Abstract:
The present disclosure is directed to methods for relieving pain associated with an intervertebral disc having a disc nucleus pulposus and an outer annulus fibrosus surrounding the nucleus pulposus. The method includes the steps of providing an elongated thermal or electromagnetic probe member having a flexible guidable region adjacent the distal end thereof; introducing the flexible guidable region of the probe into the annulus fibrosus of the intervertebral disc or nucleons pulpous; and supplying thermal or electromagnetic energy, from an energy source, to heat or induce an electromagnetic field adjacent to the annulus fibrosus sufficient to produce a thermal or electromagnetic effect on the intervertebral disc. The flexible guidable region of the probe may be introduced at a location which is in relative close proximity to the region of intervertebral disc to be thermally or electromagnetically treated.

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    The present application is a Continuation-in-Part Application of U.S. patent application Ser. No. 12/252,560, filed on Oct. 16, 2008, which is a Continuation of U.S. patent application Ser. No. 10/945,656, filed on Sep. 21, 2004, now abandoned, the entire contents of each of these applications is hereby incorporated by reference. 
         [0002]    The present application is also a Continuation-in-Part Application of U.S. patent application Ser. No. 11/391,900, filed on Mar. 29, 2006, which claims the benefit of and priority to U.S. Provisional Application Ser. No. 60/666,827, filed on Mar. 31, 2005, the entire contents of each of these applications hereby incorporated herein by reference. 
     
    
     BACKGROUND 
       [0003]    1. Technical Field 
         [0004]    The present disclosure relates to methods for treating intervertebral disc problems using percutaneous techniques without the need for major surgical intervention, and more particularly, to methods for the insertion of a cannula into the intervertebral disc and the insertion of a thermal probe into the disc material to heat the intervertebral disc thereby relieving and treating abnormalities or pain related to the disc. 
         [0005]    2. Background of Related Art 
         [0006]    The use of thermal therapy in and around the spinal column is known. Also, the insertion of cannula into the intervertebral discs is commonly done for injection of contrast mediums to implement X-ray discograms. This technique is used to detect or diagnose abnormalities or damage to the intervertebral disc. The use of heating of an intervertebral disc to relieve pain is described in U.S. Pat. No. 5,433,739, issued Jul. 18, 1995, and in U.S. Pat. No. 5,571,147, issued Nov. 5, 1996, the entire contents of each of which being incorporated herein by reference. In these patents, electrodes are described for either radiofrequency or resistive thermal heating of all or a portion of the intervertebral disc. Straight, curved, and flexible-tipped electrodes are described for this purpose. The thermal treatment of an intervertebral disc for the relief of back pain is also described within the patents cited above. 
         [0007]    The use of a resistively heated probe adapted to be inserted into the intervertebral disc is described in U.S. Pat. No. 6,073,051, issued Jun. 6, 2000, the entire content of which is incorporated herein by reference. As seen in  FIG. 1 , U.S. Pat. No. 6,073,051, an apparatus or probe for treating intervertebral discs, the apparatus including a flexible catheter  14  which is introduced into the nucleus pulposus “N” and manipulated about (i.e., a functional element  16  of catheter  14  is introduced from a lateral side of nucleus pulposus “N”, opposite the area to be treated, and extended around to the opposite lateral side of nucleus pulposus “N”, adjacent to the area to be treated) an inner wall of the annulus fibrosus along annulus fibrosus/nucleus pulposus interface  28 . Accordingly, functional element or intradiscal section  16  of catheter  14  delivers a therapeutic effect to the area of nucleus pulposus “N” to be treated, i.e., fissures “F”. 
         [0008]    It is desirable to treat the posterior or posterior/lateral portion of the intervertebral disc for the indication of mechanical degeneration of the disc and discogenic back pain. Pain can be derived from degeneration or compression of the intervertebral disc in its posterior or posterior/lateral portions. There is some innervation of the intervertebral disc near the surface of the disc and also within its outer portion known as the annulus fibrosus. Fissures or cracks within the disc caused by age, mechanical trauma, or disc degeneration are believed to be associated with painful symptoms. 
         [0009]    Thus, a configuration of insertion cannula, to approach and enter the intervertebral disc, and a thermal probe to be built into or associated with said cannula, to adequately reach the posterior/lateral and posterior portions of the intervertebral disc, is desirable. Additionally, a novel method of introducing and advancing a thermal probe, toward the tissue to be treated, is also desirable. 
       SUMMARY 
       [0010]    The present disclosure is directed generally to methods for the treatment of intervertebral discs. In particular, according to one aspect of the present disclosure, a method for relieving pain associated with an intervertebral disc having a disc nucleus pulposus and an outer annulus fibrosus surrounding the nucleus pulposus, is provided. 
