Gordon White, F.A.C. Ven., M.H.P, M.F.P.H.M., Marek Jantos, M.A., and Howard Glazer, Ph.D.

OBJECTIVE: To study the pelvic floor electromyographic (EMG) responses of a cohort of patients diagnosed with vulvar vestibulitis.

STUDY DESIGN: Following full medical and laboratory workup, patients with vestibulitis were given pelvicb floor EMG. Results were compared with the collated data, termed the "nonmorbid EMG pelvic floor response, derived from a study control group of 50 symptomless subjects. Six aspects of the EMG response were examined: resting baseline, contractile potential, resting standard deviation, recruitment, recruitment recovery and power spectral analysis.

RESULTS: As compared to the study control group, the cohort demonstrated elevated resting baseline above 2.0 uV in 23 (71 %); poor contractile potential, < 17 uV, in 20 (65%); elevated resting standard deviation, > 0.20, in 30 (93%); slow to poor recruitment recovery after contraction, >0.2 seconds in 27 (86%) and low frequency, < 115 Hz in 22 (69%).

CONCLUSION: The study confirmed that of vestibulitis patients, 88% will show at least three of the above altered criteria and that the diagnosis can be confirmed by: (1) the instability of muscle, (2) poor muscle recovery after contraction, and (3) elevated resting baseline plus one other optional criterion, either (4) reduced frequency or (5) reduced muscle contraction strength.

(J Reprod Med 1997;42:157-160)

Keywords: vulvar diseases, vulvar vestibulitis.

Introduction

An increasing number of women present with severe vulvar pain on sexual penetration and tampon insertion and removal. Women diagnosed with vestibulitis and participating in various sporting activities experience pain wearing tight clothing. In fact, pressure of any nature against the vestibule produces pain and discomfort. Frequently patients have other associated symptoms-sensations of swelling, dryness, vulvar burning (vulvodynia)1, pruritus and urinary frequency.

Examination using a cotton-tipped applicator elicits pain around the vestibule close to but just distal from the hymen. Patients can perceive tenderness around the vestibule, sometimes on both sides and often at the 4 and 8 o'clock positions. Digital examination will often elicit pain in the vicinity of the pubococcygeus muscle and base of the bladder.

The diagnosis [of vestibulitis]
can be confirmed by
electromyographic readings in
the presence of at least three
essential characteristics ....

No etiology for the vestibulitis syndrome2 has been recognized, although an inflammatory infiltrate has been confirmed composed of a mixed population of T lymphocytes, monocytes and occasional plasma cells.3 The minor vestibular glands are never directly involved by inflammation.

Patients with symptoms suggestive of vulvar vestibulitus but
who do not satisfy the EMG characteristics should be reviewed
carefully to exclude ... other causes....

Recent hypotheses suggest that these conditions are neurophysiologic responses rather than somatic pain and that they are sympathetically mediated.4,5

Since the principal motor and sensory nerve fibers of both the vulva and pubococcygens muscle are branches of the pudendal nerve plexus, containing fibers from S3 and S4, it is hypothesized that superficial vulvar and vestibular irritability destabilize the musculature of the pelvic floor. This is reflected in the electromyographic (EMG) recordings of the muscles that are within the pain reference zone of such disturbed tissue.6,7

Methods

A cohort of 32 white women presenting to our unit with symptoms of typical vestibulitis both with and without vulvodynia were assessed against specific criteria and an accurate clinical diagnosis made. The results are set out below in Table 1.

Subsequently an EMG assessment of the pelvic floor was carried out using a single-user vaginal sensor (T6050, Thought Technology Ltd., Montreal, Quebec, Canada).

