Abstract:
A connector assembly includes a lead or a lead extension, a connector, and a retention assembly disposed in the connector. The connector includes a connector housing defining a port at a distal end of the connector, and a plurality of connector contacts disposed in the connector housing. The port is configured and arranged for receiving a proximal end of the lead or the lead extension. The connector contacts are configured and arranged to couple to at least one terminal disposed on the proximal end of the lead or the lead extension. The retention assembly includes a retention mechanism that can be engaged and reversibly disengaged without the use of tools beyond conventional operating-room surgical instruments.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a utility patent application based on a previously filed U.S. Provisional Patent Application, Ser. No. 61/088,301 filed on Aug. 12, 2008, the benefit of which is hereby claimed under 35 U.S.C. §119(e) and incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    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 systems having leads or lead extensions secured to connectors by retention assemblies, as well as methods of making and using retention assemblies, leads, lead extensions, and electrical stimulation systems. 
       BACKGROUND 
       [0003]    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. Deep brain stimulation has also been useful for treating refractory chronic pain syndromes and has been applied to treat movement disorders and epilepsy. 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. Moreover, electrical stimulation systems can be implanted subcutaneously to stimulate subcutaneous tissue including subcutaneous nerves such as the occipital nerve. 
         [0004]    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 
       [0005]    In one embodiment, a connector assembly includes a lead or a lead extension, a connector, and a retention assembly disposed in the connector. The lead or the lead extension includes a proximal end and an outer covering. The lead or the lead extension also includes a plurality of terminals disposed at the proximal end of the lead or the lead extension. The connector includes a proximal end, a distal end, and a longitudinal length and is configured and arranged to receive the lead or the lead extension. The connector also includes a connector housing defining a port at the distal end of the connector, and a plurality of connector contacts disposed in the connector housing. The port is configured and arranged for receiving the proximal end of the lead or the lead extension. The connector contacts are configured and arranged to couple to at least one of the plurality of terminals disposed on the proximal end of the lead or the lead extension. The retention assembly is configured and arranged for removably securing the lead or the lead extension to the connector. The retention assembly includes a threaded member disposed on either i) the connector or ii) the lead or the lead extension that is configured and arranged to mate with a threaded aperture defined in the other of i) the connector or ii) the lead or the lead extension. 
         [0006]    In another embodiment, a connector assembly includes a lead or a lead extension and a connector. The lead or the lead assembly includes a proximal end and an outer covering. The lead or the lead extension also includes a plurality of terminals disposed at the proximal end of the lead or the lead extension and an annular groove disposed in the proximal end of the lead or the lead extension. The connector includes a proximal end, a distal end, and a longitudinal length and is configured and arranged to receive the lead or the lead extension. The connector also includes a connector housing, a plurality of connector contacts, and a retention assembly. The connector housing defines a port at the distal end of the connector. The port is configured and arranged for receiving the proximal end of the lead or the lead extension. The plurality of connector contacts are disposed in the connector housing and are configured and arranged to couple to at least one of the plurality of terminals disposed on the proximal end of the lead or the lead extension. The retention assembly is configured and arranged for removably securing the lead or the lead extension to the connector. The retention assembly includes a coupling member disposed on the connector. The coupling member is configured and arranged to couple with the annular groove disposed in the lead or the lead extension. 
         [0007]    In yet another embodiment, a connector assembly includes a lead or a lead extension and a connector. The lead or the lead extension includes a proximal end and an outer covering. The lead or the lead extension also includes a plurality of terminals disposed at the proximal end of the lead or the lead extension. The connector includes a proximal end, a distal end, and a longitudinal length and is configured and arranged to receive the lead or the lead extension. The connector also includes a connector housing, a plurality of connector contacts, and a retention assembly. The connector housing defines a port at the distal end of the connector. The port is configured and arranged for receiving the proximal end of the lead or the lead extension. The plurality of connector contacts are disposed in the connector housing. The connector contacts are configured and arranged to couple to at least one of the plurality of terminals disposed on the proximal end of the lead or the lead extension. The retention assembly is disposed in the connector. The retention assembly includes at least one retention member. The retention assembly is configured and arranged for removably securing the lead or the lead extension to the connector by bending or pivoting the at least one retention member to press against the lead or the lead extension. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    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. 
