Abstract:
A method of controllably heating the annulus of an intervertebral disc is disclosed. The method comprises the steps of forming an access channel through the annulus of an intervertebral disc while avoiding the nucleus of the intervertebral disc, inserting a light-emitting diffuser into the annulus, and activating the light-emitting diffuser to emit diffuse light while maintaining the light-emitting diffuser within the access channel to raise the temperature of the annulus to a value sufficient to cause a change in the characteristics of the annulus.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application Serial No. No. 60/210756, filed Jun. 12, 2000.  
         [0002]    This application is related to the copending U.S. patent application Ser. No. ______, filed Jun. XX, 2001 [Attorney Docket No. IND0051], which is hereby incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0003]    The present invention relates, in general, to a method of treating intervertebral discs to relieve back pain and, more particularly, a method of treating an intervertebral disc by using a light energy diffuser placed within the annulus of an intervertebral disc, while avoiding the nucleus of the intervertebral disc, and using the diffuser to heat a damaged portion of an annulus of the intervertebral disc by diffusing light energy directly into the annulus of the intervertebral disc.  
         BACKGROUND OF THE INVENTION  
         [0004]    Degenerative disc disorders are difficult to treat. The normal pathway for treatment of lower back pain starts with a number of minimally invasive treatments including medications and exercise. Spinal surgery, such as spinal fusion or ablation of the nucleus, can also be used, but such surgeries are generally avoided because they are very invasive. A less invasive procedure is percutaneously applying heat to the annulus of the intervertebral disc.  
           [0005]    Damage to the intervertebral disc in the spine is the main cause of lower back pain. The intervertebral disc, sometimes called a spinal disc or a disc, is a capsule with an annulus, comprising collagen, surrounding an inner volume called the nucleus. The nucleus contains a gel-like material. Damage to the annulus triggers the body to attempt to repair the injury. The repair attempt results in blood vessels and nerves growing into the damaged area of the annulus. It is believed that these new nerve endings are the source of “discogenic pain” and low back pain. Damage to the annulus also can result in weakening and bulging of the intervertebral disc. If the bulging puts pressure on nerve roots from the spinal cord the result is pain and nerve dysfunction.  
           [0006]    It is well known that collagen responds to heat by shrinking and stiffening. In a damaged intervertebral disc where the damage has resulted in a bulge, heating the annulus to shrink the collagen in the annulus can help reduce the bulge. Heating the annulus to stiffen the collagen is also beneficial because the stiffer annulus reduces excessive movement of the spine. In addition, the heat applied to the annulus to shrink the collagen is beneficial because it damages or destroys nerve endings that may have grown into the damaged annulus thereby reducing the ability of the nerves to transmit pain. The combination of shrinking the collagen in the annulus and damaging or destroying the unwanted nerve endings is thought to be beneficial in reducing back pain.  
           [0007]    Physicians have treated intervertebral disc pain utilizing radiofrequency current and lasers to damage nerve endings that have grown into the annulus. U.S. Pat. No. 5,433,739 to Sluijter et al describes a method of treating disc pain by utilizing radiofrequency current to heat the nucleus of an intervertebral disc. The nucleus is heated to a higher temperature than the annulus to transfer heat to the annulus of the intervertebral disc to raise the temperature of the intervertebral disc to a level that damages unwanted ingrown nerve endings. In U.S. Pat. No. 5,571,147, Sluijter et al describe a method of using laser light for heating the nucleus of an intervertebral disc.  
           [0008]    Physicians have also treated disc pain utilizing lasers to ablate or vaporize the nucleus of an intervertebral disc. U.S. Pat. No. 5,958,008 to Daikuzono describes using a laser to vaporize the nucleus of an intervertebral disc.  
           [0009]    Physicians have also treated disc pain by utilizing an electrically heated wire placed through the nucleus of an intervertebral disc to heat the annulus of the intervertebral disc to a temperature sufficient to cause the collagen in the annulus to shrink. The wire, which is heated by resistive heating, transfers heat by conduction to surrounding tissues. U.S. Pat. No. 6,122,549 to Sharkey et al describes a method to treat disc pain utilizing thermal resistive electric heating.  
