Patent Publication Number: US-8109956-B2

Title: Systems and methods for surgical removal of tissue

Description:
BACKGROUND 
     The present disclosure relates to treatment of body tissues. More particularly, it relates to surgical systems, instruments, and methods useful in reducing and/or removing tumorous tissues. 
     Removal or reduction of body tissues is performed for a variety of reasons and on many types of tissues. For example, an organ may be removed upon its failure. In some cases, a tumor and/or surrounding tumor must be eliminated. Tumors are commonly treated with chemotherapy, radiation, surgery, and other techniques. When surgery is the treatment of choice, a variety of surgical instruments, such as a cavitational ultrasonic surgical aspirator (CUSA) or a surgical laser knife, are commonly used. 
     Brain surgery is the treatment of choice for accessible brain tumors. While a CUSA may be used to treat many tissues other than brain tumors, brain surgery provides a useful example to highlight some of the difficulties arising in the surgical removal of delicate tissues. The goal of surgery is to remove as much tumor tissue as possible. Among other procedures, the most commonly performed surgery for removal of a brain tumor is a craniotomy. In general, the neurosurgeon makes an incision into the scalp, cranium, dura, meninges, and cortex to expose an area of brain over the tumor. Location and removal of the tumor then takes place. 
     The delicate tissues associated with the human brain anatomy give rise to several concerns when using a CUSA, laser knife, or other brain surgery instruments such as cold steel instruments, ultrasonic cutting devices, and bipolar radiofrequency plasma ablation systems. By way of reference, the brain is covered by three membranes or meninges that in turn are surrounded by the skull. The three layers of meninges are the dura mater (immediately beneath the skull), the arachnoid, and the pia mater. Spinal fluid flows in the space between the arachnoid and the pia mater membranes, known as the subarachnoid space. These meninges are thin and delicate, with the pia mater carrying or maintaining the many blood vessels associated with the brain. Due to the friable nature of especially the pia mater, neurosurgeons must exercise great care when attempting to surgically remove a brain tumor; unintended damage to the pia mater can diminish the primary blood supply to the brain. Unnecessary injury to other healthy structures, such as the arachnoid or brain tissue (e.g., cerebral cortex) as well as unnecessary injury to cranial nerves and arteries supplying the brain (and brain stem) also can lead to patient impairment. With this in mind, CUSA instruments deliver ultrasonic action to remove tissue and bone. The surgeon attempts to place the ultrasonic cutting tip against tissue to be destroyed. However, high frequency cutting may also occur and damage tissue surrounding the targeted tumor when touched by the instrument&#39;s shaft. Further, due to the relatively large size of the CUSA handpiece, it may be difficult to visually confirm placement of the ultrasonic shaft/tip. Similarly, use of a laser knife may give rise to unintended tissue damage due to local heat in and around the incision line. 
     In another example, when treating of tumors and/or lesions in the airway great care also must be taken with delicate tissues, such as the vocal cords or the esophagus. For instance, lesions or tumors must be removed while sparing the surrounding mucosa to avoid scarring the vocal cords. In another instance, an overly aggressive resection of tissue in the airway can lead to a fistula involving the esophagus, which in turn can lead to aspiration of food and fluid. 
     In light of the above, surgeons and others continue to face the many challenges presented during reduction or removal of tumors and/or lesions while attempting to minimize normal tissue damage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a system for surgically reducing or removing tissue in accordance with principles of the present disclosure; 
         FIG. 2  is a perspective view of a surgical instrument useful with the system of  FIG. 1 ; 
         FIG. 3A  is an exploded view of a blade assembly portion of the instrument of  FIG. 2 ; 
         FIG. 3B  is an enlarged, perspective view of a proximal region of an inner tubular member of the assembly of  FIG. 3A ; 
         FIG. 3C  is an enlarged, perspective view of a proximal region of an inner tubular member of the assembly of  FIG. 3A ; 
         FIG. 4A  is an enlarged, perspective view of a distal region of an outer tubular member of the assembly of  FIG. 3A ; 
         FIG. 4B  is an enlarged, sectional view of a distal cutting window of an inner tubular member of the assembly of  FIG. 3A . 
         FIG. 5  is a cross-sectional view of the blade assembly and blade coupler of  FIG. 3A  upon final construction; 
         FIG. 6  is a cross-sectional view of the blade assembly and blade coupler of  FIG. 3A  upon final construction; 
         FIG. 7A  is a perspective view of the blade assembly and blade coupler of  FIG. 3A  upon final construction; 
         FIG. 7B  is a cross-sectional view of a portion of the instrument upon final construction; 
         FIGS. 8A and 8B  illustrate operation of a cutting implement portion of the instrument of  FIG. 7 ; and 
         FIGS. 9A and 9B  illustrate use of the system of  FIG. 1  in surgically removing a brain tumor. 
     
    
    
     DETAILED DESCRIPTION 
     Some aspects in accordance with principles of the present disclosure relate to a surgical system and method for surgically treating a tumor or other body tissue of a patient. 
     In one aspect, the system includes a surgical cutting instrument, a motor, and a source of negative pressure. The cutting instrument includes an inner member, an outer member, a handpiece, and an aspiration control mechanism. The inner member includes a distal cutting tip, whereas the outer member has a distal region forming a cutting window and an elevator tip distal the cutting window. The handpiece maintains the inner and outer members such that the inner member is rotatably received within the outer member, with the cutting tip being exteriorly exposed at the cutting window. Further, the cutting tip and the distal region combine to define a cutting implement. The motor is connected to the inner member for moving the inner member relative to the outer member, for example as part of a cutting operation. 
