Abstract:
An implantable stimulation system including an epidural lead for spinal cord stimulation that includes a paddle having an array of electrodes coupled to conductors within the lead body. The paddle includes score lines that extend along the length and width of either the front or back facets of the paddle portion. The score lines increase the flexibility of the paddle in both the length and width directions which facilitate the implantation of the paddle within the epidural space of the spinal cord, and further permits the paddle to conform more uniformly to the target area of implantation to minimize the gap between the electrodes and targeted fibers.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/608,380, filed Mar. 8, 2012, the disclosures of which are fully incorporated herein by reference for all purposes. 
     
    
     TECHNICAL FIELD 
       [0002]    The present application relates generally to implantable medical stimulators and more particularly to a paddle lead having a plurality of electrodes wherein the surfaces of the paddle portion are scored in a manner to increase the flexibility of the paddle portion to facilitate the insertion of paddle lead within the epidural space and to enable the paddle lead to conform to the implant site to optimize electrical coupling between the electrodes and the spinal cord. 
       BACKGROUND 
       [0003]    Neurostimulation systems are devices that generate electrical pulses and deliver the pulses to nerve tissue to treat a variety of disorders. Neurostimulation systems generally include a pulse generator and one or more leads. The pulse generator is typically implemented using a metallic housing that encloses circuitry for generating the electrical pulses, control circuitry, communication circuitry, a rechargeable battery, etc. The pulse generation circuitry is coupled to one or more stimulation leads through electrical connections provided in a “header” of the pulse generator. Specifically, feed-through wires typically exit the metallic housing and enter into a header structure of a moldable material. Within the header structure, the feed-through wires are electrically coupled to annular electrical connectors. The header structure holds the annular connectors in a fixed arrangement that corresponds to the arrangement of terminals on a stimulation lead. 
         [0004]    Spinal cord stimulation (SCS) is an example of neurostimulation in which electrical pulses are delivered to nerve tissue in the spine typically for the purpose of chronic pain control. While a precise understanding of the interaction between the applied electrical energy and the nervous tissue is not fully appreciated, it is known that application of an electrical field to spinal nervous tissue can effectively mask certain types of pain transmitted from regions of the body associated with the stimulated nerve tissue. Specifically, applying electrical energy to the spinal cord associated with regions of the body afflicted with chronic pain can induce “paresthesia” (a subjective sensation of numbness or tingling) in the afflicted bodily regions. Thereby, paresthesia can effectively mask the transmission of non-acute pain sensations to the brain. 
         [0005]    Also, each exterior region, or each dermatome, of the human body is associated with a particular spinal nerve root at a particular longitudinal spinal position. The head and neck regions are associated with C2-C8, the back region extends from C2-S3, the central diaphragm is associated with spinal nerve roots between C3 and C5, the upper extremities correspond to C5 and T1, the thoracic wall extends from T1 to T11, the peripheral diaphragm is between T6 and T11, the abdominal wall is associated with T6-L1, lower extremities are located from L2 to S2, and the perineum from L4 to S4. In conventional neurostimulation, when a patient experiences pain in one of these regions, a neurostimulation lead is implanted adjacent to the spinal cord at the corresponding spinal position. 
         [0006]    Positioning of an applied electrical field relative to a physiological midline is also important. Nerve fibers extend between the brain and nerve root along the same side of the dorsal column as the peripheral areas of the fibers represent. Pain that is concentrated on only one side of the body is “unilateral” in nature. To address unilateral pain, electrical energy is applied to neural structures on the side of a dorsal column that directly corresponds to a side of the body subject to pain. Pain that is present on both sides of a patient is “bilateral.” Accordingly, bilateral pain is addressed through application of electrical energy along both sides of the column and/or along a patient&#39;s physiological midline. 
         [0007]    Percutaneous leads and laminotomy leads are the two most common types of lead designs that provide conductors that deliver stimulation pulses from an implantable pulse generator (IPG) to distal electrodes adjacent to the nerve tissue. As shown in  FIG. 1A , conventional percutaneous lead  100  includes electrodes  101  that substantially conform to the body of the body portion of the lead. Due to the relatively small profile of percutaneous leads, percutaneous leads are typically positioned above the dura layer through the use of a Touhy-like needle. Specifically, the Touhy-like needle is passed through the skin, between desired vertebrae to open above the dura layer for the insertion of the percutaneous lead. 
