GB1599466A - Testing device for determination of the optimal position of electrodes on an electrical stimulator - Google Patents

Description

(54) A TESTING DEVICE FOR DETERMINATION OF THE OP fIMAL POSITION OF ELECTRODES ON AN ELECTRICAL SIMULATOR (71) We, SVENSKA UTVECKLING- SAKTIEBOLAGET, a Swedish Joint Stock Company of Fack, 103 40 Stockholm 40, Sweden, do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a testing device for determining the optimal position of electrodes of an electrical stimulator, the device comprising electrodes on an electrode carrier intended to be placed in the vagina or anus, said electrodes being arranged to affect the urethral, bladder and/or rectal function.

Urinary incontinence is a big problem for the individual as well as for the medical attendants. Urinary incontinence is very common and also requires a considerable amount of time for the nursing, like changing clothes and bedding.

Urinary incontinence means involuntary leakage of urine. In principle, urinary incontinence is caused by lowered resistance to flow in the urethra or uncontrolled bladder activity. In some cases, a combination of these two factors exists. Stress incontinence and urge incontinence are typical forms of incontinence due to urethral and bladder factors respectively.

Stress incontinence, that is, leakage of urine when the abdomen pressure is rapidly increased as when coughing, sneezing and lifting, is caused by a weakening of the periurethral tissues. The most widely used treatment is surgery. The surgical results are quite satisfactory; 90% of the patients are cured. In some cases surgery is evidently not so successful, and in other cases, surgery is definitely contraindicated. In still other cases, the patients do not wish to undergo an operation. These cases mainly belong to the large group of patients with less severe symptoms.

Urge incontinence is caused by a hyperactive bladder with different etiologies. The treatment is pharmacological. In many cases the results are not favourable. In mixed types of urge and stress incontinence, a surgical procedure involving the stress component may aggravate the urgency element.

For some years, electrical stimulation has been used as an alternative to treat incontinence. Implanted or external (anal or vaginal) electrodes have been used. With electrical stimulation, it is possible to control different types of incontinence in 30 to 80 percent of the cases. The appliances in use operate with very different electrical parameters. When implanted electrodes were used, it was found that specific electrode positions were of great importance for the response. The appliance used in external stimulation have fixed electrode positions.

This means that optimal electrode positions are only obtained by individual adaptation since the anatomy of different individuals varies greatly.

The purpose of the present invention is to provide a device for determination of an oPtimal position of the electrodes where electrical signals can be fed to electrodes with varying positions at the same time as the effect of the stimulation is measured on the urethra, bladder and/or the pelvic floor muscles. Said device does not require any surgical treatment for its application, is easy to insert.

According to the invention, there is provided a testing device for determining the optimal position of electrodes on an electrical stimulator for controlling the urethral, bladder and/or rectal function and being intended to be worn within the vagina or anus, said device comprising an obturator intended to be placed within the vagina or anus, said obturator being provided with a number of electrodes, and a pulse generator arranged to feed stimulating pulses to said electrodes, wherein said electrodes are arranged at a distance from each other aIong the surface of said obturator, and means for making electrical connection between alternative ones of said electrodes and said pulse generator during a measuring course, and measuring equipment for measuring the effect of the stimulation energised on the urethra, bladder and/or the pelvic floor muscles.

The obturator can be made hollow and of a flexible material and so constructed that in an unexpanded state it contains very little air and is therefore simple to insert, after which it is inflated to secure its proper position. It can also be constructed so as to contain a larger amount of air in its unexpanded state. In that case it has to be evacuated before it is inserted, after which it resumes its original volume. By constructing it of a flexible material it will be shaped after the space, in which it is placed, and by this it can be worn without any inconvenience and remains in its proper position. When it is to be taken out it is evacuated again and can be removed without any problem.

The device is also applicable to masculine incontinence, in which case the obturator is inserted into the anus.

The invention will now be described further, by way of example, with reference to the enclosed drawings wherein: Fig. 1 is a longitudinal section through a flexible electrode carrier, Fig. 2 is an axial section through the same electrode carrier, Fig. 3 is a longitudinal section through another flexible electrode carrier, Fig. 4 is a side view of a solid electrode carrier, Fig. 5 is a block scheme of a pulse generator, Fig. 6 is a diagram of urethra-pressure profiles, Fig. 7 shows a coupling device, and Fig. 8 is an outline of two variants of pressure measurement.

