Hypothesis / aims of study
The possible role of pelvic floor muscle activity in male pelvic floor symptoms has not been studied thoroughly (1), due to difficulties in assessing pelvic floor muscle function in detail. These difficulties may be overcome with the Multiple Array Probe Leiden (MAPLe), a probe used to detect electromyography (EMG) signals from the different pelvic floor muscles (2). We explored pelvic floor muscle activity in men with and without lower urinary tract symptoms (LUTS), and with and without sexual dysfunction.
Study design, materials and methods
We conducted an observational cohort study in men with and without pelvic floor symptoms. For this, we invited all men aged >16 years, without a terminal disease, limited cognition or psychiatric or psychological problems, who lived in a Dutch municipality, to complete a questionnaire.
The International Consultation on Incontinence Questionnaire male LUTS Module (ICIQ-mLUTS) was used to assess LUTS, and categorize men into a group without symptoms (first quartile) and a group with severe symptoms (fourth quartile). Sexual functioning was assessed using the ‘Sexual Health in the Netherlands’ questionnaire and the ICIQ-Male Sexual Matters Associated with LUTS Module (ICIQ-MLUTSsex). Having erectile and/or ejaculation problems and/or pain during intercourse or ejaculation was defined as having sexual dysfunction. For this we selected sexually active men.
We selected men (aged >21 years), for additional measurements, based on their symptom scores, to allow comparison between men with and without symptoms. Measurements included a MAPLe assessment, according to the manufacturers’ protocol, including one-minute rest, ten maximum voluntary contractions (MVC) held for 1-2 seconds, and three sub-maximal endurance contractions held for 30 seconds. Raw output data of the MAPLe-measurements were retrieved for each of the 24 electrodes. Data were structured to assess muscle activity for the puborectal (PR) muscle, external anal sphincter (EAS), pubo- and iliococcygeal muscles (PIC) and the urogenital diaphragm (UDF).
Differences in pelvic floor muscle activity, for the three tasks and four muscle groups, between men with and without symptoms were analyzed using Mann-Whitney U Tests.
Data from 198 men (mean age 63.0±12.6 years) were available. Men without LUTS had 3 points or less on the ICIQ-mLUTS (n=61), men with severe symptoms had scores of 10 and higher (n=56). In total 158 men were sexually active (with or without partner); 75 men were classified as having sexual dysfunction.
In men with and without LUTS, no differences in pelvic floor muscle activity were recorded during rest-test, but MVC-outcomes were significantly lower in men with LUTS for PR, UDF and PIC (Table 1). During the endurance task, only PIC-activity was lower in men with LUTS, whereas other muscle groups showed no significant differences.
In men with and without sexual dysfunction no significant differences were found in any of the measurements (Table 1, Figure 1).
Interpretation of results
This is the first observational study in the general population comparing pelvic floor muscle activity in men with and without symptoms. Using the MAPLe device, we were able to collect detailed information on pelvic floor muscle activity for the relevant muscle groups and urogenital diaphragm. We used purposive sampling to compare men with and without symptoms. As such, this study does not reflect a random sample of the population.
No differences were found in men with and without sexual dysfunction. This could be explained by the combination of different sexual dysfunctions (erectile dysfunction, ejaculation disorders, pain) in the group with symptoms, which may have a different origin. We are unaware of other studies on this topic to allow comparisons.
Pelvic floor muscle activity during maximum voluntary contractions was notably different between men with and without LUTS. We have sought for a maximum difference, by categorizing men based on the lower and upper quartile of the ICIQ-mLUTS questionnaire. Outcomes of the maximum voluntary contraction assessment illustrate lower muscle activity in puborectal, and pubo- and iliococcygeal muscles, and the urogenital diaphragm. Due to the cross-sectional nature of this study, no causal associations can be shown. The clinical relevance of the differences is difficult to interpret, as no normal values or minimal clinically relevant differences (MCID) for muscle activities are available. Still, data illustrate that differences in pelvic floor muscle activities may indeed play a role in male LUTS. Ageing is associated with a decrease in proportion of fast-twitch type 2 fibers. This may explain the lower muscle activity measured in men with severe LUTS during maximum voluntary contraction, as this group is generally older than men without LUTS.