Patent Publication Number: US-11020586-B2

Title: Distally curved electrical stimulation lead and methods of making and using

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/900,889 filed on May 23, 2013, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 61/651,830 filed on May 25, 2012, both of which are incorporated herein by reference. 
    
    
     FIELD 
     The present invention is directed to the area of implantable electrical stimulation systems and methods of making and using the systems. The present invention is also directed to implantable electrical stimulation leads having a distal end formed in a hook or coil shape to fit around tissue to be stimulated, as well as methods of making and using the leads and electrical stimulation systems containing the leads. 
     BACKGROUND 
     Implantable electrical stimulation systems have proven therapeutic in a variety of diseases and disorders. For example, spinal cord stimulation systems have been used as a therapeutic modality for the treatment of chronic pain syndromes. Peripheral nerve stimulation has been used to treat chronic pain syndrome and incontinence, with a number of other applications under investigation. Functional electrical stimulation systems have been applied to restore some functionality to paralyzed extremities in spinal cord injury patients. 
     Stimulators have been developed to provide therapy for a variety of treatments. A stimulator can include a control module (with a pulse generator), one or more leads, and an array of stimulator electrodes on each lead. The stimulator electrodes are in contact with or near the nerves, muscles, or other tissue to be stimulated. The pulse generator in the control module generates electrical pulses that are delivered by the electrodes to body tissue. 
     BRIEF SUMMARY 
     One embodiment is an implantable electrical stimulation lead including a lead body having a distal end, a proximal end, and a longitudinal length, wherein the distal end of the lead body is formed into a curved hook; a plurality of electrodes disposed along the curved hook at the distal end of the lead body; a plurality of terminals disposed on the proximal end of the lead body; and a plurality of conductors, each conductor electrically coupling at least one of the electrodes to at least one of the terminals. 
     Another embodiment is a method of implanting an electrical stimulation lead including providing the electrical stimulation lead described above and implanting the electrical stimulation lead with the curved hook disposed around a dorsal root ganglion of a patient. A portion of the lead adjacent to the distal end extends at an angle of at least 45° with respect to a dorsal root extending from the dorsal root ganglion. 
     A further embodiment is an implantable electrical stimulation lead including a lead body having a distal end, a proximal end, and a longitudinal length; a plurality of electrodes disposed along the distal end of the lead body; a plurality of terminals disposed on the proximal end of the lead body; a plurality of conductors, each conductor electrically coupling at least one of the electrodes to at least one of the terminals; and a bendable shaping member disposed within at least the distal end of the lead body. The bendable shaping member is reversibly bendable and permits formation of a hook or coil shape in the distal end of the lead body by bending of the distal end of the lead body into the hook or coil shape. The bendable shaping member is configured and arranged to retain the distal end of the lead body in the hook or coil shape without external force being applied. 
     Yet another embodiment is a method of implanting an electrical stimulation lead including providing the electrical stimulation lead of preceding paragraph; shaping the distal end of the electrical stimulation lead into a hook or coil shape by bending the bendable shaping member; and implanting the electrical stimulation lead with the distal end in the hook or coil shape disposed around a dorsal root ganglion of a patient. 
     Another embodiment is a method of implanting a lead including providing a lead comprising a lead body having a distal end, a proximal end, and a longitudinal length, a plurality of electrodes disposed along the distal end of the lead body, a plurality of terminals disposed on the proximal end of the lead body, and a plurality of conductors, each conductor electrically coupling at least one of the electrodes to at least one of the terminals. The method also includes inserting a guidewire or stylet into the lead; and implanting the lead into the patient and around at least a portion of dorsal root ganglion of the patient using the guidewire or stylet to shape the distal end of the lead body into a hook or coil situated around the portion of the dorsal root ganglion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings. In the drawings, like reference numerals refer to like parts throughout the various figures unless otherwise specified. 
