Fourth ventriculoceles with extracranial extension.

The radiographic features and long-term clinical outcome in three patients who presented at birth with a cystic suboccipital mass in direct communication with the fourth ventricle are reviewed. The pathological findings in a fourth infant who died are also discussed. All surviving infants were treated with cyst excision and diversion of cerebrospinal fluid. The prognosis in these children, followed from 6 to 20 years, surpasses that of the more common occipital encephalocele, for which this entity could be mistaken. The morphogenetic implications relative to more common congenital lesions in this location are discussed.