         [0008]    As shown in  FIG. 1B , conventional laminotomy or paddle lead  150  has a paddle configuration and typically possesses a plurality of electrodes  151  arranged in one or more columns. Multi-column laminotomy leads enable reliable positioning of a plurality of electrodes. Also, laminotomy leads offer a more stable platform that tends to migrate less after implantation and that is capable of being sutured in place. Laminotomy leads also create a uni-directional electrical field and, hence, can be used in a more electrically efficient manner than conventional percutaneous leads. Due to their dimensions and physical characteristics, conventional laminotomy leads require a surgical procedure for implantation. The surgical procedure (a partial laminectomy) is evasive and requires the resection and removal of certain vertebral tissue to allow both access to the dura and proper positioning of a laminotomy lead. 
       SUMMARY 
       [0009]    Some representative embodiments are directed to the use of a paddle structure to apply electrical stimulation to spinal nervous tissue to treat a variety of diseases and/or conditions, for example pain or chronic pain. A stimulation paddle lead is implanted in the patient with electrodes in the epidural space of the patient. The paddle portion of the paddle lead is elongated shaped with lengthwise and widthwise scoring on at least one of the front and back faces of the paddle portion . 
         [0010]    The foregoing has outlined rather broadly certain features and/or technical advantages in order that the detailed description that follows may be better understood. Additional features and/or advantages will be described hereinafter which form the subject of the claims. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the appended claims. The novel features, both as to organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIGS. 1A and 1B  depict a conventional percutaneous lead and a convention paddle lead. 
           [0012]      FIG. 2  depicts a planar view of a paddle lead according to one representative embodiment. 
           [0013]      FIG. 3  depicts a system for implantable pulse generator with a paddle lead in communication with a wireless programming device according to one representative embodiment. 
           [0014]      FIG. 4  depicts a stimulation paddle according to a representative embodiment with length and width scoring on the face and extending to the edges of paddle portion. 
           [0015]      FIG. 5  depicts a stimulation paddle according to yet another representative embodiment with the length and width scoring on the face within the perimeter of the edges of the paddle portion. 
           [0016]      FIG. 6  depicts a stimulation paddle according to a representative embodiment with length and width scoring on the rear and extending to the edges of paddle portion. 
           [0017]      FIG. 7  depicts a stimulation paddle according to yet another representative embodiment with the length and width scoring on the face within the perimeter of the edges of the paddle portion. 
           [0018]      FIGS. 8A and 8B  depict the front and back of a stimulation paddle according to yet another representative embodiment with the length scoring on the face and the width scoring on the back with the scoring extending to the edges of the paddle portion. 
           [0019]      FIGS. 9A and 9B  depict the front and back of a stimulation paddle according to yet another representative embodiment with the length scoring on the face and the width scoring on the back with the scoring within the perimeter of the edges of paddle portion. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Referring now to  FIG. 2 , there is depicted a laminotomy lead  200  that can be used for spinal cord stimulation or stimulation of spinal nervous tissue to treat a variety of diseases and/or conditions, for example, but not limited to pain (e.g., peripheral pain), more specifically chronic pain, CRSII or CRSI. Laminotomy or paddle lead  200  includes proximal end  210  and distal end  220 . Proximal end  210  includes a plurality of electrically conductive terminals  212 . Distal end  220  includes a plurality of electrically conductive electrodes  222  (only 3 of the electrodes have been annotated for the sake of clarity) arranged within a flat, thin, paddle-like structure  230 . The electrodes  220  are mutually separated by insulative material of the paddle. The paddle structure  230  itself may have a width such that it spans the entire dorsal column or fits within the epidural space. Those of skill in the art are cognizant that the size of the dorsal column and epidural space can vary among individuals as well as within an individual. Thus, depending upon the desired implantation site, thoracic or cervical, a paddle structure may be designed to fit into the desired space such that it at least covers the anatomical and physiological midline of the patient. 