       For a better understanding of the present invention, reference will be made to the following Detailed Description, which is to be read in association with the accompanying drawings, wherein: 
         FIG. 1  is a schematic view of one embodiment of an electrical stimulation system, according to the invention; 
         FIG. 2A  is a schematic view of one embodiment of a proximal portion of a lead and a control module of an electrical stimulation system, according to the invention; 
         FIG. 2B  is a schematic view of one embodiment of a proximal portion of a lead and a lead extension of an electrical stimulation system, according to the invention; 
         FIG. 3A  is a schematic transverse cross-sectional view of spinal nerves extending from a spinal cord, the spinal nerves including dorsal root ganglia; 
         FIG. 3B  is a schematic perspective view of a portion of the spinal cord of  FIG. 3A  disposed in a portion of a vertebral column with the dorsal root ganglia of  FIG. 3A  extending outward from the vertebral column; 
         FIG. 3C  is a schematic top view of a portion of the spinal cord of  FIG. 3A  disposed in a vertebral foramen defined in a vertebra of the vertebral column of  FIG. 3B , the vertebra also defining intervertebral foramina extending between an outer surface of the vertebra and the vertebral foramen, the intervertebral foramina providing an opening through which the dorsal root ganglia of  FIG. 3B  can extend outward from the spinal cord of  FIG. 3B ; 
         FIG. 3D  is a schematic side view of two vertebrae of the vertebral column of  FIG. 3B , the vertebrae defining an intervertebral foramen through which the dorsal root ganglia of  FIG. 3B  can extend outward from the spinal cord of  FIG. 3B ; 
         FIG. 4A  is a schematic perspective view of a portion of the spinal cord of  FIG. 3A  disposed in a portion of a vertebral column with the dorsal root ganglia of  FIG. 3A  extending outward from the vertebral column and one embodiment of a lead having distal end with a hook shape disposed around a dorsal root ganglion, according to the invention; 
         FIG. 4B  is a schematic perspective view of a portion of the spinal cord of  FIG. 3A  disposed in a portion of a vertebral column with the dorsal root ganglia of  FIG. 3A  extending outward from the vertebral column and another embodiment of a lead having distal end with a coil shape disposed around a dorsal root ganglion, according to the invention; 
         FIG. 5A  is a schematic perspective view of one embodiment of a distal end of an electrical stimulation lead formed in a hook shape, according to the invention; 
         FIG. 5B  is a schematic perspective view of another embodiment of a distal end of an electrical stimulation lead formed in a hook shape, according to the invention; 
         FIG. 6A  is a schematic side view of one embodiment of a distal portion of an electrical stimulation lead with a bendable shaping member disposed therein, according to the invention; 
         FIG. 6B  is a schematic side view of the electrical stimulation lead of  FIG. 6A  with the distal end of the lead bent into a hook shape using the bendable shaping member, according to the invention; 
         FIG. 7A  is a schematic side view of one embodiment of a distal portion of an electrical stimulation lead, according to the invention; 
         FIG. 7B  is a schematic side view of the electrical stimulation lead of  FIG. 7A  with the distal end of the lead bent into a hook shape using a guidewire or stylet inserted into the lead, according to the invention; 
         FIG. 8A  is a schematic side view of one embodiment of a distal portion of an electrical stimulation lead with guidewire or stylet inserted therein, according to the invention; 
         FIG. 8B  is a schematic side view of the electrical stimulation lead of  FIG. 8A  with the distal end of the lead bent into a hook shape using a curved inner member of the guidewire or stylet, according to the invention; 
         FIG. 9  is a schematic overview of one embodiment of components of a stimulation system, including an electronic subassembly disposed within a control module, according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is directed to the area of implantable electrical stimulation systems and methods of making and using the systems. The present invention is also directed to implantable electrical stimulation leads having a distal end formed in a hook or coil shape to fit around tissue to be stimulated, as well as methods of making and using the leads and electrical stimulation systems containing the leads. 
     Suitable implantable electrical stimulation systems include, but are not limited to, a least one lead with one or more electrodes disposed on a distal end of the lead and one or more terminals disposed on one or more proximal ends of the lead. Leads include, for example, percutaneous leads. Examples of electrical stimulation systems with leads are found in, for example, U.S. Pat. Nos. 6,181,969; 6,516,227; 6,609,029; 6,609,032; 6,741,892; 7,244,150; 7,450,997; 7,672,734; 7,761,165; 7,783,359; 7,792,590; 7,809,446; 7,949,395; 7,974,706; 8,175,710; 8,224,450; 8,271,094; 8,295,944; 8,364,278; and 8,391,985; U.S. Patent Applications Publication Nos. 2007/0150036; 2009/0187222; 2009/0276021; 2010/0076535; 2010/0268298; 2011/0004267; 2011/0078900; 2011/0130817; 2011/0130818; 2011/0238129; 2011/0313500; 2012/0016378; 2012/0046710; 2012/0071949; 2012/0165911; 2012/0197375; 2012/0203316; 2012/0203320; 2012/0203321; and 2012/0316615; and U.S. patent application Ser. Nos. 12/177,823; 13/667,953; and 13/750,725, all of which are incorporated by reference. 
