Abstract:
An electrode for laryngeal electromyography that is adhesively secured to an insert device, endotracheal tube or other similar device. The attachable surface electrode of this invention consists of a flexible substrate having an anterior and a posterior surface specifically for insertion along the human laryngopharynx and adjacent to the cricothyroideus muscles (the vocal cords). One or more electrically conductive structures are mounted on or formed on the anterior surface of the substrate to provide an electric contact with the cricothyroideus muscles. Insulated wires extend from the electrical conductive structures for transmitting electrical pulses to the cricothyroideus muscles. There is an adhesive material on the posterior surface of the flexible substrate for attachment to an endotracheal tube, insert device, postcricoid paddle or other such device of the attachable substrate so that the electrically conductive structures thereon are properly positioned for laryngeal electromyography.

Description:
This application is a Divisional of Ser. No. 11/324,484, filed Jan. 3, 2006, now U.S. Pat. No. 7,379,767 issued May 27, 2008. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to electrodes for laryngeal electromyography and in particular to an electrode that is attachable to an insert device of sorts and that is size adjustable to fit the particular application, and in particular for use in pediatrics. 
     During thyroid surgery there is a substantial hazard that the recurrent laryngeal nerve may be severed, stretched or bruised during surgery on, about or near the thyroid gland. The hazard is a result of several factors, including the fact that the recurrent laryngeal nerve lies just posterior to the most inferior portion of the thyroid gland, and is very small and delicate. It can be quite difficult to distinguish this nerve from the background tissue when the area about the thyroid gland is inflamed, as well as covered with blood following the initial incision. As the result, the risk of vocal cord damage or paralysis following thyroid surgery is very high, and also is quite serious in that it can result in the patient&#39;s complete loss of speech. Even if the laryngeal nerve has simply been stretched or bruised, the loss of speech may last for several months. In the unfortunate cases where the nerve is completely severed, the paralysis is permanent, and surgical attempts to repair the same have not yet proven successful. 
     The use of laryngeal electromyography with surface electrodes to locate the recurrent laryngeal nerve has proven successful, as discussed in U.S. Pat. No. 5,178,145 issued to Rea. But the types and sizes of electrodes available are limited. Most electrodes are self retaining in that they have some sort of “built in” means for insertion, such as a paddle or handle. Most electrodes are also fixed in size and may not be adaptable for use on all patients and in particular pediatric patients, small children, and in some cases small adults. 
     SUMMARY OF THE INVENTION 
     In general, the attachable and size adjustable surface electrode for laryngeal electromyography generally consists of a flexible plate having an anterior and a posterior surface specifically for insertion into the human laryngopharynx adjacent to the cricothyroideus muscles (the vocal cords). An electrical conductive plate is mounted on the anterior surface to provide an electric contact with the cricothyroideus muscles. An insulated wire extends from the electrical conductive plate for monitoring or delivering electrical pulses to the cricothyroideus muscles. There are graduations parallel to a center line on the electrical conductive plate for cutting and sizing the flexible plate and electrical conductive plate to the size of the patient&#39;s laryngopharynx. There is an adhesive material on the posterior surface of the flexible plate for attachment of the attachable and size adjustable surface electrode to an endotracheal tube, insert device, postcricoid paddle or other such device. 
     The principal object of the present invention is to provide an electrode and method for laryngeal electromyography to locate a recurrent laryngeal nerve, and in particular an electrode that can be directly attached to an endotracheal tube, insert device, postcricoid paddle or other such device, so it must be flexible and bendable, rather then being self retaining or permanently fixed to some sort of device for insertion. 
     Another object is to provide such an electrode and method for continuous intraoperative laryngeal nerve location monitoring during thyroid surgery. 
     Yet another object is to provide such an electrode and method that is easily attached to an insert device and thus easily inserted in the patient, and in particular small adults, children, and for use in pediatrics, and that is adapted for reliable operation. 
     Another object is to provide such an electrode and method that is simple and accurate in operation whereby surgeons without extensive experience in thyroid surgery may conduct the surgery, yet avoid damage to the laryngeal nerve. 
     Still another object is to provide such an electrode and method to allow monitoring of the cricothyroideus muscles, a muscle innervated by the recurrent laryngeal nerve, without resort to needle invasion of other laryngeal musculature. 
     Even another object is to provide such an electrode and method for accurately and securely placing the electrode through the pharynx (throat) into the patient&#39;s postcricoid space without interfering with other equipment. 
     And yet another object is to provide such an electrode that is economical to manufacture, efficient in use, and particularly well adapted for the proposed use. 
     Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. 
     The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the primary embodiment of an attachable and size adjustable surface electrode for laryngeal electromyography embodying the present invention wrapped around and attached to an endotracheal tube. 
