Abstract:
In one embodiment, a malleable needle is provided at least three independent electrodes to facilitate the implantation of an electrical stimulation lead for peripheral nerve stimulation. The malleable characteristic of the needle enables the needle to be bent or shaped according to the patient anatomy. Once the needle is appropriately shaped by the physician, the physician inserts the needle into a prospective site for stimulation. The provision of the electrodes enables a suitable number of electrode patterns to be tested to determine whether the stimulation site is satisfactory. By utilizing the malleable needle in this manner, a number of stimulation sites can be tested in an efficient manner to identify an optimal location for implantation of the stimulation lead.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/862,899, filed Oct. 25, 2006, the disclosure of which is fully incorporated herein. 
     
    
     BACKGROUND 
       [0002]    This application is generally related to a method of implanting a lead for peripheral nerve stimulation and peripheral nerve field stimulation using a malleable needle having multiple electrodes. 
         [0003]    Peripheral nerves are nerves in the body other than the nerves of the brain or spinal cord. Peripheral nerve injury may result in the development of chronic intractable pain which in some patients may prove unresponsive to conservative pain management techniques. Peripheral Nerve Stimulation (PNS) has developed as a successful therapy for pain management when the pain is known to result from a specific nerve. Sweet and Wespic first used electrical stimulation of peripheral nerves in the 1960s to mask the sensation of pain with a tingling sensation (paresthesia) caused by the electrical stimulation. Subsequent refinements in the technology, surgical technique and patient selection have led to improved long term results. 
         [0004]    Efforts have also been made to treat psychiatric disorders with peripheral/cranial nerve stimulation. For example, partial benefits with vagus nerve stimulation in patients with depression have been described in U.S. Pat. No. 5,299,569. U.S. Pat. No. 5,263,480 describes that stimulation of the vagus nerve may control depression and compulsive eating disorders. U.S. Pat. No. 5,540,734 teaches stimulation of the trigeminal or glossopharyngeal nerves for psychiatric illness, such as depression. 
         [0005]    Another example of peripheral nerve stimulation includes stimulating the C2 dermatome area to treat occipital neuralgia, which may be defined generally as an intractable headache originating in the back of the head in the vicinity of the C2 dermatome area. This method of delivering electrical stimulation energy to the C2 dermatome area to treat occipital neuralgia involves positioning stimulation electrodes of an implantable electrical stimulation lead with at least one electrode in the fascia superior to in a subcutaneous region proximate the C2 dermatome area. 
         [0006]    More recently, it has been reported that electrical stimulation by a lead implanted in the occipital region is useful to treat a number of disorders. U.S. Patent Application Publication No. 2006/0047325 by Thimineur et al. discloses that patients receiving electrical stimulation of the occipital region have exhibited surprisingly significant psychological and cognitive improvements. Also, U.S. Patent Application Publication No. 2006/0047325 has further disclosed that stimulation in this region has been shown to have an impact on Rheumatoid Arthritis, movement disorders, and obesity in patients. 
         [0007]    The implantation of a stimulation lead within a patient typically occurs through a hollow needle. Specifically, the needle with a stylet inserted within the lumen of the needle is inserted within the patient to a location adjacent to the stimulation site. The stylet is removed and the stimulation lead is inserted through the lumen of the needle to the stimulation site. The needle is then slightly retracted to expose the electrodes of the stimulation lead to tissue. Electrical pulses can then be applied to the stimulation site through the stimulation lead to determine if the correct location has been reached. If the location is incorrect, the stimulation lead and needle are removed and the process is repeated. 
         [0008]    It is also known to utilize a needle with an active tip to verify a stimulation location before lead implantation is attempted. For example, U.S. Pat. No. 6,971,393 to Mamo discloses inserting a needle with an active tip into a stimulation site adjacent to a sacral nerve root to test the effect of stimulation on the patient. Assuming that the test is successful, a larger needle is inserted in the patient to access the same location. A stylet is removed from the needle and a stimulation lead is inserted through the needle. Additional stimulation testing with the implanted lead can also occur if deemed appropriate by the physician. 
       BRIEF SUMMARY 
       [0009]    In one embodiment, a malleable needle is provided at least three independent electrodes to facilitate the implantation of an electrical stimulation lead for peripheral nerve stimulation. The malleable characteristic of the needle enables the needle to be bent or shaped according to the patient anatomy. Once the needle is appropriately shaped by the physician, the physician inserts the needle into a prospective site for stimulation. The provision of the electrodes enables a suitable number of electrode patterns to be tested to determine whether the stimulation site is satisfactory. By utilizing the malleable needle in this manner, a number of stimulation sites can be tested in an efficient manner to identify an optimal location for implantation of the stimulation lead. 
