Flexible Neural Localization Devices and Methods

Abstract

Described herein are devices, systems and methods for determining if a nerve is nearby a device or portion of a device. The neural stimulation tools described herein are configured to be flexible and low-profile, so that they can be used within body regions that may be tortuous or difficult to reach, such as within a compressed or partially occluded neural foramen. In most cases, these tools described herein are ribbon-shaped and adapted to be manipulated bimanually, for example, by applying force to the ends of the devices from separate locations outside of the patient's body. Thus, in some of the exemplary neural localization devices described herein, the distal end region of the device are configured to couple to the proximal end of a guidewire. One or more surfaces of the devices may include an electrode or multi-polar network of electrodes configured to stimulate only nerves within a predetermined distance of a particular face of the device.

1 . A bimanually controlled neural localization device capable of determining if a nerve is nearby a region of the device, the device comprising:
 a flexible elongate body;   a stimulation region on the elongate body; and   a guidewire coupler at the distal end region of the elongate body,   wherein the guidewire coupler is configured such that the elongate body is removably attachable to a proximal end region of a guidewire such that the stimulation region can be pulled into position by pulling on the guidewire while the proximal end region of the guidewire is held stationary by the guidewire coupler with respect to the distal end region of the elongate body.   
     
     
         2 . The device of  claim 1 , wherein the flexible elongate body has an axial length, a width and a thickness, wherein the axial length is greater than the width, and the width is greater than the thickness. 
     
     
         3 . The device of  claim 1 , wherein the flexible elongate body is ribbon shaped having a first side and a second side, wherein the first and second sides are substantially parallel. 
     
     
         4 . The device of  claim 3 , wherein the stimulation region is on the first side of the elongate body and is configured to emit a stimulation field along at least a portion of the length of the first side of the elongate body. 
     
     
         5 . The device of  claim 4 , further comprising a stimulation region on the second side of the elongate body and is configured to emit a stimulation field along at least a portion of the length of the second side of the elongate body. 
     
     
         6 . The device of  claim 1 , wherein the stimulation region includes a stimulation electrode that is configured to emit a stimulation field. 
     
     
         7 . The device of  claim 6 , wherein the electrode is a proud electrode. 
     
     
         8 . The device of  claim 6 , wherein the stimulation region includes a pair of bipolar electrodes. 
     
     
         9 . The device of  claim 1 , wherein the stimulation region includes a bipolar network, wherein the bipolar network comprises an anode and a cathode configured to form a bipolar stimulation field. 
     
     
         10 . The device of  claim 9 , wherein the bipolar network includes a plurality of anodes and a plurality of cathodes, wherein the plurality of anodes and the plurality of cathodes are configured to form an effectively continuous bipole field along a portion of the flexible elongate body. 
     
     
         11 . The device of  claim 10 , wherein the plurality of anodes are in electrical communication with a first anodal conductor. 
     
     
         12 . The device of  claim 11 , wherein the plurality of cathodes are in electrical communication with a first cathodal conductor. 
     
     
         13 . The device of  claim 1 , the elongate body further comprising an insulation element disposed along the length of the stimulation region configured to insulate a first portion of the stimulation region from a second portion of the stimulation region. 
     
     
         14 . The device of  claim 1 , wherein the stimulation region is configured to emit a stimulation field in a first direction from the elongate body and to emit a stimulation field in a second direction from the elongate body, wherein the second direction is different than the first direction. 
     
     
         15 . The device of  claim 1 , further comprising a proximal handle coupled to the elongate body, the handle having a control for selecting activation of either a stimulation field in a first direction from the elongate body or a stimulation field in a second direction from the elongate body. 
     
     
         16 . The device of  claim 1 , further comprising radio-opaque markers distributed along the length of the elongate body. 
     
     
         17 . The device of  claim 1 , further comprising a radio-opaque marker on the elongate body distal to the stimulation region and a radio-opaque marker proximal to the stimulation region, such that the proximal and distal radio-opaque markers delineate the stimulation region. 
     
