Abstracts

The validation and clinical usefulness of fMRI will depend on the method[apos]s ability to predict postoperative outcome, i.e. morbidity. We aimed to investigate whether presurgical memory-fMRI is able to predict postoperative memory loss after anterior temporal lobectomy (ATL) in right sided mesial temporal lobe epilepsy (MTLE). We included 16 medically intractable MTLE patients, who had a presurgical evaluation including continuous video-EEG monitoring, an epileptogenic lesion in the right hippocampal formation proven by high-resolution MRI, and consecutive ATL. The activation condition during the memory-fMRI (1.5 T, coronal EPI, voxel dimensions 3.0x3.0x5.0 mm3) consisted of covert retrieval from long-term memory induced by self-paced performance of Roland[apos]s Hometown Walking task, an imaginative walk through the patient[apos]s hometown (Jokeit et al, Neurology 2001;57:1786-93). To perform group data analysis, two investigators blinded to clinical data counted the voxels in a predefined region of interest over both mesiotemporal areas. Outside the scanner, we evaluated visual memory retention using Rey Visual Design Learning Test preoperatively and 6 months postoperatively. We found a correlation between the preoperative asymmetry index on memory-fMRI and the change between pre- and postsurgical measures of memory retention by using the Spearman rank correlation test (R=0.71, p=0.002). Reduced activation of the mesiotemporal region ipsilateral to the epileptogenic region correlated with a favourable memory outcome after right-sided ATL. Reduced activation of the mesiotemporal region ipsilateral to the epileptogenic region correlated with favourable non-verbal memory outcome after right sided ATL. Conclusively, memory-fMRI was found to be sensitive to material-specific memory decline after right sided ATL in which the Wada test is usually inconclusive. We suggest that memory-fMRI might replace the invasive Wada test in right sided MTLE using a simple fMRI paradigm.