Advanced Bionics Corporation

Thomas J Balkany

Janusz A Kuzma

William Vanbrooks Harrison

Thomas H R Lenarz

Alfred E Mann

Michael Steven Colvin

Chuladatta Thenawara

Implantable electrode leads, e.g. cochlear, spinal cord stimulation, or any type of neurostimulation leads, used in a patient's body to stimulate muscle or nerve tissue, provide enhanced stimulation for treating, e.g., hearing loss or chronic pain. One such lead includes, an implantable electrode array, adapted for insertion into a cochlea, which lead provides improved stability of electrode contact direction. In-line electrodes are spaced-apart along one side of a flexible carrier having non-conductive bumps coated with a bioresorbable material spaced apart between each electrode contact. Over time the bioresorbable material is absorbed thereby reducing chronic placement pressure caused during the insertion of the electrode array into the cochlea. The bioresorbable material may also serve as a carrier for drugs or other materials that would improve performance of the electrode for any type of lead.

Coated electrode array having uncoated electrode contacts

An insertion tool uses a stylet wire to help guide an electrode system into a cochlea. The insertion tool includes three main elements or parts: a handle, a guide and a slider. The handle is made from light stainless steel tube flattened in front with a machined slot. The guide consists of a plurality of metal tubes, fixed to each other within a holding bracket. In one embodiment, the slider includes a stabilizer wire, a long stylet wire, and a short stylet wire. During the assembly process, the stabilizer and stylet wires are inserted into respective tubes of the guide and the end of the stabilizer wire is bent to form an offset. The electrode system is loaded onto the tool by inserting the short stylet wire into a holder that supports the electrode lead.

Insertion tool for placement of electrode system inside the cochlear lumen

A cochlear electrode array is adapted for implantation within the basal end of the scala tympani duct of a human cochlea. A first embodiment of the cochlear electrode array () comprises a skinny, elongate carrier () of from 6-8 mm in length. Four to eight spaced-apart electrode contacts () reside along one of the flat sides of the carrier, each of which is connected to a respective wire () embedded within the carrier. The wires exit a proximal end of the carrier via a wire bundle. The wire bundle, in turn, is connectable to an implantable cochlear stimulator (ICS) or equivalent pulse generator. The electrode array () is inserted into the relatively straight portion of the basal end of the scala tympani duct of the cochlea through a small slit () made in the round window membrane that separates the cochlea from the middle ear. The slit is oriented so as to place the electrode contacts facing the modiolar wall (). The proximal end of the carrier may include flexible flaps () or tines that maintain the electrode array in its desired position within the basal end of the cochlea. Such tines or flaps further help seal the carrier against the slit opening to present fluids from escaping the cochlea. The cochlea thus remains filled with fluid which can activate hair cells as fluid waves are established through motion of the round window membrane. In use, electrical stimulation is provided only to the basal end of the cochlea through the electrode array to supplement hearing of high frequency sounds. Normal hearing (activation of hair cells through fluid motion) occurs at the apex and middle regions of the cochlea for sensing lower frequency sounds. A second embodiment of the cochlear electrode () is made by forming a small () of about 0.4 mm diameter on the end of a very fine flexible platinum/iridium (Pt/Ir) wire (). At a proximal end of the wire, a suitable connector () allows the wire to be detachably connected to a pulse generator ().

Electrode array for hybrid cochlear stimulator

A hybrid cochlear implant hearing aid sytem ( ) provides low frequency acoustic energy boost, if needed, and high frequency direct neural stimulation. Tinnitus suppression may also be provided. The neurons responsible for sensing high frequency sounds are located at the basal end of the cochlea. A short basal electrode ( ) that extends into the cochlea only at the basal region allows direct stimulation of these neurons by an appropriately-controlled cochlear stimulator ( ). The basal electrode array typically has from four to eight electrode contacts ( ). The design of the electrode array allows the surgeon to place the array using minimally invasive surgical techniques and requires no cochleostomy. The electrode array is thin, and can typically be inserted directly through the round window membrane to make contact with, or to be positioned in close proximity to, the modiolus wall in the basal region of the cochlea. The hybrid implantable cochlear stimulator and hearing aid system relies primarily on the cochlear stimulator portion of the system for being able to sense high frequency sounds, and relies primarily on normal hearing processes, or other acoustic boosting devices and systems, for being able to sense lower frequency sounds.