     In another aspect, the system includes a fluid pathway extending from the cutting implement through the handpiece to the source of negative pressure. In some configurations, the aspiration control mechanism is incorporated within the handpiece while in other configurations, the aspiration control mechanism is incorporated within a coupler configured to couple the inner and outer members to the handpiece. The aspiration control mechanism includes a control pathway integrated within an interior of the handpiece or of the coupler to define a segment of the fluid pathway. The aspiration control pathway includes a user interface port exposed on an exterior of the handpiece or the coupler and which is open to the ambient environment. The user interface port provides user control over a level of vacuum (supplied via the remainder of the fluid pathway and the negative pressure source) applied at the cutting implement. For example, by obstructing more or less of the user interface port, the level of vacuum applied at the cutting implement is increased or decreased, respectively. With some alternative constructions in accordance with principles of the present disclosure, the system is configured such that when the source of negative pressure is generating negative pressure and the user interface port is exteriorly unobstructed, a level of vacuum applied at the cutting implement is substantially zero. 
     Using this arrangement, a variety of body tissues and/or tumors can be treated. For the sake of illustration, treatment of a brain tumor is described. First, an opening is created through a skull of the patient to provide external access to a treatment site at which the brain tumor is located. The cutting implement is delivered through the opening to the treatment site. The elevator tip is inserted partially between the target tissue (e.g., the tumor) and the surrounding tissue of the treatment site, such as one or more of dura, arachnoid, pia, and cerebral cortex. The cutting tip is placed into contact with the tumor. The inner member is then moved relative to the outer member, thereby causing the cutting tip to cut tissue of the tumor. Finally, the treatment site is selectively aspirated to remove the cut or debrided tumor tissue. By using the elevator tip to at least partially isolate the tumor and selectively aspirating the treatment site, the likelihood of damaging the surrounding normal tissue is minimized. In some alternative aspects, methods of the present disclosure further include varying a level of vacuum (or aspiration rate) at the treatment site throughout the procedure, with the tumor being drawn into contact with the cutting tip via applied aspiration prior to a cutting operation. 
     Embodiments of the system also can be employed in removing brain tumors via other access pathways. For example, access to the brain may be obtained through the nose, palate, and oropharnyx to treat tumors such as pituitary tumors, clival cordomas, cholesterol granulomas, neuroesthesioblastomas, skull base meningiomas, and meningoceles. In another example, embodiments of the system are applied to treat to tumors via the lateral skull base, such as acoustic neuromas. 
     In other embodiments, tumors and/or lesions of the upper and lower airway are treated according to principles of the present disclosure. Non-limiting examples of these types of tumors and/or lesions include those generally occurring on the vocal cords, as well as recurrent respiratory papilloma, cysts, polyps, Reinke&#39;s edema or polypoid vocal corditis, benign tumors, and malignant tumors. In another non-limiting example, embodiments of the present disclosure are applicable to treating tumors and/or lesions in the bronchus. 
     The above system is highly useful in performing tumor surgery and other types of surgery. In tumor surgery, the system affords the neurosurgeon the ability to more precisely effectuate cutting only of the brain tumor, as well as to control aspiration applied to the treatment site. 
     These aspects, and other aspects, of the present disclosure are described and illustrated in association with  FIGS. 1-9B . 
     A surgical system  20  in accordance with aspects of the present disclosure for reducing or removing body tissues is shown in  FIG. 1 . In just one example, system  20  can be used in debriding a brain tumor as part of brain surgery. The system  20  includes a surgical cutting instrument  22 , a source of negative pressure  24 , and a power source  26 . Details on the various components are provided below. In general terms, however, the surgical instrument  22  includes a blade assembly  28  forming a cutting implement  30  (referenced generally), a handpiece  32 , and an integrated aspiration control mechanism  34  (referenced generally). The source of negative pressure  24  is fluidly connected to the cutting implement  30  via a fluid pathway  36  extending up to and through a housing  38  of the handpiece  32 . In one aspect, a proximal region of the handpiece  32  also includes an aspiration passage  37  that partially defines the fluid pathway  36  and which is fluidly connected to the negative pressure source  24  via tubing  47 . Finally, the power source  26  is electrically connected to a motor (shown in  FIG. 7B  as motor  202 ) maintained by the handpiece  32 . 
     During use in surgically reducing or removing a tumor, the cutting implement  30  is deployed to a treatment site, with the user manipulating the handpiece  32  to achieve a desired position of the cutting implement  30  relative to the brain tumor. The power source  26  energizes the motor to effectuate a tumor cutting operation at the cutting implement  30 . Finally, the aspiration control mechanism  34  is manually operated by the user to selectively effectuate aspiration at the cutting implement  30  via a vacuum generated by the source of negative pressure  24 . In some configurations, the aspiration control mechanism  34  includes a user interface port  35  which affords the user the ability to vary the rate or level of aspiration, as well as an aggressiveness of cutting at the cutting implement  30 . 
     With the above general construction of the system  20  in mind, features associated with the surgical instrument  22  in accordance with aspects of the present disclosure are shown in greater detail in  FIG. 2 . The surgical instrument  22  includes the blade assembly  28 , the handpiece  32 , and the aspiration control mechanism  34  as mentioned above. 
     In some configurations, surgical instrument  22  also includes a blade coupler  33  and/or a transition assembly  42 . The blade coupler  33  is configured to couple the blade assembly  28  to handpiece  32 . The blade coupler  33  includes the aspiration control mechanism  34  as well as variety of components facilitating control over several functions (e.g., cutting, rotation, etc.) of blade assembly  28 . The transition assembly  42  is configured as a distal extension of the housing  38  of handpiece  32  and joins blade coupler  33  to handpiece  32 . In some configurations, the transition assembly  42  is omitted with blade coupler  33  being directly connected to the housing  38  of the handpiece  32 . While  FIGS. 2-7B  illustrate blade coupler  33  as positioned separate from (and distal to) housing  38 , in yet other configurations, the functions of blade coupler  33  are incorporated within the housing  38  of handpiece  32 . 
     In addition, in some embodiments, the surgical instrument  22  includes an optional control assembly  40  (referenced generally) configured to provide user control over a rotational position of a component of the blade assembly  28  as described below. In one aspect, control assembly  40  includes a rotatable wheel  41  configured to actuate a translation mechanism (not shown) within transition assembly  42  (or alternatively within housing  38 ), which in turn causes rotation of components of the blade assembly  28 , as further described later in association with  FIGS. 5-7B . 
