Interferential current versus biofeedback results in urinary stress incontinence

a Gaziosmanpaşa University, School of Physical Education and Sports b Hacettepe University, Faculty of Health Science , Department of Physical Therapy and Rehabilitation,Women’s Health Unit, Samanpazarı, Ankara, Turkey c Mugla University, Muğla School of Health Sciences, Department of Physiotherapy and Rehabilitation, Muğla, Turkey d Gaziosmanpaşa University, Obstetrics and Gynaecology e Hacettepe University, Department of Urology f Hacettepe University, Department of Obstetrics and Gynaecology

Background: Urinary stress incontinence is a common, disruptive and potentially disabling condition in which the subject complains of involuntary leakage on effort or exertion or on sneezing or coughing.
Aim: This study was performed in order to compare the effects of interferential current and biofeedback applications on incontinence severity in patients with urinary stress incontinence.
In addition, pelvic muscle strength and quality of life as important parameters in these subjects were investigated.
Methods: In this prospective, randomised, controlled study, forty women with moderate intensity of urinary stress incontinence as determined by one-hour pad test were included.Pelvic muscle strength was evaluated by a biofeedback device and quality of life was assessed by a 28itemed questionnaire.All of the parameters were evaluated before and after the treatments.Tw enty cases underwent interferential current therapy, while pelvic floor exercises via biofeedback were applied in the remaining cases.The treatments lasted 5 minutes per session, three times a week for a total of 5 sessions.
Conclusions: Physical therapy modalities used in this trial are applied easily and non invasive.Also, when the finding that no adverse effects were observed during the study period is taken into consideration, it can be concluded that both methods can be used effectively in patients with urinary stress incontinence.

Key words: urinary stress incontinence; interferential current; biofeedback; pelvic floor exercises; quality of life
Urinary stress incontinence (USI) is defined as the complaint of involuntary leakage on effort or exertion, or on sneezing or coughing [].
Pelvic floor muscle weakness plays an important role in USI aetiology [2, ].Pelvic floor muscles work to support the bladder neck in the intraabdominal cavity and maintain urinary continence.Weakness of these muscles leads the bladder to shift to the extra-abdominal cavity and thus a change in the urethra-vesicle angle occurs.As a result, the result of intra-abdominal pressure

Introduction
No financial support declared.

Abstract
strengthening weak pelvic floor muscles in order to increase the low urethral closure pressure, thus eliminating incontinence and improving quality of life.Therefore, pelvic floor re-education methods including Kegel exercises, biofeedback (BF), electrical stimulation, vaginal cones and bladder training can be used in the treatment of this problem [-5, 8].
BF offers the patient the chance to manipulate electro-physical responses of his/her pelvic floor muscles according to visual and auditory signals.Most women are not aware of how their pelvic floor muscles work.BF is used especially to teach muscle functions and to check if the exercises are performed correctly [, 9].
Reports of incontinence therapy by electrical stimulation are to be found in the literature since 96 [4,[0][1][2].Electrical stimulation aims to improve the urethral closure pressure by restoration of reflex activation of the pelvic floor muscles, maintaining synchronised contraction of these muscles in addition to the strengthening effect [4].
Interferential current (IC) as one of the medium frequency currents, is commonly used in the treatment of USI.IC can be applied with two or four electrodes and effective low frequency occurs in that area where the medium frequencies intersect within the pelvis to stimulate the pelvic floor.Ease of usage and external application without giving harm to the superficial tissues are the main advantages of this method.The current produces positive responses in the body and the intensity is well tolerated by the patients [, 4, , 4].
In the literature, although a great deal of knowledge exists about the use and effectiveness of physical therapy, there are only a limited number of studies about the comparison of different physical therapy methods in USI.The aim of this study is to compare the results of IC and BF and to investigate if these two modalities have similar effects on incontinence severity, pelvic muscle strength and quality of life in patients with USI.

