[Cerebellar cyst--a variant of the isolated fourth ventricle]

Two cases of cerebellar cyst showing mass effect were presented as a treatable clinical entity not fully mentioned before. Analysis of the clinical data including follow-up computerized tomographic findings suggested its pathogenetical relationship to cerebellar porencephalic cyst following perinatal distress, and also, similarity to isolated fourth ventricle which would be encountered more frequently with the advent of computerized tomography in perinatal care. The authors stressed the importance of early surgery during infancy as an effective therapeutic measure.