Cyst and hydrocephalus: possible shunt malfunction. There is a catheter that enters via a right occipital burr hole and terminates in the anterior right lateral ventricle. There are thin septations within the dilated portion of the posterior right lateral ventricle, which has not significantly changed in size. The rest of the ventricular system is not particularly enlarged. There is confluent high T2 signal in the right frontal, parietal, and occipital white matter surrounding dilated right lateral ventricle, along with volume loss. There are also other scattered areas of periventricular and subcortical white matter T2 hyperattenuation. There is no evidence of acute infarction or intracranial hemorrhage. There are postoperative findings related to posterior fossa decompression with diminished flow of cerebrospinal fluid across the craniocervical junction. The cerebellum is not low-lying, however. There is an extra-axial catheter in the right frontoparietal convexity. There is no midline shift. The pituitary gland is normal in size. There is no abnormal intracranial enhancement. The major cerebral flow voids are intact. The orbits and paranasal sinuses are grossly unremarkable.
1. Dilatation of posterior portion of the shunted right lateral ventricle with septations, which may represent adhesions with loculation or cyst formation and surrounding encephalomalacia and gliosis. The constellation of findings may be the result of remote insult, such as infection and perhaps ischemia. Other scattered areas of periventricular and subcortical white matter T2 hyperattenuation may represent chronic small vessel ischemic disease, but no evidence of acute infarct. 2. Postoperative findings related to posterior fossa decompression with diminished flow of cerebrospinal fluid across the craniocervical junction. 