Neuromuscular urethral function and urethral urodynamic parameters between urgency and stress incontinence do not differ

To describe and compare urethral neuromuscular function using concentric needle electromyography (CNEMG) and urodynamic (UDS) parameters between stress incontinent (SUI) and urge incontinent (UUI) women.

Incontinent women were recruited from a urogynecology clinic if they answered “sometimes” or “always” to one of the items on the Medical, Epidemiologic, and Social Aspects of Aging questionnaire. Participants were categorized by MESA scores into stress (SUI) or urgency (UUI) incontinence groups. Participants underwent CNEMG of the striated urethral sphincter at three insertion sites using Medtronic multiple motor unit action potential analysis. UDS was performed with Laborie microtip catheters: urethral pressure profiles were obtained at baseline and 300 ml. Data were analyzed in SPSS. Continuous variables were compared with independent t-test or Mann-Whitney U, categorical variables with chi-square test. A logistic regression was performed to control for variables found to be significant on univariate analysis.

Fifty-six women (37 SUI, 19 UUI) with mean ± SD age of 53 ± 13 years participated. At baseline, patients with SUI were younger, more likely to be premenopausal and had lower BMIs. There were no differences in urethral EMG or UDS parameters between UUI and SUI women except lower maximum cystometric capacity in women with UUI. When controlling for age, BMI and MCC on logistic regression, there remained no differences between SUI and UUI groups on EMG or UDS parameters.

Women with UUI and DO show similar evidence of denervation-reinnervation injury to the striated urethral sphincter muscle as women with SUI.