Status post craniotomy for posterior fossa tumor resection. Evaluate for residual posterior fossa tumor and hemorrhage. Postsurgical changes of a suboccipital craniotomy for resection of a large fourth ventricular tumor. There are small areas of restricted diffusion along the surgical cavity margins within the dorsal brainstem and the cerebellum indicating cytotoxic edema. Minimal enhancement is noted at the periphery of the surgical bed but there is no convincing evidence of residual tumor. There is small amount of susceptibility abnormality located at the perimeter of the resection cavity indicating blood products. There is also a small amount of blood products in the dependent portions of the occipital horns of the lateral ventricles bilaterally. There has been interval reduction in the size of the supratentorial ventriculomegaly and there is a right posterior parietal approach ventriculostomy catheter which terminates in the body of the right lateral ventricle after entering the posterior horn of the right lateral ventricles. There are foci of left greater than right air within the nondependent portions of the anterior horns of the lateral ventricles which are most likely postprocedural. Additional foci of pneumocephalus are visualized anterior to the frontal lobes but this causes only minimal adjacent mass effect. There is no midline shift or herniation. The major cerebral flow voids are intact. The orbits, skull, paranasal sinuses, and scalp soft tissues are grossly unremarkable.
1.Expected postsurgical changes of resection of a large posterior fossa tumor. No convincing evidence of residual tumor.2.Minimal areas of restricted diffusion along the surgical cavity margins along the dorsal brainstem and cerebellum are compatible with cytotoxic edema.3.A right parietal approach ventricular catheter terminates in the body of the right lateral ventricle. There is interval reduction in the size of the ventricles.