Reliability and differentiation of pelvic floor muscle electromyography measurements in healthy volunteers using a new device: the Multiple Array Probe Leiden (MAPLe)

A new multiple electrode probe, the Multiple Array Probe Leiden (MAPLe), has been developed for biofeedback registration of the individual pelvic floor musculature (PFM). The aim was to determine the reliability and differentiation of electromyography (EMG) signals measured with the MAPLe in healthy volunteers.

Two hundred twenty nine healthy volunteers not seeking treatment or using medication for symptoms of prolapse, lower urinary tract, bowel, pain, and/or sexual function related to pelvic floor dysfunction were qualified to participate. Subjects were asked to perform five tasks: rest, maximum voluntary contractions, endurance, cough, and valsalva. Mean EMG values per electrode were registered. Test-retest reliability was assessed using linear mixed model with random subject effects. One-way ANOVA tests were performed to detect differences between groups.

Magnetic resonance imaging (MRI) showed that each of the electrodes could be related nearest to the individual muscles. For test-retest, the intraclass correlation ranged from 0.53 to 0.91. The MAPLe showed significant differences in average EMG values between men and women, and between nulliparous and parous, pre- and prostmenpausal women. Significant differences were seen between the left and right sides of the pelvic floor. In addition, the activity nearest to the individual pelvic floor muscles (external anal sphincter (EAS), puborectalis muscle, bulbospongiosus, ischiocavernosus and the pubococcygeus muscle) could be determined.

The MAPLe is a reliable instrument measuring the EMG signals of the different sides and levels nearest to the pelvic floor musculature and is capable to differentiate between men and women, nulliparous, parous, pre- and postmenopausal. The findings of this study have implications for the diagnosis and treatment of pelvic floor dysfunction in the future.