebellum. Prolapse of cerebellum into the expanded subarachnoid space at the level of Chiari decompression with resultant complete effacement of the CSF space and with small size of fourth ventricle. Findings are believed to be secondary to decreased intracranial pressure. This appearance is not significantly different than prior head CT examination from 9-8-15. Interval evolution of regions of bilateral inferior cerebellar acute strokes to small foci of encephalomalacia as detailed. No detectable abnormal enhancement.2.Pre and post enhanced MRI of cervical spine demonstrate prolapse of the cerebellum into the subarachnoid space at the level of Chiari decompression and with resultant complete effacement of subarachnoid space. Normal signal intensity and caliber of the cord. No detectable abnormal enhancement. The epidural venous plexus is prominent.3.MRV of intracranial circulation demonstrates normal appearing all intracranial venous sinuses, deep venous structures and the cerebral cortical veins. There is robust visualization of prominent visualized upper cervical epidural venous plexus which conceivably could represent increased venous pressure.