ABLATION APPARATUS AND SYSTEM TO LIMIT NERVE CONDUCTION
An electrosurgical probe including a probe body which defines a longitudinal probe axis. The electrosurgical probe also includes a first and second conductive electrode, each disposed along the probe axis. The surface area of the first conductive electrode is greater of the surface area of the second conductive electrode. The ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode may be adjustable. Another aspect of the present invention is an electrosurgical probe having a probe body which defines a single longitudinal probe axis. The electrosurgical probe of this aspect of the invention further includes more than two electrodes operatively disposed at separate and distinct positions along the axis of the probe body. The electrodes may be selectively connected to one of or a combination of a stimulation energy source, an ablation energy source or a ground for either energy source. Another aspect of the present invention is a method of placing an electrosurgical probe such as described above for specific ablation procedures.
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This application is a continuation-in-part of U.S. application Ser. No. 10/870,202, filed Jun. 17, 2004, entitled “Ablation apparatus and system to limit nerve conduction,” now published, which is hereby incorporated by reference.
TECHNICAL FIELDThe present invention relates to a method and device used in the field of Minimally Invasive Surgery (or MIS) for interrupting the flow of signals through nerves. These nerves may be rendered incapable of transmitting signals either on a temporarily (hours, days or weeks) or a permanent (months or years) basis. One embodiment of the apparatus includes a single puncture system which features electrodes capable of creating areas of nerve destruction, inhibition and ablation.
BACKGROUND OF THE INVENTIONThe human nervous system is used to send and receive signals. The pathway taken by the nerve signals conveys sensory information such as pain, heat, cold and touch and command signals which cause movement (e.g. muscle contractions).
Often extraneous, undesired, or abnormal signals are generated (or are transmitted) along nervous system pathways. Examples include, but are not limited to, the pinching of a minor nerve in the back, which causes extreme back pain. Similarly, the compression or other activation of certain nerves may cause referred pain. Certain diseases also may compromise the lining of nerves such that signals are spontaneously generated, which can cause a variety of maladies, from seizures to pain or (in extreme conditions) even death. Abnormal signal activations can cause many other problems including (but not limited to) twitching, tics, seizures, distortions, cramps, disabilities (in addition to pain), other undesirable conditions, or other painful, abnormal, undesirable, socially or physically detrimental afflictions.
In other situations, the normal conduction of nerve signals can cause undesirable effects. For example in cosmetic applications the activation of the corrugator supercilli muscle causes frown lines which may result in permanent distortion of the brow (or forehead); giving the appearance of premature aging. By interruption of the corrugator supercilli activation nerves, this phenomenon may be terminated. Direct surgical interruption of nerves is however a difficult procedure.
Traditional electrosurgical procedures use either a unipolar or bipolar device connected to that energy source. A unipolar electrode system includes a small surface area electrode, and a return electrode. The return electrode is generally larger in size, and is either resistively or capacitively coupled to the body. Since the same amount of current must flow through each electrode to complete the circuit; the heat generated in the return electrode is dissipated over a larger surface area, and whenever possible, the return electrode is located in areas of high blood flow (such as the biceps, buttocks or other muscular or highly vascularized area) so that heat generated is rapidly carried away, thus preventing a heat rise and consequent burns of the tissue. One advantage of a unipolar system is the ability to place the unipolar probe exactly where it is needed and optimally focus electrosurgical energy where desired. One disadvantage of a unipolar system is that the return electrode must be properly placed and in contact throughout the procedure. A resistive return electrode would typically be coated with a conductive paste or jelly. If the contact with the patient is reduced or if the jelly dries out, a high-current density area may result, increasing the probability for burns at the contact point.
Typical bipolar electrode systems are generally based upon a dual surface device (such as forceps, tweezers, pliers and other grasping type instruments) where the two separate surfaces can be brought together mechanically under force. Each opposing surface is connected to one of the two source connections of the electrosurgical generator. Subsequently, the desired object is held and compressed between the two surfaces. When the electrosurgical energy is applied, it is concentrated (and focused) so that tissue can be cut, desiccated, burned, killed, stunned, closed, destroyed or sealed between the grasping surfaces. Assuming the instrument has been designed and used properly, the resulting current flow will be constrained within the target tissue between the two surfaces. One disadvantage of a conventional bipolar system is that the target tissue must be properly located and isolated between these surfaces. Also, to reduce extraneous current flow the electrodes can not make contact with other tissue, which often requires visual guidance (such as direct visualization, use of a scope, ultrasound or other direct visualization methods) so that the target tissue is properly contained within the bipolar electrodes themselves, prior to application of electrical energy.
