Persisting intraventricular fat-fluid levels following surgery on a ruptured dermoid cyst of the posterior fossa.

Intracranial dermoid cysts occasionally rupture spontaneously into the ventricles or into the subarachnoid space. In such cases, intraventricular fat-fluid levels are invariably evident at computed tomography and may even be visible on a conventional radiograph of the skull. A case is described in which fat was observed to remain in the ventricles long after surgical removal of a dermoid cyst. We think that this fat, by causing obstruction of the cerebrospinal fluid pathways, should be regarded as a potential cause of intermittent elevation of intracranial pressure.