Generalised cerebral atrophy following temporal lobectomy for intractable epilepsy associated with mesial temporal sclerosis

Studies of post-operative imaging data have mainly concentrated on brain atrophy following radiotherapy and/or chemotherapy. We have investigated the effect of conventional surgery on the unresected brain tissue based on the comparison of magnetic resonance images acquired pre- and post-operatively in 13 subjects with a history of mesio–temporal epilepsy. The pre- and post-operative scans were co-registered prior to volumetric analysis. The total brain volume (TBV) was calculated by semi-automated segmentation, and the total volume loss was the difference between the post-operative and pre-operative TBV. The total volume of resection was determined by manual delineation in the post-operative scan. The atrophy volume in the post-operative scan was calculated as the difference between the total volume loss and the resection volume. In 6 cases, there was generalised cerebral atrophy of the order 4–5% of the total brain volume. In addition to the automated volumetric technique, the images were assessed by two expert neuroradiologists. There was complete correspondence between their assessment and the automated technique. The causes and significance of this phenomenon are unknown but it requires further investigation as it may be related to seizure control and neuropsychological changes following epilepsy surgery.