         [0011]    The method includes the steps of providing an elongated thermal or electromagnetic probe member. The probe member has proximal and distal ends and defines a longitudinal axis. The probe member further includes a flexible guidable region adjacent the distal end thereof. 
         [0012]    The method further includes the step of introducing the flexible guidable region of the probe into the annulus fibrosus of the intervertebral disc. Preferably, the flexible guidable region of the probe is introduced at a location which is in relative close proximity to the region of intervertebral disc to be thermally or electromagnetically treated. The flexible guidable region of the probe is capable of bending to follow a generally arcuate path through the annulus fibrosus without entering the nucleus pulposus. Desirably, the step of introducing includes positioning the flexible guidable region of the probe adjacent the region of the intervertebral disc to be treated. 
         [0013]    The method further includes the step of supplying thermal or electromagnetic energy, from an energy source, to heat or induce an electromagnetic field adjacent to the annulus fibrosus sufficient to produce a thermal or electromagnetic effect on the intervertebral disc. 
         [0014]    The method may further include the step of positioning a cannula adjacent the region of the intervertebral disc to be treated; and passing the flexible guidable region of the probe through a lumen of the cannula. 
         [0015]    It is envisioned that the cannula may include an arcuate portion adjacent a distal end thereof. Accordingly, during the step of introducing the flexible guidable region of the probe, the arcuate cannula portion may guide the flexible guidable region of the probe adjacent to the region to be treated. 
         [0016]    The method may further include the step of angulating the arcuate portion of the cannula to a desired orientation within the intervertebral disc. 
         [0017]    The method may still further include the step of monitoring impedance of tissue to detect variations in tissue-type to thereby facilitate positioning of the flexible guidable region of the probe. 
         [0018]    The method further includes the steps of increasing an amplitude of thermal or electromagnetic energy supplied to the probe until indications of effect on the intervertebral disc are obtained; and noting the amplitude at which the indications of effect of the intervertebral disc are obtained. 
         [0019]    Desirably, when the indications of effect of the intervertebral disc are obtained for amplitudes below about 0.75 volts, thermal energy at about 60° C. is applied. When the indications of effect of the intervertebral disc are obtained for amplitudes between about 0.75 volts and 1.25 volts, thermal energy at about 65° C. is applied. When the indications of effect of the intervertebral disc are obtained for amplitudes above about 1.25 volts, thermal energy at about 70° C. is applied. 
         [0020]    According to another aspect of the present disclosure, the method includes the steps of introducing a thermal or electromagnetic transmitting element of a thermal probe into the intervertebral disc, at a location in close proximity to the region of the intervertebral disc to be treated; and supplying thermal or electromagnetic energy from an energy source to the thermal or electromagnetic transmitting element to produce a thermal or electromagnetic effect on the intervertebral disc. 
         [0021]    Desirably, the probe includes a flexible guidable region. Accordingly, the method further includes the step of advancing the probe whereby the flexible guidable region of the probe follows a generally arcuate path. The step of advancing the probe may include passing the flexible guidable region along an arcuate path defined by natural striata of the annulus fibrosus. The step of advancing the probe may include extending the flexible guidable region across the region of the intervertebral disc to be treated. 
         [0022]    Moreover, the present disclosure relates to methods of using neural stimulation during nucleoplasty procedures for confirming the placement of a probe in a nucleus pulposus of an intervertebral disc and methods of performing nucleoplasty. 
         [0023]    According to an aspect of the present disclosure, a method for performing of nucleoplasty is provided. The method includes the step of providing an elongated thermal or electromagnetic probe having a proximal end, a distal end and having a guidable region adjacent the distal end thereof. The method further includes the steps of introducing the guidable region of the probe into a nucleus of an intervertebral disc, activating the probe, increasing the amplitude of the activated probe until an effect is obtained on the nervous system, and noting the amplitude at which the effect on the nervous system is observed. The method further includes the step of re-activating the probe to treat the nucleus, wherein the probe is activateable up to the amplitude that is dictated by a threshold amplitude of nervous system stimulation. 
         [0024]    According to another aspect of the present disclosure, a method of performing a nucleoplasty is provided and includes the steps of providing a generator, and providing an apparatus for performing the nucleoplasty. The apparatus includes an introducer cannula having at least an electrically conductive distal end, a stylet selectively positionable in the introducer cannula to occlude the introducer cannula during introduction of the introducer cannula into an intervertebral disc, and an elongated thermal or electromagnetic probe having a proximal end, a distal end and having a guidable region adjacent the distal end thereof. 
         [0025]    The method further includes the steps of introducing the introducer cannula having the stylet positioned therewithin into the intervertebral disc, monitoring an impedance of tissue adjacent the distal end of the introducer cannula to determine when the distal end of the introducer cannula is positioned within the nucleus, and removing the stylet from the introducer cannula prior to introduction of the guidable region of the probe into the introducer cannula. 
