Patent Publication Number: US-2018028130-A1

Title: Visualization systems, instruments and methods of using the same in spinal decompression procedures

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. patent application Ser. No. 13/844,324 filed on Mar. 15, 2013, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to medical systems and, more particularly, to visualization systems, spinal decompression instruments, treatment systems, and methods for treating the spine. 
     BACKGROUND 
     Spinal nerve compression can be caused by narrowing of the spinal canal associated with arthritis (e.g., osteoarthritis) of the spine, degeneration of spinal discs, and thickening of ligaments. Arthritis of the spine often leads to the formation of bone spurs which can narrow the spinal canal and press on the spinal cord. In spinal disk degeneration, inner tissue of the disk can protrude through a weakened fibrous outer covering of the disk. The bulging inner tissue can press on the spinal cord and/or spinal nerve roots. Ligaments located along the spine can thicken over time and press on the spinal cord and/or or nerve roots. Spinal nerve compression can cause lower back pain, hip pain, and leg pain and may also result in numbness, depending on the location of the compressed nerve tissue. In the lower back, spinal stenosis may lead to spinal cord compression and numbness of the legs. Unfortunately, it may be difficult to treat spinal nerve compression without injuring or traumatizing non-targeted tissue. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The same reference numerals refer to like parts or acts throughout the various views, unless otherwise specified. 
         FIG. 1  is a side view of a visualization system in accordance with an embodiment of the disclosure. 
         FIG. 2  is a side view of a visualization instrument protecting a spinal cord in accordance with an embodiment of the disclosure. 
         FIG. 3  is an enlarged superior view of tissue adjacent to a vertebral foramen and the visualization instrument positioned between a ligamentum flavum and dura sac. 
         FIG. 4  is a flowchart illustrating a method for reducing spinal nerve compression in accordance with one embodiment of the disclosure. 
         FIGS. 5-8  illustrate various stages of a procedure for reducing spinal nerve compression in accordance with one embodiment of the disclosure. 
         FIG. 9  is a superior anatomical view of a visualization instrument positioned using a transforamonal approach in accordance with an embodiment of the disclosure. 
         FIG. 10  is an enlarged view of the visualization instrument of  FIG. 9  adjacent to the spinal cord in accordance with one embodiment of the disclosure. 
         FIG. 11  is a superior anatomical view of a visualization instrument positioned using a lateral approach in accordance with an embodiment of the disclosure. 
         FIG. 12  is an enlarged view of the vertebral foramen of  FIG. 11  with the visualization instrument positioned between the spinal cord and the ligamentum flavum. 
         FIG. 13  is a side view of a distal portion of a visualization instrument positioned within a dura sac in accordance with an embodiment of the disclosure. 
         FIG. 14  is a superior anatomical view of the vertebral foramen of  FIG. 13  in accordance with an embodiment of the disclosure. 
         FIG. 15  is a side view of a visualization system and a treatment system positioned at different levels along a spine in accordance with an embodiment of the disclosure. 
         FIG. 16  is a side view of the visualization system and the treatment system of  FIG. 15  with the spine shown in cross-section. 
         FIGS. 17-19  are side views of a visualization instrument and treatment system positioned along a spine. 
         FIG. 20  is a side view of the visualization instrument in accordance with an embodiment of the disclosure. 
         FIG. 21  is a plan view of the visualization instrument of  FIG. 20 . 
         FIG. 22  is a side view of a distal portion of the visualization instrument of  FIG. 20  positioned between the ligamentum flavum and the spinal cord in accordance with an embodiment of the disclosure. 
         FIG. 23  is an isometric view of a visualization instrument in accordance with an embodiment of the disclosure. 
         FIG. 24  is a plan view of a visualization instrument capable of delivering contrast media in accordance with an embodiment of the disclosure. 
         FIG. 25  is a plan view of a visualization instrument with the deployable media delivery element in accordance with an embodiment of the disclosure. 