     
         18 . The device of  claim 17 , wherein the radio-opaque marker comprises a ring coil. 
     
     
         19 . The device of  claim 17 , wherein the radio-opaque marker comprises a hole defined by the elongate body. 
     
     
         20 . A bimanually controlled neural localization device capable of determining if a nerve is nearby a region of the device, the device comprising:
 a flexible elongate body;   a first stimulation region on the elongate body that is configured to emit a stimulation field in a first direction from the elongate body;   a second stimulation region on the elongate body that is configured to emit a stimulation field in a second direction from the elongate body, wherein the second direction is different than the first direction; and   a flexible guide at the distal end of the elongate body,   wherein the guide has a sharp distal end for penetrating tissue and is configured such that the stimulation region can be pulled into position by pulling on the guide.   
     
     
         21 . The device of  claim 20 , wherein the elongate body further comprises a guidewire coupler at the distal end region of the elongate body and wherein the flexible guide is a guidewire configured to removably couple to the guidewire coupler such that the stimulation region can be pulled into position by pulling on the guidewire while the proximal end region of the guidewire is held stationary by the guidewire coupler with respect to the distal end region of the elongate body. 
     
     
         22 . The device of  claim 20 , wherein the flexible elongate body has an axial length, a width and a thickness, wherein the axial length is greater than the width, and the width is greater than the thickness. 
     
     
         23 . The device of  claim 20 , wherein the flexible elongate body is ribbon shaped having a first side and a second side, wherein the first and second sides are substantially parallel. 
     
     
         24 . The device of  claim 23 , wherein the first stimulation region is on the first side of the elongate body and is configured to emit a stimulation field along at least a portion of the length of the first side of the elongate body. 
     
     
         25 . The device of  claim 24 , wherein the second stimulation region is on the second side of the elongate body and is configured to emit a stimulation field along at least a portion of the length of the second side of the elongate body. 
     
     
         26 . The device of  claim 20 , wherein the stimulation regions each include a stimulation electrode that is configured to emit a stimulation field. 
     
     
         27 . The device of  claim 26 , wherein the electrode is a proud electrode. 
     
     
         28 . The device of  claim 26 , wherein the stimulation regions each include a pair of bipolar electrodes. 
     
     
         29 . The device of  claim 20 , wherein the stimulation regions each include a bipolar network, wherein the bipolar network comprises an anode and a cathode configured to form a bipolar stimulation field. 
     
     
         30 . The device of  claim 29 , wherein the bipolar network includes a plurality of anodes and a plurality of cathodes, wherein the plurality of anodes and the plurality of cathodes are configured to form an effectively continuous bipole field along a portion of the flexible elongate body. 
     
     
         31 . The device of  claim 30 , wherein the plurality of anodes are in electrical communication with a first anodal conductor. 
     
     
         32 . The device of  claim 30 , wherein the plurality of cathodes are in electrical communication with a first cathodal conductor. 
     
     
         33 . The device of  claim 20 , the elongate body further comprising an insulation element disposed along the length of at least one of the first stimulation region and the second stimulation region, wherein the insulation element is configured to insulate a first portion of a stimulation region from a second portion of a stimulation region and to insulate the first stimulation region from the second stimulation region. 
     
     
         34 . The device of  claim 20 , further comprising a proximal handle coupled to the elongate body, the handle having a control for selecting activation of either the first or second stimulation regions. 
     
     
         35 . The device of  claim 20 , further comprising radio-opaque markers distributed along the length of the elongate body. 
     
     
         36 . The device of  claim 20 , further comprising a radio-opaque marker on the elongate body distal to both the first and the second stimulation regions and a radio-opaque marker proximal to both the first and the second stimulation regions, such that the proximal and distal radio-opaque markers delineate the first and second stimulation regions. 
     
     
         37 . The device of  claim 36 , wherein the radio-opaque marker comprises a ring coil. 
     
     
         38 . The device of  claim 36 , wherein the radio-opaque marker comprises a hole defined by the elongate body. 
     
