LATERALIZATION OF THE EPILEPTOGENIC FOCUS IN TEMPORAL-LOBE EPILEPSY BY SCALP P300

The P300 is a cognitive event-related potential partially generated by the amygdala/hippocampus complex, the most common source of temporal lobe epilepsy (TLE). In order to test the hypothesis that scalp P300 a mplitude is reduced ipsilateral to the epileptogenic focus in TLE, we performed a prospective study of 15 subjects with TLE and compared the lateralizing ability of scalp P300 to interictal EEG. P300 asymmetrie s in TLE were compared with asymmetries in a control group. P300 ampli tude was significantly attenuated ipsilateral to the epileptic focus. P300 amplitude reduction correctly lateralized the focus in 82% of the cases (p = 0.02). We conclude that scalp P300 accurately lateralizes the epileptogenic focus in TLE. Further studies are needed to define t he potential role of P300 in the presurgical evaluation of TLE.