Abstracts

RATIONALE: Standardized memory tests involving the learning and recall of verbal and non verbal material are commonly used in the presurgical investigation of mesial temporal lobe epilepsy (MTLE). Such tests provide indications of laterality when a specific deficit is evidenced. As interictal tests are often normal, it has been proposed to assess memory in post ictal period to improve focus localization. In order to precise the advantage of postictal tests we have compared interictal and post ictal neuropsychological examinations in 20 patients with MTLE. METHODS: All patients had MTLE with well defined laterality and were right handed. Similar tests were used to study fluence, learning and recall during interictal period and 20 mn after partial seizure onset only when the patient was able to understand and realise them correctly. Interictal and postictal tests were performed during a continuous monitoring video-EEG in phase 1 presurgical examination using surface and sphenoidal electrodes. Laterality of MTLE was validated by post surgical outcome. RESULTS: All patients with right MTLE had normal interictal tests without memory deficit. The postictal tests showed : (1) learning difficulties and low score of visual spatial recall, (2) no difficulty for verbal learning but a little impairment of the verbally-learned item recall. Forty-five per cent of left MTLE had a deficit of verbal memory in interictal period. In post ictal examination an important deficit of recall of verbal items was observed while learning was similar to the interictal score. This deficit appeared in all the patients , with or without deficit in interictal period. CONCLUSIONS: Post ictal neuropsychological examination is more sensitive than interictal examination. A specific memory deficit was found in all cases. In patients with right MTLE, this deficit is onvolved visuo-spatial memory both for learning and recall. In patient with left MTLE the deficit predominantly involves the recall of verbally-learned items. Such results suggest the usefulness of post ictal neuropsychological evaluation to predict MTLE laterality.