     The blade assembly  28  can assume a variety of forms, and in some configurations includes an outer member assembly  50  having an outer member  52 , and an inner member assembly  54  having an inner member  56 . In general terms, the inner member  56  is rotatably disposed within the outer member  52 , with other components of the assemblies  50 ,  54  defining portions of the blade coupler  33  to effectuate connection to the handpiece  32 . Regardless, the outer and inner members  52 ,  56  extend distally from the handpiece  32 , and combine to form the cutting implement  30  as described below. As a point of reference, while the blade assembly  28  is shown as including two of the members  52 ,  56 , in other configurations, three or more co-axially assembled members can be provided. Further, the blade assembly  28 , and in particular the members  52 ,  56 , can have a linear or straight configuration as shown, or can alternately have a curved construction (such as by the inclusion of a curved member encompassing at least a portion of the outer member  52 ). 
     In one aspect, the aspiration control mechanism  34  also can assume a variety of forms, and in some configurations forms a part of blade coupler  33  with the user interface port  35  (also shown in  FIG. 1 ) located distally of handpiece  32 , as will be further described in association with FIGS.  3 A and  5 - 6 . In one aspect, aspiration control mechanism  34  defines an aspiration control pathway  65  ( FIGS. 5-6 ) that forms a segment of fluid pathway  36  between cutting implement  30  and negative pressure source  24 . The aspiration control mechanism  34  enables a user to control the amount of aspiration or vacuum at cutting implement  30  via selectively positioning their finger over the user interface port  35  while using the same hand to hold the handpiece  32  in position relative to the treatment site. In one aspect, user interface port  35  enables a comfortable placement of the control finger as it extends forward (and on a side of the handpiece  32 ) relative to the rest of their hand, which is gripping the handpiece  32 . 
     As shown in  FIG. 2 , in some configurations, handpiece  32  also includes an aspiration port  39  and a wiring conduit  208 . The aspiration port  39  is configured for connection to fluid pathway  36  and negative pressure source  24  (via port  37  and tubing  47  shown in  FIG. 1 ). The wiring conduit  208  is configured to route wiring from a motor (shown as motor  202  in  FIG. 7B ) and/or other components from the housing  38  of handpiece  32  to power source  26 . 
     With further reference to  FIG. 3A , with some configurations, in addition to the outer member  52 , the outer member assembly  50  includes an aspiration hub  60 , an aspiration subassembly  61 , a collet  62 , an irrigation hub  64 . The outer member  52  is secured to the aspiration hub  60 , with the collet  62  facilitating attachment to the handpiece  32  as part of blade coupler  33 . Further, where provided, the irrigation hub  64  facilitates delivery of an irrigation fluid to the outer member  52 . Other constructions appropriate for assembling the outer member  52  to the handpiece  32  are also acceptable. Regardless, the outer member  52  is tubular in some embodiments, and forms a distal region  66 . The distal region  66 , in turn, forms in some configurations a cutting window  70  and an elevator tip  72  distal the cutting window  70 . 
     The distal region  66  can be an integrally formed component of the outer member  52 , or can be separately formed and assembled to other components (e.g., the distal region  66  can be formed and then attached to an appropriately sized, rigid metal tube in completing the outer member  52 ). Regardless, one construction of the distal region  66  in accordance with principles of the present disclosure is shown in greater detail in  FIG. 4A . As shown in  FIG. 4A , the distal region  66  forms a lumen  74  that is otherwise open at the cutting window  70  (and continues proximally through at least a substantial portion of a remainder of the outer member  52  ( FIG. 3A )). With this mind, the cutting window  70  is defined by a cutting window wall  76 . A recessed portion  78  is formed in the distal region  66  about at least a proximal portion of the cutting window wall  76 , such that the distal region  66  tapers in wall thickness along the recessed portion  78 . As shown in  FIG. 4A , in one embodiment the cutting window  70  can have a tear drop-like shape in longitudinal length, decreasing in lateral perimeter width from a distal segment  80  to a proximal segment  82 . 
     The elevator tip  72  extends distal the cutting window  70 , terminating at a sharpened or blade edge  84 . In this regard, the elevator tip  72  is closed relative to the lumen  74 . In one embodiment, the elevator tip  74  is defined by opposing, first and second surfaces  86 ,  88 . The distal region  66  can assume a variety of forms, for example, including the forms described in U.S. patent application Ser. No. 11/938,625, filed Nov. 12, 2007, and entitled “Systems and Methods For Surgical Removal of Brain Tumors”, the teachings of which are incorporated herein by reference. 
     The above construction of the elevator tip  72  (e.g., curved surfaces, increased width, and the blade edge  84 ) combine to provide the elevator tip  72  with a curette-like form. As described below, the elevator tip  72  is highly amenable for interfacing with the delicate tissues encountered during brain surgery (as well as other challenging treatment sites). The blade edge  84  promotes partial separation or isolation of tumor tissue from the brain and other normal tissue, with the curved surfaces  86 ,  88  assisting in isolating or separating the tumor from other tissue. In other configurations in accordance with the present disclosure, however, the elevator tip  72  can be eliminated. For example, the distal region  66  can terminate at the cutting window  70  that is otherwise axially and radially open to the lumen  74 . Alternatively, the cutting window  70  can be formed in the distal region  66  as a side (or radial) window, with the outer member  52  having a relatively uniform outer diameter distal the cutting window  70 . 
     Returning to  FIG. 3A , the inner member assembly  54  includes the inner member  56 , as well as an inner member hub  100 . As described below, the inner member hub  100  maintains the inner member  56 , and facilitates connection of the inner member assembly  54  (as part of blade coupler  33 ) to a motor  202  (represented schematically and also shown in  FIG. 7B ). Thus, the inner member hub  100  can assume a variety of forms. Regardless, with some constructions, the inner member  56  is tubular, forming a distal cutting tip  102 . Moreover, in some configurations, the inner member  56  also forms a proximal aspiration window  103  exposing access to lumen  105 . Proximal aspiration window  103  provides just part of aspiration control mechanism  34  and the fluid pathway  36  that enables fluid communication between the aperture  168  of distal cutting tip  102 , user interface port  35 , and negative pressure source  24 , as further described later in association with  FIGS. 5-6 . 
