Clinical correlates of septum pellucidum cavities: an unusual association with psychosis.

Cavities in the septum pellucidum are widely regarded as incidental findings of little clinical importance. The prevalence of such cava on computerized tomography in a mixed sample of 22000 neurological and psychiatric patients is found to be 0.15%. A statistical association between this anomaly and a referral diagnosis of functional psychosis is reported, and 6 cases are described. These cases were male and characterized by an early history of developmental delay, with lifelong disturbances of emotion and behaviour prior to the onset in early adulthood of an atypical schizophrenia-like psychosis with disorders of speech and movement. It is suggested that septal cavities may signal an underlying abnormality of function relevant to the pathogenesis of these illnesses.