         FIG. 26  is a plan view of the delivery element of  FIG. 25  in a deployed position. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure describes various embodiments in medical systems, instruments, devices, and associated methods of use. At least some embodiments include a visualization instrument that can be viewed to assist in a spinal procedure. Visualization techniques can be used to view at least a portion of a treatment instrument (e.g., a distal tip of a tissue removal instrument) and at least a portion of the visualization instrument to perform the procedure. Certain details are set forth in the following description and in  FIGS. 1-26  to provide a thorough understanding of such embodiments of the disclosure. Other details describing well-known structures and systems often associated with, for example, visualization, treating the spine, spinal nerves (e.g., nerves in the spinal cord, nerves in nerve roots exiting the spinal cord, etc.), or decompression procedures are not set forth in the following description to avoid unnecessarily obscuring the description of various embodiments of the disclosure. 
     The terms “distal” and “proximal” within this description, unless otherwise specified, reference a relative position of the portions of a system, instruments, and/or associated delivery devices with reference to an operator and/or a location in the patient. For example, in referring to visualization instruments described herein, the term “proximal” can refer to a position closer to the operator, and the term “distal” can refer to a position that is more distant from the operator. 
     A. Overview 
     At least some visualization instruments disclosed herein can be used to identify features, such as targeted tissue and non-targeted tissue, and/or used as a point of reference to position other instruments and tools. In some embodiments, a visualization instrument can be positioned to protect the spinal cord and define a working space. A series of treatment instruments can be moved within the working space to crush, separate, cut, debulk, break, fracture, remove, or otherwise alter tissue at a treatment site. If the treatment instruments move towards the spinal cord, the visualization instrument can serve as a working barrier to inhibit or prevent injury and/or trauma to the spinal cord. 
     At least some embodiments are methods for treating a subject (e.g., a human subject). The methods include positioning a tissue protector of a visualization instrument in an epidural space. The tissue protector can be viewed via fluoroscopy to identify margins of the epidural space, dura, ligamentum flavum, nerve roots, and/or other tissue. The wide range of different types of fluoroscopy (e.g., anterior posterior imaging, lateral imaging, contralateral oblique imaging, etc.) can be used to view the visualization instrument, as well as treatment tools or delivery devices used to perform a procedure. 
     At least some embodiments are methods for performing a procedure on a subject and include positioning a distal portion of a visualization instrument in a vertebral column of the subject. Another instrument (e.g., a treatment instrument) can be positioned while viewing both the treatment instrument and a distal portion of the visualization instrument under, for example, fluoroscopy. A spinal decompression procedure can be performed using the treatment instrument. In one embodiment, the visualization instrument can be a radiopaque epidural catheter having a flexible elongated main body. In some procedures, the epidural catheter can be moved along the vertebral column through any number of vertebrae. In other embodiments, the visualization instrument is a catheter configured to be positioned within the dura sac or other suitable location. Such catheters can have a relatively low profile. An opening, if any, defined by, and laterally adjacent to, the distal portion can be smaller than a distal head or tool portion of the treatment instrument. As such, the distal head of the treatment instrument is prevented from contacting non-target tissue. In some embodiments, the visualization instrument includes an elongate radiopaque wire. The wire can extend from a distal end of the visualization instrument to a proximal end of the visualization instrument. 
     In some embodiments, a method for positioning an instrument in a subject comprises moving the tissue protector of the visualization instrument through a subject. The tissue protector can be moved from a delivery configuration to a deployed configuration to define a working space. A decompression procedure can be performed at the treatment site while viewing the deployed tissue protector. When using a treatment instrument at the working space, the treatment instrument and non-targeted tissue can be kept on opposite sides of the tissue protector. 
     In yet other embodiments, a method for performing a procedure on a subject includes positioning a tissue protector of a visualization instrument in an epidural space of a subject. A treatment instrument can be moved between a first vertebra and a second vertebra while the tissue protector remains in the epidural space and viewed via fluoroscopy. A physician can view both the treatment instrument and the tissue protector before, during, and after performing a procedure using the treatment instrument. 
