Isolated posterior fossa hypertension and brainstem compression caused by entrapped Dandy-Walker cyst: a case report.

Lateral ventricular shunting alone is often considered to be adequate treatment for hydrocephalus caused by Dandy-Walker syndrome. A patient is presented in whom progressive spastic tetraparesis and signs of severe brainstem compression developed due to an entrapped posterior fossa cysts, in spite of an adequately functioning lateral ventricular shunt. Addition of a cystoperitoneal shunt resulted in rapid resolution of symptoms and deficits. This case illustrates that potentially fatal brainstem compression and dangerous posterior fossa hypertension may develop if the posterior fossa cyst does not communicate with the lateral ventricles, where the shunt is placed.