November 2005

Biofeedback vs Electrophysiology

By Howard I. Glazer, PhD

Surface electromyography is becoming the standard treatment of lower urogenital tract pain disorders

Figure 1. Pelvic floor muscle sEMG from asymptomatic patient showing low stable resting tone with short recruit/recover latencies to high amplitude, low variability, and high spectral frequency tonic contractions.

It was not until the early 1990s that pelvic floor muscle surface electromyographic (sEMG) biofeedback diversified from its initial applications—pelvic support and voiding disorders—to its most recent application in the field of lower urogenital tract pain disorders. The first peer-reviewed publication using sEMG-assisted rehabilitation of pelvic floor musculature in the treatment of vulvovaginal pain was titled "Treatment of Vulvar Vestibulitis Syndrome with Electromyographic Biofeedback of Pelvic Floor Musculature."¹

This study demonstrated a slightly more than 50% asymptomatic outcome rate and an average improvement of 83% with 80% of sexually abstinent patients resuming regular intercourse. This study also reported that only changes in the standard deviation of the resting sEMG signal predicted pain change. This finding confirmed anecdotal clinical experience that the treatment is essentially an sEMG stabilizing program. This paper also concludes that the response to this therapy suggests that whatever the etiologic factor—infection, dermatoses, trauma, hormonal—vulvar vestibulitis syndrome may be a result of autonomically mediated pain. This mechanism, as a final common pathway for multiple etiologies, may explain the lack of consensus on a single antecedent despite consistency in symptomatology of the syndrome. A critical factor emerging from this study differentiates this treatment from previous applications of pelvic floor muscle biofeedback.

Previous pelvic viscera support and voiding dysfunction applications of sEMG biofeedback focus on increasing contractile amplitude (strengthening) and reducing resting amplitude (relaxation). This application focuses on reducing sEMG variability or electrophysiologically stabilizing the muscle. Previous applications of biofeedback for treating pelvic floor muscle related disorders viewed the symptom, prolapse, incontinence, or retention, as a direct consequence of pelvic floor muscle dysfunction, weakness, or hypertonicity. Thus, strengthening and/or relaxing the muscle was the primary focus. In vulvovaginal pain disorders, the muscle is not viewed as the source of the pain disorder. Vulvar vestibulitis syndrome is not a myofascial pain disorder. The pelvic floor muscle dysfunction is viewed as a nonetiologic mediating factor in the maintenance of a chronic reflex sympathetic dystrophy, now known as chronic regional pain syndrome type of mechanism.

This initial finding sets the stage for a significant shift away from simply strengthening or relaxing pelvic floor muscles in which the sEMG signal is viewed as almost incidental, just providing more sensitivity and convenience than digital palpation or manometrics, toward a much greater emphasis on characteristics of the sEMG signal itself. Significant technological advances in sEMG signal processing hardware and software in the past decade have also contributed the necessary underpinnings for the further advancement of this work. Unlike using sEMG as an approximation of muscle tone or strength, when measuring sEMG signal variability, signal processing becomes paramount. Factors such as analog to digital conversion rate, mathematical reintegration methodology, band pass and notch filtration characteristics, signal rectification, and sensor characteristics such as size, electrical characteristics of materials, and placement are critical in determining the measurements under consideration.

Figure 2. Pelvic floor muscle sEMG from vulvar vestibulitis syndrome patient showing resting hypertonicity and instability with slow recruit/recover latencies to low amplitude, high variability, and low spectral frequency tonic contractions.

NEW WAY OF THINKING
One way to think about the new direction taken by this type of research is to see it as representing the difference between biofeedback and electrophysiology. Biofeedback historically emerges from psychology. Initially, biofeedback was a laboratory tool to study whether learning voluntary or instrumental self-regulation of viscera was possible.² Its early clinical applications were predominantly psychophysiological. Biofeedback aimed at creating or augmenting awareness of interoceptive cues and teaching the patient voluntary regulation of biological processes in order to reduce or alleviate symptoms arising from dysfunctional psychological states such as anxiety. For example, biofeedback could be used as a process for changing the peripheral expression of sympathetic dominance, eg, blood pressure, skin conductance, muscle tension, or respiration, through direct self-regulation training.

In this way, adverse biological and psychological consequences of chronic stress such as hypertension, excessive sweating, tension headaches, hyperventilation, and emotional distress could be alleviated. This traditional application of biofeedback in clinical practice is a highly subjective, experiential, individualized, and patient-focused process, typical in the clinical practice of psychology. Electrophysiology, including electromyography, emerges historically from technologies such as biomedical engineering.³ Traditional in these fields is an emphasis on scientific methodology represented by highly evolved technology with well operationally defined, objective, reliable, and valid measurements and highly standardized or protocolized applications of these measurements. This approach typically includes the development of large sample databases representing normative and pathology-specific patient status for the purpose of diagnosis and treatment selection. Electrocardiology, electroencephalography, and needle EMG are examples of medical electrophysiology. Medical devices and their measurement technology and protocols are typically standardized leading to the development of large statistically parametric databases used to accurately and reliably define pathology in the tissue under measurement.