     In some embodiments, a treatment system for treating spinal compression comprises a visualization instrument including a tissue protector configured to be positioned in an epidural space and viewed using a fluoroscopy. The treatment system can further include a treatment instrument configured to perform a decompression procedure at a treatment site while the tissue protector prevents access to the spinal cord. In some embodiments, the tissue protector can cover a posterior region of the spinal cord facing a treatment site. 
     B. Visualization Systems, Visualization Procedures, and Decompression Procedures 
       FIG. 1  is a side view of a visualization system  100  in accordance with one embodiment of the disclosure. The visualization system  100  includes a visualization instrument  110  and a delivery device in the form of a cannula  120 . The cannula  120  extends through a subject&#39;s skin  140 , subcutaneous tissue  142 , and a supraspinal ligament  150 . The visualization instrument  110  extends through the cannula  120  and along a spinal or vertebral column  123 . 
       FIG. 2  is a detailed side view of a portion of the visualization system  100 . Vertebra  170 ,  174  are shown in cross section.  FIG. 3  is a detailed superior anatomical view of a spinal canal  200 . Referring to  FIGS. 2 and 3  together, the visualization instrument  110  includes a distal portion  163  positioned between a ligamentum flavum  194  and a spinal cord  180 . The spinal cord  180  is positioned between the ligamentum flavum  194  and a ligament  198  and extends from the brain to the bottom of the spine. Spinal nerves branch from the spinal cord  180 , exit the spine, and extend to the parts of the body. 
     The distal portion  163  is viewable using, for example, fluoroscope, MR imaging, CT imaging, or other suitable imaging techniques. By viewing the distal portion  163 , a physician can conveniently identify the location and/or margins of the spinal cord  180  and ligamentum flavum  194 . The distal portion  163  can be moved to different positions to identify targeted or non-targeted tissue, which can include, without limitation, the ligamentum flavum  194 , the spinal cord  180 , the ligament  198 , nerves branching from the spinal cord  180 , vertebrae  170 ,  174 , and other features or anatomical structures proximate to the spine. The distal portion  163  can include a tissue protector  190  (e.g., a section of the distal portion  163 ) configured to inhibit, limit, or substantially prevent damage and/or injury to the spinal cord  180  and can define a working space  127  ( FIG. 2 ). 
       FIG. 4  is a flow chart illustrating a method  301  for visualizing and performing spinal nerve decompression in accordance with an embodiment of the disclosure. At stage  300 , a delivery device can provide access to a treatment site. At stage  302 , a visualization instrument can be positioned using fluoroscopy. At stage  304 , one or more treatment instruments can be delivered to a working space defined, at least in part, by a tissue protector of the visualization instrument. At stage  305 , a spinal procedure can be performed. The spinal procedure (including posterior lumbar decompression procedures) can involve altering tissue, implanting devices, or other procedures for treating various spine conditions. Tissue can be altered by cutting tissue, loosening tissue, crushing bone, or otherwise disrupting tissue at a treatment site. In some decompression procedures, tissue can be removed from one or more lateral recesses of a vertebra. In other decompression procedures, tissue can be removed from the spinal cord, vertebrae, or other site along the spine, as discussed in connection with  FIGS. 8-19 and 22 . 
       FIGS. 5-8  illustrate various stages of a procedure in accordance with one embodiment of the disclosure. Referring now to  FIG. 5 , the cannula  120  can be delivered using a posterior midline approach. An incision can be made in the supraspinal ligament  150  and the cannula  120  can be passed through the incision until it is inserted between spinous processes  240 ,  244 . A distal end  252  of the cannula  120  can be positioned within an interspinous space  261 . Delivery sheaths, delivery catheters, access ports, or other types of delivery devices can also be used to provide access to the treatment site. The distal portion  163  can be inserted into a proximal end  250  of the cannula  120 , moved along a passageway of the cannula  120 , and delivered out of the distal end  252 . The distal portion  163  can be moved in the anterior direction through the interspinous space  261 , through the ligamentum flavum, and into the epidural space (or other desired location). 
