ECG myogenic artifacts during clonic seizures: a disturbing (and interesting) finding

During motor seizures myogenic artifacts may appear on ECG. We report a patient with recurring convulsive seizures involving left side of his body in whom ECG served as a surrogate of electromyography (EMG), showing myogenic artifacts strongly correlated with clonic jerks. The possibility of standard ECG of recording myogenic potentials when clonic seizures occur is something intriguing, being at the same time both disturbing and informative. In such cases standard ECG works as an EMG, although ECG filter, sensitivity and paper speed is different from EMG currently used in neurophysiological laboratory. However, using standard ECG acquisition parameters, muscular activity may be recorded without excessive attenuation of high-frequency myogenic potentials, permitting to indicate the frequency of clonic movements. On the other hand, whenever possible, positioning of ECG surface electrodes on limbs not (or less) involved in clonic epileptic movements may permit to obtain a sufficiently informative ECG recording with less amount of myogenic artifacts, thus providing essential information on heart rate and rhythm.