This differentiation between biofeedback and electrophysiology has led me to look at pelvic floor muscle sEMG in an entirely new light. In reviewing patient history and sEMG data, I was limited to asking "Is this patient relaxed or tense? Weak or strong? and should I uptrain or downtrain to alleviate symptoms of prolapse, retention, or involuntary loss?" Now I ask: "What equipment and software produced this data? What are the signal processing characteristics? What data collection protocols were used? What are resting and contractile signal amplitudes and variability? What are the contractile recruitment and recover latencies, coefficients of variation, Fast Fourier Transformed (FFT) power density spectral frequencies, amplitude/variability coefficients, successive tonic and endurance contraction percentage amplitude declines? (See Figures 1 and 2 for examples of normal and pathological pelvic floor sEMG tracings.) Each patient's pelvic floor muscle sEMG findings are added to a database of operationally defined normative or lower urogenital tract dysfunction groups. Parametric group differences and regression analyses are applied to the data to develop sEMG profile characteristics that significantly differentiate each dysfunction from other dysfunctions and normals. These pathology-defining sEMG characteristics can then be used to develop disorder-specific pelvic floor muscle rehabilitation protocols. Each new patient is both added to the database and compared to the database, which is then used to assist in the diagnosis of the disorder and the determination of a specific muscle rehabilitation protocol.

DEFINING THE APPROACH
This electrophysiological approach is defined by the use of highly sophisticated and standardized sEMG equipment and software, standardized data collection protocols, and the development of large-sample, pathology-specific sEMG databases for improved diagnostic accuracy and treatment efficacy. I have found this approach to be incredibly productive for both clinical research and patient treatment. Since the publication in 1995 of the article discussed above, a sample of what this approach has yielded includes:

1. Data challenging the traditional minimization of accessory muscles during the conduct of sEMG-assisted pelvic floor muscle rehabilitation.⁴

2. The establishment of pelvic floor muscle sEMG criteria for the diagnosis of vulvar vestibulitis syndrome.⁵
3. Establishing pelvic floor sEMG database norms for the diagnosis of dysesthetic vulvodynia.⁶
4. Establishing pelvic floor muscle sEMG as statistically reliable and valid in identifying clinical status variables.⁷
5. Establishing the superiority of pelvic floor muscle sEMG over standardized digital palpation in the identification of pelvic floor muscle dysfunction.⁸
6. Demonstration of the long-term maintenance of therapeutic benefit of pelvic floor muscle sEMG assisted rehabilitation in the treatment of dysesthetic vulvodynia.⁹
7. A replication of the 1995 Glazer study using pelvic floor sEMG rehab in the treatment of vulvar vestibulitis syndrome demonstrating higher, 84.7% successful outcome.¹⁰
8. Study demonstrating pelvic floor sEMG changes resulting from botox injections can predict therapeutic benefit in the treatment of vulvar vestibulitis syndrome.¹¹
9. Study, in press, demonstrating pelvic floor muscle sEMG can assist in the diagnosis and treatment of chronic pelvic pain syndrome (CPPS) in men.¹²

In summary, I would urge all practitioners of pelvic floor muscle sEMG biofeedback to consider blending this more technical and scientific electrophysiology approach with their existing clinical treatment expertise to further advance their own clinical practice skills and to advance the cause of greater acceptance of pelvic floor sEMG into traditional medical practice. For example, I believe that all women should have a pelvic floor assessment annually for early detection and prevention of prolapse, incontinence, and loss of sexual function, just as they would have an annual mammogram. The best way for clinicians to upgrade their skills is to take a course approved by the Biofeedback Certification Institute of America (BCIA) in preparation for the BCIA examination for subspecialty certification in Pelvic Muscle Dysfunction Biofeedback.

Howard I. Glazer, PhD, is a clinical associate professor of psychology in psychiatry at Weill College of Medicine, Cornell University, New York Presbyterian Hospital, New York.

REFERENCES

1. Glazer HI, Rodke G, Swencionis C, Hertz R, Young A. The treatment of vulvar vestibulitis syndrome with electromyographic biofeedback of pelvic floor musculature. J Reprod Med. 1995;40:283-290.
2. Miller NE. Biofeedback and visceral learning. Annual Review of Psychology. 1978;29:373-404.
3. Tarlar-Benlolo L. The role of relaxation in biofeedback training: a critical review of the literature. Psychol Bull. 1978;85:727-755.
4. Glazer HI, MacConkey D. Functional rehabilitation of pelvic floor muscles; a challenge to tradition. Urologic Nursing. 1996;16(2):68-69.
5. White G, Jantos M, Glazer HI. Establishing the diagnosis of vulvar vestibulitis. J Reprod Med. 1997;42:157-161.
6. Glazer HI, Jantos M, Hartmann E, Swencionis C. Electromyographic comparisons of the pelvic floor in asymptomatic and vulvodynia females. J Reprod Med. 1998;43:959-962.
7. Romanzi L, Polaneczky M, Glazer HI. A simple test of pelvic muscle during pelvic examination: correlation to surface electromyography. Journal of Neurourology and Urodynamics. 1999;18:603-612.
8. Glazer HI, Romanzi L, Polaneczky M. Pelvic floor muscle surface electromyography; reliability and clinical predictive validity. J Reprod Med. 1999;44:779-782.
9. Glazer HI. Dysesthetic vulvodynia. Long term follow-up after treatment with surface electromyography-assisted pelvic floor muscle rehabilitation. J Reprod Med. 2000;45:798-802.
10. McKay E, Kaufman R, Doctor U, et al. Treatment of vulvar vestibulitis with electromyographic biofeedback of pelvic floor musculature. J Reprod Med. 2001;46:4:337-347.
11. Brown CS, Ling F, Johnson K, Vogt V, Glazer H, Wan J. Predictors of treatment response in a self-report survey of patients with vulvodynia [abstract]. Obstet Gynecol. 2003;101(4 suppl):56S.
12. Hetrick DC, Glazer H, Liu Y, Turner J, Frest M, Berger RE. Pelvic floor electromyography in men with chronic pelvic pain syndrome: a case-control study. Journal of Neurourology and Urodynamics. In press.

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