What Do We Conclude From The Literature?

Evidence of Electrical Stimulation and the Management of Urinary Stress Incontinence.

The evidence of 7 RCT’s using electrical stimulation found inconsistent results, showing no cure or overall improvement of urinary incontinence in women, compared to sham stimulation or PFM training. Two of the studies found that electrical stimulation resulted in continence in about 20% of women (Bo et al., 1999; Smith, 1996). However despite the short term success of electrical stimulation in the above studies, a six month follow-up failed to show any statistically significant benefit from electrical stimulation compared to other physiotherapy management or medications. The remaining RCTs also did not display any significant benefits of electrical simulation when compared with the outcomes of Kegel exercises (Smith, 1996), biofeedback-assisted training (Pages et al., 2001), or placebo trials (Luber & Wolde-Tsadik, 1997: Fujishiro, 2000; Yamanishi et al, 1997; Yamanishi et al., 2000).

Evidence Specific to Interferential Treatment

Turkan et al., 2005, examined the short-term effects of physical therapy throughout the different intensities of urodynamic stress continence. Interferential current therapy and kegel exercises were both undertaken in the intervention, resulting in the conclusion that the combination treatment was more effective in mild and moderate cases rather than those with severe incontinence.

Dumoulin et al, 1995 found an increase in PFM strength and a subsequent decrease in quantity and frequency of incontinence; following the implementation of a combined physical therapy and interferential program, using suction cups.

A comparative study between interferential current and biofeedback found both modalities to be beneficial to those with USI. They noted an improvement in continence, pelvic muscle strength and quality of life. Finding no significant difference between biofeedback and interferential (Demirturk et al., 2008).

CONCLUSION
After looking at all the evidence for interferential therapy, we have come to the conclusion that it is quite a beneficial treatment for the pelvic floor, when combined with other interventions such as kegel exercises. It is considerably less invasive than other Estim techniques, and also does not produce as much skin irritation. When interferential current is used in isolation it seems to produce decent results concerning the restoration of PFM strength. The PFM play a vital role in one’s continence, and further investigation is required to determine whether the improvements gained from interferential therapy are maintained in the long term.


Adios Amigos
Mitch & Christie

REFERENCES:
Bø, K., Talseth, T., Holme, I. (1999). Single blind, randomised controlled trial of pelvic floor exercises, electrical stimulation, vaginal cones, and no treatment in manage- ment of genuine stress incontinence in women. BMJ. 318:487-93.

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, 317-321.

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 treatment of genuine stress incontinence in postpartum women - A Cohort study. Physical Therapy, 75(12): 1075-1081.

Fujishiro, T., Enomoto, H., Ugawa, Y., Takahashi, S., Ueno, S., Kitamura, T. (2000). Magnetic stimulation of the sacral roots for the treatment of stress incontinence: an investigational study and placebo controlled trial. J Urol. 164:1277-9.

Luber, K. M., Wolde-Tsadik, G. (1997). Efficacy of functional electrical stimulation in treating genuine stress incontinence: a randomized clinical trial. Neurourol Uro- dyn. 16:543-51.

Pages, I. H., Jahr, S., Schaufele, M. K., Conradi, E. (2001). Comparative analysis of biofeedback and physical therapy for treatment of urinary stress incontinence in women. Am J Phys Med Rehabil. 80:494-502.

Sand, P. K., Richardson, D. A., Staskin, D. R., Swift, S. E., Appell, R. A., Whitmore, K. E., et al. (1995). Pelvic floor electrical stimulation in the treatment of genuine stress incontinence: a multicenter, placebo-controlled trial. Am J Obstet Gynecol. 173:72-9.

Smith, J. J. 3rd. (1996). Intravaginal stimulation randomized trial. J Urol. 155: 127-30.

Turkan, A., Inci, Y., Fazli, D. (2005). The short- term effects of physical therapy in different intensities of urodynamic stress incontinence. Gynecol Obstet Invest, 59:43-48.

Yamanishi, T., Yasuda, K., Sakakibara, R., Hattori, T., Ito, H., Murakami, S. (1997). Pelvic floor electrical stimulation in the treatment of stress incontinence: an in-vestigational study and a placebo controlled double-blind trial. J Urol. 158: 2127-31.

Yamanishi, T., Yasuda, K., Sakakibara, R., Hattori, T., Suda, S. (2000). Randomized, double-blind study of electrical stimulation for urinary incontinence due to de-trusor overactivity. Urology. 55:353-7.

