Isolated parts of the ventricular system.

It has been known for years that patients with shunted hydrocephalus can develop an isolated fourth ventricle with or without signs of cerebellar dysfunction. It has also been reported about other isolated parts of the ventricular system following treatment of communicating hydrocephalus. We observed three children, two with an isolated fourth ventricle and one with an isolated third ventricle. The clinical appearance, the pathogenesis and treatment will be discussed.