       FIG. 6  shows the visualization instrument  110  including the main body  280  and a proximal portion  269  positioned outside of the subject. The proximal portion  269  can include a steering assembly  270  used to steer the visualization instrument  110  by, for example, operating control elements  272 ,  274 . One or more pull wires, pull rods, or other components can extend through the main body  280  and can be coupled to the distal end of the visualization instrument  110 . The control elements  272 ,  274  can be levers, dials, or other elements that can be manipulated to bend, rotate, displace, or otherwise move the instrument  110 . In other embodiments, the visualization instrument  110  may not have steering capability. A delivery device can be used to guide such visualization instruments to a desired site. 
       FIGS. 7 and 8  show a treatment instrument  299  that has been delivered through the cannula  120  and positioned at the working space  127 . One or more markers (one marker  197  is shown in  FIG. 8 ) can be used to identify the spinal cord  180  and can serve as a reference point to position the treatment instrument  299 . However, markers can also be located on the exterior surface of the main body  280  and/or tissue protector  190 , within the main body  280  and/or tissue protector  190 , or at other suitable locations. Markers can include, without limitation, an array of radiopaque markers made of radiopaque materials, such as metals, radiopaque polymers, or the like. The radiopaque markers can be evenly or unevenly spaced apart along the length of the tissue protector  190 . In other embodiments, the entire main body  280  and distal portion  193  can be made of radiopaque material. For example, the main body  280  and tissue protector  190  can be a flexible metal wire (e.g., an elongate radiopaque wire) or a bundle of flexible metal wires. 
     Referring to  FIG. 8 , a longitudinal axis  191  of the tissue protector  190  is oriented in the superior-inferior direction and is generally parallel to the long axis of the spinal cord  180 . Additionally, the axis  191  can be generally perpendicular to the portion of the main body  280  extending in posterior-anterior direction. The ligamentum flavum  194  and spinal cord  180  can snugly hold the tissue protector  190  to help minimize movement of the instrument  110 , even if the instrument  299  contacts the main body  280 . An atraumatic tip  314  can be moved in the superior direction (indicate by arrow  316 ) to position most of the tissue protector  190  within the vertebral canal  200 , but it can be located at other locations. In some embodiments, the tissue protector  190  can made of a compliant material (e.g., silicon, rubber, elastomers, etc.) to cushion tissue. In other embodiments, the tissue protector  190  can be made of a rigid or semi-rigid materials to distribute pressure to a large area of tissue. 
       FIG. 8  shows the instrument  299  having a working or distal portion  307  configured to break, cut, scrape, crush, or otherwise alter target tissue at the treatment site  263 . The target tissue can include, without limitation, bone (e.g., lamina, bone of lateral recesses, facets, including inferior facets, etc.), bone spurs (e.g., bone spurs associated with osteoarthritis), tissue bulging from discs, tissue of thickened ligaments, spinal tumors, displaced tissue (e.g., tissue displaced by spinal injury), or other tissue that may cause or contribute to spinal nerve decompression. In procedures treating stenosis, the distal portion  307  can be used to remove tissue associated with central canal stenosis, lateral recess stenosis, or other types of stenosis. 
     If the distal portion  307  is moved in the anterior direction (indicated by arrow  310 ) the tissue protector  190  can physically block the distal portion  307 . The distal portion  307  can also be inserted into the vertebral canal  200  without injuring or traumatizing the spinal cord  180 . As a result, the instrument  299  can be safely moved throughout the working space  127 . The shape and configuration of the tissue protector  190  can be selected based on the configuration of the distal portion  307 . For example, the tissue protector  190  can be large enough to ensure that exposed regions, if any, of the spinal cord  180  (i.e., the regions of the spinal cord  180  accessible via the interspinous space  313 ) are smaller than the distal portion  307 . 