Electrode Placement

Bi polar electrode placement was shown to produce as equally effective stimulation as quadripolar electrode placement (Dumoulin et al., 1995). This electrode placement is seen to be preferential based on the relative ease of its application, and can be seen in the image below:

(Dumoulin et al., 1995)

The pudenal nerve, the nerve which we target when we use electrical stimulation to contract the pelvic floor is located approximately 7.5-10cm within our pelvic cavity. Therefore the intensity (amplitude) required to produce a contractions of the pelvic floor can cause painful sensations;  understandably resulting in apprehension and discomfort for the user. The user's discomfort is often the limiting factor in obtaining an effective contraction of the PFM. Discomfort can decrease the effectiveness as the intensity required to maximally contract the PFM is often intolerable to the user.

A study by Dumoulin et al., 1995, comparing the placements of 2 surface electrode during stimulation of the PFM in continent women, reported that particular discomfort was experienced by participants, who were using bipolar interferential.  Understandably as the electrodes were placed posteriorly between the ischial tuberosities over the anus and anteriorly over the clitoral region. Maximal discomfort was felt by the women under the anterior electrode due to a high levels of current, focused on such a small sensitive area.

Because of the discomfort felt by the women an alternative electrode placement was suggested to decrease their discomfort. The anterior electrode was re-positioned above the pubic symphysis, which in theory:

·         Increases the current spread to ~140cm (Laycock & Green 1988). 

·         Decrease pain

·         Potentially increase stimulation of motor nerve of the pubococcygeus muscle.

A Vaginal pressure probe (manometer) was used to measure the strength of the PFM contraction with the new electrode positioning and no differences in maximal contraction (amplitude) were observed between the different electrode placements. 

REFERENCES:

Dumoulin, C., Seaborne, D., Quirion- DeGirardi, C.  & Sullivan, S. (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. Physical Therapy. 75 (12) 1067-1074.

Laycock, J. & Green, R. (1988). Interferential therapy in the treatment of incontinence. Physiotherapy. 74: 161-168.

Interferential vs TENS

As i dabbled on in earlier posts, neuromuscular stimulation (NMES) has been shown to be effective in the treatment of USI. (Dumoulin et al. 1995) Activation of the PFM and a subsequent increase in urethral closing pressure has been shown to effectively stimulate the pudendal nerve at frequencies between 20-50 HZ (Dumoulin et al. 1995).
In addition to this NMES can increase conscious awareness of the action of our PFM, ultimately increasing our ability to perform a voluntary muscle contraction.  Treating the primary weakness of in most cases of USI.

Different methods compared

Several electrical methods have been used to stimulate the PFM; these include low frequency faradic currents and medium frequency interferential currents.

The use of interferential, medium frequency currents are used in order to effectively stimulate the deep structures without the need of more invasive techniques

This has commonly been a problem with TENS, as it predominately stimulates the more superficial structures. In technical terms, has been found that the resistance of tissues increases inversely to the current frequency (Fall & Lindstrom 1991). Therefore higher frequencies are required to penetrate deeper structures, which can be very uncomfortable.

Traditionally intravaginal electrodes have been used with tens so direct stimulation of the PFM could occur.  This method is highly invasive and is not well tolerated by the user, with an example machine shown below:

http://www.medwest.com.au/index.php?cPath=2_14&&page=5

Bi and quadripolar interferential currents decrease the surface reactance, decreasing the overall tissue resistance and enabling the stimulation of deep structures such as the pelvic floor (Dumoulin et al. 1995, Yamanishi & Yasuda, 1998).

REFERENCES:

Baessler, K., Schussler, B., Burgio, K., Moore, K., Norton, P. & Stanton, S. (2008). Pelvic Floor Re-education. Springer. London.

Fall, M. & Lindstrom, S. (1991) Electrical stimulation. Urologist Clinical North America. 18: 393-407.

Yamanishi, T. & Yasuda, K. (1998). Electrical stimulation of stress incontinence. International Urogynecology Journal and Pelvic Floor Dysfunction. 9: 281-290.

Focusing on Interferential

As mentioned in my earlier posts the primary aim of treatment in USI is to increase the strength of the weak PFM. An increase in PFM strength will help increase urethral closure pressure, resulting in decreased urinary incontinence.  A vital aim with all USI modalities.


Electrical stimulation therapy has been reported in literature for the use of USI treatment since the 1960’s and 70’s (Alexander & Rowan, 1970).

As I also mentioned the previous post, the two main types of electrical stimulation presently used are biofeedback and interferential current therapy.  This post aims to focus on interferential current and its specific applications towards USI treatment.

