Abstract:
Disclosed is a modular system for providing electrical stimulation, in which a first modular electrode section has a contoured back end configured to engage a contoured front end of another electrode section or a tool that may be used to place the first modular electrode section in the patient&#39;s body. The contours of the modular electrode section allow the two components to engage with one another so as to prevent their separation in the horizontal plane, and a lead extending from the first modular electrode is configured to engage keels on the top surface of the second electrode portion or tool, with such keels providing a snap-type attachment between the lead and the second electrode portion or tool, such that the two components may be joined together but easily separated from one another through the intentional separation of the lead from the keels on the second electrode portion or tool.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims benefit of U.S. Provisional Patent Application Ser. No. 61/229,774 entitled “Modular Electrode and Insertion Tool”, filed with the U.S. Patent and Trademark Office on Jul. 30, 2009 by the inventor herein, the specification of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of implantable medical electronic devices, such as electrical stimulators, epidural electrodes, defibrillators and pacemakers, and more particularly to an electrode having a modular configuration allowing multiple modular electrode segments to be joined together in combination, as well as an insertion tool to aid in the surgical implantation of such modular electrode segments. 
     BACKGROUND OF THE INVENTION 
     Many humans (and other mammals and animals) receive benefit from implantable medical devices that deliver electrical pulses to or record from desired locations within their bodies. Such medical devices may comprise, for instance, spinal cord stimulation (“SCS”) electrodes which typically comprise a small lead wire that is connected at one end to a power source and at the opposite end to a plurality of electrical contacts configured to transfer an electrical signal to the tissues that are to be stimulated. Those electrical contacts may, for instance, be situated in a paddle configured for implantation in a patient adjacent the tissue that is to be stimulated, such as along the spinal cord of a patient. SCS paddles typically have the lead wire or wires emerging from the bottom edge of the paddle, in the same plane as the body of the paddle. Also, typically there is a strain relief, molded along with the paddle, which surrounds the emerging lead or leads for approximately 5-8 mm, and beyond that the flexible leads continue onward to the power source. 
     Such paddle electrodes may be provided in a variety of configurations, with particular configurations being used for particular patient conditions. For instance, one patient&#39;s condition may require use of a single 8-electrode paddle, while another patient&#39;s condition may require use of multiple 6-electrode paddles. Thus, some instances may call for the use of multiple electrodes, wherein two or more leads are attached to a single implanted pulse generator. A common example of the use of multiple electrodes is the placement of two percutaneous SCS electrodes plugged into two corresponding ports on the implanted pulse generator. These electrodes are inserted independently into the implanted pulse generator, and while they may be anchored together subcutaneously, they are not coupled together at the ends where the stimulating contacts are located. Likewise, two or more paddle electrodes that are implanted for use with a single pulse generator are typically not coupled together. 
     When using multiple electrodes, a surgeon may suture two electrodes together to form a larger or longer array. In doing so, rather than performing two separate laminectomies at adjacent spinal levels to implant two electrodes, a single laminectomy may be performed to insert the two joined electrodes, using the lower electrode to push the upper electrode into position. Unfortunately, however, as the two electrodes remain separate elements not particularly configured for a modular assembly, this procedure can be quite difficult to perform. 
     Furthermore, while a large array of electrical contacts on a single electrode might likewise achieve the same result (i.e., providing a wider area of electrical stimulation from a single electrode assembly implanted through a single laminectomy), providing for all possibly desired large arrays would be cost-prohibitive, and likewise require the manufacture and maintenance of a stock of a large quantity of different electrodes. For instance, a large electrode, such as might be used as a thoracolumbar electrode, may be too large to use safely in the cervical spine. Similarly, insertion of a long electrode into the spine at any level may encounter an obstruction, calling for the use of a shorter electrode. Moreover, the larger array can use up contact positions on the implanted pulse generator (or recorder) which might otherwise be useful. For example, an intraspinal electrode might be supplemented by a subcutaneous electrode, with both electrodes connected to a single generator. Of course, such connection to a single generator would only be possible if there are unused contact positions available. 
     Still further, traditional electrodes may be quite difficult to manipulate during implantation. Presently available electrodes, with their irregular shapes and soft materials, are very difficult to grasp with standard surgical tools such as forceps, especially once they have been lubricated by body fluids in the surgical field. Often the surgical exposure is deep, narrow, and dark. Existing electrodes typically are not supplied with a specialized insertion tool, and attempting to manipulate them can be quite frustrating. 
