Mega cisterna magna in bipolar mood disorder: a case report.

Mega cisterna magna (MCM), one of the members of the Dandy-Walker complex, is a developmental malformation of the posterior fossa that is larger than 10 mm but morphologically does not affect the vermis and cerebellar hemispheres. Reports of psychiatric disorders associated with this anomaly are rare. We present the case of a patient with MCM who presented with a psychotic manic attack and was diagnosed with bipolar disorder.