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
Thanks for fixing the image in post#1. there is a little too much redundancy in this post, meaning your peers all know about basic interferential theory. Don't stress and don't change it now. Also the phrase 'interfering with each other' is poorly put here. It sounds dodgy! better to risk plagiarism and describe the 'creation of an interferance pattern' - better still to skip over this as it was given in lectures. Preferably you would expand on the reasoning for IFT over TENS for USI not only with reference to the target muscle's depth (as you have done a little bit) but also to the pertinence (in this delicate anatomical region) of placing electrodes at some distance from the target, instead of directly over it, as one does with, say, NMES. Maybe in a subsequent post you were planning on doing so? cheers CY
ReplyDeleteMuch, much better, thanks CY
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