Abstract:
A unipolar electrosurgical electrode or probe that is configured for use in MIS electrosurgical procedures. The electrosurgical electrode comprises a long, thin, flexible, insulated wire configured to cooperate with the small cannula of a mini-endoscope to reach interior tissue not normally reachable by electrosurgical electrodes. When energized, a unipolar discharge is generated at the working end of the electrode. The probe can be used for spinal and endonasal procedures.

Description:
RELATED APPLICATION 
     This application is a CONTINUATION-IN-PART of a commonly owned patent application Ser. No. 10/742,031, filed in the U.S. Patent And Trademark Office on Dec. 22, 2003, now abandoned, and entitled FLEXIBLE ELECTROSURGICAL ELECTRODE FOR TREATING TISSUE 
    
    
     This invention relates to an electrosurgical probe for treating ailments or diseases by minimally invasive surgery (MIS) or similar procedures. 
     BACKGROUND OF THE INVENTION 
     Our prior patent, U.S. Pat. No. 5,505,728, whose contents are incorporated herein by reference, describes a novel electrosurgical electrode for ablating or shrinking throat tissue in a surgical procedure. This is accomplished by an electrosurgical electrode activated by electrosurgical currents that is applied by the surgeon to the patient. 
     Our prior patent, U.S. Pat. No. 6,447,510, whose contents are incorporated herein by reference, describes a novel electrosurgical electrode for the treatment of benign and malignant lesions of the upper aerodigestive tract. This is accomplished by an electrosurgical electrode activated by electrosurgical currents and configured such that it can be applied by the surgeon to the patient via the rigid cannula of a laryngo-pharyngoscope. The electrode is stiff and specifically configured for this particular procedure. 
     There is a need in the art for devices to simplify the treatment by MIS of other tissues which cannot be reached by the electrodes described in the referenced patents. These include, among others, epidural scar tissue, adhesions and other pathology, spinal diseases such as intradiscal shrinkage or ablation, endoscopic endonasal procedures, as well as treating internal tissues reachable only by, for example, being snaked or threaded up into a vein to travel up to leg lesions, etc. 
     Laser have been used for some of such purposes in a MIS procedure but has disadvantages, which include, but are not limited to: the radiation can be dangerously reflected by shiny reflecting metallic surfaces, requiring the use of non-reflective working channel scopes, and limiting the use of reflecting instruments; laser beam scatter may cause skin burns, fire or the generation of toxic products; problems may arise if the laser beam impinges on the cannula or other equipment; safety measures are necessary such as warning lights, safety glasses, and laser safety courses are required. 
     SUMMARY OF THE INVENTION 
     An object of the invention is an improved electrosurgical probe for treating tissue. 
     Another object of the invention is an improved electrosurgical probe for treating tissue that can use a standard operating room working channel fiberoptic scope or endoscope. 
     Still another object of the invention is an improved electrosurgical probe that can be used with flexible steerable endoscopes. 
     Still another object of the invention is an improved electrosurgical probe for treating tissue that has in the past been reachable and treatable only through the use of laser radiation. 
     In accordance with a feature of the invention, an electrosurgical probe comprises a very long, thin, flexible, insulated, monopolar wire electrode, so thin and flexible that it can be used with a miniature or micro-sized endoscope combining imaging optics and an instrument channel with an overall diameter below about 3 mm. It is also sufficiently thin and flexible, but also stiff enough, that it can be used with flexible steerable endoscopes and in addition can be snaked down or threaded up into a vein to reach leg lesions. Because of its capability of use with a miniature or micro-sized endoscope in a standard operating environment, hospital or office, it allows a surgeon to conduct a procedure with improved visualization of the surgical site. With the preferred dimensions given below, a 600 mm electrode can easily be coiled without breaking to form a 3-turn loop with a diameter as little as 2–3 inches. 
