Abstracts

Rationale: Postictal psychosis (PIP) is a disorder in which patients with epilepsy experience psychotic symptoms following a seizure or seizure cluster. This clinically important problem offers a unique neurological perspective as it shares qualities from schizophrenic psychosis, such as the positive symptoms of paranoia and hallucinations. A recent case-controlled study of risk factors for PIP identified four primary factors: extratemporal/ambiguous ictal localizations, family history of neuropsychiatric illness, a history of encephalitis and abnormal EEG findings interictally (Alper, et al. 2008). First episode schizophrenia is associated with reduced hippocampal and whole brain volume and auditory hallucinations in schizophrenic patients are associated with reduced superior temporal gyrus volume (Barta, et al. 1990). The neuroimaging correlates of PIP remain poorly defined. Quantitative MRI analysis in patients with PIP may better characterize the neurological abnormalities underlying this disorder and psychosis in general. We hypothesize that analysis of cortical thickness and the volume of subcortical structures will reveal specific neuro-anatomical abnormities unique to PIP patients. Methods: T1-weigthed MRIs optimized for gray-white matter contrast were obtained for 11 epilepsy patients with PIP, 11 epilepsy patients without PIP (EPI), and 11 age and gender matched normal controls (NC). PIP patients were matched with EPI patients in age, gender, age of onset, seizure type and lateralization of seizure focus. Cortical surface reconstruction, subcortical segmentation, and group registration and averaging were performed by Freesurfer to compare the volume of various subcortical structures, as well as vertex-wise comparison of cortical thickness between groups. Results: The mean age of the PIP group was 39.1 years (median: 37.3, range 19 to 59); the mean age of the NC group was 38.2 years (median: 33, range 19 to 58). Auditory hallucinations were reported in 45% of the PIP group. Initial analysis reveals focal areas of cortical thinning in the left superior temporal and fronto-temporal regions of PIP patients when compared to NC. Furthermore, no differences were observed in the volume of subcortical structures. Conclusions: Quantitative analysis of cortical and subcortical regions identified thinning within the superior temporal gyrus in patients with PIP, similar to findings in schizophrenic patients with auditory hallucinations.