Patent Publication Number: US-2023148023-A1

Title: Lateral retractor system for minimizing muscle damage in spinal surgery

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATIONS 
     The application is a continuation-in-part of pending prior U.S. Pat. Application No. 16/533,368, filed Aug. 6, 2019 by Edward Rustamzadeh for “LATERAL RETRACTOR SYSTEM FOR MINIMIZING MUSCLE DAMAGE IN SPINAL SURGERY,” which is a continuation of prior U.S. Pat. Application Serial No. 16/356,494, filed Mar. 18, 2019 by Edward Rustamzadeh for “LATERAL RETRACTOR SYSTEM FOR MINIMIZING MUSCLE DAMAGE IN SPINAL SURGERY” and issued as U.S. Pat. No. 10,426,452 on Oct. 1, 2019, which is a divisional of prior U.S. Pat. Application Serial No. 16/273,322, filed Feb. 12, 2019 by Edward Rustamzadeh for “LATERAL RETRACTOR SYSTEM FOR MINIMIZING MUSCLE DAMAGE IN SPINAL SURGERY” and issued as U.S. Pat. No. 10,363,023 on Jul. 30, 2019, all of which patent applications are incorporated herein by reference. 
    
    
     BACKGROUND 
     The spine is a flexible column formed of a plurality of bones called vertebrae. The vertebrae are hollow and piled one upon the other, forming a strong hollow column for support of the cranium and trunk. The hollow core of the spine houses and protects the nerves of the spinal cord. The different vertebrae are connected to one another by means of articular processes and intervertebral, fibrocartilaginous bodies, or spinal discs. Various spinal disorders may cause the spine to become misaligned, curved, and/or twisted or result in fractured and/or compressed vertebrae. It is often necessary to surgically correct these spinal disorders. 
     The spine includes seven cervical (neck) vertebrae, twelve thoracic (chest) vertebrae, five lumbar (lower back) vertebrae, and the fused vertebrae in the sacrum and coccyx that help to form the hip region. While the shapes of individual vertebrae differ among these regions, each is essentially a short hollow shaft containing the bundle of nerves known as the spinal cord. Individual nerves, such as those carrying messages to the arms or legs, enter and exit the spinal cord through gaps between vertebrae. 
     The spinal discs act as shock absorbers, cushioning the spine, and preventing individual bones from contacting each other. Discs also help to hold the vertebrae together. The weight of the upper body is transferred through the spine to the hips and the legs. The spine is held upright through the work of the back muscles, which are attached to the vertebrae. 
     A number of approaches, systems, and apparatuses have been devised to accomplish a variety of surgical interventions in association with the spine. These approaches enable a surgeon to place instrumentation and implantable apparatuses related to discectomy, laminectomy, spinal fusion, vertebral body replacement and other procedures intended to address pathologies of the spine. The variety of surgical approaches to the spine have a number of advantages and drawbacks such that no one perfect approach exists. A surgeon often chooses one surgical approach to the spine from a multitude of options dependent on the relevant anatomy, pathology, and a comparison of the advantages and drawbacks of the variety of approaches relevant to a particular patient. 
     A common surgical approach to the spine is the lateral approach, which, in general, requires a surgeon to access the spine by creating a surgical pathway through the side of the patient’s body through the psoas muscle to an intervertebral disc space where it is possible to dock onto the lateral lumbar disc. Variants of the lateral approach are commonly referred to as the “direct lateral” approach in association with the “DLIF” procedure, the “extreme lateral” approach in association with the “XLIF” procedure, and the “oblique lumbar” approach in association with the “OLIF” procedure. 
     A common problem associated with the lateral surgical approach includes a significant risk of damage to the musculature surrounding the spine.  FIGS.  1 A- 1 B  illustrates a partial view of a spine  100  comprised of sequential vertebrae  109 , each separated by intervertebral disc space  110 , with an attached psoas muscle group  102  (including the psoas minor and psoas major). As shown, the psoas muscle  102  runs generally in a cranial-caudal direction with muscle fibers attached diagonally or at an approximate 45-degree angle to the spine  100 .  FIGS.  2 A- 2 B  illustrate an exemplary lateral approach to the spine. In typical lateral approaches, after making an incision in the psoas muscle  102 , the surgeon places a number of sequential circular dilators  104   1-n , each larger in diameter, on the desired pathway to the spine  100  through the psoas muscle  102  to dilate the surgical site radially away from the initial incision site or K-wire insertion point. This dilation process can lead to compression of muscle, nerves, and blood supplies adjacent to the vertebral body, which can lead to ipsilateral upper thigh pain, hip flexor weakness that causes difficulty in walking and/or stair climbing, and muscle atrophy that follows from muscle injury. 
     After the series of circular dilators are forced into the muscle tissue, a multi-bladed or tubular retractor apparatus  106  may be placed over the final dilator  104   n . The retractor is then retracted radially to separate the psoas muscle and other soft tissues. A common problem associated with this type of lateral procedure is that soft tissues, including the musculature and nerves surrounding the spine, become crushed and/or trapped near the distal end of the retractor’s blades when the retractor is passed over the final dilator, a problem often referred to as “trappage,” graphically depicted in  FIG.  3   . 
     In order for the surgeon to clear the surgical pathway to the disc space, or to “see” the disc space, the surgeon must cauterize and cut the muscle that is caught inside the retractor, effectively performing a muscle biopsy each time the surgeon performs an XLIF, DLIF, OLIF procedure. Beyond undesired muscular damage to the patient, this approach requires additional effort for the surgeon to utilize a cautery or similar device to remove the trapped soft tissues from between the distal end of the retractor and the vertebral bodies prior to completing access to the spine. 
     Oftentimes the resulting damage and trauma to the soft tissue resulting from trappage and removal of psoas muscle tissue with a cautery causes lasting problems for a patient. For instance, a patient who experiences trappage during surgery will often have ipsilateral upper thigh pain and leg weakness. Such pain and leg weakness occurs due to the linkage of the psoas to the lower body, as the psoas muscle connects to the femur. Thus, damage to the psoas will generally manifest in lower body discomfort, including pain and weakness in the leg. 
     Another problem associated with existing lateral surgical approaches to the spine is nerve damage. The lumbar plexus is a web of nerves (a nervous plexus) in the lumbar region of the body which forms part of the larger lumbosacral plexus. The lumbar plexus in particular is often damaged as a direct result of surgical intervention utilizing the lateral approach to the spine. The nerves associated with the lumbar plexus can experience indirect nerve injury as a result of over-dilation or over-retraction of apparatuses utilized to accomplish lateral access to the spine. They also can experience direct nerve injury as a result of direct trauma caused by impingement from the instrumentation utilized during the surgical intervention in association with the lateral approach to the spine, as in the case of trappage, discussed above. Such indirect and direct nerve damage can cause numbness in part or all of the leg and can lead to indirect muscle atrophy. A recent meta-analysis review of 24 published articles indicates that the lateral approach is associated with up to a 60.7% complication rate. Gammal, Isaac D, et. al, Systemic Review of Thigh Symptoms after Lateral Transpsoas Interbody Fusion for Adult Patients with Degenerative Lumbar Spine Disease, International Journal of Spine Surgery 9:62 (2015). The review further found that the retractors resulted in 43% psoas muscle pain, 30.8% psoas muscle weakness, and 23.9% nerve or plexus injury due to the inherently flawed design of existing commercially available retractors. 
