WO2001012089A1 - Nerve stimulation and tissue ablation apparatus and method - Google Patents

Abstract

Apparatus for nerve stimulation and tissue ablation in a patient. A low frequency generator (23) and a high frequency generator (24) are provided. A needle electrode (41) is provided which is adapted to engage the body of the patient. Circuitry couples the needle electrode to the low and high frequency generators sequentially or simultaneously whereby treatment of the patient can be accomplished with the same apparatus.

Description

NERVE STIMULATION AND TISSUE ABLATION APPARATUS AND METHOD

This invention relates to an apparatus and method for nerve stimulation and tissue ablation whereby both diagnostic and treatment modalities are achievable.

Low frequency nerve stimulators previously have been employed to diagnose and evaluate alterations in and abnormalities of the neuromuscular system and/or to precisely locate nerves when operating in the proximity thereof. In addition, nerve stimulation is used peri- operatively in order to evaluate and monitor the response to neuromuscular relaxant and other drugs administered during and after surgical procedures. On the other hand, tissue ablation employs the application of higher frequency energy, often radio-frequency energy, in order to treat neurological and neuromuscular disorders and other anatomical abnormalities or variations by ablating dysfunctional neural or muscle tissue or other redundant or dysfunctional tissue. The evaluation and successful treatment of certain disorders warrants the use of both diagnostic nerve stimulation and therapeutic tissue ablation at the same location, and during the same procedure, within the body. Various approaches for accomplishing this have heretofore been utilized, however, they all have had deficiencies, including the requirement of multiple devices and methods. There is therefore a need for a device capable of both nerve stimulation and tissue ablation in the human body and a method which overcome the deficiencies of prior art devices and methods. In general, it is an object of the present invention to provide a single apparatus and method capable of both nerve stimulation and tissue ablation in the human body for diagnosis and treatment of neurological, neuromuscular and other disorders. Another object of the invention is to provide an apparatus and method of the above character which makes possible the sequential and/or simultaneous application of low frequency energy for nerve stimulation and high frequency energy to ablate tissue. Another object of the invention is to provide an apparatus and method of the above character which are inexpensive, safe and reliable.

Additional objects and features of the invention will appear from the following description in which the preferred embodiment is described in conjunction with the accompanying drawings .

Figure 1 is a block diagram of a nerve stimulation and ablation device incorporating the present invention.

In general, the nerve stimulation and tissue ablation apparatus in the body of a patient having nerves and tissue therein comprises a low frequency generator and a high frequency generator. An energy conducting needle electrode is provided for contacting the body. Means is provided for coupling the energy conducting electrode to the low frequency generator and high frequency generator sequentially or simultaneously to permit location and treatment with the same apparatus.

More specifically, as shown in the drawing, the apparatus 21 of the present invention consists of a first low high frequency generator 23 and a second or high frequency generator 24. The first or low frequency generator 23 provides a low frequency controlled constant current of a frequency ranging 2-50 Hz and, preferably, between 8-12 Hz. The controlled constant current is a very low current in the microamp to milliamp range as for example from 100 microamperes to 50 milliamperes with a voltage ranging from 100 to 200 volts. The generator 23 is powered by a battery supply (not shown) and is capable of supplying a controlled constant current into body impedances ranging from 20 to 40,000 ohms. The second or high frequency generator 24 provides high frequency energy having a frequency greater than 100 Hz and preferably approximately 460 Hz at a power up to 15 watts into an impedance ranging from 10 to 500 ohms. The generator 24 is powered from a plug 26 adapted to be connected to a conventional source of operating power as for example 100- 240 volts AC at 50-60 Hz.

The apparatus 21 consists of a needle electrode 31 formed of a suitable conducting material such as stainless steel which is adapted to be placed in contact with tissue as for example the forehead 36 of a head 37 of a human being 38 as shown in Figure 1.

The needle electrode 31 is mounted in a handle 41 formed of a suitable material such as plastic and is sized to be grasped by the fingers of a human hand as for example the thumb and forefinger. The handle 31 is connected to a flexible cable 42 which carries conductors 43 and 44 with conductor 43 being connected to the needle electrode and conductor 44 being connected to a thermocouple 46 provided at the distal extremity of the needle electrode. Conductor 44 as shown in the drawing is connected to the high frequency generator 24 and serves to ensure that temperature increase being created at the distal extremity of the needle electrode does not exceed a temperature greater than 80°C since the ablation only requires a temperature above 50°C.

The apparatus 21 also includes a return electrode 51 for bipolar operation which is adapted to placed on a suitable location on the body of the patient 39 as for example on the back side of the patient in a convenient location as for example near the neck which is as close as convenient to the site at which the treatment of the present invention is to be performed.

