Patent Publication Number: US-9833226-B2

Title: Endoscopic ports for minimally invasive surgical access and methods of use thereof

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a divisional of U.S. application Ser. No. 13/878,169, filed Apr. 5, 2013, which is the U.S. National Stage of International Application No. PCT/US2011/054957, filed Oct. 5, 2011, which was published in English under PCT Article 21(2), which in turn claims the benefit of priority of U.S. Provisional Application No. 61/389,928, filed Oct. 5, 2010; each of these applications is specifically incorporated by reference herein in its entirety. 
    
    
     FIELD 
     The present disclosure relates to endoscopic ports and method for using the same in connection with various surgical procedures. 
     BACKGROUND 
     Various conditions, illness, and/or injuries that affect the brain require surgical procedures to provide access to the brain in order to treat the affected area. For example, many brain tumors are life-threatening and require a surgical procedure to access and remove at least a portion of the tumor. For primary brain tumors, an attempt at maximal surgical resection is often the preferred treatment, usually followed by adjuvant chemotherapy and radiation therapy. For brain metastases, resection is often recommended for large, symptomatic metastases as well as for single metastases in patients with otherwise high functional status. Appropriate tumor removal facilitates neurologic recovery, functional recovery, and sometimes survival. 
     However, safely providing access to such treatment areas can be challenging. For example, the vast majority of intraparenchymal brain tumors are surrounded by a “cuff” of overlying brain cortex as well as subcortical white matter, which in turn, surrounds the actual tumor. Much of the morbidity and risk inherent to brain tumor surgery is related to the manipulation and dissection of this tissue. In addition, the amount of dissection of overlying brain increases with increasing lesional depth. As a result, the risk of neurological injury and surgical complications can be even greater for deep-seated brain tumors. 
     SUMMARY 
     In a first embodiment, an endoscopic port apparatus is provided. The apparatus includes an inflatable member, a rigid tube member, a housing, and an actuator. The inflatable member has a proximal portion and a distal portion. At least the distal portion of the inflatable tube member is inflatable between a collapsed state and an expanded state. The housing has an interior space configured to receive the rigid tube member. The actuator is configured to exert a force on the rigid tube member to cause it to move from the interior space in the housing into the distal portion of the inflatable member when the inflatable member is in the expanded state. 
     In some embodiments, a guide member extends into the inflatable member to increase the rigidity of the inflatable member. The guide member can be coupled to a distal end of the inflatable member to facilitate removal of the distal end of the inflatable member to establish a distal opening in the rigid tube member. In other embodiments, the actuator comprises a plunger, a motorized linear actuator, and/or a magnetic member that is coupled to the rigid tube to exert a force on the rigid tube member to push the rigid tube member into the distal portion of the inflatable member. The rigid tube member can be substantially transparent to improve visibility in the vicinity of the endoscopic port apparatus. In some embodiments, the transparent tube is clear. 
     In some embodiments, the housing and proximal portion of the inflatable member are maintained in a substantially airtight manner. The proximal portion of the inflatable member can extend into the housing. For example, when the rigid tube member is received in the housing, the rigid tube member is received at least partly within the proximal portion of the inflatable member. In other embodiments, the proximal portion of the inflatable member is coupled to a distal end of the housing, such that when the rigid tube member is received in the housing the rigid tube member does not substantially overlap with the inflatable member. 
     In another embodiment, a method for providing an endoscopic port is provided. The method includes inserting a distal portion of an expandable member into soft tissue in a patient&#39;s body and inflating the distal portion of the expandable member to form a passageway in the soft tissue. A rigid tube member is delivered into the passageway formed by the expandable member. The rigid tube member is delivered inside the inflated distal portion of the inflatable member and a port is established between a proximal opening in the rigid tube member and a distal opening in the rigid tube member. 
     In some embodiments, establishing the port comprises cutting a distal end of the expandable member and removing the cut distal end from within the rigid tube member. In other embodiments, the insertion of the distal portion of the expandable member comprises inserting a guide member into the distal portion and directing the guide member and distal portion of the expandable member through the soft tissue. The guide member can be coupled to the distal end of the expandable member and the removal of the cut distal end can include removing the guide member from within the rigid tube member. In other embodiments, establishing the port further comprises cutting the expandable member around the proximal opening of the rigid tube member. 