Table 1 Clinical Criteria of the Cohort

N = 32.

and a computerized EMG analysis using the Glazer Pelvic Muscle Rehabilitation Program, Version 2.2 (Biobehavioral Medical Rehabilitation Inc., Jacksonville, Florida). The sensor is designed to accurately monitor and "feedback" EMG activity of the pelvic floor musculature. The surface electrodes of the vaginal sensor detect gross EMG signals that correlate 0.99% with data produced by invasive fine wire stainless steel electrodes.8

To date there are no age group or other published normative data for EMG recordings of pelvic floor musculature in women. Such information is currently being collected. Current baseline data were derived from results in a group of 50 subjects derived from the following sources: (1) patient outcome responses after treatment with EMG, and (2) limited number of assessments of women without signs or symptoms of vestibulitis/vulvodynia. We have termed this assumed standard "nonmorbid EMG pelvic floor response."

The nonmorbid EMG response of the 50 subjects was derived as follows:

Resting potential. This is the mean integrated EMG root mean square (rms) measured over six 12-second rest periods alternated with six 12-second contractions. In 82% of subjects this was found to be <2.0 uV.

Contractile potential. This is the mean of six 12-second, contraction-integrated EMG rms with 12-second rest periods between each contraction. This was found to be > 17.5 uV in 87% of subjects.

Resting standard deviation. This is the mean of the standard deviations of the integrated EMG rms for six 12-second rest periods. It was found to be <0.2 in 79% of subjects.

Recruitment. This is the time in seconds for an integrated EMG rms amplitude to go from the resting baseline to 80% of contraction average with voluntary contraction. In 99% of subjects this was <0.2 seconds.

Recruitment recovery. This is the time for an integrated EMG rms amplitude to return from at least the 80% state of voluntary contraction to the state of baseline relaxation. This was assessed to be <0.2 seconds in 94% of subjects.

Frequency. This is the mean power density spectral analysis of integrated EMG rms for six separate 12-second contraction periods with 12-second rest periods between each contraction and was estimated to be >115 Hz in 88% of subjects. A typical graph of such a subject is shown in Figure 1.

Figure 1 Typical nonmorbid EMG pelvic floor responses. Characteristics: (1) low resting baseline with good muscle stability, (2) good recruitment with clear demarcation between rest and contraction, (3) strong contraction with no fatigue (sustained contraction), (4) abrupt fall from contraction to resting baseline (relaxation), and (5) low resting baseline with good muscle stability after contraction.

Results

This cohort of women had an average age of 33 years with a duration of vestibulitis symptoms of 33 months (range 3-240). Fourteen patients reported a past history of sexually transmitted disease (herpes genitalis 5, human papillomavirus infection 8, pelvic inflammatory disease 1, syphilis 1 and cervical intraepithelial neoplasia 2). The average number of reported sexual partners was 7, with a range 1-35. The average age at the first sexual experience was 17.8 years, and 9 patients reported sexual trauma or abuse as children. All patients reported pain at intercourse, and the assessed rating, on a scale of 0-10, was 7.3. Twenty-seven patients experienced some genital pain with orgasm; the average severity of pain on the 0-10 scale was 6.8. Most patients (97%) had had a history of genital candidiasis, while 70% reported having experienced premenstrual tension.

Table II sets out the EMG responses of the 32 patients clinically diagnosed with vestibulitis. The resting baseline was found to be elevated due to hypertonicity of the muscle bundles in 23 patients (71%), and the contractile potential in 20 (65%) was poor due to muscle fatigue. The resting standard deviation was high (>0.20) in 30 patients (93%), indicating muscle instability, while recruitment recovery after contraction was slow (>0.2 seconds) in 20 patients (86%), and the frequency was low, <115 Hz, in 22 (69%).

Table ll EMG Response in the Study Cohort

N=32.

Eighty-eight percent (88%) of patients with a clinical diagnosis of vestibulitis satisfied at least three or more of these abnormal EMG criteria. Figure 2 shows a typical graph from a patient with vestibulitis.

The applicability and use of this form of analysis can be seen from the following history of a patient not included in this study cohort. A 32-year-old woman was referred to our unit having had a six-month history of genital discomfort with a clinical assessment suggesting point tenderness, vulvar burning, pain on penetration, clear vaginal discharge and urinary frequency. Initially the picture suggested a diagnosis of vulvar vestibulitis. Routine medical assessment was carried out, including laboratory testing, and EMG was performed.