     The treatment instrument  299  can be, without limitation, a surgical instrument (e.g., a scalpel), scraping instrument, cutting instrument, or other instrument or tool for altering tissue. U.S. Patent Application No. 61/755,392, filed on Jan. 22, 2013, discloses various types of surgical instruments that can be used in, or incorporated into, the systems and methods disclosed herein. Such instruments include, but are not limited to, debulker instruments, tissue removal instruments, cutting instruments, and debulker instruments and other systems, instruments, and devices disclosed in U.S. Application No. 61/755,329, which is incorporated by reference in its entirety. 
     To help position the distal portion  307 , both the distal portion  307  and the tissue protector  190  can be viewed using, for example, fluoroscopy. The tissue protector  190  can serve as a reference point to help the physician identify critical areas of non-targeted tissue and/or assist in positioning of the distal portion  307 . In some procedures, the tissue protector  190  can remain substantially stationary while the distal portion  307  is used to perform a procedure at the treatment site  263 , although the tissue protector  190  can be repositioned any number of times during a treatment session. 
     After completing the procedure, the instrument  299  can be removed from the subject. The visualization instrument  110  and the cannula  120  can then be removed from the subject without injuring and/or traumatizing tissue. 
       FIGS. 9 and 10  show a visualization instrument  292  positioned using a transforaminal approach. The visualization instrument  292  can include a distal portion  294  with a tissue protector  293  extending laterally about the spinal cord  180  to provide a wide working space. An operator can grip the proximal portion  297  positioned outside of the subject to reposition the tissue protector  293 . Treatment instruments or tools can be delivered using a transforaminal approach to perform decompression procedures at, for example, the lateral recesses. The tissue protector  293  can have a generally rectangular shape, partially cylindrical shape, or other shape or configuration suitable for overlaying the spinal cord  180 . 
     Visualization instruments can be delivered using other access techniques. For example,  FIGS. 11 and 12  show a visualization instrument  303  positioned using a lateral approach and having a distal portion  311  with a tissue protector  309  overlaying the posterior region of the dura sac  181 .  FIG. 12  shows the tissue protector  309  adjacent to opposing sides  500 ,  502  of the ligamentum flavum  194 . In some embodiments, the tissue protector  309  wraps around most of the circumference of the spinal cord  180  to protect the dura sac  181  when performing decompression procedures at the lateral-most regions of the vertebral foramen  503 . An operator can use a handle  317  ( FIG. 11 ) at the proximal portion  315  ( FIG. 11 ) to manually reposition the tissue protector  309 . 
       FIGS. 13 and 14  show a visualization instrument  402  that includes a distal portion  401  with a tissue protector  403  positioned within dura sac  181 . Referring to  FIG. 13 , the tissue protector  403  spans a gap  209  between the vertebra  170 ,  174 . As such, the entire length of the spinal cord  180  positioned between the vertebra  170 ,  174  is protected. Other visualization instruments can also be positioned within the spinal cord  180 . For example, the visualization instrument  110  of  FIGS. 1 and 2  can be inserted into the dura and moved in the anterior or superior direction. To perform a myelogram, such instrument can have a port capable of delivering contrast media directly into the spinal cord  180 . 
     Referring now to  FIG. 14 , the tissue protector  403  is positioned between the dura sac  181  and spinal nerves  405 . If a treatment instrument or tool punctures the dura sac  181 , the tissue protector  403  can shield the spinal nerves  405 . Multiple visualization instruments can be used together in a single procedure. In one procedure, the visualization instrument  402  can be used to protect spinal nerves  405  while another visualization instrument, such as the visualization instrument  110  of  FIGS. 1 and 2 , protects the dura sac  181 . 