           [0010]    Ablating the nucleus or heating the annulus by inserting devices through the nucleus necessitates disturbing the tissues of the nucleus. It would be less invasive to avoid inserting devices into the nucleus by directly entering a damaged portion of the annulus from the outside of the annulus. Devices that heat by diffuse light energy use radiation to cause faster heat transfer and lower heating times than conduction. The faster heat transfer can be used to controllably heat a damaged zone of the annulus while maintaining adjacent tissues, such as the nucleus, at a temperature below that which would cause degradation. It would, therefore, be advantageous to develop a method of controllably heating an annulus of an intervertebral disc by diffusing light energy directly into the annulus, avoiding the nucleus, to avoid disturbing tissues such as the nucleus. It would further be advantageous to develop a method of controllably diffusing light energy directly into the intervertebral disc utilizing optical temperature feedback and control. It would further be advantageous to controllably and directly heat a portion of the annulus of an intervertebral disc utilizing light energy to avoid damaging a healthy portion of the spine.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention is directed to a method of heating the annulus of an intervertebral disc by inserting a light diffuser directly into the annulus of an intervertebral disc from outside the disc while avoiding the nucleus. The present invention further includes a method of controllably shrinking collagen in the annulus of a intervertebral disc using a diffuse light source placed within the annulus to emit diffuse light energy directly into the annulus, optically measuring the temperature of the heated tissue, and adjusting light intensity based on the measured temperature. In particular, in a method according to the present invention, an optical fiber including a diffuser is placed into the annulus of an intervertebral disc percutaneously through a small diameter piercing needle or trocar. The fiber&#39;s diffuser is introduced from outside the annulus while avoiding the nucleus of the intervertebral disc. The fiber&#39;s diffuser is advanced to an area within the annulus needing heat to shrink collagen or to damage nerve endings. The light generator, such as a laser, is programmed to deliver light energy to raise the temperature of a region of the annulus tissue to a predetermined temperature for a predetermined length of time. The temperature can be, for example, a temperature sufficient to produce nerve damage of ingrown unwanted nerve endings in the annulus of an intervertebral disc or a temperature sufficient to produce shrinkage of collagen in the annulus of an intervertebral disc. In an optical fiber and light generator useful for an embodiment of the present invention, temperature monitoring of tissue near the optical fiber can be accomplished using fluorescent material placed within the optical fiber. The fluorescent material, when illuminated with a light in a wavelength emitted by the light generator, fluoresces with a light that decays in intensity with a time delay dependent upon the temperature of tissue near the material. Computerized control within the light generator monitors the returned fluorescent signal and controls power output and light intensity to control temperature of tissue near the optical fiber. A method according to the present invention further includes heating the annulus using an advantageous optical fiber that includes a continuous, unitary outer sleeve.  
           [0012]    Detailed illustrative embodiments of laser fibers for implementing the present invention are disclosed. However, it should be recognized that various alternate structural elements may occur to those skilled in the art, some of which may be different from those specific structural and functional details that are disclosed.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The novel features of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to organization and methods of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in conjunction with the accompanying drawings in which:  
         [0014]    [0014]FIG. 1 is an isometric view of a laser treatment system, including a laser and an optical fiber, which may be used in a method according to the present invention.  
         [0015]    [0015]FIG. 2 is an isometric view of the laser illustrated in FIG. 1 with the housing removed to expose interior elements including the optical bench and controller board.  
         [0016]    [0016]FIG. 3 is a cross-section view taken along the longitudinal axis of the distal end of one embodiment of an optical fiber illustrated in FIG. 1, including a diffuser.  
         [0017]    [0017]FIG. 4 is a cross-section view taken along  4 - 4  of FIG. 3 showing the interior of the diffuser portion of the optical fiber illustrated in FIG. 1 including abrasions on the inner circumference of the outer sleeve.  
         [0018]    [0018]FIG. 5 is a cross-section view taken along the longitudinal axis of the distal end of an alternate embodiment of the optical fiber illustrated in FIG. 1 including a diffuser incorporating a continuous, unitary outer sleeve.  
         [0019]    [0019]FIG. 6 is a block diagram of a laser treatment system, including one embodiment of a diffuser, which may be used in a method according to the present invention.  
         [0020]    [0020]FIG. 7 is a block diagram of a laser treatment system, including an alternate embodiment of a diffuser, which may be used in a method according to the present invention.  
         [0021]    [0021]FIG. 8 is a block diagram of an alternate embodiment of a laser treatment system, which may be used in a method according to the present invention.  
         [0022]    [0022]FIG. 9 is cross-section view of an embodiment of a diffuser, which may be used in a method according to the present invention, employing a spherical dispersing tip at the end of an optical fiber.  
         [0023]    [0023]FIG. 10 is a cross-section view of an embodiment of a diffuser, which may be used in a method according to the present invention, incorporating a scatterer adjacent the penetrating tip.  
         [0024]    [0024]FIG. 11 is a cross-section view of an embodiment of a diffuser, which may be used in a method according to the present invention, utilizing the penetrating tip to determine the spread of the laser beam.  