Interferential current therapy is aimed at restoring normal physiological reflexes in the abnormal nerves and muscles. Interferential current is specifically aimed at increasing urethral closure pressure by restoring the reflex activation of PFM, whilst encouraging the synchronised contraction of all the PFM and increasing their individual strength (Turkan et al. 2005). This all seems very confusing and complex but put in simple terms, interferential current will contract our pelvic floor in in the right sequence when we cannot subconsciously or even consciously do so.

As well as increasing the strength and coordination of the PFM, (Bo et al. 2007) interferential therapy can act by inhibiting detrusor muscle contraction (Yamanishi & Yasuda, 1998). The detrusor muscle instigates the urge to empty one’s bladder, and overactivity of this muscle is common in people with overactive bladder dysfunction.


Two categories of electrical stimulation explained 

Estim can be divided into 2 major categories; neurostimulation and neuromodulation.

Neural stimulation
Neural stimulation works to stimulate the efferent fibres of the pudendal nerve at S2 and S3, which innervate the PFM.  A direct response at the effector organ the PFM, results in increased neural activation, causing the PFM to contract (Scheepens, 2003). In basic terms by stimulating the nerves that send the message from the brain telling the pelvic floor to contract, we can activate and retrain the PFM to contract effectively. 

Neuromodulation

http://www.sghurol.demon.co.uk/urod/neuro.htm

Our bodies have a reflex that stops us from constantly feeling like we need to go to the toilet, when we have any fluid in out bladder. This reflex stops the detrusor muscle (the muscle that contracts over the bladder, giving us the urge to pass urine) from activating therefore removing the constant urge to go to the toilet. Neuromodulation achieves the above process by reorganisation of the nerves pathways, subsequently re-stimulating  the detrusor inhibition reflex. 

Specific parameters for interferential current

Interferential current uses 2 medium frequency currents, applied via 2 or 4 electrodes. The intersection of the two medium frequency currents, generates an interference current which has the characteristics of low frequency stimulation on the PFM (Demirturk et al. 2008).

For example:

A net current of 35 Hz will be produced when two continuous currents of 4000 to 4035 intersect. The picture below gives a  clear diagrammatical representation of the main concept of interferential.

http://www.mstrust.org.uk/professionals/information/wayahead/articles/10042006_06.jsp

One if the main benefits of interferential is that it can be applied externally with no harm to soft tissue. Both carbon silicon or suction cups electrodes can be used in interferential stimulation of the pelvic floor, which can add to ease of application.

The general settings used to stimulate the PFM using interferential are as follows:

·               Multiphasic wave

·               Phase duration- 125ms

·               Pulse rate- 1-200 pulses/sec

·               Total current- 80-90mA
                      Frequency- approx 4000 Hz (interference current 20- 50 Hz) 

Contraindications for electrical stimulation specific to the pelvic floor include:

·              Poor patient cognition

·              Pregnancy

·              Puerperium (First 24 hours after birth)

·              Atrophic vaginitis

·              Reoccurring vaginal infections

·              Recent hemorrhage

·              Malignancies

·              Adverse skin reactions under surface electrodes

General contraindications for electrical stimulation include:

·              Undiagnosed pain (unless recommended by a medical practitioner)

·              Pacemakers

·              Heart disease (unless recommended by a medical practitioner)

·              Increased cellular metabolism

·              Epilepsy (unless recommended by a medical practitioner)

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REFERENCES:

Alexander, S. & Rowan, D. (1970). Electrical control of urinary incontinence: a clinical appraisal. British Journal of Surgery. 57:766- 768.

Baessler, K., Schussler, B., Burgio, K., Moore, K., Norton, P. & Stanton, S. (2008). Pelvic Floor Re-education. Springer. London.

Bo, K., Berghams, B., Van Kampen, M. & Morkred, S. (2007). Evidence based physical therapy for pelvic floor: bridging science and clinical practise. Elsevier Limited. Philadelphia.

Demirturk, F., Turkan, A., Karakaya, I. C., Yuksel., Kirdi, N., Demirturk, F. et al. (2008). Interferential current versus biofeedback results in urinary stress incontinence. Swiss Medical Weekly. 138(21-22): 317-321.

Scheepens, W. (2003). Progress in sacral neuromodulation of lower urinary tract. Thesis. University of Maastricht. The Netherland.

Turkan, A., Inci, Y. & Fazli, D. (2005). The short-term effects of physical therapy in different intensities of urodynamic stress incontinence. Gynecol Obstet Invest. 59: 43-48.

Yamanishi, T. & Yasuda, K. (1998). Electrical stimulation of stress incontinence. International Urogynecology Journal and Pelvic Floor Dysfunction. 9: 281-290.