Abstract:
The present invention is directed to an apparatus and method for supportably positioning an implantable hearing aid actuator within a patient&#39;s skull. The improved apparatus includes a carry device for carrying an implantable hearing aid actuator at a first end, a swivel device for pivotably supporting the carrier device, and a mounting device for mounting the apparatus to a patient&#39;s skull. To facilitate installation, a swivel device may be provided in a unitary manner so as to provide for selective placement and securement as a single unit to the mounting device. To yield enhanced depth positioning, the carrier device may be selectively advancable relative to the swivel device, and the carrier device may comprise two or more members interconnected for selective advancement of one relative to other. In the later regard, the carrier device may include at least a first member which telescopes coaxially relative to a second member.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an apparatus and method for supportably positioning an implantable hearing aid actuator within a patient&#39;s skull, and more particularly, to a positioning apparatus and method that provides ease-of-installation, range-of-application, actuator loading and depth positioning advantages. 
     BACKGROUND OF THE INVENTION 
     Several types of implantable hearing aid devices have been proposed. Principally, such devices include those which utilize implanted electromechanical transducers for stimulation of the ossicular chain and/or oval window (see e.g., U.S. Pat. No. 5,702,342), and those which utilize implanted excitor coils to electromagnetically stimulate magnets affixed within the middle ear (see e.g., U.S. Pat. No. 5,897,486). For purposes hereof, such electromechanical transducers and excitor coils, as well other implanted devices that stimulate the ossicular chain and/or oval window will be collectively referred to as “implantable hearing aid actuators”. 
     In most instances, hearing aid devices of the above-noted nature entail supportable positioning of the given implantable actuator within a patient&#39;s skull. In many procedures, an opening is surgically defined in a patients skull and the implantable actuator is inserted through the opening for supportable positioning within the mastoid process. In conjunction with such implant procedures, precise placement and orientation of the implantable actuator can be of paramount importance to achieve best results. 
     To yield precise positioning a number of arrangements have been proposed, wherein implantable actuator(s) may supportably disposed for selective in-site positioning in multiple dimensions relative to a skull mounting device. While such arrangements have represented an advance in the art, they often entailed the positioning of a number of separate, hard-to-handle components, thereby adding to the complexity already associated with implant procedures. Additionally, the present inventors believe that further enhanced positioning of implantable actuators is achievable, particularly with respect to the depth profile which can vary significantly from patient to patient. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, a primary objective of the present invention is to provide an apparatus and method for supportably positioning an implantable hearing actuator at a desired location with enhanced ease-of-installation. Additional objectives are to provide an implantation apparatus and method that yields enhanced accuracy in implantable hearing aid actuator positioning and/or range-of-application advantages. Yet a further objective of the present invention is to provide an apparatus and method that facilitates accurate, contact loading of an electromechanical transducer relative to a patient&#39;s ossicle. 
     One or more of the above-noted objectives as well as additional advantages are provided in the inventive apparatus which includes a carrier device for carrying an implantable hearing aid actuator at a first end, and a swivel device for pivotably supporting the carrier device. Such pivotable support allows the first-end of the carrier device to be laterally pivotable in first and second dimensions relative to the swivel device. The apparatus further includes a mounting device for mounting the apparatus to a patient&#39;s skull, wherein the swivel device may be secured to the mounting device. 
     In one aspect of the present invention the swivel device is provided in a unitary fashion. That is, the swivel device is selectively positionable relative to and otherwise securable to the mounting device as a single unit. Such an arrangement simplifies installation procedures in conjunction with hearing aid implants. Further, to enhance actuator depth positioning, the carrier device and swivel device are preferably adapted to allow the carrier device to be selectively positioned in a third dimension relative to the swivel device. 
     Preferably, the unitary swivel device includes interconnected, opposing first and second holder members with a pivot member (e.g., a rotatable ball) captured between the first and second holder members. The pivot member may include an opening for supportably receiving the carrier device, wherein the carrier device is slidably positionable in the opening along a linear continuum of positions in the third dimension. As may be appreciated, pivotable movement of the carrier device will effect corresponding rotation of the pivot member relative to the interconnected first and second holder members. 
