 Again seen is an Ommaya catheter with tip in the lateral aspect of the lateral ventricle. Again seen is a CSF signal intensity collection surrounding the catheter which is slightly larger measuring approximately 4.4 x 2.7 cm, previously 3.0 x 2.0 cm, but with near resolution of surrounding vasogenic edema. There is mild interval decrease in size of the ventricular system. Periventricular FLAIR hyperintensity which may have represented transependymal flow has also decreased.There is no discrete intracranial mass, midline shift, or herniation. Partially empty sella is again seen which can be normal variant but appears slightly less prominent than before.No abnormal mass within the orbits is appreciated. There is enhancement surrounding the optic nerve sheaths bilaterally, similar to prior. Distended optic nerve sheaths are again seen, perhaps slightly less prominent the interval. Previously seen bulging at the optic nerve head/papilledema also no longer appreciated. Evidence of left-sided intraocular lens replacement. No signal abnormality within the optic nerves. Left maxillary mucus retention cyst and minimal mucosal thickening in the ethmoid sinuses. There is heterogeneous low T1 marrow signal involving the calvarium including enhancement of the clivus which appears similar to multiple prior studies. No new osseous destruction; the finding may represent posttreatment change.CERVICAL SPINE
1. There is no evidence of progressive disease in the brain or spine. No new mass or new focus of abnormal parenchymal or meningeal enhancement. 2. There is mild decrease in size of the ventricular system compared to 9/1/2015 and decrease in periventricular FLAIR hyperintensity, findings which are favored to represent improvement in hydrocephalus with decreased transependymal CSF flow. Previously seen papilledema is also no longer evident and the partially empty sella also appears slightly less prominent; these findings are subtle but suggest improvement in intracranial hypotension and can be correlated with clinical findings. 3. CSF signal intensity fluid collection in the right frontal lobe surrounding the Ommaya catheter is slightly larger, but previously seen surrounding vasogenic edema has nearly resolved.4. There is no significant change in abnormal enhancement surrounding the optic nerve sheaths which is nonspecific and may be related to perineuritis, possibly from treatment-related change or possibly related to known leptomeningeal disease. No new nodular enhancement or mass in the orbits is appreciated to definitively suggest this represents lymphomatous involvement.5. Diffuse enhancement involving the cauda equina nerve roots remains unchanged across multiple prior studies and may represent treated leptomeningeal disease. No new nodular enhancement involving the cauda equina nerve roots or elsewhere in the spine to suggest worsening leptomeningeal disease. No epidural tumor.6. Enhancement involving the clivus as well as patchy enhancement involving the bilateral iliac bones are nonspecific but also remain unchanged across multiple prior studies.