     It would therefore be advantageous to provide an electrode that is configurable into varied electrical contact configurations so as to be selectively applicable to various patient conditions requiring electrical stimulation. It would also be advantageous to provide a tool suitable for aiding in the implantation and manipulation of such a variably configurable electrode. 
     SCS is just one example of the potential applications of the present invention; it also offers advantages for other implanted stimulator applications, including but not limited to motor cortex, peripheral nerve, subcutaneous, and sacral nerve roots. It is also applicable to recording from the same and additional locations in the body. 
     SUMMARY OF THE INVENTION 
     Disclosed is a modular system for providing electrical stimulation to a patient&#39;s body, in which a first modular electrode section has a contoured back end configured to engage with a contoured front end of another electrode section or a tool that may be used to place the first modular electrode section in the patient&#39;s body. The contours of the back end of the first modular electrode section and of the front end of the second electrode section or tool allow the two components to engage with one another so as to prevent their separation in the horizontal plane (i.e., the plane that contains the top surfaces of the two components). Additionally, in order to prohibit both the lateral and vertical separation of the two components, a lead extending from the first modular electrode is configured to engage keels on the top surface of the second electrode portion or tool, with such keels providing a snap-type attachment between the lead and the second electrode portion or tool, such that the two components may be joined together but easily separated from one another through the intentional separation of the lead from the keels on the second electrode portion or tool. With this construction, a surgeon may ensure that the two components remain connected to one another through the implantation process, and may likewise separate the components if and when desired to accommodate a particular application or clinical condition. 
     With regard to one aspect of a particularly preferred embodiment of the invention, a modular system for providing electrical simulation to a patient&#39;s body is provided, the modular system comprising a modular electrode section comprising an electrode body having an electrode front end, an electrode back end opposite the electrode front end, an electrode top surface, and an electrode bottom surface, the electrode back end having a contour comprising concave and convex portions, and an electrode engaging member comprising an engaging member body having an engaging member front end, an engaging member back end opposite the engaging member front end, an engaging member top surface, and an engaging member bottom surface, the engaging member front end having a contour comprising concave and convex portions that are complementary to and configured to engage with the concave and convex portions of the electrode back end. 
     With regard to another aspect of a particularly preferred embodiment of the invention, a modular electrode is provided comprising an electrode body having an electrode front end, an electrode back end opposite the electrode front end, an electrode top surface, and an electrode bottom surface, the electrode back end having a contour comprising concave and convex portions configured for engagement with complementary convex and concave portions on an electrode engaging member configured for attachment to the electrode body, a plurality of electrical contacts within one of the top surface and the bottom surface of the electrode body, and a plurality of wires extending from the plurality of electrical contacts to a lead configured for connection to an implantable medical device to transfer an electrical signal between the implantable medical device and the plurality of electrical contacts. 
     With regard to yet another aspect of a particularly preferred embodiment of the invention, an electrode engaging member configured for engaging a modular electrode is provided, the electrode engaging member comprising an engaging member body having an engaging member front end, an engaging member back end opposite the engaging member front end, an engaging member top surface, and an engaging member bottom surface, the engaging member front end having a contour comprising concave and convex portions configured for engagement with complementary convex and concave portions on a modular electrode configured for attachment to the engaging member body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying drawings in which: 
         FIG. 1  is a top view of a modular electrode assembly in accordance with an aspect of a particularly preferred embodiment of the invention. 
         FIG. 2  is a side view of the modular electrode assembly of  FIG. 1 . 
         FIG. 3  is a side view of the modular electrode assembly of  FIG. 1  according to another aspect of the invention. 
         FIG. 4  is a cross-sectional view of the modular electrode assembly of  FIG. 3 . 
         FIG. 5  is a top view of a modular electrode assembly according to another aspect of the invention. 
         FIG. 6  is a side view of the modular electrode assembly of  FIG. 5 . 
         FIG. 7  is a cross-sectional view of a portion of the modular electrode assembly of  FIG. 5 . 
         FIG. 8  is a cross-sectional view of the modular electrode assembly of  FIG. 5  along section line A-A. 
         FIG. 9  is a cross-sectional view of the modular electronic assembly of  FIG. 5  along section line B-B. 