     One existing method of neuromonitoring involves the insertion of a number of epidural electrodes into the lumbar plexus. Stimulation of the electrodes is used to trigger a response in the patient’s nerve structures, and the resulting evoked potentials correspond to the neural activities of the nerve structures near the recording electrodes. The potentials may be recorded to detect reactions in the nervous system that may indicate a problem, including some type of impingement or encroachment of an instrument upon the nerve structures during a procedure. This method, while providing information relating to a change in the behavior of the nerve structures nearby the inserted electrodes, does not directly correlate to a change in the behavior of the nerve structures in response to a nearby surgical instrument such as a dilator or a retractor, and is therefore not optimal for identifying impingement from the instrumentation utilized during the surgical intervention. 
     In addition, existing dilators oftentimes incorporate a vertical wire conductor that extends through the outer wall of the dilator parallel to the longitudinal axis of the apparatus, terminating in a pinpoint electrode at the distal end of the apparatus. The electrode may stimulate nearby nerve structures to asses for any impingement upon nerve or plexus. Because the vertical wire provides only a pinpoint electrode, the surgeon must manually rotate the apparatus through 360 degrees to perform a full range of neuromonitoring for impingement upon all of the adjacent neurological structures surrounding the device: the front and the back, superior and inferior. This additional step is cumbersome and presents challenges in achieving thorough neuromonitoring. Moreover, because existing dilators with pinpoint electrodes require the surgeon to rotate the dilators to achieve neuromonitoring in 360 degrees, the dilators cannot perform a full range of monitoring once they are affixed. After fixation, only pinpoint monitoring is provided, and existing devices cannot provide continuous, real-time neuromonitoring throughout the procedure. 
     Existing retractor systems also present challenges in terms of illumination and require a separate light source that attaches to the top of the retractor. This separate device is cumbersome, physically interfering and disruptive, and the limited ability to position the light source oftentimes means that light reflects off of the retractor blades before returning to the surgeons eyes, which leads to suboptimal visualization of the surgical area. 
     Existing retractor systems also lack ease of adjustability and are not designed with an eye toward ergonomic use by the surgeon, who is forced to hunch over the retractor apparatus during the course of the procedure to direct the surgical equipment as desired. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key aspects or essential aspects of the claimed subject matter. Moreover, this Summary is not intended for use as an aid in determining the scope of the claimed subject matter. 
     One embodiment provides a lateral retractor system for forming a lateral retractor system for forming a surgical pathway through a plurality of psoas muscle fibers to a patient’s intervertebral disc space, comprising a dilator including a conductive body extending between a proximal end and a distal end; a first nonconductive layer disposed upon an outer surface of the conductive body; a first active neuromonitoring tip protruding from the distal end of the conductive body to a leading distal edge configured for insertion into the intervertebral disc space; and a first conductive electrical pathway extending from a first conductive input surface at the proximal end of the conductive body, through the conductive body, and to the first active neuromonitoring tip such that an electrical signal applied to the first conductive input surface causes the first active neuromonitoring tip to simultaneously and continuously stimulate one or more nerve structures located adjacent to any portion of a circumference of the distal end of the conductive body to assess for an encroachment of the dilator upon the one or more of the nerve structures. 
     Another embodiment provides a dilation system for minimizing damage to a patient’s psoas muscle fibers when forming a surgical pathway to an intervertebral disc space of the patient’s spine, the dilation system having a dilator including a conductive body portion extending between a proximal end and distal end; a nonconductive layer disposed upon the conductive body portion; and a conductive neuromonitoring portion extending distally from the distal end of the conductive body portion to a leading distal edge configured for insertion between the patient’s psoas muscle fibers, wherein when an electrical dilator stimulus is applied to the proximal end of the conductive body portion, the electrical dilator stimulus propagates through the conductive body portion to the conductive neuromonitoring portion such that the conductive neuromonitoring portion simultaneously stimulates one or more nerve structures located adjacent to any point about a circumference of the conductive neuromonitoring portion. 
     Yet another embodiment provides retraction system for forming a surgical pathway through a patient’s psoas muscle to the patient’s intervertebral disc space, comprising a dilator for traversing a plurality of fibers of the patient’s psoas muscle, the dilator having a dilator body portion and a dilator neuromonitoring portion extending distally from the dilator body portion; a retractor having retractable blades configured to pass over the dilator, each of the retractable blades having a blade body portion and a blade neuromonitoring portion extending distally from the blade body portion, wherein the dilator and each of the blades are conductive such that an electrical dilator stimulus applied to the dilator body portion propagates to the dilator neuromonitoring portion and an electrical blade stimulus applied to the blade body portion of each of the retractable blades propagates to each of the blade neuromonitoring portions to simultaneously and continuously stimulate one or more nerve structures located adjacent to any portion of a circumference of the dilator neuromonitoring portion and any portion of a circumference of each of the blade neuromonitoring portions to assess for an encroachment of the dilator and the dual-blade retractor upon the one or more of the nerve structures; and an insulative dilator nonconductive layer disposed upon the dilator body portion, and an insulative blade nonconductive layer disposed upon each of the blade body portions. 
     Other embodiments are also disclosed. 
