WO2007085822A1

WO2007085822A1 - Improvements in and relating to peripheral neurostimulation

Info

Publication number: WO2007085822A1
Application number: PCT/GB2007/000237
Authority: WO
Inventors: Teodor Goroszeniuk
Original assignee: Teodor Goroszeniuk
Priority date: 2006-01-25
Filing date: 2007-01-24
Publication date: 2007-08-02
Also published as: GB0701405D0; GB2434539A; GB2434547B; GB0601462D0; GB2434547A

Abstract

A percutaneous stimulating device (10) comprises a self-contained permanent or long- term unit for neuromodulation in the management of chronic pain and for cosmetic applications comprises a stimulating element with one or more electrodes (12), and an integral control unit . The device is in the form of a closed cylinder having a diameter of less than 1.2 to 1.5mm and is no more than 70mm in length so that it can be located and inserted into a patient through a stimulating needle by means of an insertion wire which is may be used to pass a stimulating current to the device to locate it accurately. The stimulating needle and the insertion wire are subsequently withdrawn from the patient when the device is in place. The invention extends to a method for long term pain management by means of neuromodulation using the percutaneous device in accordance with the invention to supply a stimulating signal at between 2 and 50Hz.

Description

IMPROVEMENTS IN AND RELATING TO PERIPHERAL NEUROSTIMULATION

This invention relates to devices for peripheral neurostimulation for the long-term management of chronic pain and for cosmetic applications, and in particular to such percutaneous devices. It also relates to a method for performing such neurostimulation.

Neuromodulation has been established in medical practise since the introduction of peripheral nerve stimulation in 1965 and spinal cord stimulation in 1967. At present some 100,000 units are now implanted in patients around the world (2004). The majority of the implants are carried out for spinal cord stimulation, and similar applications like retrograde, sacral roots or nerve stimulation. Implantable percutaneous devices usually have several discrete elements: an electrode, connections or an extension and a power source. The power to an electrode can be supplied from an external battery by means of a radio frequency (RF) receiver or from internally implanted IPG battery unit.

The use of peripheral neuromodulation technique is expected to expand during this decade. However, the available existing systems are less than satisfactory as they are often quite large and they comprise several separate components. They generally require a surgical procedure to introduce them.

In my earlier patent application GB 2,407,272 1 describe a percutaneous stimulating device for long-term peripheral neuromodulation in pain management and cosmetic applications comprises a stimulating zone with one or more electrodes, and an integral control unit electrically connected to the electrode(s) and capable of supplying an electrical stimulating signal to the electrode(s). The device is formed of an inert material and hermetically sealed and of a substantially cylindrical form so dimensioned as to be suitable for insertion into a patient through a stimulating needle. In accordance with the present invention, an insertion wire is attached to the outer end of the stimulating device and extends outwardly from the outer end of the stimulating needle is arranged so that in use it can be used to fine tune the positioning of the stimulating device once it has been inserted into the patent. The wire is arranged so that once the device is located it can be disconnected from the device, which remains in place, and withdrawn from the patient with the stimulating needle.

The insertion wire may also optionally be used to provide an electrical contact with the stimulating device permitting the electrodes to be used to provide electrical stimulation so that the device can be accurately located before the insertion wire is withdrawn, leaving the stimulating device in place.

In practice, a skilled practitioner will use an external stimulating probe to locate the area where pain relief by electro-stimulation is to be applied. In some cases treatment may be possible by means of external stimulation alone by applying the stimulating signal externally so that it passes through the skin to the affected area. In more severe cases to which this invention relates, the area is accurately located by means of a stimulating needle inserted through the skin. A signal is then applied through the tip of the needle to locate the region of the affected nerve or muscle.

In the present invention the insertion wire is stiff enough to allow it to be used as a means to push or move the device to position the electrodes at the optimum stimulating location. The insertion wire may also be used to provide an electrical connection to the stimulating device both for location of the device and/or for setting the parameters of the signal applied to the electrodes to treat the pain.

Where the insertion wire is used to provide the stimulating signal to the stimulating device during its location, it needs to be insulated to avoid the current from leaking to the surrounding tissue. The insertion wire can also comprise a pair of conductors so that the signal is applied through the electrodes which form part of the stimulating device; in a simpler form, the insertion wire will comprise a single conductor so that the electrical reference is provided by means of a patch which is used to provide the reference contact for the stimulating needle. The percutaneous introduction of such a semi-permanent device for peripheral neuromodulation by means of the stimulating needle and located by means of the insertion wire considerably simplifies the procedures on patients and allows them to be carried out by other than by invasive surgery. A small incision may nevertheless be required to access a withdrawal loop if one is provided. This procedure also minimises any surgical trauma resulting from the insertion of this type of unit. The use of the insertion wire to move and adjust the stimulating device permits a level of accuracy in positioning the device hitherto difficult to achieve and thus greatly enhances the efficacy of the device and the resulting pain relief.