An embodiment according to the invention includes an obturator in the form of an inflatable electrode carrier 1 of a flexible material, well tolerated by the tissue, e.g.

silicon rubber. A tube 2 is connected to the electrode carrier. In order not to risk that the tube comes off the carrier 1, when the device is drawn out of the body, the tube 2 can be fastened to the upper as well as lower boundary wall of the electrode carrier 1, as shown in Fig. 1. Another possibility is to put wires of a tensile material into the tube 2.

These wires are fastened to the upper boundary wall 3 of the electrode carrier.

Furthermore, in the tube there is placed an electrical cable 5, whose conductors 6 are connected to one electrode 7 each which are fixed to the electrode carrier 1. As illustrated in Fig. 2, each electrode 7 may be made up of a number, e.g. three, small metal plates 8, electrically connected to each other. The electrodes 7 are located on the same side of the electrode carrier 1 and extend over less than half the circumference of the electrode carrier 1. Thus, when inserted properly, a stimulation directed towards the urethra can be achieved. Other electrode distribution is possible, depending on whether a strictly directed or a diffuse stimulation effect is desired. The arrangement of the electrodes 7 can then comprise a sector of about 80" to 2400. In an alternative arrangement the electrodes are made from a flexible electrically conducting material. In a further alternative arrangement they may be displaceably arranged on the carrier.

At the free end 9 of the tube 2 a nonreturn valve 10 is arranged, that can be opened manually and through which air can be inflated into the electrode carrier 1 and also be evacuated from there. A device 11 for inflation and evacuation, respectively, is indicated in Fig. 1.

The electrode carrier 1 according to the embodiment in Fig. 1 has a thicker wall on the side that carries the electrodes 7. At evacuation of the electrode carrier 1, the thinner wall 12 will thus be curved inwards, while the thicker wall 13, carrying the electrodes 7, will keep its bulged form, and consequently the volume of the electrode carrier 1 is reduced and the insertion made easier. Moreover, the thicker wall 13 serves as a good support to the electrodes 7.

As previously mentioned the electrode carrier 1 is inserted as well as taken out in an evacuated state, while it is preferably filled with air when properly in position.

According to the embodiment in Fig. 1 the electrode carrier 1 is provided with one or more beads 14 on the side which does not carry the electrodes. Otherwise there would be a small risk that the electrode carrier 1 slips out when used by certain patients. This risk can be eliminated by these beads 14, which preferably consist of the same material as the rest of the carrier 1, e.g. silicon rubber.

The electrode carrier 1 shows an essentially plane upper boundary wall 3 at the inner end when applied. In this way an exact position and fixatlon of the electrode carrier 1 can be accomplished in the body, for example in close contact with the uterus portio. This is of the greatest importance in order to obtain a stimulation directed towards the urethra. Instead of a plane upper boundary wall it is possible to have a somewhat curved, that is, somewhat concave or convex, boundary wall.

According to the embodiment in Fig. 3 the electrode carrier 1 has at its lower part, which does not carry any electrodes 7, a thinner wall thickness compared to the upper part. By this a larger bulging of the lower part of the electrode carrier 1 is obtained at the expansion, what is indicated with a dashed line, whereby the electrode carrier can be prevented from slipping out.

The side of the upper part 15 of the electrode carrier, that does not carry the electrodes 7, has a thicker wall than the lower part 16 of the carrier but is thinner compared to the electrode-carrying side.

In Fig. 6 urethra-pressure profiles with some different electrode combinations for a patient are shown, from which it appears that the electrode combination A+E gave the best stimulation effect, while certain other electrode combinations hardly gave any stimulation effect at all. A comparison is then to be made with Fig. 6f, where the urethra-pressure profile is shown without any electrical stimulation at all.

This result is due to the fact that the nerve fibres leading to the urethra muscles and the pelvic floor can be stimulated directly in an afferent direction. Moreover, these nerves conduct impulses in an afferent direction to the spinal cord, and consequently nerve reflexes, effecting the urethra and bladder, are released. These reflex mechanisms are very important in order to restore the continence.

In Figure 5 a pulse generator 17 is shown, the output of which can be varied at least considering the frequency, pulse duration and voltage. The function of this pulse generator will however not be further described.

Thus, when carrying through the test, the different electrodes are connected alternatively to the pulse generator 17 via the coupling device 18, which mainly comprises a number of unipolar three-way switches 19.