         [0026]    The method still further includes the steps of introducing the probe through the introducer cannula such that the guidable region thereof extends from the distal end of the introducer cannula and into the nucleus, activating the probe, increasing the amplitude of the activated probe until an effect is obtained in the nervous system, noting the amplitude at which the effect on the nervous system is observed, and re-activating the probe to treat the nucleus, wherein the probe is activateable up to the amplitude that is dictated by the threshold amplitude of nervous system stimulation. 
         [0027]    According to yet another aspect of the present disclosure, a method of using neural stimulation during nucleoplasty procedures for confirming the placement of a probe in a nucleus of an intervertebral disc is provided. The method includes the steps of providing a generator; and providing an apparatus for performing a nucleoplasty. The apparatus includes an introducer cannula having at least an electrically conductive distal end, wherein the distal end of the introducer cannula is electrically connected to the generator. 
         [0028]    The method further includes the steps of introducing the introducer cannula into the intervertebral disc, and monitoring an impedance of tissue adjacent the distal end of the introducer cannula to determine when the distal end of the introducer cannula is positioned within the nucleus. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    The features of the apparatus and method of the present disclosure will become more readily apparent and may be better understood by referring to the following detailed description of illustrative embodiments of the present disclosure, taken in conjunction with the accompanying drawings, wherein: 
           [0030]      FIG. 1  is a cross-sectional view of an intervertebral disc with a portion of an intervertebral apparatus inserted therein according to a prior art method; 
           [0031]      FIG. 2  is a cross-sectional plan view of a cervical disc and vertebra; 
           [0032]      FIG. 3  is a side view of a portion of the spine; 
           [0033]      FIG. 4  is an enlarged side view of the area indicated as “4” of the spine of  FIG. 3 ; 
           [0034]      FIG. 5  is a schematic illustration of an intervertebral apparatus, in a disassembled condition, depicting an insertion cannula, a thermal or EMF probe and associated auxiliary electronic components; 
           [0035]      FIG. 6  is a cross-sectional plan view of an intervertebral disc with a portion of an intervertebral apparatus inserted therein according to a method of the present disclosure; 
           [0036]      FIG. 7  is a cross-sectional plan view of an intervertebral disc with a portion of an intervertebral apparatus inserted therein according to another method or another step of the present disclosure; 
           [0037]      FIG. 8  is a cross-sectional plan view of an intervertebral disc with a portion of an intervertebral apparatus inserted therein according to yet another method or another step of the present disclosure; 
           [0038]      FIG. 9  is a cross-sectional plan view of an intervertebral disc with a portion of an intervertebral apparatus inserted therein according to still another method or another step of the present disclosure; and 
           [0039]      FIGS. 10-11  illustrate a method, in accordance with the present disclosure, of using the intervertebral apparatus of  FIG. 5  during a nucleoplasty procedure in order to confirm the placement of an electrode in a nucleus pulposus of an intervertebral disc. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0040]    The present disclosure provides for an alternate and/or improved method of positioning an apparatus (e.g., a thermal probe) in an intervertebral disc targeted for treatment of intervertebral disc disorders. Such disorders include but are not limited to degenerative discs with (i) localized tears or fissures in the annulus fibrosus, (ii) localized disc herniations with contained extrusions, and (iii) chronic, circumferential bulges. 
         [0041]    It will be readily apparent to a person skilled in the art that the apparatus and method of use of the apparatus may be used to treat/destroy body tissue in any body cavity or tissue locations that are accessible by percutaneous or endoscopic catheters or open surgical techniques, and is not limited to the disc area. Application of the apparatus and method in all of these organs and tissues are intended to be included within the scope of the present disclosure. 
         [0042]    In the drawings and in the following description, the term “proximal”, as is traditional, will refer to the end of the apparatus, or component thereof, which is closest to the operator, and the term “distal” will refer to the end of the apparatus, or component thereof, which is more remote or further from the operator. 
         [0043]    Prior to a detailed discussion of the apparatus and method according to the present disclosure, a brief overview of the anatomy of a typical cervical vertebra is presented. Accordingly, as seen in  FIGS. 1-4 , a typical cervical vertebra includes a spinal column “SC;” a dorsal root of spinal nerve “SN;” an intervertebral disc “D” that includes an annulus fibrosus “A” and a nucleus pulposus “N” disposed within annulus fibrosus “A”. Annulus fibrosus “A” includes a tough fibrous material which is arranged to define a plurality of annular cartilaginous rings “R” forming the natural striata of annulus fibrosus “A”. Nucleus pulposus “N” is made up primarily of an amorphous gel having a softer consistency than annulus fibrosus “A”. Nucleus pulposus “N” usually contains 70%-90% water by weight and mechanically functions similar to an incompressible hydrostatic material. The juncture or transition area of annulus fibrosus “A” and nucleus pulposus “N” generally defines, for discussion purposes, an inner wall “W” of annulus fibrosus “A”. Disc cortex “C” surrounds annulus fibrosus “A”. Posterior, anterior, and lateral aspects of intervertebral disc “D” are identified as “P”, “AN” and “L”, respectively, with the opposed posterior-lateral aspects identified as “PL”. In  FIG. 2 , a portion of intervertebral disc “D” has been cut away so that half of the vertebral body may be seen. 