         FIG. 10  is a side view of the modular electronic assembly of  FIG. 5  according to another aspect of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of a particular embodiment of the invention, set out to enable one to practice an implementation of the invention, and is not intended to limit the preferred embodiment, but to serve as a particular example thereof. Those skilled in the art should appreciate that they may readily use the conception and specific embodiments disclosed as a basis for modifying or designing other methods and systems for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent assemblies do not depart from the spirit and scope of the invention in its broadest form. 
     With regard to a first aspect of a particularly preferred embodiment of the invention, a modular implantable electrode is provided, such as a SCS paddle electrode, capable of being surgically implanted inside of a patient so as to transfer an electrical signal from a power source to targeted tissue in the patient. The paddle electrode is particularly configured so as to allow multiple paddle electrode sections to be longitudinally joined together in order to allow the size of an electrical contact array to be particularly configured for a specific application or patient condition. Likewise, with regard to another aspect of a particularly preferred embodiment, an insertion tool is provided for engaging such modular paddle electrode sections to positively engage a portion of at least one of those modular sections and facilitate its handling by the surgeon. 
     With reference to  FIG. 1 , a first modular paddle electrode section  100  is shown having a top surface  102 , a front end  104 , and a back end  106 . Front end  104  is shaped with concavities and convexities that may aid in the insertion of first modular paddle electrode section  100  into the designated area within a patient. For instance, copending and co-owned U.S. patent application Ser. No. 12/804,117, filed on Jul. 14, 2010 by the inventor herein describes a shaped electrode and dissecting tool having a contoured front end configured to aid in the insertion of such electrode into a patient. The specification of patent application Ser. No. 12/804,117 is incorporated herein by reference in its entirety. Similarly, back end  106  of modular paddle electrode section  100  is shaped with complementary concavities and convexities. An electrode engaging member  200 , which may comprise a second modular paddle electrode section or alternatively an insertion tool, is likewise provided, having a top surface  202 , a front end  204 , and a back end (not shown). Front end  204  has a contour comprised of concavities and convexities similar to the contour of front end  104  of modular paddle electrode section  100 , and is configured to mate with and closely engage back end  106  of first modular paddle electrode section  100  which is itself provided with a complementary contour to the concavities and convexities of front end  204  of electrode engaging member  200 . The complementary contours of back end  106  of first modular paddle electrode  100  and the front end  204  of electrode engaging member  200  allow close engagement of the two components so as to facilitate the controlled movement of first modular paddle electrode section  100  into position within the patient. 
     As shown in  FIG. 2 , a complementary mating configuration may also be provided in the vertical planes of back end  106  of first modular paddle electrode section  100  and front end  204  of electrode engaging member  200 . More particularly, those ends may be curved so as to closely engage one another so as to resist separation in the vertical direction (as viewed in  FIG. 2 ). While  FIG. 2  particularly shows curved faces on back end  106  of first modular paddle electrode section  100  and on front end  204  of electrode engaging member  200 , those of ordinary skill in the art will recognize that other mating contours, such as angled faces and edges and the like, may likewise be used to allow the two modular sections  100  and  200  to fit closely with one another, without departing from the spirit and scope of the invention. 
     As shown in  FIG. 2 , first modular paddle electrode section  100  may have a lead  110  attached thereto which is configured to transfer an electrical signal from an implanted pulse generator to electrical contacts on first modular paddle electrode section  100 . As is described in co-pending and co-owned U.S. application Ser. No. 12/804,560 filed by the inventor herein on Jul. 23, 2010, titled “Electrode Having Erectable Lead,” the specification of which is incorporated herein by reference in its entirety, lead  110  may emerge from the top surface  102  of modular paddle electrode section  100  so as to not interfere with the mating of back end  106  of first modular paddle electrode section  100  with front end  204  of electrode engaging member  200 . Optionally, one or more sutures  300  may be used to suture emerging lead  110  to electrode engaging member  200  after its front end  204  has been mated with the back end  106  of first modular paddle electrode  100 . 
     Alternatively, and as shown in  FIGS. 3 and 4 , first modular paddle electrode section  100  may be provided keels  120  on its top surface  102 . Keels  120  are formed so as to provide a channel which closely receives lead  110 , such that after lead  110  is snapped into place, keels  120  hold lead  110  in place absent the application of a significant force to withdraw it from the keels. For instance, keels  120  may have concave surfaces on their interiors which closely follow the outer dimension of lead  110 . A slit  122  is provided between keels  120  through which lead  110  may be inserted. Keels  220  on electrode engaging member  200  are similarly configured, again having a slit through which lead  110  may be inserted, thus helping to hold electrode engaging member  200  to first modular paddle electrode section  100  after their respective front end  204  and back end  106  are mated with one another. 