     Additional objects, advantages and novel features of the technology will be set forth in part in the description which follows, and in part will become more apparent to those skilled in the art upon examination of the following, or may be learned from practice of the technology. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present invention, including the preferred embodiment, are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. Illustrative embodiments of the invention are illustrated in the drawings, in which: 
         FIGS.  1 A- 1 B  illustrate perspective and top partial views, respectively, of a patient’s spine comprised of sequential vertebrae, each separated by an intervertebral disc space, with an attached psoas muscle group; 
         FIGS.  2 A- 2 B  illustrate perspective views of a prior art retraction system including a series of increasing-diameter dilators and a circular lateral retractor, as inserted into the spine of  FIGS.  1 A- 1 B ; 
         FIG.  3    illustrates a bottom-plan view of the prior art dilators and lateral retractor of  FIGS.  2 A- 2 B , as inserted into the psoas muscle and trapping the muscle fibers; 
         FIGS.  4 - 6    illustrate respective perspective, top, and front views of one embodiment of a rectangular dilator, as inserted at an insertion orientation through a patient’s side body and through the psoas muscle over the intervertebral disc space of  FIGS.  1 A- 1 B ; 
         FIG.  7    illustrates a perspective view of the rectangular dilator of  FIGS.  4 - 6   ; 
         FIG.  8    illustrates a perspective view of the rectangular dilator of  FIGS.  4 - 6   , as inserted at the insertion orientation through the psoas muscle over the intervertebral disc space and having a monitor cable coupled with a conducting wire in electronic communication a neuromonitoring tip of the dilator; 
         FIGS.  9 - 10    illustrate perspective and side views, respectively, of one embodiment of a dual-blade assembly passed over the inserted dilator of  FIGS.  4 - 8    in the insertion orientation; 
         FIGS.  11 - 14    illustrate left-perspective, right-perspective, top-plan, and left-bottom-perspective views, respectively, of one embodiment of a blade subassembly of the dual-blade assembly of  FIGS.  9 - 10   ; 
         FIG.  15    illustrates a perspective view of the dual-blade assembly of  FIGS.  9 - 10    installed in the insertion orientation, without a lower coupling device and disposed upon a surgical table in preparation for connection with a lateral retraction gearbox; 
         FIG.  16    illustrates a perspective view of the dual-blade assembly of  FIGS.  9 - 10    including a lower coupling device attaching two of the blade subassemblies of  FIGS.  11 - 14   , in preparation for connection with the lateral retraction gearbox of  FIG.  15   ; 
         FIG.  17    illustrates a perspective view of the dual-blade assembly of  FIG.  16    in the insertion orientation, connected to the lateral retraction gearbox of  FIGS.  15 - 16    via one embodiment of a rotation assembly; 
         FIG.  18    illustrates a perspective view of the connected dual-blade assembly, lateral retraction gearbox, and rotation assembly of  FIG.  17   , with the dual-blade assembly rotated to a final rotated orientation via the rotation assembly; 
         FIG.  19    illustrates a perspective view of one embodiment of a rotation gearbox and connecting rods of the rotation assembly of  FIGS.  17 - 18   ; 
         FIG.  20    illustrates a perspective view of the connected dual-blade assembly, lateral retraction gearbox, and rotation assembly of  FIGS.  17 - 18   , with a handle of the rotation assembly removed and an embodiment of a pair of opposing passive lateral arms coupled between the dual-blade assembly and the lateral retraction gearbox; 
         FIG.  21    illustrates the assembly of  FIG.  20   , with a gearbox of the rotation assembly removed; 
         FIG.  22    illustrates a perspective view of the assembly of  FIG.  21   , with one embodiment of a pair of opposing lateral drive arms coupled between the dual-blade assembly and the lateral retraction gearbox; 
         FIG.  23    illustrates a perspective view of the assembly of  FIG.  22   , with a K-wire and a lower coupling device removed from the dual-blade assembly to an exploded position; 
         FIG.  24    illustrates a perspective view of the assembly of  FIG.  23   , with the dilator of  FIGS.  4 - 8    removed to an exploded position; 
         FIG.  25    illustrates a perspective view of the assembly of  FIG.  24   , with a housing of the lateral actuation gearbox removed to reveal one embodiment of a lateral retraction gear chain operating within the housing; 
         FIGS.  26 - 27    illustrate top views of two adjacent blade subassemblies of  FIGS.  11 - 14    coupled with one embodiment of a lateral retraction assembly and in a closed blade position; 
         FIGS. URS  28 - 30    illustrate top views of the two blade subassemblies coupled with the lateral retraction assembly of  FIGS.  26 - 27    in a retracted blade position; 
         FIG.  31    illustrates a perspective view of the two blade subassemblies coupled with the lateral retraction assembly in the retracted blade position of  FIG.  30   , as inserted through the patient’s side body; 
         FIG.  32    illustrates a perspective view of one embodiment of a fully assembled lateral retraction system; 
         FIG.  33    illustrates a perspective view of a surgical area illuminated using LEDs built into one embodiment of the lateral retraction system of  FIG.  32   ; 
         FIG.  34    illustrates a perspective view of an image area covered by a video camera incorporated within one embodiment of the lateral retraction system of  FIG.  32   ; 
         FIGS.  35 A- 35 B  provide a flowchart depicting an exemplary method of creating a surgical pathway to the patient’s spine using the assemblies and systems of  FIGS.  4 - 34     
         FIGS.  36 A- 36 B  illustrate perspective and cross-sectional views of another embodiment of a planar dilator featuring non-wired, continuous, and simultaneous neuromonitoring about 360-degrees of a circumference of the dilator; and 
         FIGS.  37 A- 37 F  illustrate respective front, rear, partial-rear-perspective, partial-side-perspective, unassembled partial-rear perspective, and assembled partial-rear perspective views of one embodiment of a blade and adjustable wings for incorporation into the blade subassembly of  FIGS.  11 - 18   , featuring non-wired, continuous, and simultaneous neuromonitoring about 360-degrees of a circumference of the blade and the adjustable wings. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments are described more fully below in sufficient detail to enable those skilled in the art to practice the system and method. However, embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. The following detailed description is, therefore, not to be taken in a limiting sense. 
     This disclosure details a system and method of use for a lateral approach to creating a minimally invasive surgical pathway through a patient’s side body and psoas muscle  102  to the intervertebral disc space  110  of the spine  100 . Embodiments may include a lateral retractor system having a flat, narrow dilator having a body that tapers to a distal edge. The dilator inserted in a diagonal orientation that is parallel to the angled fibers of the psoas muscle and anchored into the disc space  110  via a K-wire. The dilator may be used in conjunction with a dual-blade lateral retractor that may be placed in a corresponding diagonal orientation over the flat, narrow dilator before the entire system is rotated approximately 45-50 degrees to the horizontal, or until the dilator and the lateral retractor are parallel with the disc space  110 , as shown and discussed in  FIGS.  17 - 18    below. Once the system is rotated, the dilator may be removed and the dual blades of the lateral retractor may be laterally separated to push the muscle fibers away and to complete the surgical pathway in a manner that minimizes entrapment of, impingement upon, and/or damage to the patient’s muscle fibers and nerve structures. Because the dilator is narrow or flat in shape, which allows the dilator to be placed in its insertion orientation parallel to the muscle fibers and then rotated to its final rotated orientation parallel to the disc space, the system functions with a single element or component dilator, rather than requiring placement of a series of sequentially larger circular dilators, as discussed in the Background section above. 
     Both the dilator and the lateral retractor may incorporate real-time,  360  degree neuromonitoring through stimulated horizontal wiring positioned on the external sides/surfaces of each of the distal dilator tip and the distal ends of the blades of the lateral retractor, enabling real-time and continuous neuromonitoring throughout the procedure from front to back and superior to inferior. Embodiments of the lateral retractor system may also incorporate built-in LED lighting for superior surgical visualization, as well as micro-video capabilities that enable the system to be operated in the most ergonomic and efficient fashion. 
     Turning to exemplary embodiments,  FIGS.  4 - 34  and  35 A- 35 B  generally illustrate a method of using embodiments of a disclosed lateral retractor system  200  ( FIG.  32   ) to employ a lateral surgical approach to clear a surgical pathway  114  to a patient’s spinal disc space  110 . Specifically and in one embodiment,  FIGS.  4 - 34    detail a number of steps in which exemplary devices are in use to create the surgical pathway  114  through the side of a patient’s body  108 , through the psoas muscle  102 , and to the intervertebral disc space  110 , while  FIGS.  35 A- 35 B  provide a flowchart depicting an exemplary method  500  of creating the surgical pathway  114  through the side of the patient’s body  108  through the psoas muscle  102  to the disc space  110 . 
     Employing fluoroscopy imaging technology, a dilator  202  may be placed over/adjacent to the intervertebral disc space  110  ( FIG.  35 A ,  501 ). Specifically, and referring to  FIGS.  4 - 7   , the dilator  202  may enter through an incision  118  in the patient’s side body  108  ( FIG.  35 A ,  502 ), cut through any intervening fascia ( FIG.  35 A ,  504 ), and then traverse the psoas muscle  102  in a direction, or at an insertion orientation  239 , that is “along,” or parallel to the muscle fibers of the psoas muscle  102 , and diagonal to, or angled at approximately 45 degrees to, the patient’s spine  100  ( FIG.  35 A ,  506 ). The psoas muscle  102  may be accessed via the side of the patient’s body  108  such that the dilator  202  protrudes from a lateral surface  116  of the patient’s body  108  when inserted to full depth at the spinal column  100 . 
