Reliability of different electromyographic normalization methods for pelvic floor muscles assessment

Techniques for Registration of Myoelectric Activity of Women's Pelvic Floor Muscles: A Scoping Review

INTRODUCTION AND HYPOTHESIS

Surface electromyography is commonly applied to measure the electrophysiological activity of the neuromuscular system. However, there is no consensus regarding the best protocol to assess pelvic floor muscles.

METHODS

A scoping literature review was carried out in six databases, using MeSH descriptors. It included studies with electromyographic assessment in adult women presenting or not with pelvic floor dysfunction. The results were presented in categories to contribute to the development of a protocol considering the most used parameters for non-invasive assessment of myoelectric activity of pelvic floor muscles.

RESULTS

A total of 1,074 articles were identified, and 146 studies were selected for analysis. The intravaginal probe was used in 80.8% of the studies, the bipolar sensor with metallic plates placed on both sides of the vagina was the most frequent (71.3%), with a reference electrode positioned on the anterior superior iliac spine (33.5%). The supine position with hip and knee flexed (45.2%) was the most frequent position used. Of the studies, 44.5% normalized the data by maximum voluntary contraction (MVC) whereas 44.5% performed an average of 3 MVCs.

CONCLUSIONS

The most frequently used protocol for the pelvic floor is the bipolar intracavitary probe with metal plates positioned at 3-9 o'clock and introduced distally to the vaginal introitus with the volunteer in the supine position and the hip and knee flexed with the reference placed on the anterior-superior iliac spine.

Neutral posture education during cough can reduce urine leakage in women with cough-related stress urinary incontinence

BACKGROUND

Current literature highlights the difficulty in identifying an optimal educational technique for maintaining continence during cough.

OBJECTIVE

To characterize the effects of an educational intervention focusing on neutral posture during cough in women with cough-induced urinary incontinence (UI).

METHODS

This interventional study design included women with cough-induced UI. We recorded PFMs surface electromyographic (sEMG) peak activity, and assessed symptoms and quality of life (QoL) 6 weeks after the intervention. The effect of the experimental situation was estimated using a linear mixed model, sEMG measurements during coughing were indexed to each situation and adjusted to the resting value at, and a moderation analysis was used.

RESULTS/FINDINGS

Eighteen participants were included. The measurement situations (control versus experimental) did not have a statistically significant impact on sEMG peak activity during coughing: mean effect [95% CI] 3.42 [-1.28; 7.66]. Six weeks post-intervention, participants reported statistically significant decrease in urinary symptoms (P=0.0246) and significant improvement in QoL (P=0.00776). This was also particularly marked on the dimension related to effort activities (P=0.00162).

CONCLUSION

This study suggests that a brief educational intervention focusing on neutral posture during cough, without voluntary pre-contraction of the PFMs, has no clinically significant influence on sEMG peak activity of the PFMs in women with cough-induced UI. However, this intervention can lead to a significant improvement in urinary symptoms and QoL at 6 weeks. These improvements seem to be independent of electromyographic PFMs peak activity recorded during cough. As such, our preliminary results pave the way for future research.

LEVEL OF EVIDENCE

NP4.

Evaluation of Pelvic Floor Muscles in Pregnancy and Postpartum With Non-Invasive Magnetomyography

Objective: To record and characterize features of levator ani muscles (LAM) activity in pregnancy and postpartum using non-invasive and novel Magnetomyography (MMG) technique with amplitude and spectral parameters. Methods: Nulliparous women with uncomplicated pregnancies participated in the MMG data collection during rest and voluntary LAM contractions (Kegels) with modulated intensity in third trimester and approximately 2 months postpartum (PP). Simultaneous surface electromyography was recorded to document the recruitment of accessory muscles. Moderate strength Kegel (MK) MMG trials were analyzed. Amplitude and spectral parameters including root-mean square (RMS) amplitude, power spectrum density (PSD) and normalized PSD (rPSD) in three frequency bands (low, middle, high) were computed on MK epochs. Statistical comparisons between pregnancy and postpartum were calculated. Results: MMG recordings were measured from 10 pregnant women. Results showed decreased RMS and power between third trimester and postpartum, trending towards significance. rPSD values in the low frequency band decreased significantly (p = 0.028) from third trimester to postpartum, while significant increase was observed in the middle frequency band (p = 0.018). Conclusions: This study shows that MMG as non-invasive tool has the ability to detect and characterize changes of LAM activity with amplitude and spectral parameters during pregnancy and postpartum.

The Effects of the Biceps Brachii and Brachioradialis on Elbow Flexor Muscle Strength and Spasticity in Stroke Patients

Objective

Muscle weakness and spasticity are common consequences of stroke, leading to a decrease in physical activity. The effective implementation of precision rehabilitation requires detailed rehabilitation evaluation. We aimed to analyze the surface electromyography (sEMG) signal features of elbow flexor muscle (biceps brachii and brachioradialis) spasticity in maximum voluntary isometric contraction (MVIC) and fast passive extension (FPE) in stroke patients and to explore the main muscle groups that affect the active movement and spasticity of the elbow flexor muscles to provide an objective reference for optimizing stroke rehabilitation.

