Why are some women with pelvic floor dysfunction unable to contract their pelvic floor muscles?

Transcription

1 Australian and New Zealand Journal of Obstetrics and Gynaecology 2013; 53: DOI: /ajo Original Article Why are some women with pelvic floor dysfunction unable to contract their pelvic floor muscles? Sia KIM, 1 Vivien WONG 1 and Kate H. MOORE 2 1 Pelvic Floor Unit, St George Hospital, and 2 Department of Urogynaecology, University of New South Wales (UNSW), Sydney, New South Wales, Australia Introduction: Many women with pelvic floor dysfunction are unable to voluntarily contract their pelvic floor muscles. This study hypothesised that women who cannot contract their pelvic floor muscles, despite specialised pelvic floor physiotherapy, are likely to have avulsion defect of the levator ani muscle, visible on 3-dimensional ultrasound. Methods: Pelvic floor muscle strength was assessed by modified Oxford scale in all women presenting to a tertiary urogynaecology clinic with a main complaint of urinary incontinence pelvic organ prolapse. Women who could not contract their pelvic floor muscles (PFM) after having training with a specialised pelvic floor physiotherapist, (modified Oxford score of 0 or 1), were invited to participate in 3-dimensional transperineal ultrasound. Results: Of 625 women presenting with urinary incontinence and/or pelvic organ prolapse, 150 (24.0%) were unable to contract their PFM at initial assessment. After specialised pelvic floor physiotherapy, 20 of 150 (15.3%) could not contract and were termed noncontractors. Of these, 12 agreed to participate in transperineal ultrasound. Levator avulsion defects were detected in 8 of 12 (66.7%). Conclusion: Our results show that 67% of women who cannot contract their PFM despite physiotherapy have levator avulsion defects. The mechanism affecting the remaining 33% is yet to be discovered. Key words: levator avulsion, pelvic floor muscle, pelvic floor muscle strength, pelvic floor muscle training, physiotherapy. Introduction Amongst women with pelvic floor dysfunction, it has long been known that PFM training is first-line therapy for stress incontinence. Recently, pelvic organ prolapse has also been effectively treated by PFM training. 1 One of the difficulties that clinicians often find upon examination is that many women are unable to contract their PFM. This may give rise to a pessimistic outlook as to the success of PFM training. The present literature contains little information as to whether such pessimism is warranted or unfounded in women with pelvic floor dysfunction. One of the factors associated with pelvic floor dysfunction is levator avulsion, which is a traumatic detachment of the puborectalis muscle from its insertion on the inferior pubic Correspondence: Professor Kate H. Moore, First Floor Pitney Clinical Science Building, St George Hospital, Gray St Kogarah NSW 2217, Australia. k.moore@unsw.edu.au Conflict of interest: None of the authors have any financial involvement within the past five years with a commercial organisation that might have any potential interest in the subject or materials discussed in the manuscript. Funding: Pelvic floor research trust fund. Received 12 March 2013; accepted 9 August rami. This occurs following vaginal delivery in up to 36% of women. 2 This type of trauma is shown to be associated with reduced pelvic floor muscle strength, 3 excessive distensibility of the levator hiatus 2 as well as anterior and central compartment prolapse. 4 More recently, levator avulsion defects were found to be strongly associated with recurrent prolapse after reconstructive surgery. 5 7 In women who are unable to tighten their PFM upon examination by a gynaecologist, pelvic floor muscle training delivered by a specialist physiotherapist can strengthen the PFM, like any other skeletal muscle. 8,9 High-resistance physiotherapy training results in PFM hypertrophy and increased strength. 10 However, some women remain unable to voluntarily contract their PFM despite such training, a phenomenon that is poorly documented in the literature. Furthermore, the association between puborectalis muscle injury (or the excessive distension of the levator hiatus) and the ability to perform a PFM contraction has received scanty attention in the literature. In 2009, Sarma et al. 11 showed that 40% of women who were unable to contract had a levator avulsion defect on ultrasound, but all had normal urethral sphincter concentric needle EMG studies (i.e normal pelvic innervation). However, the study population comprised women with stress incontinence, because the link between prolapse and levator avulsion defect was not widely The Royal Australian and New Zealand College of Obstetricians and Gynaecologists The Australian and New Zealand Journal of Obstetrics and Gynaecology