         [0025]    [0025]FIG. 12 is a cross-section view of an embodiment of a diffuser, which may be used in a method according to the present invention, incorporating a lens.  
         [0026]    [0026]FIG. 13 is a schematic view showing a method of introducing a diffuser into the annulus of an intervertebral disc.  
         [0027]    [0027]FIG. 14 is a schematic representation of the spine showing a diffuser inserted a second time into an annulus of an intervertebral disc, and also representing other annuli into which a diffuse light source could be inserted.  
         [0028]    [0028]FIG. 15 is a schematic view showing a method of introducing a piercing needle with a blunt-ended cannula into the annulus of an intervertebral disc. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]    [0029]FIG. 1 shows a laser treatment system  10  useful for heating of an annulus of an intervertebral disc by means of diffused light from an optical fiber  20 . Laser treatment system  10  comprises laser  11  and optical fiber  20 . A photodiode array is provided in laser  11  to produce a laser beam having a predetermined power and a predetermined wavelength useful for heating the intervertebral disc. For example, the predetermined power can be in a range of approximately 2-20 watts and the predetermined wavelength can be in a range of approximately 800-850 nanometers. As further seen in FIG. 1, an output port  16  is located within a front portion of housing  18  of laser  11 . Output port  16  enables a laser beam to be optically linked with a first end  22  of optical fiber  20  via a connector  24  so that the laser beam can be transmitted to a second end  21  of optical fiber  20 . Second end  21  of optical fiber  20  comprises an diffuser  26  emitting diffused laser light. A suitable laser  11  and corresponding optical fiber  20  is available from Ethicon-Endosurgery, Inc., in Cincinnati, Ohio, sold as the 830e LaserOptic™ Treatment system with optical fiber part number LF001. Another suitable laser  11 , the Indigo® Optima laser, will be sold by Ethicon-Endosurgery, Inc., in Cincinnati, Ohio and is anticipated to be available in 2001. A suitable fiber for use with the Indigo® Optima laser will have a part number of LF002 and also expected to be available from Ethicon-Endosurgery, Inc., in Cincinnati, Ohio in 2001.  
         [0030]    [0030]FIG. 2 depicts laser  11  with housing  18  removed to expose a controller board  28 . It will be appreciated that, among other components, controller board  28  includes a main processor  30  that receives and processes electronic signals to control the operation of laser  11  and the intensity of the light radiated by diffuser  28 . Diffuser  28  includes an optical temperature measurement device which may be, for example, a slug of silicone containing fluorescent material positioned at a distal end of fiber  20 . The fluorescent material may be, for example, alexandrite. Signals from the optical temperature measurement device are detected by laser  11  and converted to electronic signals indicative of the measured temperature. Optical signals generated by the fluorescent material, when stimulated by light of an appropriate wavelength generated by laser  11 , have a decay rate that is a function of temperature of the fluorescent material. The fluorescent material, embodied in a slug abutting the diffuser, has a temperature substantially equal to the temperature of the tissue adjacent the diffuser. If the laser stimulates the fluorescent material with light of an appropriate wavelength and an intensity that varies as a periodic function with respect to time, the fluorescent material will fluoresce with a light having a periodic function differing in phase from the phase of the stimulating signal. The light from the fluorescent material is then transmitted back to laser  11  by optical fiber  20 . In laser  11  depicted in FIG. 2, a digital signal processor  32  is provided on controller board  28  to calculate the phase difference between the stimulating signal and the fluorescent light signal. The phase difference is a function of the temperature of the fluorescent material, and the phase difference can be used to measure the temperature of tissue adjacent the diffuser. Main processor  30  and digital signal processor  32  work in concert to assure that the necessary power is provided to laser  11  to maintain tissue near diffuser  26  at a desired temperature.  
         [0031]    Laser  11  also includes an optical bench  34 . Optical bench  34  directs the treatment laser beam, a marker laser beam, and the incoming fluorescence indicative of temperature. Optical bench  34  directs a laser beam through output port  16  and into optical communication with optical fiber  20  to provide heat to tissue. Optical bench  34 , in addition to directing the laser beam which provides heat to tissue, directs a marker laser beam that illuminates the fluorescing material within optical fiber  20  to cause the fluorescing material to emit the temperature dependent returning light signal. Optical bench  34  also receives the light signals from the fluorescing materials within optical fiber  20  and utilizes light-sensing diodes to relay corresponding electrical signals to controller board  28  so that controller board  28  can use electrical components and software to calculate temperature.  