       FIG. 1  illustrates schematically one embodiment of an electrical stimulation system  100 . The electrical stimulation system includes a control module (e.g., a stimulator or pulse generator)  102  and at least one lead  106  coupled to the control module  102 . Each lead  106  typically includes an array of electrodes  134 . The control module  102  typically includes an electronic subassembly  110  and an optional power source  120  disposed in a sealed housing  114 . The control module  102  typically includes a connector  144  ( FIG. 2A , see also  222  and  250  of  FIG. 2B ) into which the proximal end of the one or more leads  106  can be plugged to make an electrical connection via conductive contacts on the control module  102  and terminals (e.g.,  210  in  FIG. 2A and 236  of  FIG. 2B ) on each of the one or more leads  106 . In at least some embodiments, a lead is isodiametric along a longitudinal length of the lead  106 . In addition, one or more lead extensions  224  (see  FIG. 2B ) can be disposed between the one or more leads  106  and the control module  102  to extend the distance between the one or more leads  106  and the control module  102  of the embodiment shown in  FIG. 1 . 
     The electrical stimulation system or components of the electrical stimulation system, including one or more of the leads  106  and the control module  102 , are typically implanted into the body of a patient. The electrical stimulation system can be used for a variety of applications including, but not limited to, brain stimulation, neural stimulation, spinal cord stimulation, muscle stimulation, and the like. 
     The electrodes  134  can be formed using any conductive, biocompatible material. Examples of suitable materials include metals, alloys, conductive polymers, conductive carbon, and the like, as well as combinations thereof. In at least some embodiments, one or more of the electrodes  134  are formed from one or more of: platinum, platinum iridium, palladium, palladium rhodium, or titanium. The number of electrodes  134  in the array of electrodes  134  may vary. For example, there can be two, four, six, eight, ten, twelve, fourteen, sixteen, or more electrodes  134 . As will be recognized, other numbers of electrodes  134  may also be used. 
     The electrodes of one or more leads  106  are typically disposed in, or separated by, a non-conductive, biocompatible material such as, for example, silicone, polyurethane, polyetheretherketone (“PEEK”), epoxy, and the like or combinations thereof. The leads  106  may be formed in the desired shape by any process including, for example, molding (including injection molding), casting, and the like. The non-conductive material typically extends from the distal end of the one or more leads  106  to the proximal end of each of the one or more leads  106  and forms a lead body  107 . 
     Terminals (e.g.,  210  in  FIG. 2A and 236  of  FIG. 2B ) are typically disposed at the proximal end of the one or more leads  106  of the electrical stimulation system  100  for connection to corresponding conductive contacts (e.g.,  214  in  FIG. 2A and 240  of  FIG. 2B ) in connectors (e.g.,  144  in  FIGS. 1-2A and 222 and 250  of  FIG. 2B ) disposed on, for example, the control module  102  (or to conductive contacts on a lead extension, an operating room cable, or an adaptor). Conductor wires (not shown) extend from the terminals (e.g.,  210  in  FIG. 2A and 236  of  FIG. 2B ) to the electrodes  134 . Typically, one or more electrodes  134  are electrically coupled to a terminal (e.g.,  210  in  FIG. 2A and 236  of  FIG. 2B ). In at least some embodiments, each terminal (e.g.,  210  in  FIG. 2A and 236  of  FIG. 2B ) is only connected to one electrode  134 . 