       FIG. 15  is a side view of a visualization instrument  610  and a treatment system  612  in accordance with an embodiment of the disclosure.  FIG. 16  is a detailed side view of portions of the visualization instrument  610  and treatment system  612 . The spine  121  is shown in cross-section in  FIG. 16 . The visualization instrument  610  extends through an interspinous space  613  and its main body  620  extends through the vertebral canal  629  ( FIG. 16 ). A tissue protector  690  can extend along the spinal canal  621  to a location superior to the treatment site. In  FIG. 16 , the treatment site is between the spinous processes  450 ,  451 , so the tissue protector  690  can extend from a first level  660  to an adjacent level  661 , thereby spanning a gap  340  ( FIG. 16 ). 
     Referring again to  FIG. 15 , the treatment system  612  can include a delivery device in the form of a cannula  644 , an instrument  619 , and an implantable device  710 . The implantable device  710  can be an interspinous spacer, fixation device, plate, or other type of spinal implant. One suitable such implantable device is the Superion® interspinous spacer from VertiFlex, Inc. or other similar device. The implantable device  710  can be implanted while imaging the device  710  and the tissue protector  690  and can be delivered via a midline approach, a transforaminal approach, an ipsilateral approach, or a lateral approach. The implantable device  710  can be deployed to engage, and couple to, the spinous processes  450 ,  451  to, for example, reduce or eliminate spinal compression, pain, or combinations thereof. Throughout the deployment process, the spinal cord  180  is protected by the tissue protector  190 . 
     After implanting the device  710 , the treatment system  612  can be removed from the subject. The visualization instrument  610  can be pulled proximally through the cannula  120  and removed from the subject. The visualization instrument  610  and treatment system  612  can be used to treat other locations along the spine. 
       FIG. 17  shows a visualization instrument  800  entering the spine at the lumbar region  810 . A treatment instrument  820  can perform a procedure at the thoracic region  812  while a tissue protector  833  (shown in phantom) protects non-targeted tissue at the thoracic region  812 . The visualization instrument  800  can be a catheter (e.g., a radiopaque epidural catheter or other instrument disclosed herein).  FIG. 18  shows the visualization instrument  800  accessing the spine or vertebral column at the thoracic region  812  to protect non-targeted tissue at the lumbar region  810 .  FIG. 19  shows the visualization instrument  800  positioned at the sacral region  850  to perform a procedure at another level. Because the tissue protectors disclosed herein can be conveniently moved along the spine, the tissue protectors can be inserted at an access that is separated from the treatment site by one or more vertebrae. Accordingly, the access site can be at the cervical region, thoracic region, lumbar region, or sacral region to perform a procedure at treatment site at the cervical region, thoracic region, lumbar region, or sacral region. 
       FIG. 20  is a side view of a visualization instrument  900  that includes a distal portion  901 , a proximal portion  903 , and a main body  905 . The distal portion  901  includes a tissue protector  902  in accordance with an embodiment of the disclosure.  FIG. 21  is a plan view of the tissue protector  902  that includes protective arms  912  (individually  912   a ,  912   b,    912   c,    912   d,    912   e,    912   f  in  FIG. 21 ) movable from a delivery configuration  917  (shown in phantom line in  FIG. 20 ) to the deployed configuration  919 . To deliver the tissue protector  902 , the arms  912  can be in the delivery configuration  917  for delivery through a cannula or other delivery device. As the tissue protector  902  exits the cannula, the arms  912  to move from the delivery configuration to the deployed configuration, as indicated by arrow  924 ,  926 . In some embodiments, the arms  912  are biased outwardly and can self-deploy. In other embodiments, the arms  912  can be deployed using one or more balloons, pull rods, pull wires, or other component for providing controlled movement of the arms  912 . 
