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. The isolation was presumably due to granulomatous inflammation of the ependyma surrounding the fourth ventricular outlets. The isolated fourth ventricle was responsible for a deterioration of neurological status. Neurosarcoidosis is a severe complication in sarcoidosis patients. An isolated enlargement of the fourth ventricle is a rare complication in clinically deteriorated patients with neurosarcoidosis and ventricular drainage, which may require neurosurgical treatment.