Sensory and Motor Correlates of Stress Urinary Incontinence in Women
Creators: name: Brooks, Kaylee Christina Laura
Publisher: name: Université d'Ottawa | University of Ottawa
Year: 2024
Subjects: stress urinary incontinence
quantitative sensation testing
nerve conduction testing
pelvic floor muscles
proprioception
intravaginal dynamometry

description: Impairment of the sensorimotor system is suspected in women with stress urinary incontinence (SUI), but there is currently no consensus on its role in SUI pathophysiology. The primary aim of this dissertation was to explore differences in sensorimotor function of the pelvic floor muscles (PFMs) between women with and without SUI. The secondary aim was to explore which aspects of sensorimotor function (motor and sensory nerve function, PFM motor control and proprioception) may be different between women with SUI who were and were not cured of their symptoms with a physiotherapy intervention. A single protocol was developed to gather data for four distinct studies. The sample consisted of 30 cis women who completed two data collection sessions to record information on their sensorimotor function. Fourteen participants were continent, and 16 participants had SUI. Twelve of the 16 participants with SUI then attended a pelvic floor physiotherapy clinic of their choice, with the specific treatment provided left to the discretion of each physiotherapist. These participants were then asked to complete the International Consultation on Incontinence Questionnaire-Female Lower Urinary Tract Symptoms and the Global Rating of Patient Satisfaction and Perception of Improvement Questionnaire 12 weeks after their first appointment to determine if they were cured. The objective of the first study was to develop a standardized protocol for evaluating PFM proprioception. The assessments were based on tests used to evaluate limb proprioception and adapted for the pelvic floor. Using an intravaginal dynamometer (IVD), we identified an optimal signal processing protocol, and found that passive elongation and force-matching tasks provide different information about the proprioceptive function of the female-typical pelvic floor. We also found that visual feedback and contractile intensity may independently influence performance on the force-matching task. The objective of the second study was to compare, using an IVD, PFM motor function (e.g. strength, power, motor control) and proprioception between women with and without SUI, considering parity as a factor. Participants were asked to contract their PFMs with maximal effort and then perform one trial of a series of quick repeated contractions with the IVD. The protocol developed in objective one was used to assess proprioceptive function in women with and without SUI. The findings suggested that motor function and proprioception were not different between women with and without SUI. However, parous individuals displayed lower PFM force-generating capacity, a slower rate of force generation and relaxation, and no influence of visual feedback on the force-matching task compared to nulliparous women. This finding suggests that parity may influence PFM function, which may be important in understanding the pathophysiology of pelvic floor disorders. The secondary objective of the study was to determine which aspects of PFM function and proprioception may be different between women with SUI who were and were not cured of their symptoms through a physiotherapy intervention. The effect sizes suggested that women who were cured may demonstrate slower PFM force generation and relaxation and less accurate proprioception on a force-matching task at baseline compared to those who were not cured. The third objective was to investigate differences in light touch genital sensory thresholds between women with and without SUI. Using monofilaments and a method of levels approach to threshold testing, the regression models indicated that SUI was associated with high sensory thresholds at the perianal skin. Outliers from this analysis were identified as individuals with extremely high sensory thresholds, which suggests that focal disruptions of the branches of the pudendal nerve may be present, but impairment in the pudendal nerve as a whole is unlikely in women with mild to moderate SUI. The final objective was to explore differences in voluntary and evoked PFM activation between women with and without SUI. This was accomplished through stimulating the pudendal nerve intravaginally and recording the resultant evoked potentials from the levator ani, bulbospongiosus, urethral rhabdosphincter, and external anal sphincter muscles. Electromyographic signals were also recorded during maximal voluntary contraction efforts. The results did not support the presence of pudendal nerve impairment in women with mild to moderate SUI. Nor did the findings suggest that voluntary and evoked PFM activation influence physiotherapy treatment outcomes. When considered together, the results of these studies do not suggest that sensorimotor impairments of the PFMs are important to the pathophysiology of mild to moderate SUI. However, the impact of parity on PFM function warrants further study. The findings of this work may be used to direct future investigations of sensorimotor function in the pelvic floor to ultimately advance our understanding of pelvic floor disorders in women.