Abstract:
A non-communicative lumen for electrode assemblies of medical implants, in particular prosthetic hearing implants, is provided by the present invention. The non-communicative lumen prevents the lumen within the cochlea from being able to transport fluids, cells, bacteria, tissue, etc., with the lumen outside the cochlea, and vis versa through the incision or cochleostomy. The lumen may have a cavity or slit that receives a stylet during insertion of the electrode assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 11/268,592; filed on Nov. 8, 2005, which is hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to electrode assemblies and, more particularly, to a non-communicative lumen for an electrode assembly. 
     2. Related Art 
     There are a variety of medical implants which deliver electrical stimulation to a patient or recipient (“recipient” herein) for a variety of therapeutic benefits. For example, the hair cells of the cochlea of a normal healthy ear convert acoustic signals into nerve impulses. People who are profoundly deaf due to the absence or destruction of cochlea hair cells are unable to derive suitable benefit from conventional hearing aid systems. Prosthetic hearing implant systems have been developed to provide such persons with the ability to perceive sound. Prosthetic hearing implant systems bypass the hair cells in the cochlea to directly deliver electrical stimulation to auditory nerve fibers, thereby allowing the brain to perceive a hearing sensation resembling the natural hearing sensation. 
     The electrodes implemented in stimulating medical implants vary according to the device and tissue which is to be stimulated. For example, the cochlea is tonotopically mapped and partitioned into regions, with each region being responsive to stimulus signals in a particular frequency range. To accommodate this property of the cochlea, prosthetic hearing implant systems typically include an array of electrodes each constructed and arranged to deliver an appropriate stimulating signal to a particular region of the cochlea. 
     To achieve an optimal electrode position close to the inside wall of the cochlea, the electrode assembly should assume this desired position upon or immediately following implantation into the cochlea. It is also desirable that the electrode assembly be shaped such that the insertion process causes minimal trauma to the sensitive structures of the cochlea. Usually the electrode assembly is held in a straight configuration at least during the initial stages of the insertion procedure, conforming to the natural shape of the cochlear once implantation is complete. 
     SUMMARY 
     In one aspect of the present invention, an electrode assembly for implantation in a recipient&#39;s cochlear via a cochleostomy is disclosed. The electrode assembly comprises an electrode array and an elongate carrier member having a lumen extending longitudinally through at least a portion thereof, and having a distal end on which said electrode array is disposed. The elongate carrier member comprises a distal intra-cochlear region adapted to be implanted in the cochlear, and having the lumen extending at least partially therethrough; and an incision region, contiguous with the intra-cochlear region, adapted to be partially positioned in the cochlear, wherein the lumen extending therethrough is non-communicative across the cochleostomy. 
     In another aspect of invention, a prosthetic hearing implant system is disclosed. The prosthetic hearing implant system comprises an electrode assembly for implantation in a recipient&#39;s cochlear via a cochleostomy. The electrode assembly comprises an electrode array and an elongate carrier member having a lumen extending longitudinally through at least a portion thereof, and having a distal end on which the electrode array is disposed. The elongate carrier member comprises a distal intra-cochlear region adapted to be implanted in the cochlear, and having the lumen extending at least partially therethrough; and an incision region, contiguous with the intra-cochlear region, adapted to be partially positioned in the cochlear, wherein the lumen extending therethrough is non-communicative across the cochleostomy. 
     In a further aspect of the invention, an electrode assembly for implantation in a recipient&#39;s cochlear via a cochleostomy is disclosed. The electrode assembly comprises: an elongate stylet; an electrode array; and an elongate carrier member having a distal end on which said electrode array is disposed, comprising: a distal intra-cochlear region adapted to be implanted in the cochlear and having a lumen extending at least partially therethrough; and an incision region, contiguous with the intra-cochlear region, adapted to be partially positioned in the cochlear, having a non-communicative extending therethrough; and an elongate cartridge configured to slidingly receive said stylet and said carrier member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention are described herein in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of an implanted prosthetic hearing implant system having a non-communicative lumen in accordance with embodiments of the present invention; 
         FIG. 2A  is a side view of an electrode of assembly in accordance with one embodiment of the present invention; 
         FIG. 2B  is a cross-sectional view of one embodiment of the of the electrode assembly illustrated in  FIG. 2A  taken along section line  2 B- 2 B in  FIG. 2A ; 
         FIG. 2C  is a cross-sectional view of one embodiment of the electrode assembly illustrated in  FIG. 2A  taken along section line  2 C- 2 C in  FIG. 2A ; 
         FIG. 3A  is a side view of an electrode assembly in accordance with one embodiment of the present invention; 
         FIG. 3B  is a cross-section view of one embodiment of the electrode assembly shown in  FIG. 3A , taken along section line  3 B- 3 B in  FIG. 3A ; 