Materials and methods
This prospective randomised and controlled study, which aimed to compare the results of different physiotherapy techniques in patients with USI, was approved by the Hacettepe University, Ethics Committee of the Faculty of Medicine, and supported by the Scientific Research Centre of the same university (project number: 998 02 40 002).
The cases were diagnosed as urinary stress incontinence by an urologist and a gynaecologist and referred to Hacettepe University, School of Physical Therapy and Rehabilitation, Women's Health Unit, between the years 998-2005.Diagnosis was made according to the detailed history, clinical and physical examinations and urodynamic tests (MMS UD 2000 B.V. Netherlands).Among 6 cases referred as having USI, those with urinary tract infections, detrusor over activity, cognitive problems and neoplasm were excluded, and those with moderate intensity of incontinence as determined by a one-hour pad test were randomly assigned into IC and BF groups, according to the application order.The patient flow diagram is presented in figure .
Age, height, weight and body mass index values were recorded as physical characteristics.Number of pregnancies, parity, abortions, dilatation & curettage (D&C), type of delivery and presence of episiotomy and/or perineal tears were recorded as obstetrical history.Duration of the incontinence problem and menstrual status of the subjects were determined.In addition, duration of menopause for those subjects in the postmenopausal period was recorded.
Smoking habit and alcohol consumption, presence of constipation, chronic coughing, allergy, heart disease, blood pressure problems and diuretic drug usage were recorded because of their possible effects on urinary incontinence.
A one-hour pad test was performed to determine the incontinence intensity [].A sensitive balance (Sartorius, BP 0 S) was used to measure the weight of the pad before and after the test and the difference was recorded as the amount of urine leakage.
Pelvic floor muscle strength was measured with BF device (Myomed 92 Enraf Nonius) in lithotomy position, using a vaginal probe.For each case, measurements were performed three times and the mean value was noted as the pelvic floor muscle strength.Before the test, subjects were asked not to hold their breath, or contract their abdominal, gluteal or thigh muscles during the evaluation, in order to obtain an accurate value of pelvic floor muscle strength.The same physiotherapist performed pre-treatment and post-treatment measurements, by controlling the interference of the above mentioned muscles.
A 28 itemed questionnaire graded from 0 to for each item (0 = best score, 84 = worst score) was completed by the subjects in order to determine the effects of the incontinence problem on the quality of life [5].
In 20 patients IC with a frequency of 0-00 Hz was applied for a duration of 5 minutes, three times a week for a total of 5 sessions.Tw o vacuum electrodes were placed in the suprapubic region, whilst another two were positioned near to the medial side of the ischial tuberosity, crosswise.
The second group included 20 subjects, who per-formed Kegel exercises using a BF device during 5 minutes, three times a week, for a total of 5 sessions.The treatment protocol was individually designed and all of the patients were instructed in the use of a BF device to obtain isolated pelvic floor muscle contraction.Before starting the treatment, duration of maintenance of maximum contraction of the pelvic floor muscles was determined for each patient.This duration was then taken as the working period in the initial treatment sessions, and increased as the capability to maintain the maximal contraction improved.A ten second resting period was given between the working periods.All of the cases were re-evaluated after the treatment program had been carried out on every other day for five weeks.Patients were also observed for possible adverse effects of the methods such as allergic skin reactions, erythema, inflammation and pain.At discharge, cases in both groups were advised to continue with a home program including Kegel exercises in order to maintain the effects of the treatments.

Statistics
Statistical analysis was accomplished on a personal computer by using statistical package for social sciences version 2.0 (SPSS 2.0, demo, SPSS Inc. Chicago, Illinois).Quantitative and qualitative data were presented as convention mean (standard deviation) and n (%), respectively.Intra-group differences of the pad test, pelvic floor muscle strength values and QoLQ scores were analysed by t-test for paired samples.Pre and post treatment differences of means in pad test, pelvic floor muscle strength and quality of life questionnaire values between groups were analysed by t-test for independent samples.95% confidence intervals (95% CI) were used for statistical significance.

