The temporal relationship between activity of the pelvic floor muscles and motion of selected urogenital landmarks in healthy nulliparous women.

AIMS: The purpose of this study was to investigate the relationship between pelvic floor muscle (PFM) electromyographic (EMG) activation and urogenital landmark motion measured using 2D transperineal ultrasound (US) imaging. METHODS: Eight healthy, nulliparous women performed maximum voluntary PFM contractions while EMG and transperineal US images were acquired simultaneously. Changes in the levator plate length (LPL), bladder neck (BN) position and urethral position were determined by visual inspection. The relative timing of EMG onset and the onset of landmark motion, and the correlation coefficients between EMG activation and landmark motion were computed. Comparisons between the correlation coefficients and onset latencies of each landmark motion were made using one-way analysis of variance models. RESULTS: Despite generally good reliability metrics for the onset of EMG and the onset of landmark motion, the relative timing of EMG onset and the onset of landmark motion demonstrated no systematic patterns of activation onset. That said, the overall motion of the different urogenital landmarks throughout the MVC task was highly correlated with the PFM EMG data; correlation coefficients were generally good (>0.90) and highly significant (p < .001). The correlation between PFM EMG and LPL motion was significantly better than the correlation between PFM EMG and motion of the other landmarks. The relevance of one outlier is discussed. CONCLUSIONS: The motion of all urogenital landmarks seen on US imaging is highly correlated with PFM EMG activation during maximum voluntary PFM contractions and may therefore be of value in the context of biofeedback training to infer that PFM activation has occurred. The motion of the BN, however, may require more cautious interpretation than the reduction of LPL. The timing of the onset of urogenital landmark motion on transperineal US imaging does not precede nor follow the timing of PFM activation, while the high variance of relative onset timing makes the onset of landmark motion of questionable value when training or evaluating co-ordination or motor control.

Pelvic floor ultrasound imaging: are physiotherapists interchangeable in the assessment of levator hiatal biometry?

PURPOSE: To evaluate inter-examiner reliability in the ultrasound (US) assessment of levator hiatal dimensions when different physiotherapists perform independent data acquisition and analysis. METHODS: In this cross-sectional observational study, 14 asymptomatic nulliparous women were imaged at rest, during pelvic floor muscle contraction, and during Valsalva manoeuvre by two physiotherapists using three-dimensional (3D) and four-dimensional (4D) transperineal US. Examiners each measured the dimensions of the levator hiatus (area and antero-posterior and transverse diameters) from the US volumes they respectively acquired. Inter-examiner reliability was determined using intra-class correlation coefficients (ICCs), and inter-examiner agreement was determined using Bland-Altman analyses. RESULTS: The ICC results demonstrated very good inter-examiner reliability (ICC=0.84-0.98); Bland-Altman results showed high inter-examiner agreement across all measurements. CONCLUSIONS: Trained examiners may be considered interchangeable in the US assessment of levator hiatal biometry. Overall, trained physiotherapists using transperineal US imaging to assess levator hiatal biometry can be confident when comparing their own clinical findings to those of their colleagues and to findings published in the literature.