         [0032]    [0032]FIG. 3 depicts a cross-section of a typical optical fiber  20  or light source that can be used for heating intervertebral discs. Optical fiber  20  includes diffuser  26  and a proximal light-transmitting portion  34 . In light-transmitting portion  34  of optical fiber  20 , cladding  36  and proximal portion  38  of outer sleeve  40  radially surround proximal portion  39  of core  31 . Optical fiber  20  may also have a buffer layer  42  arranged to extend circumferentially between cladding  36  and proximal portion  38  of outer sleeve  40 . The material used to form cladding  36  has an index of refraction lower than the index of refraction of the material used to create core  31  to contain light within core  31 . Core  31 , in addition to its proximal portion  39 , extends through a distal portion  44  to distal face  52 . Distal portion  44  of core  31  is surrounded by optical coupling layer  46  and distal portion  48  of outer sleeve  40 . Outer sleeve  40  can consist of perfluoroalkoxy impregnated with barium sulfate.  
         [0033]    A material having an index of refraction higher than the index of refraction of core  31  forms optical coupling layer  46 , wherein UV50 Adhesive, available from Chemence, Incorporated, in Alpharetta, Ga., can be used to produce optical coupling layer  46 .  
         [0034]    A temperature measuring component  54  is filled with a temperature sensitive material and is fixed to distal face  52  of core  31 . The temperature sensitive material can be, for example, alexandrite. Alexandrite fluoresces in a temperature dependent manner upon being stimulated by light, and this property is adapted to be used to measure temperature in tissue in proximity to diffuser  26 . The same material can also reflect light back into the core to provide a more even or uniform light distribution. The same adhesive that is employed for optical coupling layer  46  can suspend the alexandrite particles to serve as the base material for temperature measuring component  54 . Other chromium-doped garnets (e.g., yttrium, alexandrite, ruby and emerald), semiconductor doped glasses, phosphors, or other temperature dependent luminescent materials can be employed to measure temperature as these materials can also fluoresce in a temperature dependent manner.  
         [0035]    As illustrated in FIG. 3, outer sleeve  40  is shaped to extend distally past temperature measuring component  54  and forms a pointed penetrating tip  50 . A tip at the distal end of optical fiber  20  may take many forms if penetration is not needed, for example, rounded or blunt, as is suitable for the application. For example, a blunt tip may be used where diffuser  26  is introduced through a needle.  
         [0036]    [0036]FIG. 4 depicts a section view of diffuser  26  showing abrasions  56  on the inner surface of distal portion  48  of outer sleeve  40 . Abrasion of inner portion of outer sleeve  40  around the circumference and along the entire length of diffuser  26  results in substantially uniform light intensity distribution in a substantially cylindrical pattern. Abrasions can be applied by, for example, rubbing the inner surface of distal portion  48  of outer sleeve  40  with a brush or rough tool. It will be understood that other means of surface roughness can substitute for abrasion and can be created by other methods, such as, for example, molding a rough profile into the inner surface of outer sleeve  40 .  
         [0037]    [0037]FIG. 5 depicts another embodiment of optical fiber  20  having a diffuser  26 . The embodiment of diffuser  26  shown in FIG. 5 also comprises core  31  surrounded by optical coupling layer  46 . Outer sleeve  40 , further comprising abrasions  56  on its inner surface, is situated radially outwardly of optical coupling layer  46 . Temperature measuring component  54  can be placed at distal end  52  of core  31 . In the embodiment depicted in FIG. 5, there is no interruption, discontinuity, or weld joint on outer sleeve  40 , so proximal portion  38  of outer sleeve  40  and distal portion  48  of outer sleeve  40  are two segments of one continuous unitarily constructed outer sleeve  40 . Outer sleeve  40 , as depicted in FIG. 5, has no weld joints or discontinuities in the outer diameter extending from the distal end of optical fiber  20  to connector  24  which conceivably tend to weaken optical fiber  20 , or which may detrimentally catch or drag optical fiber  20  to displace it while in use. When using optical fiber  20 , it may need to be bent to successfully locate the fiber in the body of a patient. Optical fiber  20  and the associated outer sleeve  40  are designed to withstand more bending than optical fibers with outer sleeves which have weld lines or discontinuities formed in the outer diameter proximal to penetrating tip  50 . As in optical fiber  20  illustrated in FIG. 3, the tip at the end may take many forms, including a blunt tip.  
         [0038]    U.S. patent application Ser. No. 09/785,571, filed Feb. 16, 2001, and hearby incorporated herein by reference, describes an embodiment of optical fiber  20  utilizing a continuous, unitary outer sleeve.  