A signal with alternating polarity which can be observed on an oscilloscope shown in Figure 7 is then fed to the electrodes 7, at which at least frequency, pulse duration and voltage are varied according to a carefully made up scheme. During the whole testing course the effect of the stimulation, energised on the urethra, is measured and by this it can finally be determined what electrode setting is the optimal one. The pressure, that is exerted by the urethra, can be measured by several different known techniques, for example by an open-flow catheter system, Fig. 8A, or by a miniature pressure transducer catheter system Fig. 8B, by which a so called urethral pressure profile (see Fig. 6) is obtained. As is well known, EMG- measurements can also be used to determine maximum contraction of the muscles concerned. With the open-flow system the catheter has two side holes 21, 22 at some distance from the closed end of the catheter 20. Repeated pressure measurements of urethra profiles can thereby be obtained without removing the catheter from the bladder. A fluid 23 is continuously delivered with about 1 ml/min. A transducer 31 transforms the fluid pressure to an electrical signal which is transmitted to the recorder 27. A urethra pressure profile can also be obtained by using a miniature pressure transducer catheter (see Fig. 8). This catheter 24 is equipped with two transducers 25, 26, placed 50 mm from each other. Thus, bladder pressure as well as urethral pressure could be measured simultaneously. The difference between these pressures is measured and transformed electronically by means of a signal transformer 32. By means of a specifically constructed piece of equipment (not shown) the catheter is withdrawn through the urethra at the rate of 2.5 mmlsec. during all measurements, by which the so called urethra pressure profile is obtained. The withdrawal rate corresponds to the speed of the recorder 27.

In another embodiment according to the invention the electrode carrier 28 comprises a solid cylinder of a homogeneous material, e.g. that known by the Registered Trade Mark Teflon, with a diameter of 20 mm and a length of 75 mm. Seven metal rings A-G of stainless steel, 3 mm wide, constituting the electrodes 7, run round the circumference of said cylinder. At the inner end 29 of the electrode carrier 28, as seen in the applied position, the electrodes 7 are arranged at less distance (about 5 mm) from each other than at the outer end 30 (about 10 mm). This is due to the fact that the position of the electrodes 7 were found to be more critical at the inner part of the vagina.

The seven electrodes 7 of the electrode carrier 28 are connected, as earlier mentioned, in different combinations to the pulse generator 17 in order to determine the optimal position of the electrodes.

WHAT WE CLAIM IS: 1. A testing device for determining the optimal position of electrodes on an electrical stimulator for controlling the urethral, bladder and/or rectal function and being intended to be worn within the vagina or anus, said device comprising an obturator intended to be placed within the vagina or anus, said obturator being provided with a number of electrodes and a pulse generator arranged to feed stimulating pulses to said electrodes, wherein said electrodes are arranged at a distance from each other along the surface of said obturator, and means for making electrical connection between alternative ones of said electrodes and said pulse generator during a measuring course, and measuring equipment for measuring the effect of the stimulation energised on the urethra, bladder and/or the pelvic floor muscles.

2. A device according to claim 1, wherein means are provided for varying the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (15)