           [0009]    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: 
           [0010]      FIG. 1  is a schematic view of one embodiment of an electrical stimulation system, according to the invention; 
           [0011]      FIG. 2  is a schematic view of another embodiment of an electrical stimulation system, according to the invention; 
           [0012]      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; 
           [0013]      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; 
           [0014]      FIG. 4  is a schematic longitudinal cross-sectional view of one embodiment of a connector that includes a threaded post and a proximal end of a lead or a lead extension defining a threaded aperture configured and arranged to mate with the threaded post, according to the invention; 
           [0015]      FIG. 5  is a schematic longitudinal cross-sectional view of one embodiment of a connector that includes a threaded collar and a split collet and a proximal end of a lead or a lead extension that includes a retention sleeve, the proximal end of the lead or the lead extension secured in the connector by the split collet pressing against the retention sleeve, according to the invention; 
           [0016]      FIG. 6  is a schematic side view of a one embodiments of a connector that includes a locking lever shown in two positions, with a portion of the connector shown as a longitudinal cross-sectional view of the connector with a proximal end of a lead or a lead extension that includes a retention sleeve inserted into the connector, the proximal end of the lead or the lead extension secured in the connector by the locking lever pressing against the body of the lead or the lead extension distal to the retention sleeve, according to the invention; 
           [0017]      FIG. 7A  is a schematic perspective view of a connector that includes a split shell connector housing in an open position and a proximal end of a lead or a lead extension configured and arranged for insertion into the split shell connector housing, according to the invention; 
           [0018]      FIG. 7B  is a schematic perspective view of one embodiment of the proximal end of the lead or the lead extension shown in  FIG. 7A  inserted into the connector shown in  FIG. 7A , the connector maintained in a closed position by snap-fit closures, according to the invention; 
           [0019]      FIG. 7C  is a schematic perspective view of one embodiment of the proximal end of the lead or the lead extension shown in  FIG. 7A  inserted into the connector shown in  FIG. 7A , the connector maintained in a closed position by a cylindrical sleeve disposed over the connector, according to the invention; 
           [0020]      FIG. 8A  is a schematic perspective view of one embodiment of a retention assembly that includes a clip configured and arranged to be mounted to a connector and a proximal end of a lead or a lead extension configured and arranged for insertion into the clip, according to the invention; 
           [0021]      FIG. 8B  is a schematic perspective view of one embodiment of the proximal end of the lead or the lead extension shown in  FIG. 8A  secured in the clip shown in  FIG. 8A , according to the invention; 
           [0022]      FIG. 9A  is a schematic perspective view of one embodiment of a retention assembly that includes a sliding lock configured and arranged to be mounted to a connector, the sliding lock in a retaining position, and a proximal end of a lead or a lead extension configured and arranged for insertion into the sliding lock, according to the invention; 
           [0023]      FIG. 9B  is a schematic perspective view of one embodiment of the sliding lock shown in  FIG. 9A  in an open position and a proximal end of a lead or a lead extension configured and arranged for insertion into the sliding lock, according to the invention; 
           [0024]      FIG. 9C  is a schematic perspective view of one embodiment of the proximal end of the lead or the lead extension shown in  FIGS. 9A and 9B  secured in the sliding lock shown in  FIG. 9A  in a retaining position, according to the invention; 
           [0025]      FIG. 9D  is a schematic perspective, longitudinal cross-sectional view of one embodiment of the proximal end of the lead or the lead extension shown in  FIGS. 9A and 9B  secured in the sliding lock shown in  FIGS. 9A and 9B  placed in a retaining position, according to the invention; and 
           [0026]      FIG. 10  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 
       [0027]    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 systems having leads or lead extensions secured to connectors by retention assemblies, as well as methods of making and using retention assemblies, leads, lead extensions, and electrical stimulation systems. 
         [0028]    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 Application Publications Nos. 2003/0114905; 2005/0165465; 2007/0150036; 2007/0161294; 2007/0219595; 2007/0239243; and 2007/0150007; U.S. patent application Ser. No. 11/238,240; all of which are incorporated by reference. 
         [0029]      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 conductive 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 . 
         [0030]    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. 
         [0031]    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. 
         [0032]    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 (“PEEK”), 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. 
         [0033]    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 conductive 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 conductive contacts on a lead extension, an operating room cable, or an adaptor). Conductive wires (not shown) extend from the terminals (e.g.,  310  in  FIG. 3A and 336  of  FIG. 3B ) to the electrodes  134 . In some embodiments, each terminal (e.g.,  310  in  FIG. 3A and 336  of  FIG. 3B ) is connected to one electrode  134 . In other embodiments, each terminal (e.g.,  310  in  FIG. 3A and 336  of  FIG. 3B ) is connected to a plurality of electrodes  134 . The conductive wires 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 conductive wire. In other embodiments, two or more conductive 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, 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. 
         [0034]    Retention assemblies are sometimes used to secure two or more coupled components of an electrical stimulation system. For example, a retention assembly may be used to secure a lead or lead extension to a connector disposed on a control module (as shown in  FIG. 3A ) or a lead extension (as shown in  FIG. 3B ). Leads or lead extensions may also be secured to connectors disposed on other devices, such as an operating room cable or an adaptor. In  FIG. 3A , the connector  144  is shown disposed on 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 or a lead extension  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  and a fastener aperture  316  for each port  304 . When the lead or the lead extension  308  is inserted into the port  304 , the connector contacts  314  can be aligned with the terminals  310  on the lead or the lead extension  308  to electrically couple the control module  102  to the electrodes ( 134  of  FIG. 1 ) electrically coupled to the lead or the lead extension  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. 
