 Again seen are postoperative changes related to resection of a left frontal periventricular lesion. Postsurgical changes of left-sided subdural shunt catheter placement are also again seen. Catheter tip is within the left-sided subdural collection. Compared to most recent CT from 5/2/2016, subdural collections are similar measuring approximately 9 mm on the right and 18 mm on the left, but decreased since prior MRI from 4/4/2016. The ventricular system is decreased since CT dated 5/2/2016, for example the lateral ventricles measure 29 mm in the transverse dimension, previously approximately 51 mm. Third and fourth ventricles have also significantly decreased in size in the interval. Blood products in the posterior aspect of the lateral ventricles are again seen with signal abnormality on the current study which may be related to chronic dependent blood products, although more acute blood products are not definitively excluded. There are no findings to definitively suggest new hemorrhage. Extensive low T2 signal throughout the surface of the brain with susceptibility effect most compatible with superficial siderosis is again noted and not grossly increased in the interval since prior MRI from 4/4/2016. Note there is extensive artifact related to the subdural shunt with limits evaluation on the susceptibility weighted sequence.Interval decrease in periventricular T2 hyperintensity is noted since prior MRI likely reflecting improvement in hydrocephalus with decrease in transependymal flow. Mild apparent diffusion restriction along the right lateral ventricle margin may be related to blood products.Additional findings including bilateral frontal porencephaly and communication of the CSF spaces with the extra-axial collections are again noted. Extra-axial CSF collection/arachnoid cysts in the posterior fossa are not significantly changed. No significant midline shift or herniation. Major vascular flow voids are preserved. Maxillary sinus mucus retention cysts again seen.
1. Extensive supra- and infratentorial superficial siderosis is again seen and may explain hearing loss. No findings to suggest worsening siderosis or new hemorrhage since prior.2. Bifrontal porencephaly with CSF spaces communicating with subdural collections again seen. There is interval decrease in ventriculomegaly compared to most recent CT from 5/2/2016. Bilateral subdural collections are similar to most recent CT 5/2/2016 and decreased since MRI 4/4/2016.