Securing an implanted medical device in a patient

Abstract

An apparatus and method for implanting and securing an implanted medical device in a recipient. The implantable medical device of the generally includes an electrode assembly that comprises an elongate carrier member having at least one stimulating electrode positioned thereon. The carrier member further has a fixation structure positioned thereon configured to interact with a portion of the rigid structure to longitudinally secure the carrier member in the recipient.

What is claimed is: 
     
         1 . An electrode assembly for implantation into a cochlea of a recipient, the electrode assembly comprising:
 an elongate electrode array including an intra-cochlear portion including at least one electrode and an extra-cochlear portion; and   a plurality of circumferentially extending projections, wherein   the electrode array includes at least one of silicone, polyurethane or PTFE, and respective circumferentially extending projections of the plurality of circumferentially extending projections have an outer profile that includes a section that increasingly extends away from a longitudinal axis of the electrode array with location along the electrode array in a direction moving away from a distal end of the electrode assembly.   
     
     
         2 . The electrode assembly of  claim 1 , wherein:
 the respective sections of the outer profile of the respective circumferentially extending projections of the plurality of circumferentially extending projections includes a maximum distance from the longitudinal axis, wherein when viewed from a side, the outer profile extends towards the longitudinal axis in a direction normal to the longitudinal axis from that maximum distance.   
     
     
         3 . The electrode assembly of  claim 1 , wherein:
 the respective sections of the outer profile of the respective circumferentially extending projections of the plurality of circumferentially extending projections form truncated cones.   
     
     
         4 . The electrode assembly of  claim 1 , wherein:
 the respective sections of the outer profile of the respective circumferentially extending projections of the plurality of circumferentially extending projections have a saw tooth configuration with a zero degree hook angle.   
     
     
         5 . The electrode assembly of  claim 1 , wherein:
 an outermost profile of a cross-section of the plurality of circumferentially extending projections is structure is symmetric about the longitudinal axis of the electrode array, the cross-section lying on a plane parallel to and on the longitudinal axis.   
     
     
         6 . The electrode assembly of  claim 1 , wherein:
 the plurality of circumferentially extending projections are all located proximally of all electrodes of the electrode array.   
     
     
         7 . The electrode assembly of  claim 1 , wherein:
 at least one of the plurality of circumferentially extending projections establish the widest part of the electrode assembly between a distal end of the electrode assembly and a beginning of a lead of the electrode assembly.   
     
     
         8 . The electrode assembly of  claim 1 , wherein:
 the respective circumferentially extending projections of the plurality of circumferentially extending projections are configured to secure the electrode assembly relative to the cochlea against movement out of the cochlea due to interaction of at least one of the respective circumferentially extending projections with bone in a head of the recipient.   
     
     
         9 . The electrode assembly of  claim 1 , wherein:
 the projections are configured to establishes a fixation structure that prevents movement of the fixation structure out of the cochlea when the electrode assembly is implanted in the cochlea.   
     
     
         10 . The electrode assembly of  claim 1 , wherein:
 the projections comprise a flexible material, and the projections are configured to establishes a flexible fixation structure that prevents movement of the flexible fixation structure out of the cochlea when the electrode assembly is implanted in the cochlea.   
     
     
         11 . An electrode assembly for implantation into a cochlea of a recipient, the electrode assembly comprising:
 an electrode array including a plurality of electrodes, wherein the electrode assembly includes at least one of silicone, polyurethane or PTFE, and wherein the electrode assembly includes a plurality of portions that, when viewed along a plane that extends longitudinally through the plurality of portions, respectively have truncated substantially triangular cross-sectional shapes.   
     
     
         12 . The assembly of  claim 11 , wherein:
 electrode assembly is configured to at least partially prevent perilymphatic fluid from escaping from the cochlea when the electrode assembly is in direct contact with the perilymphatic fluid.   
     
     
         13 . The assembly of  claim 11 , wherein:
 the portions are circumferentially-extending projections, and the plurality of electrodes are located distally of the portions.   
     
     
         14 . The assembly of  claim 11 , wherein:
 the electrode array includes a carrier member that carries the plurality of electrodes; and   the portions are configured to interact with bone in a head of a recipient to produce a longitudinal anchor force that maintains the portions in the bone, thereby retaining carrier member in a desired position in the cochlea.   
     
