The Muscle Cells in Pelvic Floor Dysfunctions: Systematic Review

Background/Aims: The pelvic floor muscles are important structures involved in pelvic floor tone, pelvic organ support, and continence. The aim of this study was to perform an update on the pelvic floor muscle structure and function alterations of women with pelvic floor dysfunctions. Methods: A systematic search was undertaken in two electronic databases, PubMed/Medline and Ovid Discovery to find manuscripts (in English), published between 1 January 2002 and 31 July 2022, including all clinical studies using the following search terms: “muscle” or “extracellular matrix *” and “pelvic floor dysfunction *”. All clinical trials, observational, or animal studies examining the muscle and reporting pelvic floor dysfunction as a primary outcome were included. Case reports, literature reviews, conference papers and theses, and unpublished data were excluded. To ensure that no eligible articles were overlooked, the reference lists of all included papers underwent manual scrutiny. The bias level was estimated using Newcastle–Ottawa Scale (NOS) for cohort and case-control studies. A qualitative synthesis was performed. Results: The significant qualitative and quantitative heterogeneity between the studies did not allow for a quantitative analysis. Of the 30 articles selected with a total of 5592 women, 15 referred to the analysis of structural muscle defects, which included 3365 participants with urinary incontinence, pelvic organ prolapse, fecal incontinence, cistocele, rectocele, and sexual dysfunction; 10 manuscripts referred to the study of pelvic floor muscle function with a population of 2042 women, such as urinary incontinence, pelvic organ prolapse, fecal incontinence, and sexual dysfunction; and 5 papers evaluated cellular and/or molecular changes affecting the pelvic floor muscles, like urinary incontinence, pelvic organ prolapse, and rectocele, which included a total of 185 participants. Women with pelvic floor muscle defects are at greater risk of pelvic floor dysfunctions, and inversely, women with pelvic floor dysfunctions have more pelvic floor muscle defects than women without pelvic floor dysfunctions. These patients demonstrate a reduction in muscle tone, contraction strength, and resistance, a compromised neuromuscular activity, and an alteration of the normal composition and organization of the muscle cells. Conclusions: Women with pelvic floor dysfunction have anatomical muscle defects, disturbance of muscle function and cellular changes involving muscle cells and nerve fibers.