Personality disorders improved after arachnoid cyst neurosurgery, then rediagnosed as 'minor' organic personality disorders.

The prevalence of arachnoid cysts (AC) is considerably increased in psychiatric patients, suggesting a possible causal relationship between AC and certain psychiatric disorders. Neurosurgery of AC in psychiatric disorders is, however, not recommended if no accompanying neurological symptoms or signs of increased intracranial pressure are present. In two cases of slow onset personality disorder in persons suffering from so-called asymptomatic AC, we performed AC neurosurgery beyond established rules. Both comparisons before and after neurosurgery of psychopathology and the following long-term course support in retrospect that both cases might be re-diagnosed as having suffered from 'minor' organic personality disorders before AC neurosurgery, which improved thereafter. The two cases did not initially appear to fulfill the established criteria for organic personality disorders either according to ICD-10 or DSM-IV, but in retrospect satisfied most criteria. In themselves, the personality disorders appeared not very severe, but had considerable relevance for the patients' lives. The established rules for AC neurosurgery should be reconsidered at least when therapy-resistant psychiatric disorders are observed in AC sufferers.