Neuromuscular characterization of the urethra in continent women

Objectives: The study's objective was to describe quantitative urethral function parameters in a racially diverse group of continent women. Materials and Methods: After institutional review board approval, we recruited women without urinary incontinence from the community. To be considered continent, participants answered "never" to the first 6 questions on the stress subscale of the Medical, Epidemiologic, and Social Aspects of Aging urinary incontinence questionnaire. Participants all underwent quantitative concentric urethral electromyography (EMG) and urodynamic testing. Results: Thirty-one women with a mean (SD) age of 39 (14) years underwent EMG and urodynamic testing. The cohort was racially diverse with 13 (43%) white women, 13 (43%) African American women, and 4 (14%) Hispanic women. Body mass index (P = 0.12, 0.06), age (P = 0.40, 0.64), and vaginal parity (P = 0.53, 0.76) did not differ by race or ethnicity.We did not detect differences in any EMG parameter by race, ethnicity, or vaginally parity. A mean (range) of 30 (10Y55) motor unit action potential (MUP) analyses was identified and analyzed in multiple MUP analysis, and 14 (8Y21) were identified and analyzed in interference pattern (IP) analysis. On average, 37% (20%) (mean [SD]) MUPs were polyphasic. Age significantly correlated with several measures of urethral sphincter function. Increasing age was inversely correlated with IP turns (r = -0.57, P = 0.001), IP amplitude (r = -0.43, P = 0.02), IP turnsamplitude ratio (r = -0.54, P = 0.003), and maximum urethral closure pressures (r = -0.41, P = 0.04). Similarly, maximum urethral closure pressures correlated with IP amplitude (r = 0.38, P = 0.04). Conclusions: These urethral neuromuscular function data on the largest cohort of continent women fully characterized with quantitative urethral EMG demonstrate significant neuropathic MUP changes with advancing age.