     In addition, while proximal aspiration window  103  is shown in  FIG. 3A  as having a generally rectangular shape, in some other configurations proximal aspiration window  103  can assume other forms such as a circular, elliptical, or polygon shape. Moreover, as illustrated in  FIG. 3B , in some other configurations, proximal aspiration window  103  takes the form of an array  160  of holes  162  arranged in one or more rows along a wall of the inner member  56 . Alternatively, as shown in  FIG. 3C , proximal aspiration window  103  can take the form of an array  164  of holes  166  arranged in one or more spiral patterns about the wall of the inner member  56 . In either case, holes  162 ,  166  provide a fluid communication path through a proximal portion of the inner member  56 , with array  162  or  164  configured to be resistant to occlusion from tissue, fluids or other interferents. 
     In yet other configurations, and as shown in  FIG. 4B , the cutting tip  102  can include a series of serrations or teeth  167 . With this but one acceptable configuration, the teeth  167  are formed about an aperture  168  that is otherwise open to a lumen  105  defined by the inner member  56 . As described below, the aperture  168  and the lumen  105  serve as an aspiration outlet of the fluid pathway  36  ( FIG. 1 ) otherwise employed for aspirating a treatment site. Alternatively, the cutting tip  102  can assume other forms that may or may not include an aperture fluidly connected to a lumen. For example, the cutting tip  102  can be a closed burr. 
     In some configurations, fluid pathway  36  ( FIG. 1 ) includes a segment defining an aspiration control pathway  65  ( FIGS. 5-6 ) which establishes fluid communication between user interface port  35  and lumen  105  within inner member  56 . In one aspect, as shown in  FIG. 3A , aspiration control pathway  65  is defined by several components of blade coupler  33 , including aspiration hub  60 , aspiration subassembly  61 , collet  62 , irrigation hub  64 , and portions of inner member  56 . 
     While aspiration hub  60  can assume other forms, in one configuration as shown in  FIG. 3A , aspiration hub  60  defines a generally tubular member sized and shaped for slidable insertion within irrigation hub  64  and collet  62 , as later shown in  FIGS. 5-6 . Aspiration hub  60  includes a distal end  107 , a proximal end  108 , a distal lumen  120  for receiving outer member  52  (with inner member  56  arranged coaxially therein), and a proximal aspiration chamber  152  (shown in  FIGS. 5-6 ). In some constructions and as shown in  FIGS. 3A ,  5 - 6 , aspiration hub  60  includes a series of grooves  118  extending circumferentially about an outer surface of aspiration hub  60  with the respective grooves  118  being spaced apart from each other along a length of hub  60 . An irrigation channel  110  is interposed between a distal one and an intermediate one of the respective grooves  118  while an aspiration channel  112  is interposed between the intermediate one and a proximal one of the respective grooves  118 . In one aspect, aspiration channel  112  further defines a hole  122  to provide access to and fluid communication with a proximal aspiration chamber  152  (shown in  FIGS. 5-6 ) formed within aspiration hub  60 . In some configurations, adjacent proximal end  108 , aspiration hub  60  also includes an extension portion  114  and a rotation-engaging mechanism  116  configured to be engaged by a portion of control assembly  40 , as further described later in association with  FIG. 7A . The rotation-engaging mechanism  116  of aspiration hub  60  is configured to translate rotational motion from the control assembly  40  to cause rotation of outer member  56 . 
     Referring to  FIG. 3A , seals  130  (e.g., O-rings) are provided for slidably fitting within the respective grooves  118 , as further shown in  FIGS. 5-6 , to cause sealing of aspiration hub  60  relative to an inner surface of irrigation hub  64 . 
     In some configurations, an aspiration subassembly  61  is provided and defines a portion of aspiration control pathway  65  extending within blade coupler  33 . While aspiration subassembly  61  can assume a variety of forms, in some configurations, aspiration subassembly  61  comprises a generally tubular shaped sleeve  140  sized and shaped to fit within the proximal aspiration chamber  152  of aspiration hub  60 . As shown in FIGS.  3 A and  5 - 6 , the sleeve  140  generally defines a lumen  152  extending between a distal end  153  and a proximal end  154 . In some configurations, sleeve  140  further includes a proximal wall region  150  defining a generally continuous wall and a distal window region  158  defining at least one window  156  (two windows  156  are shown in  FIG. 3A ) exposing access to lumen  152 . 
     In some configurations, aspiration subassembly  61  further includes one or more seals  142  and a plug  144  arranged to sealingly secure sleeve  140  within aspiration proximal chamber  152  of aspiration hub  60 , as further illustrated in association  FIGS. 5-6 . 
     Referring again to FIGS.  3 A and  5 - 6 , while irrigation hub  64  can assume many forms, in some configurations, irrigation hub  64  includes a generally tubular shell defining a lumen  133  extending between a distal end  131  and a proximal end  132 . In addition, irrigation hub  64  includes an irrigation port  134  and an aspiration aperture  136 . The irrigation port  134  is configured for fluid connection to a fluid source (not shown). The aspiration aperture  136  is sized, shaped, and positioned for fluid communication with user interface port  35  of collet  62  and with hole  122  (within aspiration channel  112 ) of aspiration hub  60 , as further illustrated in  FIGS. 5-6 . 
