Major depression in temporal lobe epilepsy with hippocampal sclerosis: clinical and imaging correlates

Purpose: Refractory temporal lobe epilepsy (TLE) is often associated with hippocampal sclerosis (HS). Patients with major depression ( MD) may also show structural abnormalities in the limbic system. Co-occurrence of TLE with HS and MD is not uncommon. We have investigated the clinical and morphological characteristics of TLE patients in relation to MD. Methods: 34 TLE patients with HS were assessed at a Comprehensive Epilepsy Programme. All relevant clinical data were obtained, including the history of antecedent events to epilepsy. MD was diagnosed based on detailed psychiatric investigation. MRI was used to measure the volume and tissue signal (T2 relaxometry) of the hippocampus and amygdala. The imaging data were expressed as a percentage of the values obtained in a series of 55 controls. Results: A history of MD was present in 15 (44%) of 34 patients. Patients with MD had a longer duration of their epilepsy (p < 0.05) and a lower frequency of antecedent events (13% with MD, 58% without MD, p, 0.05). Both groups had a similar degree of ipsilateral HS ( small hippocampal volume, increased hippocampal T2 relaxation time) and demonstrated bilateral amygdaloid atrophy. However, the contralateral amygdala showed lower signal in the presence of MD ( 97 ( 9) ms; no MD 103 ( 8) ms; ANCOVA, p = 0.02). Conclusion: The integrity of the amygdala may influence mood disturbances in TLE patients with HS, as depression was associated with a relative preservation of the contralateral amygdala. In contrast, hippocampal abnormalities were not related to the presence of depression.