Exploring pelvic floor muscle activity in male lower urinary tract symptoms

HYPOTHESIS/AIMS OF STUDY: Although male lower urinary tract symptoms (LUTS) have a multifactorial origin, the potential role of pelvic floor muscle (PFM) function has not been studied well in men. This may be due to difficulties in the assessment of PFM activity. These difficulties may be overcome using the Multiple Array Probe Leiden (MAPLe®), which is a probe with a matrix of 24 elec-trodes capable of anally registering EMG signals of individual pelvic muscles (1). To date, reported data in males incorporated healthy men only. We are unaware of any studies in male patients with LUTS. Therefore, the aim of the present study was to explore the association between PFM activity and symptom severity in men with LUTS. STUDY DESIGN, MATERIALS AND METHODS: We performed an observational study including adult men referred to a urology outpatient department for uncomplicated LUTS. As part of the standardized outpatient assessment, all men completed questionnaires (International Prostate Symptom Score (IPSS) and Overactive Bladder Symptom Score (OABSS)) before their first appointment. Patients (>18 years of age) with an IPSS score of 8 or higher were eligible for this study. Patients with insufficient knowledge of the Dutch language, a history of prostate cancer, bladder cancer, or prostate or bladder surgery were excluded. Men who were willing to participate provided written informed consent. Directly following the urologist appointment, additional assessment of the pelvic floor muscles was performed using MAPLe®, according to the manufacturers' protocol. This included the following tasks in supine position: 1-minute rest, five maximum voluntary contractions (MVC) held for 3 seconds and three maximal endurance contractions held for 15 seconds. We retrieved raw output data (for each electrode) through the MAPLe® manufacturer. These data were used to assess muscle activity, during each task, for the following PFM groups: puborectalis (PR), external anal sphincter (EAS), internal anal sphincter (IAS), pubo-and iliococcygeus (PIC) and urogenital diaphragm (UDF). So, for each PFM group three outcomes were calculated. To explore the possible association between PFM groups, we present the outcomes of the five muscle groups for the three tasks (rest activity, MCV and endurance). Friedman's test with a post hoc analysis Wilcoxon signed ranks test was used to assess the difference in uV between the different pelvic floor muscle groups, separately for the three tasks. To explore the possible association between PFM activity and symptom severity, we applied correlation coefficients between the outcomes of the PFM activity and the OABSS and IPSS scores. A Bonferroni correction for multiple testing was applied. A p-value of 0.005 or smaller was considered statistically significant. RESULTS: Data from 57 men (aged 67±10 years, mean IPSS score 19.2±6.2, mean OABSS score 6.1 ±3.2) showed that during the 1-minute rest task no significant differences were measured between the separate muscle groups (Figure 1 A). Therefore, in further analyses the five muscle groups were combined for the 1-minute rest task. During the MVC task the EAS showed signifcantly lower muscle activity (μV) than the IAS and PR (Figure 1B). During the endurance task, the EAS had a signifcantly lower muscle activity (μV) than the other four muscle groups (Figure 1C). There were no signifcant associations between PFM activity and symptoms measured with IPSS and OABSS (Table 1). The highest correlation coeficient was 0.21. None of the coef-cients was statistically signifcant (all p >0.005). INTERPRETATION OF RESULTS: PFM rest activity did not difer between the fve muscle groups. However, the EAS showed lower muscle activity than the other muscle groups during the MVC and endurance tasks. In general, muscle activity was lower for all muscle groups and all tasks when compared with the results from an earlier study in healthy subjects (1). In our study, the EAS showed the lowest muscle activity in all three tasks, while the EAS showed the highest activity in the study with healthy volunteers. We cannot explain these diferences, as one might expect higher PFM activity in men with LUTS. Measurements were performed using the same protocol in both studies. The absence of an association between PFM activity and LUTS symptom severity in our study needs further exploration. It is unclear if this is due to a true absence of such association, or due to the MAPLe® assessment, or testing situation (not during voiding). CONCLUDING MESSAGE: This is the frst study exploring PFM activity in a large group of men with LUTS. We found no association between PFM activity and LUTS severity as measured by OABSS and IPSS. Future studies should explore this in more detail, possibly looking for subgroups of patients with pelvic foor problems. Furthermore, larger studies in the general population are warranted to generate normal values of PFM activity. Of specifc interest would be to monitor PFM activity during voiding