       FIG.  7    illustrates a perspective view of one embodiment of the dilator  202 . In this embodiment, the dilator  202  may feature a flat, narrow body  204  having opposing flat surfaces  209  that extend between a proximal end  206  for positioning at the lateral surface  116  of the patient’s side body  108  ( FIG.  4   ) and a distal end  208  for positioning adjacent the patient’s spine  100 . The longitudinal sides of the narrow body  204  of the dilator  202  may taper to opposing longitudinal edges  212 , and the distal end  208  of the dilator  202  may taper to a distal edge  210  capable of cutting through the patient’s fascia and traversing the fibers of the psoas muscle  102  in the parallel manner described above. As a result, the dilator  202  separates, rather than crushes, the fibers of the psoas muscle  102  as it traverses through the psoas muscle  102  to the spine  100 , as shown in  FIGS.  4 - 6  and  8   . 
     The dilator  202  may also include a K-wire access aperture  216  that extends longitudinally through the body  204  of the dilator  202 . In addition, conducting wires  218  may extend longitudinally through each side of the body  204  of the dilator  202 . At the distal end  208  of the dilator  202 , the conducting wires  218  may be in electronic communication with a set of horizontal neurosensing wires  220  that are integrated or built into each side of the tapered distal end  208  of the dilator  202 . At the proximal end  206  of the dilator, the conducting wires  218  may be in electronic communication with a monitoring cable  224 , shown in  FIG.  8   , which may be configured to conduct an electronic stimulus through the conducting wires  218  to the horizontal neurosensing wires  220 , forming an active neuromonitoring tip  222  about an entirety of the distal end  208  of the dilator  202 . 
     Impingement of the active monitoring tip  222  upon, or alternatively, encroachment of the active monitoring tip  222  in close proximity to nerve structures located along the patient’s spine  100  may stimulate those nerve structures that are nearby or adjacent to the active monitoring tip  222 . The voltage of the applied electronic stimulus may be adjusted as necessary and/or required to stimulate nerve structures within a defined distance of the active monitoring tip  222 . This applied stimulus causes the nerve structure(s) to fire and generate a responsive signal, which may in turn be conducted from the active monitoring tip  222 , through the conducting wires  218 , and to the monitoring cable(s)  224  in electronic communication with one or both of the conducting wires  218  at the proximal end  206  of the dilator  202 , as shown in  FIG.  8   , thereby translating the neurosensing stimulation of the active monitoring tip  222  by the nearby nerve structure(s) to external monitoring equipment (not shown) via the monitoring cable  224  and determining, in real time and with 360 degrees of monitoring range or field of view about the distal end  208  of the dilator  202 , a possibility of nerve or plexus injury as the dilator  202  is inserted ( FIG.  35 A ,  508 ). 
     Embodiments of the dilator  202  and its components may be formed of any appropriate conductive or nonconductive, autoclavable or otherwise sterilizable metal or plastic. In addition, the body  204  of the dilator  202  may have any appropriate length to accommodate the patient’s size, shape, and/or physiology. In one embodiment, the dilator  202  may be provided in a variety of lengths, allowing the surgeon to select in real-time the appropriate length for the patient. 
     Once the distal edge  210  of the dilator  202  is positioned at the spine  100  in the insertion orientation  239  that is parallel to the fibers of the psoas muscle  102  and spanning the disc space  110  diagonally at an approximate 45-degree angle, a K-wire  214  may be passed longitudinally through the access aperture  216  of the dilator  202  and into the spine  100  at the disc space  110  ( FIG.  35 A ,  510 ), both stabilizing and securing the position of the dilator  202 , as shown in  FIGS.  6  and  8   . Because of the active monitoring tip  222 , the full range of monitoring - front to back and superior to inferior - may continue after the dilator  202  is fixed via the k-wire  214 . Unlike previous devices featuring pinpoint electrodes that require manual rotation to perform 360 degrees of monitoring, the active monitoring tip  222  remains active and provides a geometry capable of monitoring in 360 degrees during every stage of its insertion and use during a procedure. 
     Referring to  FIGS.  9 - 10   , after securing the K-wire  214  ( FIG.  35 A ,  510 ) into the disc space  110  of the spine  100  such that the dilator  202  is stabilized, secured, and providing continuous neuromonitoring, a dual-blade assembly  230  of a dual-blade lateral retractor system  200  ( FIG.  32   ) may be passed over or introduced at the insertion orientation  239  alongside the dilator  202  such that each blade  244  of the dual-blade assembly  230  opposes and contacts one of the opposing flat surfaces  209  of the dilator  202  to further minimize damage to nerve structures and muscle fibers ( FIG.  35 A ,  512 ). 
     As shown in  FIGS.  9 - 10   , the dual-blade assembly  230  may include two opposing and identical blade subassemblies  240  coupled to one another via a lower coupling device  242  configured to snap or press fit into receiving structures formed within each of the blade subassemblies  240 . The lower coupling device  242  may include a platform  241  having a plurality of protrusions extending from a bottom of the platform  241  that are sized to be received by each of the blade subassemblies  240 . The protrusions may include two opposing rectangular protrusions  243  and four opposing circular protrusions  245 , each for insertion into a corresponding one of the blade subassemblies  240 . The lower coupling device  242  may also include two circular receivers  247  formed within a top of the platform  241  and configured to receive components of additional functional assemblies that stack above the blade assembly  230 , as detailed further below. 
       FIGS.  11 - 13    illustrate front-perspective, rear-perspective, and top-plan views of one exemplary embodiment of the blade subassembly  240 , respectively. ln this embodiment, the blade subassembly  240  may include a blade  244  having a planar inner surface  235  that faces the opposing blade  244  of the dual-blade assembly  230  ( FIGS.  9 - 10   ), an outer surface  237 , a proximal blade portion  246 , a detachable distal blade portion  248 , and opposing longitudinal edges  250  that extend between a proximal end  260  of the proximal blade portion  246  and a distal end  255  of the distal blade portion  248 . Opposing adjustable wings  252  may be hingedly coupled with each of the opposing longitudinal edges  250 , as detailed further below. 
     Turning to the blade  244 , the detachable distal portion  248  may be a disposable, single-use insert of any appropriate length to accommodate the patient’s size or physiology. In one embodiment, a plurality of detachable distal portions  248  may be provided in a peel pack (not shown), where each of the distal portions  248  contained within the peel pack feature a different length to accommodate a variety patient sizes and/or physiologies, which results in a variety of distances to traverse between the lateral surface  118  of the patient’s body  108  and the spine  100 . During use, the surgeon may select the detachable distal blade portion  248  with the appropriate length before attaching the select distal blade portion  248  to the reusable and sterilizable proximal portion  246  of the blade  244 . The detachable distal portion  248  may attach to the reusable proximal portion  246  in any appropriate manner including, for example, a snap-fit of mating components or, as shown in  FIG.  12   , via an attachment screw  254  or another appropriate threaded fastener. 