         [0010]    The foregoing has outlined rather broadly various features and technical advantages in order that the detailed description that follows may be better understood. Additional features and/or advantages will be described hereinafter which form the subject of the claims. It should be appreciated that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes. It should also be realized that such equivalent constructions do not depart from the appended claims. The novel features, both as to organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  depicts a cross-sectional view of a malleable needle for use in implanting a stimulation lead for peripheral nerve stimulation according to one representative embodiment. 
           [0012]      FIG. 2  depicts a malleable needle having a plurality of electrodes for use in implanting a stimulation lead for peripheral nerve stimulation according to one representative embodiment. 
           [0013]      FIG. 3  depicts a removable handle for the malleable needle shown in  FIG. 2  according to one representative embodiment. 
           [0014]      FIG. 4  depicts a trial stimulator coupled to a malleable needle for identifying a stimulation location for peripheral nerve stimulation according to one representative embodiment. 
           [0015]      FIG. 5  depicts a cannula adapted to the malleable needle shown in  FIG. 2  according to one representative embodiment. 
           [0016]      FIG. 6  depicts a flowchart for implanting a stimulation lead according to one representative embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Some representative embodiments provide a malleable needle having at least three independent electrodes that can be programmed in a tri-state manner to facilitate implantation of a stimulation lead for peripheral nerve stimulation. A physician may insert the needle into a prospective site for application of electrical pulses for the peripheral nerve stimulation or peripheral nerve field stimulation. 
         [0018]    The needle is preferably malleable so that the physician can alter the needle&#39;s longitudinal shape. For example, if the peripheral nerve stimulation involves stimulating the occipital nerve area of a patient, the physician can shape the needle to conform to the general profile of the back of the patient&#39;s skull thereby allowing the needle to be maintained in or near the patient&#39;s fascia in the occipital region. Alternatively, the physician can alter the shape of the malleable needle to maneuver around an obstacle that impairs access to the desired peripheral nerve tissue. 
         [0019]    Upon insertion into the respective site, the physician may couple the needle to a trial stimulator (i.e., a pulse generator). The physician can adjust the settings of the trial stimulator to test various stimulation pulse patterns. In particular, the physician can apply different electrode polarity combinations to the multiple electrodes in addition to varying pulse amplitude, pulse frequency, and pulse width. By applying the test stimulation pulses, the physician can determine whether the correct location has been selected and whether the stimulation will be effective for the patient&#39;s disorder. 
         [0020]    Referring now to the drawings,  FIG. 1  depicts a cross-sectional view of malleable needle  100  for use in implanting a stimulation lead for peripheral nerve stimulation according to one representative embodiment. In one embodiment, needle  100  comprises core  101  of medical grade stainless steel. In another embodiment, core  101  can comprise any medical grade material that can be formed into a suitable needle as described below. The thickness of core  101  is preferably selected to allow needle  100  to be bent or shape as desired by the physician. Needle  100  may also include deformable material  105  (such as silicone or other deformable material) within the lumen of core  101 . The deformable material  105  preferably possesses a sufficiently low durometer that allows core  101  to be readily bent or shaped. Also, the selection of the durometer of deformable material  105  should permit distribution of the applied bending/shaping force to prevent core  101  from being collapsed at a particular point or developing an undesired crimp. In another embodiment, a stylet such as is described in U.S. Published application Ser. No. 10/637,342, which is incorporated by reference herein, may be used with the present invention. 
         [0021]    To provide electrical isolation between the various electrical contacts  201 , core  101  is coated with insulative material  102  such as a dielectric epoxy material. A surfactant can be added to insulative material  102  to facilitate the coating of core  101 . Additionally or alternatively, a vacuum deposit process can be used to apply a crystal or glass dielectric material on core  101 . Once, the insulative layer  102  is applied, independent electrical traces  103  are applied around the circumference of the needle, e.g., by vacuum deposition. In alternative embodiment, a solid layer of conductive material, such as MP35N or other suitable conductor, could be deposited on the outer surface of core  101  and a suitable YAG or other laser could be utilized to etch trenches in the conductive material to define independent traces  103 . The etching of trenches causes each trace  103  to be electrically isolated from the other traces  103 . As shown in  FIG. 1 , traces  103  are disposed as discrete conductive paths that run longitudinally along needle  100 . Also, three traces  103 A- 103 C are applied to support three independent electrodes  201 , although more traces  103  could be provided to support additional electrodes for alternative embodiments. After the traces  103  are provided, another insulative layer  104  is deposited to maintain the electrical isolation of traces  103  from each other. 
         [0022]      FIG. 2  depicts a longitudinal view of malleable needle  100  according to one representative embodiments. As shown in  FIG. 2 , needle  100  comprises three electrical contacts  201 A- 201 C at a distal end of the needle to function as electrodes. Likewise, needle  100  comprises three electrical contacts  201 D- 201 F at a proximal end of needle  100 . Each contact  201  is preferably implemented in a similar manner. Specifically, a portion of insulative layer  104  is removed above a respective trace  103  wherein the contact  201  is to be formed. Then, conductive material is applied or deposited in a ring-like manner around the needle and over the exposed portion of the respective trace  103 . Accordingly, the ring is then electrically coupled to the exposed trace  103  and is also electrically isolated from the other traces  103 . After the contacts  201  are formed, each trace  103  is coupled to two contacts  201 , i.e., one contact  201  at the proximal end and one contact  201  at the distal end. Thus, application of electrical energy at the contact  201  at the proximal end is conducted by the respective trace  103  to the contact  201  at the distal end. 
