ABNORMAL CORTICAL ACTIVATION DURING PLANNING OF VOLUNTARY MOVEMENT INPATIENTS WITH EPILEPSY WITH FOCAL MOTOR SEIZURES - EVENT-RELATED DESYNCHRONIZATION STUDY OF ELECTROENCEPHALOGRAPHIC MU-RHYTHM

Purpose: The spatiotemporal distribution of EEG mu rhythm desynchroniz ation was analyzed in patients with partial epilepsy to determine whet her frequent focal motor seizures could induce a change of cortical ac tivation during the planning of a voluntary movement. Methods: The eve nt-related desynchronization (ERD) of the mu rhythm was quantified dur ing a self-paced voluntary movement of the thumb. The results were com pared between two groups of patients with epilepsy: in one group (n = 12), the patients had frontal lobe epilepsy with frequent focal motor seizures (FMS); in the second group (n = 12), they had temporal lobe e pilepsy (TLE) with complex partial seizures but no ictal movement diso rder. The results were also compared with those of control subjects of same age (n = 10). Results: In the control group, desynchronization o f mu rhythm began over the contralateral central region 2,000 ms befor e the movement onset. In the FMS group, the desynchronization of mu rh ythm was delayed, appearing only 500 ms before the movement onset, and the amplitude of ERD was increased over the frontocentral region. In the TLE group, the spatiotemporal pattern of ERD was the same as in no rmal subjects, but the amplitude of ERD was increased. Conclusions: Th ese results indicate that there is a change of reactivity of mu rhythm in patients with partial epilepsy. The change in spatiotemporal patte rn of ERD in patients with frequent focal motor seizures suggests that there is an abnormal cortical activation during the planning of a vol untary movement.