Diffusion tensor imaging findings and their correlation with neuropsychological deficits in patients with temporal lobe epilepsy and interictal psychosis

Purpose: To examine frontotemporal white-matter integrity in patients with temporal lobe epilepsy (TLE) and interictal psychosis. Method: Patients with TLE and interictal psychosis (IP; n = 20) were compared with age-matched TLE patients without psychosis (NIP; n = 20). Patients had either no focal lesions or hippocampal sclerosis on conventional MRI. Complete diffusion tensor imaging (DTI) data were available in 18 IP and 20 NIP patients. A region-of-interest (ROI) approach was used to determine the DTI measures, fractional anisotropy (FA) and mean diffusivity (MD), in the middle frontal and middle temporal gyri. The relation between the DTI measures and neuropsychological tests previously identified as impaired in the IP group was examined. Results: The IP group had significantly lower FA values in both frontal and temporal regions and significantly higher MD in bilateral frontal regions. We found that performance on some neuropsychological tests was significantly related to frontotemporal FA reductions. Conclusions: Our findings suggest that subtle abnormalities in the frontotemporal white matter of patients with interictal psychosis may be undetectable on conventional MRI. These abnormalities may contribute to the cognitive deficits detected in these patients.