         [0044]    When mechanical stress is put upon a disc or when a disc degenerates with age, fissures, illustrated by cracks “F” in  FIG. 6 , may occur in the posterior or posterior/lateral portions of disc “D”. Problems with nerves, fissures “F” and degenerative discs may give rise to various patient problems, such as back or leg pain originating from the irritation or occurrence of these abnormalities. Moreover, these conditions may ultimately result in conditions such as bulging or herniated discs. By heating and/or using electromagnetic field (EMF) therapy on intervertebral disc “D”, preferably, annulus fibrosus “A” in posterior “P” or posterior-lateral “PL” portions, will result in denervation of nerves and/or alterations and thermal ablation of disc structures, which will in turn produce alleviation of pain and healing of the disc. Thus, it is desirable to have a practical and efficient method of placing a thermal or electromagnetic probe in posterior “P” and/or posterior-lateral “PL” portion of disc “D” where these neural and aberrant structures occur for the relief of pain and other disc related problems. 
         [0045]    With reference to  FIG. 5 , an apparatus according to the present disclosure is shown and is generally designated as  100 . Apparatus  100  includes outer insertion or introducer cannula  102 , thermal or EMF probe  104  which is positionable within cannula  102 , and a power source  106  which is connected to thermal probe  104 . Introducer cannula  102  preferably includes a rigid tubular shaft  108  defining a longitudinal axis “X” and having a rigid curved or arcuate portion  110  adjacent it distal end, angularly offset with respect to the longitudinal “X” axis at an angle ranging from about 15 to about 45°, preferably, about 23°. Shaft  108  is preferably composed of a conductive material such as stainless steel or other suitable composition and is insulated with insulation along most of its length as indicated by the hatching of  FIG. 5 . Alternatively, shaft  108  may be fabricated from a suitable polymeric material and formed by conventional injection molding techniques. The distal end portion  112  of shaft  108  may be left uninsulated or exposed to permit electrical connection (e.g., for impedance measuring, etc.) to or contact with the tissue as cannula  102  is placed in the tissue. Alternatively, exposed portion  112  may be connected to power source  106  to heat stimulate or micro-thermal generate the tissue to facilitate passage through the tissue. 
         [0046]    An extreme distal tip  114  of shaft  108  is preferably sharpened to facilitate penetration into the disc tissue, i.e., through the bone of the cortex “C” and into annulus fibrosus “A”. A handle or housing  116  is connected to the proximal end of cannula shaft  108  to facilitate manipulation of cannula  102 . Handle  116  may include an index marker  118  to indicate the direction of arcuate portion  110  of cannula  102  such that when thermal or EMF probe  104  is introduced within cannula  102 , the surgeon may determine in which azimuthal rotational direction the curve is oriented. 
         [0047]    Cannula shaft  108  may have a diameter ranging from a fraction of a millimeter to several millimeters and a length of a few centimeters up to about 20 centimeters or more. Alternatively, cannula shaft  108  may be fabricated from an MRI compatible material, including cobalt alloys, titanium, copper, nitinol, etc. Arcuate portion  110  of cannula  102  may assume a variety of angular orientations depending on the surgical procedure to be performed. In an embodiment for thermal or EMF therapy of the intervertebral disc, arcuate portion  110  is arranged such that thermal or EMF probe  104  is generally delivered from cannula  102  in a substantially orthogonal relation to the longitudinal “X” axis. 
         [0048]    Power source or generator  106  may be, for example, a radiofrequency generator providing energy at frequencies between several kilohertz to several hundred megahertz. Power source  106  may have a power output ranging from several watts to several hundred watts, depending on clinical need. Power source  106  may have control devices to increase or modulate power output as well as readout and display devices to monitor energy parameters such as voltage, current, power, frequency, temperature impedance  109 , etc., as appreciated by one skilled in the art. Other types of power sources are also contemplated, e.g., including resistive heating units, laser sources, or microwave generators. 
         [0049]    Apparatus  100  may preferably include an imaging system (not shown) for potentially monitoring, controlling or verifying the positioning of cannula  102  and/or thermal probe  104 . Imaging systems contemplated include X-ray machines, fluoroscopic machines or an ultrasonic, CT, MRI, PET, or other imaging devices. Several of these devices have conjugate elements (not shown), on the opposite side of the patient&#39;s body, to provide imaging data. For example, if the imaging system is an X-ray machine, the conjugate element may be a detection device, such as an X-ray film, digital X-ray detector, fluoroscopic device, etc. Use of imaging machines to monitor percutaneously placed electrodes into tissue is commonly practiced in the surgical field. 
