Part 4: IFT Vs. Biofeedback = Demirturk et al.

Of all the literature reviewed, one study stood out as the most valid for determining the effectiveness of Interferential Therapy (IFT) in the treatment of Urinary Stress Incontinence (USI); a study published in 2008 by Demirturk and colleagues. It directly compared IFT versus Biofeedback and Kegel exercises. 40 USI patients were randomly designated to 2 groups, one undergoing IFT and the other Biofeedback with Kegel exercises. The patients were all female with a mean age of 52 years and an average number of deliveries of 3. This represents a significant clinical population but fails to address all at risk populations of USI. Each group was prescribed 15 sessions of each protocol for 15-minutes each, over a 5-week period.

The results were found using a 1-hour pad test to detect any leakage, pelvic floor muscle (PFM) strength testing and quality of life (QoL) questionnaire. Both methods were found to be similarly effective in all the parameters tested. The figures below show the relatively similar effects of both treatments when taking into account the pre-intervention and post-intervention values.

Since no adverse effects were observed, the study concluded that the two approaches could be applied effectively in the treatment of USI. The clinical significance of these results applies to the way in which practitioners can treat their USI patients. Therapists can decide whether to use IFT or Biofeedback based on their personal preference, clinical experience and patient preferences with the confidence that both methods are effective. The advantages of IFT are its ease of usage and external application. The Biofeedback treatment may be avoided due to the relative invasiveness of the vaginal probe required.

At the end of the study, participants were recommended to perform an at-home program of Kegel exercises, to be followed up on at a later date. The results of this follow-up survey are yet to come, but would provide an interesting prognosis of the condition after each mode of treatment.

The advantages of this study were that it involved a relatively large sample size and significant intervention time. The disadvantage was that all participants were female.

The following points summarize the findings of the literature on Interferential Therapy for Urinary Stress Incontinence. Electrode placement for IFT is more effective when the anterior electrode is above the pubic bone, as per the Dumoulin method ^[2]. IFT was found to be effective in increasing PFM strength and Quality of Life and also reduced the frequency of incontinence, volume of urine loss ^[3][4]. Additionally, IFT was shown to be better suited to mild and moderate than severe USI ^[5].

Dosages, Precautions & Contraindications

To summarize the blog, the following information can be used to safely apply IFT in a clinical setting:

In order to treat the PFM the following dosage parameters are recommended: a Phase Duration of 125ms, a current of 80 mA or to patient comfort and a frequency of 2–4000 Hz with an interference current of 50 Hz.

An important precaution specific to IFT is the presence of skin conditions as the suction cups may cause irritation or further damage. Such conditions include thin, frail skin, open wounds or lesions. Also if the patient is taking anticoagulant medication or is prone to bruising, this may lead to visible marks where the suction cups had been.

A contraindication specific to IFT for the PFM is pregnancy due to the inherent electrode positioning of the treatment.

We hope you have enjoyed this blog and found it relevant to your practice.

References

1.     Demirturk, F., Akbayrak, T., Karakaya, I. C., Yuksel, I., Kirdi, N., Demirturk, F., Kaya, S., Ergen, A., Beksac, S. (2008). Interferential current versus biofeedback results in urinary stress incontinence. Swiss Medical Weekly, 138(21-22), 317-321.

2.     Dumoulin, C., Seaborne, D. E., Quirion-DeGirardi, C. & Sullivan S. J. (1995). Pelvic-floor rehabilitation, part 1: comparison of two surface electrode placements during stimulation of the pelvic-floor musculature in women who are continent using bipolar interferential currents. Journal of the American Physical Therapy Association, 75(12), 35-42.

3.     Dumoulin, C., Seaborne, D. E., Quirion-DeGirardi, C. & Sullivan S. J. (1995). Pelvic-floor rehabilitation, part 2: pelvic-floor reeducation with interferential currents and exercise in the treament of genuine stress incontinence in postpartum women – a cohort study. Journal of the American Physical Therapy Association, 75(12), 44-49.

4.     Oh-oka, H. (2008). Efficacy of interferential low frequency therapy for elderly wet overactive bladder patients. Department of Urology Kobe Medical Center Japan, 24(2), 178-181.

5.     Turkan, A., Inci, Y. & Demirturk, F. (2005). The short-term effects of physical therapy in different intensities of urodynamic stress incontinence. Gynecologic and Obstetric Investigation, 59(1), 43-48.