     In some embodiments, the rigid tube member can be positioned within a housing and the rigid tube member can be delivered into the passageway by exerting a force on the rigid tube member to push it into the inflated distal portion of the inflatable member. In other embodiments, a proximal portion of the inflatable member can extend into the housing and the rigid tube member is positioned inside the proximal portion of the inflation member before being delivered into the passageway. The exertion of the force on the rigid tube member to push it into the inflated distal portion of the inflatable member can be achieved by manually depressing a plunger, activating a motorized linear actuator, and/or magnetically coupling the rigid tube member with an external magnet. 
     In some embodiments, the method further comprises inserting a second expandable member into the rigid tube member, at least partially inflating the second expandable member within the endoscopic port, removing the rigid tube member from the passageway, and deflating the expandable member to reduce the speed at which the soft tissue surrounding the passageway expands to fill the passageway upon removal of the rigid tube member. 
     In another embodiment, a method for providing an endoscopic port includes inserting a distal portion of an expandable member into soft tissue in a patient&#39;s body, inflating the distal portion of the expandable member to form a passageway in the soft tissue, delivering a rigid tube member into the passageway formed by the expandable member, and removing the expandable member to establish a port between a proximal opening in the rigid tube member and a distal opening in the rigid tube member. The rigid tube member is delivered along an outside surface of the inflated distal portion of the inflatable member. 
     In yet another embodiment, a method for removing an endoscopic port includes inserting an expandable member into a passageway formed by an endoscopic port, at least partially inflating the second expandable member within the endoscopic port, removing the rigid tube member from the passageway, and deflating the expandable member to reduce the speed at which the soft tissue surrounding the passageway expands to fill the passageway upon removal of the rigid tube member. 
     The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  illustrate an embodiment in which an expandable member is delivered into soft tissue of a patient and expanded to form a passageway. 
         FIGS. 2A-2C  illustrate an embodiment in which an endoscopic port is formed by inserting a rigid tube into a passageway in a patient. 
         FIGS. 3A-3H  illustrate an embodiment in which an endoscopic port is formed by inserting a rigid tube into a passageway in a patient. 
         FIGS. 4A-4C  illustrate an embodiment for reducing trauma to a patient during removal of an endoscopic port. 
         FIGS. 5A-5C  illustrate additional steps in the embodiment shown in  FIGS. 4A-4C . 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments of endoscopic port technology and their methods of use are disclosed herein. The following description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Various changes to the described embodiments may be made in the function and arrangement of the elements described herein without departing from the scope of the invention. 
     As used in this application and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the term “coupled” generally means electrically, electromagnetically, and/or physically (e.g., mechanically or chemically) coupled or linked and does not exclude the presence of intermediate elements between the coupled or associated items absent specific contrary language. 
     Although the operations of exemplary embodiments of the disclosed method may be described in a particular, sequential order for convenient presentation, it should be understood that disclosed embodiments can encompass an order of operations other than the particular, sequential order disclosed. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment, and may be applied to any embodiment disclosed. 
       FIGS. 1A-1C  illustrate an embodiment of an endoscopic port apparatus and a method of using the same.  FIG. 1A  illustrates an inflatable member  100  that is inflatable from a collapsed state ( FIG. 1A ) to an expanded state ( FIG. 1C ). As shown in  FIG. 1B , when inflatable member  100  is in the collapsed state, it has a relatively low profile that permits a distal end  108  of inflatable member  100  to be maneuvered through a portion of the brain  102  (or other soft tissue of the patient) until it reaches to a location of interest. Thus, for example, distal end  108  of inflatable member  100  can be delivered through the cortex and white matter of the brain  102  in a direction that is indicated by arrow  106  ( FIG. 1B ). Once distal end  108  of inflation member  100  reaches the desired location (e.g., at or adjacent to the location of a lesion  104 ), inflation member  100  can be inflated to the expanded state as shown in  FIG. 1C . The delivery of inflation member  100  to the desired location in the body can be facilitated by various imaging techniques such as magnetic resonance imaging (MRI) and/or non-imaging techniques such as frame-based or frameless stereotactic guiding systems. 