Means is provided for connecting the energy conducting needle electrode 31 to the low frequency generator 23 and the high frequency generator 24 to permit the delivery of a controlled constant current from the low frequency generator 23 and high frequency energy from the high frequency generator 24 sequentially or simultaneously to permit location and treatment with the same apparatus. This means includes a return conductor 52 which is connected to the return electrode 51 and which is connected to the high frequency generator 24 as shown. This return electrode 51 is also connected through a resistor 56 and an inductor 57 to the low frequency power supply 23. The inductor 57 prevents high frequency energy from entering the low frequency generator 23. The low frequency output from the low frequency generator 23 is supplied by a conductor 61 to one end of a switch 62 and the other end of the switch is connected by a conductor 63 to the conductor 43 in the cable 42. The switch 62 can be a switch provided on the case (not shown) containing the generators 23 and 24 and operated by the physician performing the procedure. Alternatively, the switch could be provided in the handle 41 so that it can be opened and closed merely by pressing one of the fingers of the hand holding the handle 41. The output from the high frequency generator 24 is supplied by a conductor 66 to one side of a switch 67 and the other side of the switch 67 is connected by a conductor 68 to one side of a coupling capacitor 71 which will pass the high frequency but not the low frequency from the low frequency power supply 23. The other side of the coupling capacitor 71 is connected by a conductor 72 to the conductor 43. The switch 67 also can be operated in various manners. For example it can be manually controlled by hand. However, this is not as desirable because the physician's hand may be holding the handle 41. For this reason, a foot-asperated pedal 76 has been provided which can be operated by the foot of the physician whose hand is holding the handle 41. Operation and use of the apparatus 21 in performing the method of the present invention to effect nerve stimulation and tissue ablation may now be briefly described as follows. Let it be assumed that a patient has a condition or malady requiring diagnostic nerve stimulation and therapeutic ablation of the nerve sought to be stimulated and the tissue innervated by the nerve and that the procedure is to be performed percutaneously. For example, let it be assumed that the patient has developed a chronically furrowed brow with unsightly or otherwise problematic chronic forehead wrinkles. After appropriate placement of the grounding or return electrode 51 on the patient 39 as hereinbefore described and sedation and/or local or general anesthesia, the portion of the patient's body containing the nerve to be stimulated and the tissue to be ablated is sterilely cleansed and prepared using standard techniques. In treating a furrowed brow, the forehead area 36, including the nasal and superciliary areas, are prepared. After preparation of the patient 39 has been completed, the apparatus 21 can be turned on. The physician grasps the handle 41 with the fingers of one hand and inserts the needle electrode 31 through the skin and into the vicinity of the nerve or nerves sought to be stimulated, as for example terminal branches of the temporal and zygomatic branches of the facial nerve. When the needle electrode 41 has been appropriately placed, the physician closes switch 62 to supply low frequency energy to the tip of the needle electrode 31. When the needle electrode 31 is positioned in close proximity to the specific branches of the temporal and zygomatic branches of the facial nerve, the surrounding orbicularis oculi, procerus and frontalis muscle tissue will begin to twitch and will continue twitching, aggressively furrowing the brow which is visible to the physician. This will indicate to the physician that he or she has located the desired nerve .

Once the physician is confident that he or she has positioned the needle electrode 31 in an appropriate position on or very near the branches of the nerve sought to be ablated as confirmed by an optimal or maximal twitch response to low frequency stimulation, the physician thereafter actuates the foot pedal 76 to close switch 67 to supply high frequency energy to the needle electrode 31. If low frequency energy is concomitantly being supplied to the needle electrode 31, within a short period of time after ablation of the nerve being treated, muscle twitching should disappear and the furrowed brow should relax and forehead wrinkles will disappear. As soon as this occurs it may be assumed that the nerve in question has been successfully ablated and the application of the low frequency energy and the high frequency energy can be terminated by opening switches 62 and 67.

When the physician is confident he or she has ablated the pathological tissue as indicated, he or she simply removes the needle electrode from the patient and, if appropriate, applies a small dressing to the puncture site. It should be appreciated that the procedure may be repeated at the same site or at additional sites in the same manner as hereinbefore described.