     In a preferred embodiment, the elongated probe comprises at its proximal end a novel connector, connected by cable to a standard electrosurgical apparatus or its equivalent, and that can be made sterile and thus operable by the surgeon with fingers of only one hand, allowing the surgeon to remove the electrosurgical probe of the invention and attach another electrode to perform another function at the same surgical site all while maintaining a sterile field at the patient&#39;s side. 
     In another preferred embodiment, the elongated probe comprises at its distal end an exposed blunt wire end. 
     In still another preferred embodiment, the elongated probe comprises at its distal end an exposed shaped member connected to a wire end. Preferably, the shaped member has in front an American football shape or a bullet shape, which is especially useful for endonasal procedures. 
     Preferably, the overall outside diameter of the electrosurgical electrode of the invention is 1 mm or less, and it has an overall length, measured from the connector, of at least about 475 mm, preferably, about 600 mm for certain procedures, especially spinal procedures, but for treating endonasal tissues that can be reached with a shorter electrode a length of at least about 150 mm is preferred. A longer length of at least about 280 mm is generally preferred for most procedures. For such procedures, a maximum diameter of about 0.06 mm can be used. 
     By “proximal” is meant the end closest to the connector, and by “distal” is meant the end furthest from the connector. 
     The construction of the invention will provide important benefits for all MIS arthroscopic or endoscopic procedures and in many cases enables the efficient delivery of radiofrequency (RF) energy technology for controlled precise tissue cutting, absorption and other tissue effects and in a safe manner. It is cost effective and considerably less expensive than other surgical modalities such as lasers where the novel electrode configuration may be of importance, as well as for general electrosurgical procedures where the volumetric reduction of tissue or ablation of tissue that is hard to reach with the known electrodes is desirable. Examples of particular procedures for which the electrosurgical electrode of the invention is particularly suitable is spinal disc reduction and endonasal procedures. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described the preferred embodiments of the invention, like reference numerals designating the same or similar elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a schematic view of one form of an electrosurgical probe according to the invention shown coiled to emphasize its flexibility and also connected to electrosurgical apparatus; 
         FIG. 2  is a side and partially cross-sectional view of the straightened electrosurgical probe shown in  FIG. 1  with its attached connector; 
         FIG. 3  is an enlarged cross-sectional view of the working end of the probe of  FIG. 2 ; 
         FIG. 4  is an enlarged cross-sectional view of the working end of the probe to which a football-shaped member has been attached; 
         FIG. 5  is an end view of the working end of the probe of  FIG. 4 ; 
         FIG. 6  is an enlarged side view of the working end of the probe to which a bullet-shaped member has been attached; 
         FIG. 7  is a perspective view of the working end of the probe of  FIG. 6 ; 
         FIG. 8  is an enlarged side view of the working end of the probe to which another shaped member has been attached; 
         FIG. 9  is a schematic view illustrating one possible procedural use of an electrosurgical electrode according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The reader is directed to the referenced prior patents for a more detailed description of electrosurgical procedures and principles of operation which will assist in understanding the invention described in the present application. 
     In the present application,  FIG. 1  is a generally schematic view of one form of electrosurgical electrode  10  in accordance with the invention shown connected by way of engagable connectors  12 ,  14  and a cable  16  to a conventional electrosurgical apparatus  18 .  FIG. 2  shows just the electrode part with in this case a female connector  12 . 
     The connector  12  construction is a hollow insulating member made of an autoclavable plastic with outer grooves or knurls  20  for easy manipulation by the fingers of a user, and containing at its right end a reduced diameter section  22 . Inside a bore  24  extends a hollow metal, e.g., of brass, female receptacle  26  which is fully surrounded by the insulating section  22 , and is actually recessed  27  a short distance to prevent accidental contact with the user. The female receptacle  26  narrows down to a thin tube  28  into which is mounted the bare end of a metal wire  30  thereby forming a good electrical connection between the metal receptacle  26  and the wire  30 . The connection between the latter can be for example by welding or brazing. Except for that welded or brazed connection, the remainder of the wire  30  is surrounded by a thin insulating coating or sheath  32  of a flexible autoclavable plastic such as Teflon. The entire length of the wire  30  is sheathed in this insulating sheath  32  except for a small section  34  at the distal end of the wire which is left bare and electrically exposed. That bare end  34 , shown enlarged in  FIG. 3 , is the working end of this form of the electrode. The female connector  12  is permanently attached to the wire  30 . The wire  30  is preferably made of tungsten though other electrically conductive metals that when thin are flexible can be used such as stainless steel and brass. The exposed bare end  34  is equal to or less than about 1 mm, and can be as small as 0.125 mm. The coating adds only about 0.15 mm. For certain procedures, the end  35  should be blunt so it will more easily pass through a cannula, especially a bent cannula. 