     In the later regard, the first and second holder members may be interconnected to permit a limited range of relative movement therebetween, thereby facilitating selective rotation of the pivot member upon pivotable movement of the carrier device. Relatedly, the inventive apparatus may further comprise a locking member interconnectable to the mounting device to selectively apply a compressive force to and thereby restrict relative movement between the first and second holder members, wherein a selected angular orientation between the carrier device and the mounting device may be maintained by the locking member. 
     Further, the locking member may also be employable to lock-in a selected linear position of the carrier device relative to the swivel device. More particularly, the pivot member may include a plurality of slits extending through an upper portion thereof to define a plurality of separated, upper portions of the pivot member. Correspondingly, the first holder member may comprise an aperture sized for contact positioning about the slitted portion of the pivot member. Consequently, when the locking member is interconnected to the mounting device to apply a compressive force to the first and second holders, such force will effect inward movement of the plurality of separated, upper portions to restrictably engage the carrier device. 
     In another aspect of the present invention, the carrier device may be interconnected to the swivel device in a manner that allows for selective advancement of the carrier device relative to the swivel device, wherein a first degree of actuator depth positioning latitude is provided; and, the carrier device may comprise at least a first carrier member and an interconnected second carrier member having a distal end connectable to an actuator, wherein the second carrier member is selectively advancable relative to the first carrier member to yield a second degree of depth positioning latitude. Such multiple depth positioning functionality not only facilitates accurate placement of an implantable hearing aid actuator but also facilitates a greater depth positioning range for an increased range of patient applications. In one arrangement, the first and second carrier members may be disposed coaxially and interconnected for selective, telescoping advancement of the second carrier member relative to the first carrier member. 
     Preferably, the first and second carrier members may be threadably interconnected, wherein driven rotation of the first carrier member effects a predetermined degree of linear travel by the second carrier member. In this regard, the swivel device may include an opening for supportably receiving the carrier device, wherein a top end of the first carrier member projects from the swivel device to provide ready access for driven rotation by an accessory tool. 
     In addition to first and second carrier members, the carrier device may further include a third carrier member, rotatably interconnected to the first carrier member, for restricting rotational movement of the second carrier member. In one arrangement, the second carrier member may include a linear slot while the third carrier member includes a projecting retention pin positioned within the slot of the second carrier member. As such, when the third carrier member is rotationally fixes (e.g., via use of a locking member as noted above) and the first carrier member is rotated, the third carrier member restricts rotation of the second carrier member, thereby causing the second carrier member to telescope away from both of the first and third carrier members. 
     In one embodiment, a mounting device is provided which includes a cylindrical barrel portion for supportably receiving a swivel device and carrier device interconnected thereto. The barrel portion includes a bottom end plate and is internally threaded, wherein the swivel device may be “locked-in” between an externally threaded locking member and the bottom end plate. The swivel device may include interconnected, top and bottom plate members with opposing central apertures having beveled edge surfaces for receiving a round pivot member therebetween. The pivot member is provided with a central opening therethrough for slidably receiving an outer support member of the carrier device. The carrier device further includes an internal shaft member rotatably interconnected at a top end to a top end of the outer support member, and interconnected at a bottom end to a telescoping member. In turn, a distal end of the telescoping member is interconnected to an electromechanical transducer actuator. 
     The entire carrier device may be selectively located at one of a linear continuum of positions relative to the swivel device to provide a first measure of depth positioning control. Further, the carrier device may be pivoted relative to the mounting device to provide for lateral positioning of the electromechanical transducer actuator. When a desired depth and angular orientation of the carrier device is established, such position may be “locked-in” by tightening the locking ring down on the swivel assembly. Then, the telescoping member of the carrier device may be selectively advanced to position the electromechanical transducer actuator in a desired contact position with the ossicular chain (e.g., contact with the incus bone) or oval window. 
     In view of the foregoing, it will apparent that an inventive method for positioning an implantable hearing aid actuator is also provided. The inventive method includes the steps of attaching a mounting device to a patient&#39;s skull and supporting a swivel device on the mounting device, wherein the swivel device pivotably supports a carrier device having an implantable hearing aid actuator interconnected thereto. The method further provides for the positioning of the carrier device so as to locate the implantable hearing aid actuator at a desired location within the patient&#39;s skull. 
