Adult diagnosed Dandy Walker malformation presenting as an acute brainstem event--a case report and review of the literature.

The Dandy Walker Malformation (DWM) is an infrequent condition seen in pediatric patients. Adult presentation of DWM is extremely rare. This condition usually presents in childhood with hydrocephalus and cerebellar signs and symptoms. This case describes a woman with an undiagnosed DWM who was asymptomatic until the age of 56 when she developed the acute onset of headache, nausea, vomiting, and diplopia. Her history and physical exam were consistent with an acute brainstem infarct. MRI revealed the underlying malformation. The clinical and radiological findings are discussed as well as their implications and possible etiologies.