     Referring again to FIGS.  3 A and  5 - 6 , collet  62  of blade coupler  33  defines an outer shell sized and shaped to enclose and cover other components of blade coupler  33 , including irrigation hub  64 , aspiration hub  60 , and aspiration subassembly  61  in their assembled form. In addition, collet  62  defines a lumen  63  sized to slidably receive and mount outer member  52 . In general terms, collet  62  holds these components together, enabling each of these components to accomplish their respective functions to support operation of cutting implement  30  at a treatment site. In one aspect, with these components acting in a cooperative relationship as will be described further in association with  FIGS. 5-7B , a user can control a level of vacuum at cutting implement  30  ( FIG. 1 ) via selective placement of their finger relative to user interface port  35  of aspiration control mechanism  34  on collet  62 . Because the aspiration control mechanism  34  is integrated within blade coupler  33  (as a distal extension of handpiece  32 ), a user can more effectively control vacuum pressure at cutting implement  30  without awkward positioning of their hand and fingers about the handpiece  32 . Instead, arranging the user interface port  35  on side portion of collet  62  (distal to housing  38  of handpiece  32  as shown in  FIG. 1 ) enables a more natural placement of a user&#39;s finger in a position distal to the rest of their hand which grasps the housing  38  of handpiece  32 . 
     Final construction of the blade assembly  28  and blade coupler  33 , which include outer member assembly  50  and inner member assembly  52  is shown in  FIGS. 5-7A , with  FIGS. 5 and 6  providing cross-sectional views and  FIG. 7A  providing a perspective view. In general terms, the outer member  52  is secured via lumen  120  of the aspiration hub  60  (and therefore relative to lumen  63  of collet  62 ), which is in turn is received within the irrigation hub  64 . The irrigation hub  64  comprises an inner shell that is slidably inserted and secured within the outer shell defined by collet  62 . With these general relationships in mind, further details about the construction and interaction of these components will be described. 
     Referring to  FIGS. 5-7A  and as previously mentioned, seals  130  effectuate a fluid-tight seal between the irrigation hub  64  and the aspiration hub  60 . With this construction, then, an irrigation liquid (not shown) is supplied through port  134  for delivery to the lumen  74  of the outer member  52  via a sealed gap  170  between the respective hubs  60 ,  64  (as defined by irrigation channel  110 ) and a bore  109  ( FIGS. 3A and 5 ) formed in a proximal region of the outer member  52 . In one aspect, the irrigation channel  110  extends circumferentially about an outer surface of aspiration hub  60  and generally transverse to a longitudinal axis of the aspiration hub  60 . The assembled hubs  60 ,  64  are coaxially received with the collet  62 , with the outer member  52  extending distal the collet  62  as shown. Other constructions capable of effectuating flow of irrigation liquid to the outer member  52  are also envisioned; in yet other configurations, the irrigation hub  64  (as well as any other irrigation component) can be eliminated. 
     Referring to  FIGS. 5-6 , the aspiration control mechanism  34  can assume a variety of forms, and in some embodiments, defines the aspiration control pathway  65  forming a segment of fluid pathway  36 . In one aspect, the sealed, coaxial relationship of the aspiration hub  60  within the irrigation hub  64  also defines a gap  174  between seals  130  (within grooves  118 ) and the aspiration channel  112 . However, unlike the irrigation channel  110 , gap  174  is open to user interface port  35  via hole  136  of irrigation hub  64 . Moreover, gap  174  is also open to proximal vacuum chamber  152  of hub  60  via hole  122  in the aspiration channel  112 . 
     Accordingly, while not intending to be limited by directional terminology, the aspiration control pathway  65  begins, in one respect, with user interface port  35  of collet  62  ( FIG. 6 ), extends through hole  136  of irrigation hub  64  ( FIG. 6 ), into aspiration channel  174  ( FIG. 5 ) of aspiration hub  60 , through hole  122  from the gap  174  defined by aspiration channel  112  ( FIG. 5 ) and down into proximal aspiration chamber  152  of aspiration hub  60  ( FIG. 5 ), into window portion  156  of sleeve  140  (see  FIGS. 5 and 3A ) and through lumen  152  of sleeve  140  for passage into lumen  105  of inner member  56  via proximal aspiration window  103  ( FIG. 5 ). Aspiration control pathway  65  joins to the rest of fluid pathway  36  via lumen  105  of inner member  56  which extends distally to aperture  168  at distal cutting tip  102  and which extends proximally through inner member hub  100  for passage through an interior of handpiece  32  for connection to negative pressure source  24 . More details regarding the aspiration control pathway  65  in relation to the structure of the handpiece  32  are described and illustrated in association with  FIG. 7B . 
     Accordingly, in general terms, the aspiration control pathway  65  establishes a segment of the fluid pathway  36  internally within blade coupler  33  (as an extension of handpiece  32 ) to establish fluid connection between the source of negative pressure  24  to the cutting implement  30  (via lumen  105  of inner member  50 ). More particularly, in some configurations, the aspiration control mechanism  34  (including its control pathway  65 ) is configured without an external structure on the housing  38  of handpiece  32 , which could otherwise hinder a surgeon&#39;s handling of surgical instrument  22 . 
     In one aspect, the introduction of proximal vacuum window  103  of inner member  50  enables an internal path for aspiration control mechanism  34 , with proximal wall region  150  of sleeve  140  redirecting the fluid pathway distally into proximal aspiration chamber  152  (of aspiration hub  60 ) where distal window region  156  of sleeve  140  permits fluid communication between lumen  152  of sleeve  140  and proximal aspiration chamber  152 . From this point, hole  122  in the aspiration channel  112  provides a generally direct fluid path from proximal aspiration chamber  152  to user interface port  35 , since hole  122  is vertically aligned with hole  136  of irrigation hub  64  and with the hole in collet  62  that defines user interface port  35  on an exterior of blade coupler  33 . 
     In other configurations, aspiration control pathway  65  not limited to particular arrangement shown in  FIGS. 1-7B  provided that a pathway extends from some portion of lumen  105  of inner member  50  (such as proximal vacuum window  103 ) internally within a distal portion of handpiece  32 , a blade coupler  33 , or similar structure to an exteriorly positioned user interface port (e.g., user interface port  35 ) accessible by the finger of a surgeon. Accordingly, in general terms, aspiration control pathway  65  as part of aspiration control mechanism  34  defines an exclusively internal fluid pathway bridging a user interface port (i.e., an exterior opening of a handpiece or as part of a distal extension of the handpiece) to a larger fluid pathway  36  extending between a cutting implement  30  and a source of negative pressure  24 . 