     In one embodiment, the distal end  255  of the distal portion  248  of the blade  244  may form an active monitoring tip  256  similar to the active monitoring tip  222  of the dilator  202 . In this regard, horizontal neurosensing wires  258  may be incorporated or built into the outer surface  237  of the blade  244  at the active monitoring tip  256 . The horizontal neurosensing wires  258  may detect any impingement or encroachment upon nerve or plexus, and the resulting stimulus may be conducted through conducting wires embedded longitudinally in the blade, and through a monitoring cable for reporting to external equipment. Via the active monitoring tip  256  of each of the distal blade portions  248  of the blades  244 , continuous real-time neuromonitoring may be performed to prevent nerve or plexus injury when the blade assembly  230  is inserted over the dilator  202  ( FIG.  35 A ,  512 ,  514 ), as well as when the blade assembly  230  is rotated ( FIG.  35 A ,  516 ) and/or laterally separated or retracted ( FIG.  35 A ,  524 ), as discussed below. Unlike existing systems, neuromonitoring over a full 360-degree monitoring range may continue throughout the procedure. 
     The sterilizable and reusable proximal blade portion  246  may include a number of unique features that aid the surgeon. In one embodiment, the proximal end  260  of the proximal blade portion  246  may form a generally rectangular receiver  262  configured to receive one of the rectangular protrusions  243  of the lower coupling device  242  ( FIGS.  9 - 10   ), which is adapted to temporarily couple the dual, opposing blade subassemblies  240  to one another during insertion and assist in rotating the blade subassemblies  240  from the insertion orientation  239  to a final, rotated orientation, as discussed below in relation to  FIGS.  17 - 18   . 
     In addition, and referring to  FIGS.  11 - 14   , one or more light emitting diode (LED) lights  264  may be built into the proximal blade portion  246 . As shown in  FIGS.  11  and  14    and in this embodiment, three LED lights  264  may be positioned adjacent to the inner surface  235  of a distal end  261  of the proximal blade portion  246 , such that the LED lights  264  illuminate a surgical area  266 , as shown in  FIG.  11   . In one embodiment shown in  FIG.  14   , the LED lights  264  may be mounted to a printed circuit board (PCB)  265  housed within a PCB chamber  267  formed within the proximal blade portion  246  of the blade  244 . The PCB  265  may incorporate control or interface circuitry that is, in turn, electrically coupled with a power source and a switch  272 . In this embodiment, the power source may be one or more lithium ion batteries  268  housed within a battery housing  270  that is affixed in any appropriate manner to the outer surface  237  of the blade  244 , as shown in  FIGS.  11 - 13   . The switch  272  may be electrically coupled between the batteries  268  and the PCB 265/LED lights  264 , such that the switch  272  is configurable to control the lights  264  as necessary and/or desired by the surgeon. For example, the switch may be operated to illuminate a single one of the LED lights  264 , a pair of the lights  264 , or all of the LED lights  264  depending on the applicable light requirements and/or requisite run times. 
     Built-in lighting on the inner surfaces  235  of the blades  244  provides more accurate visualization for the surgeon due to the proximity of the light emitting source to the surgical field  266 . The built-in lighting also eliminates the need for an external extension cord for lighting purposes, and prevents light projected from a separately attached light source, which is often attached to a proximal end of the apparatus, from reflecting off the blades and into the surgeon’s eyes during operation. 
     The blade  244  may also include video capability to provide ergonomic operation for the surgeon. Specifically, and in one embodiment shown in  FIG.  14   , an interior of the proximal blade portion  246  may form a camera receiver channel  274  into which a video camera  276  (e.g., a commercially available micro-video camera) may be fed or positioned to provide a clear view of the surgical field  266 . Images captured by the video camera  276  may be transmitted to one or more external monitors (e.g., flat screen television monitors) (not shown) via a video output  278  electronically coupled between the video camera  276  and the monitor(s). In one embodiment, the video camera  276 /video output  278  may employ wireless technology such as, for example, a Bluetooth, Zigbee, Wi-Fi or another appropriate transmitter or transceiver to communicate with the external monitoring devices. This video capability enables the surgeon to view his or her work within the surgical field  266  inside the dual-blade assembly  230  on the external monitors, and relieves the surgeon of the need to look straight down the assembly throughout the course of the procedure being performed. 
     As discussed above, each of the longitudinal edges  250  of the blade  244  may hingedly couple with an adjustable wing  252 , as shown in  FIGS.  11 - 14   . As detailed below in relation to  FIGS.  25 - 31   , the adjustable wings  252  may be rotated or adjusted through 90 degrees relative to the inner surface  235  of the blade  244  - from an open position  280  that is parallel with the blade  244  ( FIGS.  25 - 27   ) to a closed position  282  that is perpendicular to the blade  244  ( FIG.  30   ), and any position therebetween ( FIGS.  28 - 29   ). This adjustment from the open position  280  to the closed position  282  essentially sections off the muscle surrounding the dual-blade assembly  230  as the blades  244  are separated or retracted away from one another, thereby preventing any “creep” of the muscle between the blades during retraction and enabling the dual-blade assembly  230  to accomplish what has previously required additional blades (e.g., multiple blades beyond two, a circular or radial blade configuration) to complete. 
       FIGS.  12 - 13    illustrate a perspective view of the blade subassembly  240  and a top view of the blade subassembly  240  with the battery housing  270  removed, respectively. Specifically,  FIGS.  12 - 13    detail an exemplary actuation assembly  290  for the adjustable wings  252  on each blade  244 . ln this embodiment, the actuation assembly  290  may include a central miter gear  292  positioned horizontally such that a center axis  294  defined by the central miter gear  292  runs parallel to the blade  244 . A top of the central miter gear  292  may form a hexagonal socket  296  configured to receive an actuating hex key (not shown), which may take the form of a removeable manual handle such as handles  310  and  316 , discussed below in relation to the rotation and lateral retraction assemblies. 
     The central miter gear  292  may be enmeshed between two opposing vertical miter gears  298 , each defining a center axis  300  that is perpendicular to and that intersects the center axis  294  of the central miter gear  292 . Each of the vertical miter gears  298  may be affixed to a worm screw  302  that is, in turn, enmeshed with a corresponding worm wheel  304  affixed to a proximal end of the associated adjustable wing  252 . To operate, the hex key/handle may be rotated within the hexagonal socket  296  to rotate the central miter gear  292 , which, in turn rotates the vertical miter gears  298 , the attached worms screws  302 , and the corresponding worm wheels  304  affixed each adjustable wing  252  to move the wings  252  through 90 degrees in the direction of arrow C relative to the inner surface  235  of the blade  244 , as shown in  FIGS.  25 - 31   . 
     Like the lower blade portion  248 , the adjustable wings  252  may be single-use components that vary in length based upon an overall length of the blade  244  required to accommodate the patient’s size and/or shape. Moreover, each of the adjustable wings  252  may form an active monitoring tip  283  ( FIG.  12   ) on its outer surface similar to the active monitoring tips  222  and  256  of the dilator  202  and the blade  244 , respectively. 