Results
The age of the cases was 50.4 (SD = 6.9) years.Physical properties of the subjects in each group are presented in table .The mean duration of incontinence complaint was 6.5 (SD = 6.2) years in IC Group and 5.8 (SD = .)years in BF Group.
Tw elve cases (60%) in BF group and six cases (0%) in IC group were in the postmenopausal period.The mean duration of menopause was 4.8 (SD = 5) years in IC Group and .6 (SD = 5) years in BF Group.
There were no apparent differences between the groups for pregnancies, parity, number of abortions and Dilatation and Curettages (table ).
All but one patient in each group indicated that they had delivered vaginally.Mean number of vaginal labour was (SD = 2) (minimum = 0, maximum = 9) in IC group and (SD = 2) (minimum = 0, maximum = 8) in BF group.One case in IC group and two in the other group had experience of caesarean section.
Eight (40%) cases in IC group and seven (5%) in BF group indicated that they had experienced a perineal tear during labour.Episiotomy was recorded in 2 (60%) cases in IC group and in 0 (50%) cases in the other group.
Factors that may have a possible effect on urinary incontinence such as smoking, chronic coughing, allergic conditions, heart disease, problems with blood pressure, constipation or diuretic drug use are presented in table .

Ta ble 1
Physical characteristics and possible risk factors related to urinary incontinence of the subjects.

Interferential current versus biofeedback results in urinary stress incontinence
Pre and post treatment mean (95% Ci) values of the groups.Change of the values over time in each group.
No adverse effects were observed during treatments.

Discussion
The findings of this study reveal that both IC and BF procedures are of benefit in patients with USI, in regard to improvement in intensity of incontinence, pelvic muscle strength and quality of life.In addition, the degree of improvement experienced using these methods seems to be similar.
Pages et al, compared the effects of pelvic floor exercises and BF in 40 women with USI and found that voiding frequency and the subjective complaints of the cases improved in both groups after four weeks of treatment followed by two weeks with a home program.They indicated that the improvement in voiding frequency was more evident in cases that performed pelvic floor exercises whereas the increase in the pelvic floor muscle strength and reduction of subjective complaints were more evident in BF group [9].
Berghmans et al. investigated the effects of pelvic floor exercises with and without BF application in 44 patients of USI.They have pointed out that the combined approach was more effective than performing pelvic floor exercise alone [22].
In this study, BF was found effective in improving the pelvic floor muscle strength, pad test amount and quality of life questionnaire results.
There are a limited number of studies on the use of IC in USI treatment.Dumoulin et al. investigated the effects of combined IC and exercise on pelvic floor muscle strength and incontinence intensity in eight cases with a postpartum USI prob-lem.They found that all of the parameters improved after three weeks of treatment [2].
Another example of the literature on IC in patients with USI is the study of Tu rkan et al.They presented the results of a physical therapy program consisting of the use of IC and Kegel exercises in patients with different intensities of urodynamic incontinence, but not in comparison with other treatment modalities.They indicated that the program was more effective in cases with mild and moderate incontinence intensity rather than in those with severe incontinence [4].
Parallel to the results of the related literature, BF and IC have been found effective in improving pelvic floor muscle strength, incontinence intensity and QOL of cases in this study.These methods can be used in clinical practice as they are non invasive, easily applied and well tolerated.Interferential current may be preferred when biofeedback application is not appropriate, as in some geriatric patients (in whom cooperation is reduced due to visual or auditory incapacity), in children or in patients who are not willing to use intravaginal/rectal applications.Although statistical analyses revealed that IC and BF seemed to cause similar amount of improvement in the measured variables, results of studies including a greater number of subjects are needed to ascertain any clinically useful differences between the two methods.
As the follow-up period of all cases is not completed, it is planned to present the long term results of these treatments in a further study.Subjects who successfully perform a home program will be compared with those who fail to sustain the exercise program.
The points that can be investigated in further studies include the results of IC and BF in different intensities of USI, comparison with the results with other physiotherapeutic approaches and the effects of different frequencies of IC in USI patients.