EVALUATION OF A MOBILE ELECTRODE FOR ELECTRICAL

STIMULATION OF THE PERINEAL MUSCLE

Preventive or Therapeutic Treatment

Fabiana S. B. Perez

School of Medicine, University of Brasilia, Brasilia, DF, Brazil

Adson F. da Rocha, Joao Luiz A. Carvalho, Patricia M. C. Paula

Department of Electrical Engineering, University of Brasilia, Brasilia, DF, Brazil

Cleyciany B. Cruz

Faculty Padrão, Goiania, GO, Brazil

Keywords: Perineal dysfunction, Electrical stimulation, Mobile electrode, Electrotherapy and physiotherapy.

Abstract: This work evaluates the effectiveness of a new type of electrode for functional electrical stimulation of the

perineal muscle in women and in men. The new electrode is shaped like a pen, with an active stimulation

electrode located on its tip. The goals of the study are to (i) demonstrate that stimulation using the new

device results in increased muscle strength; and (ii) compare the performance of the new device with that of

a traditional (fixed) electrode. Eight patients were evaluated, following a blind study protocol. The

preliminary results suggest that stimulation with the new electrode achieves better results than stimulation

with traditional electrodes, as higher increases in strength were observed in the group that used the mobile

electrode for preventive treatment and as an option of therapeutic treatment for female and for male perineal

dysfunction, in particular on erectile dysfunction in men with spinal cord injury.

1 INTRODUCTION

The perineum is a diamond-shaped muscle group

located between the pubic symphysis, the ischial

tuberosities, and the coccyx. It is separated from the

pelvic cavity by a set of structures forming a pelvic

diaphragm, which is composed by the

pubococcygeus, iliococcygeus, and coccygeus

muscles (Galhardo et al., 2007; Godec et al., 1975

These muscles occlude the pelvis, and provide

support for the pelvic viscera when there is an

increase in the intra-abdominal pressure due to

physiological events such as coughing, bowel

movements, laughing, carrying weight, pregnancy,

birth delivery and sexual intercourse. This happens

through the effective contraction and relaxation of

the muscles of the pelvic floor. Perineal

dysfunctions and psychosocial problems may occur

if this coordinated action does not occur properly.

One solution to these dysfunctions is to

strengthen the perineal muscles. This can be

achieved through physical therapy techniques known

as Arnold Kegel exercises (Moreno, 2004;

Berghmans, 2006). However, some patients are

unable to perform such exercises. In such cases,

electrical stimulation may be used. Electrical

stimulation of the perineal muscles has shown

satisfactory therapeutic results in many etiology

studies (Castro et al., 1998). Electrical stimulation

has been widely used in the past years (Castro, 1998;

Nielsen et al., 1992; Okada et al., 1992; Modotte et

al., 1999) and has presented good results, especially

using intracavitary electrodes. The performance of

this technique depends on the choice of electrode,

type of wave, amplitude, cycle, pulse, and frequency

(Marques, 2008).

The treatment of perineal pathologies typically

uses intracavitary electrodes. However, studies show

256

B. Perez F., da Rocha A., A. Carvalho J., C. Paula P. and Cruz C..

EVALUATION OF A MOBILE ELECTRODE FOR ELECTRICAL STIMULATION OF THE PERINEAL MUSCLE - Preventive or Therapeutic Treatment.

DOI: 10.5220/0003173402560259

In Proceedings of the International Conference on Biomedical Electronics and Devices (BIODEVICES-2011), pages 256-259

ISBN: 978-989-8425-37-9

 2011 SCITEPRESS (Science and Technology Publications, Lda.)

adverse effects due to intra-cavity electrical

stimulation with this type of electrode, such as: pain,

unpleasant sensations, fecal incontinence, vaginal

irritation and infection (Sand et al., 1995; Yamanish,

2000). Moreover, patients with spinal cord fall into a

group of contraindication for electrical stimulation

of the perineal intracavitary electrodes, Figure 1A,

due to a sensory - motor change.

Due to these drawbacks, this work investigates

an innovative non-intracavitary type of electrode:

the mobile electrode, which uses a different mode of

application.

This study compares a treatment that uses a fixed

electrode to stimulate the muscles of the perineum

with a treatment that uses a mobile pen-shaped

electrode. The choice of electrodes is based on the

study of Modotti et al. (1999). The mobile electrode

has the size of a pen-tip, and can more adequately

stimulate the motor point and the fibers of the small

muscles in comparison with the fixed electrode,

which stimulates only one or two muscles, and

whose size makes its adaptation to the perineal

region more difficult.