         [0035]    In at least some embodiments, a retention assembly may be used to secure a lead or a lead extension to a connector disposed on a control module. In some embodiments, a retention assembly includes a fastener and a fastener aperture configured and arranged to mate with the fastener. For example, a fastener  318  can be mated with the fastener aperture  316  to form a retention assembly  320 . The retention assembly  320  can be used to secure the lead or the lead extension  308  to the control module  102 . Fasteners and fastener apertures can be made from many different metallic or ceramic materials suitable for implantation. In  FIG. 3A , the fastener  318  is shown as a set screw and the fastener aperture  318  is shown as a threaded aperture configured and arranged to mate with the set screw. In at least some embodiments, the fastener  318  is inserted into the fastener aperture  316  and tightened against a retention sleeve  321  disposed on the lead or the lead extension  308  distal to the terminals  310 . The retention sleeve  321  can be formed using any rigid, biocompatible material. Examples of suitable materials include metals, alloys, rigid polymers, rigid carbon, and the like, as well as combinations thereof. The fastener aperture  316  may be positioned in many different locations along the length of connector  144 . In  FIG. 3A  and in subsequent figures, fastener apertures are shown disposed in proximity to the port  304  of the connector for clarity of illustration. Accordingly, the retention sleeve  321  is shown distal to the terminals  310  to align with the fastener aperture  316  when the proximal end  306  of the lead or the lead extension  308  is inserted into the port  304  of the connector  144 . 
         [0036]    In at least some embodiments, a retention assembly may be used to secure a lead or a lead extension to a connector disposed on a lead extension. 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 or a lead extension  334  with terminals  336  can be inserted, as shown by directional arrow  338 . The connector housing  328  also includes a plurality of conductive contacts  340  and a fastener aperture  342 . When the lead or the lead extension  334  is inserted into the port  330 , the conductive contacts  340  disposed in the connector housing  328  can be aligned with the terminals  336  on the lead or the lead extension  334  to electrically couple the lead extension  324  to the electrodes ( 134  of  FIG. 1 ) electrically coupled to the lead or the lead extension  334 . A fastener  344  can be mated with the fastener aperture  342  to form a fastener assembly  346 , which can be used to secure the lead or the lead extension  334  to the connector  322  disposed at the distal end  326  of the lead extension  324 . 
         [0037]    In at least some embodiments, the proximal end of a lead extension is similarly configured and arranged to a proximal end of a lead. The lead extension  324  may include a plurality of conductive wires (not shown) that electrically couple the conductive 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 conductive wires 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. For 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 fastener  354  is disposed in a fastener aperture  356  and tightened against a retention sleeve  358  disposed on the lead extension  324  to secure the proximal end  348  of the lead extension  324  to the control module  348 . Note that, when a lead or a lead extension includes two or more proximal ends, each proximal end can be inserted into one of a plurality of ports defined in a connector, with each port including a plurality of conductive contacts, and with each proximal end of the lead or the lead extension secured to the connector by one or more of the retention assemblies. 
         [0038]    When a set screw and a corresponding threaded aperture are used to secure a lead or a lead extension to a connector, a tool, such as an Allen wrench, is sometimes used to tighten the set screw against a retention sleeve disposed on the lead or the lead extension, as shown in  FIGS. 3A and 3B . Using a wrench, such as an Allen wrench, to tighten the set screw against the inserted lead or the lead extension can sometimes be burdensome and add additional time to a medical procedure. Consequently, it may be an advantage to utilize one or more retention assemblies that can be used to secure a lead or a lead extension to a connector without needing a wrench to facilitate the securement. It may especially be an advantage when the connector is disposed on a distal end of a lead extension. It may also be an advantage to utilize one or more retention assemblies to secure a lead or a lead extension to a connector without a wrench if an explant is to be performed and two or more components are to be separated and no appropriate wrench is readily available. 
         [0039]    In at least some embodiments, a lead or a lead extension may be secured to a connector using a threaded member that mates with a threaded aperture. In at least some embodiments, a lead or a lead extension may be secured to a connector by a retention assembly incorporating a “screw-on” type of connection.  FIG. 4  is a schematic longitudinal cross-sectional view of one embodiment of a connector  402  and a proximal end of a lead or a lead extension  404 . The connector  402  has a proximal end  406  and a distal end  408  and includes a connector housing  410 . The connector housing  410  defines a port  412  extending from the distal end  408  of the connector  402  and includes a plurality of connector contacts, such as connector contact  414 , disposed in the connector housing  410 . The connector housing  410  also includes a threaded post  416  disposed at the proximal end  406  of the connector  402 . 
