Implantable expandable multicontact electrodes

• US 6,205,361 B1
• Filed: 01/28/1999
• Issued: 03/20/2001
• Est. Priority Date: 02/10/1998
• Status: Expired due to Term

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Advanced Bionics Corporation (Sonova Holding AG)
• Inventors: Mann, Carla M., Kuzma, Janusz A.
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/239,927
• Time in Patent Office: 782 Days
• Field of Search: 607/116, 607/117, 607/119, 607/129, 607/152
• US Class Current: 607/116
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/0553 Paddle shaped electrodes, e.g. for laminotomy

Abstract

A paddle-type electrode or electrode array is implantable like a percutaneously inserted lead, i.e., without requiring major surgery, but once inserted, expands to provide a platform for many electrode configurations. The electrode array is provided on a flexible, foldable, subcarrier or substrate. Such subcarrier or substrate is folded, or compressed. during implantation, thereby facilitating its insertion using simple, well-known percutaneous implantation techniques. Once implanted, such subcarrier or substrate expands, thereby placing the electrodes in a desired spaced-apart positional relationship, and thus achieving a desired electrode array configuration. A memory element is used within the subcarrier or substrate which causes the electrode array to expand or unfold to a desired unfolded or expanded state after it has been implanted while in a folded up or compressed state. Further, the electrode array includes a membrane as an integral part thereof that prevents ingrowth of tissue inside the electrode array, thereby facilitating repositioning, removal, and/or reinsertion of the electrode array, as required.

Claims

1. An implantable electrode array (10) comprising:

a silicone paddle having a perimeter edge and including a plurality of electrode contacts (11) arranged in a spaced-apart relationship along the perimeter edge;

a flexible membrane (14) formed within the area inbetween the perimeter edge;

a memory element (12) affixed to the perimeter edge, the memory element having flexible properties that allow it to bend and fold, but also having memory properties that cause it to assume a desired shape in the absence of external folding or bending forces, said memory element comprising a wire formed in the perimeter edge of the flexible membrane, said wire comprising a shape-memory element that assumes a desired shape in the absence of external forces; and

means for making electrical contact with each of the plurality of electrode contacts;

whereby the electrode array may be folded to assume a small cross-sectional area during implantation, but whereby the electrode array unfolds to assume an expanded configuration as controlled by the desired shape of the memory element after implantation.

2. The implantable electrode array of claim 1 wherein the shape-memory element comprises a wire made from a metal or a polymer.

3. The implantable electrode array of claim 2 further including an opening in the flexible membrane at a distal tip of the array, thereby exposing the wire at the distal tip, the exposed wire at the distal tip thus forming an attachment loop (13), which attachment loop may be used with an insertion stylet to help position the electrode array, once implanted.

4. An implantable electrode array comprising:

a flexible substrate;

three parallel columns of spaced-apart electrodes integrally formed on a surface of the flexible substrate; and

means for making electrical contact with each electrode in each of the plurality of parallel columns of electrodes;

the flexible substrate being foldable along an axis parallel to the parallel columns, said axis lying in the region of the flexible substrate inbetween the parallel columns of electrodes;

wherein the flexible substrate has a width of between about 6.5 and 7.0 mm and a length of about 8-12 mm, and wherein each column of spaced-apart electrodes has a thickness of between about 0.6 and 1.0 mm, and wherein the flexible substrate has a thickness in the region inbetween the parallel columns of electrodes of approximately 0.10 to 0.30 mm.

5. A system for implanting an expandable electrode array comprising:

an electrode array, the electrode array comprising;

a flexible substrate,

a plurality of parallel columns of spaced-apart electrodes integrally formed on a surface of the flexible substrate, and

means for making electrical contact with each electrode in each of the plurality of parallel columns of electrodes,

the flexible substrate normally assuming a planar flat shape, but being collapsible so as to configure the electrode array in a folded or compressed state; and

an insertion tool adapted to facilitate implantation of the electrode array into living tissue while still within its folded or compressed state, wherein the insertion tool comprises a hollow tube in which the folded or compressed electrode array may be inserted, and a loading element detachably connected to a proximal end of the hollow tube, the loading element having a funnel-shape that facilitates configuring the electrode array in its folded or compressed state from its planar flat state as said electrode array is longitudinally inserted into the hollow tube.

6. A method of implanting an expandable electrode array through the lumen of a needle, comprising:

forming an electrode array having a plurality of parallel columns of spaced apart electrodes on a flexible membrane;

folding the parallel columns of electrodes against each other;

inserting the folded parallel columns in the lumen of a needle;

injecting the needle in living tissue;

expelling the folded parallel columns of electrodes from the lumen of the needle into the living tissue by detachably connecting an insertion stylet to a distal tip of the folded electrode array, and pushing the folded electrode array out the lumen of the needle into the living tissue wherein the needle has been injected by pushing on a proximal end of the insertion stylet; and

unfolding the parallel columns of electrodes to form a paddle-type array of parallel columns of electrodes by affixing a flexible memory element to the flexible membrane, said memory element causing said flexible membrane to assume a flat planar shape in the absence of external forces, and removing external forces from the folded parallel columns of electrodes, whereby the memory element automatically forces the electrode array to unfold.

7. A system for implanting an expandable electrode array comprising:

an electrode array, the electrode array comprising;

a flexible substrate,

a plurality of parallel columns of spaced-apart electrodes integrally formed on a surface of the flexible substrate, and

means for making electrical contact with each electrode in each of the plurality of parallel columns of electrodes,

the flexible substrate normally assuming a planar flat shape, but being collapsible so as to configure the electrode array in a folded or compressed state; and

an insertion tool adapted to facilitate implantation of the electrode array into living tissue while still within its folded or compressed state, wherein the insertion tool comprises a hollow needle having a sharp distal tip, in which the folded or compressed electrode array may be inserted, and wherein the insertion tool further includes an insertion stylet adapted to engage a distal tip of the electrode array, which insertion stylet facilitates pushing the folded electrode array out of the hollow needle so that it can assume its planar flat shape.

8. The system of claim 7 wherein the hollow needle includes a longitudinal slot of sufficient width to allow the insertion stylet to pass therethrough.