2 Why some cannot contract their pelvic floor muscles understood at the commencement of their study. Therefore, this study includes all women with pelvic floor dysfunction (i.e incontinence and/or prolapse) and aims to detect levator avulsion defect in all those who cannot contract their PFM after physiotherapy. Materials and Methods Women who presented to a tertiary urogynaecological centre between June 2009 and March 2012 with symptoms of urinary incontinence prolapse were included. All women underwent a standard urogynaecological history. An obstetric history, including prolonged second stage, was also recorded. Clinical assessment of the PFM strength was performed, a modified Oxford score 12 of zero was given for no palpable contraction, whilst a score of 1 was given for a weak flicker only. Exclusion criteria were as follows: a main complaint of voiding dysfunction, pelvic pain, recurrent urinary tract infection, pelvic or disseminated malignancies and neurological disorders. Furthermore, women who were virgo intacta or declined vaginal examinations for any reasons (such as menstruation or cultural issues) were not recruited. Women with severe prolapse (i.e procidentia) that required immediate ring pessary insertion or those who chose surgical intervention were also not recruited, as they were not suitable for PFM physiotherapy. Of the women who were suitable for PFM physiotherapy, those who were unable to contract at the first visit were included in the study cohort (Fig. 1). As shown in Figure 2, all eligible women were referred to subspecialty pelvic floor physiotherapists. Women who had difficulty with language and those who were not willing to have a vaginal examination by the trained physiotherapists could not be recruited. Figure 1 Flow chart of all new patients presenting with urinary incontinence and/or pelvic organ prolapse and identification of patients with Oxford score of 0 1 at initial assessment. Women who had undertaken specialised continence physiotherapy by one of the prescribed physiotherapists, yet remained unable to contract their PFM, were identified and termed noncontractors. These women were invited to participate in a transperineal ultrasound to determine the status of their PFM. Transperineal ultrasound was performed using GE Kretz Voluson 730 expert system (GE Kretz Medizintechnik, Zipf, Austria) with RAB 8-4 MHz transducer by the second author, a senior research fellow with prior ultrasound in two tertiary centres, assisted by the first author. Ultrasound imaging was performed with patient in supine position after bladder emptying, as previously described. 13 Participants were instructed to perform three PFM contractions as well as three Valsalva manoeuvres; ultrasound volumes for maximal PFM contraction and maximal Valsalva were used for ultrasound analysis. Integrity of the puborectalis muscle or levator muscle attachment was assessed with tomographic ultrasound imaging (TUI). Using TUI, the puborectalis muscle complex was imaged in its entirety within the set of eight slices at 2.5 mm slice intervals, obtained at maximal PFM contraction (Fig. 3a). Diagnosis of levator avulsion was established using the minimum criteria 14 that have been validated by comparison with MRI. 15 Using this criteria, the central three slices with the reference slice, (as shown in Fig. 3a as slice *), at the plane of minimal hiatal dimensions, that is the shortest distance between the inferior posterior symphyseal margins to the anterior border of the puborectalis muscle and the two cranial slices (2.5, 5 mm) were analysed. A complete levator avulsion (as shown in Fig. 3b) was diagnosed if all three central slices showed an abnormal puborectalis muscle attachment, whilst a partial defect is diagnosed if only one of the three central slices were abnormal or if any abnormal puborectalis muscle attachment is seen in slices three to eight of the puborectalis muscle image on TUI. 14 Levator hiatal area (highlighted by circumferential dots in Fig. 4) was assessed using methods previously described 16 for evidence of hiatal ballooning (excessive distension of the levator hiatus). A hiatal area of >25 cm 2 was considered abnormally distended, as per Dietz et al. 17 This study was approved by Human Research Ethics Committee (ref 07/73). Statistical analysis was performed using Prism version 6.0b (GraphPad Prism version 6.0b for Mac, GraphPad Software, La Jolla, CA, USA, www. graphpad.com). Normality was assessed by D Agostino- Pearson omnibus test. Mann Whitney U test was used for statistical analysis of continuous nonparametric data. Fisher s exact test was used for categorical data. A P < 0.05 was considered statistically significant. Results During June 2009 and March 2012, there were 685 new patients, of whom 60 were not eligible for recruitment (summarised in Table 1), leaving 625 with a main 2013 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists 575