     As noted above, with some embodiments, the fluid pathway  36  further extends through the lumen  105  of the inner member  56  ( FIGS. 3A ,  4 B, and  5 - 6 ), and is open at the aperture  168  ( FIG. 4B ). However, with alternative configurations, the aspiration outlet at the cutting implement  30  can be provided in other forms that may or may not include the aperture  168  of the inner member  56  (e.g., aspiration can be provided via the outer member  52 , via a separate tube provided with the blade assembly  28 , etc.). Thus, the aspiration control mechanism  34  affords the user the ability to control a level of vacuum applied at the cutting implement  30 . 
     As described below, control over the aspiration delivered at the cutting implement  30  ( FIG. 1 ) is selectively effectuated by covering or uncovering the user interface port  35 . In particular, a level or rate or vacuum delivered to or experienced at the aperture  168  ( FIG. 4B ), or other aspiration outlet configuration, will increase as the user interface port  35  ( FIG. 1-3A ) is increasingly covered, and vice-versa. With this in mind, the user interface port  35  has, in some configurations, a larger surface area as compared to the aspiration outlet provided at the cutting implement  30  through which suctioning is otherwise applied. For example, with some constructions, the aspiration outlet provided with the cutting implement  30  is the aperture  168  formed by the inner member  56  ( FIG. 3 ). Commensurate with this description, then, a size of the user interface port  35  can be selected to be greater than a size of the aperture  168 . As a result, when the user interface port  35  is entirely unobstructed, a vacuum level at the cutting implement  30  (i.e., at the aperture  168 ) is substantially zero in that the user interface port  35  provides a path of least resistance for negative pressure within the fluid pathway  36 . Moreover, in some embodiments, the size of the user interface port  35  can be increased even more to be substantially larger than size of the aperture  168  to insure the elimination of suction at the cutting implement  30 . Further, a user will readily “sense” vacuum or suction at the user interface port  35 , and is thus provided with direct, tactile feedback as to a level of vacuum being applied at the cutting implement  30 . Also the user interface port  35  affords essentially infinite control over the applied vacuum (between zero and maximum generated at the source of negative pressure  24 ) due to the absence of pre-established indexes or other stop mechanism along the aspiration control mechanism  34 . 
     In some configurations, the user interface port  35  is embodied in a tear-drop shape (on an exterior of collet  62  of blade coupler  33 ) to yield user interface port  194 , as shown in  FIG. 7A . The variable cross-sectional area presented by the tear-drop shape enables more precise control over the level of aspiration during finger control by the surgeon. 
     In yet other configurations and as shown in  FIG. 7A , collet  62  is provided with a rotatable cover  185  configured to selectively cover the user interface port  194  (or user interface port  35  having a circular shape). Thus, rotatable cover  185  enables the surgeon to block user interface port  194  for a period of time, in case it is desired to maintain closure of user interface port  194  (or user interface port  35 ) for an extended period of time. Later, the surgeon can simply rotate cover  185  away from user interface port  194  when it is desired to resume finger-controlled access to user interface port  194  (or a user interface  35  having a circular shape). 
     Final construction of the blade assembly  28  is further shown in  FIG. 7A . As a point of reference, while the outer and inner members  52 ,  56  have been shown in as being linear, in other configurations, one or more bends or curves can be formed and/or additional tubular member(s) provided. The inner member  56  is received within the lumen  74  ( FIGS. 5-6 ) of the outer member  52 , and is attached to the inner member hub  100 . The inner member hub  100 , in turn, is positioned proximal the aspiration hub  60  and is rotatable relative thereto, such that rotation of the inner member hub  100  effectuates rotation of the inner member  56  relative to the outer member  52 . Further, the cutting tip  102  of the inner member  56  is positioned at the cutting window  70  of the outer member  52 . Thus, the cutting tip  102  is exteriorly exposed via the cutting window  70  for performing a cutting or debriding procedure. Finally, the distal region  66  of the outer member  52  (e.g., the cutting window  70  and the elevator tip  72 ) combine with the cutting tip  102  to form the cutting implement  30 . Aspiration is effectuated at the cutting implement  30  via the aperture  168  provided with the inner member  56  (with the aperture  168  being exteriorly open through the cutting window  70 ). Alternatively, aspiration or suctioning at the cutting implement  30  can be provided by the outer member  52 , a separate tubing carried by the cutting implement  30 , etc. Similarly, irrigation is provided at the cutting implement via the outer member  52 /cutting window  70 , although in other embodiments, an additional irrigation supply tube (carried with or separate from the cutting implement  30 ) can be provided. 
     Returning to  FIG. 2 , the handpiece  32  and blade coupler  33  can assume a variety of forms that promote manipulation of the blade assembly  28 /cutting implement  30  by a user, as well as powered movement of the inner member  56  relative to the outer member  52 . 