     Inflatable member  100  can comprise a tubular balloon catheter made of non-compliant or semi-compliant material. In some embodiments, inflatable member  100 , or portions thereof, can be substantially transparent allowing for visualization through inflatable member  100 . The term “transparent” as used herein refers to the ability see through the tube member or other transparent structure. Transparent elements, therefore, include “clear” elements, which provide substantially unimpeded views through the element. 
     When inflated, inflatable member  100  forms a longitudinally extending lumen that is large enough to permit passage of other instruments, as described below. The material of the expandable portion of inflation member  100  is desirably selected so that it has sufficient structural integrity to achieve inflation pressures suitable for dilating the brain tissue in the manners disclosed herein. To provide additional rigidity to inflatable member  100  and/or to facilitate the maneuvering of inflatable member to the desired location, a guide member  110  can extend through inflation member  100  as shown in  FIGS. 1A-1C . 
     In some embodiments, guide member  110  can extend through inflation member  100  so that a distal end of guide member  110  is adjacent distal end  108  while distal end  108  is being delivered into the body of the patient. Also, if desired, a proximal end (not shown) of guide member can extend beyond the proximal end of inflation member  100  for manipulation by the surgeon to facilitate delivery of the distal end  108  of inflation member  100  to the desired location of interest within the body of the patient. 
     After distal end  108  of inflation member  100  is delivered to the desired location, an inflation device (not shown) with one or more ports in fluid connection with a fluid source (not shown) can deliver an expansion fluid (e.g., air, saline, etc.) into inflation member  100  to cause inflation member  100  to expand from the collapsed state to the expanded state. Inflation of inflatable member  100  can be performed slowly to cause the surrounding brain tissue to retract in a substantially atraumatic manner. As inflation member  100  expands, the portion of expansion member  100  within the body forms a passageway  114  ( FIG. 2A ) within the body. Passageway  114  extends from an exterior surface or area of the patient (e.g., an exterior brain surface  116 ) to the distal end  108  of inflation device  100 . 
     To maintain the opening into the body provided by passageway  114  and provide a surgeon with access to the internal area of the patient in the vicinity of the distal end  108  of inflation member  100  (e.g., lesion  104 ), a rigid tube member  112  can be delivered through the lumen of the expanded inflation member  100  and into passageway  114 . Rigid tube member  112  is desirably a generally transparent tube that allows the surgeon to visualize the anatomy surrounding rigid tube member  112 . 
       FIGS. 2A-2C  illustrate the delivery of rigid tube member  112  from a first position that is outside of the body of the patient to a second position that is at least partially within the body of the patient to establish a port between openings at the two opposing ends of rigid tube member  112 . In the first position, rigid tube member  112  is positioned within inflatable member  100  at a location external to the body of the patient. Rigid tube member  112  can be pre-loaded or pre-installed in the proximal portion of inflatable member  100  before the inflatable member  100  member is introduced into the patient (see, e.g.,  FIG. 3B ). After inflatable member  100  is expanded (e.g.,  FIG. 1C ), rigid tube member  112  is moved in the direction of arrow  118  into passageway  114  as shown in  FIG. 2A . 
       FIG. 2A  illustrates rigid tube member  112  partially delivered to a desired location within the body and  FIG. 2B  illustrates rigid tube member  112  fully delivered to a desired location within the body. In some embodiments, when rigid tube member  112  is fully delivered (e.g.,  FIG. 2B ), rigid tube member  112  extends substantially through passageway  114 . A portion of rigid tube member  112  (e.g., proximal portion  120 ) can extend beyond passageway  114  and out of the body of the patient. 