     With regard to another aspect of the invention, and as shown in  FIGS. 5 and 6 , a strain relief  130  is provided around lead  110 , which strain relief  130  extends outward beyond back end  106  of first modular paddle electrode section  100 . Electrode engaging member  200  is again provided keels  220 , again having a slit at the top surface between the two keels  220  capable of receiving lead  110 . The front most portions of keels  220  are of similar configuration to keels  120  on first modular paddle electrode section  100 , comprising two thin walls  222  configured to receive and hold strain relief  130  when the two modular paddle electrode sections  100  and  200  are mated with one another. As best seen in  FIG. 5 , walls  222  at their back ends open into a wider portion of keels  220 , with keels  220  having such wider thickness throughout the rest of their length along the top surface  202  of electrode engaging member  200 , with a slit (as mentioned above) configured to receive and hold lead  110 . As keels  220  are thus configured to receive both lead  110  and the back-most portion of strain relief  130 , once the first modular paddle electrode  100  is mated with electrode engaging member  200 , and strain relief  130  and lead  110  are snapped between the appropriate sections of keels  220 , the two sections  100  and  200  will likewise be held to one another by such connection. 
     As shown in the cross-sectional view of  FIG. 7  (showing first modular paddle electrode section  100  without strain relief  130  installed), keels  120  extend upward from top surface  102  and at an angle less than ninety degrees to top surface  120 , thus leaning toward one another to form a trapezoidal opening between them. Strain relief  130  is preferably provided a complementary trapezoidal external configuration, such that strain relief  130  may be snapped into the opening formed between keels  120 . Those of ordinary skill in the art will appreciate that shapes other than a trapezoidal configuration, such as curved or angled cross-sections that are configured to removably hold strain relief  130  to first modular paddle electrode  100 , may likewise be implemented without departing from the spirit and scope of the invention. 
     As shown in the cross-sectional view of  FIG. 8  taken along section line A-A of  FIG. 5 , strain relief  130  is shown positioned between keels  120 , with lead  110  extending outward from strain relief  130 . Likewise, as shown in the cross-sectional view of  FIG. 9  taken along section line B-B of  FIG. 5 , lead  110  is shown positioned within the opening between keels  220 , with a narrow slit  230  positioned at the top between the top portions of keels  220 , through which lead  110  may be inserted. In the case where electrode engaging member  200  is configured as a second electrode section that is to be mated with first modular paddle electrode section  100 , electrode engaging member  200  may be formed from a soft silicone elastomer material, in which case slit  230  may be very narrow. In the event that electrode engaging member  200  is configured as an insertion tool that is to be mated with first modular paddle electrode section  100 , a hard plastic would likely comprise such insertion tool, in which case a wider slit  230  would be desirable. Lead  110  typically comprises a plurality of wires encased within a plastic sheath which is somewhat compressible, such that it may snap into a slot in either of the foregoing configurations. 
     Still further, as shown in the side view of  FIG. 10 , and with regard to another aspect of the invention, strain relief  130  and lead  110  may be pulled up and out of first modular paddle electrode section  100  over a portion of its length in order to facilitate assembly with electrode engaging member  200 . 
     Those of ordinary skill in the art will recognize that by providing electrode engaging member  200  with a front end  204  configured to mate with the back end  106  of first modular paddle electrode section  100 , and by providing such components with mating keels and slots as described above to engage one another, the combined features of the contoured ends of each component, the strain relief  130  and lead  110  and keels  120  and  220  will offer a much better grip to hold the two components together than has been previously achieved. 
     It should be understood that various other characteristics of the novel modular electrode of the current invention may be changed without departing from the spirit and scope of the present invention. For instance, additional features may be provided to further supplement the connection between the two components, such as a sleeve around the joint (which sleeve could be removable during or after insertion), or additional tabs, stiffening wires, or the like with corresponding receptacles in first modular paddle electrode section  100 . Likewise, additional connections may be provided between first modular paddle electrode section  100  and electrode engaging member  200  to further supplement their connection. Still further, the foregoing configurations could likewise be used to join electrodes not only end to end, as described herein, but likewise side by side, or otherwise as may be apparent to those of ordinary skill in the art. 
     It is believed that the present invention and many of its attendant advantages will be understood by the forgoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the spirit and scope of the invention or without sacrificing all of its material advantages. The form herein before described is merely an explanatory embodiment thereof.