Electrode array for hybrid cochlear stimulator

• US 6,889,094 B1
• Filed: 05/12/2000
• Issued: 05/03/2005
• Est. Priority Date: 05/14/1999
• Status: Expired due to Fees

• Current Assignee: Advanced Bionics AG (Sonova Holding AG)
• Original Assignee: Advanced Bionics Corporation (Sonova Holding AG)
• Inventors: Harrison, William Vanbrooks, Kuzma, Janusz A., Balkany, Thomas J.
• Primary Examiner(s): Jastrzab, Jeffrey R.
• Application Number:
  US09/979,800
• Time in Patent Office: 1,817 Days
• Field of Search: 607/57, 607/137
• US Class Current: 607/137
• CPC Class Codes: A61N 1/0541 Cochlear electrodes

Abstract

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 (10) comprises a skinny, elongate carrier (12) of from 6-8 mm in length. Four to eight spaced-apart electrode contacts (14) reside along one of the flat sides of the carrier, each of which is connected to a respective wire (22) 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 (10) is inserted into the relatively straight portion of the basal end of the scala tympani duct of the cochlea through a small slit (42) 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 (32). The proximal end of the carrier may include flexible flaps (16) 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 (100) is made by forming a small (120) of about 0.4 mm diameter on the end of a very fine flexible platinum/iridium (Pt/Ir) wire (140). At a proximal end of the wire, a suitable connector (540) allows the wire to be detachably connected to a pulse generator (500).

Claims

1. A cochlear electrode array (10) comprising:

a flexible carrier (12), the flexible carrier having a proximal end, a distal end (13), a length L1 no greater than about 8 mm, and a pancake-shaped cross sectional area having opposing flat surfaces, the flat surfaces having a width W2, and the thickness of the carrier between the flat surfaces being a distance W1, wherein the distance W2 is greater than the distance W1 by at least a factor of two;

a plurality of spaced-apart electrodes (14) carried on the flexible carrier on one of the flat surfaces thereof, the flat surface carrying the electrodes comprising a medial side of the electrode array;

a plurality of wire contacts (22) embedded within the flexible carrier, at least one wire contact being connected to each electrode;

a head (18) formed at the proximal end of the flexible carrier having a cross sectional area greater than the cross-sectional area of the flexible carrier, whereby a shoulder (19) is formed at the transition from the flexible carrier to the head;

a plurality of flexible members (16) attached to the flexible carrier near its proximal end and slopping towards the head;

wherein the plurality of wire contacts pass through the head and comprise a cable (20) attached to the proximal end of the electrode array, the cable and wire contacts carried therein providing a means for making electrical contact with each of the electrodes.

2. The cochlear electrode array of claim 1 wherein the number of spaced-apart electrodes (14) carried on the medial side of the flexible carrier comprises at least four electrodes and no more than eight electrodes.

3. A method of inserting a cochlear electrode array (10) into a basal region of the scala tympani duct of a human cochlea, the cochlear electrode array having a length no greater than about 8 mm, and further having a pancake-shaped cross-sectional area, the method comprising:

forming a slit opening (42) into the basal region of the scala tympani duct,

sliding the cochlear electrode array through the slit; and

securing a proximal end of the cochlear electrode array inside of the slit, whereby the slit is plugged with the proximal end of the electrode array, thereby preventing fluids from escaping through the slit.

4. The method set forth in claim 3 wherein the step of forming the slit comprises forming a slit in the round window membrane (40) of the cochlea.

5. The method set forth in claim 4 wherein the step of forming the slit in the round window membrane further comprises orienting the slit so that its long side faces a modiolar wall (32) of the cochlea.

6. The method set forth in claim 3 wherein the step of forming the slit comprises first forming a cavity (44) in the bony structure near the basal end of the scala tympani duct, and then forming a slit in the bottom of the cavity, the slit opening into the basal region of the scala tympani duct.

7. A method of using a cochlear electrode (100) to electrically stimulate a human cochlea, the cochlear electrode comprising an insulated flexible wire (140) having a distal end and a proximal end with a ball electrode (120) attached to the distal end of the flexible wire, the method comprising the steps of:

making a small slit (190) in the round window membrane (20) of a human cochlea (30);

loading the ball electrode (120) under tension onto a distal tip (420) of a tubular insertion tool (400);

pushing the ball electrode while loaded on the distal tip of the tubular insertion tool through the slit in the round window;

removing the tubular insertion tool;

connecting a proximal end of the flexible wire to an electrical stimulator, the electrical stimulator having means for applying an electrical current to tissue near the ball electrode through the wire connected to the ball electrode and a return electrode.

8. The method of claim 7 further including controlling the stimulation pattern of electrical currents applied to the ball electrode to compensate for high frequency hearing loss.

9. The method of claim 7 further including controlling the stimulation pattern of electrical currents applied to the ball electrode to suppress tinnitus.