Part 3: The Evidence

As with all bioinstrumentation, a foundation of knowledge of the literature is needed before applying these methods to patients. The validity of Interferential Therapy (IFT) as a form of treatment for Urinary Stress Incontinence (USI) was found by critically reviewing 5 studies, the fifth of which will be discussed in a later post.

1.    Electrode Placement Methods = Dumoulin et al. (Part 1) ^[1]

This study compared two IFT electrode placement methods to maximally stimulate the PFM. Both methods involve a posterior electrode above the anus; Laycock and Green^[3] then suggest an anterior electrode on the clitoral region and Dumoulin^[2] suggest the anterior electrode should be above the pubic symphysis. A diagram of these configurations can be seen below. Bipolar electrode placement was used as it was shown to be equally effective, and because of its ease of application.

A 2-group crossover design was used, involving 10 continent women randomly assigned to 2 study groups, each receiving both treatments in random order. The force of PFM contraction was measured using a vaginal pressure probe attached to a manometer, seen in the figure below. No difference in pressure was found between the two methods of electrode placement; however, the Dumoulin method required less current amplitude to achieve the same pressure and was better tolerated by the subjects. The study concluded that greater pressures could be more comfortably reached using the Dumoulin method.

The advantage of this trial was that it was randomized. The disadvantages were that it involved only a small and specific sample population of women who did not suffer from incontinence and it tested the bipolar electrode pattern rather than the conventional quadripolar pattern. It’s important to note that this study was to develop treatment guidelines for the following study on postpartum women.

2. Postpartum Women = Dumoulin et al. (Part 2) ^[2]

This trial examined 8 postpartum women who’d suffered from USI for over 3 months after delivery. Treatment included pelvic floor reeducation for 9 half hour sessions combining IFT and pelvic-floor muscle (PFM) exercises. 5 subjects became continent and conditions improved for the other 3. After the intervention the PFM strength was greater and the volume of urine loss and frequency of incontinence were lower after the intervention. A 1-year follow-up survey found these results to remain consistent.

The advantage of this trial was that it involved a significant intervention time. The disadvantages were that it used only a small and specific sample population of women and it mixed 2 modes of treatment rather than determining the most effective.

3. Elderly Overactive Bladder Incontinence = Oh-oka ^[4]

The focus of this study was the ability of IFT to inhibit detruser muscle contraction. This muscle is responsible for activating the urge to empty one’s bladder. Therefore an overactivity of this muscle results in a form of incontinence known as overactive bladder (OAB).

80 elderly patients between the ages of 69 to 78 years with OAB incontinence were given 3 months of IFT. The frequency of incontinence and volume of urine loss were reduced and improvements were seen in the quality of life questionnaires related to a greater average time spent outdoors. These effects were seen after an average of 8 sessions and the improvements were found to last 3 months post-intervention.

The advantages of this trial were that it examined a large sample population over a relatively long time and conducted a follow-up study to determine the longevity of the treatment effects. The disadvantage was that it focused on overactive bladder incontinence that is relevant to, but not exactly USI.

4. Comparing Different USI Severity = Turkan et al. ^[5]

This study examined the effectiveness of IFT with Kegel exercises in treating patients with different intensities of USI. 48 patients were assigned to 3 study groups according to the severity of their USI and were given 15 sessions over 5 weeks. The results showed that the number of pads used per day, voiding frequency and leakage decreased while the PFM strength and QoL increased. 88% of the mild USI group and 18% of the moderate group were cured of their condition while none of the severe group showed a cured effect, indicating that IFT treatment is better suited to mild and moderate than severe USI.

The advantage of this trial was that it used a relatively large sample population. The disadvantage was that it combined IFT with Kegel exercises rather than focusing primarily on IFT, or comparing the two treatments.

References

1.     Dumoulin, C., Seaborne, D. E., Quirion-DeGirardi, C. & Sullivan S. J. (1995). Pelvic-floor rehabilitation, part 1: comparison of two surface electrode placements during stimulation of the pelvic-floor musculature in women who are continent using bipolar interferential currents. Journal of the American Physical Therapy Association, 75(12), 35-42.