If a sequential operation is desired by the physician, the physician can open the switch 62 and thereafter operate the foot pedal 76 to close the switch 67. The physician can thereafter supply radio frequency energy to the needle electrode at a desired power for a desired amount of time which he believes applicable for the application being treated. Thereafter, the physician can operate the foot pedal 76 to open the switch 67. Thereafter the physician can again close the switch 62 to see whether or not with the application of low frequency energy twitching reappears. If not, it can be assumed that the treatment has been successful. If it does, the physician can again terminate the application of low frequency energy by opening the switch 62 and thereafter close the switch 67 to again apply high frequency energy to cause further ablation for a desired period of time at a desired power level. Thereafter, the physician can terminate the application of radio frequency energy to the needle electrode 31 by opening the switch 67. By closing switch 62, the physician again tests the nerve to see whether or not it has been sufficiently ablated by determining whether or not twitching reoccurs. This procedure can be followed until the twitching and furrowing of the brow have ceased upon the application of low frequency energy. The thermocouple senses the temperature during ablation and ensures that excessive temperatures will not be reached as for example greater than 80°C to thereby permit unwanted destruction of tissue during the ablation procedure. If such temperature is reached, the thermocouple will supply information to the radio frequency generator to shut down the radio frequency generator.

It is apparent from the foregoing that there has been provided an apparatus and method for diagnostic nerve stimulation and tissue ablation which can be performed with a single apparatus. With the apparatus and method of the present invention it is possible to perform a procedure with a single needle electrode and applying a low frequency energy and a high frequency energy sequentially or simultaneously as desired by the physician without the necessity of moving the needle electrode until after the desired nerve and its ablation have been accomplished. The apparatus is easy to use. It is inexpensive, safe and reliable.

Claims

WHAT IS CLAIMED:

1. An apparatus for nerve stimulation and tissue ablation in the body of a patient having tissue and herves therein comprising a low frequency generator, a high frequency generator, a needle electrode for contacting the body and means coupling the needle electrode to the low frequency generator and to the high frequency generator sequentially or simultaneously to permit location and treatment with the same apparatus.

2. Apparatus as in Claim 1 wherein the low frequency generator provides energy having a frequency less than 50 Hz and the high frequency generator provides energy having a frequency greater than 100 KHz.

3. Apparatus as in Claim 1 further including temperature sensing means carried by the needle electrode for monitoring and controlling the ablation of tissue.

4. Apparatus as in Claim 3 wherein said temperature sensing means includes a thermocouple carried by said needle electrode.

5. Apparatus as in Claim 1 wherein the means coupling the needle electrode to the low frequency generator and to the high frequency generator sequentially or simultaneously includes a first switch for coupling low frequency energy from the low frequency generator to the needle electrode and a second switch for coupling high frequency energy from the high frequency generator to the needle electrode whereby the first and second switches can be operated sequentially or can be operated at the same time.

6. Apparatus as in Claim 1 wherein said low frequency generator provides a controlled constant current at a voltage ranging from 100 to 200 volts and a low current ranging from 100 microamperes to 50 milliamperes .

7. A method for nerve stimulation and tissue ablation in the body of a patient having tissue and nerves therein by the use of a needle electrode and low frequency energy and high frequency energy comprising the steps of locating the desired nerve by positioning the needle electrode in close proximity to the nerve and supplying low frequency energy to the needle electrode to cause twitching of the nerve visible to the physician, to thereby make it possible for the physician confirm whether or not the appropriate nerve has been located and supplying a radio frequency energy to the needle electrode after termination of the supplying of low frequency energy to the electrode or alternatively at the same time that low frequency energy is being supplied to the needle electrode to ablate the tissue and to thereby ablate the nerve and the tissue enervated by the nerve.

8. A method as in Claim 7 wherein the application of low frequency energy to the needle electrode is terminated prior to the application of high frequency energy to the needle electrode.

9. A method as in Claim 7 wherein the high frequency energy is supplied to the needle electrode during the time that the low frequency energy is being supplied to the needle electrode.

10. A method as in Claim 7 further including the step of monitoring the temperature of the ablation being carried out and terminating the ablation when the temperature of the tissue being ablated exceeds 80°C.

11. A method as in Claim 7 wherein the step of supplying low frequency energy to the needle electrode includes the step of supplying the low frequency energy at a controlled constant current to the needle electrode.

12. A method for treating a patient having chronic forehead wrinkles, the forehead having skin and underlying muscles, said forehead muscles being innervated by branches of the facial nerve, by the application of low frequency and high frequency energy to the branches of the facial nerve and forehead muscle tissue, the method comprising the steps of inserting an energy conducting member through the skin of the forehead, positioning the energy conducting member in close proximity to the branches of the facial nerve, conducting low frequency energy to the energy conducting member in order to confirm that the energy conducting member is positioned in close proximity to said branches of the facial nerve and conducting high frequency energy to the energy conducting member for a predetermined period of time in order to ablate the branches of the facial nerve and forehead muscle tissue innervated by said branches of the facial nerve until said forehead wrinkles are removed.