[Psychosis associated to megacisterna magna].

Megacisterna magna is a developmental malformation of the middle-line brain structures, which exists along a continuum with cerebellum hypoplasia (Dandy-Walker variant) and cerebellum agenesia (Dandy-Walker syndrome). Psychotic disorders, and particularly schizophrenia, are now conceptualised as disorders of neurodevelopment. We report on a patient who presented a psychotic disorder (delusional type), and mega cisterna magna. This is the first report of such an association, and it is suggested that both the psychotic disorder and the mega cisterna magna may be the expression of a single underlying neurodevelopment abnormality.