Stress Urinary Incontinence in Women. Socio-Economic Relevance and Wavelet Analyses of Pelvic Floor Muscle Activation Patterns.

Student thesis: Doctoral Thesis


Background: One third of women are suffering from stress urinary incontinence (SUI). SUI often has a negative impact on women’s quality of life (QoL) and on their economic situation. However, in Switzerland, the societal cost-of-illness of SUI is not investigated yet. Therefore, the aim of the first study was, to estimate the socio-economic burden of SUI in Switzerland. High impact activities such as running are known to cause urinary leakage in women with SUI. Although running requires a fast and involuntary, reflexive PFM contraction there is still a lack of knowledge regarding PFM pre- and reflex activation behavior. Wavelet analyses of electromyograms (EMG) provide simultaneous information about the intensity of PFM activa- tion and the alpha-motoneurons and related fiber recruitment behavior at every time point of the gait cycle. Despite the fact that the benefit of wavelet analyses is particularly obvious in the evaluation of SUI-triggering activities such as running, this method has not yet been implemented in the analysis of PFM EMG. However, in consideration of the many different wavelet transforms, it is important to choose an appropriate function in order to be able to answer the research question. Therefore, the aim of the second study was to summarize wavelet applications to analyze the activity of the lower extremity muscles in different walking, running and orthopedic conditions. As a result, the purpose of the third study was to implement appropriate PFM EMG wavelet analysis methods and to improve knowledge about specific PFM EMG pre- and reflex activation patterns while running. As it is important to implement gained knowledge in a clinical context, it was aimed in the fourth study to use wavelet analyses to evaluate the effect of a well described, newly implemented physiotherapy program integrating involuntary PFM power training, compared with a standard physiotherapy program on PFM activation patterns and fiber type recruitment behavior while running.
The cost-of-illness study (COI) entitled “Health status, comorbidities and cost-of-illness in females with stress urinary incontinence living in the Canton of Bern” included 37 women with SUI. The study found that 95 % of the women with SUI had at least one additional comorbidity. The most commonly reported problems were back pain (47.6 %), followed by aller- gies (40.5 %) and joint problems (28.6 %). During the 16-weeks intervention phase, 51 % of the study participants consulted a medical doctor, and 43 % a specialist. The prevalence of drug consumption in this sample was 70 %. About 11 % of the participants reported less efficiency whilst working and 30 % less physical activity. Mental stress was mentioned by 60 % of the participants. From the societal perspective the average health costs were CHF 2256.-. The extrapolation of these 16-week costs of the study sample to the yearly costs yielded CHF 5258.-, which was about 30 % higher than the general Swiss female population.
The systematic review entitled “Wavelet analyses of electromyographic signals derived from lower extremity muscles whi- le walking or running: A systematic review” included 18 studies which used wavelet analyses to investigate EMG of lower extremity muscles. Thirteen studies investigated walking, four studies assessed running and one study focused on different walking and running conditions. Three main topics were discussed: 1.) The recognition rate which is the capability of the me- thod to correctly assign participants to a specific group, varied between 68.4 %-100 %. 2.) Persons with ankle osteoarthritis or total knee arthroplasty presented a delayed muscle activation in the early stance phase but a prolonged activation in mid stance. 3.) Atrophic muscles contained less type II muscle fiber components but generated more energy in their lower fre- quencies.
The cross-sectional study entitled “Pelvic floor muscle activity patterns in women with and without stress urinary incon- tinence while running” included 28 continent and 21 adult women with SUI. PFM EMG was recorded at 7, 11 and 15 km/h treadmill running and analyzed with Morse wavelets. The relative distribution of power was extracted within six 30 ms time intervals from 30 ms before to 150 ms after initial contact. The power spectra of each 30 ms time interval showed no statis- tically significant group differences. However, in the pre-initial contact phase, there was statistically significant less intensity in the lower but more intensity in the higher frequency bands than post-initial contact in both groups. This finding indicated a muscular preparation and adaptation a few milliseconds before initial contact.
The triple-blinded randomized controlled trial (RCT) entitled “Activation patterns of pelvic floor muscles in women with in- continence while running: A randomized controlled trial” included 39 women in the control group (CON) and 38 women in the experimental group (EXP). PFM EMG was measured before intervention and after 9 individual physiotherapy sessions. PFM EMG was recorded during 10 s at 7, 9 and 11 km/h treadmill running and analyzed with Morse wavelets. The relative distribution of power was extracted within six 30 ms time intervals. Statistical Parametric Mapping was performed to iden- tify power spectra differences pre and post intervention, within and between the two groups. The power spectra showed no statistically significant within and between group differences. Lowest frequencies 20-50 Hz: The time intervals from 30 ms before to 30 ms after initial contact showed statistically significant lower intensities than the intervals from 30-150 ms after initial contact for all running speeds and both groups. Highest frequencies 140-200 Hz: The time intervals from 30 ms before to 30 ms after initial contact showed statistically significant higher intensities than the time intervals from 30-150 ms after ini- tial contact for all running speeds and both groups. The power spectra shift towards higher frequency bands in the pre-initial contact phase could indicate a feed-forward anticipation and a muscle tuning for the expected impact of initial contact event in order to maintain continence during treadmill running at different speeds in adult women.
Date of Award2 Dec 2020
Original languageEnglish

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