         FIG. 3C  is a cross-section view of an alternative embodiment of the electrode assembly shown in  FIG. 3A , also taken along section line  3 C- 3 C in  FIG. 3A ; 
         FIG. 4  is a side view of an electrode assembly in accordance with one embodiment of the present invention; 
         FIG. 5A  is a side view of an electrode assembly in accordance with one embodiment of the present invention; 
         FIG. 5B  is an enlarged side view of one embodiment of the electrode assembly incision region shown in  FIG. 5A ; 
         FIG. 5C  is a perspective view of one embodiment of the electrode assembly incision region shown in  FIG. 5A ; 
         FIG. 6A  is a side view of an electrode assembly in accordance with one embodiment of the present invention; 
         FIG. 6B  is a perspective view of the incision region of the electrode assembly illustrated in  FIG. 6A ; 
         FIG. 6C  is a cross-sectional view of the incision region of the electrode assembly illustrated in  FIGS. 6A and 6B  taken along section line  6 C- 6 C in  FIG. 6B ; 
         FIG. 6D  is a cross-sectional view of the incision region of the electrode assembly illustrated in  FIGS. 6A and 6B  taken along section line  6 D- 6 D in  FIG. 6B ; 
         FIG. 7  is a side view of an electrode assembly in accordance with one embodiment of the present invention; 
         FIG. 8A  is a side view of an electrode assembly in accordance with one embodiment of the present invention; 
         FIG. 8B  is a cross-sectional view of the electrode assembly illustrated in  FIG. 8A  taken along section line  8 B- 8 B; 
         FIG. 8C  is a cross-sectional view of the electrode assembly illustrated in  FIG. 8A  taken along section line  8 C- 8 C in  FIG. 8A ; 
         FIG. 9  is a side view of an electrode assembly in accordance with one embodiment of the present invention; 
         FIG. 10  is a perspective view of an electrode assembly in accordance with one embodiment of the present invention; and 
         FIG. 11  is a perspective view of an electrode assembly in accordance with one embodiment of the present invention. 
         FIG. 12A  is a side view of an electrode assembly in accordance with one embodiment of the present invention; 
         FIG. 12B  is a cross-sectional view of the electrode assembly illustrated in  FIG. 12A  taken along section line  12 B- 12 B; and 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the present invention are directed to an implantable elongate carrier member, lead, catheter or the like (collectively and generally referred to as a “carrier member”) with an integrated lumen and a therapeutic device disposed at the distal end of the carrier member. Lumens which pass through an incision made to implant a therapeutic device create a potential pathway for fluids, tissue, cells, bacteria or other organic material which may, for example, damage the therapeutic device or cause infection, disease or other undesirable medical conditions. For example, in the context of a cochlear implant, a carrier member lumen that extends through a cochleostomy may increase the risk of meningitis caused by fluid ingress into the lumen and, ultimately, into the cochlear. 
     Aspects of the present invention provide a carrier member lumen that is non-communicative across the incision to prevent the lumen from serving as a communicative pathway for organic material through the incision. In various embodiments of the present invention, the non-communicative lumen is severed, removed, blocked, diverted or otherwise interrupted in the region of the carrier which transitions through the incision thereby interrupting the pathway for the organic material. 
     Exemplary embodiments of the present invention are further described below in conjunction with an implanted unit of a prosthetic hearing implant system, such as a Contour™, Freedom™, Nucleus™ or Cochlear™ systems commercially available from Cochlear Limited, Australia. Such devices are described in U.S. Pat. Nos. 4,532,930, 6,537,200, 6,565,503, 6,575,894, and 6,697,674, the entire contents and disclosures of which are hereby incorporated by reference herein. It should be understood to those of ordinary skill in the art that embodiments of the present invention may be used in other stimulating medical devices such as neurostimulators, cardiac pacemakers/defibrillators, etc. 
       FIG. 1  is a cut-away view of the relevant components of outer ear  101 , middle ear  102  and inner ear  103 , which are described next below. In a fully functional ear, outer ear  101  comprises an auricle  105  and an ear canal  106 . An acoustic pressure or sound wave  107  is collected by auricle  105  and channeled into and through ear canal  106 . Disposed across the distal end of ear cannel  106  is a tympanic membrane  109  which vibrates in response to acoustic wave  107 . This vibration is coupled to oval window or fenestra ovalis  110  through three bones of middle ear  102 , collectively referred to as the ossicles  111  and comprising the malleus  112 , the incus  113  and the stapes  114 . Bones  112 ,  113  and  114  of middle ear  102  serve to filter and amplify acoustic wave  107 , causing oval window  110  to articulate, or vibrate. Such vibration sets up waves of fluid motion within cochlea  115 . Such fluid motion, in turn, activates tiny hair cells (not shown) that line the inside of cochlea  115 . Activation of the hair cells causes appropriate nerve impulses to be transferred through the spiral ganglion cells and auditory nerve  116  to the brain (not shown), where they are perceived as sound. In deaf persons, there is an absence or destruction of the hair cells. Prosthetic hearing implant  120  is needed to directly stimulate the ganglion cells to provide a hearing sensation to the recipient. 