     Preferably, the supporting step is achieved via the placement of the swivel device as a single unit into a support position on the mounting device. In one embodiment, this may be achieved by inserting the swivel device as a unit into a barrel portion of the mounting device and supportably engaging a bottom end plate of the barrel portion. 
     The positioning step of the inventive method preferably includes the sub-steps of pivoting the carrier device and interconnected implantable hearing aid actuator into a desired angular orientation relative to the mounting device within a patient&#39;s skull, and advancing the carrier device relative to the swivel device. Further, in an arrangement where the carrier device includes at least first and second carrier members, the positioning step may further include the sub-step of advancing the second carrier member relative to the first carrier member. 
     When an electromechanical transducer actuator is utilized, a desired contact location may be defined on the ossicular chain (e.g., the incus bone) or oval window within a patient&#39;s skull, wherein a probe tip of the electromechanical transducer actuator is brought into gradual contact with the contact location during positioning. In this regard, the inventive method may further provide for advancing the second carrier member relative to the first carrier member so as to provide a predetermined degree of loading by the probe tip on the contact location. 
     Numerous additional aspects and advantages of the present invention will become apparent to those skilled in the art upon consideration of further description that follows. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploited view of one embodiment of an inventive apparatus for supportably positioning an implantable hearing aid actuator within a patient&#39;s skull. 
     FIGS. 2A,  2 B,  2 C and  2 D illustrate an exploded view, an assembled side view, and two cross-sectional side views (i.e., taken along cross-section line AA of FIG.  2 B), respectively, of a swivel assembly embodiment shown in the embodiment of FIG.  1 . 
     FIGS. 3A,  3 B and  3 C illustrate an exploded view, an assembled top view and a cross-sectional side view (i.e., taken along cross-section line AA of FIG.  3 B), respectively, of a carrier assembly embodiment shown in the embodiment of FIG.  1 . 
     FIG. 4 is a cross-sectional view of the various components illustrated in FIG. 1 interconnected for use. 
     FIG. 5 illustrates positioning of the various components shown in FIG. 1 during an exemplary implant procedure. 
    
    
     DETAILED DESCRIPTION 
     The invention will now be further described with reference to the mounting apparatus embodiment  10  illustrated in FIG.  1 . Such description is for purposes of facilitating an understanding of the invention and other embodiments will be apparent to those skilled in the art. 
     The mounting apparatus  10  includes a carrier assembly  20 , a swivel assembly  40 , and a mounting assembly  60 . Such assemblies may be readily interconnected and disposed to cooperate in a manner that allows for selective, three-dimensional positioning of an implantable hearing aid actuator, such as exemplary actuator  80 , at a desired location within a patient&#39;s skull. 
     By way of general overview, the exemplary actuator  80  may be supportably connected to a first end  22  of the carrier assembly  20 . In turn, the carrier assembly  20  may be supportably received in an opening  42  provided in the swivel assembly  40  and the assembled carrier assembly  20 /swivel assembly  40  may be supportably interconnected to a mounting apparatus  62  attached to a patient&#39;s skull (e.g. via the insertion of skull attachment devices  70  through apertures  65  of mounting legs  63  into the skull). As will be further described, the interconnection between carrier assembly  20  and swivel assembly  40  provides for pivotable, lateral positioning of the first end  22  of the carrier assembly  20 , and of the actuator  80  interconnected thereto. Further, carrier device  20  and swivel assembly  40  may be provided so that carrier assembly  20  may be selectively secured along a continuum of positions within the opening  42  of the swivel assembly  40 , thereby facilitating advancement/retraction of the carrier assembly  20  and interconnected actuator  80 , in a depth dimension. Additionally, the carrier assembly  20  may be defined so that its first end  22  may be selectively advanced/retracted in the depth dimension relative to an outer support member  24  thereto. 