Objectif : Examiner la fiabilité entre examinateurs de l'évaluation échographique des dimensions hiatales du muscle releveur de l'anus lorsque des physiothérapeutes différents procèdent à l'acquisition et à l'analyse indépendante de données. Méthodes : Au cours de cette étude par observation transversale, 14 femmes nullipares asymptomatiques ont subi un examen d'imagerie au repos, au cours d'une contraction des muscles du plancher pelvien et durant une manœuvre de Valsalva, effectué par deux physiothérapeutes utilisant l'échographie transpérinéale tridimensionnelle (3D) et quadridimensionnelle (4D). Chaque examinateur a mesuré les dimensions du hiatus du muscle releveur (superficie et diamètre antéropostérieur et transversal) à partir des volumes échographiques qu'ils ont acquis respectivement. On a déterminé la fiabilité entre examinateurs à partir des coefficients de corrélation intra-classe (CCI) et déterminé l'uniformité entre examinateur au moyen des analyses de Bland et d'Altman. Résultats : Les résultats de l'application des CCI ont révélé une très bonne fiabilité entre examinateurs pour toutes les mesures. (CCI=0.84­0.98); les résultats de Bland et Altman ont révélé une grande uniformité entre examinateurs pour toutes les mesures. Conclusions : Les examinateurs qui ont reçu une formation peuvent être considérés comme interchangeables dans l'évaluation échographique de la biométrie hiatale du muscle releveur. Dans l'ensemble, les physiothérapeutes qui ont suivi une formation et utilisent l'imagerie échographique transpérinéale pour évaluer la biométrie hiatale du muscle releveur peuvent comparer en toute confiance leurs constatations cliniques à celles de leurs collègues et à celles des publications.

Does the presence of a vaginal probe alter pelvic floor muscle activation in young, continent women?

Vaginal probes may induce changes in pelvic floor muscle (PFM) recruitment by the very presence of the probes. Fine-wire electrodes allow us to detect muscle activation parameters without altering the natural position and shape of the PFMs. The purpose of this study was to determine whether PFM activation is altered by changes in sensory feedback, muscle length or tissue position caused by two different vaginal probes used to record surface electromyography (EMG). Twelve continent women (30.1 ± 5.4 years), performed PFM maximal voluntary contractions (MVCs) in supine while fine-wire EMG was recorded bilaterally from the PFMs under three conditions: (a) without any probe inserted into the vagina, (b) while a Femiscan™ probe was in situ, and (c) while a Periform™ vaginal probe was in situ. The reliability of the fine wire EMG data was assessed using intra-class correlation coefficients (ICCs) and coefficients of variation (CV). A repeated measures analysis of variance (ANOVA) model was used to determine if there were differences in EMG amplitude recorded when the different vaginal probes were in situ. For each condition the between-trial reliability was excellent, ICC((3,1)) = 0.93-0.96, (p < 0.001) and CV = 11.2-21.8%. There were no differences in peak EMG amplitude recorded during the MVCs across the three conditions (no probe 63.4 ± 48.4 µV, Femiscan™ 55.3 ± 42.4 µV, Periform™ 59.4 ± 42.2 µV, p = 0.178). These results suggest that women produce consistent MVCs over multiple contractions, and that PFM muscle activation is not affected by different probes inserted into the vagina.

The reliability of surface EMG recorded from the pelvic floor muscles.

The neuromuscular function of the pelvic floor muscles (PFMs) is frequently evaluated using surface electrodes embedded on vaginal probes. The purpose of this study was to determine the between-trial and between-day reliability of EMG data recorded from the PFM using two different vaginal probes while subjects performed PFM maximum voluntary contractions and a coughing task. The Femiscan and the Periform vaginal probes were used to acquire EMG data while the subjects performed the tasks. Peak RMS amplitudes were computed for each instrument, task, and side of the pelvic floor using a sliding window technique. The between-trial reliability was evaluated using intraclass correlation coefficients (ICCs) and coefficients of variation (CV). Between-trial reliability was determined using ICCs, Pearson's correlation coefficients, computing the mean absolute difference between days, and calculating the standard error the measurement (SEM) for each instrument and task. EMG amplitude differences were detected between the left and right PFM (p<0.05), therefore all of the analyses were performed separately for each side. Overall, between-trial reliability was fair to high for the Femiscan (ICC((3,1))=0.58-0.98, CV=8.5-20.7%) and good to high for the Periform (ICC((3,1))=0.80-0.98, CV=9.6-19.5%), however between-day reliability was generally poor for both vaginal probes (ICC((3,1))=0.08-0.84). The results suggest that although it is acceptable to use PFM surface EMG as a biofeedback tool for training purposes, it is not recommended for use to make between-subject comparisons or to use as an outcome measure between-days when evaluating PFM function.