     
         39 . A bimanually controlled neural localization device capable of determining if a nerve is nearby a region of the device, the device comprising:
 a flexible elongate body, the elongate body comprising:
 a proximal end configured to extend out of a first portion of a patient's body for manipulation of the proximal end; 
 a distal flexible guide region configured to extend from a second portion of the patient's body for manipulation of the distal end, and 
 a stimulation region between the proximal end and distal flexible guide region, 
 wherein the distal flexible guide region has a sharp distal end for penetrating tissue and is configured such that the stimulation region can be pulled into position by pulling on the distal flexible guide region. 
   
     
     
         40 . The device of  claim 39 , wherein the distal flexible guide region has a free length of at least 3 inches. 
     
     
         41 . The device of  claim 39 , wherein the distal flexible guide region has a free length of at least 10 inches. 
     
     
         42 . The device of  claim 39 , wherein the stimulation region has an axial length, a width and a thickness, wherein the axial length is greater than the width, and the width is greater than the thickness. 
     
     
         43 . The device of  claim 39 , wherein the elongate body is ribbon shaped having a first side and a second side, wherein the first and second sides are substantially parallel. 
     
     
         44 . The device of  claim 43 , wherein the stimulation region is on the first side of the elongate body and is configured to emit a stimulation field along at least a portion of the length of the first side of the elongate body. 
     
     
         45 . The device of  claim 44 , further comprising a second stimulation region on the second side of the elongate body that is configured to emit a stimulation field along at least a portion of the length of the second side of the elongate body. 
     
     
         46 . The device of  claim 39 , wherein the stimulation region includes a stimulation electrode that is configured to emit a stimulation field. 
     
     
         47 . The device of  claim 46 , wherein the electrode is a proud electrode. 
     
     
         48 . The device of  claim 46 , wherein the stimulation region includes a pair of bipolar electrodes. 
     
     
         49 . The device of  claim 39 , wherein the stimulation region includes a bipolar network, wherein the bipolar network comprises an anode and a cathode configured to form a bipolar stimulation field. 
     
     
         50 . The device of  claim 49 , wherein the bipolar network includes a plurality of anodes and a plurality of cathodes, wherein the plurality of anodes and the plurality of cathodes are configured to form an effectively continuous bipole field along a portion of the flexible elongate body. 
     
     
         51 . The device of  claim 50 , wherein the plurality of anodes are in electrical communication with a first anodal conductor. 
     
     
         52 . The device of  claim 50 , wherein the plurality of cathodes are in electrical communication with a first cathodal conductor. 
     
     
         53 . The device of  claim 39 , the elongate body further comprising an insulation element disposed along the length of the stimulation region configured to insulate a first portion of the stimulation region from a second portion of the stimulation region. 
     
     
         54 . The device of  claim 39 , further comprising a proximal handle coupled to the elongate body, the handle having a control for selecting activation of either a stimulation field in a first direction from the elongate body or a stimulation field in a second direction from the elongate body. 
     
     
         55 . The device of  claim 39 , further comprising radio-opaque markers distributed along the length of the elongate body. 
     
     
         56 . The device of  claim 39 , further comprising a radio-opaque marker on the elongate body distal to the stimulation region and a radio-opaque marker proximal to the stimulation region, such that the proximal and distal radio-opaque markers delineate the stimulation region. 
     
     
         57 . The device of  claim 56 , wherein the radio-opaque marker comprises a ring coil. 
     
     
         58 . The device of  claim 56 , wherein the radio-opaque marker comprises a hole defined by the elongate body. 
     
     
         59 . The device of  claim 39 , wherein the stimulation region is configured to emit a stimulation field in a first direction from the elongate body and to emit a stimulation field in a second direction from the elongate body, wherein the second direction is different than the first direction. 
     
     
         60 . A system capable of determining if a nerve is nearby a region of a device, the system comprising:
 a bimanually controlled neural localization device, the device comprising:
 a flexible elongate body, 
 a stimulation region on the elongate body, and 
 a guidewire coupler at the distal end region of the elongate body; and 
   a guidewire configured to removably couple to the guidewire coupler of the neural localization device such that the stimulation region can be pulled into position by pulling on the guidewire while the proximal end region of the guidewire is held stationary by the guidewire coupler with respect to the distal end region of the elongate body.   
     