         [0050]    With continued reference to  FIG. 5 , apparatus  100  may further include a stylet  148  which is to be used in conjunction with cannula  102 . Stylet  148  is positionable within the lumen of cannula  102  and preferably occludes the front opening of cannula  102  to prevent entry of tissue, fluids, etc., during introduction of cannula  102  within intervertebral disc “D”. Stylet  148  may include a proximally positioned hub  150  which mates with handle  116  of cannula  102  to lock the components together during insertion. Such locking mechanisms are appreciated by one skilled in the art. 
         [0051]    An impedance monitor  152  may be connected, as shown by connection  154 , to stylet  148  and therefore communicates electrically with the exposed portion  112  of cannula  102  into which stylet  148  is introduced to monitor impedance of the tissue adjacent the distal end of cannula  102 . Alternatively, connection of the impedance monitor may be made directly to the shaft of cannula  102  whereby impedance measurements are effectuated through the exposed distal end of cannula  102 . Once the combination of stylet  148  and cannula  102  are inserted into the body, impedance monitoring assists in determining the position of cannula tip  112  with respect to the patient&#39;s skin, cortex “C” of disc “D”, annulus fibrosus “A”, and/or nucleus “N” of disc “D”. These regions will have different impedance levels which are readily quantifiable. 
         [0052]    For example, for a fully insulated electrode or cannula with an exposed area of a few square millimeters at the cannula end, the impedance will change significantly from the position of the tip near to or contacting cortex “C” of disc “D” to the region where the tip is within annulus fibrosus “A” and further where the tip is within nucleus “N” of disc “D”. Differences of impedance may range from a few hundred ohms outside disc “D”, to 200 to 300 ohms in annulus fibrosus “A”, to approximately 100 to 200 ohms in nucleus “N”. This variation may be detected by the surgeon by visualizing impedance on meters or by hearing an audio tone whose frequency is proportional to impedance. Such a tone may be generated by monitor  109 . In this way, an impedance means is provided for detecting placement of the curved cannula within disc “D”. Thus, for example, in an application where the EMF probe  104  is to be inserted between adjacent layers of annular tissue, undesired penetration of the EMF probe  104  and tip portion  112  of cannula  102 , through the inner wall “W” of annulus fibrosus “A” and into nucleus pulposus “N”, can be detected via the impedance monitoring means. 
         [0053]    Stylet  148  can be made from a rigid metal tubing with either a permanent bend  156  at its distal end to correspond to the curvature of arcuate portion  112  of cannula  102  or may be a straight guide wire to adapt to the curvature of cannula  102  when it is inserted within cannula  102 . Hubs  116 ,  120 ,  150 , and connector  154  can take various forms including luer hubs, plug-in-jack-type connections, integral cables, etc. 
         [0054]    With reference now to  FIGS. 5 and 6 , use of apparatus  100 , in accordance with a preferred procedure, for thermal treatment of an intervertebral disc, will now be discussed. With reference to  FIG. 6 , the targeted intervertebral disc “D” is identified during a pre-operative phase of the surgery. Intervertebral disc “D” defines a “Y” plane extending between a posterior rand an anterior side of disc “D”, and an “X” plane, perpendicular to the “Y” plane, extending between lateral sides of the intervertebral disc “D,” such that the intervertebral disc “D” defines four substantially equal quadrants (see  FIGS. 6-9 , for example), wherein the posterior “P”, anterior “A”, and lateral “L” aspects (e.g. posterior-lateral “PL”) are disposed within one or more of the quadrants. Access to the intervertebral disc area is then ascertained, preferably, through percutaneous techniques or, less desirably, open surgical techniques. 
         [0055]    Cannula  102 , with stylet  148  positioned and secured therein, is introduced within intervertebral disc “D”, preferably from a posterior or posterior-lateral location, most preferably, a location which is in relative close proximity to, preferably adjacent to, the region of intervertebral disc “D” to be thermally or electromagnetically treated (e.g., fissure(s) “F”), as seen in  FIG. 6 . It is envisioned that cannula  102  may be utilized without stylet  148 . 
         [0056]    Impedance monitoring is desirably utilized to determine the position of cannula tip  114  with respect to the patient&#39;s skin, cortex “C” of disc “D”, annulus fibrosus “A” and/or nucleus “N” of disc “D”. As discussed above, these regions have different and quantifiable impedance levels thereby providing an indication to the user of the position of cannula tip  114  in the tissue. Monitoring of the location of cannula  102  may also be confirmed with an imaging system (not shown). In a preferred procedure, cannula tip  114  of cannula  102  is positioned within annulus fibrosus “A” of intervertebral disc “D” at a posterior lateral “PL” location of disc “D” without penetrating through inner wall “W” and into nucleus “N”. As appreciated, a sharpened cannula tip  114  facilitates entry into annulus fibrosus “A”. 