The device is thus intended to remain in place permanently, or at least for many weeks or months which is made possible either by the use of suitable long-life or rechargeable batteries, or by means of a radio frequency (RF) signal to the implanted device. In one embodiment the RF signal is arranged to recharge the battery to give the patient autonomy from using an external unit. In another embodiment the RF signal is converted to the required amplitude and frequency within the stimulating device and applied to the electrode(s). It is thus possible to apply the RF output directly to control the electrodes and/or to provide the energy for the device.

The diameter of the device will not be greater than 2mm and preferably 1.5mm, and ideally less than 1.2mm to permit its insertion through a stimulating needle. It will be less than 70mm long so that it can be inserted through a normal stimulating needle, and preferably less than 40mm, though for cosmetic applications shorter versions of less than 20mm or even as short as 6mm may be required. As electronic components become smaller even smaller versions may become feasible, and the cost of the device is likely to decrease significantly.

Whilst the electrodes and their associated electronic controls are small enough to permit insertion through a stimulating needle, the power supply which forms a part of the device may be chosen from a selection of different models in order to suit the application and the patient's needs. In a preferred embodiment the power supply is detachable from the stimulating element of the device allowing a practitioner to select a suitable power supply which can be attached to the stimulating element by means of a screw thread, clip or other means. Thus, a choice may be made between long-life batteries, rechargeable batteries or an RF unit.

In order to accommodate the power requirements and the desired autonomy it may be necessary, at present, for the battery or the RF unit to be too wide or bulky for it to be inserted through a stimulating needle. If this is the case, the stimulating element of the device may be inserted first through the stimulating needle and the battery or RF unit to be attached to the stimulating element in situ after it has been inserted and located (using a signal passed along the insertion wire). Such attachment and implantation of the power supply to the stimulating element may however require a small incision.

The preferred stimulation frequency range of the device is between 1 and 50Hz and optimally between 2 and 10Hz. This low frequency has a particularly beneficial effect on the treatment of chronic pain. A current of between 0.15 and 15 mA and preferably between 2 and 10 mA is found to be very successful. In general a square wave is used and the wave duration is typically from 0.5 to 1 ms though it may be as short as 0.05 ms, or as long as 10 or 12 ms depending on the extent and the severity of the pain to be treated, and the response of the patient to the treatment.

As the device may fail, or otherwise need to be removed it is conveniently be provided with a drawstring at the end opposite to the stimulating zone to enable it to be removed from a patient if required without the need for a surgical procedure, although a small incision may be necessary. The draw-string is ideally opaque to X- rays to facilitate its location.

A stimulating needle ready for percutaneous insertion into a patient is intended in practice to be supplied as an assembly with the insertion wire attached to the stimulating device already inside the needle and with all the necessary electrical connections.

The invention extends equally to a method of treating chronic pain by identifying the location to be treated by inserting a stimulating needle connected to an appropriate external stimulating source, applying a stimulating current or signal, and then inserting a miniature stimulating device or capsule through the needle. The position of the miniature stimulating device is fine tuned by means of a rigid or semi-rigid wire connected to it and allowing it to be moved while a stimulating signal is passed down the wire or while the device itself is activated.

The invention will now be described specifically by way of example with reference to the accompanying drawing marked Figure 1 which is a diagrammatic view of a percutaneous stimulating device in accordance with the invention in the process of being inserted into a patient.

A percutaneous stimulating device 10 for long-term peripheral neuromodulation in pain management and cosmetic applications comprises a stimulating element 12 with one or more pairs of electrodes including an integral control unit powered by a power supply 14. The integral control unit is arranged to supply an electrical stimulating signal to the electrodes. The electrodes 12 may either be arranged as pairs of electrodes or as a number of stimulating electrodes with one or more reference electrodes. The device is formed of an inert material and hermetically sealed and of a substantially cylindrical form so dimensioned as to be suitable for insertion into a patient through a stimulating needle 16.

A semi-rigid insertion wire 18 attached to the outer end of the device 10 and extending outwardly from the outer end of the stimulating needle 16 is arranged so that in use it can be used to fine tune the positioning of the stimulating device. The wire 18 is formed so that once the device is located in a patient it can be disconnected from the device which remains in place. The wire 18 is then withdrawn with the needle. The entry point of the insertion wire into the stimulating device is self-sealing maintain a hermetic seal of the device.