We evaluate the effectiveness of the fixed

electrode and the pen-electrode in the recruitment of

muscle fibers of the perineum and the time required

to achieve a given level of strength. Preliminary

results are presented. Improved muscle stimulation

may help in curing and preventing diseases, by

strengthening the muscle.

2 METHODS

The study was conducted at Cerei Clinical Center

(Goiânia, GO, Brazil). The protocol was approved

by the ethics and research committee of the Faculty

of Medicine of the University of Brasília. Eight

volunteers of 37.5 ± 7.65 (mean ± s.d.) years of age

were chosen according to the evaluation of a

questionnaire for inclusion or exclusion. The

patients selected should be linked to the institution,

between 25 and 50 years old, with no surgical

correction of perineal pelvic floor disorders,

sedentary, non-users of medical drugs other than

contraception, sexually active, non-obese and have

agreed to participate voluntarily in the research. The

volunteers were blindly/randomly allocated into two

groups, according to their arrival. After signing the

consent, the volunteers were subjected to

gynecological and strength evaluation using a

Neurodyn Evolution perineal biofeedback device

(Ibramed Ltda., Amparo, SP, Brazil) with a vaginal

pressure probe (Ibramed Ltda., Amparo, SP,

Brazil). The probe was coated with a condom, and

lubricated externally with carbogel. The device

measures the maximum and minimum cavity

pressure achieved by voluntary contraction of the

perineum. After evaluation, the patient was

subjected to the protocol of group A or B according

to the assigned group.

The experimental protocol consists of two

procedures, each applied to one of the two groups of

subjects. In group A, the patients were subjected to

electrical stimulation of the pelvic floor muscles by

pen-electrode stimulation of five points around the

vaginal opening in an arc that starts on one side of

the groin and ends on the other side, passing through

the centre of the pubic arch. This stimulates five

motor points in different muscles, by moving the

mobile pen-electrode during the thirty minutes of

therapy. The five points of the perineal region are:

the pubic region, central tendon, bilateral inguinal

region, near the labium majus, and in the direction of

the vaginal opening. The stimulator generates

seventy impulses at each session toward a total of 14

pulses per point muscle during each session. The

pen-electrode was fixed during six minutes at each

point in each session.

In the use of mobile electrode for

electrotherapeutic application in male patients with

erectile dysfunction and partial Raqui-Medullar

Trauma (RMT) is obtained satisfactory results, but

with electrode application in the body of the penis,

scrotum and central tendon.

Figure 1A shows the use of intracavitary

electrode which in man should be anal with the

patient positioned in lateral recumbence. Figure 1B

shows the fixed external electrode positioned

bilaterally in the groin which does not allow the

visualization of local skin response. Figure 1C

shows the mobile electrode in the penis body

showing the swelling of the penis.

Figure 1: A) Intracavitary electrode; B) Fixed electrode;

C) Mobile electrode.

The electrode intensity instead of going on the

threshold of the patient pain, it goes to the moment

when the therapist visualizes the scrotal contraction

or the swelling of the penis, Figure 1C.

EVALUATION OF A MOBILE ELECTRODE FOR ELECTRICAL STIMULATION OF THE PERINEAL MUSCLE -

Preventive or Therapeutic Treatment

257

Group B participants were subjected to electrical

stimulation using fixed electrodes. A group of four

electrodes, arranged in a cross shape, were placed

around the vaginal opening, thus stimulating only

two muscles. The two electrodes from cable 1 were

arranged on the central tendon and the pubis, thus

stimulating this region. The two electrodes from

cable 2 bilaterally stimulate the groin, closing the

vaginal opening. Seventy impulses were used to

simultaneously stimulate these four points during

thirty minutes of therapy.

A Neurodyn Ruby stimulator (Ibramed Ltda.,

Amparo, SP, Brazil) was configured as follows for

both groups: low frequency synchronous FES with

the following envelope: frequency = 20 kHz; period

= 50 µs; rise = 7 s; on = 10 s; decay = 10 s; off = 5 s;

time = 30 minutes. The current intensity was

adjusted according to each patient’s sensibility,

provided that the electrical stimulation reaches the

motor threshold of the muscle without triggering a

painful stimulus. A vaginal probe was introduced in

the vagina of the patient during electrotherapy, using

a Neurodyn Evolution perineal biofeedback device

(Ibramed Ltda., Amparo, SP, Brazil) to check the

pressure before and after vaginal electrotherapy in

order to observe whether there is increase in strength

or muscle fatigue caused by the electrical

stimulation. The FES frequency was chosen due to

its extensive use in the literature (Godec et al., 1975;

Nielsen et al., 1992; Okada et al., 1999, Yamanish et

al. 2000). The protocol was repeated in 12 sessions,

performed twice a week, at a total time of 30

minutes per session.

