Abstract:
A hearing aid system comprised of a housing configured for subcutaneous implantation having a portion configured to extend percutaneously into a patient&#39;s outer ear canal. The percutaneous portion is configured to functionally mate with a transducer capable of being readily exchanged via said outer ear canal.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to hearing aid systems and more particularly to a system including an implantable housing configured to accommodate a transducer in a manner enabling the transducer to be readily exchanged, or replaced, via a patient&#39;s outer ear canal. 
       BACKGROUND OF THE INVENTION 
       [0002]    U.S. patent application Ser. No. 10/702,565 filed on Nov. 5, 2003, which is incorporated herein by reference, describes a hearing aid system including an implant configured for subcutaneous placement in a recess formed between a patient&#39;s retro-auricular space and outer ear canal. The implant is described as comprising a case containing an antenna, electronic circuitry, and a transducer. The transducer functions to convert electrical signals supplied from the implant electronic circuitry into sound energy for projection into the patient&#39;s ear canal. 
         [0003]    U.S. patent application Ser. No. 10/821,383 filed on Apr. 9, 2004, which is incorporated herein by reference, describes an implantable percutaneous device, and method of implantation, especially configured to promote soft tissue ingrowth for creating an infection resistant barrier and for anchoring the implanted device in place. 
         [0004]    PCT application PCT/US2004/041596, filed on 10 Dec. 2004, which is incorporated herein by reference, describes a surgical instrument set and procedure for implanting a hearing aid housing so as to locate a transducer proximate to a patient&#39;s outer ear canal. In a preferred embodiment, the transducer is mounted in a housing stud which projects through a percutaneous hole opening into said outer ear canal. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention is directed to a hearing aid system comprised of a housing configured for subcutaneous implantation and having a portion configured to extend percutaneously into a patient&#39;s outer ear canal. The percutaneous portion is configured to functionally mate with a transducer module capable of being readily exchanged via said outer ear canal. 
         [0006]    In one preferred embodiment of the invention, the housing defines a cavity opening into the patient&#39;s outer ear canal configured to accommodate a transducer module adapted to be inserted into and withdrawn from the cavity. 
         [0007]    In one preferred embodiment, the transducer module carries one or more terminals configured to electrically contact mating terminals on the housing when the transducer is properly seated in the cavity. In an alternative embodiment, the transducer module carries an electric coil configured to inductively couple to an electric coil in the housing when the transducer module is properly seated in the cavity. 
         [0008]    An exchangeable transducer module in accordance with the invention is comprised of at least one electrically driven speaker for directing sound energy into said outer ear canal and/or at least one microphone responsive to acoustic energy in the outer ear canal for generating an electric signal to drive another device, e.g., a cochlear implant. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0009]      FIG. 1  is a side view schematically showing a subcutaneously implanted housing having a portion, or stud, extending percutaneously into a patient&#39;s outer ear canal; 
           [0010]      FIG. 2  is an enlarged cross sectional view taken through the housing of  FIG. 1  showing a cavity in the housing stud and a transducer module configured for insertion into and removal from the cavity; 
           [0011]      FIG. 3  is a representative isometric view showing electric terminals on the transducer module configured to contact mating terminals on the housing when the transducer module is seated in the cavity; 
           [0012]      FIG. 4  is a sectional view similar to  FIG. 2  but showing the transducer module partially inserted into the housing cavity with the assistance of a tool having a pair of tines; 
           [0013]      FIG. 5  is a sectional view taken substantially along the plane  5 - 5  of  FIG. 4 ; 
           [0014]      FIG. 6  is a sectional view taken substantially along the plane  6 - 6  of  FIG. 5 ; and 