     Referring to  FIG. 21 , the arms  912  can be generally evenly spaced apart from one another and made of metal, plastic, or other material capable of withstanding contact with a treatment instrument so as protect adjacent tissue. In some embodiments, a protective or shielding member  920  (shown in phantom line) can be carried by the arms  912  and can include, without limitation, a mesh, a net, a sheet (single layer or multilayer layer sheet), drapable fabric, a plate, or other protective barrier (i.e., a barrier for preventing injury or trauma to tissue) that can assume different configurations by expanding, unfurling, or the like. The protective member  920  can have a wide range of shapes and configurations, including a generally circular shape, spherical shape, rectangular shape, or the like. 
       FIG. 22  shows the tissue protector  902  in the deployed configuration. Tips  930  of the arms  912  can be positioned within vertebral canals  200 ,  204  to protect the entire length of the spinal cord  180  exposed by the interspinous space  911 . In some embodiments, the entire portion of the spinal cord  180  accessible via the interspinous space  911  is covered by the protective member  920  to prevent puncturing of the dura sac  181 , while the arms  912  can help withstand significant forces from treatment instruments. Accordingly, the arms  912  and protective member  920  can work together to provide enhanced protection. 
       FIG. 23  is an isometric view of a visualization instrument  1100  including a tissue protector  1102  in accordance with another embodiment of the disclosure. The tissue protector  1102  is movable from a delivery configuration  1110  (shown in phantom line) to the deployed configuration  1112 . The tissue protector  1102  can include an inflatable member (e.g., a single chamber balloon, a multi-chamber balloon) that can be inflated with a fluid to provide cushion to further inhibit or prevent tissue trauma and/or injury. Such inflatable members can be made of a highly compliant material, including, without limitation, silicon, rubber, elastomers, or the like. One or more markers can be positioned along the exterior surface or within the tissue protector  1102 . The inflation fluid can be visualization media (e.g., contrast media) in the form of a flowable radiopaque substance (e.g., a radio contrast agent, barium sulfate solution, or the like) or other viewable substance. Non-ionic contrast media can be used if the tissue protector  1102  is positioned within the dura sac. As a result, the inflation fluid can provide both cushioning and visualization functionality. 
       FIG. 24  is an elevational view of a visualization instrument  1200  that includes a distal portion  1201 , a proximal portion  1203 , and a main body  1205  therebetween. The distal portion  1201  includes a tissue protector  1211  having deployable elements  1204 ,  1204  movable from a delivery configuration inside the body  1205  to the illustrated deployed configuration. Visualization media can be delivered out of a port  1220  for additional imaging. To perform an epidurogram, the visualization media can be delivered out of the port  1220  when the tissue protector  1211  is positioned in the epidural space. The members  1202 ,  1204  can be deployed before, during, or after delivery of the Visualization media. Other visualization instruments disclosed herein can also include one or more ports for delivering media. 
       FIG. 25  is a side elevational view of a visualization instrument  1300  in accordance with an embodiment of the disclosure.  FIG. 26  is a side view of the visualization instrument  1300 . Referring to  FIG. 25 , the visualization instrument  1300  includes a distal portion  1301 , a proximal portion  1303 , a main body  1305 , and a media delivery element  1320  in an undeployed position. In some embodiments, the media delivery element  1320  can be housed within a lumen  1321 . Referring to  FIG. 26 , the delivery element  1320  can be moved out of an aperture  1330  to deliver media. 