     
         61 . The system of  claim 60 , the neural localization device further comprising a proximal handle coupled to the elongate body, the handle having a control for selecting activation of either a stimulation field in a first direction from the elongate body or a stimulation field in a second direction from the elongate body. 
     
     
         62 . The system of  claim 60 , further comprising a distal handle configured to couple to the distal end of the guidewire such that the stimulation region can be pulled into position by pulling on distal handle thereby pulling on the guidewire. 
     
     
         63 . The system of  claim 62 , further comprising a proximal handle configured to couple to the proximal end of the elongate body such that the stimulation region can be pulled into position by using at least one of the distal handle and the proximal handle. 
     
     
         64 . The system of  claim 60 , wherein the guidewire coupler is further configured to couple to a guidewire such that the stimulation region may be positioned using the guidewire without the guidewire disengaging from the guidewire coupler. 
     
     
         65 . A method of determining if a nerve is nearby a region of a bimanually controlled device, the method comprising:
 passing a distal end of a neural localization device in a first direction toward a target tissue, at least partially around a target tissue, and away from the target tissue, such that a stimulation region on the neural localization device is positioned adjacent to the target tissue;   energizing the stimulation region to emit a stimulation field from the elongate body; and   determining if a nerve has been stimulated by the emitted field.   
     
     
         66 . The method of  claim 65 , wherein the step of passing distal end of a neural localization device comprises passing a guidewire in a first direction toward a target tissue, at least partially around a target tissue, and away from the target tissue and pulling the stimulation region on the neural localization device adjacent to the target tissue using the guidewire. 
     
     
         67 . The method of  claim 66 , further comprising the step of coupling a flexible tissue-modification device to the guidewire. 
     
     
         68 . The method of  claim 65 , wherein the step of passing the distal end of a neural localization device comprises applying tension to both the proximal end and the distal end of the a neural localization device. 
     
     
         69 . The method of  claim 65 , wherein the target tissue comprises tissue within a spinal foramen. 
     
     
         70 . The method of  claim 65 , further comprising the steps of
 passing a flexible tissue-modification device in a first direction toward a target tissue and at least partially around a target tissue, such that a tissue modification region of the device is positioned adjacent to the target tissue, wherein the flexible tissue-modification device comprises a flexible elongate body having the tissue modification region including at least one tissue modifying element oriented in the same direction as stimulation region of the ribbon neural localization device; and   urging the tissue modification region against the target tissue by pulling the tissue-modification device from at least one end of the device.   
     
     
         71 . The method of  claim 65 , wherein the flexible elongate body is ribbon shaped having a first side and a second side, wherein the first and second sides are substantially parallel, and wherein the first side is positioned to face the target tissue. 
     
     
         72 . The method of  claim 71 , wherein the neural localization device further comprises a second stimulation region on the second side of the elongate body, and wherein the passing step further comprises positioning the second stimulation region on the neural localization device adjacent to non-target tissue. 
     
     
         73 . The method of  claim 72 , the energizing step further comprising energizing a second stimulation region to emit a second stimulation field from the elongate body. 
     
     
         74 . The method of  claim 73 , the determining step further comprising determining a first threshold stimulation amount from the first stimulation region to elicit an EMG response and a second threshold stimulation amount from the second stimulation region to elicit an EMG response. 
     
     
         75 . The method of  claim 74 , further comprising the step of comparing the first threshold stimulation amount to the second threshold stimulation amount. 
     
     
         76 . The method of  claim 65 , wherein the energizing step further comprises energizing a stimulation electrode of the stimulation region to emit a stimulation field from the elongate body. 
     
     
         77 . The method of  claim 65 , wherein the energizing step further comprises energizing an anode and a cathode of the stimulation region, configured to form a bipolar network, to emit a bipolar stimulation field from the elongate body. 
     