The stimulating device 10 is a self-contained permanent or long-term unit for neuromodulation in the management of chronic pain and for cosmetic applications. An integral control unit 14 with a power supply is built into the outer end of the stimulating device and is capable of supplying an electrical stimulating signal to the electrodes 12 over a prolonged period of many months.

The body of the device is generally cylindrical having a diameter of 1.2 to 1.5mm. It is between 20 and 70mm in length depending on its intended application. For facial or cosmetic applications however it may be as short as 6mm.

In use, the stimulating needle 16 is electrically connected to an external locating stimulator 20 by a lead 22 which is supplied with the stimulating needle ready for connection to the locating stimulator 20. A patch 24 is also connected to the locating stimulator 20 by a wire 28 and stuck to the skin 30 of a patient to make an electrical contact as a reference electrode. In most cases an external locating device will have been used to provide an initial location of the area to be treated.

The locating stimulator 20 is than set to provide a low-level signal to the stimulating needle 22 which is inserted into the patient. The patient feels a beneficial effect as the signal at the uninsulated end 32 of the needle as it nears the affected area. When practitioner is satisfied that the needle is suitably located, he introduces the stimulating device 10 by pushing it through the stimulating needle 16 by means of the insertion wire 18.

The stimulating device is then activated and the final adjustment of its location is made by means of the insertion wire 18 so that the electrodes 12 on the stimulating device are optimally placed to treat the pain while a signal is transmitted through the wire or the device itself is activated to send a signal to the electrodes. Equally, fine tuning of the stimulating signal in terms of power (mA), frequency and pulse duration may be adjusted by a practitioner in response to the patient.

The stimulating signal, during location of the stimulating device 10, can either be supplied from the locating stimulator 20 to the stimulating device through the insertion wire 18 and the patch 28, by means of its own battery or by an external RF device (not shown). The frequency and the intensity of the signal supplied to the tip 32 of the stimulating needle, or to the electrodes on the stimulating device can be adjusted on the stimulating locator 20 by standard means, from say 1 to 20 Hz and from 0.1 to 15mA though more usually less than 10mA, as required to produce the optimum level of relief. Typically the signal is of a square waveform and has a duration of 0.5 to 1 ms of each cycle. The actual values will be determined by a skilled practitioner according to the location, extent and severity of the pain to be treated, and will depend on the response of the patient to the treatment.

As a general guide, the applied current will depend on the severity of the pain and the duration of the pulse, ie. the applied energy, will be determined by the extent of the pain to be treated. The frequency is selected by the practitioner in response to feedback from the patient on their preferences and the effectiveness of the treatment. In most cases the patient will indicate a preference for a frequency of 2 to 10 Hz.

The device is thus intended to remain in place permanently, or at least for many weeks or months which is made possible either by the use of suitable long-life or rechargeable batteries, or by means of a radio frequency (RF) signal to a transformer forming part of the control unit on the stimulating device. In one embodiment the battery receives its charge from an external RF unit to give the patient autonomy from always having to use an external unit when treatment is required. In another embodiment the stimulating device 10 receives its charge from an external RF source and converts the signal to the required amplitude and frequency for the electrodes. It is also possible to apply the RF output directly to control the electrodes and/or to provide the energy for the device.

As the device has a finite life and sooner or later will need to be removed, it is provided with a draw-string 36 which is buried under the skin with the device. The draw-string has a loop 38 at its outer end and is opaque to X-rays so that it can be easily located to allow the device to be removed after making a small incision.

It is anticipated that as electronic components decrease in size it will be possible to manufacture the device in ever shorter lengths, viz. shorter than 20mm or even less than 10mm. Very small devices which may be no longer than 6mm lend themselves particularly to cosmetic treatments, and to facial implants. Longer devices may be used for areas where a larger area of treatment is required, such as wrists, shoulder or the back.

Whilst the electrodes and their associated electronic controls are small enough to permit insertion through a stimulating needle, the power supply which forms a part of the device may be chosen from a selection of different models in order to suit the application and the patient's needs. The power supply is thus detachable from the stimulating element of the device with the electrodes allowing a practitioner to select a suitable power supply which can be attached to the stimulating element by means of a screw thread, clip or other means. In practice this has the advantage of allowing the practitioner to make a choice between long-life batteries, rechargeable batteries or an RF unit as best to suit a patient's needs.