         [0040]    The proximal end of the lead or the lead extension  404  includes a plurality of terminals, such as terminal  418 , and defines a threaded aperture  420  proximal to the terminals that is configured and arranged to mate with the threaded post  416  when the proximal end of the lead or the lead extension  404  is inserted into the connector housing  410 . The threaded post  416  can be mated with the threaded aperture  420  to form a retention assembly  422 . In at least some embodiments, the threaded aperture  410  can be screwed onto the threaded post  416  without the need for a supplementary tool. In at least some embodiments, the proximal end of the lead or the lead extension  404  also defines at least one lumen  424  extending along a longitudinal length of the proximal end of the lead or the lead extension  404 . In at least one embodiment, the threaded aperture  420  is continuous with the at least one lumen  424 . In at least some embodiments, the threaded post  416  is disposed on the proximal end of the lead or the lead extension and the threaded aperture  420  is defined in the connector  402 . 
         [0041]    In at least some embodiments, a lead or a lead extension may be secured to a connector by a retention assembly incorporating a “pin vise” type of connection.  FIG. 5  is a schematic longitudinal cross-sectional view of one embodiment of a connector  502  and a proximal end of a lead or a lead extension  504  inserted into the connector  502 . The connector  502  has a proximal end  506  and a distal end  508  and includes a connector housing  510 . The connector housing  510  includes a retention assembly  512 . The retention assembly  512  includes a split collet  514  and a threaded collar  516 . The split collet  514  includes one or more gripping members  518  disposed at the distal end  508  of the connector  502 . In at least some embodiments, the one or more gripping members  518  serve as retention members. The threaded collar  516  is disposed over at least a portion of the split collet  514 . 
         [0042]    In at least some embodiments, the proximal end of the lead or the lead extension  504  includes a retention sleeve  520  disposed on the proximal end of the lead or the lead extension  504  distal to a plurality of terminals, such as terminal  522 . When the proximal end of the lead or the lead extension  504  is inserted into the connector  502 , the threaded collar  516  can be screwed in a proximal direction against the split collet  514 . As the threaded collar  516  moves proximally down a longitudinal length of the connector  502 , the one or more gripping members  518  are deformed inward, eventually pressing against the inserted proximal end of the lead or the lead extension  504  to secure the inserted proximal end of the lead or the lead extension  504  in the connector  502 . In some embodiments, the one or more gripping members  518  press against an outer covering of the proximal end of the lead or the lead extension  504  distal to the plurality of terminals. In other embodiments, the one or more gripping members  518  press against an outer covering of the proximal end of the lead or the lead extension  504  proximal to the plurality of terminals. In at least some embodiments, the one or more gripping members  518  press against the retention sleeve  520  disposed on the proximal end of the lead or the lead extension  504 , as shown in  FIG. 5 . In at least some embodiments, the retention sleeve  520  is a rigid portion of the lead, or a rigid element, such as a metal ring disposed on the lead, which may be used to provide a bearing for a fastener to tighten against. In at least some embodiments, the retention sleeve  520  is flush with an outer diameter of the lead or the lead extension  504 . 
         [0043]    In at least some embodiments, a lead or a lead extension may be secured to a connector by a retention assembly incorporating a “lockable latch” type of connection.  FIG. 6  is a schematic side view of one embodiment of a connector  602  and a proximal end of a lead or a lead extension  604  inserted in the connector  602 . In  FIG. 6 , a portion of the connector  602  is removed to show a longitudinal cross-sectional view of a portion of the connector  602  and the inserted proximal end of the lead or the lead extension  604 . The connector  602  has a proximal end  606  and a distal end  608  and includes a connector housing  610 . The connector housing  610  includes a retention assembly  612  which, in turn, includes one or more lockable latches  614  which serve as one or more retention members. 
         [0044]    The one or more lockable latches  614  each include a hinged locking member  616  configured and arranged to pivot between an open position and a closed position. When each hinged locking member  616  is in an open position, as shown in  FIG. 6  by the dashed representation  618  of the hinged locking member  616 , the proximal end of the lead or the lead extension  604  can be inserted into, or removed from, the connector housing  610 . The hinged locking member  616  can be pivoted to a closed position, as shown in  FIG. 6  by the solid representation of the hinged locking member  616 , to lock against a catch  620 . When the proximal end of the lead or the lead extension  604  is inserted into the connector housing  610  and the hinged locking member  616  is locked against the catch  620 , protrusions  622  disposed on the hinged locking member  616  and the catch  620  press against the inserted proximal end of the lead or the lead extension  604  to secure the lead or the lead extension  604  in the connector housing  610 . In some embodiments, the protrusions  622  press against an outer surface of the proximal end of the lead or the lead extension  604  distal to the plurality of terminals. In some embodiments, the protrusions  622  press against an outer covering of the proximal end of the lead or the lead extension  604  distal to a retention sleeve  624  disposed on the proximal end of the lead or the lead extension  604 , as shown in  FIG. 6 . In at least one embodiment, each of the one or more lockable latches can be pivoted from an open position to a closed position, and vice versa, by hand without the use of a supplementary tool. In at least some embodiments, one or more tools, such as forceps, can be used to pivot one or more of the lockable latches between an open and a closed position. In at least some embodiments, the locking member slides between an open and closed position. In some embodiments, the protrusions  622  are disposed on both the locking member  616  and the catch  620 . In other embodiments, the protrusions are disposed on either the locking member  616  or the catch  620 . In at least some embodiments, a plurality of protrusions  620  are disposed on either or both the locking member  616  or the catch  620 . 