     
         78 . The method of  claim 65 , further comprising the step of selecting activation of a stimulation field in a first direction from the elongate body or activation of a stimulation field in a second direction from the elongate body, wherein the second direction is different than the first direction. 
     
     
         79 . The method of  claim 65 , the passing step further comprising using radio-opaque markers distributed along the length of the elongate body to determine the position of the stimulation region on the neural localization device adjacent to the target tissue. 
     
     
         80 . The method of  claim 65 , the determining step further comprising determining a threshold stimulation amount from the stimulation region to elicit an EMG response. 
     
     
         81 . The method of  claim 65 , the determining step further comprising determining if a nerve is present between the flexible neural localization device and the target tissue. 
     
     
         82 . A method of determining if a nerve is nearby a region of a bimanually controlled device, the method comprising:
 passing a distal tip of a guidewire into a patient, around a target tissue, and out of the patient so that proximal and distal ends of the guidewire extend from the patient;   coupling the distal end of a neural localization device to the proximal end region of the guidewire such that the proximal end region of the guidewire is held stationary with respect to the distal end of a neural localization device;   pulling the neural localization device into position within the patient using the guidewire;   energizing a stimulation region of the device to emit a stimulation field; and   determining if a nerve has been stimulated by the emitted field.   
     
     
         83 . The method of  claim 82 , wherein the target tissue comprises tissue within a spinal foramen. 
     
     
         84 . The method of  claim 82 , further comprising the step of coupling a flexible tissue-modification device to the proximal end region of the guidewire such that the proximal end region of the guidewire is held stationary with respect to the distal end of the flexible tissue-modification device. 
     
     
         85 . The method of  claim 84 , further comprising the steps of:
 pulling the flexible tissue-modification device into position within the patient using the guidewire, wherein the flexible tissue-modification device comprises a flexible elongate body having the tissue modification region including at least one tissue modifying element oriented in the same direction as the stimulation region of the ribbon neural localization device; and   urging the tissue modification region against the target tissue by pulling the tissue-modification device from at least one end of the device.   
     
     
         86 . The method of  claim 82 , wherein at least a portion of the neural localization device is ribbon shaped having a first side and a second side, wherein the first and second sides are substantially parallel, and wherein the first side is positioned to face the target tissue. 
     
     
         87 . The method of  claim 86 , wherein the neural localization device further comprises a second stimulation region on the second side of the neural localization device, and wherein the pulling step further comprises pulling the neural localization device into position such that the second stimulation region on the neural localization device is adjacent to non-target tissue. 
     
     
         88 . The method of  claim 87 , the energizing step further comprising energizing a second stimulation region to emit a second stimulation field. 
     
     
         89 . The method of  claim 88 , the determining step further comprising determining a first threshold stimulation amount from the first stimulation region to elicit an EMG response and a second threshold stimulation amount from the second stimulation region to elicit an EMG response. 
     
     
         90 . The method of  claim 89 , further comprising the step of comparing the first threshold stimulation amount to the second threshold stimulation amount. 
     
     
         91 . The method of  claim 82 , wherein the energizing step further comprises energizing a stimulation electrode of the stimulation region to emit a stimulation field. 
     
     
         92 . The method of  claim 82 , wherein the energizing step further comprises energizing an anode and a cathode of the stimulation region, configured to form a bipolar network, to emit a bipolar stimulation field. 
     
     
         93 . The method of  claim 82 , further comprising the step of selecting activation of a stimulation field in a first direction from the elongate body or activation of a stimulation field in a second direction from the elongate body, wherein the second direction is different than the first direction. 
     
     
         94 . The method of  claim 82 , the pulling step further comprising using radio-opaque markers distributed along the length of the neural localization device to position the stimulation region adjacent to the target tissue. 
     
     
         95 . The method of  claim 82 , the determining step further comprising determining a threshold stimulation amount from the stimulation region to elicit an EMG response. 
     
     
         96 . The method of  claim 82 , the pulling step further comprising pulling the neural localization device into position within the patient using a distal handle coupled to the guidewire. 
     
