EXTRAROLANDIC ORIGIN OF SPIKE AND MYOCLONUS ACTIVITY IN EPILEPSIA PARTIALIS CONTINUA - A MAGNETOENCEPHALOGRAPHIC AND POSITRON-EMISSION-TOMOGRAPHY STUDY

The dipole sources of interictal spike activity were localized and the myoclonus activity back-averaged by combined magnetoencephalography a nd surface electromyographic measurements in a child who had epilepsia partialis continua without a structural brain lesion. Dipole sources were matched with metabolic information obtained from interictal 5-flu oro-D-glucose positron emission tomography (PET) and superimposed onto high-resolution magnetic resonance images. Dipole sources of interict al epileptic discharges clustered within the inferior parietal cortex, which also showed a regional hypermetabolism on PET scans. The dipole sources of reafferent activity following myocloni in the postcentral gyrus were associated with a local hypometabolism. Although there was no obvious phase relationship between interictal spikes and myoclonic jerks, the myocloni were initiated from within the interictal spike ar ea in the extrarolandic cortex. The data demonstrate that motor sympto ms may be a remote effect of epileptic activity within functional brai n circuits.