         [0039]    Referencing FIG. 5, when light is sent through optical fiber  20 , light travels through core  31  to diffuser  26 . In diffuser  26 , light energy emerges from core  31  to optical coupling layer  46  because of the higher index of refraction of optical coupling layer  46 . Distal portion  48  of outer sleeve  40  surrounds optical coupling layer  46  and collects the light from optical layer  46 . To collect the light from optical layer  46 , distal portion  48  of outer sleeve  40  employs abrasions  56  formed on the inner surface of distal portion  48  of outer sleeve  40 . Outer sleeve  40  can use barium sulfate particles scattered within outer sleeve  40  to direct light energy evenly outwards towards the tissue. Diffuse light then emerges in all radial directions from outer sleeve  40  in the area of diffuser  26 . Light energy reaching temperature measuring component  54  is reflected back towards core  31  by particles in temperature measuring component  54 . Fluorescent properties of alexandrite particles, when stimulated by light energy of the proper wavelength, can determine the temperature of surrounding tissues by in a wavelength of light to be returned to laser  11 . The fluorescence occurs with a temperature dependent time delay that laser  11  can sense using computer circuitry.  
         [0040]    [0040]FIG. 6 depicts a block diagram of a of the operation of laser treatment system  10  utilizing optical fiber  20  incorporating the embodiment of diffuser  26  in FIG. 5. Laser source  220  working together with computer control system  236  for a laser  11  is useful for an embodiment of the inventive method. Laser source  220  and computer control system  236  may be housed together inside laser  11 . Control system  236  may comprise any computer system for monitoring response from temperature measuring component  54 , including main processor  30  and digital signal processor  32  arrayed on controller board  28 . Control system  236  may control the light intensity of diffuser  26  using the monitored temperature. Optical coupler  224  can be, for example, output port  16 .  
         [0041]    [0041]FIGS. 7 and 8 schematically show these other forms of diffusers used with laser treatment systems. A solid, generally cylindrical shaft  212  can be placed on the end of optical fiber  20 . The optical fiber  20  is embedded in the material of the shaft axially central to the shaft. A cylindrical diffusing tip  218  is placed on the energy transmitting end of optical fiber  20 . As illustrated in FIG. 7 by arrows  227 , energy radiates outwardly from diffusing tip  218  and is transmitted through the shaft including a portion of the shaft located behind penetrating tip  50 . Thus, diffusing tip  218 , together with the portion of shaft  212  surrounding diffusing tip  218  become effectively a diffuser  26 . Shaft  212  is constructed of optical quality plastic, such as polycarbonate, polysulfone, or polymethylmethacrylate (PMMA), so that laser energy may be transmitted through the entire diameter of the shaft.  
         [0042]    In one embodiment of optical fiber  20  utilizing shaft  212 , the outside diameter defined by shaft  212  may be as large as 3 mm. However, the size of the outside diameter will be determined by the desired usage. For example, when used for interstitial laser induced hyperthermia to treat BPH, a diameter range of about 0.8 to about 1.6 millimeters is appropriate. When used intraluminally in the urethra or the intervertebral disc, a diameter range of about 1 to about 4 millimeters is appropriate.  
         [0043]    In the embodiment of FIG. 7, optical fiber  20  is connected to a laser source  220  through an optical coupler  224  so as to transmit light energy from the source to distal end  226  of the fiber that is connected to diffusing tip  218 . Optical coupler  224  may take the form of output port  16  seen in FIG. 1. Laser source  220  may be within laser  11  shown in FIG. 1. In the embodiment of FIG. 7, optical fiber  20  is completely embedded in the material of shaft  212 . The portion of shaft  212  containing the distal length of optical fiber  20  to penetrating tip  50  is referred to as the penetrating portion  228 , i.e., a portion that is intended to penetrate into the tissue to be subject to treatment. As illustrated in FIG. 7, penetrating tip  50  of shaft  212  may be tapered or conically shaped.  
         [0044]    Temperature measuring component  54  may be placed at distal end of optical fiber  20  similarly to the embodiment shown in FIG. 5. Temperature measuring component  54  may contain alexandrite or other fluorescing material to return light to measure temperature to computer control system  236 . Computer control system  236  may be any computer system for monitoring response from temperature measuring component  54 , including main processor  30  and digital signal processor  32  arrayed on controller board  28  and working to assure controlled light intensity from optical fiber  20 . Computer control system  236  may reside within one physical housing  18  with laser source  220  to form laser  11 .  
