Arachnoid cyst as the cause of bipolar affective disorder: case report.

This report presents the course of diagnostic examinations and treatment of a 20-year-old man with bipolar affective disorder for which an organic basis was demonstrated. Computed tomography of the brain revealed an arachnoid cyst that was surgically treated. The patient underwent both psychiatric and neurosurgical treatment. After two-year follow-up and medicamentous treatment prescribed, the patient was symptom-free requiring no psychopharmacotherapy for the next 5.5 years. His overall life functioning is normal, with no signs of disease.