       FIG. 1  also shows how an implanted prosthetic hearing implant  120  is positioned in relation to outer ear  101 , middle ear  102  and inner ear  103 . Prosthetic hearing implant  120  comprises external component assembly  122  which is directly or indirectly attached to the body of the recipient, and an internal component assembly  124  which is temporarily or permanently implanted in the recipient. External assembly  122  comprises microphone  125  for detecting sound which is outputted to a BTE (Behind-The-Ear) speech processing unit  126  that generates coded signals and are provided to an external transmitter unit  128 , along with power from a power source  129  such as a battery. External transmitter unit  128  comprises an external coil  130  and, preferably, a magnet (not shown) secured directly or indirectly in external coil  130 . Internal components  124  comprise an internal receiver unit  132  having an internal coil (not shown) that receives and transmits power and coded signals from external assembly  122  to a stimulator unit  134  to apply the coded signal along an electrode assembly  140 . Electrode assembly  140  enters cochlea  115  at cochleostomy region  142  and has one or more electrodes  150  is positioned to substantially be aligned with portions of tonotopically-mapped cochlea  115 . Signals generated by stimulator unit  134  are applied by the electrodes  150  of electrode array  144  to cochlea  115 , thereby stimulating the auditory nerve  116 . It should be appreciated that although in the embodiment shown in  FIG. 1  electrodes  150  are arranged in an array  144 , other arrangements are possible. 
       FIGS. 2A through 2C  are side and cross-sectional views, respectively, of one embodiment of electrode assembly  140  illustrated in  FIG. 1 , referred to herein as electrode assembly  200 . Electrode assembly  200  has an elongate carrier member  202  on which an array  144  of electrodes  150  is disposed. Electrode assembly  200  and, hence, carrier member  202 , has a distal end  210  at which electrode array  144  is disposed, and a proximal end  220  which either is connected to, or is proximate to, stimulator unit  134  (not shown in  FIG. 2A ). For ease of description, future reference to a carrier member and an electrode assembly are considered to refer to the other unless otherwise understood from the context or express statements. 
     This illustrative embodiment of electrode assembly  200  comprises three contiguous regions: an intra-cochlear carrier region  204  disposed toward and comprising distal end  210  of electrode assembly  200 , an extra-cochlear carrier region  206  disposed toward and comprising proximal end  220  of electrode assembly  200 , and an incision region  240  interposed between intra-cochlear carrier region  204  and extra-cochlear carrier region  206 . 
     In the exemplary cochlear implant application, the incision made to implant an electrode assembly such as electrode assembly  140  is commonly referred to as a cochleostomy. For example, in the above description referring to  FIG. 1 , the incision in cochlear  115  is referred to as cochleostomy region  142  or, simply, cochleostomy  142 . The location of cochleostomy  142  is schematically represented in  FIG. 2A  by a dashed line. As one of ordinary skill in the art would appreciate, dashed line  142  represents the common general location of the cochleostomy; it does not represent other aspects of the cochleostomy such as, for example, the thickness of the incision. 
     Electrode assembly  200  is configured such that, when implanted, the portion of elongate electrode assembly  200  located in cochlear  115  includes intra-cochlear carrier region  204  and a portion of incision region  240 . As such, the remaining portion of incision region  240  and extra-cochlear carrier region  206  are located external to cochlear  115  when carrier member  200  is implanted. 
     Electrode assembly  200  further comprises a lumen  224  extending through a substantial length of elongate carrier member  202 . Lumen  224  extends through a portion of extra-cochlear carrier region  206  and a portion of intra-cochlear carrier region  204 . In accordance with the teachings of the present invention, at least the section of incision region  240  that extends through cochleostomy  142  is non-communicative. As such, there is no communication of organic material from the portion of the lumen external to cochlear  115  to the portion of the lumen internal to cochlear  115 . Notably, in the embodiment shown in  FIG. 2A , lumen  224  is interrupted or absent in incision region  240 , as shown in  FIG. 2A . This is described in further detail below with reference to  FIGS. 2B and 2C .  FIG. 2B  is a cross-sectional view of carrier member  200  taken along section line  2 B- 2 B through extra-cochlear region  206  as shown in  FIG. 2A ;  FIG. 2C  is a cross-sectional view of carrier member  200  taken along section line  2 C- 2 C through incision region  240  as shown in  FIG. 2A . 
     Carrier member  202  may be further considered to have an upper elongate region  203  and a lower elongate region  205 . As shown in  FIGS. 2A and 2B , intra- and extra-cochlear regions  204  and  206  comprise both upper and lower elongate regions  203  and  205 , while incision region  240  comprises upper elongate region  203  and only a small portion of lower elongate region  205 . Lower elongate region  205  in incision region  240  does not include any portion of lumen  224 . As such, the cross-sectional area of electrode assembly  200  in incision region  240  is less than the cross-sectional area of electrode assembly  200  in extra-cochlear region  206 , and lumen  224  extends through extra- and intra-cochlear regions  206  and  204 , and is absent in incision region  240 . More generally, lumen  224  in region  240  of carrier  200  extending through incision  142  is interrupted to prevent lumen  224  from serving as a communicative pathway for organic material or other undesirable material through the incision. In other words, lumen  224  is a non-communicative lumen due to the absence of lumen  224  in incision region  240 . 
