Implantable device migration control

Abstract

Devices and methods are disclosed for a stimulator unit in a medical device, such as an implantable component of a cochlear implant. In embodiments, the stimulator unit comprises a bottom wall configured to be substantially contacting a temporal bone of a recipient, and a top wall positioned opposite the bottom wall, wherein a cross section of the stimulator unit has an outer profile substantially parallel to the bottom wall and the top wall.

1 . A stimulator unit of an implantable device, comprising:
 a bottom wall configured to be substantially contacting a temporal bone of a recipient; and   a top wall positioned opposite to the bottom wall;   
       wherein a cross section of the stimulator unit is substantially parallel to the bottom wall and the top wall. 
     
     
         2 . The stimulator unit of  claim 1 , wherein the bottom wall has a first edge, a second edge, a third edge and a fourth edge, and
 wherein the top wall has a first edge substantially parallel to the first edge of the bottom wall and a second edge substantially parallel to the second edge of the bottom wall.   
     
     
         3 . The stimulator unit of  claim 2 , wherein the stimulator unit further comprises a first side wall, a second side wall, a third side wall and a fourth side wall,
 wherein the first side wall intersects the third side wall to form a first corner and the second side wall intersects the third side wall to form a second corner, and   wherein an angle formed by the first corner is obtuse and an angle formed by the second corner is obtuse.   
     
     
         4 . The stimulator unit of  claim 3 , wherein the second side wall intersects the fourth side wall to form a third corner and the fourth side wall intersects the first side wall to form a fourth corner, and wherein the angle formed by the third corner is acute and the angle formed by the fourth corner is acute. 
     
     
         5 . The stimulator unit of  claim 4 , wherein one or more of the first corner, the second corner, the third corner and the fourth corner are rounded. 
     
     
         6 . The stimulator unit of  claim 2 , wherein one or more of the first edges and second edges are rounded. 
     
     
         7 . The stimulator unit of  claim 2 , wherein the first edge of the bottom wall and the second edge of the bottom wall are substantially the same length, and wherein the first edge of the top wall and the second edge of the top wall are substantially the same length. 
     
     
         8 . The stimulator unit of  claim 4 , wherein the distance between the first corner and second corner is shorter than the distance between the third corner and fourth corner. 
     
     
         9 . The stimulator unit of  claim 1 , wherein the cross section of the stimulator unit has an outer profile in the shape of a trapezoid. 
     
     
         10 . The stimulator unit of  claim 1 , wherein the cross section of the stimulator unit has an outer profile in the shape of a triangle. 
     
     
         11 . The stimulator unit of  claim 1 , wherein the cross section of the stimulator unit has an outer profile in the shape of a diamond. 
     
     
         12 . The stimulator unit of  claim 2 , wherein the first parallel edges form a first side wall and the second parallel edges form a second side wall, wherein the first side wall and second side wall are on opposite sides of the stimulator unit and are non-parallel. 
     
     
         13 . The stimulator unit of  claim 3 , wherein the first side wall, second side wall and third side wall each comprise an aperture. 
     
     
         14 . The stimulator unit of  claim 13 , wherein the stimulator unit further comprises a first feedthrough wherein the first feedthrough is configured to be disposed into the aperture in the first side wall. 
     
     
         15 . The stimulator unit of  claim 14 , wherein the stimulator unit further comprises a second feedthrough, wherein the second feedthrough is configured to be disposed into the aperture in the second side wall. 
     
     
         16 . The stimulator unit of  claim 15 , wherein the stimulator unit further comprises a third feedthrough, wherein the third feedthrough is configured to be disposed into the aperture in the third side wall. 
     
     
         17 . The stimulator unit of  claim 16 , wherein the first feedthrough, second feedthrough and third feedthrough each comprise a set of electrode pins. 
     
     
         18 . The stimulator unit of  claim 16 , further comprising a first electrode lead electrically connected to the first feedthrough, a second electrode lead electrically connected to the second feedthrough and a third electrode lead electrically connected to the third feedthrough. 
     
     
         19 . The stimulator unit of  claim 18 , wherein the first electrode lead is configured to be routed along a portion of the first side wall, around the first corner and along a portion of the third side wall. 
     
     
         20 . The stimulator unit of  claim 19 , wherein the second electrode lead is configured to be routed along a portion of the second side wall, around the second corner and along a portion of the third side wall. 
     
     
         21 . The stimulator unit of  claim 20 , wherein the first, second and third electrode leads are configured to be routed away from the stimulator unit at an angle substantially normal to the third side wall. 
     