     As illustrated in FIG. 1, swivel assembly  40  may be provided in a unitary, or interconnected, form so that it may be readily positioned about the outer support member  24  of carrier assembly  20 , thereby facilitating positioning and interconnection of the swivel assembly  40  within the mounting apparatus  62 . In the later regard, it should be noted that in the illustrated embodiment swivel assembly  40  is configured for mating receipt in a predetermined orientation by a complimentarily configured barrel portion  64  of mounting apparatus  62 . Further, unitary swivel assembly  40  is sized to supportably rest upon an end plate portion  66  of mounting apparatus  62 . As will be further described, when carrier assembly  20  has been advanced/retracted and pivoted to be in a desired linear and angular position, a locking member  68 , positionable within a top end of the barrel  64  of mounting apparatus  62 , may be tightened against the top of swivel assembly  40  to “lock-in” the desired linear and angular position of carrier assembly  20 . 
     To facilitate such functionality, one embodiment of swivel assembly  40  will now be discussed in detail with reference to FIGS. 2A-2D. As illustrated, swivel assembly  40  includes opposing, top and bottom plate members  44   a  and  44   b , respectively, which are interconnected to capture a rotatable ball member  46  therebetween. In particular, the top and bottom plate members  44   a ,  44   b  include centrally aligned apertures  45   a ,  45   b , with opposing beveled, ring-shaped, edge surfaces  41   a ,  41   b , wherein the ball member  46  is seated between the beveled surfaces  41   a  and  41   b . The rotatable ball member  46  also includes an aperture  47  there through which, together with apertures  45   a ,  45   b , collectively define the opening  42  of swivel assembly  40 . In this regard, aperture  47  may be sized to slidably receive the outer support member  24 , yet restrain free relative movement therebetween. As will be appreciated, when carrier assembly  20  is positioned through opening  42 , pivotal movement of the carrier assembly  20  will cause rotation of the ball member  46 . In relation to such movement, apertures  45   a ,  45   b  are sized larger than aperture  47  so as to permit pivotal movement of carrier assembly  20  within a predetermined range of motion. By way of example, swivel assembly  20  may be provided so as to permit carrier assembly  20  to pivot up to 30° about and relative to a center axis passing through the apertures  45   a  and  45   b.    
     The top and bottom plate members  44   a  and  44   b  are interconnected by headed pins  48  which are inserted through apertures  50   a  and  50   b  of the top and bottom plate members  44   a  and  44   b , respectively. The apertures  50   b  defined in the bottom plate member  44   b  are sized for retentive press-fit receipt of the bottom ends of headed pins  48 . On the other hand, the apertures  50   a  defined in top plate member  44   a  are sized relative to the headed pins  48  to permit a small degree of linear travel therebetween (e.g., about 0.01″), thereby allowing the ball member  46  to rotate relative to the top and bottom plate members  44   a  and  44   b , absent the application of a compressive force on the swivel assembly  40 . For purposes of illustrating the rotatability/lockability of ball member  46 , FIGS. 2C and 2D illustrate swivel assembly  40  with the top plate member  44   a  in a “lifted” position and in a “compressed” position, respectively. 
     In the later regard, and as noted above in relation to the embodiment of FIG. 1, a locking member  68  may be provided to apply a force to the top plate member  44   a  to lock-in a desired linear and angular disposition of the carrier assembly  20  shown in FIG.  1 . For such purposes, rotatable ball member  46  includes four slits  52  which extend from aperture  47  through a top portion of the ball member  46  to define four slightly separated upper sections. Of importance, slits  52  extend through only a portion of the rotatable ball member  46 . Consequently, and as shown by FIG. 2D, upon the application of a force to the top surface of the top plate member  44   a  (e.g., by the locking member  68  as described above), the beveled surface  41   a  of the top plate member  44   a  will act to apply on inward force about a top end of the ball member  46  so as to urge the four upper sections thereof inwards. As such, when carrier assembly  20  is positioned within the opening  42  of swivel assembly  40 , the inward motion of the top sections of ball member  46  may serve to lock-in a given linear position of the carrier assembly  20  relative to the swivel assembly  40 . Further, upon the application of downward force to the top plate member  44   a , beveled, annular surface  41   a  of the top plate member  44   a  will act to apply downward forces about the contacted ring portion of ball member  46 , thereby serving to lock-in a given rotational orientation of ball member  46  relative to the top and bottom plate members  44   a ,  44   b . As noted above, when carrier assembly  20  is positioned in the opening  42  of swivel assembly  42  the ability to lock-in a given rotational orientation of ball member  46  allows the carrier assembly  20  to be set in a desired angular position. 
