Refractory psychosis and prominent cognitive deficits in a patient with mega-cisterna magna.

We present a case of refractory psychosis with prominent cognitive deficits in a patient with 'mega-cisterna magna', a congenital defect within the 'Dandy-Walker Complex' continuum. The 21-year-old female had a 3-year history of refractory psychotic symptoms despite adequate antipsychotic treatment. CT and MRI scans disclosed 'mega-cisterna magna'. Thorough neuropsychological testing recorded extensive deficits. Treatment with amisulpride 1200 mg/day resulted in a 30% decrease in PANSS score within 2 months. Then galantamine 8 mg/day was added and PANSS score decreased further by 27% within 2 weeks. Cognitive and social functioning was overall much improved. The effect was sustained in a 24 months follow-up. It is postulated that even a less extended cerebellar lesion, such as mega-cisterna magna, can be associated with psychosis, and in some cases with treatment refractoriness or cognitive dysfunction. Adjuvant galantamine may improve cognitive and psychosocial functioning in these patients.