Abstract:
A unipolar electrosurgical instrument that is configured for use in MIS and other electrosurgical procedures, primarily for the treatment of benign and malignant lesions of the upper aerodigestive tract. The instrument is configured to cooperate with the cannula of a laryngo-pharyngoscopes. The shape includes a short proximal section at an angle to a long middle section which leads to an offset working end containing a unipolar electrode. When energized, a unipolar discharge is generated at the working end of the electrode.

Description:
This invention relates to a microlarynx electrosurgical probe for treating ailments or diseases of the larynx. 
     BACKGROUND OF THE INVENTION 
     Our prior U.S. Pat. No. 5,505,728, whose contents are incorporated herein by reference, describes a novel electrosurgical electrode for ablating or shrinking palatopharynx 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. 
     There is a need in the art for devices to simplify the treatment of benign and malignant lesions of the upper aerodigestive tract. These include, among others, lesions, laryngomalacia,-cysts, laryngocele, hemangioma, stenosis, nodules, polyps, tumors, etc. 
     Laser have been used for such purposes in a minimally invasive surgery (MIS) procedure but has disadvantages, which include, but are not limited to: the radiation can be dangerously reflected by shiny metallic surfaces, requiring the use of non-reflective laryngo-pharyngoscopes made of special plastic which are expensive instead of the standard stainless steel laryngo-pharyngoscopes, 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 endotracheal tube; 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 microlarynx electrosurgical probe for treating tissue. 
     Another object of the invention is an improved microlarynx electrosurgical probe for treating tissue that can use a standard operating room laryngo-pharyngoscope. 
     Still another object of the invention is an improved microlarynx electrosurgical probe for treating tissue that avoids the use of laser radiation. 
     In accordance with a feature of the invention, a microlarynx electrosurgical probe comprises an elongated shaft configured such that it can be fitted down a standard operating room laryngo-pharyngoscope and allows the surgeon to conduct the procedure with improved visualization of the surgical site. 
     In a preferred embodiment, the elongated probe comprises at its proximal end a bare shank for fitting into a standard electrosurgical handpiece or its equivalent, and at its distal end an offset section leading to the active electrode, which may be, for example, a conventional ball, wire, needle, or loop. By “proximal” is meant the end closest to the handpiece, and by “distal” is meant the end furthest from the handpiece. 
     The construction of the invention will provide the same important benefits not only for MIS of lesions of the upper aerodigestive tract but also for other MIS arthroscopic procedures 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 is desirable. 
     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 a microlarynx electrosurgical probe according to the invention mounted in a handle or handpiece connected to electrosurgical apparatus; 
     FIGS. 2,  3 , and  4  are, respectively, side and perspective views of one form of microlarynx electrosurgical probe according to the invention but with different active electrodes; 
     FIG. 5 is a schematic view of the probe of FIG. 2 shown in use with a patient. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The reader is directed to the referenced prior patent 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 side view of one form of electrosurgical instrument  10  in accordance with the invention. It comprises a handle  12  with a conventional front end  14  adapted to receive and hold rigidly the shank end (not shown in FIG. 1) of an elongated electrode or probe  16  whose working end  18  is shown at the distal end. The handle  12  is typically electrically-insulating or if conductive covered with an electrically-insulating coating. Similarly, the entire electrode elongated shaft  20  except for the bare shank end, is also coated with an electrically-insulating coating, leaving bare the active electrode  24  at the working end  18 . The shaft  20  is long enough to extend through the trocar or channel of a standard stainless steel laryngo-pharyngoscope so that its working end  18  is exposed inside the patient&#39;s throat. At the left end of the handle  12  is shown a cable  26  which contains wires for receiving unipolar electrosurgical currents from a conventional electrosurgical apparatus  28 . The electrosurgical apparatus preferably is an ultra high frequency (RF) radiosurgical energy source, which operates in the range of about 3.8-4.0 MHz. Studies have shown that the 3.8-4.0 MHz frequency range is the preferred RF energy to incise and coagulate tissue because tissue thermal necrosis is minimal and, when interfaced with the electrosurgical electrode of the invention, provides excellent cutting and hemostasis especially for throat procedures. An example of suitable electrosurgical apparatus is the Model SURGITRON Dual-Frequency electrosurgical unit manufactured by and available from Ellman International, Inc. of Hewlett, N.Y. 
     FIGS. 2-4 illustrate three embodiments of the invention which differ only in the shape of the active electrode end. In FIG. 2 the active end is a needle or pointed wire  30 . In FIG. 3 the active end is a ball  32 . In FIG. 3 the active end is a loop  24 , also as shown in FIG.  1 . 