2.     Dumoulin, C., Seaborne, D. E., Quirion-DeGirardi, C. & Sullivan S. J. (1995). Pelvic-floor rehabilitation, part 2: pelvic-floor reeducation with interferential currents and exercise in the treament of genuine stress incontinence in postpartum women – a cohort study. Journal of the American Physical Therapy Association, 75(12), 44-49.

3.     Green, R. J. & Laycock, J. (1990). Objective methods for evaluation of interferential therapy in the treatment of incontinence. IEEE Transactions on Biomedical Engineering, 37(6), 615-623.

4.     Oh-oka, H. (2008). Efficacy of interferential low frequency therapy for elderly wet overactive bladder patients. Department of Urology Kobe Medical Center Japan, 24(2), 178-181.

5.     Turkan, A., Inci, Y. & Demirturk, F. (2005). The short-term effects of physical therapy in different intensities of urodynamic stress incontinence. Gynecologic and Obstetric Investigation, 59(1), 43-48.

Part 2: Interferential Therapy

In the treatment of Urinary Stress Incontinence (USI), Electrical Stimulation aims to improve the strength of the Pelvic Floor Muscles (PFM) to increase urethral closure pressure. This is done by stimulation of the pudendal nerves to restore reflex activation, help maintain a coordinated contraction and increase conscious awareness of the PFM ^[2][3]. Studies have shown that Interferential Therapy (IFT) can restore parts of the nervous system necessary for this improved muscle control ^[5]. IFT conventionally uses a four-pole method, where 2 pairs of electrodes are placed externally to direct current flow to the level of the PFM ^[4]. An advantage of IFT is its external application allowing for ease of application and patient comfort. Either suction cups or carbon silicon electrodes can be used depending on availability and preference. This form of electrotherapy has been found to produce positive results in the management of USI and is well tolerated by patients ^[2].

In comparison to TENS, IFT is more effective in stimulating deeper bodily structures as it utilizes a medium frequency of around 2 to 4 kHz ^[4]. Because the skin acts as a high pass filter, the IFT current is able to penetrate deep enough to reach the PFM, where a lower frequency would fall short. Traditional low-frequency TENS is predominantly used for superficial structures more directly; therefore, in order to stimulate the PFM intravaginal electrodes are used ^[4]. The invasiveness of this method is not well tolerated, resulting in a lack of compliance. An example of an intravaginal electrode is shown in the figure below ^[6].

This Interference Current has the therapeutic properties and sensations of low frequency stimulation. IFT traditionally uses 4 electrodes in an orthogonal pattern, but 2 electrodes in a bipolar pattern can also be used. In a bipolar system the current is ‘pre-modulated’ within the machine, instead of being generated in the body. The figure below is a diagrammatic representation of the orthogonal pattern ^[4].

It must be noted that electrical stimulation is not commonly used as the first approach to management of USI, but rather is used after other methods have failed. It is predominantly used for those who are initially unable to contract their PFM, but once active control is possible regular PFM exercises may be more effective ^[1].

References

1.     Berghmans, L. C. M., Hendriks, H. J. M., Bo, K., Hay-Smith, E. J., De Bies, R. A. & Van Waalwijk, E. S. C. (1998). Conservative treatment of stress urinary incontinence in women: A systemic review of randomized clinical trials. British Journal of Urology, 82, 181-191.

2.     Demirturk, F., Akbayrak, T., Karakaya, I. C., Yuksel, I., Kirdi, N., Demirturk, F., Kaya, S., Ergen, A., Beksac, S. (2008). Interferential current versus biofeedback results in urinary stress incontinence. Swiss Medical Weekly, 138(21-22), 317-321.

3.     Eriksen, B. C. (1990). Electrostimulation of the pelvic floor in female urinary incontinence. Acta Obstetricia et Gynecologica Scandinavica, 69, 359-360.

4.     Green, R. J. & Laycock, J. (1990). Objective methods for evaluation of interferential therapy in the treatment of incontinence. IEEE Transactions on Biomedical Engineering, 37(6), 615-623.

5.     Veale, J. L., Mark, R. F. & Rees, S. (1973). Differential sensitivity of motor and sensory fibres in human ulnar nerve. Journal of Neurology, Neurosurgery, and Psychiatry, 36, 75-86.

6.     Intravaginal Electrode [Image] (n.d.) Retrieved from http://www.healthcare4all.co.uk/images/tenscare-anal-probe.jpg