         [0045]    In at least some embodiments, a lead or a lead extension may be secured to a connector by a retention assembly incorporating a “split shell” type of connection.  FIG. 7A  is a schematic perspective view of one embodiment of a connector  702  and a proximal end of a lead or a lead extension  704 . The connector  702  has a proximal end  706 , a distal end  708 , and a longitudinal length, shown in  FIG. 7A  as a two-headed arrow  710 . The connector  702  includes a connector housing  712 . In at least some embodiments, the connector housing  712  is openable approximately longitudinally along the longitudinal length  710  of the connector housing  712  and includes a first piece  714  and a second piece  716 . The first piece  714  including a first pocket  718  and the second piece  716  including a second pocket  720 . The first pocket  718  including a plurality of connector contacts, such as connector contact  722 . In at least some embodiments, the second pocket  720  also includes a plurality of connector contacts, such as connector contact  724 . In  FIG. 7A , the connector housing  712  is shown in an open position. In at least some embodiments, the connector housing  712  can be placed in a closed position by pivoting the second piece  716 , as shown by directional arrow  726 , to form a retention assembly  728 . In some embodiments, the first piece  714  and the second piece  716  are coupled to one another by one or more pivots. For example, as shown in  FIG. 7A , one or more hinges may couple the first piece  714  to the second piece  716 . In other embodiments, the first piece  714  and the second piece  716  may be separate pieces that couple together by one or more fasteners. Many different types of fasteners may be used, including, adhesive, one or more snaps, one or more clasps, and the like or combinations thereof. For example, the first piece  714  and the second piece  716  may snap together. In at least some embodiments, the retention assembly may employ both one or more pivots and one or more fasteners. 
         [0046]    The proximal end of the lead or the lead extension  704  includes a plurality of terminals, such as terminal  730 , disposed at the proximal end of the lead or the lead extension  704 . The proximal end of the lead or the lead extension  704  also includes an annular groove  732  proximal to the plurality of terminals and a proximal flange  734  disposed proximal to the annular groove  732 . The annular groove  732  may have many different widths and depths. Additionally, the annular groove  732  may have many different longitudinal cross-sectional shapes. For example, the annular groove  732  may have a longitudinal cross-sectional shape that is U-shaped, V-shaped, hemispherical-shaped, W-shaped, rectangular-shaped, and the like. In at least some embodiments, the annular groove  732  is positioned proximal to the plurality of terminals. In at least some embodiments, the annular groove  732  is positioned in a retention sleeve, such as the retention sleeve ( 321  in  FIG. 3A ,  520  in  FIG. 5 , and  624  in  FIG. 6 ). 
         [0047]    In at least some embodiments, the first pocket  718  and the second pocket  720  are configured and arranged to collectively approximate the shape of the proximal end of the lead or the lead extension  704  when the proximal end of the lead or the lead extension  704  is inserted into the connector  702  and the connector housing  712  is pivoted to a closed position. In at least some embodiments, the shape of the annular groove  732  facilitates securement of the inserted lead or the lead extension  704  in the connector housing  712  when the connector housing  712  is in a closed position. In at least some embodiments, the shape of the annular groove  732  and the proximal flange  734  facilitate securement of the inserted lead or the lead extension  704  in the connector housing  712  when the connector housing  712  is in a closed position. 
         [0048]    In some embodiments, the connector housing  712  is maintained in a closed position by one or more closures, such as snap-fit closures, disposed on the first piece  714  and the second piece  716 .  FIG. 7B  is a schematic perspective view of one embodiment of the proximal end of the lead or the lead extension  704  inserted into the connector housing  712  and the connector housing  712  maintained in a closed position by snap-fit closures  736  and  738 . In other embodiments, the connector housing  712  is maintained in a closed position by a cylindrical sleeve disposed over at least a portion of the connector housing  712 .  FIG. 7C  is a schematic perspective view of one embodiment of the proximal end of the lead or the lead extension  704  inserted into the connector housing  712  and the connector housing  712  maintained in a closed position by a cylindrical sleeve  740  disposed over at least a portion of the connector housing  712 . 