         [0045]    Construction of the shaft  212  with its embedded optical fiber  20  and diffusing tip  218  can be by any convenient means. For example, optical fiber  20  with its diffusing tip  218  can be used as an insert in an injection mold and shaft  212  can be molded around the optical fiber so that otherwise exposed surfaces along the length of the optical fiber are in close contact with the shaft material. Alternatively, optical fiber  20 , its diffusing tip  218 , and the encapsulating shaft material can be co-extruded.  
         [0046]    In tissues having moderate scattering, such as the core of the intervertebral disc, diffusing tip  218  must deliver energy to the outside surface of shaft  212  with both an acceptable energy density and a correct angle of incidence. Such diffusing tips are usually formed of quartz and are commercially available, such as the spherical and cylindrical diffusers from PDT Systems. The incorporation of a diffusing tip  218  onto the distal end of optical fiber  20 , embedded within the interior of shaft  212 , results in an increase of the diffusion of the laser energy prior to its contact with the tissue. The increased area of the surface utilized for diffusing light, (for example as compared to penetrating tip  50  if the end of optical fiber  20  were placed there) greatly lowers the irradiance of the power density at the tissue interface. This alleviates a problem of overheating at the tissue/shaft interface present when a bare tip is used, while irradiating the same volume of tissue.  
         [0047]    Referring to FIG. 8, an optical fiber incorporating a diffuser  26  is shown in which optical temperature feedback and thermometry is accomplished through the use of a fiberoptic probe  240 . A solid shaft  212  again embeds the distal length of an optical fiber  20 , in this embodiment having a spherical dispersing tip  287 . Optical fiber  20  can be connected to laser source  220  and computer control system  236 . In the embodiment of FIG. 8, fiberoptic probe  240  is embedded side by side with temperature monitoring system optical fiber  250 . Prior to distal end  226  of optical fiber  20 , fiber optic probe  240  diverges upwardly to terminate at surface  242  of shaft  212 . There, semiconductor sensor  244  is disposed to sense the temperature of the tissue. Such a sensor  244  can be fabricated of a suitable semiconductor material such as gallium arsenide in prismatic form having reflective faces  246  and  248 . Semiconductor sensor  244  is optically coupled at the hypotenuse of the prism to the ends of fiber optic probe  240  and temperature monitoring system optical fiber  250 . An optical source  254 , emitting light for the temperature monitoring system, is connected to temperature monitoring optical fiber  250  while a receiver display  256  is connected to fiber optic probe  240 . Monochromatic light emitted by optical source  254  strikes on of faces  248  of the prismatic configuration of the semiconductor or sensor  244  and is reflected to the other face  246  where it is reflected a second time as a transmitted ray along fiberoptic probe  240  connected to receiver display  256 . As it transverses semiconductor sensor  244 , the radiant energy is absorbed as a function of the temperature of sensor  244 . Accordingly, the intensity of the transmitted light ray will be diminished as the temperature of semiconductor sensor  244  is increased. The intensity of the transmitted ray is readable as a temperature on receiver display  256 . See Christenson U.S. Pat. No. 4,136,566 for a description of such semiconductor sensors.  
         [0048]    It will be understood that optical temperature measurement as described in FIG. 8 could be communicated to a computer to control the light intensity of diffuser  26 . Optical source  254  and receiver display  256  can reside with computer control system  236  and laser source  220  within an alternate embodiment of laser  211 . Optical coupler  224  can couple optical fiber  20 , fiber optic probe  240 , and temperature monitoring optical fiber  250  to the alternate embodiment of laser  211 .  
         [0049]    Laser source  220  can emit light to optical fiber  20 . Spherical dispersing tip  287 , at the end of optical fiber  20  in the embodiment of FIG. 8, scatters light emitted from optical fiber  20 , thus forming an embodiment of diffuser  26 . The scattered light warms adjacent tissue. Optical source  254  emits light in the wavelength utilized for temperature monitoring and control. Returned light can be monitored through receiver display  256  attached to fiberoptic probe  240 . Electrical signals within receiver display  256 , representative of monitored light, can be forwarded to computer control system  236  for processing to control light intensity based on a temperature calculated by computer control system  236  from returned light.  
         [0050]    A wide variety of scatters and dispersers can be accommodated by the solid shaft configuration. FIGS. 9 through 12 illustrate various structures without reference to thermometry.  
         [0051]    More specifically, referring to FIG. 9, an optical fiber  20  with a diffuser  26  is shown in which the distal end of optical fiber  20  and its spherical dispersing tip  287  is disposed adjacent to penetrating tip  50  of shaft  212 . However, in this case, the assembly of optical fiber  20  and dispersing tip  287  is totally embedded in the material of the shaft  212 . In FIG. 9, spherical dispersing tip  287  disperses light through a portion of shaft  212 .  
