Vestibular stimulation prosthesis

Abstract

A vestibular stimulation prosthesis can restore vestibular function in recipients having vestibular deficiency. In an example, a body is appended onto or within the recipient's ossicular chain such that the body directly interfaces with an oval window of an inner ear of the recipient. Electrical stimulation is provided using one or more electrodes of the body to stimulate the vestibular system and thereby restore vestibular functioning. In an example, a stimulator device connected to the body via a lead is also implanted. The stimulator device can have a small and convenient form factor. In some instances, the stimulator device is a stand-alone device that is configured to provide stimulation to the recipient's vestibular system without respect to signals received from devices external to the recipient. In some implementations, the stimulator device is a component of a sensory prosthesis (e.g., a cochlear implant or bionic eye) or another medical device.

What is claimed is: 
     
         1 . An apparatus comprising:
 a flexible body having one or more electrodes;   an implantable housing remote from the flexible body;   a stimulator disposed in the implantable housing and configured to deliver stimulation to vestibular tissue of a recipient through an oval window of the recipient via the one or more electrodes; and   a lead for electrically connecting the one or more electrodes to the stimulator.   
     
     
         2 . The apparatus of  claim 1 , wherein the one or more electrodes each comprise a respective tip configured to resist penetrating oval window tissue. 
     
     
         3 . The apparatus of  claim 1 , wherein the one or more electrodes are configured to penetrate the oval window tissue to a depth of 1 mm or less. 
     
     
         4 . The apparatus of  claim 1 , wherein the apparatus is configured to preserve inner ear anatomy of the recipient. 
     
     
         5 . The apparatus of  claim 1  wherein the flexible body defines:
 a first surface configured to contact oval window tissue; and 
 a second surface configured to contact a portion of an ossicular chain of the recipient. 
 
     
     
         6 . The apparatus of  claim 5 , wherein the flexible body is configured to conduct vibrations from the ossicular chain to the oval window tissue. 
     
     
         7 . The apparatus of  claim 1 , wherein the stimulator is configured to deliver stimulation to vestibular tissue of the recipient through the oval window via the one or more electrodes without respect to a communication from a source external to the recipient. 
     
     
         8 . The apparatus of  claim 1 ,
 wherein the flexible body has an elongate shape and a thickness less than a width;   wherein the flexible body comprises a shape of an n-sided polygon, where n is an integer three or greater;   wherein the flexible body comprises a shape of an n-pointed star polygon, where n is an integer three or greater;   wherein the one or more electrodes comprise a pyramidal shape having an n-sided base, where n is an integer three or greater;   wherein the one or more electrodes comprise three or more electrodes arranged linearly;   wherein the one or more electrodes have a length selected to penetrate the oval window to a depth of depth of 2.5 mm or less, 2 mm or less, 1.5 mm, or less, 0.5 mm or less;   wherein the apparatus further comprises a non-rechargeable battery disposed in the implantable housing for powering the stimulator; or   wherein each respective tip has a blunt shape, thereby being configured to resist penetrating the oval window tissue.   
     
     
         9 . A method comprising:
 surgically accessing an implantation area in a recipient;   placing one or more electrodes of a flexible body of a vestibular stimulation prosthesis proximate an oval window of the recipient;   implanting the flexible body at least partially in contact with an ossicular chain of the recipient; and   finishing implantation.   
     
     
         10 . The method of  claim 9 , wherein implanting the flexible body includes placing the flexible body between a stapes of the ossicular chain and the oval window. 
     
     
         11 . The method of  claim 9 , wherein placing the one or more electrodes of the flexible body proximate the oval window includes:
 placing the one or more electrodes in contact with the oval window without the one or more electrodes penetrating the oval window.   
     
     
         12 . The method of  claim 9 , wherein implanting the flexible body includes:
 performing a mastoidectomy;   enlarging a posterior tympanotomy; and   excavating ossicular chain tissue define a location for implanting the flexible body.   
     
     
         13 . The method of  claim 9 , further comprising:
 calibrating the vestibular stimulation prosthesis;   providing therapeutic stimulation with the vestibular stimulation prosthesis.   
     
