Juvenile pilocytic astrocytoma status post resection and induction chemotherapy. There are post-treatment findings in the posterior fossa. The tumor arising from the right cerebellar hemisphere and brainstem with encasement of the basilar artery and right 7th and 8th cranial nerves appears to have slightly decreased in size, measuring 21 x 34 mm, previously 24 x 36 mm. There is no evidence of acute infarct. There is a right transparietal ventriculostomy catheter in unchanged in position. However, the lateral ventricles appear to be slightly smaller in size, now virtually collapsed. The other portions of the ventricular system appear to be unchanged. There is no midline shift or herniation. The major cerebral flow voids are intact. The orbits, skull, paranasal sinuses, and scalp soft tissues appear unchanged.
Apparent slight interval decrease in size of the treated posterior fossa juvenile pilocystic astrocytoma.