     Returning to the method and in relation to  FIGS.  15 - 19   , after the dual-blade assembly  230  is passed over the dilator  202  in a direction along the fibers of the psoas muscle  102  ( FIG.  35 A ,  512 ), the dual-blade assembly  230  may be rotated approximately 45-50 degrees in the direction of arrow A about the K-wire  214 , from its initial insertion orientation  239  parallel to the fibers of the psoas muscle  102 , shown in  FIGS.  15 - 17   , to a final rotated orientation  306  parallel to the disc space  110 , in which the blades  244  of the dual-blade assembly  230  are positioned transverse to the fibers of the psoas muscle  102  and begin to separate the fibers of the psoas muscle  102 , as shown in  FIG.  18    ( FIG.  35 B ,  516 ). 
     To rotate the dual-blade assembly  230  from the insertion orientation  239  to the rotated orientation  306  ( FIG.  35 B ,  516 ), additional assemblies may be operably coupled with the dual-blade assembly  230 , as shown in  FIGS.  15 - 19   . Initially, a lateral actuation gearbox  308  and an actuating handle  310  may be securely attached to a fixed reference point such as a surgical table  233  via a standard tooth jaw and universal joint mechanism (not shown) ( FIG.  35 B ,  518 ), as shown in  FIG.  15   . Then a rotation assembly  312  may be coupled between the blade assembly  230  and the lateral actuation gearbox  308  ( FIG.  35 B ,  520 ). 
     In further detail and in one embodiment shown in  FIGS.  17 - 19   , the rotation assembly  312  may include a rotation gearbox  314 , an actuating handle  316 , and a pair of connecting rods  318  coupled between the rotation gearbox  314  and the lateral actuation gearbox  308 , each having a first end  320  affixed to the a housing  324  of the rotational gearbox  314  and a second end  322  affixed to a housing  342  of the lateral actuation gearbox  308 . The first and second ends  320 ,  322  of the connecting rods  318  may be affixed to the rotational gearbox housing  324  and the lateral actuation gearbox housing  342 , respectively, in any appropriate manner including, for example, via threaded fasteners. 
       FIG.  19    illustrates a perspective view of one embodiment of the rotation gearbox  314  and the connecting rods  318 , with the housing  324  of the rotation gearbox  314  in which the housing  324  is shown in wireframe to reveal the details of the gearbox  314 . In this embodiment, the rotation gearbox  314  may contain first, second, and third rotational gears  326 ,  328 ,  330 , respectively, that are rotationally mounted relative to one another within the housing  324 . The first rotational gear  326  may include a hexagonal or other appropriately configured socket  332  adapted to receive a distal end of the handle  316 , which, in this embodiment, may be configured as a hex key. The third rotational gear  330  may be affixed to an upper coupling device  334  having a top surface  336  adapted to attach to the third rotational gear  330  and a bottom surface  338  having two circular protrusions  340  extending therefrom. Each of the circular protrusions  340  may, when the rotation gearbox  314  is assembled to the blade assembly  230  as shown in  FIGS.  17 - 18   , extend into the circular receivers  247  of the lower coupling device  242  of the blade assembly  230 , shown in  FIG.  16    and detailed above in relation to  FIGS.  9 - 10   . 
     Once the rotation assembly  312  is coupled between the blade assembly  230  and the lateral actuation gearbox  308  ( FIG.  35 B ,  520 ), as shown in  FIG.  17   , the handle may be manually actuated ( FIG.  35 B ,  522 ) to turn the first rotational gear  326 , which, in turn, rotates the enmeshed second rotational gear  328  and then the enmeshed third rotational gear  330 . Because the lateral actuation gearbox  308 , the connecting rods  318 , and the rotation gearbox  314  are fixed relative to the operating table (not shown), rotation of the third rotational gear  330  causes the upper coupling device  334  to turn the attached lower coupling device  242  about the K-wire  214 , which causes the two attached blade subassemblies  240  to rotate in the direction of arrow A ( FIGS.  15 - 16   ) from the initial insertion orientation  239  of  FIG.  17    to the final rotated orientation  306  of  FIG.  18   . 
     After the dual-blade assembly  230  has been rotated into the final rotated orientation  306  ( FIG.  35 B ,  516 ), the system may be reconfigured for separation, or lateral retraction, of the two opposing blade subassemblies  240  via the steps illustrated in  FIGS.  20 - 25    ( FIG.  35 B ,  524 ). First, and as shown in  FIG.  20   , a pair of opposing passive lateral arms  344  may be attached between the lateral actuation gearbox  308  and the battery housings  270  of the blade subassemblies  240  ( FIG.  35 B ,  526 ). Each of the passive lateral arms  344  may have a first end  346  that is rotationally coupled with one of the battery housings  270  and a second end  348  that is rotationally coupled with the housing  342  of the lateral actuation gearbox  308 , such that the passive lateral arms  344  may provide stabilization to the blade assembly  230  as the rotation gearbox  314  is removed, as shown in  FIG.  21   , as well as passively accommodate the lateral separation of the blade subassemblies  240 , as discussed further below in relation to  FIGS.  26 - 31   . The rotational couplings between the passive lateral arms  344 , the battery housings  270 , and the lateral actuation gearbox  308  may take any appropriate shape, configuration, or type. In this embodiment, the first and the second ends  346 ,  348  of each of the passive lateral arms  344  may form a receiver  350  configured to receive a corresponding protrusion  352  extending from the battery housing  270  and from the lateral actuation gearbox  308  via a friction fit. 
     Once the passive lateral arms  344  are attached ( FIG.  35 B ,  526 ), the rotation assembly  312 , including the rotation gearbox  314 , the manual handle  316 , and the connecting rods  318 , may be removed as shown in  FIGS.  20 - 21    by disengaging the upper and the lower coupling devices  334  and  242 , all the while relying on the passive lateral arms  344  for stabilization of the blade assembly  230  during removal ( FIG.  35 B ,  528 ). Then a pair of opposing lateral drive arms  354  may be coupled between the lateral actuation gearbox  308  and the battery housings  270  of the blade subassemblies  240  ( FIG.  35 B ,  530 ), as shown in  FIG.  22   . Each of the lateral drive arms  354  may have a first end  356  that is rotationally coupled to one of the battery housings  270  of the blade subassemblies  240  and a second end  358  that is rotationally coupled to the housing  342  of the lateral actuation gearbox  308 . These rotational couplings may take any appropriate form, though in one embodiment, they may mimic the structure of the rotational couplings of the passive lateral arms  344  in that each of the first and the second ends  356 ,  358  may form a receiver  360  configured to receive a corresponding protrusion  362  extending from the battery housing  270  and from the lateral actuation gearbox housing  342 , respectively, via a friction fit. 
     After the lateral drive arms  354  are attached, the K-wire  214  and the lower coupling device  242  may be removed, as shown in  FIG.  23    ( FIG.  35 B ,  532 ), followed by the dilator  202 , as shown in  FIG.  24    ( FIG.  35 B ,  534 ). 
     After removal of the K-wire  214 , the lower coupling device  242 , and the dilator  202 , a lateral retraction assembly  370 , which, in this embodiment, may include the handle  310 , the lateral actuation gearbox  308 , the opposing passive lateral arms  344 , and the opposing lateral drive arms  354 , may be employed to separate or laterally retract the blade subassemblies  240  from a closed position  390 , shown in  FIGS.  25 - 27   , to a retracted position  392 , shown in  FIGS.  28 - 31    ( FIG.  35 B ,  524 ,  536 ). 