In recent years, considerable efforts have been made to refine sources of RF or electrical energy, as well as devices for applying electrical energy to specific targeted tissue. Various applications such as tachyarrhythmia ablation have been developed, whereby accessory pathways within the heart conduct electrical energy in an abnormal pattern. This abnormal signal flow results in excessive and potentially lethal cardiac arrhythmias. RF ablation delivers electrical energy in either a bipolar or unipolar configuration utilizing a long catheter, similar to an electrophysiology (EP) catheter. An EP catheter consisting of a long system of wires and supporting structures normally introduced via an artery or vein which leads into the heart is manipulated using various guidance techniques, such as measurement of electrical activity, ultrasonic guidance, and/or X-ray visualization, into the target area. Electrical energy is then applied and the target tissue is destroyed.
A wide variety of technology in the development of related systems, devices and EP products has already been disclosed. For example, U.S. Pat. No. 5,397,339, issued Mar. 14, 1995, describes a multipolar electrode catheter, which can be used to stimulate, ablate, obtain intercardiac signals, and can expand and enlarge itself inside the heart. Other applications include the ability to destroy plaque formations in the interior of lumens within the body; using RF energy applied near, or at the tip of, catheters such as described in U.S. Pat. No. 5,454,809 and U.S. Pat. No. 5,749,914. In these applications a more advanced catheter which is similar to the EP catheters described above contains an array of electrodes that are able to selectively apply energy in a specific direction. Such devices allow ablation and removal of asymmetric deposits or obstructions within lumens in the body. U.S. Pat. No. 5,098,431 discloses another catheter based system for removing obstructions from within blood vessels. Parins, in U.S. Pat. No. 5,078,717 discloses yet another catheter to selectively remove stenotic lesions from the interior walls of blood vessels. Auth in U.S. Pat. No. 5,364,393 describes a modification of the above technologies whereby a small guide wire which goes through an angioplasty device and is typically 110 cm or longer has an electrically energized tip, which creates a path to follow and thus guides itself through the obstructions.
In applications of a similar nature, catheters which carry larger energy bursts, for example from a defibrillator into chambers of the heart have been disclosed. These catheters are used to destroy both tissues and structures as described in Cunningham (U.S. Pat. No. 4,896,671).
Traditional treatments for the elimination of glabellar furrowing have included surgical forehead lifts, resection of corrugator supercilli muscle, as described by Guyuron, Michelow and Thomas in Corrugator Supercilli Muscle Resection Through Blepharoplastylncision., Plastic Reconstructive Surgery 95 691-696 (1995). Also, surgical division of the corrugator supercilli motor nerves is used and was described by Ellis and Bakala in Anatomy of the Motor Innervation of the Corrugator Supercilli Muscle: Clinical Significance and Development of a New Surgical Technique for Frowning., J Otolaryngology 27; 222-227 (1998). These techniques described are highly invasive and sometimes temporary as nerves regenerate over time and repeat or alternative procedures are required.
More recently, a less invasive procedure to treat glabellar furrowing involves injection of botulinum toxin (Botox) directly into the muscle. This produces a flaccid paralysis and is best described in The New England Journal of Medicine, 324:1186-1194 (1991). While minimally invasive, this technique is predictably transient; so, it must be re-done every few months.
Specific efforts to use RF energy via a two needle bipolar system has been described by Hernandez-Zendejas and Guerrero-Santos in: Percutaneous Selective Radio-Frequency Neuroablation in Plastic Surgery, Aesthetic Plastic Surgery, 18:41 pp 41-48 (1994) The authors described a bipolar system using two parallel needle type electrodes. Utley and Goode described a similar system in Radio-frequency Ablation of the Nerve to the Corrugator Muscle for Elimination of Glabellar Furrowing, Archives of Facial Plastic Surgery, January-March, 99, VI P 46-48, and U.S. Pat. No. 6,139,545. These systems were apparently unable to produce permanent results possibly because of limitations inherent in a two needle bipolar configuration. Thus, as is the case with Botox, the parallel needle electrode systems would typically require periodic repeat procedures.
There are many ways of properly locating an active electrode near the target tissue and determining if it is in close proximity to the nerve. Traditional methods in the cardiac ablation field have included stimulation by using either unipolar and bipolar energy by means of a test pacemaker pulse prior to the implantation of a pacemaker or other stimulation device. A method of threshold analysis called the ‘strength duration curve’ has been used for many years. This curve consists of a vertical axis (or Y-axis) typically voltage, current, charge or other measure of amplitude, and has a horizontal axis (or X-axis) of pulse duration (typically in milliseconds). Such a curve is a rapidly declining line, which decreases exponentially as the pulse width is increased.
Various stimulation devices have been made and patented. One process of stimulation and ablation using a two-needle system is disclosed in U.S. Pat. No. 6,139,545. The stimulation may also be implemented negatively, where tissue not responsive to stimulation is ablated as is described in U.S. Pat. No. 5,782,826 (issued Jul. 21, 1998).
