New Frontiers of Intraoperative EMG Application
There appears to be a correlation between the muscles with objective EMG activation during intraoperative monitoring and the subjective paresthesia obtained postoperatively, as described in Tables 1-3. Thus, this may be explored to generate a precise model of paresthesia coverage and create a functional dermatomal mapping of perceived stimulation threshold after the surgery. Furthermore, the EMG activation threshold may be a reliable predictor of the patient’s perceived paresthesia threshold. It has been the author’s experience that EMG activation correlated with pain control at amplitudes lower than the paresthesia threshold (i.e. subthreshold stimulation), and that occasionally persistent EMG activation intra- and postoperatively may be seen lasting as long as 15 minutes after the stimulation is discontinued. These patients typically respond extremely well to the stimulation therapy. It seems likely that these patients are the occasional patients who use their stimulation only intermittently, often having effective long term pain relief while using their systems for only a portion of each day.