Thursday, October 6, 2016

Mucosal versus muscle pain sensitivity in provoked vestibulodynia Witzeman K, Nguyen R, Eanes A, Sawsan S, Zolnoun, D. Journal of Pain Research 2015:8 549-555

Elizabeth Lewis, PT, OCS, WCS, 10/5/16

Pelvic PT distance journal club

Aim: To understand and compare the relative contribution of mucosal versus muscle pain sensitivity with intercourse as reported from women with  provoked vestibulodynia (PVD).


 Estimated that 8.3%-16% of women experience vulvovaginal discomfort in their lifetime and for many, it’s provoked on contact, commonly referred to as  provoked vestibulodynia (PVD).

Little is known about the etiologies: PFM dysfunction and mucosal components, Or how abnormalities in muscle form or function may impact pain during intercourse. 

And, more information is needed on the relationship of mucosal sensitivity to PFM contracture/hypertonicity and potential pain and vice versa.

Subjects:. 54 women, primarily college educated (80%), married (87%), white women (84%) aged 31 years, of whom 81% were nulliparous

 Subjects and data were taken from an original study of 196 eligible women diagnosed with VVS during or after January 2002.   Of these, 137 (70%) completed the questionnaires and only 54 women met the inclusion/exclusion criteria (see study).

 Methods:  Proof of concept study nested in a previous study of PVD : Cross-sectional questionnaire study,  done between February 1, 2003 and October 31, 2005 and  approved by the institutional review board at the University of North Carolina at Chapel Hill.   Initial study used  3-4 questionnaires including assessments for psychological characteristics and self-reported .  The current study only used data from one: the Gracely scale.

Then the 54 were selected and given the physical exam.

The physical exam included two tests to determine pressure pain thresholds (PPT):  a cotton swab test of for vaginal mucosal sensitivity and also a pelvic floor muscle test using a modified Jaeger’s technique pressure algometer .

Two independent reviewers abstracted the data from the exam and history from the medical records. 

They divided the group into two phenotypes of primary or secondary PVD.  They were masked to the subject’s questionnaire responses.  High agreement:  out of 54 subjects, 20 had primary PVD and 32 had secondary and 2 couldn’t be classified.

Mucosal sensitivity exam was described as a standardized approach (ref 18)  to palpation and localization of individual mucosal sites of the vestibule. 

Six spots with the clock reference: 3 anterior: 10:00, 12:00 and 2:00 and 3 posterior, which mirror the anterior.

 Anterior points of 2 and 10:00 found using anatomical landmarks of a horizontal line through the urethral meatus and 12 as being midpoint between the clitoris and the urethral meatus.  Site 6:00 was most posterior.

Due to previous work with an algometer they reportedly used pressure with a cotton swab corresponding to 1-1.5 Newton at each site.  Pressure was applied for about 1 and released for 2 seconds They began with anteriorly then posteriorly: R, L then midline. 

Following each palpation, the patient rated it on the 0-10 Likert scale and the three points were averaged for both the anterior then posterior regions.

Pelvic Muscle PPT measurements were taken with a modified Jaeger’s technique using the index finger pressure calibrated with an algometer to an increment of 500g/s.  Pressures vary from 500 g to up to 3,000 g to assess muscle pain in the pelvic floor.  Three muscle groups were assessed: 1)- Perineal: posterior fibers of Bulbocavernosus converging with central midline of Transverse Perineal at 6:00 and 2,3)- Right and Left Puborectalis , located <.5 cm adjacent/behind midpoint of pubic rami,  and 1-1.5 cm posteriorly “downward”).

Participants reported the first onset of pain and the pressure was then stopped and that pressure: pressure pain threshold ( PPT) was recorded.  Each site was tested 3x and then PPT was averaged.

 For  self-reported pain with intercourse, Gracely Pain Scale was used.

Statistical analyses were done using SAS 9.1   They used Student t-tests and composite average scores to average the mucosal and muscle measures.  Pearson’s correlation was used to describe the subjective pain report with intercourse, and relate to mucosal and muscle pain.  It was also used for correlations in the subgroups of PVD.  Significance was set to (P<0 .05="" all="" comparisons.="" in="" o:p="">

Results: With the 0-10 pain scale, the average mucosal cotton swab rating was greater in the lower vestibule at 5.81 (SD = 2.83) , vs the upper, at 2.52 (SD =  2.6) (P= .01).   No difference in mucosal sensitivity between primary vs secondary PVD

Slight but only marginally significant difference  between groups, in self-reported maximal severity of pain with intercourse :primary PVD: 87.1  (SD 10.8) and secondary: 72.9, (SD=24.8 ), (P=.06)  on 0-100 scale.  

Correlation of the average mucosal pain rating for the lower vestibule and with “components” of the modified Gracely scale for all patients (r=0.38, P<.01) but there was no correlation with reported maximal or minimal pain on intercourse and the pain on physical exam, for either subgroup.

Muscle pain threshold varied at the 3 tested sites from 500-2,000 g.  The greatest sensitivity (lowest PPT as low as 500g ) values were recorded in the perineal muscle complex.  Puborectalis was also tender in this PVD population and only 4 patients reported tolerated pressures as high as in healthy women ( 2,000 g).