         [0049]    In at least some embodiments, a lead or a lead extension may be secured to a connector by a retention assembly incorporating a “deformable member” type of connection.  FIG. 8A  is a schematic perspective view of one embodiment of a retention assembly  800 . The retention system  800  includes a clip  802  configured and arranged to be mounted to a proximal end of a connector (see e.g.,  144  of  FIGS. 2 and 3A , and  322  and  350  of  FIG. 3B ) and a proximal end of a lead or a lead extension  804  configured and arranged for insertion into the clip  802 . In  FIGS. 8A-8B , the connector has been omitted for clarity of illustration. 
         [0050]    In at least some embodiments, the clip  802  has a proximal end  806 , a distal end  808 , and a longitudinal length  810 . The clip  802  includes a base  812  at the proximal end  806  and one or more deformable circumferential members  814  forming an elongated opening, such as an oval-shaped opening, at the distal end  808 . In at least some embodiments, the clip  802  also defines at least one window  816  along the longitudinal length  810  of the clip  802 . The elongated opening is formed by the one or more deformable circumferential members  814  at the distal end  808 . The elongated opening includes a major axis  818  and a minor axis  820 . The proximal end of the lead or the lead extension  804  includes a plurality of terminals, such as terminal  822 , disposed at the proximal end of the lead or the lead extension  804 . The proximal end of the lead or the lead extension  804  also includes an annular groove  824  proximal to the plurality of terminals and a proximal flange  826  disposed proximal to the annular groove  824 . 
         [0051]    In at least some embodiments, the clip  802  is configured and arranged to receive the proximal end of the lead or the lead extension  804  through the elongated opening formed by the one or more deformable circumferential members  814 . In some embodiments, the one or more deformable circumferential members  814  are chamfered along at least a portion of the distal end of the one or more deformable circumferential members  814  to facilitate insertion of the proximal end of the lead or the lead extension into the elongated opening. Likewise, in some embodiments the proximal end of the proximal flange  826  is chamfered along at least a portion of a circumference of the proximal end of the proximal flange  826  to facilitate insertion of the proximal end of the lead or the lead extension into the elongated opening. 
         [0052]    In at least some embodiments, the proximal end of the lead or the lead extension  804  may be inserted into the clip  802  by squeezing the one or more deformable circumferential members  814  in proximity to one or more ends of the major axis  818  to deform the one or more deformable circumferential members  814  into an approximately round shape. When the one or more deformable circumferential members  814  are deformed into an approximately round shape, the proximal end of the lead or the lead extension  804  may be disposed into the clip  802 . Once the proximal end of the lead or the lead extension  804  is at least partially inserted into the clip  802  and the squeezing is ceased, the one or more deformable circumferential members  814  reform to an elongated shape and the minor axis  820  of the one or more deformable circumferential members  814  press against the proximal end of the lead or the lead extension  804 . 
         [0053]    In at least some embodiments, the proximal end of the lead or the lead extension  804  may be disposed in the clip  802  by application of a compressive force between the proximal end of the lead or the lead extension  804  and the clip  802 . For example, in some embodiments, a force may be applied to the proximal end of the lead or the lead extension  804  while pressed against the elongated opening of the clip  802  to deform the elongated opening of the clip  802  and allow passage of the proximal end of the lead or the lead extension  804  into the clip  802 . In other embodiments, a force may be applied to the clip  802  while the elongated opening of the clip  802  is pressed against the proximal end of the lead or the lead extension  804  to deform the elongated opening of the clip  802  and allow passage of the proximal end of the lead or the lead extension  804  into the clip  802 . In at least some embodiments, insertion of the proximal end of the lead or the lead extension  804  into the elongated opening may be facilitated by the chamfered proximal flange  826 . In at least some embodiments, the proximal end of the lead or the lead extension  804  may be inserted into the clip  802  by both squeezing the one or more deformable circumferential members  814  and applying a compressive force between the clip  802  and the proximal end of the lead or the lead extension  804  when the proximal end of the lead or the lead extension  804  is pressed against the elongated opening. 
         [0054]    In at least some embodiments, the clip  802  is configured and arranged so that when the proximal end of the lead or the lead extension  804  is fully inserted into the clip  802 , the proximal flange  826  rests against the base  812  and the portions of the one or more deformable circumferential members  814 , on or in proximity to, the minor axis  820  of the elongated opening engage the annular groove  824  and secure the proximal end of the lead or the lead extension to the clip  802 . 
         [0055]    In at least some embodiments, a signal, such as an audible sound or a tactile signal, is emitted when the one or more deformable circumferential members  814  engage the annular groove  824  of the proximal end of the lead or the lead extension  804 . For example, in one embodiment the one or more deformable circumferential members  814  “snap” when the one or more deformable circumferential members  814  engage the annular groove  824 .  FIG. 8B  is a schematic perspective view of one embodiment of the proximal end of the lead or the lead extension  804  secured in the clip  802 . 