In order to accommodate the power requirements and the desired autonomy it may be necessary, at present, for the battery or the RF unit to be too wide or bulky for it to be inserted through a stimulating needle. If this is the case, the stimulating element of the device with the electrodes 12 may be inserted first through the stimulating needle and the battery or RF unit to be attached to the stimulating element in situ after it has been inserted. The electrodes may nevertheless still be located by using a signal passed along the insertion wire. Such attachment and implantation of the power supply to the stimulating element may however require a small incision.

The percutaneous device is placed in its desired position by applying a suitable signal to a stimulating needle and preferably through the device itself as described above. A specialist doctor or practitioner determines the area of implantation and the ranges of the stimulating frequency and current. Where there is an RF connection between the device and an external unit the patient has a greater choice of use of the device to provide relief. He or she will also be able to vary the frequency and current within the parameters preset by the specialist practitioner to obtain optimum relief.

Claims

1. A percutaneous stimulating device for long-term peripheral neuromodulation in pain management and for cosmetic applications comprising a stimulating element with at least one pair of electrodes, and a control unit electrically connected to the electrodes and capable of supplying an electrical stimulating signal to the electrodes, the device being formed of an inert material and hermetically sealed and of a substantially cylindrical or ovaloid form so dimensioned as to be suitable for insertion into a patient through a stimulating needle in which the device is arranged to be used with a removable, rigid or semi-rigid insertion wire to enable it to be inserted percutaneously through the stimulating needle and its position to be adjusted as required.

2. A stimulating device as claimed in claim 1 in which the insertion wire is an electrical conductor, arranged to be connected electrically to the device to enable an electrical signal to be transmitted to the said electrodes.

3. A stimulating device as claimed in claim 1 or 2 in which the insertion wire is electrically insulated along its length to prevent electrical contact with the patient's skin during insertion of the device.

4. A stimulating device as claimed in any preceding claim in which the insertion wire comprises twin conductors, each insulated from the other and making an electrical connection with the device.

5. A stimulating device as claimed in any preceding claim in which the connection with the device is arranged to be sealed hermetically on removal of the insertion wire.

6. A stimulating device as claimed in any preceding claim in which the device is provided with a power supply which is either a long-life battery, a rechargeable battery or a transformer arranged to receive an external RF signal.

7. A stimulating device as claimed in claim 6 in which the power supply is detachable from the stimulating element of the device allowing an appropriate battery or transformer to be hermetically attached to the stimulating element.

8. A stimulating device as claimed in any preceding claim in which the device is provided with a draw-string to enable it to be removed at the end of its useful life.

9. A stimulating device as claimed in claim 8 in which the draw-string is of a material that is opaque to X-rays to allow it to be easily detected under the skin when in use.

10. A stimulating device as claimed in any preceding claim whose diameter is not greater than 1.5mm, and preferably less than 1.2mm.

11. A stimulating device as claimed in any preceding claim in which stimulation frequency range is between 1 and 20Hz, preferably between 2 and 10Hz.

12. A stimulating device as claimed in any preceding claim in which the stimulating current is between 2 and 2OmA₅ preferably between 2 and 10mA.

13. A stimulating device as claimed in any preceding claim in which the control unit in the device is arranged to receive a radio frequency (RF) signal from an external controller and to apply it in the required amplitude and frequency to the electrode(s).

14. A stimulating device as claimed in any preceding claim in which the device is supplied within a stimulating needle ready for insertion into a patient.

15. A stimulating device for long-term pain management and cosmetic applications by means of peripheral neuromodulation as claimed in any preceding claim and substantially as herein described with reference to the accompanying drawing.

16. A method for long-term pain management and for cosmetic applications by means of percutaneous peripheral neuromodulation by inserting a neurostimulation device comprising one or more pairs of electrodes and an integral electronic control unit capable of supplying an electrical stimulating signal to the electrodes through a stimulating needle and accurately locating the device by means of the stimulating needle.

17. A method as claimed in claim 16 in which the device is finely positioned mechanically by using a rigid or semi-rigid insertion wire to locate the device in an optimum position in the zone to be stimulated by the device.

18. A method as claimed in claim 17 in which the stimulating signal to the device is passed through the insertion wire to the stimulating device in order to optimise its location.

19. A method as claimed in any of claims 16 to 18 in which the stimulation frequency applied by the device to the patient is in the range between 2 and 10Hz.

20. A method as claimed in any of claims 16 to 19 in which the stimulation current applied by the device to the patient is in the range between 2 and 10mA.

21. A method for long-term pain management and cosmetic applications by means of percutaneous peripheral neuromodulation as claimed in any of claims 16 to 20 and substantially as herein described with reference to the accompanying drawing.