Endosteal electrode

Abstract

An implantable tissue-stimulating device comprising an elongate electrode carrier member ( 11 ) having a plurality of electrodes thereon. The electrodes are preferably disposed in a linear array on the carrier member ( 11 ) and are adapted to apply a preselected tissue stimulation to the cochlea. The carrier member ( 11 ) is preformed from a resiliently flexible biocompatible silicone and extends from a distal end ( 12 ) to a stop member ( 13 ). The carrier member ( 11 ) is adapted for intracochlear but extraluminar insertion within the cochlea of an implantee. In particular, the carrier member ( 11 ) is adapted to be implanted in the crevice ( 21 ) between the spiral ligament ( 22 ) and the endosteum ( 23 ) of the lateral wall of the cochlea ( 20 ). This is a quite different location to the normal placement of the cochlear implant electrode array in the scala tympani ( 24 ) of the cochlea ( 20 ). The placement of the carrier member ( 11 ) is designed to avoid any breach of the internal ducts of the cochlea ( 20 ), such as the scala tympani ( 24 ) and scala vestibuli ( 25 ) so that the normal hydrodynamic behaviour of the cochlea ( 20 ) is not affected by any intrusive device. By preservng the normal hydrodynamic behaviour of the cochlea ( 20 ), use of the carrier member ( 11 ) maximises the possibility of also preserving any hearing of the implantee that is offered by the cochlea ( 20 ). Use of the device in a system for masking or treating the symptoms of tinnitus is also described.

1 . An implantable tissue-stimulating device having a carrier member having at least one electrode thereon, the carrier member being adapted for intracochlear but extraluminar insertion within the cochlea of an implantee.  
     
     
         2 . An implantable tissue-stimulating device for use in the masking or treatment of the symptoms of tinnitus, the device having a carrier member having at least one electrode thereon, the carrier member being adapted for intracochlear but extraluminar insertion within the cochlea of an implantee.  
     
     
         3 . An implantable tissue-stimulating device when used in the masking or treatment of the symptoms of tinnitus, the device having a carrier member having at least one electrode thereon, the device being adapted for intracochlear but extraluminar insertion within the cochlea of an implantee.  
     
     
         4 . An implantable tissue-stimulating device of  claim 1  wherein the carrier member has a body having a plurality of electrodes mounted thereon.  
     
     
         5 . An implantable tissue-stimulating device of  claim 4  wherein the electrodes are disposed in an array on the carrier member and are adapted to apply a preselected tissue stimulation.  
     
     
         6 . An implantable tissue-stimulating device of  claim 1  wherein the carrier member is implantable in a crevice between the spiral ligament and the endosteum of the lateral wall of the cochlea.  
     
     
         7 . An implantable tissue-stimulating device of  claim 6  wherein the carrier member has a maximum length of about 7 mm-10 mm, a width of about 0.6 mm and a thickness no greater than about 0.2 mm and, more preferably, about 0.1 mm.  
     
     
         8 . An implantable tissue-stimulating device of  claim 6  wherein the carrier member has an inner surface and an outer surface, the inner surface being adapted on implantation to face inwardly into the cochlea.  
     
     
         9 . An implantable tissue-stimulating device of  claim 8  wherein the inner face has a concave surface and the outer face has a convex surface.  
     
     
         10 . An implantable tissue-stimulating device of  claim 1  wherein a stop member extends outwardly from the carrier member substantially at right angles to the longitudinal axis of the carrier member.  
     
     
         11 . An implantable tissue-stimulating device of  claim 10  wherein the stop member has a length of between about 1.5 and 2.0 mm.  
     
     
         12 . An implantable tissue-stimulating device of  claim 1  wherein the electrodes of the carrier member receive stimulation signals from an implantable stimulator means.  
     
     
         13 . An implantable tissue-stimulating device of  claim 12  wherein the stimulator means is housed within a housing that also houses a receiver means that is adapted to receive signals from a controller means.  
     
     
         14 . An implantable tissue-stimulating device of  claim 13  wherein the controller means comprises a processor means adapted to output one or more stimulation regimes to the stimulator.  
     
     
         15 . An implantable tissue-stimulating device of  claim 14  wherein, where the device is being used to mask or treat the symptoms of tinnitus, the stimulation regime is selected from the group comprising a random continuous sub-threshold stimulation regime, a random continuous supra-threshold stimulation regime, and a random discontinuous supra-threshold stimulation regime.  
     
     
         16 . An implantable tissue-stimulating device of  claim 14  wherein, where the device is being used to mask or treat the symptoms of tinnitus, the stimulation regime comprises a treatment-on-demand regime.  
     
     
         17 . An implantable tissue-stimulating device of  claim 16  wherein the controller means further has an activation means that allows the implantee or a third person to activate the processor means when required.  
     
     
         18 . An implantable tissue-stimulating device of  claim 14  wherein, where the device is being used to provide a hearing sensation, the controller means comprises a speech processor adapted to receive signals output by a microphone and encode the sound detected by the microphone into a sequence of electrical stimuli following given algorithms.  
     
     
         19 . An implantable tissue-stimulating device of  claim 18  wherein the speech processor is adapted to receive signals from the microphone when external sounds, such as speech, are present and to output a stimulation regime, when no external sounds are present, that is adapted to mask or treat the symptoms of tinnitus.  
     
     
         20 . An implantable tissue-stimulating device of  claim 14  wherein the controller means is implantable and contained within a hermetically sealed housing or a housing used for the stimulator means.  
     
     
         21 . An implantable tissue-stimulating device of  claim 20  wherein the controller means has an activation means that provides the implantee or a third person with a means to activate a stimulation regime when required.  
     
     
         22 . A method of inserting a tissue-stimulating device as defined in  claim 1  into a cochlea of an implantee, the method comprising the steps of: 
 performing a fenestration to access the crevice of the cochlea between the spiral ligament and the endosteum of the lateral wall of the cochlea;    placing the device in the crevice; and    sealing the fenestration.    
     
     
         23 . A method of treating the symptoms of tinnitus comprising inserting a device as defined in  claim 1  into a cochlea of an implantee, the method comprising the steps of: 
 performing a fenestration to access the crevice of the cochlea between the spiral ligament and the endosteum of the lateral wall of the cochlea;    placing the device in the crevice; and sealing the fenestration.