Patent Publication Number: US-9887470-B2

Title: Torque lock anchor and methods and devices using the anchor

Description:
FIELD 
     The invention is directed to lead anchors for implantable devices, as well as the implantable devices themselves, and methods of manufacture and use of the lead anchors and implantable devices. The invention is also directed to lead anchors for implantable spinal cord stimulators, as well as the implantable spinal cord stimulators, and methods of manufacture and use of the lead anchors and the implantable spinal cord stimulators. 
     BACKGROUND 
     Spinal cord stimulation is a well accepted clinical method for reducing pain in certain populations of patients. Implantable stimulation devices have been developed to provide therapy for a variety of treatments. For example, implantable stimulation devices can be used to stimulate nerves, such as the spinal cord, muscles, or other tissue. An implantable stimulation device typically includes an implanted control module (with a pulse generator), a lead, and an array of stimulator electrodes. The stimulator electrodes are implanted 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. As an example, electrical pulses can be provided to the dorsal column fibers within the spinal cord to provide spinal cord stimulation. 
     The stimulator electrodes are coupled to the control module by the lead and the control module is implanted elsewhere in the body, for example, in a subcutaneous pocket. The lead is often anchored at one or more places in the body to prevent or reduce movement of the lead or stimulator electrodes within the body which could damage tissue, move the stimulator electrodes out of the desired position, or interrupt the connection between the stimulator electrodes and the control module. 
     Many conventional lead anchors do not sufficiently grip the lead to keep the lead in place. According to recent studies, lead migration occurs in approximately 13% of cases. Additional studies suggest that electrode migration may be the most common reason for failure to maintain long-term pain control with spinal cord stimulation. Other problems associated with lead migration include lead breakage, and loose connection. 
     Yet another problem associated with conventional lead anchors is that they are typically anchored at one or more places in the body to prevent or reduce movement of the lead by securing the anchor using sutures. These anchors are highly dependent on suturing technique and lead to variable holding forces. Depending on the physician, the suturing of the lead to the anchor may be too loose or too tight. Furthermore, the increased suturing may lead to an increased operation time with a greater risk of infection. 
     BRIEF SUMMARY 
     In one embodiment, a lead anchor includes a body defining a lead lumen having a first opening and a second opening through which a lead can pass. The body further defines a transverse lumen that intersects the lead lumen. The transverse lumen is configured and arranged to receive a fastener. An exterior member is disposed around at least a portion of the body. The exterior member is formed of a biocompatible material. The fastener anchors the lead to the body through the transverse lumen by deforming a portion of the lead. At least one suture element is defined by the exterior member and is configured and arranged for receiving a suture to suture the lead anchor to patient tissue. 
     In another embodiment, a lead anchor includes a body defining a lead lumen having a first opening and a second opening through which a lead can pass. The body further defines a fastening lumen. An exterior member is disposed around at least a portion of the body. The exterior member is formed of a biocompatible material. A pressure plate is movably disposed adjacent the body and a portion of the lead lumen. A fastener is coupled to the pressure plate through the fastening lumen. The fastener is configured and arranged to draw the pressure plate toward the body to contact a lead disposed in the lead lumen to hold the lead in the lead anchor. At least one suture element is defined by the exterior member and is configured and arranged for receiving a suture to suture the lead anchor to patient tissue. 
     In yet another embodiment, a method of implanting an implantable stimulation device includes implanting an electrode array near tissue to be stimulated. An anchor is disposed around a portion of the lead. The anchor includes a body defining a lead lumen having a first opening and a second opening through which a lead can pass. The body further defines a transverse lumen that intersects the lead lumen. An exterior member is disposed around at least a portion of the body. The exterior member is formed of a biocompatible material. A fastener anchors the lead to the body through the transverse lumen by deforming a portion of the lead. The transverse lumen is configured and arranged to receive the fastener. At least one suture element is formed by the exterior member and is configured and arranged for receiving a suture to suture the lead anchor to patient tissue. The fastener is tightened to secure the anchor to the lead. Sutures secure the anchor to the surrounding tissue. 