3 S. Kim et al. Figure 2 Flow chart of patients with Oxford score of 0 1 who were referred to physiotherapy and those who were still unable to contract after physiotherapy. (a) (b) Figure 3 Tomographic ultrasound image of the puborectalis muscle in its entirety, at maximum pelvic floor muscle contraction. (a) is the tomographic image of a normal puborectalis muscle attachment (i.e no evidence of a levator avulsion). The three central slices assessed for levator avulsion are as follows: slice 3, reference slice marked with asterisk, slice four and five (2.5 mm and 5 mm cranial to the reference slice). (b) is an image of bilateral levator avulsion injury where defects are indicated by asterisks. complaint of either urinary incontinence prolapse. Women who had severe prolapse requesting a ring pessary at the initial visit (5%) or who declined vaginal examination (2%) were excluded. Women who were virgo intacta (0.3%) or patients whose files were missing (0.3%) were not studied (Fig. 1). Of the remaining 581 women, 150 (24%) were identified at the initial visit who had a modified Oxford score of 0 1. Within this group, 19 women were not recruited: because (i) they chose to subsequently have a ring pessary without considering physiotherapy (6%), (ii) they opted for surgery immediately (2%) and (iii) they declined physiotherapy pelvic assessment or had a language barrier which precluded optimal physiotherapy training (5%). Thus, a total of 131 women were appropriately referred for physiotherapy; of these, only 105 attended the physiotherapist (see Fig. 2). After PFM training, 85 of 105 (81%) women responded to treatment and were able to contract their PFM following a median of 3 (IQR 2 4) physiotherapy sessions. The 20 of 105 (19%) women who were unable to contract their PFM despite similar training were invited to participate in a 4-dimensional transperineal ultrasound. Of these, eight were not recruited: three declined due to medical issues (too unwell to travel), two were overseas and three were not interested in the study. Therefore, 12 women consented to participate in our study. Their demographic features are shown in Table The Royal Australian and New Zealand College of Obstetricians and Gynaecologists

4 Why some cannot contract their pelvic floor muscles (a) (b) Figure 4 Image of the pelvis on midsagittal (a) with the plane of minimal hiatal dimension as identified within the region of interest box. Symphysis pubis as indicated, B = bladder. Image (b) represents the plane of minimal hiatal dimension on axial plane, where levator hiatal area as indicated by circumferential dots. Levator hiatal ballooning (i.e excessive distensibility) is defined as follows: mild ( cm²), moderate ( cm²), marked ( cm²), severe (40+ cm²). 17 Table 1 Exclusion criteria Exclusion criteria Number (n = 59) Voiding dysfunction Pelvic pain 25 Recurrent urinary tract infection 10 Neurological disorders 22 Malignancies 2 Table 2 Demographic data of sample (n = 12) Median Parameters (IQR) Age (years) 65 (57 79) BMI (kg/m²) 33 (30 35) Parity 1.5 (1 3) Main complaint Mixed incontinence 5 (41.7%) Urge incontinence 3 (25.0%) Mixed incontinence and prolapse 3 (25.0%) Prolapse 1 (8.3%) Mode of delivery Nulliparous 1 (8.3%) Caesarean section only 1 (8.3%) Caesarean section and vaginal delivery (forceps) 1 (8.3%) Vaginal delivery 9 (75.1%) Forceps use 4 (40%) Prolonged second stage labour 4 (40%) Previous prolapse surgery 2 (16.7%) Prolapse on examination Anterior compartment prolapse 5 (41.7%) Posterior compartment prolapse 8 (66.7%) Apical compartment prolapse 2 (16.7%) Ultrasound results: Levator trauma was diagnosed in eight (66.7%) women; four complete (two bilateral, two unilateral) and four partial defects. There was no levator avulsion seen in women who were nulliparous or those who had previous caesarean section delivery. The demographic data showed no statistically significant differences between those with and without levator ani muscle defects (Table 3); however, the largest birth weights tended to be greater in those with avulsion defects. Although the numbers assessed were small in both groups (those with and without levator avulsion), we performed statistical analysis to ensure that there were no large trends evident that may confound our interpretation. Levator hiatal area on Valsalva was also assessed in all women who attended for transperineal ultrasound scan. One woman was unable to perform an adequate Valsalva manoeuvre during 3DUS; thus, only 11 volume data sets were available to assess levator hiatal area. Levator hiatal ballooning (i.e Hiatal area > 25 cm 2 ) was seen in 7 of 11 (64%) patients, and of these, 6 of 7 (86%) had levator ani muscle defects. Levator hiatal area measurements were assessed for normality using D Agostino-Pearson omnibus test. The mean levator hiatal area in all patients was cm² (range, , Table 3). The hiatal area for the two subgroups tended to be larger in women with avulsion defects (Table 3). Discussion In women with incontinence and prolapse, the ability to perform PFM contraction is essential to successful conservative treatment. In this study, we were surprised to 2013 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists 577