Methods

Fifteen patients with elbow flexor spasticity after stroke were enrolled in this study. sEMG signals of the paretic and nonparetic elbow flexor muscles (biceps and brachioradialis) were detected during MVIC and FPE, and root mean square (RMS) values were calculated. The RMS values (mean and peak) of the biceps and brachioradialis were compared between the paretic and nonparetic sides. Additionally, the correlation between the manual muscle test (MMT) score and the RMS values (mean and peak) of the paretic elbow flexors during MVIC was analyzed, and the correlation between the modified Ashworth scale (MAS) score and the RMS values (mean and peak) of the paretic elbow flexors during FPE was analyzed.

Results

During MVIC exercise, the RMS values (mean and peak) of the biceps and brachioradialis on the paretic side were significantly lower than those on the nonparetic side (p < 0.01), and the RMS values (mean and peak) of the bilateral biceps were significantly higher than those of the brachioradialis (p < 0.01). The MMT score was positively correlated with the mean and peak RMS values of the paretic biceps and brachioradialis (r = 0.89, r = 0.91, r = 0.82, r = 0.85; p < 0.001). During FPE exercise, the RMS values (mean and peak) of the biceps and brachioradialis on the paretic side were significantly higher than those on the nonparetic side (p < 0.01), and the RMS values (mean and peak) of the brachioradialis on the paretic side were significantly higher than those of the biceps (p < 0.01). TheMAS score was positively correlated with the mean RMS of the paretic biceps and brachioradialis (r = 0.62, p = 0.021; r = 0.74, p = 0.004), and the MAS score was positively correlated with the peak RMS of the paretic brachioradialis (r = 0.59, p = 0.029) but had no significant correlation with the peak RMS of the paretic biceps (r = 0.49, p > 0.05).

Conclusions

The results confirm that the biceps is a vital muscle in active elbow flexion and that the brachioradialis plays an important role in elbow flexor spasticity, suggesting that the biceps should be the focus of muscle strength training of the elbow flexors and that the role of the brachioradialis should not be ignored in the treatment of elbow flexor spasticity. This study also confirmed the application value of sEMG in the objective assessment of individual muscle strength and spasticity in stroke patients.

Electromyographic analysis of maximal voluntary contraction of female pelvic floor muscles: Intrarater and interrater reliability study

AIMS

To investigate the intrarater and interrater reliability of the surface electromyography (sEMG) of female pelvic floor muscles (PFM) by visual determination of the onset-offset during maximal voluntary contraction (MVC).

METHODS

Intrarater and interrater reliability study. Three MVC, recorded for 5 s (s) each and separated by intervals of 60 s, were requested. Two independent raters visually determined the onset and offset of each MVC. The agreement between raters on the quality of the signals was analyzed both qualitatively (visual inspection) and quantitatively (signal-to-noise ratio, SNR). The reliability of integral and median frequency (MDF) of sEMG signals during MVC was analyzed using intraclass correlation coefficient (ICC) models (ICC_2,1 , ICC_2,3 ) and repeated measures analysis of variance.

RESULTS

A total of 58 women (mean age of 54 years) and two independent raters participated in the analyses. Of the total, 22 (37.9%) were considered of high quality by both raters and the SNR ranged 34.3-22.2 decibels (dB). The agreement of qualitative visual evaluation of the sEMG signal was fair (Cohen's κ = 0.306 [0.148; 0.463]). Intrarater and interrater reliability were excellent for the average of the three MVC, both for integral (ICC_2,3  = 0.884 [0.821; 0.925]; ω²  = -0.006, p = 0.558) and MDF (ICC_2,3  = 0.998 [0.998; 0.999]; ω²  = -0.009, p = 0.992).

CONCLUSION

Qualitative visual analysis of the sEMG signal presents fair interrater agreement and reflects the SNR. Visual determination of the onset and offset of the MVC of PFM using the standard interface of the sEMG software has excellent reliability for determination of muscle activation variables.

The pathophysiology of stress urinary incontinence: a systematic review and meta-analysis

Introduction and hypothesis

To evaluate the evidence for pathologies underlying stress urinary incontinence (SUI) in women.

Methods

For the data sources, a structured search of the peer-reviewed literature (English language; 1960–April 2020) was conducted using predefined key terms in PubMed and Embase. Google Scholar was also searched. Peer-reviewed manuscripts that reported on anatomical, physiological or functional differences between females with signs and/or symptoms consistent with SUI and a concurrently recruited control group of continent females without any substantive urogynecological symptoms. Of 4629 publications screened, 84 met the inclusion criteria and were retained, among which 24 were included in meta-analyses.

Results

Selection bias was moderate to high; < 25% of studies controlled for major confounding variables for SUI (e.g., age, BMI and parity). There was a lack of standardization of methods among studies, and several measurement issues were identified. Results were synthesized qualitatively, and, where possible, random-effects meta-analyses were conducted. Deficits in urethral and bladder neck structure and support, neuromuscular and mechanical function of the striated urethral sphincter (SUS) and levator ani muscles all appear to be associated with SUI. Meta-analyses showed that observed bladder neck dilation and lower functional urethral length, bladder neck support and maximum urethral closure pressures are strong characteristic signs of SUI.

Conclusion

The pathology of SUI is multifactorial, with strong evidence pointing to bladder neck and urethral incompetence. While there is also evidence of impaired urethral support and levator ani function, standardized approaches to measurement are needed to generate higher levels of evidence.