         [0023]      FIG. 3  depicts removable handle  300  for malleable needle  100  according to one representative embodiment. Handle  300  preferably provides a convenient structure to permit the physician to manipulate needle  100  through the tissue of the patient in an efficient manner. Also, handle  300  preferably provides an integral connector portion (electrical contacts  301 A- 301 F) to provide a temporary electrical connection between electrodes of a trial lead/cable with the electrodes  201 A- 201 C of the needle during stimulation testing. 
         [0024]      FIG. 4  depicts trial stimulator  402  coupled to malleable needle  100  through stimulation lead  401  for identifying a stimulation location for peripheral nerve stimulation according to one representative embodiment. The physician uses stimulator  402  to generate the electrical pulses to stimulate the nerve tissue of the patient. The stimulator  402  allows the physician to control the amplitude, frequency, and pulse width of the stimulation pulses. Also, the stimulator  402  allows the physician to control the electrode polarities (i.e., each electrode of needle  100  can function as an anode or cathode or function in a high-impedance state). If the physician is unable to obtain satisfactory results from the stimulation after trying a number of different stimulation settings and electrode patterns, the needle is most likely not positioned sufficiently close to the respective nerve tissue. The physician can then readily remove the needle  100  from the current location and replace the needle in another location. 
         [0025]    Handle  300  as shown in  FIG. 3  is preferably readily removable from needle  100  to permit a cannula to be inserted over needle  100  and through the tissue of the patient when the correction stimulation location has been identified.  FIG. 5  depicts cannula  500  adapted to malleable needle  100  according to one representative embodiment. Cannula  500  preferably possesses an inner diameter that is slightly greater than the outer diameter of needle  100  and the stimulation lead to be implanted. Cannula  500  can be constructed of any suitable biocompatible material such as stainless steel or various higher durometer polymers. After cannula  500  is inserted over the needle to the stimulation location, needle  100  is removed to allow the stimulation lead to be inserted through cannula  500  to the stimulation site. 
         [0026]    Although some implementation details have been discussed in regard to  FIGS. 1-4 , other implementations of a malleable needle having a plurality of electrodes can be employed according to alternative embodiments. For example, in lieu of providing electrical traces along the exterior of core  101 , some embodiments may provide conductive wires within the core  101 . For example, a stimulation lead of insulative material embedding conductive wires can be provided within the lumen of core  101 . Apertures can be provided through core  101  to access the stimulation lead, e.g., by laser ablation. A respective aperture can also be provided through a portion of the insulative material of the stimulation lead to access a respective conductive wire. Conductive material can be deposited or otherwise built-up to provide a conductive path to the exterior where an electrical contact is to be formed. Alternatively, a linking wire or bridge can be coupled to the exposed conductive wire of the interior stimulation lead. 
         [0027]      FIG. 6  depicts a flowchart for implanting a stimulation lead according to one representative embodiment. 
         [0028]    In step  601 , needle  100  is bent and/or otherwise shaped to conform to the anatomy of a patient near the location where a lead is to be implanted for peripheral nerve stimulation. Alternatively, the needle can be bent and/or otherwise shaped to allow the physician to avoid any obstructions between the insertion point of the needle and the desired stimulation location. 
         [0029]    In step  602 , the needle  100  is inserted into the patient tissue and, in step  603 , the needle is coupled to a trial stimulator through a suitable lead or cable. In step  604 , stimulation pulses are delivered from the trial stimulator through the needle  100  according to a number of different stimulation settings. The electrode polarities can be varied as well as the pulse amplitude, pulse frequency, and pulse width. 
         [0030]    In step  605 , a decision is made whether the desired result of the peripheral nerve stimulation has been observed (e.g., relief from pain, change in a psychological state, change in cognitive functioning, change in one or several physiological functions, etc.). If the desired result has not been achieved (and the physician has not concluded that it cannot be achieved), the needle is withdrawn and the process returns to step  602  in an attempt to identify another more appropriate stimulation location. 
         [0031]    If the desired result of the stimulation has been observed, the connecting electrical lead/cable is removed and also the handle of the needle is removed (step  606 ). In step  607 , a cannula is inserted over the needle to the stimulation site. In step  608 , the needle is removed from the cannula. In step  609 , a stimulation lead is inserted through the cannula to the stimulation site. In step  610 , further stimulation can be optionally provided through the stimulation lead to verify the correct placement of the stimulation lead. 
         [0032]    Although some representative embodiments and advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the appended claims. Moreover, the scope of the appended claims is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.