         [0056]    The clip  802  can be formed using any high-strength, biocompatible material suitable for mounting to a connector of an electrical stimulation system. Examples of suitable materials include plastic resins such as PEEK, hard polyurethane, polycarbonate, or other high-strength plastic resins, as well as other high-strength materials, such as stainless steel, titanium, ceramics, and the like, as well as combinations thereof. The clip  802  may be formed in the desired shape by any process including, for example, stamping, molding (including injection molding), casting, and the like. In at preferred embodiments, the clip  802  is formed by stamping stainless steel or titanium from a progressive die. 
         [0057]    In at least some embodiments, a lead or a lead extension may be secured to a connector by a retention assembly incorporating a “slider” type of connection.  FIG. 9A  is a schematic perspective view of another embodiment of a retention assembly  900 . The retention assembly  900  includes a sliding lock  902  configured and arranged to be mounted to a proximal end of a connector (see e.g.,  144  of  FIGS. 2 and 3A , and  322  and  350  of  FIG. 3B ) and a proximal end of a lead or a lead extension  904  configured and arranged for insertion into the sliding lock  902 . In  FIGS. 9A-9D , the connector has been omitted for clarity of illustration. The sliding lock  902  includes a housing  906  and an attached slider  908 . In at least some embodiments, the housing  906  defines an insertion port  910  configured and arranged for receiving the proximal end of the lead or the lead extension  904 . The housing  906  also includes one or more ramps  912  and  914  disposed on one side of the insertion port  910 . 
         [0058]    In at least some embodiments, the slider  908  has a horse-shoe shape and includes two ends  916  and  918  that slide against the housing  906  in a direction indicated by directional arrow  920 . The slider  908  also includes a cross-bar  922  coupled to each of the two ends  916  and  918  of the slider  908 . In at least some embodiments, the slider  908  is configured and arranged to control passage of the proximal end of the lead or the lead extension in and out of the insertion port  910  by sliding between an open position and a retaining position. In  FIG. 9A , the multi-piece element  902  is shown in a retaining position. In a retaining position, the cross-bar  922  extends partially into the insertion port  910 . In at least some embodiments, when the slider  908  is slid in the direction indicated by directional arrow  920 , the amount of the cross-bar  922  extending into the insertion port  910  decreases, until eventually the cross-bar  922  does not extend into the insertion port  910 , at which point the sliding lock  902  is in an open position and may receive the proximal end of the lead or the lead extension  904 . 
         [0059]    In at least some embodiments, the sliding lock  902  is maintained in the retaining position by a cantilever spring embodied by the slider  908 . When the sliding lock  902  is in the retaining position, as shown in  FIG. 9A , the ends  916  and  918  of the slider  908  rest against an outer surface of the housing  906  superior to the one or more ramps  912  and  914  disposed on the housing  906 . When the slider  908  is slid in the direction indicated by the directional arrow  920  into an open position, one or more of the ends  916  and  918  slide along the one or more ramps  912  and  914 , causing one or more of the ends  916  and  918  to deform and separate from one another. In at least some embodiments, additional amounts of force are needed to slide the slider  908  in the direction indicated by the directional arrow  920  as the distance between the ends  916  and  918  of the slider  908  increases. Thus, in at least some embodiments, when the force applied to the slider  908  is ceased, the slider  908  slides in a direction opposite to the direction indicated by the directional arrow  920  and the sliding lock  902  returns to a retained position. 
         [0060]    In at least some embodiments, one or more of the ends  916  and  918  of the slider  908  include a vertical slit, such as vertical slit  924 , dividing the end  918  into a proximal portion and a distal portion, such as proximal portion  926  and distal portion  928 . In at least some embodiments, the cross-bar  922  is attached to the proximal portions of each end  916  and  918  the distal portions of the ends  916  and  918  are configured and arranged to slide along the one or more ramps  912  and  914 . Thus, in at least some embodiments, the distal portions of the ends  916  and  918  of the slider  908  can deform against the ramps  912  and  914  without stretching the cross-bar  922 . The proximal end of the lead of the lead extension  904  includes a plurality of terminals, such as terminal  936 , disposed at the proximal end of the lead or the lead extension  904 . The proximal end of the lead or the lead extension  904  also includes an annular groove  938  proximal to the plurality of terminals. 
         [0061]      FIG. 9B  is a schematic perspective view of one embodiment of the sliding lock  902  in an open position. In at least some embodiments, as shown in  FIG. 9B , the distal portions of the ends  916  and  918  are deformed outward in directions indicated by directional arrows  930  and  932 , respectively, as the distal portions of the ends  916  and  918  slide along the ramps  912  and  914 , respectively. The insertion port  910  is unobstructed and the proximal end of the lead or the lead extension  904  can be inserted into the insertion port  910  of the sliding lock  902 , as shown by directional arrow  934 . The proximal end of the lead of the lead extension  904  includes a plurality of terminals, such as the terminal  936 , disposed at the proximal end of the lead or the lead extension  904 . The proximal end of the lead or the lead extension  904  also includes the annular groove  938  proximal to the plurality of terminals 
         [0062]    In at least some embodiments, once the proximal end of the lead or the lead extension is inserted into the sliding lock  902 , the force applied to the slider  908  can be ceased, causing the slider  908  to return to the retaining position, thereby securing the proximal end of the lead or the lead extension  904  in the sliding lock  902 . In at least some embodiments, application of force may not be needed to maintain the slider  908  in an open position. In at least some embodiments, a friction force may be employed to maintain the slider  908  in an open position.  FIG. 9C  is a schematic perspective view of one embodiment of the proximal end of the lead or the lead extension  904  secured in the sliding lock  902 . 