     
         97 . The method of  claim 96 , the pulling step further comprising pulling the neural localization device into position within the patient using at least one of the distal handle and a proximal handle coupled to the neural localization device. 
     
     
         98 . The method of  claim 82 , the pulling step further comprising pulling the neural localization device into position within the patient using the guidewire without disengaging the guidewire from the neural localization device. 
     
     
         99 . The method of  claim 82 , the determining step further comprising determining if a nerve is present between the flexible neural localization device and the target tissue. 
     
     
         100 . The method of  claim 82 , the pulling step further comprising using radio-opaque markers distributed along the length of the neural localization device to determine the position of the stimulation region on the neural localization device adjacent to the target tissue. 
     
     
         101 . The method of  claim 82 , the pulling step further comprising positioning a radio-opaque marker such that it is aligned with a medial aspect of a pedicle of a patient's spine. 
     
     
         102 . A method of determining if a nerve is nearby a region of a device, the method comprising:
 passing a flexible distal end of a neural localization device having a stimulation region into a patient, around a target tissue, and out of the patient so that proximal and distal ends of the neural localization device extend from the patient and the stimulation region is adjacent to the target tissue;   pulling on one or both of the proximal and distal ends of the neural localization device to move the stimulation region closer to the target tissue;   energizing the stimulation region to emit a stimulation field in a first direction from the elongate body, wherein the first direction is toward the target tissue;   pushing on one or both of the proximal and distal ends of the neural localization device to move the stimulation region away from the target tissue;   energizing the stimulation region to emit a stimulation field in a second direction from the elongate body, wherein the second direction is away the target tissue; and   determining the position of the nerve with respect to the elongate body.   
     
     
         103 . The method of  claim 102 , wherein the step of passing distal end of a neural localization device comprises:
 passing a guidewire in a first direction toward a target tissue, at least partially around a target tissue, and away from the target tissue so that proximal and distal ends of the guidewire extend from the patient; and   pulling the stimulation region on the neural localization device adjacent to the target tissue using the guidewire.   
     
     
         104 . The method of  claim 103 , the step of pulling on one or both of the proximal and distal ends of the neural localization device comprises pulling the further comprising pulling on one or both of the proximal and distal ends of the neural localization device to move the stimulation region closer to the target tissue without disengaging the guidewire from the neural localization device. 
     
     
         105 . The method of  claim 103 , the step of pushing on one or both of the proximal and distal ends of the neural localization device further comprises pushing on one or both of the proximal and distal ends of the neural localization device to move the stimulation region away from the target tissue without disengaging the guidewire from the neural localization device. 
     
     
         106 . The method of  claim 103 , further comprising the step of coupling the neural localization device to the guidewire. 
     
     
         107 . The method of  claim 102 , wherein the step of passing the distal end of a neural localization device comprises applying tension to both the proximal end and the distal end of the a neural localization device. 
     
     
         108 . The method of  claim 102 , wherein the target tissue comprises tissue within a spinal foramen. 
     
     
         109 . The method of  claim 102 , wherein the flexible elongate body is ribbon shaped having a first side and a second side, wherein the first and second sides are substantially parallel, and wherein the first side is positioned to face the target tissue. 
     
     
         110 . The method of  claim 102 , wherein the determining step further comprises determining a first threshold stimulation amount from the stimulation region in the first direction to elicit an EMG response and a second threshold stimulation amount from second stimulation region in the second direction to elicit an EMG response. 
     
     
         111 . The method of  claim 110 , further comprising comparing the first threshold stimulation amount to the second threshold stimulation amount. 
     
     
         112 . The method of  claim 102 , wherein the energizing steps further comprise energizing a stimulation electrode of the stimulation region to emit a stimulation field from the elongate body. 
     
     
         113 . The method of  claim 102 , wherein the energizing steps further comprise energizing an anode and a cathode of the stimulation region, configured to form a bipolar network, to emit a bipolar stimulation field from the elongate body. 
     
