Abstracts

Rationale: Neuroimaging studies suggest that a history of depression and seizures are associated with reduced metabolic activity in the frontal lobes and the hippocampus in persons with temporal lobe epilepsy (TLE).Methods: We investigated if depression or anxiety is related to asymmetric lateralization of hypo-metabolism in the frontal lobes, temporal lobes, hippocampus, precuneus and amygdala. We reviewed retrospective ictal and inter-ictal SPECT imaging studies in 24 consecutive patients undergoing pre-surgical evaluation for medication refractory TLE. We also reviewed inter-ictal PET imaging in 33 consecutive patients with TLE who were also undergoing pre-surgical evaluation. Clinical neurological assessment also included history, medications for mood and anxiety in TLE that was assessed at each neurological visit.Results: Ictal SPECT studies in patients with TLE, unipolar depression and anxiety showed bilateral frontal lobe hypo-metabolism. Inter-ictal SPECT studies in patients with TLE alone and TLE with comorbid depression and anxiety showed bilateral frontal and temporal lobe hypo-metabolism. Inter-ictal PET studies showed asymmetric hyper-metabolism in the right frontal and left temporal lobes for all patients with TLE, independent of comorbid anxiety and depression and bilateral hypo-metabolism in the hippocampus.Conclusions: Collectively, these findings suggest severe asymmetric dysfunction in all persons with TLE regardless of comorbid anxiety or depression with more severe asymmetric dysfunction in the right frontal and left temporal lobes. We anticipated asymmetric dysfunction in the left hippocampi; however, the pathway of asymmetric dysfunction was in the right frontal lobe and left temporal lobe with bilateral dysfunction in the hippocampus.