     The shape or configuration of the electrode  16  is significant. As will be observed, the shank  36  at the left or proximal end is bare and extends into a first electrically-insulated section  38 —which is about 1 inch long, referenced  72 , preferably about 0.75-1.25 inches long—that extends at an angle  40  of about 45°, preferably about 40-50°, with respect to the longitudinal or long axis  42  of the adjacent second electrically-insulated section  44 ,—which is about 8.75 inches long, referenced  74  preferably about 8-9.25 inches long—. The second section  44  terminates in a thinner third section  46 —which is about 0.25 inches long, referenced  80 , preferably about 0.1-0.33 inches long—, axially aligned with the axis  42 , which leads into a fourth section  48 —which is about 0.125 inches long, referenced  82 , preferably about 0.1-0.3 inches long—that is offset at an angle  50  of about 155°, referenced  50 , preferably about 145-165° but angles in the opposite direction from that of the first section  38 . The whole electrode is in the same plane, that of the drawing. So, where the first section  38  extends downward from the axis  42 , then the fourth section  48  extends upward away from the axis  42 . After a short distance, the fourth section  48  leads into a fifth section  52 —which is about 0.125 inches long, referenced  84 , preferably about 0.1-0.3 inches long—which extends approximately parallel to the axis  42  and finally leads into the active electrode end  24 ,  30 ,  32 . The third  46 , fourth  48 , and fifth  52  sections may all remain bare or may be covered if desired, since the ablation action occurs at the active electrode. The overall length, measured parallel to the axis  42  from the beginning or proximal end of the first section  38  to the distal end of the second section  44  is about 9.5 inches or 240 mm, which can vary about 10% in length. The significance of this configuration will be easier to understand from FIG. 5 which illustrates a typical use. 
     A patient  60 , with his mouth  62  open, lies on a table or sits in a chair. The superstructure  63  is used to support a standard laryngo-pharyngoscope  64  which includes a scope and light whose electrical cord  66  is shown. The surgeon  68  is peering through a microscope  70  through which he or she can view the surgical site at the larynx of the patient. His left hand holds the instrument of FIG. 1 by the handle  12 . The cable  26  and electrosurgical apparatus  28  are not shown in this view. The fourth electrode section  44  extends down through a channel (not shown) in the laryngo-pharyngoscope  64  with the active end exposed inside the throat of the patient and available for ablation or coagulation. The surgeon can thus manipulate the handle  12  and thus the active electrode end  24  as desired. The offset fourth section  48  increases the visibility of the active end to the surgeon who is using the scope to view the surgical site and the active electrode while conducting the procedure. The bent first section  38  allows the surgeon to hold the instrument  10  in an approximately horizontal position that he or she is accustomed to with other MIS instruments yet be capable of manipulating the active working end as needed. The overall length allows sufficient tolerance for moving the probe electrode longitudinally as needed for the procedure. 
     In this description, by “axial” is meant parallel to the long axis  42  of the electrode (horizontal in FIGS.  2 - 4 ). By “lateral” is meant transverse to the long axis  42 . “Offset” is intended to include lateral directions as well as acute angles with respect to the long axis  42 . 
     Once the surgeon has positioned the working end  18  of the instrument with respect to the tissue to be operated on, he or she then activates the electrosurgical apparatus  28  causing a discharge of unipolar currents between a ground plate (not shown) and the bare electrode  24 ,  30 ,  32  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 patent, the insulating coatings on the electrode  16  will prevent accidental touching of patient tissue by the electrode sides, so that the unipolar discharge is localized to the region surrounding the working end  24 ,  30 ,  32 . The operation can take place in a dry or wet field. The surgeon positions the electrodes  24 ,  30 ,  32  so as to touch or pass lightly over the tissue to be modulated as needed for the procedure being followed. 
     For example, a suitable metal for the electrodes is brass or stainless steel. A suitable thickness of the electrode  16  is about 0.125 inches. 
     The benefits of the invention include: the use of a standard operating room (OR) laryngo-pharyngoscopes; no laser beam scatter can cause skin bums, fire or the generation of toxic products; the surgeon need not be concerned about a laser beam hitting an endotracheal tube which may ignite and possibly threaten a patient&#39;s life; special laser safety measures are unnecessary such as warning lights, safety glasses, and safety courses; clinically, the thermal alteration from radio frequency energy is less than that of laser energy; radiosurgery with the RF microlaryngeal probe of the invention minimizes thermal damage and penetration is negligible with radio frequency energy. 
     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.