           [0015]      FIG. 7  is a sectional view of an alternative embodiment in which the housing and exchangeable transducer module are inductively coupled. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Attention is initially directed to  FIG. 1  which illustrates a hearing aid system housing  10  implanted primarily in a patient&#39;s subcutaneous tissue  12 . The housing comprises a body portion  13  and a stud  14  projecting from the body portion percutaneously through skin tissue  16  into the patient&#39;s outer ear canal  18 . A housing similar to that depicted in  FIG. 1  is described in aforementioned patent application Ser. No. 10/821,383. The housing  10  includes a longitudinally extending body portion surface  21 , a laterally oriented shoulder surface  22 , and a longitudinally extending stud surface  23 . A layer of porous material  24  is preferably affixed to the longitudinal body portion surface  21 , the longitudinal stud surface  23 , and the lateral shoulder surface  22  for promoting healthy tissue ingrowth to form a bacteria resistant barrier. As described in said application Ser. No. 10/821,383, the porous layer  24  is preferably formed by a mesh of intersecting fibers of a suitable biocompatible material such as a metal, e.g., titanium, nitinol, silver, or stainless steel or a polymeric material, e.g., polyolefins, Teflon, nylon, Dacron, or silicone. The mesh is preferably formed by cross winding the fibers in multiple layers to define a porosity conducive to promoting tissue ingrowth, e.g., with pore sizes within a range of 50 to 200 microns and having a porosity of 60 to 95%. Also, it is generally desirable to apply a coating containing one or more antimicrobial and/or anti-inflammatory agents on the housing exterior surface and/or porous layer to promote tissue healing and/or resist infection and inflammation. Suitable agents are known in the literature and include, for example, antibiotics, silver compounds, and steroid based agents. 
         [0017]    The aforementioned application PCT/US2004/041596 describes a preferred surgical instrument set and procedure for implanting the housing  10  with the stud  14  extending through a percutaneous hole  26  in tissue  16  into the outer ear canal  18 . The preferred housing described in said PCT/US2004/041596 houses a power supply and electronic circuitry for driving an electroacoustic transducer mounted in the stud for projecting sound energy directly into the patient&#39;s outer ear canal. 
         [0018]    The present invention is directed to an enhanced hearing aid system in which a percutaneously extending portion of an implanted housing, i.e., stud portion, is configured for detachably mounting a transducer module which can be readily exchanged via the patient&#39;s outer ear canal. The ability to exchange the transducer module via the outer ear canal without disturbing the implanted housing considerably enhances the reliability of the hearing aid system and permits system performance to be upgraded as improved transducers become available. The teachings of the present invention are applicable to systems in which the transducer module carries at least one electrically driven sound generator, e.g., speaker, for directing sound energy into the outer ear canal and/or at least one microphone, for responding to acoustic energy in the outer ear canal for generating a representative electric signal for driving another device, e.g., a speaker or cochlear implant. 
         [0019]    Attention is now directed to  FIGS. 2-6  which illustrate a first preferred embodiment of the present invention.  FIG. 2  is a partial cross section of the housing  10  showing the subcutaneously implanted body portion  13  and the percutaneously extending stud  14 . Note that the stud  14  comprises a peripheral wall  30  which surrounds a cavity  32  bounded by an open cavity entrance  34  and a cavity floor  36 . The periphery of cavity  32  can be shaped in a variety of manners, e.g., square, hexagonal, etc., but unless otherwise stated, it will be assumed hereinafter that the cavity is cylindrical. The cavity  32  is intended to accommodate a similarly shaped transducer module  40  which is configured for easy insertion into and withdrawal from the cavity, as represented by the two-headed arrow  42 . The transducer module  40  is comprised of one or more transducer elements, e.g., one or more speakers and/or microphones, and electronic circuitry  43 , mounted within a transducer module body  44 . A compliant liner  46 , e.g., silicone, is preferably mounted in the cavity  32  attached to the inner surface  47  of peripheral wall  30  to frictionally engage and closely seal against the outer surface  48  of the transducer module body  44 . 
         [0020]    The transducer module body  44  includes a bottom wall  54  carrying one or more externally accessible electric terminals  56 ,  57  which connect through the bottom wall to transducer circuitry (not shown) housed within the body  44 . The transducer terminals  56 ,  57  are located so as electrically contact fixed terminals, e.g.,  58 ,  59 , mounted on the cavity floor  36 . The terminals  58 ,  59  connect through the floor  36  to electronic circuitry  60  mounted within compartment  61  of housing body portion  13 . 
