Validity of Estimation of Pelvic Floor Muscle Activity from Transperineal Ultrasound Imaging in Men

Abstract

PurposeTo investigate the relationship between displacement of pelvic floor landmarks observed with transperineal ultrasound imaging and electromyography of the muscles hypothesised to cause the displacements.Materials and MethodsThree healthy men participated in this study, which included ultrasound imaging of the mid-urethra, urethra-vesical junction, ano-rectal junction and bulb of the penis. Fine-wire electromyography electrodes were inserted into the puborectalis and bulbocavernosus muscles and a transurethral catheter electrode recorded striated urethral sphincter electromyography. A nasogastric sensor recorded intra-abdominal pressure. Tasks included submaximal and maximal voluntary contractions, and Valsalva. The relationship between each of the parameters measured from ultrasound images and electromyography or intra-abdominal pressure amplitudes was described with nonlinear regression.ResultsStrong, non-linear relationships were calculated for each predicted landmark/muscle pair for submaximal contractions (R2–0.87–0.95). The relationships between mid-urethral displacement and striated urethral sphincter electromyography, and bulb of the penis displacement and bulbocavernosus electromyography were strong during maximal contractions (R2–0.74–0.88). Increased intra-abdominal pressure prevented shortening of puborectalis, which resulted in weak relationships between electromyography and anorectal and urethravesical junction displacement during all tasks.ConclusionsDisplacement of landmarks in transperineal ultrasound imaging provides meaningful measures of activation of individual pelvic floor muscles in men during voluntary contractions. This method may aid assessment of muscle function or feedback for training.

Influence of body position on dynamics of the pelvic floor measured with transperineal ultrasound imaging in men

“…Third, any potential caudal displacement of MU and BP with elevated IAP may be “canceled” by contraction of the muscles to resist lengthening. This would align with previous research that has shown that SUS and BC shorten with an increase in IAP 5 …”

“…Transperineal ultrasound imaging (TPUS) has recently been adapted from work in females 1–3 to assess pelvic floor muscle (PFM) function in males. Use of TPUS in the assessment of urinary incontinence 4,5 and pelvic pain 6 has rapidly been adopted into clinical practice 7 . Previous investigations of male PFM function using TPUS have been performed in supported, reclined long sitting, 4–6,8,9–13 because of the operational ease of ultrasound (US) assessment and retention of the effect of gravity on PFM in this position, but by contrast, TPUS has not been performed in standing before, possibly due to the greater technical difficulty in performing the measures in this position 14 .…”

“…5 During contraction, cranial-ventral displacement of the urethrovesical junction (UVJ) and cranial-ventral displacement of the anorectal junction (ARJ) relate to shortening of PR, dorsal displacement of the mid-urethra (MU) indicates SUS shortening, and ventral compression of the bulb of the penis (BP) relates to BC shortening. 5 Coordinated contraction of these muscles contributes to urinary continence, in conjunction with the smooth muscle of the urethra and bladder neck. 5,20 Furthermore, shortening (contraction) of these striated muscles is reduced in men with incontinence after prostatectomy.…”

Postprostatectomy incontinence is related to pelvic floor displacements observed with trans‐perineal ultrasound imaging

“…Non‐invasive transperineal ultrasound imaging provides an alternative method to study pelvic floor muscle function and recent investigations using this method have provided new insights . Using this technique muscle activation is quantified by displacement of landmarks in the ultrasound images, and this has been validated against measurement of muscle activation using invasive EMG recordings of SUS, PR, and BC . These studies have confirmed a relation between motion observed on ultrasound and activation of individual pelvic floor muscles in healthy men, thus enabling non‐invasive investigation of the continence mechanism in men with PPI.…”

“…Transperineal US is increasingly used by physiotherapists and nurses for assessment and biofeedback of pelvic floor muscle activation . These data provide new insight into features of pelvic floor muscle activation that are likely to be relevant for PPI.…”