Empyema of the cavum septum pellucidum.

The cavum septum pellucidum is not a part of the brain's ventricular system and does not communicate with the lateral ventricles. However, under conditions of increased intraventricular pressure, cerebrospinal fluid may penetrate the septum and cause formation of a cavity. We report a neonate with pus accumulation in the cavum septum pellucidum after an episode of ventriculitis. The cavum septum pellucidum disappeared after medical and surgical management of the infection and increased intracranial pressure.