     Lumen  224  is configured to receive a straightening element  230  such as a wire, which is commonly referred to as a stylet in the context of prosthesis hearing implant systems. Regardless of application, straightening elements described herein in connection with various embodiments of the present invention are referred to herein as stylets for ease of reference. Prior to implanting electrode assembly  200 , stylet  230  is inserted into lumen  224  to straighten electrode assembly  200 , which is biased to curl; that is, to have an approximately round shape formed by one or more concentric circles. Thus, in intra-cochlear carrier region  204 , lumen  224  performs a straightening function that holds electrode assembly  200  substantially straight during insertion. While electrode assembly  200  is inserted through cochleostomy  142 , a surgeon biases forward carrier member  202  on stylet  230  to implant carrier member  202 , causing carrier member  202  to curve so as to follow the curvature of cochlear  115 . 
     Carrier member  202  may have a series of one or more optional guide ribs  208  disposed on the surface of extra-cochlear region  206  to facilitate manual control (direct or with an instrument) of carrier member  202  during implantation. In one embodiment, guide ribs  208  extend around a portion of the circumference of carrier member  200  and are raised above the surface of carrier member  202  as shown in  FIG. 2A . As one of ordinary skill in the art would find apparent, guide ribs are not required, and when utilized in various embodiments of the present invention may take on other forms suitable for facilitating manual or instrument control of the carrier member. 
     Carrier member  202  also has a series of one or more optional markers  209  disposed in or on incision region  240  of carrier member  200 . In the embodiment shown in  FIG. 2A , there are three markers  209  embedded in the surface of carrier member  200 . Markers  209  facilitate locating carrier member  200  such that incision region  240  is positioned so as to be partially located within cochlear  115 . As one of ordinary skill in the art would appreciate, markers  209  as well as other markers implemented in other embodiments of the present invention may be any type of device that facilitates visual recognition of the location of the carrier member in a recipient. Such recognition may involve imaging systems in which case one or more of the markers  209  will include features or materials identifiable by such imaging systems. 
     Lumen  224  in extra-cochlear carrier region  206  performs a guiding function rather than a straightening function since carrier member  202  is straight (not pre-curved) in this region of electrode assembly  200 . Such guiding function in lumen  224 , and hence extra-cochlear region  206  of electrode assembly  200 , may provide a point to hold electrode assembly  200  and stylet  230  well away from cochlea  115  and outside the posterior tympanotomy. 
     During the packing of cochleostomy area  142  with temporalis fascia, the fascia presses and hermetically seals against carrier member  202 . Other techniques to seal and hold electrode assembly  202  in cochleostomy region  142  may be used instead of or in addition to packing, such as the use of sutures or split bridge. 
     There are a number of advantages which may be derived from the above embodiments of the present invention. For example, electrode assembly  200  may be inserted and manipulated in a manner that is substantially similar to techniques commonly used to implant a conventional electrode assembly; that is, one having a continuous lumen. Thus no new training is required for surgeons utilizing embodiments of the present invention. Further, the embodiments shown in  FIGS. 2A through 2C  may provide additional benefits over standard electrode assemblies in that the contacting area between carrier member  202  and stylet  230  is reduced. The reduced contact area may, in turn, reduce the dynamic friction between the carrier member and stylet, thereby reducing the force required to remove stylet  230  from carrier member  202 . Also, the reduction in friction may decrease the propensity for stylet  230  to temporarily adhere to carrier member  202  when electrode assembly  200  is installed on and removed from stylet  230 . 
       FIGS. 3A and 3B  illustrate another embodiment of electrode assembly  140  of the present invention, referred to herein as electrode assembly  300 .  FIG. 3A  is a side view of electrode assembly  300  while  FIG. 3B  is a cross-section view of electrode assembly  300  taken along section line  3 B- 3 B in  FIG. 3A . 
     In the embodiment illustrated in  FIGS. 3A-3B , lower elongate region  305  of carrier member  302  is partially removed in incision region  340 . As shown best in  FIG. 3B , the portion of lower elongate region  305  that is not removed defines an upper surface  314  of lumen  324 . That is, lumen  324  is non-communicative in incision region  340  due to the partial removal of lumen  324  in that region. It should be appreciated that the partial removal of lumen  324  sufficient to make lumen  324  non-communicative may vary depending on the particular objectives and applications. For example, in the alternative embodiment illustrated in  FIG. 3C , the remaining portion of lower elongate region  305  defines a side surface  315  of lumen  324 . As such, this embodiment of lumen  324  is also non-communicative in incision region  340  due to the partial removal of lumen  324  in that region. As one of ordinary skill in the art would appreciate, other portions of lower elongate region  305  of carrier member  302  may be removed or otherwise altered to make lumen  324  non-communicative in incision region  340  region. 