     Reference will now be made to FIGS. 3A-3C which illustrate one embodiment of the carrier assembly  20  shown in FIG.  1 . The illustrated carrier assembly  20  includes an outer support member  24 , an inner shaft member  26  and an extendable, or telescoping, shaft member  28  having a foot-like configuration which defines the first end  22  of the carrier assembly  20 . In the illustrated embodiment, inner shaft member  26  is threaded for driven engagement with an internally threaded surface within telescoping support member  28 . In this regard, a ring portion  30  is provided at the top end of the internal shaft  26  and is sized for rotatable positioning in a bushing arrangement defined by top and bottom ring members  32   a ,  32   b . More particularly, the top and bottom ring members  32   a ,  32   b  may be interconnected about their annular peripheries so as to capture the ring portion  30  of the internal shaft member  26 , and the adjoined rings  32   a ,  32   b  may be secured within a top end  34  of the outer tube member  24 . Such an arrangement axially fixes internal shaft member  26  relative to the outer support member  24 , but allows the internal shaft member  26  to be rotated relative to the outer support member  24 , e.g., via driven engagement by an accessory tool with a hex-end  36  provided at the top end of the internal shaft member  26 . 
     As noted, telescoping support member  28  may be provided with an internally threaded surface for threaded engagement with the inner shaft member  26 . Further, telescoping support member  28  may include an outer groove  38  extending along the length of the telescoping support member  28 . Such groove  38  is provided to co-act with a restraining member  39  projecting from the outer support member  24 . More particularly, when outer support member  24  is in a locked position as described above, restraining member  39  acts to restrain telescoping support member  28  from rotation relative to outer support member  24  upon driven rotation of inner shaft  24 . As such, upon driven rotation of inner shaft member  26 , the telescoping support member  28 , and an implantable actuator  80  interconnected to the footed first end  22  thereof, may be selectively advanced/retracted relative to the outer support member  24  and inner shaft member  26 . 
     Referring now to FIGS. 1,  4  and  5 , interconnection and use of the various components in one application of the described embodiment will be reviewed. Initially, and as shown in FIG. 5, an opening  100  in the mastoid process of a patient&#39;s skull may be defined by drilling or other appropriate process. The opening  100  should be of size sufficient to accommodate insertion of a cylindrical barrel portion  64  of the mounting apparatus  62  therethrough. In this regard, FIG. 1 illustrates a mounting assembly  60  for which skull attachment of the mounting apparatus  62  is achieved via the use of attachment devices  70  inserted through apertures  65  provided in radiating mounting legs  63  at the top end of the mounting apparatus  62 . In an alternate embodiment, as shown in FIGS. 4 and 5, the cylindrical barrel portion  64  may be provided with external threads  67  for threaded engagement with a tapped bore portion defined within the opening  100  of a patient&#39;s skull. 
     After securement of the mounting apparatus  62  to a patient s skull, various components of the positioning embodiment  10 , together with an interconnected actuator  80 , may be positioned through the mounting apparatus  62 . In this regard, interconnection of the various components of the positioning assembly  10 , as well as interconnection of the positioning assembly  10  to actuator  80 , may be completed in conjunction with an implant procedure, or alternatively, may be at least partially completed as part of a production/assembly operation prior to shipment. In either case, before positioning within the mounting apparatus  62 , footed first end  22  of telescoping support member  28  of the carrier assembly  20  may be slidably disposed within a channel  88  provided at the top end of actuator  80  a body portion  84 , and swivel assembly  40  may be positioned as a unit about the outer support member  24  of the carrier assembly  20 . In the later regard, and as noted above, the opening  42  defined through swivel assembly  40  may be sized for slidable friction fit with the outside surface of the support member  24  so as to allow for slidable relative positioning between the two, as well as a degree of retention that restricts swivel assembly  40  from simply sliding off the carrier assembly  20 . 