     
         22 . The stimulator unit of  claim 21 , wherein at least one of the first, second and third electrode leads electrically connect to an electrode array. 
     
     
         23 . The stimulator unit of  claim 15 , further comprising a first electrode lead electrically connected to the first feedthrough and a second electrode lead electrically connected to the second feedthrough. 
     
     
         24 . The stimulator unit of  claim 23 , wherein the first electrode lead is configured to be routed along a portion of the first wall, around the first corner and along a portion of the third side wall. 
     
     
         25 . The stimulator unit of  claim 24 , wherein the third electrode lead is configured to be routed along a portion of the second wall, around the third corner and along a portion of the third side wall. 
     
     
         26 . The stimulator unit of  claim 25 , wherein the first and second electrode leads are configured to be routed away from the stimulator unit at an angle substantially normal to the third side wall. 
     
     
         27 . The stimulator unit of  claim 26 , wherein at least one of the first and second electrode leads electrically connect to an electrode array. 
     
     
         28 . The stimulator unit of  claim 1 , wherein the bottom wall has a concave shape with respect to the top wall. 
     
     
         29 . The stimulator unit of  claim 1 , further comprising an implantable coil. 
     
     
         30 . The stimulator unit of  claim 29 , further comprising a coil lead connected to the implantable coil and connected to the stimulator unit. 
     
     
         31 . The stimulator unit of  claim 1 , further comprising an overmoulding configured to physically cover and hermetically seal the stimulator unit. 
     
     
         32 . The stimulator unit of  claim 31 , wherein the overmoulding comprises at least one aperture configured to receive an electrode lead or a coil lead. 
     
     
         33 . A cochlear implant comprising at least two stimulator units as claimed in  claim 1 . 
     
     
         34 . The stimulator unit of  claim 33 , wherein the at least two stimulator units are configured to be implanted in the temporal bone of a recipient in a fanned arrangement. 
     
     
         35 . The stimulator unit of  claim 34 , further comprising a lead connected to the at least two stimulator units. 
     
     
         36 . A method of implanting a stimulator unit of an implantable device in a recipient, comprising:
 implanting a first guide post into a temporal bone of the recipient;   implanting a second guide post into the temporal bone of the recipient;   forming a recess into the temporal bone of the recipient in between the first guide post and the second guide post; implanting a stimulator unit into the recess, wherein the stimulator unit comprises a first side wall and a second side wall, wherein the first side wall and second side wall are tapered towards one end of the stimulator unit;   wherein the first guide post contacts the first side wall, and wherein the second guide post contacts the second side wall.   
     
     
         37 . The method of  claim 36 , wherein the first side wall interacts with the first guide post and the second side wall interacts with the second guide post to secure the implantable device within the recess. 
     
     
         38 . The method of  claim 36 , wherein the recess further comprises two recess walls, wherein drilling the recess into the temporal bone further comprises drilling a ramped recess wherein the height of the recess walls increase as the recess becomes deeper. 
     
     
         39 . The method of  claim 36 , wherein the first guide post and the second guide post are screws. 
     
     
         40 . The method of  claim 36 , wherein the first guide post and the second guide post are studs. 
     
     
         41 . The method of  claim 36 , wherein the first guide post and the second guide post are fixation pins. 
     
     
         42 . The method of  claim 36 , wherein the distance between the midpoint of the first side wall and the midpoint of the second side wall is substantially the same as the distance between the first guide post and the second guide post. 
     
     
         43 . The method of  claim 38 , further comprising drilling undercuts into the recess walls, wherein the recess walls hang over the implanted implantable device. 
     
     
         44 . A method for implanting an implantable component adjacent to a skull of a recipient, wherein the implantable component may travel along a migration path subsequent to implantation, the method comprising:
 forming a recess into the temporal bone of the recipient wherein the recess includes a first guide and a second guide; and   implanting a housing, tapered in a plane parallel to a surface of the skull, into the recess;   wherein the housing contacts the first guide and the second guide, and   wherein the first guide and the second guide are configured to prevent migration of the housing.   
     
     
         45 . The method of  claim 44 , wherein the first guide and the second guide are configured to guide the housing into a recess in the skull. 
     
     
         46 . The method of  claim 45 , wherein the first guide and the second guide are opposite walls of the recess. 
     
     
         47 . The method of  claim 44 , wherein the housing further comprises top and bottom walls connected by at least two side walls. 
     
     
         48 . The method of  claim 47 , wherein a first side wall of the at least two side walls contacts the first guide and wherein a second side wall of the at least two side walls contacts the second guide.