Abstracts

Rationale: Association between psychosis and epilepsy in particular the episodic interictal psychosis has always interested psychiatrists and neurologists. Epilepsy may present as non-convulsive behavioral problems and psychosis mimicking schizophrenia. Acute psychosis has long been recognized as a complication of chronic refractory epilepsy. However, there are no standard criteria based on semiology or psychopathology to distinguish epileptic from nonepileptic psychoses. It is not clear if obtaining EEG should be part of the evaluation of patients with psychosis or altered behavior.Methods: We reviewed the EEG and clinical data of 409 adult patients presenting with acute psychosis or altered behavior from 2001-2006, to assess the diagnostic value of EEG in the evaluation of patients with this condition. All of these patients were referred by psychiatrists in an academic hospital. After excluding patients with acute medical conditions 307 patients, 154 female (18-81 year, 40.1±15.1), and 153 male (18-79 year, 37.5±13), were included in this study. The diagnoses included acute behavioral change or psychosis with or without prior diagnosis of one or more underlying psychiatric condition such as schizophrenia, bipolar disorder, depression, anxiety, substance abuse, and mood disorder. The EEG was obtained within the first week of presentation and in most cases within 48 hours. All patients were taking multiple medications for their psychiatric and medical conditions at the time the EEG was obtained. Results: Among female patients 22/154 (14%) had abnormal EEG consisting of posterior background- or diffuse slowing (n=20, 91%), and focal slowing on the left (n=2, 9%). Diffuse slowing was considered a non-specific sign of encephalopathy related to either an underlying brain disease or medication effect. Both patients with focal abnormalities had normal brain imaging. The EEG abnormalities were more common (77%) in the age group>40 yeas (p<0.02). Among male patients 14/153 (9%) had abnormal EEG consisting of diffuse slowing (n=5, 38%), focal slowing all on the left (n=8, 57%), and bilateral temporal spikes (n=1, 7%). The incidence of left-sided focal slowing was significantly higher in men (p<0.02), while there was significantly higher incidence of diffuse slowing in women (p<0.004). Conclusions: These findings suggest that the incidence of temporal lobe epilepsy presenting as acute behavioral changes seem to be low. Therefore, routine EEG may have a limited role as a screening tool for this purpose in the evaluation of patients with acute psychosis or altered behavior. However, our findings might have been affected by the fact that the EEG studies were done after the clinical condition was relatively controlled with medication. A major finding of our study is that focal slowing on EEG in patients with acute psychosis particularly men occurred only on the left while diffuse slowing was more common in women particularly those >