     After rigid tube member  112  is fully delivered, the fluid pressure inside inflatable member  100  can be reduced. As the fluid pressure in the tubular balloon is reduced, inflatable member  100  is at least partially collapsed so that an inside diameter of inflation member  100  is reduced. When the portion of inflation member  100  that surrounds rigid tube member  112  reduces in diameter a sufficient amount, an inside surface of inflation member  100  will contact an outside surface of rigid tube member  112  and effectively form a double-walled rigid tube. The material of the expandable portion of the inflation member  100  can be selected so that the material exhibits an amount of elasticity (e.g., stretch) that is adequate to provide a sufficient amount of frictional adhesion between the inside surface of the tubular balloon and the outside surface of rigid tube member  112  to effectively form a single piece double-walled tube when the fluid pressure within inflation member  100  is released. 
     Once rigid tube member  112  is in the desired position and the fluid pressure within inflation member  100  is released to form a double-walled tube, a port can be established between the two openings of rigid tube member  112  by removing portions of inflatable member  100 . For example, the distal end  108  of inflatable member  100  can be removed to provide access to a distal opening  122  of rigid tube member  112 . 
     The distal end  108  of inflatable member  100  can be separated at the distal opening  122  of the rigid tube via sharp dissection and the separated distal end  108  can be removed from the rigid tube. For example, as shown in  FIG. 2B , the distal end  108  of inflatable member  100  can be cut using a tool, such as a pair of rotatable scissors  124  with an external handle member  126 . The cutting portion  130  of the rotatable scissors  124  can be positioned at the end of a shaft  128  that is long enough to extend through rigid tube member  112  to reach the distal end  108  of inflatable member  100 . As shown in  FIG. 2C , after distal end  108  is cut by the cutting portion  130  of rotatable scissors  124 , the cut distal end  108  can be removed through the inside of rigid tube member  112 . Cut distal end  108  can be removed by any means sufficient to capture and pull the cut distal end  108  out of rigid tube member  112  in the direction indicated by arrow  132 . 
     In one embodiment, guide member  110  can be coupled to the distal end  108  of inflatable member  100  such that after the distal end  108  is cut, the cut distal end  108  can be removed by simply pulling guide member  110  out of rigid tube member  112 . Accordingly, in this embodiment, guide member  110  can facilitate delivery of the distal end  108  to the desired location and facilitate removal of the distal end  108  after the rigid tube member  112  is positioned within passageway  114 . 
     After removal of the distal end  108  lesion  104  is generally accessible through the distal opening  122  of rigid tube member  112 . If desired, inflatable member  100  can also be cut in the area of a proximal opening  134  of rigid tube member  112  (see, e.g.,  FIG. 2C ) to provide access through rigid tube member  112  at the proximal opening  134 . Cutting or removing inflatable member  100  in the area of the proximal opening  134  can be performed in various ways. If a proximal end of the rigid tube member  112  extends out of the body as shown in  FIG. 2C , the area of inflatable member  100  around the proximal opening  134  can be easily accessed for cutting, separating, and/or removing the portion of inflatable member  100  that extends proximally from proximal opening  134  in rigid tube member  112 . After removal of the distal end  108  and a proximal portion of inflatable member  100 , the double-walled endoscopic port formed by rigid tube member  112  and the portion of inflatable member surrounding rigid tube member  112  establishes access into the body through the proximal and distal openings  134 ,  122 . 
     In other embodiments, a portion of rigid tube member  112  can be removed along with a portion of the proximal end of inflatable member  100 . In this manner, the inflatable member  100  and rigid tube member  112  can be cut at any length outside of the body and the distance that rigid tube member  112  extends outside the body can be adjusted by the surgeon in accordance with the surgeon&#39;s preferences. 
     Alternatively, access to the proximal opening  134  can be provided through a proximal end of the inflatable member  100  (not shown). Thus, the rigid tube member  112  can provide a double-walled endoscopic port through which lesion  104  is exposed for resection or other treatment. If desired, one or more clamping or locating mechanisms can be attached to rigid tube member  112  in the vicinity of the proximal opening  134  to secure the rigid tube member  112  in a desired orientation. 
     Various mechanisms can be used for introducing the rigid tube member  112  into the passageway  114  defined by the expanded inflatable member  100 . Referring to  FIGS. 3A-3H , a step-by-step process for introducing a rigid tube member  112  using a housing  136  is described. 
