Multiscale entropy analysis of surface electromyographic signals as a prognostic indicator for subtle functional impairment of urethral sphincter

To explore information hidden in the electromyographic (EMG) signals of urethral sphincter, 19 patients with voiding difficulty were divided into two groups: Patients with detrusor overactivity (Group 1, n=7), detrusor-external sphincter dyssynergia (Group 2, n=12). All patients underwent baseline urodynamic studies for comparison. The results demonstrated that, despite no significant difference in urodynamic parameters between Group 1 and Group 2, the large-scale MSE of preoperative EMG [i.e., MSELS(EMG)] and small-scale MSE of preoperative EMG [i.e., MSESS(EMG)] of Group 1 were notably higher than those of Group 2 (i.e., patients with abnormal sphincter function). In conclusion, using MSE analysis for assessing preoperative urethral sphincter EMG signals successfully distinguished the subtle functional impairment of urethral sphincter unable to be detected by routine urodynamic studies.