         [0063]    In at least some embodiments, the cross-bar  922  is configured and arranged to engage the annular groove  938  disposed on the proximal end of the lead or the lead extension  904 .  FIG. 9D  is a schematic perspective, longitudinal cross-sectional view of one embodiment of the proximal end of the lead or the lead extension  904  secured in the sliding lock  902  while the sliding lock  902  is in a retaining position. The proximal end of the lead of the lead extension  904  includes a plurality of terminals, such as the terminal  936 , the annular groove  938 , and the proximal flange  940 . In at least some embodiments, when the proximal end of the lead or the lead extension is fully inserted into the insertion port  910  and the slider  908  is released to secure the proximal end of the lead or the lead extension  904 , the cross-bar  922  is configured and arranged to engage the annular groove  932  of the proximal end of the lead or the lead extension  904 . In at least some embodiments, a signal, such as an audio signal or a tactile signal, is emitted when the cross-bar  922  engages the annular groove  938  of the proximal end of the lead or the lead extension  904 . For example, in one embodiment the cross-bar  922  “snaps” when the cross-bar  922  engages the annular groove  938 . 
         [0064]    The sliding lock  902  can be formed using any high-strength, biocompatible material suitable for mounting to a connector of an electrical stimulation system. Examples of suitable materials include plastic resins such as PEEK, hard polyurethane, polycarbonate, or other high-strength plastic resins, as well as other high-strength materials, such as stainless steel, ceramics, and the like, as well as combinations thereof. The sliding lock  902  may be formed in the desired shape by any process including, for example, molding (including injection molding), casting, and the like. In a preferred embodiments, the sliding lock  902  is formed from plastic. 
         [0065]      FIG. 10  is a schematic overview of one embodiment of components of an electrical stimulation system  1000  including an electronic subassembly  1010  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. 
         [0066]    Some of the components (for example, power source  1012 , antenna  1018 , receiver  1002 , and processor  1004 ) 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  1012  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. 
         [0067]    As another alternative, power can be supplied by an external power source through inductive coupling via the optional antenna  1018  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. 
         [0068]    If the power source  1012  is a rechargeable battery, the battery may be recharged using the optional antenna  1018 , 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. 
         [0069]    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  1004  is generally included to control the timing and electrical characteristics of the electrical stimulation system. For example, the processor  1004  can, if desired, control one or more of the timing, frequency, strength, duration, and waveform of the pulses. In addition, the processor  1004  can select which electrodes can be used to provide stimulation, if desired. In some embodiments, the processor  1004  may select which electrode(s) are cathodes and which electrode(s) are anodes. In some embodiments, the processor  1004  may be used to identify which electrodes provide the most useful stimulation of the desired tissue. 
         [0070]    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  1008  that, for example, allows modification of pulse characteristics. In the illustrated embodiment, the processor  1004  is coupled to a receiver  1002  which, in turn, is coupled to the optional antenna  1018 . This allows the processor  1004  to receive instructions from an external source to, for example, direct the pulse characteristics and the selection of electrodes, if desired. 
         [0071]    In one embodiment, the antenna  1018  is capable of receiving signals (e.g., RF signals) from an external telemetry unit  1006  which is programmed by a programming unit  1008 . The programming unit  1008  can be external to, or part of, the telemetry unit  1006 . The telemetry unit  1006  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  1006  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  1008  can be any unit that can provide information to the telemetry unit  1006  for transmission to the electrical stimulation system  1000 . The programming unit  1008  can be part of the telemetry unit  1006  or can provide signals or information to the telemetry unit  1006  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  1006 . 
         [0072]    The signals sent to the processor  1004  via the antenna  1018  and receiver  1002  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  1000  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  1018  or receiver  1002  and the processor  1004  operates as programmed. 
         [0073]    Optionally, the electrical stimulation system  1000  may include a transmitter (not shown) coupled to the processor  1004  and the antenna  1018  for transmitting signals back to the telemetry unit  1006  or another unit capable of receiving the signals. For example, the electrical stimulation system  1000  may transmit signals indicating whether the electrical stimulation system  1000  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  1004  may also be capable of transmitting information about the pulse characteristics so that a user or clinician can determine or verify the characteristics. 
         [0074]    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.