       FIG. 4  is a side view of another embodiment of electrode assembly  140  introduced above with reference to  FIG. 1 , referred to herein as electrode assembly  400 . The illustrative embodiment of electrode assembly  400  illustrated in  FIG. 4  comprises three contiguous regions: an intra-cochlear carrier region  404  disposed toward and comprising distal end  410  of electrode array  400 , an extra-cochlear carrier region  406  disposed toward and comprising proximal end  420  of electrode assembly  400 , and an incision region  440  interposed between intra-cochlear carrier region  404  and extra-cochlear carrier region  406 . 
     In addition, electrode assembly  400  is formed of two integrated or unitary elongate portions: an upper elongate portion  403  and a lower elongate portion  405 . As shown in  FIG. 4 , lower elongate portion  405  of carrier member  402  is removed from extra-cochlear carrier region  404  and incision region  440 . As such, lumen  424  extend through a portion of intra-cochlear region  404  and neither cochleostomy region  142  nor extra-cochlear carrier region  406 . Lumen  424  has a proximal opening  416  configured to receive stylet  430 , as shown in  FIG. 4 . Thus, there is no communicative path through incision region  142  via lumen  424 . During the packing of cochleostomy area  142 , the fascia presses and hermetically seals against electrode assembly  400 . 
     It is noted that intra-cochlear carrier region  404  performs guiding and straightening functions toward distal end  410  which allows electrode assembly  400  to be pushed forward on stylet  430 . This may improve the precision with which electrode assembly  400  is controlled during implantation since the pushing of stylet  430  may occur at a location closer to distal end  410  of electrode assembly  400 . 
     Since there is no carrier or lumen in cochleostomy region  142 , a weak point may be created in electrode assembly  400 . The weak point may lead to undesirable bending or kinking should electrode assembly  400  meet resistance during implantation. Therefore, in certain embodiments of electrode assembly  400  carrier member  402  is strengthened in cochleostomy region  440 . 
     As noted above with reference to the embodiments illustrated in  FIGS. 2A-2C , the contacting area between carrier member  402  and stylet  430  is reduced. This reduced contact area may, in turn, reduce the dynamic friction between the carrier member and stylet, thereby reducing the force required to remove stylet  430  from carrier member  402 . Also as noted above, the reduction in friction may decrease the propensity for stylet  430  to temporarily adhere to carrier member  402  when electrode assembly  400  is installed on and removed from stylet  430 . 
       FIGS. 5A ,  5 B and  5 C illustrate another embodiment of an electrode assembly  140  having a non-communicative lumen in accordance with the teachings of the present invention, referred to herein as electrode assembly  500 .  FIG. 5A  is a side view of electrode assembly  500 . Electrode assembly  500  has a carrier member  502  formed of an upper elongate portion  503  and a lower elongate portion  505 . Electrode assembly  500  comprises three contiguous regions: an intra-cochlear carrier region  504  disposed toward and comprising distal end  510  of electrode array  500 , an extra-cochlear carrier region  506  disposed toward and comprising proximal end  520  of electrode assembly  500 , and an incision region  540  interposed between intra-cochlear carrier region  504  and extra-cochlear carrier region  506 .  FIG. 5B  is an enlarged side view and  FIG. 5C  is a perspective view of incision carrier region  540  of  FIG. 5A . 
     Lumen  524  extends through at least a portion of intra-cochlear region  504 , incision region  540  and extra-cochlear carrier region  506 . In  FIG. 5A  a stylet  530  is shown partially inserted into lumen  524 . 
     A series of one or more radial slots  550  are formed in lower elongate portion  505  of carrier member  502  in incision region  142  of electrode assembly  500 . In the embodiment shown in  FIG. 5A , there are a plurality of radial slots  550  and a plurality of radial support ribs  552 . Radial slots  550  interrupt lumen  524 , resulting in a lumen which is non-communicative at a number of locations in incision region  540 . That is, radial slots  550  ensure that there is no continuous pathway for organic material or other undesirable elements to travel through lumen  524  through cochleostomy  142 . 
     Radial support ribs  552  provide further guiding and straightening functions that assist in constraining stylet  530  during insertion and withdrawal. Radial support ribs  552  also allow markers  209  to extend up to approximately 270° degrees around the circumference of electrode assembly  500 . 
     In one embodiment, radial support ribs  552  are approximately 0.2 to 1 mm in length, and radial slots  550  are approximately 0.2 mm to 1 mm in length. In one particular embodiment, radial extensions  552  are 0.5 mm in length and radial slots  550  are 0.5 mm. In the illustrative embodiment, radial slots  550  have similar dimensions while radial extensions  552  have similar dimensions. It should be appreciated, however, that in alternative embodiments, a different quantity of radial slots  550  have dimensions which are the same or different than the dimensions of radial extensions  552  and those illustrated in  FIGS. 5A-5C  may be implemented. It should also be appreciated that in those embodiments in which there is a plurality of radial slots  550  and radial support ribs  552 , the dimensions of such radial slots and support ribs may vary along the length of incision region  540 . 