     
         114 . The method of  claim 102 , the determining step further comprising determining if a nerve is present between the flexible neural localization device and the target tissue. 
     
     
         115 . A method of determining if a nerve is nearby a region of a device, the method comprising:
 positioning a stimulation region of a neural localization device along a curved path such that the stimulation region is adjacent to a nerve;   moving the stimulation region off of the curved path and toward the nerve;   energizing the stimulation region to emit a stimulation field in a first direction from the neural localization device, wherein the first direction is toward the nerve;   moving the stimulation region off of the curved path and away from the nerve;   energizing the stimulation region to emit a stimulation field in a second direction from the neural localization device, wherein the second direction is away the nerve; and   determining the position of the nerve with respect to the neural localization device.   
     
     
         116 . The method of  claim 115 , wherein at least one of the moving the stimulation region steps further comprising pushing a distal portion of the neural localization device by pushing a tube device against the distal portion of the neural localization device. 
     
     
         117 . The method of  claim 116 , wherein the step of pushing the distal portion of the neural localization device further comprises advancing the tube device along the distal end of the neural localization device toward a distal end of the stimulation region of the neural localization device. 
     
     
         118 . The method of  claim 115 , wherein at least one of the moving the stimulation region steps further comprising moving the stimulation region of the elongate body using at least one of the proximal and distal ends of the neural localization device. 
     
     
         119 . The method of  claim 115 , wherein the stimulation region of a neural localization device is ribbon shaped having a first side and a second side, wherein the first and second sides are substantially parallel, and wherein the first side is positioned to face a nerve. 
     
     
         120 . The method of  claim 115 , wherein the step of determining further comprises determining a first threshold stimulation amount from the stimulation region in the first direction to elicit an EMG response and a second threshold stimulation amount from second stimulation region in the second direction to elicit an EMG response. 
     
     
         121 . The method of  claim 120 , further comprising comparing the first threshold stimulation amount to the second threshold stimulation amount. 
     
     
         122 . The method of  claim 115 , wherein the energizing steps further comprise energizing a stimulation electrode of the stimulation region to emit a stimulation field from the elongate body. 
     
     
         123 . The method of  claim 115 , wherein the energizing steps further comprise energizing an anode and a cathode of the stimulation region, configured to form a bipolar network, to emit a bipolar stimulation field from the elongate body. 
     
     
         124 . A method of determining if a nerve is nearby a region of a device, the method comprising:
 advancing a flexible elongate body of a neural localization device into a patient and around a target tissue;   energizing a stimulation region of the elongate body to emit a stimulation field in a first direction from the elongate body;   determining a first threshold amount of energy required to stimulate a measurable response from neural tissue with the stimulation field in the first direction;   energizing a stimulation region of the elongate body to emit a stimulation field in a second direction from the elongate body, wherein the second direction is different from the first direction;   determining a second threshold amount of energy required to stimulate a measurable response from neural tissue with the stimulation field in the second direction; and   applying a ratio of the first threshold and the second threshold, and a magnitude of one of the first threshold and the second threshold to determine if the nerve is in the first direction from the elongate body or in the second direction from the elongate body.   
     
     
         125 . The method of  claim 124 , wherein the step of energizing further comprises energizing a stimulation region of the elongate body until an EMG response is elicited. 
     
     
         126 . The method of  claim 124 , further comprising removing tissue from the intervertebral foramen when the first threshold is less than 5 mA and the ratio is greater than or equal to 4. 
     
     
         127 . The method of  claim 124 , further comprising removing tissue from the intervertebral foramen when the first threshold is greater than or equal to 5 mA and the ratio is greater than or equal to 2. 
     
     
         128 . The method of  claim 124 , further comprising removing tissue from the intervertebral foramen when the first threshold is greater than or equal to 10 mA and the ratio is greater than or equal to 1.5. 
     
     
         129 . The method of  claim 125  further comprising the step of removing tissue from the intervertebral foramen when the first threshold is greater than or equal to 25 mA and the ratio is greater than or equal to 1.3.