     
         15 . The assembly of  claim 11 , wherein:
 the electrode array includes a carrier member that carries the plurality of electrodes; and   the portions are configured to interact with bone in a head of a recipient to produce a longitudinal anchor force that prevents substantial longitudinal movement of the carrier member out of the cochlea.   
     
     
         16 . The assembly of  claim 11 , wherein:
 the electrode array includes a carrier member that carries the plurality of electrodes; and   the portions are configured to interact with bone in a head of a recipient to produce a rotational anchor force that substantially prevents rotational movement of the portions, and, as a result, rotational movement of the carrier member is also substantially prevented.   
     
     
         17 . The assembly of  claim 11 , wherein:
 the assembly is implanted in a head of a recipient; and   the portions comprise a flexible material having a diameter that is larger than a recess in bone in the head of the recipient, at least one of the portions of the plurality of portions being in the recess.   
     
     
         18 . The assembly of  claim 11 , wherein:
 the assembly is implanted in a head of a recipient; and   the portions comprise a flexible material that establishes a flexible fixation structure, at least one of the portions of the plurality of portions being compressed in a recess in bone in the head of the recipient, thus creating a longitudinal anchor force that prevents movement of the fixation structure out of the cochlea.   
     
     
         19 . The assembly of  claim 11 , wherein:
 the electrodes are half band electrodes.   
     
     
         20 . The assembly of  claim 11 , wherein:
 the electrodes are banded electrodes.   
     
     
         21 . A method of implanting a cochlear implant electrode array assembly, comprising:
 obtaining the cochlear implant electrode array assembly, the electrode array assembly including an electrode array and a lead assembly extending from the electrode array, the electrode array assembly including fixation structure;   opening an incision in a head of a person;   obtaining access to a cochlea in the head of the person;   inserting the electrode array into the cochlea; and   closing the incision, wherein   the method of implanting the electrode array assembly results in the electrode array resisting longitudinal movement of the electrode array out of the cochlea owing to interaction of the fixation structure with structure of the head, and   the fixation device includes circumferentially-extending projections that interact with the structure of the head, wherein the structure of the head is bone.   
     
     
         22 . The method of  claim 21 , wherein:
 the fixation device includes circumferentially-extending projections that interact with the structure of the head, wherein the structure of the head is bone.   
     
     
         23 . The method of  claim 21 , wherein:
 the fixation structure comprises a flexible material having a diameter that is larger than a passage through the structure of the head, and is compressed therein, thus resisting the longitudinal movement of the electrode array out of the cochlea.   
     
     
         24 . The method of  claim 21 , wherein:
 the fixation structure comprises flexible silicone having a diameter that is larger than a passage through the structure of the head, and is compressed therein, thus resisting the longitudinal movement of the electrode array out of the cochlea.   
     
     
         25 . The method of  claim 21 , wherein:
 compression of fixation structure by structure of the head creates a longitudinal anchor force that prevents movement of fixation structure out of cochlea.   
     
     
         26 . The method of  claim 21 , wherein:
 the electrode array has a tendency to exit the cochlea; and   the tendency to exit the cochlea places pressure on the fixation structure to exit the recipient, which causes circumferentially-extending projections of the fixation structure to further interact with bone, wherein this interaction produces a longitudinal anchor force that substantially prevents longitudinal movement of the fixation structure out of the recipient.   
     
     
         27 . The method of  claim 21 , wherein:
 the electrode array has a tendency to exit the cochlea; and   the tendency to exit the cochlea places pressure on the fixation structure to exit the recipient, which causes circumferentially-extending projections of the fixation structure to further interact with bone, wherein this interaction produces a longitudinal anchor force that prevents substantial longitudinal movement of carrier member out of cochlea.   
     
     
         28 . The method of  claim 21 , wherein:
 the method of implanting the electrode array assembly results in the prevention of rotational movement of the fixation structure, and thus rotational movement of the electrode array is prevented.   
     
     
         29 . The method of  claim 21 , at least one of:
 the electrode array is a straight electrode array that is forced into a spiraled configuration as a result of insertion into the cochlea, wherein the electrode assembly attempts to return to a straight configuration, and thus produces a longitudinal force that would be longitudinal movement but for the resistance; or   the electrode array assembly has a spring force which is not stabilized which thus would result in longitudinal movement but for the resistance.   
     
     
         30 . The method of  claim 21 , wherein:
 after inserting the electrode array into the cochlea, there is inadvertent pulling of the electrode array assembly, which would result in longitudinal movement but for the resistance.