What Is It?

Case courtesy of Radswiki.

This is an axial FLAIR MRI sequence of a third ventricle colloid cyst. These cysts are benign in nature, however they can quickly cause a deadly hydrocephalus by blocking the foramina of Monro and CSF flow out of the lateral ventricles. The hydrocephalus, or ballooning, of the lateral ventricles can cause herniation of the medial temporal lobes across the tentoirum cerebelli, and eventually herniation of the brainstem through the foramen magnum, resulting in death. Treatment includes placement of an external ventricular drain (“EVD”) in the lateral ventricle to relieve hydrocephalic pressure on the brain, followed by endoscopic surgical removal of the colloid cyst.