       FIG. 3A  illustrates rigid tube member  112 .  FIG. 3B  illustrates rigid tube member  112  pre-installed within inflatable member  100  in its non-inflated, collapsed state, thereby providing a reduced diameter collapsed portion  138  of inflatable member  100  and an enlarged diameter portion  140  that contains rigid tube member  112 . When the collapsed portion  138  is expanded, the enlarged diameter portion  140  can also be at least partially inflated since it is in fluid communication with the collapsed portion  138 . 
       FIG. 3C  illustrates housing  136 , which is configured to be held by the surgeon to facilitate insertion of collapsed portion  138  of inflatable member  100  into the body of the patient (e.g., into the soft tissue of the brain as shown in  FIG. 1B ). Housing  136  can comprise a handle with an interior area or space  139  for receiving the enlarged diameter portion  140  and rigid tube member  112 . 
     The enlarged diameter portion  140  can have a larger diameter than the collapsed portion  138  in the absence of any expansion forces. In the embodiment illustrated in  FIG. 3B , the enlarged diameter portion  140  of inflatable member  100  is constructed so that its inner diameter is slightly larger than the outer diameter of rigid tube member  112 . Thus, inflatable member  100 , in its collapsed state, has a diameter that varies along its length, with the portion that is contained within the housing  136  having a larger diameter than the portion outside of the housing  136 . As shown in  FIG. 3C , enlarged diameter portion  140  can substantially fill a cavity (e.g., interior space  139 ) inside housing  136  and rigid tube member  112  can be positioned inside of the enlarged diameter portion  140  of inflatable member  100 . Also, if desired, inflatable member  100  and housing  136  can be coupled together so that movement of housing  136  by the surgeon causes relative movement in the collapsed portion  138  of inflatable member  100 . 
     In an alternative embodiment, the enlarged diameter portion  140  can be expanded (stretched) to its enlarged diameter by the force exerted on it by an outer surface of rigid tube member  112  when rigid tube member  112  is inserted into the enlarged diameter portion  140 . To position rigid tube member  112  inside the enlarged diameter portion  140 , inflatable member  100  can be fully inflated and rigid tube member  112  can be moved inside the inflated, enlarged diameter portion  140 . When the pressure inside inflatable member  100  is released, the enlarged diameter portion  140  can collapse until an internal surface of the enlarged diameter portion  140  fits tightly against the external surface of rigid tube member  112 . Thus, the rigid tube member  112  can be positioned inside the enlarged diameter portion  140  so that the enlarged diameter portion  140  is in a stretched, but not inflated, state after it receives rigid tube member  112 . 
     Collapsed portion  138  is desirably formed with a plurality of longitudinal folds to achieve a small diameter profile that is capable of expanding to the desired expansion diameter. During inflation, the plurality of longitudinal folds of the collapsed portion  138  unfold until the partially inflated collapsed portion  138  reaches its net inner diameter. In some embodiments, the net inner diameter is slightly less than the outer diameter of rigid tube member  112 . The partially inflated collapsed portion  138  can then be further inflated until reaches a pressure that stretches the collapsed portion  138  to an inner diameter that is slightly larger than the outer diameter of rigid tube member  112 . 
       FIG. 3D  illustrates inflatable member  100  in an inflated state. In the inflated state, the collapsed portion  138  shown in  FIG. 3C  has been inflated to provide an expanded portion  142  that defines a passageway in the body of the patient (e.g.,  FIG. 1C ).  FIGS. 3E and 3F  illustrate rigid tube member  112  being moved downward (e.g., distally with reference to a patient) into the expanded portion  142  to establish a port in a passageway defined by the expanded portion  142 . After rigid tube member  112  is delivered to the desired location within the expanded portion  142 , the fluid pressure in inflatable member  100  can be reduced, allowing the expanded portion  142  to be reduced until an inside surface of the inflatable member  100  contacts the outside surface of rigid tube member  112  as described elsewhere herein. 
     Referring now to  FIGS. 3G and 3H , after rigid tube member  112  is in the desired position, the proximal opening  134  and distal opening  122  of rigid tube member  112  can be exposed by cutting, separating, and/or removing portions of inflatable member  100  that are in vicinity of the proximal opening  134  and the distal opening  122 . Thus, for example, distal end  108  of inflatable member  100  can be removed (see, e.g.,  FIGS. 2B and 2C ) along with portions of inflatable member  100  that are proximal to the proximal opening  134  of rigid tube member  112 . 