5 S. Kim et al. Table 3 Comparison of noncontractors with levator avulsion defect and without levator avulsion trauma Parameters (n = 12) Age (years), median (IQR) BMI (kg/m²) median (IQR) Avulsion defect (n = 8) No defect (n = 4) P value 59.5 (54 76) 74.0 (64 84) ( ) ( ) Parity median (IQR) 2.5 (1 4) 1.0 (0 3) 0.21 Weight of largest baby (kg) median (IQR) ( ) ( ) Previous forceps use (sum) Prolonged second stage labour (sum) Previous prolapse surgery (sum) Levator hiatal area (cm²) median (IQR) ( ) ( ) BMI, Body mass index. Median values of age, BMI, parity, weight of largest baby and levator hiatal dimensions were compared using Mann Whitney U test. Categorical data were compared using Fisher s exact test. P values are shown to represent the result of comparison. find that 150 of 581 (26%) women could not contract initially. As expected, the vast majority of these were able to contract after specialist physiotherapy (81%). Hence, our results show that a pessimistic view is not warranted in the majority of these women. To our knowledge, our study is the first report of a cohort of all women with pelvic floor dysfunction who were unable to contract their PFM despite physiotherapy in whom the integrity of their puborectalis muscle attachments was assessed using transperineal ultrasound. One weakness of our study is the small sample size. The population of Sydney is extremely mobile, and with a vast geographical spread, the number of women returning for follow-up was limited. Despite this, most women who were physically able to attend were strongly interested to participate in this study. Furthermore, the small number of women who were eligible for this study was derived from a cohort of women who are unable to perform PFMC despite specialised pelvic floor physiotherapy intervention. From this perspective, we feel that specialised PFMT with a trained physiotherapist is an effective intervention for a large proportion of women. A second weakness of our study is the lack of comparison with a control group. We decided to assess women who were acontractile following pelvic floor physiotherapy and evaluated integrity of the pelvic floor muscles in this group. Unfortunately, due to the increased burden on resources and confines of our ethics application, we were unable to evaluate the pelvic floor muscles of women who were able to contract their pelvic floor muscle after successful pelvic floor physiotherapy. In our current study, we have found an association between major pelvic floor trauma and the inability to perform a PFM contraction. Our results are consistent with those of Steensma et al. 18 who evaluated women with pelvic floor dysfunction [prior to any physiotherapy treatment] and found that 54% of 186 women with weak of absent PFM contraction had levator avulsion compared with 16% of 149 who were able to contract their PFM. At present, the mechanism whereby 33% of women who are unable to contract their pelvic floor muscle despite normal pelvic floor anatomy is not yet understood. The possibility that such women cannot command a pelvic floor muscle contraction by way of inadequate signalling from the central nervous system could perhaps be investigated using functional MRI studies, such as those described by Griffiths et al. 19 Alternatively, research into genetic or histological aspects of pelvic floor muscle contractility in such women may be indicated. References 1 Hagen S, Stark D, Glazener C et al. 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6 Why some cannot contract their pelvic floor muscles 13 Dietz H. Pelvic floor ultrasound: a review. Am J Obstet Gynecol 2010; 202: Dietz H, Bernardo M, Kirby A, Shek K. Minimal criteria for the diagnosis of avulsion of the puborectalis muscle by tomographic ultrasound. Int Urogynecol J 2011; 22: Zhuang R, Song Y, Chen Q et al. Levator avulsion using a tomographic ultrasound and magnetic resonance based model. Am J Obstet Gynecol 2011; 205: 232 e Dietz H, Wong V, Shek K. A simplified method for determining hiatal biometry. Aust N Z J Obstet Gynaecol 2011; 51: Dietz H, De Leon J, Shek K. Ballooning of the levator hiatus. Ultrasound Obstet Gynecol 2008; 31: Steensma AB, Konstantinovic ML, Burger CW et al. Prevalence of major levator abnormalities in symptomatic patients with an underactive pelvic floor contraction. Int Urogynecol J 2010; 21: Griffiths D, Tadic SD. Bladder control, urgency, and urge incontinence: evidence from functional brain imaging. Neurourol Urodyn 2008; 27: The Royal Australian and New Zealand College of Obstetricians and Gynaecologists 579