     In further detail,  FIG.  25    illustrates a perspective view of the lateral retraction assembly  370  having an open housing  342  of the lateral actuation gearbox  308  to detail one embodiment of the mechanics of the gearbox  308 . In this embodiment, the handle  310  may incorporate a worm gear  372  at its distal end. The worm gear  372  may be positioned between and enmeshed with two opposing lateral gears  374 , one bordering either side of the worm gear  372 . Each of the lateral gears  374  may include a pivot point  375  about which the remaining components of the gear  374  rotate, a teeth portion  376  that engages with the worm gear  374 , and a drive portion  378  containing a protrusion  362  configured to frictionally fit within the receiver  360  of the second end  358  of one of the lateral drive arms  354 . 
     The teeth portion  376  of each of the lateral gears  374  may have a variable radius that extends between the pivot point  375  and the teeth portion  376 . The variable radius may increase from a first radius, r 1 , located at a first end  380  of the teeth portion  376  to a larger second radius, r 2 , located at a second end  382  of the teeth portion  376 . 
     In actuating the lateral retraction assembly  370  ( FIG.  35 B ,  536 ), rotation of the worm gear  372  via the handle  342  causes the enmeshed teeth portions  376  of the opposing lateral gears  374  to travel from the first ends  380  engaged with the worm gear  372  at the smaller radius, r 1 , to the second ends  382  engaged with the worm gear  372  at the larger radius, r 2 . This travel causes the lateral gears  374  to pivot about the pivot points  375 , such that the drive portions  378  of the gears swing outward in the direction of arrow B as the radius of each lateral gear  374  increases from r1 to r 2 . This outward trajectory, in turn, drives the lateral drive arms  354 , and thus the connected blade subassemblies  240 , in the outward direction of arrow B, from the closed position  390  of  FIGS.  25 - 27    to the retracted position  392  of  FIGS.  28 - 31   . 
     Before, after, or at increments during the process of actuating the lateral retraction assembly  270  ( FIG.  35 B ,  536 ), and as discussed above in relation to  FIGS.  11 - 13   , the wing actuation assembly  290  of each blade subassembly  240  may be employed to adjust the adjustable wings  252  from the open position  280  parallel with the blades  244 , shown in  FIGS.  25 - 27   , the closed position  282  perpendicular to the blades  244 , shown in  FIG.  30   , and any position therebetween, such as the angled position (e.g., 27 degrees relative the blade  244 ), shown in  FIGS.  28 - 29  and  31    ( FIG.  35 B ,  538 ). In this regard, the two opposing blades  244  are sufficient for lateral retraction, without the need for additional blades as required by existing retractor systems, as the adjustable wings  252  prevent creep of the muscle between the blades  244  and into the surgical pathway  114  during retraction. Throughout the steps of rotating the dual-blade assembly  230  from the insertion orientation  239  to the rotated orientation  306  ( FIG.  35 B ,  516 ), laterally retracting the blade subassemblies  240  from the closed position  390  to the retracted position  392  ( FIG.  35 B ,  524 ), and adjusting the adjustable wings  252  between the open position  280  and the closed position  282  ( FIG.  35 B ,  538 ), the active monitoring tips  256  and  283  of the blades  244  and the wings  252 , respectively, may be used to provide real-time neuromonitoring to prevent impingement and/or encroachment upon adjacent nerve structures ( FIG.  35 B ,  542 ). 
       FIG.  32    illustrates a perspective view of a fully assembled lateral retractor system  200 , including all of the components, assemblies, and subassemblies discussed above. In addition and in this embodiment, the housing  342  of the lateral actuation gearbox  308  may incorporate a level  384  to assist in positioning components of the system  200  when carrying out the disclosed method  500  of creating a surgical pathway  114  using embodiments the lateral retractor system  200 , as provided in  FIG.  35   . The level  384  may be calibrated to level the system with respect to the floor, the surgical table  233 , or any appropriate reference plane. Relying on the level  384  for partial positioning reduces the amount of real-time x-ray technology (e.g., fluoroscopy) required to locate the system  200  during operation, resulting in less radiation exposure to the patient, the surgeon, and everyone else in the operating theater. In one embodiment, the level  384  may be a bubble or spirit level, or the level may be a gyroscope. 
     Once the lateral retraction assembly  270  has been employed to retract the blade subassemblies  240  to form the surgical pathway  114 , the surgeon may access the spine  100  ( FIG.  35 B ,  540 ) via the resulting surgical pathway  114 , leveraging the LED lights  254  illuminating the surgical area  266  as desired, as shown in  FIG.  33   , and observing the images transmitted from the surgical area  266  via the video output  278  from the video cameras  276 , as shown in  FIG.  34   . 
     Each of the components that form embodiments of lateral retractor system  200  discussed above may be formed of any appropriate conductive or nonconductive, autoclavable or otherwise sterilizable metal or plastic using any appropriate manufacturing method. As discussed, some components may be disposable to improve efficiency and customizability and reduce the possibility of disease transmission, while others may be reusable and sterilizable. 
     Embodiments of the lateral retractor system  200  provide three separate kinds of movement - rotation of the single-component dilator  202  and the dual-blade assembly  230  from the insertion orientation  239  to the final rotated orientation  306 , rotation of the adjustable wings  252  from the open position  280  to the closed position  282 , and retraction of the blade subassemblies  240  from the closed position  390  to the retracted position  392  - that allow for a more sophisticated initial placement of the single-component dilator  202  and the dual-blade assembly  230  in a manner parallel to the psoas muscle  102  and, therefore, less damaging to the muscle and nerve structures adjacent to the patient’s spine. Rather than crushing or trapping sensitive body tissues beneath the dilator and/or the blade assembly, the disclosed lateral retractor system enables embodiments of the dilator  102  and the dual-blade assembly  230  to bypass those tissues and instead “separate” them to create the surgical pathway  114 , as desired, with the use of an elegant design that features only two blades. In addition, rotation of the flat, narrow dilator  202  allows the dilator  202  to separate the psoas muscle tissues without the need for a more complicated series of progressively larger circular dilators, as required in the prior art. 
     Further, built-in lighting and video capabilities provide the surgeon with streamlined and flexible lighting of the surgical area and the ability to view his or her actions without hunching over the patient and/or the surgical apparatus. Detachable and disposable distal blade portions and adjustable wings allow the system to accommodate any patient physiology and can be selected in the operating theater as deemed necessary by the surgeon. In sum, the unique lateral retractor system allows for a lateral approach to the spine to be made in a more safe and efficient manner for the patient and for the surgeon. 
     In addition, continuous, real-time neuromonitoring via the active neuromonitoring tips  222 ,  256 , and  283  located at the distal ends of the dilator  102 , the blades  244 , and the adjustable wings  252 , respectively, further assists in reducing damage to the patient’s nerves and plexus in that the system may continuously monitor, and avoid, impingement or encroachment upon nerve structures within a 360-degree monitoring range about the circumference of the system  200 . This continuous neuromonitoring occurs throughout the process of forming the surgical pathway  114  and any subsequent surgical procedure. 