         FIG. 2  is a top view of the primary embodiment of attachable and size adjustable surface electrode for laryngeal electromyography embodying the present invention. 
         FIG. 2A  is a cross sectional view of the attachable and size adjustable surface electrode as illustrated in  FIG. 2 . 
         FIG. 3  shows the attachable and size adjustable surface electrode being trimmed or size adjusted by cutting with scissors. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring more in detail to the drawings, the detailed embodiments of the present invention are disclosed herein, however, it is to be understood that the disclosed embodiments are merely exemplary of the invention which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and is a representative basis for teaching one skilled in the art to variously employ the present invention and virtually any appropriately detailed structure. 
     The reference numeral  10  generally designates the attachable and size adjustable surface electrode for laryngeal electromyography of the present invention. The attachable and size adjustable surface electrode  10  generally consists of a flexible plate  12  having an anterior surface  14  and a posterior surface  16  specifically for inserting in the human laryngopharynx adjacent to the cricothyroideus muscles (the vocal cords). An electrical conductive plate  18  is mounted on the anterior surface  14 , to provide an electric contact with the cricothyroideus muscles. A wire  20  extends from the electrical conductive plate  18  for monitoring or delivering electrical pulses to the cricothyroideus muscles. The other end of the wire  20  is attachable to an electromyographic monitor. There are graduations  22  parallel to a center line marked on the electrical conductive plate  18 , or posterior side  16  of the flexible plate  12 , for cutting and sizing the flexible plate  12  and electrical conductive plate  18  to the size of the patient&#39;s laryngopharynx. There is an adhesive material  24  on the posterior surface  16  of the flexible plate  12  for attachment of the attachable and size adjustable surface electrode  10  to an endotracheal tube, insert device, postcricoid paddle or other such device  8 . 
     No other known device is flexible and size adjusting by cutting, and attachable to an endotracheal tube, insert device, postcricoid paddle or other such device  8  by wrapping the attachable and size adjustable surface electrode  10  around the endotracheal tube, insert device, postcricoid paddle or other such device  8  and attaching via the adhesive  24 . 
     The flexible plate  12  has an anterior surface  14  and a posterior surface  16  specifically for inserting in the human laryngopharynx adjacent to the cricothyroideus muscles (the vocal cords). The flexible plate  12  is made from a non-conductive material that is flexible and bendable so it can be wrapped about and attached to an endotracheal tube, insert device, postcricoid paddle, or other such device  8 . It could be made from a variety of material, but the preferred embodiment it is made of a thin layer of polyethylene, foam polyethylene, or some other medical grade material. Typically, the initial dimensions are 24 millimeters (mm) in width and 45 mm in length in the preferred embodiment. However, different sizes and different materials can be made based upon the intended use, size of the patient, and by market forces. 
     The electrical conductive plate  18  is mounted on the anterior surface  14  of the flexible plate  12 , to provide an electric contact with the cricothyroideus muscles. The electrical conductive plate  18  is constructed of a metallic conductive layer of silver ink, flexograph silver deposition, or similar electrically conductive medium. The electrical conductive plate  18  can be attached with the adhesive properties of the conductive material itself or it may be attached with silver loaded conductive adhesive, nonconductive acrylic resin, or other type of material or adhesive that adheres to both the electrical conductive plate  18  and the flexible plate  12 . The dimensions of the electrical conductive plate  18  are somewhat smaller than the outer dimensions of the flexible plate  12 . However, after the attachable and size adjustable surface electrode  10  is cut to size, the width of both will be approximately equal. Both the flexible plate  12  and electrical conductive plate  18  will be cut simultaneously so they should be the same width after sizing. 
     A wire  20  extends from the electrical conductive plate  18  for monitoring or delivering electrical pulses from/to the cricothyroideus muscles. One end of the wire  20  is in electrical contact with the electrical conductive plate  18 . Preferably, the wire  20  is in electrical contact with the back side along a center line of the electrical conductive plate  18  between the flexible plate  12  and the electrical conductive plate  18 . In this location the electrical contact is protected and provides a mechanically sound connection location. The wire  20  may be attached with silver loaded conductive adhesive or any other electrical conductive means. The other end of wire  20  is adapted for connection to an electrical signal receiver and monitor, such as an electromyographic monitor instrument  6 . The wire  20  typically is a flexible conductive wire in the nature of 40 gauge more or less with an insulating covering. The wire  20  is very fine in the nature and with a length of approximately 6 inches or longer to facilitate threading the same into the patient&#39;s laryngopharynx. The main purpose of the wire  20  is to provide the input of electrical signals to or from electrical conductive plate  18  to an electromyographic monitor instrument  6 . In this regard, any wire of any gauge or length fulfilling this purpose is within the scope of the invention. 
     There are a plurality of graduations  22  parallel to and on both sides of a center line on the electrical conductive plate  18 , in the preferred embodiment. The graduations  22  are for cutting and sizing the flexible plate  12  and electrical conductive plate  18  to the size of the endotracheal tube or insert device  8  appropriate for the patient&#39;s laryngopharynx. The attachable and size adjustable surface electrode  10  is easily cut and sized using scissors  4  or some other cutting device. The graduations  22  could also be marked on the posterior surface  16  of the flexible plate  12  or back side of the removable plastic film or paper  26  in other embodiments, that are not shown. The graduations  22  are typically marked on one side of center in a spaced relationship to graduations  22  marked on the other side of center. This is so an equal amount can be cut off on each side of center. The graduations  22  may or may not be marked with alphanumerical characters  28  for ease of identifying corresponding graduation marks on the opposite sides of center. Typically, the graduations  22  and alphanumerical characters if any, can be marked with ink, paint, etching, stamping, or by any method that readily shows the graduations  22  and alphanumerical characters. Any means used for marking the graduation should be considered within the scope of the invention. 
     There is a non conductive adhesive material  24  on the posterior surface  16  of the flexible plate  12  for attachment of the attachable and size adjustable surface electrode  10  to an endotracheal tube, insert device, postcricoid paddle or other such device  8 . In the preferred embodiment, the adhesive is covered with a thin film of plastic or paper  26 . The thin plastic film is peeled off so the attachable and size adjustable surface electrode  10  can be wrapped around and attached via the adhesive to an endotracheal tube, insert device, postcricoid paddle or other such device  8 . Any type of adhesive that functions to attach the attachable and size adjustable surface electrode  10  to an endotracheal tube, insert device, postcricoid paddle or other such device  8  is within the scope of the invention. 
     In use: 
     The first step is to determine the size of the patient&#39;s trachea and larynx and the type of insert device to be used. As used here an insert device  8  can be an endotracheal tube, insert device, postcricoid paddle, or other such device. The attachable and size adjustable surface electrode  10  is cut to size along graduations  22  using scissors  4  or some other cutting device. The adhesive backing is peeled off and the attachable and size adjustable surface electrode  10  is wrapped around and attached to the insert device  8 . 
     The patient is then anesthetized and the insert device  8  with the attachable and size adjustable surface electrode  10  is inserted into the patient&#39;s mouth and into his trachea. The attachable and size adjustable surface electrode  10  is positioned between the vocal cords with the attachable and size adjustable surface electrode  10  making contact with the cricothyroideus muscles. The outer end of the wire  20  is attached to an electromyographic monitor  6 . Typically, the insert device  8  has an opening longitudinally through the device to allow the patient to breathe. 
     The electromyographic monitor  6  generally is a device that will receive an electrical signal originating in the cricothyroideus muscles and transmitted thereto through the wire  20 , and provide a display of the signal. The signal receiver and monitor may comprise an oscilloscope or the like, and is preferably a mechanism which provides an audible alarm upon receipt of the electrical signal, whereby the location of the recurrent laryngeal nerve can be determined while the surgeon maintains continuous sight observation of the area of surgery. 
     The electromyographic monitor  6  or signal generator typically includes a probe and provides means for applying an electrical signal to the recurrent laryngeal nerve  22 . The signal is of a relatively low voltage, in the nature of five to forty volts, and is preferably a repetitive stimuli of low frequency, short pulses, in the nature of 4 pulses per second stimulation rate. 
     After the surgeon has made his initial incision, and is approaching the area of the recurrent laryngeal nerve, he simply applies the probe to the area in which he believes the nerve to be located. If the probe contacts the laryngeal nerve, the signal applied thereto by the signal generator  6  is transmitted through the laryngeal nerve to the cricothyroideus muscles which in turn is thereby excited. Excitement of the cricothyroideus muscles causes an electrical impulse to be generated therein and is transmitted through the electrical conductive plates  18  and the wire  20  to the signal receiver and monitor. The electrical conductive plate  20  serves as an electrical ground for the signal receiver and monitor. In the case of an audio monitor, the device shall emit popping sounds in a frequency which corresponds to the recognized warning tone emitted by signal receiver and monitor. The surgeon need only recognize the characteristic frequency of these popping sounds to know that he has located the recurrent laryngeal nerve. After having determined the location of the nerve, the surgeon can work very slowly and carefully in this area so as to insure the nerve is not injured. 
     The attachable and size adjustable surface electrode  10  may be removed from the patient by simply pulling on the insert device  8 , thereby removing the insert device  8  and the attachable and size adjustable surface electrode  10  distally through the patient&#39;s mouth. 
     It is to be understood that while we have illustrated and described certain form of our invention, it is not to be limited to the specific forms or arrangements herein described and shown.