         [0021]    Since the paddle structure  230  can be as wide as the dorsal column or epidural space, the electrodes  222  likewise may have a width such that the combination of the size and number of electrodes span the width of paddle. The width of the electrode array can be a width that spans the anatomical and physiological midline. The length of the electrodes may vary as well such that the length comprises a length that is appropriate for the length of the paddle structure. In one such example, but not by way of limitation, the paddle structure  230  has a width of about 11 mm with the electrodes  222  having an approximate width of about 0.5 mm to about 1.5 mm, or any range there between, more particularly; the width of the electrode can be about 1 mm having an approximate electrode array width of about 9 mm. 
         [0022]    Yet further, the spacing of the electrodes  222  may vary as well depending upon the paddle structure and the desired usage or placement of the structure. For a paddle structure  230  adapted for implantation within a cervical vertebral level, good results have been achieved with the electrodes being spaced apart approximately 1.5 mm laterally and 2.5 mm longitudinally. For a paddle structure  230  adapted for implantation within a thoracic vertebral level, good results have been achieved with the electrodes  222  being spaced apart by 1.0 mm laterally and 2 mm to 3 mm longitudinally. Conductors  240  (which are embedded within the insulative material of the lead body) electrically connect electrodes  222  to terminals  212 . 
         [0023]    Terminals  212  and electrodes  222  are preferably formed of a non-corrosive, highly conductive material. Examples of such material include stainless steel, MP35N, platinum, and platinum alloys. In a preferred embodiment, terminals  212  and electrodes  222  are formed of a platinum-iridium alloy. Each conductor  240  is formed of a conductive material that exhibits desired mechanical properties of low resistance, corrosion resistance, flexibility, and strength. While conventional stranded bundles of stainless steel, MP35N, platinum, platinum-iridium alloy, drawn-brazed silver (DBS) or the like can be used, a preferred embodiment uses conductors  240  formed of multi-strands of drawn-filled tubes (DFT). Each strand is formed of a low resistance material and is encased in a high strength material (preferably, metal). A selected number of “sub-strands” are wound and coated with an insulative material. With regard to the operating environment of representative embodiments, such insulative material protects the individual conductors  240  if its respective sheath  242  was breached during use. 
         [0024]    In addition to providing the requisite strength, flexibility, and resistance to fatigue, conductors  240  formed of multi-strands of drawn-filled tubes, in accordance with the above description, provide a low resistance alternative to other materials. Specifically, a stranded wire, or even a coiled wire, of approximately 60 cm and formed of MP35N or stainless steel or the like would have a measured resistance in excess of 30 ohms. In contrast, for the same length, a wire formed of multi-strands of drawn-filled tubes could have a resistance less than 4 ohms. 
         [0025]    Sheaths  242  and paddle structure  230  are preferably formed from a medical grade, substantially inert material, for example, polyurethane, silicone, or the like. Importantly, such material should be non-reactive to the environment of the human body, provide a flexible and durable (i.e., fatigue resistant) exterior structure for the components of paddle lead  200 , and insulate adjacent terminals  212  and/or electrodes  222 . Additional structure (e.g., a nylon mesh, a fiberglass substrate) (not shown) can be internalized within the paddle structure  230  to increase its overall rigidity of the paddle structure  230 . 
         [0026]      FIG. 3  depicts paddle lead  200  coupled to IPG  300  which is in wireless communication with programmer device  310 . An example of a commercially available IPG is the Eon™ Rechargeable IPG manufactured by Advanced Neuromodulation Systems, Inc, although any suitable IPG, such as RF powered devices, could be alternatively employed. As shown in  FIG. 3 , paddle lead  200  is coupled to the headers ports  302  of IPG  300 . Each header port  302  electrically couples the respective terminals  212  (shown in  FIG. 2 ) to a switch matrix (not shown) within IPG  300 . 
         [0027]    The switch matrix selectively connects the pulse generating circuitry (not shown) of IPG  300  to the various terminals  212 , and, hence to the electrodes  222 . The sealed portion  304  of IPG  300  contains the pulse generating circuitry, communication circuitry, control circuitry, and battery (not shown) within an enclosure to protect the components after implantation within a patient. The control circuitry may comprise a microprocessor, one or more ASICs, and/or any suitable circuitry for controlling the pulse generating circuitry. The control circuitry controls the pulse generating circuitry to apply electrical pulses to the patient via electrodes  222  of paddle lead  200  according to multiple pulse parameters (e.g., pulse amplitude, pulse width, pulse frequency, etc.). The electrodes  222  are set to function as cathodes or anodes or set to a high-impedance state for a given pulse according to the couplings provided by the switch matrix. The electrode states may be changed between pulses. 