       FIGS. 6A through 6D  illustrate another embodiment of an electrode assembly  140  having a non-communicative lumen in accordance with the teachings of the present invention, referred to herein as electrode assembly  600 .  FIG. 6A  is a side view of electrode assembly  600 . Electrode assembly  600  has a carrier member  602  formed of an upper elongate portion  603  and a lower elongate portion  605 . Electrode assembly  600  comprises three contiguous regions: an intra-cochlear carrier region  604  disposed toward and comprising distal end  610  of electrode array  600 , an extra-cochlear carrier region  606  disposed toward and comprising proximal end  620  of electrode assembly  600 , and an incision region  640  interposed between intra-cochlear carrier region  604  and extra-cochlear carrier region  606 .  FIG. 6B  is a perspective view, and  FIGS. 6C and 6D  are cross-sectional views taken along section lines  6 C- 6 C and  6 D- 6 D, respectively, of incision carrier region  640 , as shown in  FIG. 6B . 
     Lumen  624  extends through at least a portion of intra-cochlear region  604 , incision region  640  and extra-cochlear carrier region  606 . A stylet  630  is shown positioned within lumen  624 . In incision region  640 , lower elongate region  605  comprises a series of sequentially alternating lateral support ribs  650 . That is, in one portion of incision region  640 , a lateral support rib  650  laterally supports stylet  630  from one side of carrier member  602 , and in a linearly adjacent portion of incision region  640 , a neighboring lateral support rib  650  laterally supports stylet  630  from the laterally-opposing side of carrier member  602 . 
     This is illustrated in  FIGS. 6C and 6D  which are cross-sectional views of incision region  640  taken along section lines  6 C- 6 C and  6 D- 6 D in  FIG. 6B . In particular,  FIGS. 6C and 6D  are cross-sectional views showing linearly adjacent lateral support ribs  650  in incision region  640 . As shown in  FIGS. 6B and 6C , lateral support rib  650  at section line  6 C- 6 C laterally supports stylet  630  on one side of the stylet. The laterally opposite side of lower elongate region  605  is a void  656 . Conversely, as shown in  FIGS. 6B and 6D , lateral support rib  650  at section line  6 D- 6 D laterally supports stylet  630  on the opposing side of the stylet. The other side of lower elongate region  605  is a void  656 . Thus, stylet  630  is supported in lumen  624  along incision region  640  by alternating lateral support ribs  650 . The alternating design creates a lumen  624  having a non-communicative pathway in incision region  640  of electrode assembly  600 . 
     Lateral support ribs  650  provide further guiding and straightening functions that assist in constraining stylet  630  during withdrawal. Lateral support ribs  650  also allow markers  209  to extend up to approximately 270° degrees around the circumference of electrode assembly  600  in incision region  640 . 
       FIG. 7  is a side view of another embodiment of electrode assembly  140  having a non-communicative lumen in accordance with the teachings of the present invention, referred to herein as electrode assembly  700 . Electrode assembly  700  has a carrier member  702  formed of an upper elongate portion  703  and a lower elongate portion  705 . Electrode assembly  700  comprises three contiguous regions: an intra-cochlear carrier region  704  disposed toward and comprising distal end  710  of electrode array  700 , an extra-cochlear carrier region  706  disposed toward and comprising proximal end  720  of electrode assembly  700 , and an incision region  740  interposed between intra-cochlear carrier region  704  and extra-cochlear carrier region  706 . 
     Lumen  724  extends through at least a portion of intra-cochlear region  704 , incision region  740  and extra-cochlear carrier region  706 . A stylet  730  is shown positioned within lumen  724 . The portion of lumen  724  extending through intra-cochlear region  704  performs a straightening and guiding function while the portion of lumen  724  extending through extra-cochlear region  706  performs a guiding function. 
     A section  788  of lower elongate portion  705  of carrier member  702  in incision region  740  is removable. Upon removal of removable section  788  from lower elongate portion  705 , lumen  724  will be interrupted in incision region  740 , resulting in a non-communicative lumen  724  across incision  142 . 
     In one embodiment, removable section  788  of lower elongate portion  705  is formed from a dissolvable/resorable material. For example, in certain embodiments, removable section  788  is formed of a resorable polymer such as polylactic acid (PLA) and polyglycolic acid (PGA). Other biodegradable or dissolvable materials or combinations thereof may be used as well. After insertion of electrode assembly  700  and packing of cochleostomy  142 , the resorable polymer is absorbed by the recipient, resulting in a non-communicative lumen  124  across incision  142 . Advantageously, removable section  788  provides for a non-communicative lumen  724  in incision region  740  when electrode assembly  700  is implanted while also enhancing the strength of electrode assembly  700  during implantation. 
     Alternatively, section  788  is a detachable section of lower elongate portion  705  in an alternative embodiment of the present invention. In such alternative embodiments, section  788  is removed manually or otherwise prior to implantation or packing of cochleostomy area  142 . In one embodiment, section  788  is configured to be easily removable with forceps. 