**WARNING** start of CLMS field may overlap end of DESC **. lower part of the electrode carrier 1 is obtained at the expansion, what is indicated with a dashed line, whereby the electrode carrier can be prevented from slipping out. The side of the upper part 15 of the electrode carrier, that does not carry the electrodes 7, has a thicker wall than the lower part 16 of the carrier but is thinner compared to the electrode-carrying side. In Fig. 6 urethra-pressure profiles with some different electrode combinations for a patient are shown, from which it appears that the electrode combination A+E gave the best stimulation effect, while certain other electrode combinations hardly gave any stimulation effect at all. A comparison is then to be made with Fig. 6f, where the urethra-pressure profile is shown without any electrical stimulation at all. This result is due to the fact that the nerve fibres leading to the urethra muscles and the pelvic floor can be stimulated directly in an afferent direction. Moreover, these nerves conduct impulses in an afferent direction to the spinal cord, and consequently nerve reflexes, effecting the urethra and bladder, are released. These reflex mechanisms are very important in order to restore the continence. In Figure 5 a pulse generator 17 is shown, the output of which can be varied at least considering the frequency, pulse duration and voltage. The function of this pulse generator will however not be further described. Thus, when carrying through the test, the different electrodes are connected alternatively to the pulse generator 17 via the coupling device 18, which mainly comprises a number of unipolar three-way switches 19. A signal with alternating polarity which can be observed on an oscilloscope shown in Figure 7 is then fed to the electrodes 7, at which at least frequency, pulse duration and voltage are varied according to a carefully made up scheme. During the whole testing course the effect of the stimulation, energised on the urethra, is measured and by this it can finally be determined what electrode setting is the optimal one. The pressure, that is exerted by the urethra, can be measured by several different known techniques, for example by an open-flow catheter system, Fig. 8A, or by a miniature pressure transducer catheter system Fig. 8B, by which a so called urethral pressure profile (see Fig. 6) is obtained. As is well known, EMG- measurements can also be used to determine maximum contraction of the muscles concerned. With the open-flow system the catheter has two side holes 21, 22 at some distance from the closed end of the catheter 20. Repeated pressure measurements of urethra profiles can thereby be obtained without removing the catheter from the bladder. A fluid 23 is continuously delivered with about 1 ml/min. A transducer 31 transforms the fluid pressure to an electrical signal which is transmitted to the recorder 27. A urethra pressure profile can also be obtained by using a miniature pressure transducer catheter (see Fig. 8). This catheter 24 is equipped with two transducers 25, 26, placed 50 mm from each other. Thus, bladder pressure as well as urethral pressure could be measured simultaneously. The difference between these pressures is measured and transformed electronically by means of a signal transformer 32. By means of a specifically constructed piece of equipment (not shown) the catheter is withdrawn through the urethra at the rate of 2.5 mmlsec. during all measurements, by which the so called urethra pressure profile is obtained. The withdrawal rate corresponds to the speed of the recorder 27. In another embodiment according to the invention the electrode carrier 28 comprises a solid cylinder of a homogeneous material, e.g. that known by the Registered Trade Mark Teflon, with a diameter of 20 mm and a length of 75 mm. Seven metal rings A-G of stainless steel, 3 mm wide, constituting the electrodes 7, run round the circumference of said cylinder. At the inner end 29 of the electrode carrier 28, as seen in the applied position, the electrodes 7 are arranged at less distance (about 5 mm) from each other than at the outer end 30 (about 10 mm). This is due to the fact that the position of the electrodes 7 were found to be more critical at the inner part of the vagina. The seven electrodes 7 of the electrode carrier 28 are connected, as earlier mentioned, in different combinations to the pulse generator 17 in order to determine the optimal position of the electrodes. WHAT WE CLAIM IS:

1. A testing device for determining the optimal position of electrodes on an electrical stimulator for controlling the urethral, bladder and/or rectal function and being intended to be worn within the vagina or anus, said device comprising an obturator intended to be placed within the vagina or anus, said obturator being provided with a number of electrodes and a pulse generator arranged to feed stimulating pulses to said electrodes, wherein said electrodes are arranged at a distance from each other along the surface of said obturator, and means for making electrical connection between alternative ones of said electrodes and said pulse generator during a measuring course, and measuring equipment for measuring the effect of the stimulation energised on the urethra, bladder and/or the pelvic floor muscles.

2. A device according to claim 1, wherein means are provided for varying the

electric pulses from the pulse generator at least in terms of the frequency, pulse length and voltage.

3. A device according to claim 1 or 2, wherein the obturator is expandable and is made of a flexible material.

4. A device according to claim 1 or 2, wherein the obturator comprises a solid body.

5. A device according to one or more of the preceding claims, wherein one or any of said electrodes are displaceably arranged on said obturator.

6. A device according to one or more of the preceding claims, wherein each electrode comprises several parts, electrically connected to each other.

7. A device according to one or more of the preceding claims, wherein the electrodes are made of a flexible and conductive material.

8. A device according to one or more of the preceding claims, wherein the obturator has a circular periphery and all electrodes and electrode parts, respectively, are arranged within a sector of the circumference of the obturator, the limiting radii of said sector making an angle of 80-240 with each other.

9. A device according to one or more of the preceding claims, wherein a coupling device is arranged to simultaneously connect two or more electrodes to the pulse generator by means of several unipolar three-way switches.

10. A device according to one or more of the preceding claims, wherein said measuring equipment comprises an openflow catheter system measuring the urethral pressure.

11. A device according to any one of claims 1 to 9 wherein said measuring equipment comprises a miniature pressure transducer catheter system measuring the urethral and bladder pressure.

12. A device according to any one of claims 1 to 9 wherein said measuring equipment comprises an EMGmeasurement device measuring the pressure energised by the urethra and bladder respectively.

13. A testing device substantially as hereinbefore described with reference to and as shown in Figures 1,2, 5, 6, 7 and 8 of the accompanying drawings.

14. A testing device according to claim 1 and substantially as hereinbefore described with reference to and as shown in Figure 3 of the accompanying drawings.

15. A testing device according to claim 1 and substantially as hereinbefore described with reference to and as shown in Figure 4 of the accompanying drawings.