SUMMARY OF THE INVENTIONOne aspect of the present invention is an electrosurgical probe including a probe body which defines a longitudinal probe axis. Thus the probe resembles a single needle and can be placed into tissue through a single opening. The electrosurgical probe also includes a first and second conductive electrode, each disposed along the probe axis. The surface area of the first conductive electrode is, in this aspect of the invention, greater than the surface area of the second conductive electrode. The ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode may be equal to or greater than 3:1 or equal to or greater than 8:1. The ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode may be adjustable.
The electrosurgical probe of the subject invention may further include a stimulation energy source in electrical communication with either the first or the second conductive electrode. Similarly, the electrosurgical probe may also include an ablation energy source communicating with either the first or second conductive electrode. A switch may be provided for the selective connection of the stimulation energy source or the ablation energy source to at least one of the conductive electrodes. Either the first or the second conductive electrode may be nearer the point of the electrosurgical probe at one end of the probe axis.
Another aspect of the present invention is an electrosurgical probe including a probe body defining a longitudinal probe axis, an active electrode operatively associated with the probe body at a first location along the probe axis, a stimulation electrode associated with the probe body at a second location along the probe axis and a return electrode operatively associated with the probe body at a third location along the probe axis. The stimulation electrode may be positioned between the active and return electrodes. The electrosurgical probe of this embodiment may further include a stimulation energy source in electrical communication with the stimulation electrode. The stimulation energy source may provide variable stimulation current. Either the active electrode, the return electrode or both may be connected to a ground for the stimulation energy source. Alternatively, a separate ground may be employed. This aspect of the present invention may also include an ablation energy source connected to the active electrode. The ablation energy source may be configured to provide variable ablation energy.
Another aspect of the present invention is an electrosurgical probe also having a probe body defining a longitudinal probe axis. At least three electrodes will be associated with the probe body at distinct and separate locations along the probe axis. A stimulation energy source connected to at least one of the electrodes is also included.
The stimulation energy source of this embodiment of the present invention may be configured to provide variable stimulation energy. In addition, the stimulation energy source may be selectively connected by means of a switch to at least one or more of the various electrodes. Similarly, a ground for the stimulation energy source may be selectively connected to one or more of the electrodes.
Another aspect of the present invention is a method for positioning an electrosurgical probe. The method includes providing an electrosurgical probe such as those described immediately above, inserting the electrical surgical probe to a first position within tissue containing a target nerve and applying stimulation energy to an electrode. Upon the application of stimulation energy, a first response of a muscle associated with the target nerve may be observed. Thereupon, the electrosurgical probe may be moved to a second position and a second application of stimulation energy may be undertaken. The method further includes observing a second response of a muscle associated with the target nerve and comparing the second response with the first response. The method may also include varying the level of stimulation energy between the first and second applications of stimulation current. If the electrosurgical probe provided to implement the method has a third electrode, stimulation energy may be applied to a select third electrode as well. Certain advantages will be observed with respect to positioning the electrosurgical probe if stimulation energy is sequentially applied to first, second, third and subsequent electrodes.
BRIEF DESCRIPTION OF THE DRAWINGS
Certain terms used herein are defined as follows:
Medical Terms
Corrugator supercili muscles—skeletal muscles of the forehead that produce brow depression and frowning.
Cepressor anguli oris—skeletal muscle of the corner of the mouth that produces depression of the corner of the mouth.
Depressor labii inferioris—skeletal muscle of the lower lip that causes the lip to evert and depress downward.
Dystonias—medical condition describing an aberrant contraction of a skeletal muscle which is involuntary.
Frontalis—skeletal muscle of the forehead that produces brow elevation or raising of the eyebrows.
Hyperhidrosis—condition of excessive sweat production.
Masseter—skeletal muscle of the jaw that produces jaw closure and clenching.
Mentalis—skeletal muscle of the lower lip and chin which stabilizes lower lip position.
Orbicularis oculio—skeletal muscle of the eyelid area responsible for eyelid closure.
Orbicularis ori—skeletal muscle of the mouth area responsible for closure and competency of the lips and mouth.
Parasymapathetic—refers to one division of the autonomic nervous system.
Platysma myoides—skeletal muscle of the neck that protects deeper structures of the neck.
Platysma—same as above.
Procerus muscles—skeletal muscle of the central forehead responsible for frowning and producing horizontal creasing along the nasofrontal area.
Procerus—same as above.
Rhinorrhea—excessive nasal mucous secretions.
Supercilli—a portion of the corrugator muscle that sits above the eyelids.
Temporalis—skeletal muscle of the jaw that stabilized the temporamandibular joint.
Zygomaticus major—skeletal muscle of the face that produces smiling or creasing of the midface.
Electrical Terms.
ADC: Analog to digital converter.