       FIG. 8A  is a side view of another embodiment of electrode assembly  140  having a non-communicative lumen in accordance with the teachings of the present invention, referred to herein as electrode assembly  800 . Electrode assembly  800  has a carrier member  802  formed of an upper elongate portion  803  and a lower elongate portion  805 . Electrode assembly  800  comprises three contiguous regions: an intra-cochlear carrier region  804  disposed toward and comprising distal end  810  of electrode array  800 , an extra-cochlear carrier region  806  disposed toward and comprising proximal end  820  of electrode assembly  800 , and an incision region  840  interposed between intra-cochlear carrier region  804  and extra-cochlear carrier region  806 . 
     Lumen  824  extends through at least a portion of intra-cochlear region  804 , incision region  840  and extra-cochlear carrier region  806 . In this embodiment, lumen  824  is a collapsible lumen that expands in response to an insertion force applied to stylet  830 .  FIG. 8A  is a cross-sectional view of carrier member  802  taken along section line  8 B- 8 B of  FIG. 8A . As shown in  FIGS. 8A and 8B , collapsible lumen  824  is forced open and extends around the circumference of the inserted portion of stylet  830 . 
       FIG. 8C  is a cross-sectional view of carrier member  802  taken along section line  8 C- 8 C of  FIG. 8A . As shown in  FIG. 8A , stylet  830  does not extend through lumen  824  to section line  8 C- 8 C. As such, lumen  824  is collapsed at section line  8 C- 8 C, as shown in  FIG. 8C . Thus, lumen  824  expands and collapses in response to the introduction and presence of stylet  830 . Prior to implantation, stylet  830  is inserted into collapsed lumen  824 , causing lumen  824  to expand around stylet  830 . Then, electrode assembly  800  is implanted during which stylet  830  is removed from lumen  824 . As stylet  830  is removed, lumen  824  collapses once again, resulting in a non-communicative lumen. In such embodiments, lumen  824  is non-communicative along its entire length as compared to certain other embodiments of the present invention in which lumen  824  is non-communicative only in incision region  142 . 
     In addition, packing lumen  824  will further compress and creates a seal and a non-communicative path in lumen  824 . During the packing of cochleostomy  142 , the fascia presses and hermetically seals against electrode assembly  800 . Lumen  824  may also be plugged with a plugging material (not shown) once stylet  830  is fully removed. As one of ordinary skill in the art would appreciate, in such embodiments carrier member  802  performs guiding and straightening functions throughout its entire length. 
       FIG. 9  is a side view of another embodiment of electrode assembly  140  having a non-communicative lumen in accordance with the teachings of the present invention, referred to herein as electrode assembly  900 . Electrode assembly  900  has a carrier member  902  formed of an upper elongate portion  903  and a lower elongate portion  905 . Electrode assembly  900  comprises three contiguous regions: an intra-cochlear carrier region  904  disposed toward and comprising distal end  910  of electrode array  900 , an extra-cochlear carrier region  906  disposed toward and comprising proximal end  920  of electrode assembly  900 , and an incision region  940  interposed between intra-cochlear carrier region  904  and extra-cochlear carrier region  906 . 
     Lumen  924  extends through at least a portion of intra-cochlear region  904 , incision region  940  and extra-cochlear carrier region  906 . In this embodiment, lumen  924  is interrupted along two sections  950 A and  950 B in incision region  940 . Section  950 A and  950 B are divided by a support rib  952 . In the illustrative embodiment, such interruption is attained by the absence of lower elongate portion  905  of carrier member  902 . Advantageously, this allows electrode assembly  900  to be positioned at different depths to account for the various depth requirements of electrode assembly  900 . 
       FIGS. 10 and 11  are perspective views of two embodiments of an electrode assembly  140  having a non-communicative lumen in accordance with the teachings of the present invention, referred to herein as electrode assembly  1000  and  1100 , respectively. Electrode assemblies  1000  and  1100  each comprises three contiguous regions similar to those described above in connection with other embodiments of the present invention. In  FIGS. 10 and 11  only a portion of incision region  1040  and  1140 , respectively, are shown for clarity. 
     Electrode assembly  1000  has a carrier member  1002  formed of an upper elongate portion  1003  and a lower elongate portion  1005 . Similarly, electrode assembly  1100  has a carrier member  1102  formed of an upper elongate portion  1103  and a lower elongate portion  1105 . 
     Carrier members  1002  and  1102  each have a raised surface  1007  and  1107 , respectively, formed on upper elongate portion  1003  and  1103 , in incision region  1004  and  1104 , respectively. Raised surfaces  1007  and  1107  are provided in addition or alternatively to markers  209  described above in connection with other embodiments of the present invention. A removable cartridge  1080  and  1180  travels parallel with the longitudinal axis of the respective carrier members  1002  and  1102  on rails  1070 ,  1170  formed in the upper elongate portions  1005 ,  1105 , respectively. 
     In both embodiments, stylets  1030 ,  1130  extend through the respective lumen  1024 ,  1124  that is provided in extra-cochlear region (not shown) and intra-cochlear region  1004 ,  1104 , respectively. In incision regions  1040  and  1140 , lower elongate portions  1005  and  1105  are at least partially absent to provide a non-communicative lumen in incision regions  1040  and  1140 . In the embodiment shown in  FIG. 10 , lower elongate portion  1005  is completely absent while in the embodiment shown in  FIG. 11 , lower elongate portion  1105  is partially absent. 
