Brainstem gliomas typically present with cranial nerve abnormalities, pyramidal tract signs, or cerebellar dysfunction. Most commonly, these astrocytomas arise in the pons and are moderately aggressive. Lesions may be exophytic, but typically will circumferentially enlarge the brainstem. MRI imaging tends to demonstrate high signal on T2 with rare enhancement. A cystic component may be present in 10% of cases. If large enough the fourth ventricle will be displaced posteriorly from the lesion.