     The optional control assembly  40  shown in  FIG. 1  facilitates rotation of the outer member  52  relative to the inner member  56  as described below, and can assume a variety of forms. In some constructions and as shown in  FIG. 7A , the control assembly  40  comprises an actuator  190  including a rotatable finger controller  192  and a translation mechanism  194 , which is configured to translate motion of actuator rotatable finger controller  192  into rotation of outer member  52 . The rotatable finger controller  192  can be akin to a wheel  41  as shown in  FIG. 1 , and is rotatably assembled to the housing  38  (or as represented by  200  in  FIG. 7B ). The translation mechanism  194  is configured to translate rotation of the rotatable finger controller  192  to the aspiration hub  60 , and thus to the outer member  52 . In this regard, translation mechanism  194  includes features adapted to interface with the rotation-engaging mechanism  116  of the aspiration hub  60 . More particularly, and as best shown in  FIG. 7A , in some constructions, the rotation-engaging mechanism  116  of the aspiration hub  60  is a series of circumferentially disposed indentations  196 . In one arrangement, translation mechanism  194  includes features configured to interface with the indentations  196 , akin to a ball and detent relationship. With this configuration, then, rotation of the rotatable finger controller  192  (e.g. wheel  41  in  FIG. 1 ) is translated via translation mechanism  194  to the aspiration hub  60 . Rotation of the aspiration hub  60 , in turn, rotates the outer member  52 . Because the aspiration hub  60  is not otherwise affixed to other components of the inner member assembly  54 , rotation of the aspiration hub  60  results in rotation of the outer member  52  relative to the inner member  56 . Importantly, rotation of the outer member  52  can be achieved by a user without overt movement of the housing  38  of handpiece  32  in  FIG. 1  (or housing  200  as schematically represented in  FIG. 7B ). While grasping the housing  38  in his or her hand, the surgeon simply rotates the wheel  41  (represented schematically as rotatable finger controller  192  in  FIG. 7A ) with a finger (or thumb) of the same hand that is otherwise holding the housing  38  of the handpiece  32  shown in  FIG. 1 . 
     Returning to  FIG. 2 , the handpiece  32  can assume a variety of forms that promote manipulation of the blade assembly  28 /cutting implement  30  by a user, as well as powered movement of the inner member  56  relative to the outer member  52 . For example,  FIG. 7B  illustrates one construction of the handpiece  32  in accordance with the principles of the present disclosure. As a point of reference, for ease of illustration, certain proximal portions of the aspiration control mechanism  34  ( FIG. 2 ) as they extend from blade coupler  33  through transition assembly  42  (such as the details of translation mechanism  194 ) are omitted from the view of  FIG. 8 . Further, the handpiece  32  is shown in  FIG. 8  as being assembled to components of blade coupler  33 , including portions of the blade assembly  28 . With this in mind, the handpiece  32  includes a housing  200 , the control assembly  40 , a motor  202  (shown schematically in  FIG. 7B ), and a drive coupling  204 . The motor  202  is secured within the housing  200 , with the housing  200  forming a conduit  208  through which wiring (not shown) otherwise providing power to the motor  202  can extend. Further, the housing  200  preferably includes an output shaft  210  (which also defines a passage  214 ) and an aspiration port  39  for fluidly connecting the blade assembly  28  to the source of negative pressure  24  ( FIG. 1 ) as described below. The drive coupling  204  mechanically connects the motor  202  to the inner member hub  100 , and thus the inner member  56 . To this end, a wide variety of constructions can be employed. With some configurations, however, the drive coupling  204  includes the output shaft  210  which is rotatably linked (e.g., geared) to a drive shaft  212  of the motor  132 . The output shaft  210  can assume various forms, and with some constructions forms the passage  214  that, upon final assembly, fluidly connects the aspiration port  39  with a passageway  216  (see  FIGS. 5-6 ) formed by the inner member hub  100  (and thus with the lumen  105  of the inner member  56  otherwise assembled to the passageway  216 ). Optional dynamic seals  218  can be included to better ensure a fluid-tight seal between the passage  214  and the aspiration port  39 . 
     The control assembly  40  can assume a variety of other forms apart from the description provided above, for example as described in U.S. patent application Ser. No. 10/854,020 filed Sep. 22, 2004 and entitled “Surgical Cutting Instrument,” the teachings of which are incorporated herein by reference. Conversely, with other constructions of the surgical instrument  22 , the control assembly  40  is omitted (i.e., the outer member  52  cannot be independently rotated relative to the inner member  54 ). Where provided, however, rotation of the outer member  52  relative to the inner member  56  allows the user to selectively shield the cutting tip  102  from unintentionally contacting, and thus possibly damaging, delicate tissue of the brain and surrounding anatomy during a brain tumor debridement procedure. For example, as shown in  FIG. 8A  (in which only a portion of the outer member  52  is illustrated for purposes of clarity), a rotational position of the outer member  52  relative to the inner member  56  can be selected such that the cutting tip  102  is exteriorly exposed at the cutting window  70 . With this orientation, the cutting tip  102  can contact and cut tissue adjacent the cutting implement  30 . Conversely, the outer member  52  can be rotated relative to the inner member  56  such that the cutting tip  102  is within the outer member  52 , as shown in  FIG. 8B . With this arrangement, then, the outer member  52  prevents the cutting tip  102  from contacting, and possibly damaging, tissue. Along these same lines, the outer member  52  can be rotated to position or “face” the cutting window  70  at a desired location (e.g., a brain tumor) without movement of the handpiece  32  ( FIG. 1 ) via the control assembly  40  ( FIG. 1 ). That is to say, once the cutting implement  30  is delivered to a treatment site, the precise location at which cutting will occur (i.e., the cutting window  70 ) can be controlled by movement of the control assembly  40  ( FIG. 1 ) (or as schematically represented by rotatable finger controller  192  in  FIG. 7A ). Accordingly, the surgeon will not be forced to contort his or her hand(s) to achieve a desired point of cutting/position of the cutting window  70 . 
     While the system  20  is generally useful in the surgical treatment (e.g., removal) of tumors, the system  20  is highly useful in the removal or reduction of brain tumors. In this regard, and with additional reference to  FIG. 9A , treatment of a brain tumor  250  in accordance with aspects of the present disclosure includes forming an access opening in the patient&#39;s skull  252  (e.g., a conventional craniotomy). As a point of reference,  FIG. 9A  schematically illustrates other anatomy, including the dura  254 , the arachnoid  256 , the pia  258 , and the cortex  260 . The brain tumor  250  is shown as projecting from a natural anatomy of the cortex  260 , exteriorly “covered” by the pia  258 . With other procedures, the brain tumor  250  may be internal or embedded within the cortex (or other brain tissue)  260 . Regardless, once a treatment site  262  at which the brain tumor  250  is located has been exposed, the system  20  is operated to remove at least some, preferably all, of the brain tumor  250 . 