Hybrid implantable cochlear stimulator hearing aid system

A threaded grommet, having an axial passageway therethrough, and made from a biocompatible material, such as titanium, is screwed into a cochleostomy made in the bony tissue adjacent the round window in order to provide a minimally-invasive access port into the cochlea. The threads included on the outside of the grommet engage the bony tissue and form a tight seal that holds the grommet securely in position. Such tight seal prevents cochlear fluids from escaping from inside of the cochlea. The axial passageway through the center of the grommet provides an opening, i.e., mechanical access, into the base end (the end of the cochlea nearest the round window) of the cochlea. Drugs, steroids, tissue-growth-inhibiting fluids, and the like, may be controllably delivered through the access hole into the cochlea, which access hole may be plugged when not needed. Additionally, an electrode array, e.g., a relatively short electrode array may, be inserted into the cochlea through the access hole. A preferred electrode array has from four to eight electrode contacts spaced apart along a flexible carrier. The flexible carrier is about 6-8 mm in length. The electrode contacts may be connected, in conventional manner, to suitable implantable cochlear stimulator (ICS), or equivalent pulse generator. Neither the grommet nor the short electrode array interfere with the normal hearing processes within the cochlea. Hence, both electrical stimulation and normal hearing processes may occur simultaneously within the cochlea.

Minimally-invasive access into the cochlea for electrode insertion and fluid delivery

An implantable microphone system, usable with a cochlear implant system or other hearing aid prosthesis, detects sound pressure waves (acoustic waves) at a movable member within the middle ear, e.g., the tympanic membrane or the stapes, through a fluid communication channel ( ) established between the middle ear movable member and a microphone capsule ( ). The microphone capsule ( ) includes two compartments ( ) separated by a flexible diaphragm ( ). One compartment ( ) is in fluid communication with a thin-walled balloon, filled with a suitable fluid ( ), positioned in contact with the movable member within the middle ear. The other compartment ( ) is mechanically coupled through a suitable mechanical linkage ( ) to a microphone sensor ( ). The microphone sensor, in turn, is electrically connected to the cochlear implant system or other hearing aid prosthesis.

Fluid filled microphone balloon to be implanted in the middle ear

A stapedius electrode attaches to or is embedded within the stapedius muscle (,) at a point near where the stapedius muscle is visible as it exits a bony channel (,) within the middle ear. In one embodiment, the electrode is made from a biocompatible metal wire formed into a flat blade (,) having a sharp tip (,) and serrations (,) along one edge. An insulated lead attaches electrically and mechanically to the blade. Such attachment may be made by welding and wrapping the insulated lead at one end of the wire around the body of the electrode and protecting such weld and securing such wrappings with a coating or blob of epoxy. During implantation of the electrode, the electrode blade is inserted through a small slot made in the muscle tissue. Alternatively, the electrode may be inserted alongside the muscle tissue through an opening in the bony wall as it passes through the bony channel, with a tip of the electrode protruding from the bony channel. The protruding tip is then bent over to lie against the bony wall, and hold the electrode in place. Other embodiments of a stapedius electrode are also presented. such as the distal end (,) of a multistrand insulated wire (,) that is embedded in the stapedius muscle tissue (,) using a delivery needle (,). A tube connector (,) may be used to electrically connect a lead coming form the implanted stapedius electrode to an implant device. The tube connector (,) includes a platinum tube (,) welded at one end to a lead (,) coming from the implant device. A proximal end (,) of the lead from the electrode is crimped to the other end of the tube (,). A silicone tube or sleeve (,) is then placed over the tube and sealed at both ends.

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Coral Gables, FL, United States of America

Thomas J Balkany