         [0052]    In FIG. 10, rather than having a dispersing tip on the distal end  226  of optical fiber  20 , a scatterer  290  is embedded adjacent penetrating tip  50  of shaft  212  which is constituted by the shaft material. Scatterer  290  may take any of many forms, such as a spherical ball, as shown, formed by plastic and loaded with refractive scattering power such as alumina, or may take other forms suitable for diffusing energy. The exact location of scatterer  290  is not critical. It acts to diffuse the energy transmitted from the energy transmitting end  226  of optical fiber  20  and to prevent the overheating of penetrating tip  50 . The particular scatterer in the form shown in FIG. 10 can be obtained by mixing 30% of alumina in epoxy and forming the material into balls of suitable size, e.g., about 1.5 millimeters in diameter. Scatterer  290  scatters light rays through shaft  212  in the vicinity of scatterer  290  to cause the shaft  212  in the vicinity of scatterer  212  to become diffuser  26 .  
         [0053]    In the manufacture of devices such as illustrated in FIG. 10, one can injection mold the shaft  212  around optical fiber  20 , terminating at a dividing line, indicated generally at  302  in FIG. 10. In each case, a second piece of shaft is manufactured that mates with the first piece having an interior shape to accommodate scatterer  290 . PMMA is amorphous, in the nature of glass, having a glass transition temperature allowing it to be worked in the manner of glass so that upon heating and annealing, a uniform integral body is obtained.  
         [0054]    [0054]FIG. 11 illustrates the incorporation of a flat ended optical fiber  20  which is spaced a distance between distal transmitting end  334  of optical fiber  20  and penetrating tip  50  to determine the spread of the laser beam. By placing the energy transmitting end  334  of optical fiber  20  set back from penetrating tip  50 , the angular spread of the energy transmitted is increased. Refractive scattering material  336 , such as diamond powder, is disposed with the surface of penetrating tip  50  and serves to diffuse the energy transmitted from optical fiber  20 . Scattering material  336  may be placed in a separately molded conical component, joined to the main shaft as discussed with respect to FIG. 9, or may be coated on the outer surface of penetrating tip  50 .  
         [0055]    Referring to FIG. 12, the incorporation of a lens  338  positioned at the energy transmitting end of optical fiber  20  is illustrated. Divergence of energy transmitted from optical fiber  20  may be induced by bringing the energy to a focus with lens  338 . In the embodiment illustrated, a spherical lens  338  is mounted on the end of the optical fiber  20 , for example, with appropriate clear adhesive and the entire assembly is injection molded with material constituting shaft  212 . The lens  338  may be a spherical lens, a high-refractive indexed negative lens, e.g., of sapphire, or any other suitable lens capable of diverging the energy of the laser light. Lens  338  diffuses light towards the outer surface of shaft  212 .  
         [0056]    Referring now to FIG. 13, a method for heating the annulus of an intervertebral disc while avoiding inserting the device into the nucleus is shown schematically. Optical fiber  20  may be about 65 centimeters long and about one to two millimeters in diameter. Optical fiber  20  can incorporate thermometry using a temperature measurement device containing a light reactive material, such as, for example, alexandrite, to fluoresce in a temperature dependent manner.  
         [0057]    A channel  88  is formed in annulus  122  by inserting sharp-ended tubular needle  127 , as shown in FIG. 13. A light source that emits diffuse light, such as optical fiber  20  comprising diffuser  26 , is connected to laser  11  (shown schematically) to create a laser treatment system  10 . Optical fiber  20  of laser treatment system  10  is inserted into annulus  122  of intervertebral disc near damage zone  139  to a position where diffuser  26  is within an inner wall  123  and an outer wall  125  of annulus  122  inside channel  88 . Optical fiber  20  may be placed by pushing optical fiber  20  through the bore of sharp-ended tubular needle  127 . Optical fiber  20  may be placed utilizing, for example, ultrasonic guidance or magnetic resonance imaging guidance to obtain an image of optical fiber  20  and surrounding tissue. Laser  11  delivers diffuse light energy through optical fiber  20  to heat the portion of annulus  122  in contact or near diffuser  26 . Application of a phototheramic dosage will produce the desired temperature in the damaged zone  139  of annulus  122  without damaging spinal cord  129  or nucleus  130 . The damaged zone  139  may be heated to a temperature level to cause a change in physical characteristics of annulus  122  within damaged zone  139 . The damaged zone  139  may be, for example, heated to a temperature to cause damage to pain-causing nerve endings that have grown into annulus  122  in the region of damaged zone  139 . The damaged zone  139  may also be, for example, heated to a temperature to cause collagen of annulus  122  within damaged zone  139  to shrink without ablating or vaporizing nucleus  130 . It has been found that ingrown annulus nerve endings become damaged at a temperature at about 45° C., while collagen shrinks at about a temperature of 60° C. Nucleus  130  would vaporize at a temperature of approximately 80° C. to a temperature of approximately 100° C.  