     For its intended use, the elongated electrode  10  comprises a thin highly flexible insulated wire that is sufficiently thin and flexible, but sufficiently stiff, that it can be used with a flexible steerable endoscope or a miniature micro endoscope and in addition can be snaked down or threaded up into a vein to reach, e.g., leg lesions. It has sufficient resilience that, if bent, it will spring back to its initial position. For these applications, the overall diameter of the sheathed wire must be about 1 mm or less, and it must have an overall length, measured from the connector  12 , of at least about 475 mm, preferably, about 600 mm. Thus, a miniature micro endoscope whose channel is typically less than about 3 mm can accommodate the wire, and its flexibility allows it to be used with flexible steerable endoscopes, flexible cannulas, and flexible scopes to access areas of the body internally. Its very long length enables the working end  34  to reach tissue at body locations that heretofore were only reachable by means of a laser fiber or traditional surgery. 
     One form of the electrode of the invention is especially important for spinal surgery, for example, targeted treatment of epidural scar tissue, adhesions and other pathology, or for precise intradiscal shrinkage or ablation. Combined with a miniature micro endoscope, in turn combining imaging optics and an instrument channel with an overall diameter below 3 mm, access and visualization of the epidural space is now a viable option. 
     A further advantage is obtained when the electrode of the invention is used with electrosurgical apparatus capable of generating RF electrosurgical currents at frequencies of about 4 MHz. The monopolar electrode wire thus enables the efficient delivery of RF energy and is uniquely suited for spinal procedures, such as myeioscopy or endoscopic epiduraplasty, due to the controlled precise tissue absorption and versatile tissue effects and safety it affords. The resultant technology is cost effective and considerably less expensive then other surgical modalities such as lasers, and offers the further advantage that it delivers lower tissue temperature profiles. Moreover, it allows more easily the extension of RF electrosurgical currents to minimal and micro invasive surgical procedures. Minimal and micro surgical procedures typically result in reduced pain and scarring, shorter recovery time and increased effectiveness compared to traditional surgical procedures. Most of the pain associated with traditional surgery procedures results from the cutting of layers of skin and muscle tissue, which also delays healing and generates high levels of pain. An example of suitable electrosurgical apparatus is the Model SURGITRON Dual-Frequency electrosurgical unit manufactured by and available from Ellman International, Inc. of Oceanside, N.Y. 
     As indicated in  FIG. 1 , the female connector  12  is connectable to its male counterpart  14 , which comprises also a hollow insulating member  39  made of an autoclavable plastic with outer grooves or knurls  40  and contains on a bore  42  inside a recessed electrically conductive male plug  44  which is internally connected to the cable  16  that can be plugged into the electrosurgical apparatus  18 . The configuration is such that when the two connectors  12 ,  14  are engaged, the male contact  44  will engage the female receptacle  26  whereupon the cable  16  is connected to the wire electrode  30 . The overall length of the engaged connectors is about 60–80 mm, each being about one-half the length. The direct connection of the wire electrode to the novel connector  12 , which is a departure from traditional electrosurgery electrode handpieces, has the important advantage that the engaged connectors  12 ,  14  can function as a finger connector and is simply maneuvered and manipulated with the fingertips of the user, typically the index finger and thumb fingertips. Since the entire electrode  10  with its attached connector as well as the connector  14  are autoclavable, i.e., sterilizable, while maintaining the sterile field at the patient&#39;s site, the surgeon when desired can with one hand disconnect or connect the sterile connectors  12 ,  14  and reconnect to the free female connector  12  another electrode, say for a different cutting, shrinking or coagulating function. 
