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 (10-55) motor unit action potential (MUP) analyses was identified and analyzed in multiple MUP analysis, and 14 (8-21) 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 turns-amplitude 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.