         [0021]    In the embodiment shown in  FIGS. 2 and 3 , the transducer body  44  is configured to slide into cavity  32  to seat transducer terminals  56 ,  57  against fixed terminals  58 ,  59 . It is recognized that in alternative configurations, not shown, the transducer module body  44  and cavity  32  can be differently configured, e.g., with mating threads, to allow the body  44  to be rotated into the cavity  32  to seat transducer terminals  56 ,  57  against fixed terminals  58 ,  59 . 
         [0022]    In order to facilitate the insertion and withdrawal of the transducer body  44  relative to the cavity  32 , it is preferable to provide an annular slot  62  in the outer surface  48  of body  44  and an annular slot  63  in the outer surface  23  of stud wall  30 . These annular slots can be used in conjunction with a preferred dual tine tool  66  ( FIGS. 4-6 ) configured to be inserted by a technician into the patient&#39;s outer ear canal for inserting the transducer body  44  into the cavity  32  or extracting the body from the cavity. 
         [0023]    More particularly, the tool  66  ( FIGS. 4-6 ) is comprised of a first, or outer, member  70  having a U-shaped tine  72  on one end and a handle  74  on the other end and a second, or inner, member  76  having a U-shaped tine  78  and a handle  80  on opposite ends. The first and second members are hinged around pivot point  82  so that when handles  74  and  80  are squeezed by the technician, tines  72  and  78  move toward one another. Conversely, when handles  74  and  80  are moved apart, tines  72  and  78  move apart. 
         [0024]    In use, a technician will, via the patient&#39;s outer ear canal, engage outer tine  72  in slot  62  and inner tine  78  in slot  63 . Then by separating handles  74  and  80 , the transducer module body  44  will move relative to stud wall  30  to extract the body from the cavity  32 . The technician can then replace the extracted body  44  by placing a new transducer module at the cavity entrance  34  and engaging tines  72  and  78  with slots  62  and  63 , respectively. By then squeezing the handles  74 ,  80 , the new transducer module can be forced into the cavity  32  to cause transducer terminals  56 ,  57  to electrically contact fixed housing terminals  58 ,  59 . 
         [0025]    Attention is now directed to  FIG. 7  which shows an alternative to the embodiment illustrated in  FIGS. 2-6 . Whereas the embodiment of  FIGS. 2-6  electrically couples transducer  40  to electronic circuitry  60  via contacting terminals  56 ,  57  and  58 ,  59 , the embodiment of  FIG. 7  instead relies on inductive coupling. More particularly, the transducer module  40 A in  FIG. 7  includes at least one electric coil  90  mounted in transducer module body  44 A. Body  44 A is configured for insertion into, and extraction from, cavity  32 A in the same manner as has been previously discussed relative to  FIGS. 2-6 . 
         [0026]    The housing body portion  13 A in  FIG. 7  houses at least one coil  92  preferably mounted in close proximity to the cavity  32 A to inductively couple coils  90  and  92  when the transducer body  44 A is seated in cavity  32 A. The coil  92  is electrically connected to electronic circuitry  60 A in the housing body portion  13 A. The coil  90  is electrically connected to a transducer element, e.g., speaker or microphone, and electronic circuitry  43 A in the transducer module body  44 A. Thus, the inductively coupled coils  90 ,  92  are able to transfer electric signals representative of sound energy between the electronic circuitry  60 A and the transducer element and circuitry  43 A. 
         [0027]    From the foregoing, it should now be understood that the present invention is directed to a system in which an implanted hearing aid is configured to allow the easy replacement of a transducer module via the patient&#39;s outer ear canal. Although only a limited number of embodiments have been described herein, it is recognized that additional variations and modifications may occur to those skilled in the art. For example, alternatives to frictional engagement of the transducer module and the housing could also include threaded attachment means or locking mechanisms, etc.; alternatives to electrical contacts could also include the use of pins, etc. Additionally, alternative geometries can be employed to optimize inductive coupling of the coils  90 ,  92 . Yet additional variations and modifications which are consistent with the spirit and teachings of the invention and which are intended to fall within the scope of the appended claims are also likely to occur to those skilled in the art.