Women with greater muscle tenderness (lower PPT) reported more pain with intercourse : average and highest intercourse pain significantly correlated with lower PPTs on exam (r=0.46, P= 0.01 and r=0.42, P=0.02 respectively). (Figure 4)

There was a difference between the two groups in muscle tenderness but it was not significant (P= 0.15).

Weaknesses and Limitations: 1) Continuous wide range of pressure vs a set amount of pressure was given (but they said this was off-set by having one examiner with a high within subject reproducibility of 200-300g).

2) They only looked at the relationship between the “6:00 muscle” and the clinical pain report

3) They used a composite score for the “lower vestibule” averaging for areas at 5,6 and 7:00.  (They justified this due to previous study by Zolnoun).

4) there were variable results for muscle tenderness and inconsistent examination of pelvic muscles due to the tester trying to minimize emotional aversion and discomfort of the primary PVD group by using the same index finger of the R hand vs switching hands, (as with the secondary PVD group). 

5) They were limited in evaluating mucosa in parous women as often the vulvar mucosa is replaced by vaginal epithelium following childbirth.  They say the limited association between clinical pain report and mucosal sensitivity may be explained in part by this challenge in assessment.

Strengths: This study raises the question of the adequacy of relying on the one-dimensional mucosal sensitivity test for diagnosis and classification of patients with PVD.  They point out that the variance in sensitivity can also be due to neuromuscular dysfunction and hypertonicity with referred neurogenic sensitivity.  They have piloted and described a more nuanced methodology for a more multidimensional assessment of pelvic pain (that also includes a women’s report of pain).

They recommend further studies on the effectiveness of various PT techniques such as STM, MFR, Dry needling and core strengthening on muscle pain and dyspareunia.

Outcomes/Discussion: This study suggests there’s a difference between correlations between intercourse pain report and pelvic muscle vs mucosal pain sensitivity (stronger correlation with pain report and muscle sensitivity).  However, mucosal sensitivity was also correlated moderately. 

There was no difference with mucosal sensitivity between the primary and secondary PVD patient groups.

They stated they observed that the pattern of muscle and pelvic floor sensitivity differed between the primary and secondary PVD groups and that those with primary tended to be more sensitive at 5 and 7:00 and women with secondary at 6:00.  They said that since there were more women in the secondary group, the 6:00 position (Bulbocavernosus and Transverse Perineal convergence) was the most positive.

Discussion Questions:

·         Will this alter your clinical assessment of patients with PVD, if so, how?

·         How do you think the tester not changing hands with the primary PVD group might have affected the outcomes, if at all?

·         Do you think they compromised the validity of the Gracely scale by using “components” of it and if so, did that impact their outcomes?

·         What do you think about the VQ test as related to assessing for PVD?

·         What do you think about the muscles used in the study?


Questionnaires given in initial study:

Pain Questionnaire

A Gracely Pain Scale was used to assess pain.  This is the only study specifically mentioned and used in the current proof of concept study:  Women rated the lowest, average and maximal pain with intercourse on a 0-100 scale.  They selected verbal descriptors by circling a word that best described their pain including two pain domains of 1) sensory (severity of physical pain) and 2) affective (emotional response to the level of physical pain).  A predetermined numerical value for each descriptor was averaged to give a summary score for statistical analysis. 

(Modified versions of this have been used for pelvic pain, such as below: Gracely Box scale (modified version) is of 21 boxes sequentially numbered 0-20 (0 representing least amount of pain or distress) and arranged vertically in two columns to correspond with increased amounts of pain in one column or emotional distress in the other column. See reference to view modified scale, I was unable to procure 100 point scale:

 Gracely Box scale measures of pelvic pain intensity (left)... - Scientific Figure on ResearchGate. Available from: [accessed Oct 2, 2016]

Psychological Questionnaires:   administered questionnaires to assess anxiety (Speilberger State-Trait Anxiety Inventory), somatization (Pennebaker Inventory of Limbic Languidness), and global psychological distress (Brief Symptom Inventory-Global Severity Index). The following is a brief description of these questionnaires

The State-Trait Anxiety Inventory (STAI) consists of two 20-item questionnaires, which assess an individual's current anxiety level and general propensity towards anxiety.  It has good reliability and the norm for women is 36 on both scales.

The Pennebaker Inventory of Limbic Languidness (PILL) assesses somatization by capturing the frequency of occurrence of 54 common physical symptoms and sensations. It has “adequate” test-re-test reliability and high internal consistency and the norm for females is 98-104.  A high somatization score is an independent risk factor for chronic pain development and correlates with number of muscle  tenderness sites, pain sensitivity and progression to chronicity.

 The Brief Symptom Inventory (BSI) consists of 53 items rating psychological distress in nine areas including: somatization, obsessive-compulsive, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, and psychoticism.1A global severity index (GSI) is obtained by combining the number and intensity of reported symptoms.  Test-retest validity for the global severity index score is 0.90; the norm for the female population is 50, with a clinical cut-off of 63.

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