     In both embodiments, upper elongate portions  1005  and  1105  form a rail adapted to be slidingly received by slots  1082  and  1182 , respectively, of their respective cartridge  1080  and  1180 . Removal cartilages  1080  and  1180  may slide or fit over rails  1070  and  1170  as shown in  FIGS. 10 and 11 . Further, removal cartilages  1080  and  1180  may be connected to the respective stylet  1030  and  1130  to enable the surgeon to guide the stylet out of the respective lumen  1024  and  1124 . Removal cartilages  1080  and  1180  may enhance the strength of electrode assemblies  1000  and  1100  and provide straightening and guiding functions. 
     It should be appreciated that the rails in the above embodiments are optional and that cartridge may be part of the insertion tool. An example of such an embodiment is illustrated in  FIGS. 12A and 12B .  FIGS. 12A and 12B  are side and cross-sectional views, respectively, of one embodiment of electrode assembly  140  illustrated in  FIG. 1 . referred to herein as electrode assembly  1200 . Electrode assembly  1200  has an elongate carrier member  1202  on which an array  144  of electrodes  150  is disposed. Electrode assembly  1200  and, hence, carrier member  1202 , has a distal end  1210  at which electrode array  144  is disposed, and a proximal end  1220  which either is connected to, or is proximate to, stimulator unit  134  (not shown in  FIGS. 12A and 12B ). 
     This illustrative embodiment of electrode assembly  1200  comprises three contiguous regions: an intra-cochlear carrier region  1204  disposed toward and comprising distal end  1210  of electrode assembly  1200 , an extra-cochlear carrier region  1206  disposed toward and comprising proximal end  1220  of electrode assembly  1200 , and an incision region  1240  interposed between intra-cochlear carrier region  1204  and extra-cochlear carrier region  1206 . 
     Carrier member  1202  is formed of an upper elongate portion  1203  and a lower elongate portion  1205 . A removable cartridge  1280  travels parallel with the longitudinal axis of carrier members  1202 . Cartridge  1280  is configured to slidingly receive carrier member  1202  and stylet  1230 . As such, carrier member  1202  has a lumen  1224  in intra-cochlear region  1204 . Rather, stylet  1230  extends through cartridge  1280  in extra-cochlear region  1206  (not shown) and incision region  1240 , and extends through lumen  1205  in intra-cochlear region  1204 . In incision region  1240  lower elongate portion  1205  is at least partially absent to provide a non-communicative lumen in incision region  1240 , although any of the above or other embodiments of the present invention may be implemented to provide a non-communicative lumen in incision region  1240 . Removal cartridges  1280  may be connected to stylet  1230  to enable the surgeon to guide the stylet out of lumen  1224  by removing cartridge  1280 . 
     In the above exemplary embodiments, the carrier member has been described as comprising an upper elongate portion and a lower elongate portion with the lumen extending through the lower elongate portion of one or more contiguous regions of the electrode assemblies. As one of ordinary skill in the art should find apparent, this distinction between upper elongate portion and lower elongate portion is arbitrary and presented for ease of description only. For example, the upper and lower elongate portions of the carrier member may be part of an integrated or unitary carrier member. Furthermore, there is no restriction with regard as to where in the carrier member the lumen is located. For example, the lumen may extend through the lower elongate portion, the upper elongate portion, or some combination thereof. 
     Although the present invention has been fully described in conjunction with several embodiment thereof with reference to the accompanying drawings, it is to be understood that various changes and modifications may be apparent to those skilled in the art. For example, it should be understood, that any of the above-described embodiments of the present invention may be combined in any way feasible to attain a non-communicative lumen of the present invention. As another example, the foregoing embodiments of the present invention may also have a distal opening in the intra-cochlear lumen or portion of the lumen that extends into the cochlea. This may create an open lumen at the tip. An open lumen would not increase the potential for an transport of organic material across the cochleostomy since the lumen is sealed at incision region  142 . Further, the foregoing exemplary embodiments may also be a combination of plugs at any different openings in the lumen to further convert portions of the lumen to non-communicative pathways. As another example, embodiments of the present invention utilize carrier members made of silicone, polymers, and/or other biocompatible materials suitable for implantation and which may be configured to attach to electrode assemblies. Also, further applications of stylet insertion devices and carriers are described in the U.S. Pat. No. 6,421,569 and US Patent Published Application Nos. 2004/0236390, 2004/0172118, 2004/0122501, 2004/0030376, 2003/0181967, 2003/0171758, 2003/0093139, 2003/0045921, and 2002/0029074, the entire contents and disclosures of which are hereby incorporated by reference herein. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims, unless they depart therefrom. 
     All documents, patents, journal articles and other materials cited in the present application are hereby incorporated by reference. 
     It is to be understood that the detailed description and specific examples, while indicating embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.