     In positioning the interconnected positioning assembly  10  and actuator  80  within the mounting apparatus  62 , it may be noted that tab-like extensions of the top and bottom plate members  44   a ,  44   b  of the swivel assembly  40 , as well as rectangular portions of the footed first end  22  and actuator  80 , as well as a signal transmission cable  86  comprising actuator  80 , may all be aligned relative to a complimentary opening  69  provided along one side of the barrel portion  64  of the mounting apparatus  62 . The interconnected positioning assembly  10  and actuator  80  may then be linearly advanced through the barrel portion  64  of mounting apparatus  62  until the bottom plate member  44   b  of swivel assembly  40  supportably engages the bottom end plate  66  of the mounting apparatus  62 . Then, the locking ring  68  may be located in the top end of the barrel portion  64 , but not yet tightened against swivel assembly  40 . The positioning apparatus  10  is now disposed for selective positioning of actuator  80 . 
     In particular, an accessory tool  200  may be inserted through an aperture in locking ring  68  to engage the hex-end  36  of the internal shaft member  26  of carrier assembly  20 . Using the accessary tool  200  the hearing aid actuator  80  may be selectively advanced/retracted into a preliminarily desired depth position via slidable advancement/retraction of the outer support member  24  of the carrier assembly  20  within the opening  42  of the swivel assembly  40 . Further, the angular orientation of the actuator  80  may be selectively adjusted via use of the accessory tool  200  to effect pivotal movement of the carrier assembly  20  and rotation of ball member  46  relative to the top and bottom plate members  44   a ,  44   b  of the swivel assembly  40 . 
     In this regard, where actuator  80  comprises an electromechanical transducer (e.g. as shown in FIGS. 1,  4  and  5 ), a probe tip  82  of the actuator  80  may be pivoted into a position where it is directed towards a desired contact location  120  on the incus bone  110 . Further in this regard, prior to insertion of the positioning apparatus  10  through mounting apparatus  60 , a small hole may be defined at the desired contact location  120  on the surface of the incus  110  (e.g., via use of a laser guide arrangement). It should be noted that the contact location may be defined on other ossicular bones or even perhaps the oval window. 
     When the probe tip  82  of the electromechanical transducer actuator  80  is angularly directed towards the desired contact location  120 , the locking ring  68  may be further advanced within the barrel portion  64  of the mounting apparatus  60  so as lock in the set angular orientation and depth setting of the carrier assembly  20 . Then, to achieve precise positioning of the probe tip  82  a further accessory tool (not shown) may be inserted through the aperture of the mounting/locking ring  68  to natingly engage the hex-end  36  of the internal shaft member  26  of the carrier assembly  20  for driven rotation thereof. In this regard, it should be appreciated that the threading provided on the internal shaft member  26  and telescoping shaft member  28  may be defined so that, for a given amount of driven rotation of the hex-end  36 , a corresponding predetermined desire of linear travel by the first end  22  of the telescoping shaft member  28  will be affected (e.g., ¼ mm travel for each complete rotation). As such, after the probe tip  82  has been advanced into initial contact with the incus  110 , a predetermined degree of loading may be selectively established by driven rotation of hex-end  36 , a predetermined number of revolutions. As will be appreciated, the ability to achieve precise positioning, and loading of an actuator  80  relative to the ossicular chain, yields enhanced acoustic signal transmission and overall improved hearing aid performance. After positioning of the actuator  80 , placement of and connections between other implanted components of a given hearing aid system may be completed prior to system testing and surgical sew-up. 
     The description provided above is solely for purposes of facilitating an understanding of one embodiment of the present invention. Additional embodiments will be apparent to those skilled in the art. For example, while the embodiment described may employ an electromechanical transducer actuator  80 , aspects of the present invention are also employed for positioning other types of implantable hearing aid actuators. Such alternative applications as well as modifications and adaptations of the described embodiment are intended to be within the scope of the present invention as defined by the claims which follow.