Walsh & Hoyt: Tumors of the Fourth Ventricle

The fourth ventricle is a broad, tent-shaped, midline cavity located between the cerebellum and the brain stem. Rostrally, it is continuous with the cerebral aqueduct, and caudally, it is continuous with the central canal of the medulla. It communicates directly with the subarachnoid space via the foramina of Luschka laterally and the foramen of Magendie medially and caudally. Tumors such as astrocytomas and medulloblastomas that arise within the substance of the cerebellum and eventually extend into the fourth ventricle are more common than are tumors that originate within the ventricle. The most common tumors that arise within the fourth ventricle are ependymomas (more common in children) and choroid plexus papillomas (more common in adults). Other tumors that occur within the fourth ventricle are epidermoids and, rarely, meningiomas, schwannomas, colloid cysts, cavernous angiomas, and hemangioma calcificans.