     In another embodiment, instead of extending into and/or through the housing, a proximal open end of inflatable member  100  can be coupled to a distal end  144  of housing  136  in an substantially airtight fashion. Thus, everything inside housing  136  can be under the same pressure as inflatable member  100 . As in the other embodiments, the housing  136  can have an interior space for receiving rigid tube member  112  inside housing  136 ; however, in this embodiment, when rigid tube member  112  is in housing  136 , rigid tube member  112  does not substantially overlap with the proximal end of inflatable member  100 . Instead, rigid tube member  112  is not inserted into inflatable member  100  until the collapsed portion  138  is inflated to form the expanded portion  142 . Then, the rigid tube member  112  is expelled from housing  136  and directed into the proximal open end of inflatable member  100 . 
     Various mechanisms can be provided for delivering rigid tube member  112  into the passageway defined by the expanded portion  142  of inflatable member  100 . Such mechanisms can include both manually-operated mechanisms that provide direct tactile feedback to the surgeon and non-manual mechanisms that are motor-driven or otherwise powered. For example, an actuator  145  can be provided for moving rigid tube member  112  as described herein. Actuator  145  can comprise, for example, a lever or plunger that manually pushes the rigid tube member into the passageway defined by inflatable member  100 . The lever or plunger can also be at least partially inside inflatable member  100  to facilitate the pushing of rigid tube member  112  through the inside of inflatable member  100 . Alternatively, the lever or plunger can be positioned outside the inflatable member and can exert a force on the rigid tube member through inflatable member  100 .  FIGS. 3E and 3F  show an actuator  145  that is a plunger-type mechanism that moves between a first non-deployed position ( FIG. 3E ) and a second deployed position ( FIG. 3F ) to move the rigid tube member  112  into the inflated collapsed portion  138 . 
     As shown in  FIGS. 3B-3F , a pressure gland  147  can be included on housing  136  to maintain pressure within housing  136  during deployment of actuator  145 . In the embodiment shown in  FIGS. 3B-3F , actuator  145  comprises a pushrod that is inserted through pressure gland  147  and into the proximal end of housing  136 . Movement of the pushrod towards rigid tube member  112  causes a distal end of the pushrod to pierce the enlarged diameter portion  140  of inflatable member  100  and push the rigid tube member  112  downward into the inflated collapsed portion  138 . Because inflatable member  100  is sealed to the hollow housing  136  at both ends (i.e., the proximal and distal end of housing  136 ), pressure can be maintained in the housing  136  as the push rod is inserted through pressure gland  147  and contacts rigid tube member  112 . 
     In other embodiments, a motorized linear actuator can be provided to exert a force on rigid tube member  112  to cause it to move into the expanded portion  142  of inflatable member  100 . In another embodiment, a magnet and a corresponding responsive material on or adjacent the rigid tube member  112  can be provided to push the rigid tube member  112  downward (e.g., distally) without requiring penetration and/or direct contact with inflatable member  100 . 
     By delivering rigid tube member  112  through the inside of inflatable member  100  in the manners described herein, rigid tube member  112  does not directly contact the tissue surrounding inflatable member  100  during delivery of rigid tube member  112  from a position outside the body to a position at least partially inside of the body. Accordingly, the shear drag on the brain tissue caused by direct contact with rigid tube member  112  can be eliminated and/or greatly reduced in comparison to conventional methods that require directly contacting brain tissue during insertion of an endoscopic port. Moreover, the reduced diameter of the collapsed portion  142  only requires a very small channel for delivery of the inflatable member  100  through the cortex and white matter prior to dilatation of the inflatable member  100 . In some embodiments, the diameter of the collapsed portion can be less than about 4 mm, less than about 3 mm, or even less than about 2 mm. Such reduced diameter delivery channels can facilitate deeper access while being less traumatic to the tissue surrounding the delivery channel than existing methods. 