ASCII: American standard of computer information interchange.
BAUD: Serial communication data rate in bits per second.
BYTE: Digital data 8-bits in length.
CHARACTER: Symbol from the ASCII set.
CHECKSUM: Numerical sum of the data in a list.
CPU: Central processing unit.
EEPROM: Electronically erasable programmable read only memory.
FLASH MEMORY: Electrically alterable read only memory. (See EEPROM)
UI: Graphical user interface.
HEXADECIMAL: Base 16 representation of integer numbers.
12C BUS: Inter Integrated Circuit bus. Simple two-wire bidirectional serial bus developed by Philips for an independent communications path between embedded ICs on printed circuit boards and subsystems.
The I2C bus is used on and between system boards for internal system management and diagnostic functions.
INTERRUPT: Signal the computer to perform another task.
PC: Personal computer.
PWM: Pulse-width modulation.
ROM: Read only memory.
WORD: Digital data 16-bits in length
DETAILED DESCRIPTION OF THE INVENTION
In normal operation, the novel probe 371 would combine a unique bipolar configuration in a single MIS needle, is inserted into the patient using MIS techniques. The probe, which may contain and/or convey various functions described later, is initially guided anatomically to the region of the anticipated or desired location. Various means of locating the tip 301 are utilized of placing the zone of ablation in the proper area to interrupt signal flows through the nerve 101.
Device Operation
Many combinations of electrode diameters and tip shapes are possible. The ‘novel’ probe performs a variety of functions, such as stimulation, optical and electronic guidance, medication delivery, sample extraction, and controlled ablation. This bi-polar electrode is designed as a small diameter needle inserted from a single point of entry thus minimizing scaring and simplifying precise electrode placement. This low cost, compact design provides a new tool to the art.
Probes may emit fiber optic illumination for deep applications using electronic guidance as taught in
Stimulation/Ablation
First the probe electrode 301 must be in the desired location relative to the target nerve 101 (
For example, both a high amplitude sine wave 910 (
The output of the modulator 415 is applied to the input of the power amplifier 416 section. The power amplifier's 416 outputs are then feed into the impedance matching network 418, which provides dynamic controlled output to the biologic loads that are highly variable and non-linear, and require dynamic control of both power levels and impedance matching. The tuning of the matching network 418 is performed for optimal power transfer for the probe, power level, and treatment frequencies settled. The system's peak power is 500 watts for this disclosed embodiment. Precise control is established by the proximity of the tip and the control loops included in the generator itself The final energy envelope 420 is delivered to probe tip 301 and return electrodes 302.
This precise control of energy permits extension of the ablation region(s), 140 and 1203 (
A low energy nerve stimulator 771 has been integrated into the system to assist in more precise identification of nearby structures and for highly accurate target location. Lastly, additional sensors, such as temperature 311, voltage, frequency, current and the like are read directly from the device and/or across the communications media 403 to the probe.
Directed Ablation
In addition to the substantial radially-symmetric ablation patterns with probes as taught in 371 (
Power Feedback
The power amplifier output430 and buffered the feedback signals 437 are connected to an Analog to Digital converter (or ADC) 431 for processor analysis and control. Said signals 437 control power modulation 420 settings and impact the impedance matching control signals 419. This integrated power signal 437 is recorded to the operating-condition database (
Probe Identification
At power startup, the controller 401(
The controller 401 also verifies selected procedure 1415 (
Nerve Target Location Tools
Prior to treatment, the practitioner may use auxiliary probe 771(
Location Via Florescence Marker Dye.
In other procedures, whereby somewhat larger targets are sought, such as more diffuse nerve structures or small areas of abnormal growth (e.g. such as cancer) the injection of specially designed dyes that attach to target structures are used, as taught in
Electronic Probe Guidance
Low energy nerve stimulation current 810 (
Optical Probe Guidance
Disclosed invention provides optical sources 408 that aid in probe placement (
Data and Voice
Real-time engineering parameters are measured such as average power 437, luminous intensity 478, probe current 811, energy 438 and, temperature 330 to be recoded into USB memory 438. Simultaneously, the internal parameters disclosed such as frequency 423, modulation 420 and such are recoded into USB memory 438 as well. Additionally probe, patient, and procedure parameters (
Data Transfer
At procedure conclusion, the system transfers the data 438 recorded to the USB removable memory 1338 and to a file server(s) 1309 and 1307. In the disclosed embodiment, data transfer is performed over Ethernet connection 480. Probe usage records 1460(
Before further explaining the disclosed embodiment of the present invention in detail, it is to be understood that the invention is not limited in its application or to the details of the particular arrangement shown. The invention is capable of other embodiments. Further, the terminology used herein is for the purpose of describing the probe and its operation. Each apparatus embodiment described herein has numerous equivalents.
Bi-polar probe 310 represents probes 371, 372, 373 shown in FIGS. 3A-C with exception to type of needlepoint on the probe.
Hollow Electrode 301 often used as a syringe to deliver medication such as local anesthetic. Tip electrode 301 is connected to power amplifier 416 via impedance matching network 418 (
Ablation regions 306 and 140 extend radially about electrode 301 generally following electric field lines. For procedures very close to skin 330 a chance of burning exists in region 306. To minimize the chance of burning, a split return electrode probe 374 in
The bi-polar probe 380 (not drawn to scale) consists of an insulating dielectric body 309 made from a suitable biologically inert material, such as Teflon PTFE or other electrical insulation, that covers split return electrodes 302 and 303. The disclosed conductive return electrodes 302 and 303 are fabricated from medical grade stainless steel, titanium or other electrically conductive material. Hollow or solid split conductive tip electrodes 301 and 311 protrude from the surrounding dielectric insulator 305. The operation of the hollow/split conductive tip is very similar to probe tip 310 as taught in
Bi-polar probe 371 discloses conical shaped electrode 301 and tip 351 for minimally invasive single point entry. Probe diameter 358 is similar to a 20-gage or other small gauge syringe needle, but may be larger or smaller depending on the application, surface area required and depth of penetration necessary. In disclosed embodiment, electrode shaft 302 is 30 mm long with approximately 5 mm not insulated. Lengths and surface areas of both may be modified to meet various applications such as in cosmetic surgery or in elimination of back pain. The conductive return electrode 302 is fabricated from medical grade stainless steel, titanium or other conductive material. The dielectric insulator 305 in the disclosed embodiment is a transparent medical grade material such as polycarbonate, which may double as a light pipe or fiber optic cable. The high intensity light source 408 LED/laser (
The hollow chisel electrode 352 is often used as a syringe to deliver medication such as local anesthetic, medications,/tracer dye. The hollow electrode may also extract a sample. Dielectric insulator 305 in the disclosed embodiment is a transparent medical grade polycarbonate and performs as a light pipe or fiber optic cable. The novel dual-purpose dielectric reduces probe diameter and manufacturing costs. Light source 408, typically a LED or laser (
The bi-polar probe 373 discloses a tapered conical shaped probe for minimally invasive single point entry. It is constructed similarly to probe 371 as taught in
Description of this probe is described in both drawings 2A and 3D. Bi-polar probe 374 (not drawn to scale) consists of insulating dielectric body 309 made from a suitable biologically inert material, such as Teflon, that covers split return electrodes 302 and 303. Conductive return electrodes 302 are fabricated from medical grade stainless steel, titanium or other suitable conductive material. Hollow or solid split conductive tip electrodes 301 and 311 protrude from surrounding dielectric insulator 305. Their operation is very similar to probe tip 380 as taught in
Probe handle (not drawn to scale) encloses memory module 331, on/off switch 310 and mode switch 367. Temperature sensor 330 (located close to tip) monitors tissue temperature. Split electrode 380 (
Connections consist of a tapered dielectric sleeve 309 covering the ridged stainless electrode tube 302. Insulating sleeve 309 is made from a suitable biologically inert material, which covers electrode 302. Dielectric 305 insulates conical tipped electrodes 351 and 301.
Ablation probe 371 is inserted and directed anatomically into the area where the target nerve to be ablated (Box 531) is located. Test current 811 is applied (Box 532). If probe is located in the immediate proximity of the target nerve a physiological reaction will be detected/observed (Example: During elimination of glabellar furrowing, muscle stimulation of the forehead will be observed). If reaction is observed, then a mark may optionally be applied on the surface of the skin to locate the area of the nerve. Power is applied (Box 535) in an attempt to ablate the nerve. If physiological reaction is not observed, (Box 534) the probe will be relocated closer to the target nerve and the stimulation test will be repeated (Box 536 & 537). If no physiological reaction is observed, the procedure may be terminated (Box 544). Also, the probe may be moved in any direction, up, down, near, far, circular, in a pattern, etc. to create a larger area of ablation for a more permanent result.
In Box 537, if stimulation is observed again, then the ablation power may be set higher (Box 538), alternatively, as mentioned, the needle may be moved in various directions, or a larger dosage of energy may be reapplied, to form a larger area of ablation for more effective or permanent termination of signal conduction through the nerve. After delivery of power (Box 540), stimulation energy may be applied again (Box 541). If there is no stimulation, the procedure is completed (Box 544). If there is still signal flow through the nerve (stimulation or physiological reaction) then the probe may be relocated (Box 542) and the procedure is started over again (Box 533).
Auxiliary probes 771 and 772 (
Operation 530 (
Between each ablation, procedure 540 (
As an example and not a limitation, five ablation regions (140, 141, 142, 143, and 144) are shown in
Probe insertion and placement is same as taught in
In special cases were target nerve 101 or ablation region 640 is in close proximity to second nerve 111 or skin 330 bi-polar probes 371 or 372 (
Probe construction is similar to
This probe may be used in conjunction with any of the therapeutic probes 371 and their derivatives. The needle itself will be very fine in nature, such as an acupuncture type needle. By its small size, numerous needle insertions may be accomplished with no scarring and minimal pain. The probe 771 will be inserted in the vicinity of the target tissue through skin 330. The exposed tip of 771, 702 will be exposed and electrically connected to generator 732 via wire 734. The surface of probe 771 is covered with dielectric 704 so the only exposed electrical contact is surface 702 and return electrode 736. Exposed tip 702 will be advanced to the vicinity of target 101 and test stimulation current will be applied. Appropriate physiological reaction will be observed and when the tip 702 is properly located, depth will be noted via observing marks 765. External mark 755 may be applied for reference. Ablation probe 371 may then be advanced to the proximity of the target tissue under the X mark 755 and ablation/nerve destruction as described elsewhere may be performed.
Dual tipped probe 772 offers an additional embodiment that eliminates return electrode pad 736. Probe frame/handle 739 holds two fine needles, 702 and 701, in the disclosed embodiment that are spaced a short distance (a few mm)-mm apart (730). The shaft of conductive needle 701 is covered with dielectric insulator 706, similar to the construction of probe 771 (
Probes 702 and 701 are very small gage needles similar in size to common acupuncture needles, thus permitting repeated probing with minimal discomfort, bleeding, and insertion force. Sharp probes are inserted thru skin 330 and muscle layer(s) 710 near nerve 101. The practitioner locates target nerve 101, then the skin surface may be marked 755 as location aide for ablation step as shown in flow chart (
Auxiliary probes 771 and 772 (
Auxiliary probe 771 and 772 provide a method to quickly locate shallow or deep target structures. Shallow structures are typically marked with ink pen allowing illuminated ablation probe 371 or its equivalents to be quickly guided to mark 755. Optionally, non-illuminated probes may be used by the practitioner who simply feels for the probe tip. For deep structures, probe 771 may also be employed as an electronic beacon; small current 811 (which will be lower intensity and different from the stimulating current) from probe tip 702 is used to guide ablation probe 372. Amplifier 430 (
Lower energy pulse width modulated (or PWM) sinusoid 920 for coagulation is also well known to electro-surgery art. Variations of cut followed by coagulation are also well known.
Auxiliary probes 771 and 772 (
Ablation probe 372 is inserted thru skin 330 and muscle layer(s) 710 near nerve 101. Illumination source 408 permits practitioner to quickly and accuracy guide illuminated 448 ablation probe 372 into position. Illumination 448 from ablation probe as seen by practitioner 775 is used as an additional aide in depth estimation. Selectable nerve simulation current 811 aids nerve 101 location within region 1204. This novel probe placement system gives practitioner confidence system is working correctly so s/he can concentrate on the delicate procedure. Accurate probe location permits use of minimal energy during ablation, minimizing damage to non-target structures and reducing healing time and patient discomfort.
Region 1203 shows the general shape of the ablation region for conical tip 301. Tip 301 is positioned in close proximity to target nerve 101. Ablation generally requires one or a series of localized ablations. Number and ablation intensity/energy are set by the particular procedure and the desired permanence.
Five ablation regions are illustrated 140, 141, 142, 143, and 144; however, there could be more or less regions. Ablation starts with area 144, then the probe is moved to 143 and so on to 140, conversely, ablations could start at 140 and progress to 144. Also, the practitioner could perform rotating motions, thus further increasing the areas of ablation and permanence of the procedure. Between each ablation procedure 540 (
Controller 101 maintains local probe 1460, patient 1430, and procedure 1410 databases. All work together to insure correct probes and settings are used for the desired procedure. Automatically verifying that the attached probe matches selected procedure and verifying probe authentication and usage to avoid patient cross contamination or use of unauthorized probes. Automatic probe inventory control quickly and accurately transfers procedure results to the billing system.
From a touch screen, the practitioner selects the desired procedure from list 1410. For example “TEMPORARY NERVE CONDUCTION” 1411, “SMALL TUMOR 1CC” 1412, and “SMALL NERVE ABLATE” 1413 are a few of the choices. Each procedure has a unique procedure code 1416 to be used in the billing system. Power range parameter 1417 is a recommended power setting via power level control 404. The recommended probe(s) Associated with procedure 1415 and power range parameter 1417 are listed in parameters 1419. With the probe connected, the part number is read from memory 331 (
From touch screen 450 (
During the procedure (
Use of a USB memory stick permits continued operation in the event of a network 1326 failure Data is loaded to memory 1338 for simple transfer to office computer 1306 (
If computer network 1326 such as Ethernet 802.11 or wireless 802.11x is available, files are mirrored to local storage 1309, remote server 1307. The remote server (typically maintained by equipment manufacture) can be remotely update procedure(s). To insure data integrity and system reliability a high availability database engine made by Birdstep of Americas Birdstep technology, Inc 2101 Fourth Ave. Suite 2000, Seattle Wash. is offered as an example. The Birdstep database supports distributed backups, extensive fault and error recovery while requiring minimal system resources.
From a touch screen, the practitioner selects or enters patient name from previous procedure 1430 and creates a new record 1433. Similarly, a procedure is selected from 1410 (for example “TEMPORARY NERVE CONDUCTION” 1411, “SMALL TUMOR 1CC” 1412, and “SMALL NERVE ABLATE” 1413). Each procedure has a unique procedure code 1416 that is used for the billing system. Other information such as practitioners name 1440, date 1435 is entered to record 1433. As taught above probe appropriate for the procedure is connected and verified, part 1470 and serial number 1469 recorded.
The practitioner enters additional text notes to file 1442 or records them with microphone 455 (
At the end of procedure, records are updated and stored to memory 438. Backup copies are written to USB 1320 memory stick 1338 (
Alternative Probe Configurations
In an equal electrode surface area implementation, one of the conductive electrodes 2002, 2004 may be selectively connected to a stimulation current source or an ablation current source as described above. The other electrode 2002, 2004 may be unconnected or connected as a ground or return path for the connected current source. In the embodiment shown in
Since electrodes 2002 and 2004 have substantially equal surface area, the local heating formed upon the application of RF ablation energy to the active electrode 2002 results in a heating zone having a substantially symmetrical ellipsoid form.
The single axis electrosurgical probe 2000 of
The probe 2000 of
The probe 2000 of
Placement Methods
Several methods of properly positioning a probe adjacent to a selected nerve for ablation energy application are discussed above. For example, probe placement methods featuring florescence marker dyes, optical probe guidance and electronic probe guidance with the use of low energy nerve stimulation current are discussed in detail. Certain of the alternative probe configurations as illustrated in
The single axis electrosurgical probe 2000 of
For example, the
In probe embodiments where the stimulation electrode is positioned in between the ablation electrodes 2030, 2032, the above described iterative method guarantees that the target nerve is positioned within an elliptical ablation zone 2064 (see
The multiple electrodes of the
For example, with reference to
Sequentially, the stimulation current is then applied between electrodes 2050 and 2052 with similar strong muscle response observed. This sequential stimulation and response process is observed through the activation of electrodes 2056 and 2058 where the muscle response is substantially diminished or not observable. This is an indication that electrodes 2048 through 2056 are all in contact with the nerve 2042. The electrodes 2048 through 2056 may then be switched to the ablation current source activated and sequentially or simultaneously in bi-polar pairs or individually in bi-polar or mono-polar mode to ablate the nerve 2042. The nerve could be ablated along a select length defined by the number of electrodes activated by the practitioner. This method could also be implemented in mono-polar mode whereby stimulation or ablation energy is applied between one or more electrodes 2046 through 2062 and a separate return electrode applied externally on the body.
The above methods of angular probe positioning and sequential stimulation may be combined with the iterative techniques also described above. For example, the stimulation current generator may be set at a relatively high level initially and reduced when the general location of the nerve with respect to certain electrodes is determined.
For example, the stimulation current threshold (to elicit an observable response) between electrodes 2048 and 2050 of
While the invention has been particularly shown and described with reference to a number of embodiments, it would be understood by those skilled in the art that changes in the form and details may be made to the various embodiments disclosed herein without departing from the spirit and scope of the invention and that the various embodiments disclosed herein are not intended to act as limitations on the scope of the claims.
Claims
1. An electrosurgical probe comprising:
- a probe body defining a longitudinal probe axis; and
- a first and a second conductive electrode operatively disposed along the probe axis wherein the surface area of the first conductive electrode is substantially greater than the surface area of the second conductive electrode.
2. The electrosurgical probe of claim 1 wherein a ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode is equal to or greater than 3:1.
3. The electrosurgical probe of claim 1 wherein a ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode is equal to or greater than 8:1.
4. The electrosurgical probe of claim 1, wherein a ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode is adjustable.
5. The electrosurgical probe of claim 1 further comprising a stimulation energy source in electrical communication with at least one of the first or second conductive electrodes.
6. The electrosurgical probe of claim 5 further comprising an ablation energy source in electrical communication with at least one of the first or second conductive electrodes.
7. The electrosurgical probe of claim 6 further comprising a switch providing for the selective connection of the stimulation energy source or the ablation energy source to at least one of the conductive electrodes.
8. An electrosurgical probe comprising:
- a probe body defining a longitudinal probe axis;
- an active electrode operatively associated with the probe body at a first location along the probe axis;
- a stimulation electrode operatively associated with the probe body at a second location along the probe axis; and
- a return electrode operatively associated with the probe body at a third location along the probe axis.
9. The electrosurgical probe of claim 8 wherein the stimulation electrode is positioned along the probe axis between the active electrode and the return electrode.
10. The electrosurgical probe of claim 8 further comprising a stimulation energy source in electrical communication with the stimulation electrode.
11. The electrosurgical probe of claim 10 wherein the stimulation energy source provides variable stimulation current.
12. The electrosurgical probe of claim 10 wherein at least one of the active electrode and the return electrode is in electrical communication with a ground for the stimulation energy source.
13. The electrosurgical probe of claim 10 wherein both of the active electrode and the return electrode are in electrical communication with a ground for the stimulation energy source.
14. The electrosurgical probe of claim 7 further comprising an ablation energy source in electrical communication with the active electrode.
15. The electrosurgical probe of claim 13 wherein the ablation energy source provides variable ablation energy.
16. The electrosurgical probe of claim 15 wherein the ablation energy source provides energy which has at least one of variable voltage, current and waveform.
17. An electrosurgical probe comprising:
- a probe body defining a longitudinal probe axis;
- at least three electrodes operatively associated with the probe body at separate locations along the probe axis; and
- a stimulation energy source in electrical communication with at least one of the electrodes.
18. The electrosurgical probe of claim 17 wherein the stimulation energy source provides variable stimulation energy.
19. The electrosurgical probe of claim 17 wherein the stimulation energy source may be selectively connected to at least one or more of the electrodes.
20. The electrosurgical probe of claim 17 further comprising a stimulation energy ground in electrical communication with the stimulation energy source, wherein the stimulation energy ground may be selectively connected to at least one or more of the electrodes.
21. The electrosurgical probe of claim 17 further comprising an ablation energy source in electrical communication with at least one of the electrodes.
22. The electrosurgical probe of claim 21 wherein the ablation energy source provides variable ablation energy.
23. The electrosurgical probe of claim 22 wherein the ablation energy source provides energy which has at least one of variable voltage, current and waveform.
24. The electrosurgical probe of claim 21 wherein the ablation current source may be selectively connected to at least one or more of the electrodes.
25. The electrosurgical probe of claim 21 further comprising an ablation energy ground for the ablation energy source, wherein the ablation energy ground may be selectively connected to one or more of the electrodes.
26. A method of positioning an electrosurgical probe comprising:
- providing an electrosurgical probe having a probe body defining a longitudinal probe axis, multiple conductive electrodes operatively disposed along the probe axis, and a stimulation energy source in electrical communication with at least one of the conductive electrodes;
- inserting the electrosurgical probe to a first position within tissue containing a target nerve;
- applying first stimulation energy to the stimulation electrode;
- observing a first response of a muscle associated with the target nerve;
- moving the electrosurgical probe to a second position within the tissue containing the target nerve;
- applying second stimulation energy to the stimulation electrode; observing a second response of a muscle associated with the target nerve; and
- comparing the second response of the muscle associated with the target nerve to the first response of the muscle associated with the target nerve.
27. The method of claim 26 further comprising:
- providing a variable stimulation energy source; and
- varying the stimulation energy between the first and the second applications of stimulation energy.
28. A method of positioning an electrosurgical probe comprising:
- providing an electrosurgical probe having a probe body defining a longitudinal probe axis, multiple conductive electrodes operatively disposed along the probe axis, and a stimulation energy source which may be connected sequentially to more than one of the conductive electrodes;
- inserting the electrosurgical probe into tissue containing a target nerve;
- applying stimulation current to a select first electrode;
- observing a first response of a muscle associated with the target nerve; applying stimulation energy to a select second electrode;
- observing a second response of the muscle associated with the target nerve; and
- comparing the second response of the muscle associated with the target nerve to the first response of the muscle associated with the target nerve.
29. The method of claim 28 further comprising:
- applying stimulation energy to a select third electrode; observing a third response of the muscle associated with the target nerve; and
- comparing the third response of the muscle associated with the target nerve to the second response of the muscle associated with the target nerve.
30. The method of claim 29 further comprising sequentially applying stimulation energy to the first, second and third electrodes.
Type: Application
Filed: Jul 28, 2006
Publication Date: Mar 15, 2007
Applicant: JNJ Technology Holdings LLC (Parker, CO)
Inventors: William Janssen (Parker, CO), James Newman (San Mateo, CA), Ammon Balaster (Boulder, CO), Jeffrey Buske (Broomfield, CO)
Application Number: 11/460,870
International Classification: A61B 18/04 (20060101); A61B 5/05 (20060101);