To explore information hidden in the electromyographic (EMG) signals of the urethral sphincter that may be of prognostic significance for patients with primary bladder neck obstruction (PBNO), 41 patients with voiding difficulty were divided into four groups: 1) patients with primary bladder neck obstruction (PBNO) with successful (Group 1, n
= 14) and 2) unsuccessful (Group 2, n
= 8) surgical outcomes, 3) patients with detrusor overactivity (Group 3, n
= 7), and 4) patients with detrusor-external sphincter dyssynergia (Group 4, n
= 12). All patients underwent baseline urodynamic studies (preoperative for Group 1 and Group 2) for comparison. The results demonstrated that, despite no significant difference in urodynamic parameters between Group 1 and Group 2, the large-scale multiscale entropy (MSE) of preoperative EMG (i.e
(EMG)) of Group 1 was significantly higher than that of Group 2 without notable difference between Group 1 and Group 3 (i.e.
, patients with normal sphincter function). Moreover, the MSELS
(EMG) and small-scale MSE of preoperative EMG (i.e
(EMG)) of Group 2 were notably higher than those of Group 4 (i.e
., patients with abnormal sphincter function), while both MSELS
(EMG) and MSESS
(EMG) of Group 3 were notably higher than those of Group 2. In conclusion, using MSE analysis for assessing preoperative urethral sphincter EMG signals successfully distinguished between PBNO patients with subsequent successful surgery from those with surgical failure possibly due to subtle functional impairment of the urethral sphincter that cannot be detected by routine urodynamic studies. The results, therefore, highlight the potential clinical significance of this analytical tool in guiding urologists regarding their choice of medical versus
surgical treatment for this patient population.