     The conductor wires may be embedded in the non-conductive material of the lead  106  or can be disposed in one or more lumens (not shown) extending along the lead  106 . In some embodiments, there is an individual lumen for each conductor wire. In other embodiments, two or more conductor wires may extend through a lumen. There may also be one or more lumens (not shown) that open at, or near, the proximal end of the lead  106 , for example, for inserting a stylet wire to facilitate placement of the lead  106  within a body of a patient. Additionally, there may also be one or more lumens (not shown) that open at, or near, the distal end of the lead  106 , for example, for infusion of drugs or medication into the site of implantation of the one or more leads  106 . In at least one embodiment, the one or more lumens may be flushed continually, or on a regular basis, with saline, epidural fluid, or the like. In at least some embodiments, the one or more lumens can be permanently or removably sealable at the distal end. 
     In at least some embodiments, leads are coupled to connectors disposed on control modules. In  FIG. 2A , a lead  208  is shown configured and arranged for insertion to the control module  102 . The connector  144  includes a connector housing  202 . The connector housing  202  defines at least one port  204  into which a proximal end  206  of a lead  208  with terminals  210  can be inserted, as shown by directional arrow  212 . The connector housing  202  also includes a plurality of conductive contacts  214  for each port  204 . When the lead  208  is inserted into the port  204 , the conductive contacts  214  can be aligned with the terminals  210  on the lead  208  to electrically couple the control module  102  to the electrodes ( 134  of  FIG. 1 ) disposed at a distal end of the lead  208 . Examples of connectors in control modules are found in, for example, U.S. Pat. Nos. 7,244,150 and 8,224,450, which are incorporated by reference. 
     In  FIG. 2B , a connector  222  is disposed on a lead extension  224 . The connector  222  is shown disposed at a distal end  226  of the lead extension  224 . The connector  222  includes a connector housing  228 . The connector housing  228  defines at least one port  230  into which a proximal end  232  of a lead  234  with terminals  236  can be inserted, as shown by directional arrow  238 . The connector housing  228  also includes a plurality of conductive contacts  240 . When the lead  234  is inserted into the port  230 , the conductive contacts  240  disposed in the connector housing  228  can be aligned with the terminals  236  on the lead  234  to electrically couple the lead extension  224  to the electrodes ( 134  of  FIG. 1 ) disposed at a distal end (not shown) of the lead  234 . 
     In at least some embodiments, the proximal end of a lead extension is similarly configured and arranged as a proximal end of a lead. The lead extension  224  may include a plurality of conductive wires (not shown) that electrically couple the conductive contacts  240  to a proximal end  248  of the lead extension  224  that is opposite to the distal end  226 . In at least some embodiments, the conductive wires disposed in the lead extension  224  can be electrically coupled to a plurality of terminals (not shown) disposed on the proximal end  248  of the lead extension  224 . In at least some embodiments, the proximal end  248  of the lead extension  224  is configured and arranged for insertion into a connector disposed in another lead extension. In other embodiments, the proximal end  248  of the lead extension  224  is configured and arranged for insertion into a connector disposed in a control module. As an example, in  FIG. 2B  the proximal end  248  of the lead extension  224  is inserted into a connector  250  disposed in a control module  252 . 
     Turning to  FIG. 3A , one potential target stimulation location is the dorsal root ganglia.  FIG. 3A  schematically illustrates a transverse cross-sectional view of a spinal cord  402  surrounded by dura  404 . The spinal cord  402  includes a plurality of levels from which spinal nerves  412   a  and  412   b  extend. In at least some spinal cord levels, the spinal nerves  412   a  and  412   b  extend bilaterally from the spinal cord  402 . In  FIG. 3A , the spinal nerves  412   a  and  412   b  attach to the spinal cord  402  via corresponding dorsal roots  414   a  and  414   b  and corresponding ventral (or anterior) roots  416   a  and  416   b . Typically, the dorsal roots  414   a  and  414   b  relay sensory information into the spinal cord  402  and the ventral roots  416   a  and  416   b  relay motor information outward from the spinal cord  402 . Dorsal root ganglia (“DRG”)  420   a  and  420   b  are nodules of cell bodies that are disposed along the dorsal roots  416   a  and  416   b  in proximity to the spinal cord  402 . 
       FIG. 3B  schematically illustrates a perspective view of a portion of the spinal cord  402  disposed along a portion of a vertebral column  430 . The vertebral column  430  includes a plurality of stacked vertebrae, such as vertebrae  432   a  and  432   b , and a plurality of DRGs  420   a  and  420   b  extending outwardly bilaterally from the spinal cord  402 . 