     The cutting implement  30  is deployed to the treatment site  262 . During delivery of the cutting implement  30 , the power supply  26  ( FIG. 1 ) is inactive, such that the inner member  56  ( FIG. 3A ) does not move relative to the outer member  52  of blade assembly  28 . Further, the source of negative pressure  24  ( FIG. 1 ) may or may not be activated during initial placement of the cutting implement  30 . That is to say, a negative pressure condition may or may not be established along the fluid pathway  36 . Where the source of negative pressure  24  is activated, however, the user manually effectuates control over delivery of negative pressure to the cutting implement  30 , such as by leaving the user interface port  35  ( FIGS. 1-3A ) associated with the aspiration control mechanism  34  uncovered. As described above, this arrangement causes virtually all of the negative pressure generated by the source of negative pressure  24  to be delivered to the user interface port  35 , and thus not the aspiration outlet/aperture  168  of the cutting implement  30  in a manner that might otherwise negatively impact surrounding tissue of the treatment site  262 . 
     Once the cutting implement  30  is positioned adjacent the brain tumor  250 , the surgeon manipulates the handpiece  32  so as to position the elevator tip  72  (where provided) partially between the brain tumor  250  and surrounding tissue of the treatment site  262 . Where provided, the control assembly  40  (including wheel  41  as shown in  FIG. 1 ) can be operated by the surgeon to rotate the elevator tip  72  to a desired spatial orientation relative to the treatment site  262  without overt twisting/contortion of the surgeon&#39;s hand(s). For example, as shown in  FIG. 9B , the elevator tip  72  is positioned between the brain tumor  250  and a portion of the pia mater  258 . Depending upon the particular location of the brain tumor  250 , other non-tumor tissue of the brain anatomy may also or alternatively be implicated (e.g., the dura  254 , arachnoid  256 , cerebral cortex  260 , etc.), with the elevator tip  72  partially isolating the brain tumor  250  from this tissue. Regardless, the elevator tip  72  at least partially separates or isolates the brain tumor  250  from the surrounding tissue with the blade edge  84  ( FIG. 4A ) possibly partially severing a portion of the brain tumor  250  away from the surrounding tissue. For example, the blade edge  84  can be manipulated to pierce the pia  258  at a relatively precise location in close proximity to the tumor  250 . Further, by controlling (minimizing) aspiration at the cutting implement, unnecessary damage to the pia  258  (and other tissue) is avoided. The handpiece  32  can be further manipulated to cause the elevator tip  72  to pry the brain tumor  250  away from the surrounding tissue. 
     Once the elevator tip  72  is desirably positioned, the cutting tip  102  (referenced generally in  FIG. 7A ) is placed into contact with the brain tumor  250 . For example, the outer member  52  is moved (e.g., rotated) such that the cutting window  70  “faces” the brain tumor  250 . Further, with some techniques, the aspiration control mechanism  34  is manually operated to effectuate delivery of negative pressure to the cutting implement  30 , thus drawing or suctioning the brain tumor  250  into contact with the cutting tip  102 . For example, the surgeon can at least partially obstruct the user interface port  35  ( FIGS. 1-3A ), effectuating a more complete fluid connection between the source of negative pressure  24  and the aspiration aperture  168 . 
     Due to the relatively compact and streamlined size and shape of the handpiece  32 , the surgeon can readily, visually confirm desired placement and orientation of the cutting implement  30 , and in particular the elevator tip  72  and the cutting window  70 /cutting tip  102 , relative to the brain tumor  250  and the surrounding tissue. Once the surgeon is satisfied with placement of the cutting implement  30 , the power supply  26  is activated, thus causing the inner member  56  ( FIG. 3 ) to move relative to the outer member  52 . This action, in turn, causes the cutting tip  102  to move within the cutting window  70 , cutting or debriding the contacted brain tumor  250 . With some constructions, the motor  202  ( FIG. 7B ) operates to rotationally oscillate the cutting tip  102  relative to the cutting window  70 . As part of this debriding procedure, the aspiration control mechanism  34  can be manually operated (e.g., movement of the surgeon&#39;s finger relative to the user interface port  35 ) to effectuate an increased vacuum level at the cutting implement  30 , thus removing debrided brain tumor tissue from the treatment site  262 . 
     During the debriding procedure, the surgeon can periodically confirm continued desired positioning of the cutting implement  30  relative to the brain tumor  250  and the surrounding tissue  256 . Where, for example, it is determined that a differing point of cutting along the brain tumor  250  is desired, the outer member  52  can be rotated relative to the inner member  56  ( FIG. 3 ), thereby altering a spatial position of the cutting window  70 , and thus a point of contact of the cutting tip  102  with the brain tumor  250 . For example, the wheel  41  of control assembly  40  shown in  FIGS. 1-2  (and also represented by rotatable finger controller  192  shown in  FIG. 7A ) can be manipulated by the user&#39;s finger, causing a rotational position of the outer member  52  relative to the inner member  56  to change. Once again, and throughout the entire procedure, the level of vacuum or rate of aspiration can be manually changed at any time by the surgeon, for example by simply covering more or less of the user interface port  35  ( FIGS. 1-7B ). 
     The surgical systems and methods of the present disclosure provide a marked improvement over previous surgical techniques. The cutting implement, including the distal cutting tip and optional elevator tip, can safely remove selected target tissue, but not damage the surrounding tissues. Further, with selective variable aspiration, the target tissue can be isolated from the surrounding tissue for subsequent removal and more aggressive cutting. Moreover, by integrating an aspiration control mechanism within a blade coupler (or directly within a handpiece), the handpiece is not encumbered with extraneous structure an exterior of the handpiece, thereby facilitating nimble handling of the handpiece by the surgeon as well providing convenient finger control over aspiration. Further, the ability to rotate the outer member assists in protecting any delicate surrounding tissue (e.g., dura, arachnoid, pia, etc.) such as when the cutting implement is used to treat brain tumors or to protect other delicate tissues (e.g., vocal cords, esophagus) when treating tumors or lesions in the airway. 
     Although the present disclosure has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the present disclosure.