         [0028]    When paddle lead  200  is initially implanted within the patient, a determination of the set(s) of pulse parameters and the electrode configuration(s) that effectively treat the patient&#39;s condition is made. The determination or programming typically occurs through a physician&#39;s interaction with configuration software  312  executed on the programmer device  310 . Configuration software  312  steps the physician through a number of parameters and electrode configurations. In preferred embodiments, the electrode configurations are stepped through by laterally “steering” the electrical field by moving the anodes and/or cathodes along a row of the paddle as discussed above. The patient provides feedback to the physician regarding the perceived stimulation that occurs in response the pulse parameters and electrode configuration(s). The physician effects changes to the parameters and electrode configuration(s) until optimal pulse parameters and electrode configuration(s) are determined. The final pulse parameters and configurations are stored within IPG  300  for subsequent use. The pulse parameters and configurations are used by IPG  300  to control the electrical stimulation provided to the patient via paddle lead  200 . 
         [0029]    Referring now to  FIGS. 4-9 , there is depicted multiple embodiments of paddle portions  230  with various configurations of scored surfaces on the paddle portion  230 . The scored surfaces of the present invention are utilized to enhance the flexibility of paddle portion  230  while maintaining a desired amount of rigidity. The lengthwise score lines enhance the flexibility of paddle portion  230  about the length of the paddle portion  230 , while the widthwise score lines enhance the flexibility of paddle portion  230  about the width of the paddle portion  230 . 
         [0030]    Referring now to  FIGS. 4 and 5 , there is depicted the front surface or face  231  of paddle structure  230 . As illustrated paddle structure  230  includes an array of electrodes  222  that are spaced apart longitudinally along the length of paddle structure  230  from end  250  towards end  252 , and are spaced apart across the width of paddle structure  230 . The spacing of the electrodes  222  can be set accordingly to the target implant site and the needed stimulation. Leads  244  are connected to paddle structure  230  and connect thereto in a generally longitudinal alignment with the length of paddle structure  230 . 
         [0031]    As illustrated in  FIG. 4 , the front surface or face  231  of paddle structure  230  includes lengthwise or longitudinal score lines  410  that extend between ends  250  and  252  from edge to edge, and further includes widthwise or latitudinal score lines  412  that extend between sides  251  and  253  from edge to edge. Score lines  410  and  412  extend intermediate each of the electrodes  222  to permit flexing of paddle portion  230  and to substantially reduce or eliminate damage to electrodes  222  as a result of the flexing of paddle portion  230 . 
         [0032]    As illustrated in  FIG. 5 , the front surface or face  231  of paddle structure  230  includes lengthwise or longitudinal score lines  510  that extend between ends  250  and  252 , but do not extend from edge to edge, but rather extend within the perimeter of paddle structure  230 . Paddle structure  230  further includes widthwise or latitudinal score lines  512  that extend between sides  251  and  253 , but do not extend from edge to edge, but rather extend within the perimeter of paddle structure  230 . 
         [0033]    Referring now to  FIGS. 6 and 7 , there is depicted the back or rear surface  232  of paddle structure  230 . Although not illustrated in  FIGS. 6 and 7 , as with embodiments depicted in  FIGS. 4 and 5 , the opposing side or face of paddle structure  230  includes an array of electrodes  222  that are spaced apart longitudinally along the length of paddle structure  230  from end  250  towards end  252 , and are spaced apart across the width of paddle structure  230 . The spacing of the electrodes  222  can be set accordingly to the target implant site and the needed stimulation. Leads  244  are connected to paddle structure  230  and connect thereto in a generally longitudinal alignment with the length of paddle structure  230 . Score lines  510  and  512  extend intermediate each of the electrodes  222  to permit flexing of paddle portion  230  and to substantially reduce or eliminate damage to electrodes  222  as a result of the flexing of paddle portion  230 . 
         [0034]    As illustrated in  FIG. 6 , the back or rear surface  232  of paddle structure  230  includes lengthwise or longitudinal score lines  610  that extend between ends  250  and  252  from edge to edge, and further includes widthwise or latitudinal score lines  712  that extend between sides  251  and  253  from edge to edge. 