Figure 2 Pelvic EMG activity for typical vulvar vestibulitis.

Characteristics: (1) elevated and unstable resting baseline, (2)poor recruitment, (3) spasm on sustained contraction and fatigue, (4) poor recovery, and (5) post contraction baseline remains elevated, with high amplitude and instability.

The results of the EMG assessment were as follows: resting baseline 0.57 uV, muscle stability with a 0.15 standard deviation, contraction strength 41.39 uV, recruitment recovery 0.2 second and frequency 125 Hz. These data indicated a nonmorbid EMG response in comparison with our baseline data. Laboratory assessment of the vaginal and cervical mucus showed a marked overgrowth of lactobacilli with minimal inflammation and a few white blood cells. The pH was acidic, 4.0, and there were no organisms or yeast cells. Ragged epithelial cells were present, with some free nuclei. The picture was consistent with that described by Cibley and Cibley9 and termed "cytolytic vaginosis." The patient was treated for seven days with once-daily pessaries containing di-iodohydroxyquinoline, 100 mg; boric acid, 65 mg; and phosphoric acid, 17 mg together with twice-daily sodium bicarbonate genital bathing (30-60 g/L of warm water), resulting in a rapid and uneventful recovery. The EMG study was not repeated on account of nonmorbid readings at the outset. Vaginal cytology returned to normal after two weeks, when all genital symptoms abated.

Discussion

Our study indicated that the following five EMG variations from the non-norbid EMG pattern were common to our cohort of vestibulitis patients: muscle instability at rest, poor muscle recovery, elevated resting baseline, reduced (muscle activity) frequency and reduced contraction strength (potential). The sixth criterion tested (poor recruitment of muscle bundles) was found to be of little diagnostic value.

The study showed that 88% of vestibulitis patients will show three or more of the above criteria, thus suggesting that the diagnosis can be confirmed by EMG readings in the presence of at least three essential characteristics: (1) instability of muscle, (2) poor muscle recovery after contraction and (3) elevated resting baseline plus one other optional criterion, either (4) reduced frequency, or (5) reduced muscle contraction strength.

Patients with symptoms suggestive of vulvar vestibulitus but who do not satisfy the EMG characteristics should be reviewed carefully to exclude what could perhaps be other causes of vulvar and vaginal irritation and discomfort.

Acknowledgments

The authors wish to acknowledge the permission given for this study by the Ethics Committee, Department of Health and Community Services, Australian Capital Territory.

References

1. Freidrich EG: Vulvar vestibulitis syndrome. J Reprod Med 1987;32:110-114

2. McKay M: Vulvodynia: A multifactorial clinical problem. Arch Dermatol 1989;125:256

3. Pyka RE, Wilkinson EJ, Friedrich EG, et al: The histopathology of vulvar vestibulitis syndrome. Int J Gynecol Pathol 1988;7:249-257

4. Lynch PJ: Vulvodynia: A syndrome of unexplained vulvar pain, psychologic disability and sexual dysfunction. J Reprod Med 1986;31:773-780

5. Cox JT: Deconstructing vulval pain. Lancet 1995;345:53

6. Travell J, Simons D: Myofascial Pain and Dysfunction: The Trigger Point Manual. First volume. Baltimore, William & Wilkins, 1983 7. Glazer HI, Rodke G, Swencionis C, et al: Treatment of vulvar vestibulitis syndrome with electromyographic biofeedback of pelvic floor musculature. J Reprod Med 1995;4:283-290

8. Binnie NR, Kawimbe BM, Pfapachrysostomou N, et al: The importance of the orientation of the electrode plates in recording the external anal sphincter EMG by noninvasive anal plug electrodes. Int j Colorect Disease 1991;6:5-9

9. Cibley Lj, Cibley Lj: Cytolytic vaginosis: A common cause of vaginitis. In Vaginitis and Vaginosis. Edited by Bj Horowitz, PA Mardh. New York, Wiley-Liss, 1991, pp 181-185