     It will also be appreciated that the arrangement of the male and female parts of the connectors can be reversed, but in the manner illustrated certain standard practices are followed allowing other male oriented connectors to be connected to the female connector  12 . 
     While the blunt wire end  35  illustrated is the most versatile, it may be desirable to provide a small ball at the distal end for easier threading through a vein. 
     A further important application for the electrosurgical electrode of the invention is in the treatment more specifically for endoscopic endonasal surgery with RF electrosurgical currents, preferably at about 34 MHz. In the past, such sinus and nasal procedures could be done only with a laser fiber. The electrosurgical electrode of the invention can easily accomplish the same ablative, vaporizing, and debulking of diseased tissue within the nasal cavity, but with the benefits described above. For such applications, we prefer a sheathed fiber that that comprises an insulatingly coated thin wire of less than about 1 mm in diameter, provided with a generally American football-shaped electrically-conductive member affixed to the end of the wire to form the active end. The football shape allows the operating surgeon to traverse or sweep the tissue area to be treated with the smooth sides of the active end which may be desirable for ablative, vaporizing, and debulking of diseased tissue. A bullet shape, simulating one-half of a football may also be suitable. 
       FIGS. 4 and 8  illustrate, respectively, active ends having football and bullet shapes. In  FIG. 4 , the sheathed conductive fiber is indicated by  40 , and the attached exposed football-shaped end is indicated by  42 . The football shape, which in its forward section in cross-section resembles an ellipse, is preferred because of its smooth sides all around and the tapered un-pointed distal end  44  which makes the electrode easier to move around in the nasal tissue and provides good visualization of the active tissue site. The OD of the ellipse at its maximum diameter  46  is preferably about 0.5–0.75 mm. One-half of the major axis of the ellipse is preferably about 1–1.5 mm. Its overall length is preferably about 2–4 mm. It may be attached to the wire end by, for example, solder or an electrically-conductive adhesive. The bullet shape  50  illustrated in  FIGS. 6 and 7  has a similar front end configuration and will also prove acceptable for many procedures.  FIG. 8  shows another useful shape with similar properties. 
       FIG. 9  illustrates schematically the electrode of the invention of  FIG. 4  present in the sinus region of a patient via an endonasal scope. The view shown is the endoscopic depiction of the endonasal electrode of the invention with the football tip resecting the septal spur. This procedure previously could only be accomplished with a laser, with the possible disadvantages that the laser can produce a high degree of char and there may be delayed healing and post operative complications as a result. The RF electrosurgical electrode of the invention preserves the tissue and will enhance the healing process. Endoscopes that can be used are available commercially and such endoscopes and such types of procedures using lasers are described at length in “Functional Endoscopic Endonasal Surgery”, by Hopf and Hopf, published 2001 by Endo-Press of Tuttlingen, Germany, summarized at Pgs. 6–8. 
     In this description, by “elongated” or “longitudinal” is meant parallel to the long axis of the electrode (horizontal in  FIG. 2 ). 
     Once the surgeon has positioned the working end  34  of the electrode with respect to the tissue to be operated on, he or she then activates the electrosurgical apparatus  18  causing a discharge of unipolar currents between a ground plate (not shown) and the bare electrode end  34  capable of causing excision or ablation or shrinkage of tissue or cauterization of a blood vessel in the usual way. As with the embodiments of the prior patents, the insulating coating on the electrode  10  will prevent accidental touching of any conductive members or patient tissue by the electrode sides, so that the unipolar discharge is localized to the region surrounding the working end  34 . 
     While the invention has been described in connection with preferred embodiments, it will be understood that modifications thereof within the principles outlined above will be evident to those skilled in the art and thus the invention is not limited to the preferred embodiments but is intended to encompass such modifications.