Abstracts

Anterior temporal lobe resection (ATLR) benefits many patients with refractory temporal lobe epilepsy (TLE) but may be complicated by material specific memory impairments, typically of verbal memory following left ATLR and non-verbal memory following right ATLR. Preoperative neuropsychology and structural MRI are currently used as predictors of memory deficits. Preoperative functional MRI (fMRI) of memory encoding has the potential to be of additional value., We report 15 patients with unilateral TLE undergoing ATLR; 7 had left TLE and 8 right TLE. Patients performed an fMRI memory paradigm which examined the encoding of words, pictures and faces, allowing verbal and non-verbal memory encoding to be tested in a single scanning session. This task had previously demonstrated a material-specific lateralization of encoding in the medial temporal lobes (MTL) of healthy control subjects., Individual patients with relatively greater ipsilateral compared to contralateral MTL activation had greater memory decline following ATLR. Further, activation within the ipsilateral, to-be-resected hippocampus alone was predictive of postoperative memory change whereas activation in the contralateral hippocampus was not. This was the case both in left TLE patients in whom greater left hippocampal activation for word encoding correlated significantly with increased verbal memory decline following left ATLR, and in right TLE patients in whom greater right hippocampal activation for picture encoding correlated significantly with increased non-verbal memory decline following right ATLR. In both cases no correlation was observed for the contralateral hippocampus., These findings suggest that preoperative memory fMRI may be a useful non-invasive predictor of post-operative memory change following ATLR and provide support for the functional adequacy theory of hippocampal function.[figure1], (Supported by Wellcone Trust Programme Grant (RP, MS) and the National Society for Epilepsy (MJK, JD).)