     In some embodiments, rigid tube member  112  can be non-cylindrical. For example, rigid tube member  112  can be oval in cross section or shaped in another useful shape. Desirably, such shapes would not have sharp edges that could cause trauma to surrounding tissue. If desired, when used in combination with a non-cylindrical rigid tube member, inflatable member  100  can be also be non-cylindrical in cross section. For example, the inflatable member can be of the same general cross-sectional shape as the rigid tube member to facilitate delivery of the non-cylindrical rigid tube member. 
     In some embodiments, rather than delivering rigid tube member  112  through the lumen of expandable member  100  (i.e., within expandable member  100 ), rigid tube member  112  can be deployed down the outer edge of inflatable member  100  (i.e., so an inner surface of rigid tube member  112  is in contact with an outer surface of inflatable member  100 ). If rigid tube member  112  is delivered on the outside of inflatable member  100 , inflatable member  100  can simply be withdrawn from within rigid tube member  112  to provide access through the passageway created by the expanded inflatable member  100  within the body. Thus, there is no need to cut portions of inflatable member  100  away to provide access to the proximal and/or distal openings of rigid tube member  112 . A disadvantage of this approach, however, the shear forces on the tissue surrounding inflatable member are not as greatly reduced as in the case where rigid tube member  112  is delivered inside inflatable member  100  as described herein in other embodiments. 
     After lesion  104  is removed and/or other desired treatments are performed, rigid tube member  112  can be slowly withdrawn. In some embodiments, it may be desirable to further reduce the speed in which the brain tissue contracts back into passageway  114  that was maintained opened by rigid tube member  112 .  FIGS. 4A-4C and 5A-5C  illustrate a method for further reducing the speed of contraction around passageway  114 . As shown in  FIG. 4B , a second inflatable member  150  can be inserted into rigid tube member  112  in the direction indicated by arrow  152 . Second inflatable member  150  can be inflated so that an external diameter of second inflatable member  150  is slightly less than an inner diameter of rigid tube member  112 , as shown in  FIG. 4C . 
     After inflation of second inflatable member  150 , rigid tube member  112  (and the portion of inflatable member  100  coupled therewith to form the double-walled tube) can be withdrawn with less immediate contraction of the brain tissue immediately surrounding rigid tube member  112 .  FIG. 5A  illustrates the removal of rigid tube member  112  over second inflatable member  150  by pulling rigid tube member  112  in the direction indicated by arrow  154 . After removal of rigid tube member  112 , second inflatable member  150  can then be slowly deflated, allowing the brain tissue to slowly contract into the volume recently retracted by rigid tube member  112 . When second inflatable member  150  is reduced in diameter to a desired size, such as the reduced diameter size that is shown in  FIG. 5B , second inflatable member  150  can be completely withdrawn from the body as shown in  FIG. 5C . After second inflatable member  150  is withdrawn from the body by pulling second inflatable member  150  in the direction indicated by arrow  156 , the brain tissue can be allowed to continue to contract until it fills the void left by the withdrawal of second inflatable member  150 . 
     By using the inflatable members disclosed herein, the speed of insertion, inflation, deflation, and removal can be more easily controlled by a surgeon. The systems and methods disclosed herein can be adapted to be formed in any desired size, including for example, sizes between 10 and 20 mm, thereby increasing versatility for visualization and resection purposes. Thus, the systems and methods disclosed herein can reduce trauma to healthy brain tissue, improve versatility of conduit size, and facilitate the control rate of brain tissue distortion during port introduction and/or port removal. This allows deeper and safer access for brain tumors in which surgery may not otherwise have been attempted. 
     Although the embodiments described herein are generally directed to the surgical removal of brain tumors, this technology has the potential to facilitate other surgical applications as well. For example, the dilatable ports disclosed herein can be used to deliver local therapies to deep-seated tumors and lesions (e.g. chemotherapeutic wafers, stem cells, etc.). In addition, the dilatable ports disclosed herein can be used for non-tumor surgery, such as the evacuation of intracerebral hemorrhages. Finally, the dilatable ports disclosed herein can be used in non-neurosurgical applications, such as laparoscopic surgery or thoracoscopic surgery, as a conduit through which surgical instruments could be introduced. 
     In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.