         [0035]    As illustrated in  FIG. 7 , the back or rear surface  232  of paddle structure  230  includes lengthwise or longitudinal score lines  710  that extend between ends  250  and  252 , but do not extend from edge to edge, but rather extend within the perimeter of paddle structure  230 . Paddle structure  230  further includes widthwise or latitudinal score lines  712  that extend between sides  251  and  253 , but do not extend from edge to edge, but rather extend within the perimeter of paddle structure  230 . 
         [0036]    Referring now to  FIGS. 8A and 8B , there is depicted the front surface or face  231  and the back or rear surface  232  of paddle structure  230 . As illustrated paddle structure  230  includes an array of electrodes  222  that are spaced apart longitudinally along the length of paddle structure  230  from end  250  towards end  252 , and are spaced apart across the width of paddle structure  230 . The spacing of the electrodes  222  can be set accordingly to the target implant site and the needed stimulation. Leads  244  are connected to paddle structure  230  and connect thereto in a generally longitudinal alignment with the length of paddle structure  230 . 
         [0037]    The front surface or face  231  of paddle structure  230  includes lengthwise or longitudinal score lines  810  that extend between ends  250  and  252  from edge to edge. The back or rear surface  232  of paddle structure  230  includes widthwise or latitudinal score lines  812  that extend between sides  251  and  253  from edge to edge. 
         [0038]    Referring now to  FIGS. 9A and 9B , there is depicted the front surface or face  231  and the back or rear surface  232  of paddle structure  230 . As illustrated paddle structure  230  includes an array of electrodes  222  that are spaced apart longitudinally along the length of paddle structure  230  from end  250  towards end  252 , and are spaced apart across the width of paddle structure  230 . The spacing of the electrodes  222  can be set accordingly to the target implant site and the needed stimulation. Leads  244  are connected to paddle structure  230  and connect thereto in a generally longitudinal alignment with the length of paddle structure  230 . 
         [0039]    The front surface or face  231  of paddle structure  230  includes lengthwise or longitudinal score lines  910  that extend between ends  250  and  252 , but do not extend from edge to edge, but rather extend within the perimeter of paddle structure  230 . The back or rear surface  232  of paddle structure  230  includes widthwise or latitudinal score lines  912  that extend between sides  251  and  253 , but do not extend from edge to edge, but rather extend within the perimeter of paddle structure  230 . 
         [0040]    Although not illustrated, it is contemplated that other embodiments of paddle structure  230  could be implemented with the lengthwise or longitudinal score lines being on the rear surface and the widthwise or latitudinal score lines being or the front surface or face of paddle structure  230 , or could be further implemented with various combination of placement score lines on the front and back surfaces of paddle structure  230  depending on the desired amount of flexibility of paddle structure  230 . 
         [0041]    It is further contemplated that with any particular configuration of paddle structure  230  each of the following can vary depending upon the desired flexibility of the paddle structure  230  as well as the length and width of the paddle structure  230 , and further depending upon the number and placement of electrodes: the length of each of the score lines; the number of the score lines; and the lengthwise and widthwise placement of the score lines. It is also contemplated that the score lines need not be of continuous length, rather some or all of the score lines could also be dashed with uniform or varying lengths of dashes. 
         [0042]    For spinal cord stimulation, paddle portion  230  is implanted within the epidural space, outside the dura matter of the spinal cord with the face or front surface  231  of paddle portion  230  proximate to or facing the dura matter. The score lines of paddle portion facilitate the bending or shaping of paddle portion  230  to match the posterior shape of the epidural space. The enables the posterior side of the epidural space to assist in containing the paddle portion  230  more evenly flat against the dura matter. It further enables the face portion  231  to sit more uniformly, both in the longitudinal and latitudinal directions, against the dura matter. 
         [0043]    During the implantation of the paddle portion  230  into the epidural space of the spinal cord the score lines facilitate the implantation by being flexible enough to improve the maneuverability of the paddle portion  230 , while maintaining enough rigidity to insert the paddle portion into the epidural space of the spinal cord. 
         [0044]    Although certain representative embodiments and advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate when reading the present application, other processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the described embodiments may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.