       FIG. 3C  schematically illustrates a top view of a portion of the spinal cord  402  and dura  404  disposed in a vertebral foramen  440  defined in the vertebra  432   b . The vertebrae  432  are stacked together and the vertebral foramina  440  of the vertebrae collectively form a spinal canal through which the spinal cord  402  extends. The space within the spinal canal between the dura  404  and the walls of the vertebral foramen  440  defines the epidural space  442 . Intervertebral foramina  446   a  and  446   b  defined bilaterally along sides of the vertebra  432   b  form openings through the vertebra  432   b  between the epidural space  442  and the environment external to the vertebra  432   b.    
       FIG. 3D  schematically illustrates a side view of two vertebrae  432   a  and  432   b  coupled to one another by a disc  444 . In  FIG. 3D , the intervertebral foramen  446   b  is shown defined between the vertebrae  432   a  and  432   b . The intervertebral foramen  446   b  provides an opening for one or more of the dorsal root  414   b , ventral root  416   b , and DRG  420   b  to extend outwardly from the spinal cord  402 . 
     To facilitate stimulation of the dorsal root ganglion (DRG), the distal end of the lead body can have a hook or coil shape to fit around at least a portion of the DRG. In at least some embodiments, the lead is implanted retrograde and perpendicular, or substantially perpendicular, to the DRG  420   a  and the dorsal root  414   a  extending from the DRG. In at least some embodiments, the portion of the lead extending from the hook-shaped or coil-shaped distal end is arranged to form an angle of at least 45°, 50°, 60°, 70°, 80°, or 85° with the dorsal root  414   a . In at least some embodiments, the hook-shaped or coil-shaped distal end of the lead body is isodiametric. In at least some embodiments, the hook-shaped or coil-shaped distal end of the lead body is also isodiametric with the remainder of the lead. 
       FIG. 4A  illustrates one embodiment of a lead  106  with a distal end  118  of the lead having a hook-shaped distal end to fit around the DRG  420   a . In at least some embodiments, the hook-shaped distal end extends around at least 40%, 50%, 60%, 70%, 75%, 80%, 90%, 95%, or 100% of the circumference of the DRG  420   a.    
       FIG. 4B  illustrates one embodiment of a lead  106  with a distal end  118  of the lead having a coil-shaped distal end to fit around a portion of the DRG  420   a . The coil-shaped distal end may include any number of full turns (360° turn) around the DRG  420   a  including, for example, at least one, two, or three full turns. The coil-shaped distal end may also include a partial turn (less than 360° turn). The turns of the coil-shaped distal end may be situated immediately adjacent to each other in a touching arrangement, as illustrated in  FIG. 4B , or the turns may be separated from each other or any combination thereof. 
       FIG. 5A  illustrates one embodiment of a distal end  118  of a lead  106  formed into a hook shape. A series of electrodes  134  are provided along the distal end  118  of the lead  106 . It will be recognized that the distal end  118  of lead  106  in this embodiment, as well as in those embodiments illustrated in  FIGS. 5B-8B , also corresponds to the distal end of the lead body of lead  106 . With respect to the designation of the distal end, the terms “lead” and “lead body” may be used interchangeably. 
     In this particular embodiment of  FIG. 5A , each of the electrodes  134  is a ring electrode that extends around the circumference of the lead at that position along the distal end of the lead body of lead  106 . Providing multiple electrodes allows the practitioner to select which electrodes are to be used to provide stimulation. The practitioner may use any combination of the electrodes and the selection of electrodes may change over time. 
       FIG. 5B  illustrates another embodiment of a distal end  118  of a lead  106  formed into a hook shape. A series of electrodes  134  are provided along the distal end  118  of the lead  106 . In this particular embodiment, each of the electrodes  134  is a segmented electrode that extends around only a portion of the circumference of the lead  106 . For example, a segmented electrode may extend around no more than 75%, 50%, 40%, 30%, 25%, or less of the circumference of the lead. In the illustrated embodiment, the segmented electrodes  134  are disposed on the interior surface of the hooked distal end  118  so that when the lead  106  is implanted with the hook around the DRG (for example, as illustrated in  FIG. 4A ), the segmented electrodes  134  are adjacent to the DRG. 
     One possible advantage of using segmented electrodes over ring electrodes is that the stimulation current from a segmented electrode is more directed instead of being distributed around the circumference of the lead which is generally the case for a ring electrode. This may be beneficial to more directly target the DRG and, at least in some cases, to reduce the inadvertent stimulation of other tissue, including other nerve or spinal cord tissue, in the neighborhood of the DRG. Inadvertent stimulation of the other tissue may result in side-effects which may be deleterious. 
       FIG. 5B  illustrates a single segmented electrode  134  at each position along the length of the distal end  118  of the lead  106 . It will be recognized, however, that sets of segmented electrodes can be provided at each position along the length of the lead with the member electrodes of each set distributed around the circumference of the lead at that position. For example, each set of segmented electrodes can include two, three, four, five, six, or more segmented electrodes distributed around the circumference of the lead at the same longitudinal position along the lead. Suitable examples of leads with sets of segmented electrodes can be found in, for example, U.S. Patent Applications Publication Nos. 2010/0268298; 2011/0005069; 2011/0078900; 2011/0130817; 2011/0130818; 2011/0238129; 2011/0313500; 2012/0016378; 2012/0046710; 2012/0165911; 2012/0197375; 2012/0203316; 2012/0203320; and 2012/0203321; and U.S. Provisional Patent Application Ser. No. 61/651,822, all of which are incorporated herein by reference. An advantage of using these sets of segmented electrodes is that the practitioner can select which electrodes from a set to use for stimulation. Moreover, if the distal end of the lead is bent or coiled by the practitioner, the practitioner may have less concern regarding whether the segmented electrodes are positioned properly on the hook or coil (e.g., on the interior surface of the hook or coil) because at least one segmented electrode of each is set is likely to be properly positioned. Markers may be provided on or within the lead to identify the relative orientation of the sets of segmented electrodes or the terminal at the proximal end of the lead that corresponds to a particular segmented electrode or both. Examples of suitable markers can be found in, for example, U.S. patent application Ser. Nos. 13/176,595 and 13/369,013 and U.S. Provisional Patent Application Ser. Nos. 61/591,046; and 61/617,922, all of which are incorporated herein by reference. 
     Other types of electrodes can be used including, for example, a tip electrode at the distal tip of the lead. It will be recognized that a lead may include any combination of segmented electrodes, ring electrodes, and other types of electrodes in any arrangement along the distal end of the lead. It will also be recognized that the lead may include one or more additional electrodes (for example, segmented electrodes or ring electrodes or any combination thereof) on the portion of the lead that does not form the hook or coil (e.g., the portion of the lead adjacent the hook-shaped or coil-shaped distal end of the lead.) These considerations regarding the electrodes and their arrangement, as described with respect to the embodiments illustrated in  FIGS. 5A and 5B , also apply to embodiments of a lead with a coiled distal end (see, for example,  FIG. 4B ), as well as the remainder of the lead embodiments described below including the embodiments illustrated in  FIGS. 6A-8B . 
     There are a variety of arrangements for providing a hook or coil shape to the distal end of the lead. In some embodiments, the lead is manufactured with the distal end in the hook or coil shape. In some embodiments, the practitioner may be able to modify the hook or coil shape provided during manufacture by, for example, bending or unbending the lead prior to implantation. In other embodiments, the hook or coil shape may be unmodifiable. 
     In other embodiments, the lead may incorporate a bendable shaping member within the distal end of the lead. The bendable shaping member is arranged so that a practitioner can bend the distal end of the lead into the desired hook or coil shape prior to, or during, the lead implantation procedure and the bendable shaping member will retain that shape thereafter. The bendable shaping member can be, for example, a metal or flexible plastic wire that retains its shape when bent. Typically, the bendable shaping member is not electrically coupled to the electrodes or terminals and, in at least some embodiments, the bendable shaping member is substantially thicker (for example, 1.5, 2, 3, 4, 5, or more times thicker) than the conductors coupling the electrodes to the terminals. For example, the bendable shaping member can be made of titanium, stainless steel, tungsten, a shape memory material such as Nitinol™, or the like. Preferably, the bendable shaping member is made of a material that is reversibly bendable (i.e., the bendable shaping member can be bent back to the original shape). The bendable shaping member permits formation of a hook or coil shape in the distal end of the lead by bending of the distal end of the lead into the hook or coil shape and the bendable shaping member is configured and arranged to retain the distal end of the lead in the hook or coil shape without external force being applied 
       FIGS. 6A and 6B  illustrate one embodiment of a distal end  118  of a lead  106  that has electrodes  134  and incorporates a bendable shaping member  602  within the lead.  FIG. 6A  illustrates the lead  106  in an unbent condition and  FIG. 6B  illustrates the lead  106  in one embodiment of a hook shape. It will be understood that the lead can be bent into other hook or coil shapes. The bendable shaping member  602  may be disposed anywhere within the lead including, but not limited to, embedded in a lead, disposed within one or more lumens of the lead, or disposed on a surface of the lead. The lead may include more than one bendable shaping member  602 . The bendable shaping member  602  may be disposed only at the distal end of the lead or may extend further along the lead; even to the proximal end of the lead in some embodiments. 
     In yet other embodiments, a removable guidewire or removable stylet may be used to bend the lead prior to, or during, the implantation procedure. The guidewire or stylet may be inserted into a lumen extending along at least a portion, including the distal end, of the lead prior to, or during, the implantation procedure for the lead. 
       FIGS. 7A and 7B  illustrate one embodiment of a distal end  118  of a lead  106  that has electrodes  134 .  FIG. 7A  illustrates the lead  106  in an unbent condition and without the guidewire or stylet inserted into the lead and  FIG. 7B  illustrates the lead  106  with the guidewire or stylet  704  inserted and causing the distal end of the lead to have a bent shape. It will be understood that the lead can be bent into other hook or coil shapes using a guidewire or stylet. In at least some embodiments, the guidewire or stylet is inserted into a lumen extending along at least a portion of the lead including, preferably, the distal end  118  of the lead. It will also be understood that more than one guidewire or stylet can be used and may be inserted into the same lumen or different lumens within the lead. 
       FIGS. 8A and 8B  illustrate an embodiment of a lead  106  and a guidewire or stylet  704  that incorporates an outer sheath  706  and an inner member  708 . Preferably, the outer sheath  706  and inner member  708  are slidably engaged to allow the outer sheath  706  to be retracted to expose a portion of the inner member  708 , or to allow the inner member to advance out of the outer sheath to expose the inner member, or to allow both retraction of the outer sheath and advancement of the inner member. In operation the outer sheath  706  of the guidewire or stylet  704  is arranged to maintain the guidewire or stylet  704  in a linear configuration, as illustrated in  FIG. 8A . This facilitates insertion of the lead  106  into the patient. The outer sheath  706  may then be partially, or fully, retracted, as illustrated in  FIG. 8B , (or advancement of the inner member out of the outer sheath) to expose at least a portion of the inner member  708 . The inner member  708  is arranged to bend to form the desired hook or coil shape. Examples of a guidewire or stylet with such an arrangement are described in U.S. Patent Application Publication No. 2009/0187222, which is incorporated herein by reference. 
     In some embodiments, a guidewire or stylet may remain in the lead after implantation to retain the bent or coiled shape of the distal end of the lead. In other embodiments, the guidewire or stylet may be removed after implantation and the distal end of the lead is arranged to maintain the bent or coil shape on its own or the practitioner fastens the lead to surrounding tissue (for example, using one or more sutures, staples, adhesives, lead anchors, or other fastening devices or any combination thereof) to retain the bent or coil shape or the surrounding tissue maintains the bent or coil shape of the distal end of the lead by preventing or reducing the likelihood of unbending or uncoiling or any combination of these mechanisms. 
     The leads described herein can be implanted using any suitable implantation method. A novel method for implanting the leads described herein is presented in U.S. Provisional Patent Application Ser. No. 61/651,815, incorporated herein by reference. 
       FIG. 9  is a schematic overview of one embodiment of components of an electrical stimulation system  900  including an electronic subassembly  910  disposed within a control module. It will be understood that the electrical stimulation system can include more, fewer, or different components and can have a variety of different configurations including those configurations disclosed in the stimulator references cited herein. 
     Some of the components (for example, power source  912 , antenna  918 , receiver  902 , and processor  904 ) of the electrical stimulation system can be positioned on one or more circuit boards or similar carriers within a sealed housing of an implantable pulse generator, if desired. Any power source  912  can be used including, for example, a battery such as a primary battery or a rechargeable battery. Examples of other power sources include super capacitors, nuclear or atomic batteries, mechanical resonators, infrared collectors, thermally-powered energy sources, flexural powered energy sources, bioenergy power sources, fuel cells, bioelectric cells, osmotic pressure pumps, and the like including the power sources described in U.S. Pat. No. 7,437,193, incorporated herein by reference. 
     As another alternative, power can be supplied by an external power source through inductive coupling via the optional antenna  918  or a secondary antenna. The external power source can be in a device that is mounted on the skin of the user or in a unit that is provided near the user on a permanent or periodic basis. 
     If the power source  912  is a rechargeable battery, the battery may be recharged using the optional antenna  918 , if desired. Power can be provided to the battery for recharging by inductively coupling the battery through the antenna to a recharging unit  916  external to the user. Examples of such arrangements can be found in the references identified above. 
     In one embodiment, electrical current is emitted by the electrodes  134  on the paddle or lead body to stimulate nerve fibers, muscle fibers, or other body tissues near the electrical stimulation system. A processor  904  is generally included to control the timing and electrical characteristics of the electrical stimulation system. For example, the processor  904  can, if desired, control one or more of the timing, frequency, strength, duration, and waveform of the pulses. In addition, the processor  904  can select which electrodes can be used to provide stimulation, if desired. In some embodiments, the processor  904  may select which electrode(s) are cathodes and which electrode(s) are anodes. In some embodiments, the processor  904  may be used to identify which electrodes provide the most useful stimulation of the desired tissue. 
     Any processor can be used and can be as simple as an electronic device that, for example, produces pulses at a regular interval or the processor can be capable of receiving and interpreting instructions from an external programming unit  908  that, for example, allows modification of pulse characteristics. In the illustrated embodiment, the processor  904  is coupled to a receiver  902  which, in turn, is coupled to the optional antenna  918 . This allows the processor  904  to receive instructions from an external source to, for example, direct the pulse characteristics and the selection of electrodes, if desired. 
     In one embodiment, the antenna  918  is capable of receiving signals (e.g., RF signals) from an external telemetry unit  906  which is programmed by a programming unit  908 . The programming unit  908  can be external to, or part of, the telemetry unit  906 . The telemetry unit  906  can be a device that is worn on the skin of the user or can be carried by the user and can have a form similar to a pager, cellular phone, or remote control, if desired. As another alternative, the telemetry unit  906  may not be worn or carried by the user but may only be available at a home station or at a clinician&#39;s office. The programming unit  908  can be any unit that can provide information to the telemetry unit  906  for transmission to the electrical stimulation system  900 . The programming unit  908  can be part of the telemetry unit  906  or can provide signals or information to the telemetry unit  906  via a wireless or wired connection. One example of a suitable programming unit is a computer operated by the user or clinician to send signals to the telemetry unit  906 . 
     The signals sent to the processor  904  via the antenna  918  and receiver  902  can be used to modify or otherwise direct the operation of the electrical stimulation system. For example, the signals may be used to modify the pulses of the electrical stimulation system such as modifying one or more of pulse duration, pulse frequency, pulse waveform, and pulse strength. The signals may also direct the electrical stimulation system  900  to cease operation, to start operation, to start charging the battery, or to stop charging the battery. In other embodiments, the stimulation system does not include an antenna  918  or receiver  902  and the processor  904  operates as programmed. 
     Optionally, the electrical stimulation system  900  may include a transmitter (not shown) coupled to the processor  904  and the antenna  918  for transmitting signals back to the telemetry unit  906  or another unit capable of receiving the signals. For example, the electrical stimulation system  900  may transmit signals indicating whether the electrical stimulation system  900  is operating properly or not or indicating when the battery needs to be charged or the level of charge remaining in the battery. The processor  904  may also be capable of transmitting information about the pulse characteristics so that a user or clinician can determine or verify the characteristics. 
     The above specification, examples and data provide a description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention also resides in the claims hereinafter appended.