An isolated fourth ventricle in neurosarcoidosis: MRI findings.

We report on an isolated enlargement of the fourth ventricle in a patient with neurosarcoidosis which developed 3 years after the insertion of a ventriculo-atrial shunt. Repeated MRI images were obtained in a patient with known neurosarcoidosis between 1995 and 2000. Imaging findings were correlated to the medical course of the patient, who developed a hydrocephalus and a trapped fourth ventricle consecutively.