     In one embodiment shown in  FIGS.  36 A- 36 B , a dilator  202   a  may be substituted for the dilator  202 , discussed above, to provide neuromonitoring capabilities free of internal wires. In this embodiment, the dilator  202   a  may be formed of a conductive material such as, for example, aluminum and may leverage the internal conductivity of the dilator’s rectangular body  204   a  to form a conductive electrical pathway  205  between one or more conductive input surfaces  207  formed at a proximal end  206   a  of the rectangular body  204   a  and a conductive active monitoring tip  222   a  disposed at a distal end  208   a  of the rectangular body  204   a . 
     In this embodiment, the electrical pathway  205  may be configured via selective shielding applied to portions of the dilator  202   a . For instance, dilator surfaces intended to be nonconductive, insulated surfaces may be coated with an insulative or nonconductive layer. In one embodiment, a portion of an outer surface  211  of the aluminum body  204   a  may be coated with an anodized layer  213 , which may be nonconductive and also provide a hardened surface that resists scratching and other damage to the dilator  202   a . In one embodiment, a non-stick material such as Teflon may be added to the anodization to render the anodized layer  213  “slippery” such that the dilator  202   a  more easily glides relative to other system components and/or bodily tissues during the insertion and removal processes. 
     In applying the anodized layer  213 , portions of the outer surface  211  that are desired to be free of anodization, and thus conductive, may be masked during the anodizing process. In this embodiment, the conductive input surfaces  207  and the active monitoring tip  222   a  may be masked such that those surfaces remain conductive in their entireties. Thus, when an electrical signal is applied, through the monitoring cable  224  ( FIG.  8   ) or otherwise, to the dilator  202   a  at the conductive input surfaces  207  at the proximal end  206   a  of the dilator  202   a , the signal travels via the conductive electrical pathway(s)  205  to the active monitoring tip  222   a , which spans 360 degrees of the distal end  208   a  of the dilator  222   a . 
     Impingement or encroachment of the active monitoring tip  222   a  upon one or more nerve structures causes the nerve structures to fire and generate a responsive signal, which is conducted back through the electrical pathway(s)  205  to the monitoring cable(s)  224  in communication with the electrical pathway(s)  205  at the conductive input surfaces  207 , thereby translating the neurosensing stimulation of the active monitoring tip  222   a  to external monitoring equipment (not shown) via the monitoring cable  224  and determining, in real time, with  360  degrees of monitoring range, and with an internal-wire-free mechanism that is more simply and cost-effectively manufactured, a possibility of nerve or plexus injury as the dilator  202   a  is inserted ( FIG.  35 A ,  508 ). 
     In a manner similar to the dilator, the blades and the adjustable wings may also be configured for continuous, real-time, 360-degree neuromonitoring that does not require a wired electrical pathway within their components.  FIGS.  37 A- 37 F  illustrate front, rear, and numerous partial views of an exemplary embodiment of a blade  244   a , hingedly bordered by two opposing adjustable wings  252   a . In operation and in one embodiment, the blade  244   a  and the wings  252   a  may be electively substituted for the blade  244  and the wings  252  described above. In this embodiment, the blade  244   a  and the wings  252   a  are similar to the blade  244  and the wings  252 , discussed above, in both structure and function, and additionally feature no-wire neuromonitoring capabilities similar to the dilator  202   a , discussed above in relation to  FIGS.  36 A- 36 B . 
     In further detail and as shown in  FIGS.  37 A- 37 B , the blade  244   a  may have a proximal blade portion  246   a , a detachable, disposable distal blade portion  248   a , and opposing longitudinal edges  250   a  that extend between a proximal end  260   a  of the proximal blade portion  246   a  and a distal end  255   a  of the distal blade portion  248   a . The opposing adjustable wings  252   a  may be hingedly coupled with each of the opposing longitudinal edges  250   a  via a plurality of hinge pins  249 , as shown in  FIGS.  37 A- 37 B . 
     In this embodiment, all components forming the blade  244   a  and the adjustable wings  252   a , including the proximal blade portion  246   a , the removeable and disposable distal blade portion  248   a , the wings  252   a , and the hinge pins  249 , may be formed of a conductive material such as, for example, aluminum and may be strategically coated with a nonconductive, insulated layer such as an anodized layer  271  so as to form an internal conductive electrical pathway  253  through the multiple components. In this regard, the proximal portion  246   a  of the blade  244   a  may include at least one conductive electrical connection point, conductive input surface, or “jack”  251 , shown in  FIGS.  37 C- 37 D , and the distal portion  248   a  of the blade  244   a  and the opposing adjustable wings  252   a  may each terminate distally in respective active monitoring tips  256   a ,  283   a  similar to the active monitoring tip  222   a  of the dilator  202   a . As shown in  FIGS.  37 E- 37 F , select surfaces of the proximal blade portion  246   a  and the distal blade portion  248   a  may be masked so as to form adjacent and contacting electrically conductive surfaces  257 ,  259  when the proximal and distal blade portions  246   a ,  246   b  are assembled together. 
     In operation, the electrical connection point  251  may act as an input point where electrical conduction initiates, via the monitoring cable  224  or another appropriate source, such that an applied electrical signal conducts from the electrical connection point  251 , through the proximal blade portion  246   a , to and through the wings  252   a  via the pins  249 , to and through the distal blade portion  248   a  via the conductive surfaces  257 ,  259 , and through the active monitoring tips  256   a ,  283   a  along the conductive electrical pathway  253  shown in  FIG.  37 B . This stimulus of the active monitoring tips  256   a ,  283   a  causes nearby nerve structures to fire and generate a responsive electrical signal, which may in turn be conducted back from the active monitoring tips  256   a ,  283   a  to the electrical connection point  251  and to the monitoring cable  224  in electronic communication with external monitoring equipment, thereby sensing the stimulation of the active monitoring tips  256   a ,  283   a  caused by proximity to nearby nerve structure(s) in real time and with 360 degrees of monitoring range or field of view about an entirety of the distal ends of the blade  244   a  and the wings  252   a . Thus, via the active monitoring tips  256   a ,  283   a  of each of the distal blade portions  248   a  of the blades  244   a , continuous real-time neuromonitoring may be performed to prevent nerve or plexus injury when the blade assembly  230  is inserted over the dilator  202   a  ( FIG.  35 A ,  512 ,  514 ), as well as when the blade assembly  230  is rotated ( FIG.  35 A ,  516 ) and/or laterally separated or retracted ( FIG.  35 A ,  524 ), as discussed above. Unlike existing systems, neuromonitoring over a full 360-degree monitoring range may continue throughout the procedure. 
     Due to the multi-component nature of the wings as assembled to the blade, the internal conductive electrical pathway  253  avoids the complexity of a design which routes a wired pathway to the active monitoring tips  256   a ,  283   a , allowing for a more streamlined instrument with fewer components that is more efficient and less expensive to manufacture. 
     Although the above embodiments have been described in language that is specific to certain structures, elements, compositions, and methodological steps, it is to be understood that the technology defined in the appended claims is not necessarily limited to the specific structures, elements, compositions and/or steps described. Rather, the specific aspects and steps are described as forms of implementing the claimed technology. Since many embodiments of the technology can be practiced without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.