    
    
     
       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. 2  is a schematic view of another embodiment of an electrical stimulation system, according to the invention; 
         FIG. 3A  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. 3B  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. 4A  is a schematic cross-sectional view of one embodiment of a torque lead anchor with a pressure plate according to the invention; 
         FIG. 4B  is a schematic cross-sectional view of another embodiment of a torque lead anchor with a pressure plate according to the invention; 
         FIG. 4C  is a schematic side view of the torque lead anchor of  FIG. 4B , according to the invention; 
         FIG. 4D  is a schematic cross-sectional view of another embodiment of a torque lead anchor with a septum, according to the invention; 
         FIG. 5  is a schematic cross-sectional view of the torque lead anchor of  FIG. 4A  after a lead has been inserted in the lead anchor according to the invention; 
         FIG. 6  is a schematic cross-sectional view of one embodiment of a torque lead anchor with a sleeve according to the invention; 
         FIG. 7  is a schematic cross-sectional view of the torque lead anchor of  FIG. 6  after a lead has been inserted in the lead anchor according to the invention; 
         FIG. 8A  is a schematic perspective view of a portion of another embodiment of a lead anchor according to the invention; 
         FIG. 8B  is a schematic side view of the portion of the lead anchor of  FIG. 8A  according to the invention; 
         FIG. 8C  is a schematic front view of the portion of the lead anchor of  FIG. 8A  according to the invention; 
         FIG. 8D  is a schematic top view of the portion of the lead anchor of  FIG. 8A  according to the invention; 
         FIG. 9A  is a schematic perspective view of a portion of another embodiment of a lead anchor according to the invention; 
         FIG. 9B  is a schematic side view of the portion of the lead anchor of  FIG. 9A  according to the invention; 
         FIG. 9C  is a schematic front view of the portion of the lead anchor of  FIG. 9A  according to the invention; 
         FIG. 9D  is a schematic top view of the portion of the lead anchor of  FIG. 9A  according to the invention; 
         FIG. 10  is a schematic perspective view of the lead anchor of  FIG. 9A  attached to a lead according to the invention; 
         FIG. 11  is a schematic perspective view of the lead anchor of  FIG. 9A  and a tool according the invention; and 
         FIG. 12  is a schematic overview of one embodiment of components of an electrical 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 lead anchors used with elongate implantable devices such as spinal cord leads, cardiac pacing leads or catheters, implantable devices or systems containing the lead anchors, methods of use and manufacture of lead anchors and implantable devices. In addition, the invention is directed to lead anchors for implantable spinal cord stimulators, as well as the stimulators themselves and methods of use and manufacture of the lead anchors and spinal cord stimulators. 
     Suitable implantable electrical stimulation systems include, but are not limited to, an electrode lead (“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, paddle leads, and cuff 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; and 6,741,892; and U.S. patent applications Ser. Nos. 10/353,101, 10/503,281, 11/238,240; 11/319,291; 11/327,880; 11/375,638; 11/393,991; and 11/396,309, 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 , a paddle body  104 , and at least one lead body  106  coupling the control module  102  to the paddle body  104 . The paddle body  104  and the one or more lead bodies  106  form a lead. The paddle body  104  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  ( FIGS. 2 and 3A , see also  322  and  350  of  FIG. 3B ) into which the proximal end of the one or more lead bodies  106  can be plugged to make an electrical connection via connector contacts on the control module  102  and terminals (e.g.,  310  in  FIG. 3A and 336  of  FIG. 3B ) on each of the one or more lead bodies  106 . 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 electrical stimulation system references cited herein. For example, instead of a paddle body  104 , the electrodes  134  can be disposed in an array at or near the distal end of the lead body  106  forming a percutaneous lead, as illustrated in  FIG. 2 . A percutaneous lead may be isodiametric along the length of the lead. In addition, one or more lead extensions  312  (see  FIG. 3B ) can be disposed between the one or more lead bodies  106  and the control module  102  to extend the distance between the one or more lead bodies  106  and the control module  102  of the embodiments shown in  FIGS. 1 and 2 . 
     The electrical stimulation system or components of the electrical stimulation system, including one or more of the lead bodies  106 , the paddle body  104 , 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. 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 the paddle body  104  or one or more lead bodies  106  are typically disposed in, or separated by, a non-conductive, biocompatible material including, for example, silicone, polyurethane, polyetheretherketone, epoxy, and the like or combinations thereof. The paddle body  104  and one or more lead bodies  106  may be formed in the desired shape by any process including, for example, molding (including injection molding), casting, and the like. Electrodes and connecting wires can be disposed onto or within a paddle body either prior to or subsequent to a molding or casting process. The non-conductive material typically extends from the distal end of the lead to the proximal end of each of the one or more lead bodies  106 . The non-conductive, biocompatible material of the paddle body  104  and the one or more lead bodies  106  may be the same or different. The paddle body  104  and the one or more lead bodies  106  may be a unitary structure or can be formed as two separate structures that are permanently or detachably coupled together. 
     Terminals (e.g.,  310  in  FIG. 3A and 336  of  FIG. 3B ) are typically disposed at the proximal end of the one or more lead bodies  106  for connection to corresponding connector contacts (e.g.,  314  in  FIG. 3A and 340  of  FIG. 3B ) in connectors (e.g.,  144  in  FIGS. 1-3A and 322 and 350  of  FIG. 3B ) disposed on, for example, the control module  102  (or to other devices, such as connector contacts on a lead extension, an operating room cable, or an adaptor). Conductive wires (“conductors”) (not shown) extend from the terminals (e.g.,  310  in  FIG. 3A and 336  of  FIG. 3B ) to the electrodes  134 . Typically, one or more electrodes  134  are electrically coupled to a terminal (e.g.,  310  in  FIG. 3A and 336  of  FIG. 3B ). In some embodiments, each terminal (e.g.,  310  in  FIG. 3A and 336  of  FIG. 3B ) is only connected to one electrode  134 . The conductors may be embedded in the non-conductive material of the lead or can be disposed in one or more lumens (not shown) extending along the lead. In some embodiments, there is an individual lumen for each conductor. In other embodiments, two or more conductors 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 for example, for inserting a stylet rod to facilitate placement of the lead 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, for example, for infusion of drugs or medication into the site of implantation of the paddle body  104 . 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. 3A , a lead  308  is shown configured and arranged for insertion to the control module  102 . The connector  144  includes a connector housing  302 . The connector housing  302  defines at least one port  304  into which a proximal end  306  of a lead  308  with terminals  310  can be inserted, as shown by directional arrow  312 . The connector housing  302  also includes a plurality of connector contacts  314  for each port  304 . When the lead  308  is inserted into the port  304 , the connector contacts  314  can be aligned with the terminals  310  on the lead  308  to electrically couple the control module  102  to the electrodes ( 134  of  FIG. 1 ) disposed at a distal end of the lead  308 . Examples of connectors in control modules are found in, for example, U.S. Pat. No. 7,244,150 and U.S. patent application Ser. No. 11/532,844, which are incorporated by reference. 
     In  FIG. 3B , a connector  322  is disposed on a lead extension  324 . The connector  322  is shown disposed at a distal end  326  of the lead extension  324 . The connector  322  includes a connector housing  328 . The connector housing  328  defines at least one port  330  into which a proximal end  332  of a lead  334  with terminals  336  can be inserted, as shown by directional arrow  338 . The connector housing  328  also includes a plurality of connector contacts  340 . When the lead  334  is inserted into the port  330 , the connector contacts  340  disposed in the connector housing  328  can be aligned with the terminals  336  on the lead  334  to electrically couple the lead extension  324  to the electrodes ( 134  of  FIG. 1 ) disposed at a distal end (not shown) of the lead  334 . 
     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  324  may include a plurality of conductors (not shown) that electrically couple the connector contacts  340  to a proximal end  348  of the lead extension  324  that is opposite to the distal end  326 . In at least some embodiments, the conductors disposed in the lead extension  324  can be electrically coupled to a plurality of terminals (not shown) disposed on the proximal end  348  of the lead extension  324 . In at least some embodiments, the proximal end  348  of the lead extension  324  is configured and arranged for insertion into a connector disposed in another lead extension. In other embodiments, the proximal end  348  of the lead extension  324  is configured and arranged for insertion into a connector disposed in a control module. As an example, in  FIG. 3B  the proximal end  348  of the lead extension  324  is inserted into a connector  350  disposed in a control module  352 . 
     A lead anchor can be used in an implantable device, such as an implantable spinal cord stimulator, to anchor a lead connecting a control module to an electrode array. The lead anchor includes a fastener, which may be tightened to hold the lead. In at least some embodiments, the lead anchor applies gentle compression to the lead to hold the lead in place. 
       FIG. 4A  is a schematic cross-sectional view of one embodiment of a torque lead anchor  400 . As shown in  FIG. 4A , the torque lead anchor  400  includes a body  401  and an exterior member  410 . The body  401  may be made of a metal, such as titanium, nickel, aluminum, stainless steel, copper, gold, silver, platinum and alloys thereof or any other biocompatible metal, or a rigid plastic or polymer material. The exterior member  410  may be formed of any biocompatible material such as plastics and polymers including, but not limited to, silicone, polyvinyl chloride, fluoropolymers, polyurethane, polycarbonate, acrylic compounds, thermoplastic polyesters, polypropylene, low-density polyethylenes, and other thermoplastic elastomers. In some embodiments, the exterior member  410  is made of silicone. In some embodiments, the exterior member and the body are made of the same material. In some embodiments, the exterior member and the body are unitary. 
     Furthermore, it may be useful for any or all parts of the lead anchor to be made of a material that is radiopaque, so that it is visible under fluoroscopy or other forms of x-ray diagnosis. In some embodiments, the body or the exterior member is radiopaque so as to allow the lead anchor to be readily identified under fluoroscopy or other forms of x-ray diagnosis. The lead itself may also be radiopaque. 
     The body  401  contains a lead lumen  402  through which a lead  440  may pass. The lead lumen  402  has a first opening  403  and a second opening  404  for insertion of the lead. The lead lumen  402  may have a cross-section that is substantially circular as it extends from the first opening  403  to the second opening  404 . It is contemplated that the lead lumen  402  may also have a cross-section in the shape of a triangle, a square, an ovoid, or any other suitable shape that is large enough to house the lead  440 . In some embodiments the lead lumen  402  may be defined so that the lead  440  passes along a straight path through the center of the body  401 . Conversely the lead lumen  402  may be defined so that the lead  440  passes at an angled path through the body  401 . In some embodiments, the lead lumen  402  is defined as a curved path through the body  401 . In some embodiments, the body  401  contains more than one lead lumen so that the lead anchor  400  is able to house more than one lead. The opening may be a friction fit with the lead or can be large enough to allow the lead to pass through freely. In some embodiments, the lead lumen  402  is formed of a tapped and reamed through lumen. As seen in  FIG. 4D , the lead lumen  402  may also include ridges  450 , which may be concentric, for better engagement with the lead  440 . The lead lumen  402  may alternatively define an interior thread or another pattern for better engagement with the lead  440 . 
     The body  401  further defines a transverse lumen  405  for accepting a fastener  420 . The transverse lumen  405  may have a cross-section that is substantially circular. In other embodiments, the body  401  defines a transverse lumen  405  with a cross-section in the shape of a triangle, a square, an ovoid, or any other suitable shape that is capable of housing the fastener  420 . In some embodiments, the transverse lumen  405  is positioned perpendicular to the central axis of the lead lumen  402 . In other embodiments, the transverse lumen  405  may be defined so that the fastener  420  engages a lead  440  within the lead lumen  402  at a  15 ,  30 , or  45  degree angle or any other suitable angle with respect to the central axis of the lumen. In some embodiments, the transverse lumen  405  intersects the lead lumen  402  and extends through it so that a cross-shaped void is formed through the body  401 . In at least some embodiments, the transverse lumen  405  merges with the lead lumen  402  but does not extend through it, so that the cross-section of the body  401  defines a T-shaped bore. In at least some embodiments, the two lumens intersect with a sleeve or a plate disposed between the two (see, e.g.,  FIGS. 6 and 7 ). In embodiments with multiple lead lumens, the body  401  may define more than one transverse lumen for accepting a plurality of fasteners. Additionally, the body  401  may define a transverse lumen  405  having a thread, groove, crease, channel, duct or rib for facilitating or accepting the fastener  420 . 
     The fastener  420  may be, for example, a pin, clamp, latch, lug, nail, bolt, dowel, rod, rivet, screw or any combination thereof or any other suitable item for engaging and anchoring the lead. The fastener  420  may engage or couple to the lead anchor  400  by any method such as, for example, tightening, screwing or pushing. In some embodiments, the fastener  420  is a set screw with a thread to be received by the transverse lumen  405  of the body  401 . The set screw may be tightened through the use of a torque limiting tool  1100  (see  FIG. 11 ), which will be described in greater detail below. As the fastener  420  engages the body  401  through the transverse lumen  405 , it is brought closer to the lead lumen  402 . 
     In some embodiments, the fastener  420  engages a pressure plate  430  positioned within the transverse lumen  405 . As the fastener  420  is tightened, the pressure plate  430  is moved within the body  401  to obstruct the lead lumen  402 . When a lead  440  is placed within the lead lumen  402  and the fastener  420  is tightened, the pressure plate  430  closes down on the lead to keep it in place. As seen in  FIGS. 4A and 5 , in some embodiments, the cross section of the pressure plate  430  may be in the shape of a triangle. Alternatively, the cross-section of the pressure plate  430  may be in the shape of a circle, an ovoid, a rectangle, or any other suitable shape. In at least some embodiments, the lead is deformed when the pressure plate  430  is brought into position. In some embodiments, the deformation is slight (e.g., no more than 5% or 10% of the thickness of the lead). In other embodiments, the deformation is more significant (e.g., at least 10% or 25% of the thickness of the lead). The pressure plate  430  may be made of any suitable material, such as, for example, a metal such as titanium, nickel, aluminum, stainless steel, copper, gold, silver, platinum and alloys thereof, or a plastic, rubber or polymer such as polyurethane. In other embodiments (not shown), the fastener  420  directly contacts the lead  440  to lock it in position within the lead anchor  400 . 
     In at least some embodiments, surrounding the body  401 , an exterior member  410  may be formed of any suitable biocompatible material. The exterior member  410  may partially or completely surround the body  401 . In some embodiments, the exterior member  410  forms a skin around the body  401 . 
     As seen in  FIG. 4D , the exterior member  410  may also include a septum  451 . The septum  451  may comprise silicone. It will be understood that the septum  451  may also be formed of any elastic, biocompatible material including, but not limited to, those suitable for the exterior member  410 . In some embodiments, the septum  451  and the exterior member  410  are unitary and formed of the same material. In at least some other embodiments, the septum  451  is a separate member that is attached, glued, fixed, or otherwise coupled to the exterior member  410 . The septum  451  may be disposed on the exterior member  410  over the transverse lumen  405  to prevent the set screw from being disengaged from the torque lead anchor  400 . In some embodiments, the septum  451  includes a slit  452 , or opening to allow a tool to reach the fastener  420 . The slit  452  may be large enough to accept the tool, but too small for the fastener  420  to disengage from the torque lock anchor  400 . 
     In at least some embodiments, the exterior member  410  further defines at least one suture element  411 . The suture element  411  may be a groove, stub, ridge, eyelet, opening or bore or any other suitable arrangement for suturing the torque lead anchor  400  to the fascia, ligament or other tissue or body structure. The suture element  411  may be positioned anywhere around the circumference of the exterior member  410 . In some embodiments, a plurality of suture elements are disposed on the exterior member  410 . The exterior member  410  may also define an exterior transverse aperture  412  for receiving the fastener  420  and an exterior lead aperture  413  for receiving the lead. 
       FIG. 4B  is a schematic cross-sectional view of another embodiment of a torque lead anchor with a pressure plate. The torque lead anchor of  FIG. 4B  includes a body  401  similar to that of  FIG. 4A . The body defines a lead lumen  402  and a fastening lumen  421 . The torque lead anchor  400  also includes a pressure plate  430 . In some embodiments, as the fastener  420  is tightened, the pressure plate is drawn in contact with the lead (not shown) disposed within the lead lumen  402 . Thus, when the fastener  420  is tightened, the pressure plate  430  is drawn toward to the body  401 , the cross-sectional area of the lead lumen is reduced and the lead is secured. As an example, the fastener  420  and the interior of the fastening lumen  421  of the pressure plate  430  are threaded so that the tightening the fastener  420  draws the pressure plate  430  in contact with the lead.  FIG. 4C  is a schematic top view of the torque lead anchor  400  of  FIG. 4B . As can be appreciated from  FIG. 4C , the torque lead anchor  400  may be formed with a lower profile so that the lead anchor  400  does not excessively project from the surface of the tissue. 
       FIG. 5  is a schematic cross-sectional view of the torque lead anchor  400  of  FIG. 4A  after a lead  440  has been inserted in the lead anchor. As can be appreciated from  FIG. 5 , as the fastener  420  is tightened, the pressure plate  430  is brought in contact with the lead  440  within the lead lumen  402 . When the fastener  420  is completely tightened, the lead is locked in place within the lead anchor. In some embodiments, the lead  440  is partially deformed when locked in place. 
       FIG. 6  is a schematic cross-sectional view of another embodiment of a torque lead anchor  600  with a sleeve. As shown in  FIG. 6 , the torque lead anchor  600  comprises a body  601  and an exterior member  610 . The body  601  further contains a lead lumen  602  through which a lead may pass. The lead lumen  602  has a first opening  603  and a second opening  604  for insertion of the lead. The body  601  further defines a transverse lumen  605  for accepting a fastener  620 . Surrounding the body  601 , an exterior member  610  may be formed of a biocompatible material. The exterior member  610  further defines a suture element  611 . 
     As depicted in  FIG. 6 , in some embodiments, the fastener  620  engages a sleeve  630  positioned within the lead lumen  602 . The sleeve  630  may be a substantially hollow cylinder or sheath, and may be made of any suitable material, for example, a metal such as titanium, nickel, aluminum, stainless steel, copper, gold, silver, platinum and alloys thereof, or a plastic, rubber or polymer such as polyurethane. In other embodiments, the fastener  620  directly contacts the lead to lock it in position within the lead anchor. In some embodiments the sleeve  630  is disposed within the body  601  and receives the lead when the lead is passed through the first opening  603  of the lead lumen  602 . In another embodiment, the sleeve  630  is removable and is placed around the lead before it is inserted into the lead anchor  600 . In some embodiments, the sleeve is deformable when the fastener is tightened. The deformation of the sleeve may be slight (e.g., no more than 5% or 10% of the thickness of the sleeve) or more significant (e.g., at least 10% or 25% of the thickness of the sleeve). 
       FIG. 7  is a schematic cross-sectional view of the torque lead anchor  600  of  FIG. 6  after a lead  640  has been inserted in the lead anchor. As the fastener  620  is tightened, the sleeve  630  is deformed and obstructs the lead lumen. When a lead  640  is placed within the lead lumen and the fastener  620  is tightened, the sleeve  630  closes down on the lead to keep it in place. In at least some embodiments, the lead  640  is partially deformed when the sleeve  630  is acted upon by the fastener. 
       FIGS. 8A-8D  are schematic views of a portion of another embodiment of a lead anchor. As illustrated, the body  401  contains a lead lumen  402  for receiving a lead and a transverse lumen  405  for receiving a fastener  420 . The lead lumen  402  may have a radius smaller, equal to, or greater than the radius of the transverse lumen  405 . In at least some embodiments, the height of the body  401  may be between 0.200 and 0.600 inches (0.508 to 1.52 cm) or between 0.200 and 0.400 inches (0.508 to 1.02 cm). In at least some embodiments, the length of the body  401  may be between 0.200 and 0.400 inches (0.508 to 1.02 cm) or between 0.100 and 0.300 inches (0.254 to 0.762 cm). In at least some embodiments, the width of the body  401  may be between 0.100 and 0.300 inches (0.254 to 0.762 cm) or between 0.200 and 0.500 inches (0.508 to 1.27 cm). 
       FIGS. 9A-9D  are schematic views of a portion of one embodiment of a lead anchor. As can be appreciated from  FIG. 9A , the exterior member  410  contains an exterior transverse aperture  901  for receiving a fastener and an exterior lead aperture  902  for receiving a lead. Thus a fastener (not shown) is disposed in the exterior transverse aperture  901  and a lead (not shown) is inserted through the exterior lead aperture  902  and into the lead lumen of the body. As can be appreciated from  FIGS. 9A, 9B and 9C , the exterior member  410  may also contain suture eyelets  903  for suturing the lead anchor to the fascia or ligament. In at least some embodiments, the sutures are wrapped or tied around the anchor using the v-shaped portions of the exterior member. 
       FIG. 10  is a schematic perspective view of the lead anchor  400  of  FIG. 9A  attached to a lead  440 . Initially, a lead  440  is placed in position to achieve the desired parathesia at the chosen site of stimulation. In at least some embodiments, the lead is inserted through the exterior lead aperture and into the lead lumen  402  of the body  401 . The lead anchor  400  is slid along the length of the lead until it is in the desired position for anchoring to the ligament or fascia. In other embodiments, the body  401 , the exterior member  410 , or both may be formed of two complementary members that, when joined around a lead  440 , form the lead anchor. Thus, no sliding of the lead is necessary. Each of the two complementary members maybe joined together through clasps, buckles, fasteners or by any other suitable arrangement. After the lead has been positioned as desired a fastener is tightened so that the lead  440  is locked in place within the lead anchor  400 . 
       FIG. 11  is a schematic perspective view of the lead anchor  400  of  FIG. 9A  and a tool  1100 . The tool  1100  may be a screwdriver, wrench, pliers, or drill or any other suitable tool useful for setting, fixing, screwing, tightening, fastening or fitting a fastener with the lead anchor  400 . In at least some embodiments, the tool  1100  is a torque limiting tool set to a certain threshold above which it will no longer tighten the fastener. With this method, over-tightening of the fastener is avoided and the lead can be protected from possible damage due to overtightening the fastener. For example, the torque limiting tool may be configured to limit the number of revolutions or the depth to which a fastener may be advanced. 
       FIG. 12  is a schematic overview of one embodiment of components of an electrical stimulation system  1200  including an electronic subassembly  1210  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  1212 , antenna  1218 , receiver  1202 , and processor  1204 ) 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  1212  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. Patent Application Publication No. 2004/0059392, incorporated herein by reference. 
     As another alternative, power can be supplied by an external power source through inductive coupling via the optional antenna  1218  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  1212  is a rechargeable battery, the battery may be recharged using the optional antenna  1218 , if desired. Power can be provided to the battery for recharging by inductively coupling the battery through the antenna to a recharging unit  1016  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  1204  is generally included to control the timing and electrical characteristics of the electrical stimulation system. For example, the processor  1204  can, if desired, control one or more of the timing, frequency, strength, duration, and waveform of the pulses. In addition, the processor  1204  can select which electrodes can be used to provide stimulation, if desired. In some embodiments, the processor  1204  may select which electrode(s) are cathodes and which electrode(s) are anodes. In some embodiments, the processor  1204  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  1208  that, for example, allows modification of pulse characteristics. In the illustrated embodiment, the processor  1204  is coupled to a receiver  1202  which, in turn, is coupled to the optional antenna  1218 . This allows the processor  1204  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  1218  is capable of receiving signals (e.g., RF signals) from an external telemetry unit  1206  which is programmed by a programming unit  1208 . The programming unit  1208  can be external to, or part of, the telemetry unit  1206 . The telemetry unit  1206  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  1206  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  1208  can be any unit that can provide information to the telemetry unit  1206  for transmission to the electrical stimulation system  1200 . The programming unit  1208  can be part of the telemetry unit  1206  or can provide signals or information to the telemetry unit  1206  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  1206 . 
     The signals sent to the processor  1204  via the antenna  1218  and receiver  1202  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  1200  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  1218  or receiver  1202  and the processor  1204  operates as programmed. 
     Optionally, the electrical stimulation system  1200  may include a transmitter (not shown) coupled to the processor  1204  and the antenna  1218  for transmitting signals back to the telemetry unit  1206  or another unit capable of receiving the signals. For example, the electrical stimulation system  1200  may transmit signals indicating whether the electrical stimulation system  1200  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  1204  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.