         [0057]    Thereafter, cannula  102  is angulated to position arcuate end portion  110  of cannula  102  at the desired orientation within annulus fibrosus “A”. Confirmation of the angular orientation of arcuate end portion  110  of cannula  102  is made through location of index marker  118  of cannula  102 . In one preferred orientation, arcuate end portion  110  is arranged to deliver thermal probe  104  within the posterior section of the intervertebral disc “D”. 
         [0058]    According to another method, as seen in  FIG. 7 , cannula  102  may be angulated to position arcuate end portion  110  of cannula  102  in another desired orientation within annulus fibrosus “A”. In this other desired orientation, arcuate end portion  110  is arranged to deliver thermal probe  104  within the posterior-lateral “PL” section of intervertebral disc “D”. When so positioned, as will be described in greater detail below, advancement of thermal probe  104  through cannula  102  results in placement of guidable region  128  in the posterior-lateral “PL” section of intervertebral disc “D”. 
         [0059]    According to yet another method, as seen in  FIG. 8 , cannula  102  may be positioned so as to place arcuate end portion  110  of cannula  102  in yet another desired location and orientation within annulus fibrosus “A”. In the other desired orientation and location, arcuate end portion  110  is positioned in close proximity to inner wall “W” of annulus fibrosus “A”. When so positioned, as will be described in greater detail below, advancement of thermal probe  104  through cannula  102  results in placement of guidable region  128  in the nucleus “N” of the intervertebral disc “D”. 
         [0060]    Stylet  148  is then removed from cannula  102 . Thermal or EMF probe  104  is positioned within the internal lumen of cannula  102  and advanced through cannula  102 . Preferably, the pre-bent orientation of guidable region  128  is arranged to coincide with the arcuate end portion  110  of cannula  102 . Confirmation of this orientation may be made with the location of the indexing element  121  of handle  120  (see  FIG. 5 ). Preferably, arcuate end portion  110  is angulated to directly access the posterior-lateral “PL” section of annulus fibrosus “A” without entering nucleus “N”. Thermal or EMF probe  104  is thereafter advanced to position guidable region  128  thereof medially through the posterior “P” section of annulus fibrosus “A”, desirably adjacent and/or across fissure(s) “F”, as seen in  FIG. 6 . Guidable region  128  of probe  104  is extended by approximately 1.5 cm or less from the distal end of cannula  102 . 
         [0061]    Alternatively or additionally, as seen in the method of  FIG. 7 , advancement of thermal or EMP probe  104  results in placement of guidable region  128  thereof laterally along the posterior-lateral “PL” section of annulus fibrosus “A” (e.g., in a direction away from fissure “F”. It is further envisioned, as seen in the method of  FIG. 8 , that thermal or EMF probe  104  may alternatively or additionally be advanced so as to place guidable region  128  thereof into nucleus “N” of intervertebral disc “D”. 
         [0062]    As seen in  FIG. 9 , should disc “D” have bilateral fissures “F 1 , F 2 ” then guidable region  128  of probe  104  may be extended through the posterior “P” section into the contralateral side of the disc “D” in order to place probe  104  adjacent to the secondary fissure “F 2 ”. Confirmation of the orientation of arcuate end portion  110  is provided through an index pin or marker adjacent to cannula  102  and can be also monitored through the imaging system. 
         [0063]    Following the confirmation that guidable region  128  of probe  104  is properly placed, “Simulation Mode” is selected on power source  106 . First, the “Sensory Range” is activated and the amplitude of the simulation is increased until indications of effect and/or stimulation, of the region to be treated, are obtained. The amplitude at which the indications of effect and/or stimulations are obtained, of the region to be treated, is then noted. In the event that the “Sensory Range” does not provide a sufficient effect, the “Motor Range” is activated and the amplitude is increased. The noted amplitude dictates the temperature which is selected on the “Automatic Temperature Control” for the treatment of disc “D”. Accordingly, the heating cycle for each position of guidable region  128  of probe  104  is dictated by the threshold of the stimulations. For example, if stimulation of the region to be treated occurs below about 0.75V, then a temperature of approximately 60° C. is applied. If, for example, stimulation of the region to be treated occurs between about 0.75V and 1.25V, then a temperature of approximately 65° C. is applied. If, for example, stimulation of the region to be treated occurs above about 1.25V, then a temperature of approximately 70° C. is applied. 
         [0064]    Once guidable region  128  of probe  104  is positioned within annulus fibrosus “A” as desired, power source  106  is activated whereby thermal or EMF probe  104  delivers thermal energy and/or creates an electromagnetic field through guidable region  128  adjacent intervertebral disc “D” to produce the thermal and/or EMF therapy in accordance with the present disclosure. Appropriate amounts of power, current or thermal heat may be monitored from the external power source  106  and delivered for a certain amount of time as determined appropriate for clinical needs. 