     
         14 . The method of  claim 9 ,
 wherein the method further includes inserting electrodes of the flexible body through the oval window to a depth of 2.5 mm or less, 2 mm or less, 1.5 mm, or less, 1 mm or less, or 0.5 mm or less;   wherein the method further includes positioning a portion of the flexible body at which electrodes are disposed such that the electrodes face an area where otolith organs of the recipient are believed to be disposed;   wherein the method further includes placing a material between the flexible body and a facial nerve of the recipient;   wherein the method further includes connecting the flexible body to one or more bones of the recipient's ossicular chain;   wherein the method further includes removing an incus of the recipient's ossicular chain to make room for the flexible body;   wherein implanting the flexible body includes transtympanically implanting the flexible body;   wherein the method further calibrating the vestibular stimulation prosthesis by performing vestibular response telemetry;   wherein the method further calibrating the vestibular stimulation prosthesis by determining which the one or more electrodes of the flexible body are best able to stimulate target anatomy; or   wherein the method further comprises calibrating the vestibular stimulation prosthesis at least one month after implantation.   
     
     
         15 . A method comprising:
 via a flexible body disposed in a recipient:
 conducting vibrations from an ossicular chain to an inner ear of the recipient; and 
 electrically stimulating vestibular tissue of the recipient. 
   
     
     
         16 . The method of  claim 15 , wherein electrically stimulating the vestibular tissue of the recipient includes:
 electrically stimulating the vestibular tissue using one or more electrodes of the flexible body.   
     
     
         17 . The method of  claim 15 , further comprising:
 generating a stimulation signal at a stimulator device remote from the flexible body; and   transmitting the stimulation signal to one or more electrodes of the flexible body via a lead electrically connecting the stimulator device with the one or more electrodes.   
     
     
         18 . The method of  claim 15 ,
 wherein electrically stimulating the vestibular tissue of the recipient includes providing electrical stimulation through an oval window of the recipient;   wherein electrically stimulating the vestibular tissue of the recipient includes repeating the stimulating every forty minutes to one hour for an amount of time;   wherein electrically stimulating the vestibular tissue of the recipient includes providing stimulation at a rate within the range of 200 Hz to 1000 Hz, inclusive;   wherein electrically stimulating the vestibular tissue of the recipient includes providing stimulation at a different rate at different electrodes;   wherein electrically stimulating the vestibular tissue of the recipient includes providing stimulation via a first electrode at a rate of 900 Hz and at via a second electrode at a rate of 500 Hz; or   wherein conducting vibrations from a vestibular chain to the inner ear of the recipient includes attenuating the vibrations, thereby resulting in hearing loss for the recipient of at least 5 decibels.   
     
     
         19 - 25 . (canceled) 
     
     
         26 . The apparatus of  claim 1 , further comprising:
 a reference electrode;   a reference electrode lead coupled to the reference electrode for electrically coupling the reference electrode to the implantable housing; and   a reference electrode fastener configured to fasten the reference electrode to middle ear anatomy.   
     
     
         27 - 29 . (canceled) 
     
     
         30 . The apparatus of  claim 26 ,
 wherein the reference electrode defines an opening through which the reference electrode fastener can extend;   wherein the reference electrode fastener comprises a spring that forces together a distal portion of the reference electrode fastener;   wherein the reference electrode fastener comprises a spring that forces apart a proximal portion of the reference electrode fastener;   wherein the reference electrode fastener comprises one or more of the following fasteners: clips, screws, hooks, clamps, fasteners, adhesives, or cements;   wherein the reference electrode comprises a triangular shape with a point configured to pierce tissue;   wherein the reference electrode comprises a barb configured to resist removal of the reference electrode and thereby facilitate affixing the reference electrode in tissue;   wherein the reference electrode comprises a plurality of rows of barbs; or   wherein the reference electrode comprises one or more fins configured to pierce or slice tissue during implantation of the reference electrode to facilitate affixing the reference electrode in tissue.