A comparative analysis of muscle fatigue of the

subjects of group A compared to group B was

performed. For each subject, the intra-session

increase in muscle strength was calculated as the

difference between end pressure (after electrical

stimulation) and initial pressure (before electrical

stimulation). The inter-session increase in muscle

strength was evaluated by linear regression of the

measured pressures from each subject.

3 RESULTS AND DISCUSSIONS

This work presents current results from an ongoing

study. Therefore, only data from the first 7

experimental sessions (out of 12) are presented.

However, the study is still in progress and complete

results will be published at the end of the

experiments.

Local muscle fatigue is a decrease in muscle

response to a repeated stimulus, i.e. a normal

physiological response of muscle is characterized by

a decrease in amplitude of motor unit potential

(Kisner, 2009). Table I presents and the angular

coefficient of the linear regression on the 7

measurements (sessions) from each subject. Positive

angular coefficients indicate a tendency of

increasing pressure with each additional session, i.e.,

an increase in muscle strength due to periodic

electrotherapy. Three out of four subjects in group A

presented positive angular coefficients, while only

one out four subjects in group B presented positive

slopes.

Table 1: Initial pressure in each session (in mmHg) and

corresponding linear regression angular coefficients.

Group Session S1 S2 S3 S4 S5 S6 S7

Angular

coefficient

Subject 1

5 113 47 57 132 69 93 −4.6071

Subject 2 64 39 92 77 73 72 84 3.8214

Subject 3 41 49 41 42 45 42 64 3.8214

Subject 4 51 50 62 39 48 51 56 0.1071

Subject 1 38 46 40 40 30 35 31 −1.8929

Subject 2 1 40 52 2 14 72 87 10.1429

Subject 3 79 76 131 106 101 105 2 −7.2500

Subject 4 56 62 63 49 46 62 55 −0.7143

The measured pressure at the beginning of each

session for each subject of group A is showed in

Figure 2 and for group B in Figure 3. These results

suggests a trend of increased strength between

successive sessions for subjects stimulated with the

mobile electrode (group A), and a trend of strength

loss in subjects stimulated with the fixed electrode

(group B). The mobile electrode was expected to

provide higher strength gain, because force

production is directly related to the number of

stimulated motor points [8].

Figure 2: Measured muscle pressure at the beginning of

each session for each subject of group A.

BIODEVICES 2011 - International Conference on Biomedical Electronics and Devices

258

Figure 3: Measured muscle pressure at the beginning of

each session for each subject of group B.

Treatment with intracavitary electrode is not

indicated for patients with altered sensitivity because

it might cause injury which will not be perceived by

the therapist and/or by the patient, on the other hand

with the conventional electrode (fixed) it might

cause injure due to the static positioning on the skin

surface during the therapy without the visualization

of the skin surface of the patient with altered

sensitivity, Figure 1B.

With the new mobile electrode (pen), the electrical

load is greater at the tip of the conductor with an

intense electric field which can trigger faster the

action potential in the injured muscle, and because

of being mobile and external even with changing

sensory of the patient, the therapist is able to

visualize the muscle contraction even though the

patient does not notice, and monitor the dermal

reaction of it to prevent injury, Figure 1B.

4 CONCLUSIONS

Preliminary results suggest that the pen-electrode is

more effective than the fixed electrode in providing

gain of perineum muscle strength. The comparison

was performed using similar protocols with respect

to duration and current administration, differing only

for the fact that, with the pen-electrode, each point

received 14 stimulated impulses during the thirty-

minute pulse therapy, while seventy impulses were

used for each of the four points during the sessions

with the fixed electrode.

The preliminary results suggest that the pen-

electrode may be a better option for electrotherapy

than the fixed electrode in the prevention and in the

treatment of perineal dysfunction of, highlighting the

possibility of the use in patients with reduced

sensitivity, for example, the spinal cord injured.

The group that received stimulation with fixed

electrodes showed a reduction in strength,

suggesting a slower perineal muscle response due to

muscle fatigue, which occurs during prolonged

simultaneous stimulation of the four fixed points.

The mobile pen-electrode stimulates five points non-

simultaneously. The increased strength resulting

from a minor muscle fatigue can possibly shorten

the therapy duration and reduce the financial costs to

the patient.

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Preventive or Therapeutic Treatment

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