         [0065]    For example, if denervation of nerves surrounding disc “D” is the objective, the tissue adjacent the probe end is heated to a temperature of from about 45° C. to about 60° C. If heating of fissures “F” in disc “D” is the surgical objective, the temperature in the tissue is raised to about 60-75° C. As appreciated, the degree of extension of guidable region  128  from cannula  102  controls the volume of disc tissue heated by probe  104 . A thermal sensor (not shown), provided on thermal or EMF probe  104  can provide information concerning the temperature of tissue adjacent the distal end. In an embodiment, the impedance means associated with cannula  102  can provide impedance measurements of the tissue thereby providing an indication of the degree of dessication, power rise, or charring, that may be taking place near tip  134  of thermal probe  104 . This indicates the effectiveness of the treatment and guards against unsafe contraindications of the therapy. 
         [0066]    Following thermal treatment at this location, cannula  102  is repositioned so that guidable region  128  of thermal probe  104  is guided laterally in annulus fibrosus “A” toward the posterior-lateral “PL” section. Again, following the confirmation that guidable region  128  of probe  104  is properly placed, “Simulation Mode” is selected on power source  106  and the heating cycle is dictated by the threshold of the stimulations. On completion of thermal treatment in this position, cannula  102  is once again adjusted or repositioned so that guidable region  128  of thermal probe  104  may be placed within nucleus “N” of disc “D”. A temperature approximately equal to the boiling point of the nucleus “N” and up to approximately 90° C. is applied if stimulation occurs above about 1.5V when the guidable region  128  of thermal probe  104  is placed within nucleus “N”. 
         [0067]    The use of apparatus  100  in accordance with an alternate procedure for thermal treatment of an intervertebral disc “D,” namely decompression or nucleoplasty, will now be discussed. With reference to  FIGS. 10-11  the targeted intervertebral disc “D” is identified during a pre-operative phase of the surgery. Access to the intervertebral disc area is then ascertained, preferably, through percutaneous techniques or, less desirably, through open surgical techniques. 
         [0068]    As seen in  FIG. 10 , cannula  102 , with stylet  148  positioned and secured therein, is introduced within intervertebral disc “D”, preferably from a posterior or posterior-lateral location. During introduction of the assembled components, the impedance of the tissue adjacent distal end portion  114  of cannula  102  is monitored through cannula  102  or alternatively via impedance monitor  152 . 
         [0069]    Impedance monitoring may be utilized to determine the position of distal tip  112  of cannula  102  with respect to the patient&#39;s skin, the cortex “C” of the disc, the annulus “A” and/or the nucleus “N” of the disc. As discussed above, these regions have different and quantifiable impedance levels, thereby providing an indication to the user of the position of the distal tip  112  of cannula  102  in the tissue. Monitoring of the location of cannula  102  may also be confirmed with a suitable imaging system (not shown). In a preferred procedure, distal tip  112  of cannula  102  is positioned within the nucleus “N” of intervertebral disc “D”. As appreciated, sharpened distal tip  112  of cannula  102  facilitates entry thereof into the nucleus “N”. 
         [0070]    Upon confirmation of placement of distal tip  112  of cannula  102  in the nucleus “N,” as by the correct impedance reading and/or by real-time imaging through fluoroscopy, stylet  148  is removed from cannula  102 . Following removal of stylet  148  from cannula  102 , as seen in  FIG. 11 , thermal or EMF probe  104  is positioned within the internal lumen of cannula  102  and advanced through cannula  102 . Probe  104  may be either monopolar or bipolar. 
         [0071]    Probe  104  is advanced to at least partially expose guidable region  128  of probe  104  from distal tip  112  of cannula  102 . The degree of extension of guidable region  128  beyond distal tip  112  of cannula  102  may be indicated by distance of index markings  136  on the shaft of probe  104  and confirmed by the imaging system. Following the confirmation that probe  104  is properly positioned within the nucleus “N”, a “stimulate mode” is activated on power source or generator  106 . The “stimulate mode” has an adjustable intensity. In one embodiment, the “stimulate mode” is divided into a pair of intensity ranges, a “neural stimulate mode” and a “muscle stimulate mode”. The “neural stimulate mode” may have an intensity of from about 0.1 volts to about 1.0 volts. The “muscle stimulate mode” may have an intensity of from about 1.0 volts to about 10.0 volts. The outputs of the intensities are transmitted in a pulse waveform. 
         [0072]    According to the present disclosure, the amplitude of the “stimulation mode” is increased until indications of effect on the nervous system are obtained and/or observed. The indications of effect are either reported to the surgeon by the patient as a feeling of a tingle or the like, or are directly observed by the surgeon as a muscle contraction or the like. The maximum level to which the amplitude of probe  104  may be increased is up to approximately 10.0 volts. Indications of effect on the nervous system are transmitted to the spinal column “SC” and/or the spinal nerve “SN”. The amplitude at which an effect is elicited may be more or less depending on the position and/or placement of probe  104  relative to critical nerve tissue, such as the spinal column “SC” or nerve roots “SN”. If the initial “stimulate mode” does not provide an effect on the nervous system, the amplitude is increased and the “simulate mode” is once again activated. 
         [0073]    The amplitude at which a sufficient effect on the nervous system is achieved is noted and/or otherwise saved in power source  106 . The noted amplitude indicates the proximity to critical nerve tissue and dictates and/or otherwise determines the temperature to be selected on power source  106  for the decompression treatment of disc “D”. 
         [0074]    Following notation of the amplitude, first, the “nerve stimulate mode” is activated and, if no reaction is noted, then the “motor stimulate mode” is activated on power source  106 . In other words, once the amplitude is determined, power source  106  is activated whereby thermal or EMF probe  104  delivers thermal energy and/or creates an electromagnetic field through guidable region  128  to produce the thermal and/or EMF therapy necessary and/or desired. Desirably, a treatment table or the like may be provided which cross-references amplitudes and temperatures for every possible probe  104  exposure. Appropriate amounts of power, current or thermal heat may be monitored from the external power source  106  and delivered for a certain amount of time as determined appropriate for clinical needs. 
         [0075]    As appreciated, the degree of extension of guidable region  128  from cannula  102  controls the volume of disc tissue or nucleus tissue heated by probe  104 . Thermal sensor  138  of thermal or EMF probe  104  may provide information concerning the temperature of tissue adjacent the distal end. The impedance means associated with e.g., EMF probe  104 , may provide impedance measurements of the tissue thereby providing an indication of the degree of desiccation, power rise, etc. that may be taking place near the distal end of probe  104 . This indicates the effectiveness of the treatment and guards against unsafe contraindications of the therapy. 
         [0076]    The apparatus and method of the present disclosure provides significant advantages over the prior art. 
         [0077]    Cannula  102  and thermal or EMF probe  104  permits the probe to be inserted through the body, preferably, on the same side as the tear or fissure “F” formed in annulus fibrosus “A” of disc “D”. The present method reduces the distance guidable probe  128  must be steered through annulus fibrosus “A”. 
         [0078]    Additionally, the site of injury and/or the region to be treated receives a higher level of directed RF energy. As a result, the likelihood of effective treatment of the site of injury and/or the region to be treated is increased. This increased effective treatment may include, and is not limited to, for example, multiple RF treatments that ablate the nerve fibers that have grown into the site of injury, as well as the nerve fibers in the outer annulus fibrosus “A” that may be the source of discogenic pain. The increased effective treatment may also include directed RE energy denaturing of the biochemical constituents of the nucleus pulposus to thereby reduce their contribution as a source of pain. Additionally, the directed RF energy may also create a local area of reduced pressure and higher viscosity in the nucleus “N”, in the immediate vicinity of the fissure(s) to thereby reduce the likelihood of further extravasations of nuclear material. 
         [0079]    In addition, spinal cord and spinal nerve roots are critical tissues that must be spared during thermal treatments. Accordingly, the present method and/or procedure enables a surgeon to identify if these critical structures are in jeopardy of being injured by the procedure. 
         [0080]    A further advantage of the present apparatus and method is that by using a curved introduction cannula, a more efficacious direction of the probe may be achieved in the difficult lumbar or lumbar-sacral intervertebral discs. In these approaches, nearby heavy bone structure, such as the iliac crest, can often obscure a placement of a curved probe parallel to the end plates or bony margins of adjacent intervertebral discs. By appropriate angulation and rotation of a curved cannula, the extension of a thermal probe, parallel to the so-called end plates of the intervertebral discs, is made possible with minimal repositioning and manipulation of the introduction cannula. 
         [0081]    A further advantage of the present apparatus and method is that it enables simple, minimally-invasive, percutaneous, out-patient treatment of intradiscal pain without the need for open surgery as for example discectomies or spinal stabilization using plates, screws, and other instrumentation hardware. A further advantage of the present disclosure is that it is simple to use and relatively economical. Compared to open surgery, the treatment of the disc by percutaneous electrode placement represents only a procedure of a few hours with minimal hospitalization, and with minimal morbitity to the patient. On the other hand, open surgical procedures often require full anesthetic, extensive operating room time, and longer hospital and home convalescence. 
         [0082]    While the above description contains many specific examples, these specifics should not be construed as limitations on the scope of the disclosure, but merely as exemplifications of preferred embodiments thereof. Those skilled in the art will envision many other possible variations that are within the scope and spirit of the disclosure as defined by the claims appended hereto.