         [0058]    The patient can realize advantages of inserting diffuser  26  into annulus  122  to directly heat annulus  122  without inserting devices through nucleus  130 . By utilizing the method of heating annulus  122  with diffuser  26  inside annulus  122 , heating can be confined to the region of damaged zone  139  of annulus  122 . Furthermore, the method of inserting diffuser  26  directly into annulus  122  creates channel  88  within damaged zone  139 , eliminating the necessity of creating a channel  88  in a healthy portion of annulus  122 . By transferring heat directly to annulus  122  with diffuser  26  inside the annulus, the annulus can be heated to a temperature higher than nucleus  118 . Heating annulus  122  directly allows annulus  122  to be raised to a therapeutic temperature without the necessity of raising the nucleus temperature to a value higher than the therapeutic temperature needed in annulus  122 . As a further treatment, a physician can continue to cause diffuser  26  to emit light as optical fiber  20  is withdrawn from channel  88 . Continuing to emit diffuse light from diffuser  26  can raise the temperature of annulus  122  near channel  88  to heat channel  88  to cause shrinkage of collagen of annulus  122  in the vicinity of channel  88  as optical fiber  20  is withdrawn.  
         [0059]    Optical temperature measurements of the tissue in the vicinity optical fiber  20  can be made. When diffuser  26  touches annulus  122 , optical temperature measurements of annulus  122  can be made by, for example, utilizing computer controlled methods and temperature dependant fluorescing materials described herein. Optical temperature measurements can then be communicated to laser  11 . Computer control can then be used to vary the output light intensity from optical fiber  20  based on the temperature measurements of annulus  122 .  
         [0060]    [0060]FIG. 14 demonstrates schematically that diffusers  26  can be placed, as desired, into other annuli  122  through channels  88  in spine  154  and light energy can be applied interstitially as taught above. A diffuser  26  on optical fiber  20  is placed into a second intervertebral disc  118  and aligned within annulus  122  of the second intervertebral disc  118 . Diffuse light is then used to heat annulus  122  of the second intervertebral disc  118  in the same manner as taught above. The diffuse light will radiantly heat the annulus  122  of the second intervertebral disc  118  to the desired temperature to destroy nerve endings or to cause shrinkage of the collagen contained within the annulus  122  of the second intervertebral disc  118 .  
         [0061]    Optical fibers  20  may also be placed, if desired, into another portion of the same annulus  122  to heat the other portion of annulus  122 . Diffuser  26  of optical fiber  20  is placed into a second portion of annulus  122  and diffuse light is applied in a controlled manner in the method taught above. The diffuse light will radiantly heat the second portion of annulus  122  to the desired temperature to destroy nerve endings or to cause shrinkage of the collagen contained within the second portion of the annulus  122  of the same intervertebral disc  118 .  
         [0062]    As with the first application of heat to annulus  122 , computer control can be employed to control and to monitor annulus temperature when applying heat to either the same annulus  122  for a second time or to another annulus  122  for the first time.  
         [0063]    It will be recognized that equivalent structures may be substituted for the structures illustrated and described herein and that the described embodiment of the invention is not the only structure which may be employed to implement the claimed invention. For example, FIG. 15 shows blunt-ended cannula  156  containing a piercing needle in the bore and extending from the distal end could substitute for sharp-ended tubular needle  127 . A physician can alternatively insert piercing needle  158  through the inner diameter of blunt-ended cannula  156  and use the assembly to pierce annulus  122 . After piercing channel  88  into annulus  122 , a physician can remove the piercing needle  158  and have available an open blunt-ended cannula for insertion of optical fiber  20 . Optical fiber  20 , or any light source, may be inserted through blunt-ended cannula  156 . The physician can then supply power to the light source to emit diffuse light to heat annulus  122  of intervertebral disc  118  to a therapeutic temperature as described above. The physician can also use piercing needle  158  and blunt-ended cannula  156  in the same manner described above to pierce the same annulus  122  a second time to heat another portion of annulus  122 , or to pierce a second annulus  122  of a second intervertebral disc  118 .  
         [0064]    While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.