The four of the non-hydroocephalus postmortem patients had complex cardiac malformation and other visceral anomalies. Nine of the 12 clinical examined patients had normal intellegence; in addition, 40 percent had either focal neurological deficits or gait abnormalities, and 60 percent had abnormal EEGs.
The NINDS notes that when more abnormalities occur in the brain along with Dandy-Walker syndrome, the shorter the patient's life span. Treatment is focused on the patient's particular problems, with excess fluid drainage being the hallmark treatment method; this reduces intracranial pressure and swelling. If treated early, intellectual development may not be as affected.