     In myelography procedures, a tissue protector  1333  can moved along the epidural space adjacent to the dura. The delivery element  1302  can be moved out of the aperture  1330 , which faces the dura, to puncture the dura sac. After an end  1329  is within the dura, visualization media (e.g., a non-ionic contrast media) can be delivered directly into the spinal fluid surrounding the spinal cord. The delivery element  1320  can be positioned under fluoroscopic guidance to ensure that spinal nerves are not damaged or injured. After delivering the media, the delivery element  1302  can be drawn back into the main body  1323 . As such, the media can be kept outside of the epidural space and localized within the dura. Myelography can provide detailed images (i.e., myelograms) of the spinal cord, thecal sac, nerve tissue (including nerve roots), or other features of interest. Additionally, myelography procedures can provide enhanced viewing of non-targeted structures (e.g., dura), and nerve roots compared to epidurography procedures. For example, visualization media of a myelography procedure may travel (e.g., via controlled leakage) to nerve roots to visualize the nerve roots when removing bone of the neural foramen. In some embodiments, myelography visualization media can be used to verify decompression of the spinal cord because the dura can move outwardly to confirm that the pressure applied to the spinal cord is decreased or eliminated. If the dura is damaged (e.g., tears, leaks, or the like), myelography visualization media can escape out of the damaged region of the dura. A physician can view the leakage to confirm that the dura has been damaged, as well as identifying the location of the damage. The physician can then repair the dura or otherwise alter the surgical procedure. Accordingly, myelography visualization media can be used to provide useful real-time feedback. Other visualization instruments disclosed herein can have delivery elements similar to the delivery element  1302  discussed in connection with  FIGS. 25 and 26  in order to deliver contrast media (or other media) into tissue. For example, the tissue protector  190  of  FIG. 2  can have a deployable delivery element. 
     Although many embodiments discussed herein are discussed in the context of fluoroscopy, other visualization techniques can be used to view treatment instruments and/or visualization instruments to identify targeted features, treatment sites, and/or non-targeted features. Treatment instruments and/or visualization instruments can be viewed when altering tissue and/or delivering a spinal device, such as a spinal implant, a spacer device, prosthetics disk, or the like. In certain procedures, visualization instruments disclosed herein can be used to identify margins of the epidural space, dura, ligamentum flavum, and/or nerve roots relative to the lamina and interlaminar space, as well as the features of instruments. 
     The visualization instruments disclosed herein can be located at other locations to protect other non-target tissue. Other embodiments can include tissue protectors specifically designed to protect portions of the vertebrae, nerve roots, or other structures near the spine. Additionally, multiple visualization instruments can cooperate to simultaneously protect tissue while also serving as reference points under visualization. 
     CONCLUSION 
     The above detailed descriptions of embodiments of the technology are not intended to be exhaustive or to limit the technology to the precise form disclosed above. Although specific embodiments of, and examples for, the technology are described above for illustrative purposes, various equivalent modifications are possible within the scope of the technology, as those skilled in the relevant art will recognize. For example, while steps are presented in a given order, alternative embodiments may perform steps in a different order. The various embodiments described herein may also be combined to provide further embodiments. For example, features from various instruments can be combined with features and methods disclosed in U.S. Pat. No. 8,012,207; U.S. Pat. No. 8,123,807; U.S. Pat. No. 8,152,837, and U.S. application Ser. No. 12/217,662 (U.S. Publication No. 2008/0287997) which are incorporated by reference in their entireties. U.S. Provisional Application Nos. 61/639,828, 61/745,470, and 61/755,329, which are hereby incorporated by reference herein and made a part of this application. A wide range of treatment instruments can be used to address a wide range of symptoms, conditions, and/or diseases, including, without limitation, spinal nerve compression (e.g., spinal cord compression, spinal nerve root compression, or the like), spinal disk herniation, osteoporosis, stenosis, or other diseases or conditions. In one embodiment, the system  100  is used to perform a spinal cord decompression procedure, which can include removing bone from one or more vertebrae, separating the ligamentum flavum from one or more vertebrae, cutting or debulking the ligamentum flavum, and/or removing loose tissue. 
     Where the context permits, singular or plural terms may also include the plural or singular term, respectively. Moreover, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in reference to a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of the items in the list. Additionally, the term “comprising” is used throughout to mean including at least the recited feature(s) such that any greater number of the same feature and/or additional types of other features are not precluded. It will also be appreciated that specific embodiments have been described herein for purposes of illustration, but that various modifications may be made without deviating from the technology. Further, while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein.