WO2013166293A1

WO2013166293A1 - Rapidly deployable instrument for robotic insertion of electrode arrays

Info

Publication number: WO2013166293A1
Application number: PCT/US2013/039280
Authority: WO
Inventors: Nabil Simaan; Jason PILE
Original assignee: Vanderbilt University
Priority date: 2012-05-02
Filing date: 2013-05-02
Publication date: 2013-11-07

Abstract

An electrode array insertion device including a control lever, an electrode insertion stage, a stylet puller stage, a load sensor, and a controller. The electrode insertion stage advances an electrode array into a cochlea in response to a mechanical manipulation applied to the control lever by a user. The stylet puller stage retracts a stylet from the electrode array as the electrode array is advanced into the cochlea in response to the mechanical manipulation of the control lever. The load sensor detects a load applied to the electrode array as the electrode is advanced into the cochlea. The controller applies mechanical feedback to the control lever based on the detected load. The mechanical feedback affects the mechanical manipulation of the control lever such that it requires more force from the user to move the control lever when a load is detected on the electrode array.

Description

RAPIDLY DEPLOYABLE INSTRUMENT FOR ROBOTIC INSERTION OF

ELECTRODE ARRAYS

RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 61/641,667, filed on May 2, 2012 and titled "RAPIDLY DEPLOYABLE INSTRUMENT FOR ROBOTIC INSERTION OF ELECTRODE ARRAYS," the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to devices for positioning an electrode array. In particular, the invention relates to systems for inserting an electrode array into a cochlea for medical procedures or implantation of medical devices.

BACKGROUND OF THE INVENTION

[0003] Electrode arrays are inserted into the cochlea of a patient during cochlear implant surgery. The cochlea is a spiral-shaped structure of the inner ear. Professionals currently insert a flexible electrode array into the inner ear using tools such as tweezers or claws. However, insertion of the electrode array can be difficult due to the spiral shape of the cochlea. As such, the inner ear can be damaged as the electrode array is inserted causing permanent hearing damage.

[0004] Other systems have been proposed that utilize fully active devices such as continuum robots. The shape and position of such continuum robots are adjusted as the device is inserted into the ear to conform to the spiral shape of the cochlea. However, fully active electrode insertion systems are complex and expensive, and also require longer setup time. The device must be locked to the patient's head or a bed frame to provide a stationary reference point and the device must be registered to the anatomy of the patient.

SUMMARY

[0005] Embodiments of this invention provide semi-active robotic tools for inserting an electrode array into a cochlea. The semi-active tool provides feedback and other support for a user, but does not automate the electrode insertion process. In some embodiments, the device is hand-held and operated by a professional, such as a surgeon. The surgeon controls the insertion of the flexible array using a lever or button. A controller is integrated into the system and controls the impedance of the insertion lever and coordinates the movement of a stylet with the insertion of the electrode array.

[0006] In one embodiment, the invention provides an electrode array insertion device. The device includes a control lever, an electrode insertion stage, a stylet puller stage, a load sensor, and a controller. The electrode insertion stage advances an electrode array into a cochlea in response to a mechanical manipulation applied to the control lever by a user. The stylet puller stage retracts a stylet from the electrode array as the electrode array is advanced into the cochlea. The retraction of the stylet is coordinated with the advancement of the electrode in response to the mechanical manipulation of the control lever. The load sensor detects a load applied to the electrode array as the electrode is advanced into the cochlea. The controller applies mechanical feedback to the control lever based on the detected load. The mechanical feedback affects the mechanical manipulation of the control lever such that it requires more force from the user to move the control lever when a load is detected on the electrode array.

[0007] In another embodiment the invention provides a method of inserting an electrode array into a cochlea using an electrode array insertion device. The device includes a control lever, an electrode insertion stage, and a stylet puller stage. The method includes attaching the electrode array to the electrode array insertion stage and attaching a stylet associated with the electrode array to the stylet puller stage. The controller detects movement of the controller lever applied by a user and advances the electrode insertion stage based on the movement of the control lever. Advancing the electrode insertion stage advances the electrode array into the cochlea. The stylet puller stage is retracted based on the movement of the control lever.

Retracting the stylet puller stage retracts the stylet from the electrode array. The movement of the stylet puller stage is coordinated with the movement of the electrode insertion stage. The controller detects a load applied to the electrode array as the electrode array is advanced into the cochlea and applies a feedback signal to the control lever based on the detected load. The feedback signal mechanically affects the operation of the control lever. [0008] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Fig. 1 is a cross-sectional view of a human ear fitted with a cochlear implant.

[0010] Fig. 2 is a flow-chart illustrating a procedure for inserting an electrode into a cochlea using a semi-active insertion device.

[0011] Fig. 3 is a cross-sectional view of an electrode insertion device including a scissor grip mechanical control.

[0012] Fig. 4 is a cross-sectional view of an electrode insertion device including a slide button electronic control.

[0013] Fig. 5 is a cross-sectional view of an electrode insertion device including a tilt control mechanism.

[0014] Fig. 6 is an exploded view of the electrode insertion device of Fig. 4.

[0015] Fig. 7 is a cross-sectional and exploded view of an electrode insertion device including a tilt control mechanism in the same housing as a scissor grip control.

[0016] Fig. 8 is a detailed cross-sectional view of the insertion module of the electrode insertion device of Fig. 7.

[0017] Fig. 9 is a cross-sectional and perspective view of an electrode insertion device with parallel linkages to control the tilt angle of the insertion mechanism.

[0018] Fig. 10 is an exploded view of the electrode insertion device of Fig. 9.

[0019] Fig. 11 is a cross-sectional view of an electrode insertion device with a wire-actuation mechanism.

[0020] Fig. 12 is an exploded view of the electrode insertion device of Fig. 11. [0021] Fig. 13 is a cross-sectional view of a wire-actuated electrode insertion device according to another embodiment.

[0022] Fig. 14 is a perspective view of the electrode insertion device of Fig. 14.

[0023] Fig. 15 is a schematic illustration of a wire-actuated electrode insertion device according to a third embodiment.

[0024] Fig. 16 is a side and top view of the electrode insertion device of Fig. 14.

[0025] Fig. 17 is a cross-section view of a positioning leg of the electrode insertion device of Fig. 14.

[0026] Fig. 18 is an exploded view of a motor assembly of the electrode insertion device of Fig. 14.

[0027] Fig. 19 is a perspective view of a control unit for an electrode insertion device. DETAILED DESCRIPTION

[0028] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

[0029] A cochlear implant is a surgically implanted device that provides a sense of sound to a person who is deaf or severely hearing impaired. In some cochlear implants, such as illustrated in Fig. 1, a receiver/transmitter pairing 101 are installed near the surface of the patient's head. An electrode array 103 is communicatively connected to the receiver/transmitter unit 101 and is positioned inside the spiral-shaped cochlea 105 of the patient. The electrode array 103 stimulates the cochlea 105 to provide a sense of sound.

[0030] The devices and systems described below assist a surgeon in inserting the electrode array into the cochlea 105. The system inserts the electrode array 103 further into the cochlea 105 while retracting a stylet that helps guide the electrode array 103 through the cochlea 105. The system detects forces on the electrode array as it is inserted and provides feedback to the surgeon through the control mechanism (e.g., a control lever or slider switch).

[0031] Fig. 2 describes a method for installing a cochlear implant using the electrode array insertion devices described below. First, a new electrode array is loaded into the electrode insertion tool (step 201). The patient is prepared and a "round window" incision or

cochleostomy is performed to expose the insertion site for the electrode array (step 203). A calibrated imaging system is used to digitize the insertion site (step 205) to assist in determining the proper orientation and position for the tool. If lubricant is necessary, it is added at this point (step 207). The hand-held device is then positioned at a anatomically correct orientation for electrode insertion (step 209). The surgeon then operates the insertion lever or control slide (step 211) to control the insertion of the electrode array. The device continuously monitors hand motions and forces detected on the electrode array as it is inserted into the cochlea (step 213). The device provides feedback to the user (step 215) through impedance applied to the control lever or slide switch. In other words, as the electrode array encounters resistance as it is inserted into the cochlea, the insertion lever becomes more difficult to move. When the electrode array is inserted to the proper depth, the device releases the electrode array and the insertion process is complete (step 217).

[0032] Fig. 3 illustrates a first example of an electrode array insertion device. In this device, the control lever 311 is mechanically coupled to both the electrode push rod 305 and the stylet push rod 304. The electrode array 301 is placed with its stylet 303 held in the holder of the stylet push rod 304 and the electrode held in a grip of the electrode push rod 305. The electrode array receiver 302 is clipped to the exterior of the tool. The system mechanically coordinates the movement of the stylet push rod 304 with the electrode push rod 305 such that the retraction of the stylet is mechanically coupled to the insertion of the electrode array 301. When the user moves the control lever 311, a gear 309 rotates causing the rotation of a mechanical linkage 308 rotates and simultaneously pushes the electrode 301 and pulls the stylet 303. One end of the mechanical linkage 308 is connected to the electrode push rod 305 by link 307. The opposite end is connected to the stylet push rod 304 by link 310. Load cell 306 monitors resistance to the insertion of the electrode array 301 by monitoring the load on the electrode array push rod 305. A braking motor 313 applies an amplified resistance to the control level 311 through rack 312. The mechanical impedance/resistance applied to the control lever 311 is based on the force sensed by the load cell 306.

[0033] Fig. 4 illustrates another example of an electrode insertion device. Again, the electrode 401 is placed in a gripper at the distal end of an electrode push rod 405 while the stylet 403 is held by the distal end of a stylet push rod 404. The receiver 402 is again clipped to the side of the device as the electrode array 401 is inserted. However, instead of a mechanical linkages between the electrode push rod 405 and the stylet push rod 404, two separate motors 407 and 408 are used to independently control push or pull at the electrode push rod 305 and the stylet push rod 404, respectively. A load cell 406 again monitors the mechanical resistance on the electrode push rod 405 and provides impedance feedback to the insertion control 409. In the example of Fig. 4, the insertion control 409 is in the form of a slide lever.

[0034] To provide an additional degree of freedom and increased control during the insertion process, a tilting mechanism can be added to assist in adjusting the insertion angle of the electrode array. The insertion point of the cochlea is referred to here as the remote center of motion (RCM). Fig. 5 illustrates an example of an electrode array insertion device with a tilting mechanism. The electrode array 501 is positioned in a gripper at the distal end of the electrode push rod 505. The stylet 503 is held by the distal end of the stylet push rod 504. The receiver of the implant device 502 is again clipped to the side of the device. The electrode push rod 505 is pushed by motor 508 as the stylet push rod 504 is retracted by motor 509. The insertion of the electrode array 501 and retraction of the stylet 503 are controlled by the insertion lever 512. The insertion lever is coupled to an impedance motor 510 through a mechanical linkage 511. The impedance motor monitors movement of the control lever 512 while also applying feedback to the control lever 512 based on mechanical resistance detected by the load cell 506. Unlike the examples described above, the electrode array insertion device also includes a rotation motor 513 that causes the front portion of the insertion device to rotate about the remote center of motion 514.

[0035] Fig. 6 is an exploded view of the device of Fig. 5. Components that are also illustrated in Fig. 5 include the same numbering as above. The controller lever 512 and the second grip portion 521 of the scissor grip are mounted to the backplate 523 of the device. An RCM linkage 525 connects the backplate 523 to an electrode insertion module connection plate 527. The electrode insertion module, including the electrode insertion motor 508 and the stylet insertion motor 509, are mounted to the electrode insertion module connection plate 527. The rotation motor 513 applies a force to the RCM linkage 525 cause the electrode insertion module connection plate 527 to pivot relative to the backplate 523. This pivoting causes the electrode insertion module to rotation about the remote center of motion 514.

[0036] Fig. 7 illustrates another example of an electrode array insertion device 701 that causes the electrode insertion module to rotate relative to a remote center of motion (RCM). The device of this example includes the dual-motor based insertion/sensory module 703 described in Fig. 4 above. The device 701 also includes a back cover with a fixed scissor grip handle 705 positioned opposite a control lever with an impedance motor for mechanical feedback 707. A RCM actuator 709 acts on an RCM tilt mechanism 711 to cause the insertion module to tilt relative to the scissor grip handle 707 and the backplate 705.

[0037] The RCM tilt mechanism 711 is a Watt-type linkage with a geometry that ensures rotation about a fixed axis in space. During insertion of the electrode array, the tool controls the tilting and insertion of the electrode array along with controlling the stylet pull. The actuation of the RCM tilt mechanism 711 is achieved through a worm-gear connection. The same worm-gear mechanism is also used for driving the moving arm of the scissor grip in order to provide force feedback to the user.

[0038] The insertion of the electrode push rod and the stylet pull rod are achieved using an actuated cross-roller bearing slide and a screw-nut pair that pulls the stylet and releases the gripper as illustrated in Fig. 8. The gripper holding the electrode array is a flex-gripper that is held closed by a spring-loaded collet. The user can release this gripper at any time by pushing the collet backward.

[0039] Fig. 9 illustrates an example of an electrode array insertion device that uses a three- degree of freedom parallel linkage to provide angle positioning of the insertion and sensory module. The device of Fig. 9 uses a circular actuation module and five motors. Three of the motors are positioned at the actuation module to achieve planar movement of the gripper. One motor operates the insertion modules. The fifth motor provides force feedback to the user through the control. The illustrated device uses 3R R parallel architecture with three planar kinematic chains having one active revolute joint at the based on the actuation module. Using a parallel linkage increases precision, reduces moving mass (since all motors are positioned in the base of the unit), and increased payload-to-weight ratio.

[0040] As mentioned above, the device of Fig. 9 uses only a single motor to operate the insertion/sensory module. Unlike the examples described above, the device of Fig. 9 includes only a motor to retract the stylet. It does not include a dedicated motor for inserting the electrode array using an electrode push rod. Instead, the electrode array is inserted using the parallel positioning mechanism. Actuation of the parallel positioning mechanisms is achieved through back-drivable meter gears that transmit motion from DC gear-motors. Fig. 10 provides an exploded view of the components of the device of Fig. 9.

[0041] Fig. 11 illustrates another example of an electrode insertion device using parallel linkages for inserting and controller the insertion angle of the electrode array. In this example, the three-Degree of Freedom planar movement of the parallel mechanism is achieved by replacing the 3RRR kinematic chains with wire-actuated extensible links. Each extensible link is actuated via a wire capstan that pulls on a miniature steel wire-rope. An internal spring prevents backlash. The wire rope is engaged to a drive pin that pushes/pulls the piston rod. In some alternative constructions, the wire rope routing can be simplified to an open loop wiring that allows only pulling against the force of the internal spring. This alternative wiring also provides a safety feature whereby the tool is deflected if the tool hits a hard object. Fig. 12 provides an exploded view of the device of Fig. 11.

[0042] Fig. 13 illustrates another electrode insertion device with a wire-actuated parallel linkage for controlling the insertion and angle of the electrode array. The device includes a two- degree of freedom planar mechanism and a wire-actuated tilting mechanism providing an additional degree of freedom. The device of Fig. 13 is lower weight compared to the devices described above.

[0043] Fig. 14 illustrates an example of an electrode insertion device including a wire- actuated parallel robot. The angle and position of the legs of the device are manipulated to control the angle and position of the insertion mechanism. The operation of the wire-actuated legs is shown schematically in Fig. 15. The actuation wire is brought directly to the motor assembly rather than being transmitted through a right angle miter gear. The wire tensioning device is located near the motor assembly and includes an idler pulley that can be translater linearly and secured once the appropriate tension is reached.

[0044] Fig. 16 illustrates the device of Fig. 14 from a top, side, and front perspective to further show the positioning of the legs relative to the sensory/insertion module of the device. Fig. 17 provides a cross-sectional view of the legs to illustrate the operation of the wire actuated pistons. Fig. 18 is an exploded view of one of the motor assemblies.

[0045] The illustrations of the various devices in Figs. 9-18 do not show a control mechanism such as the scissor grip or slide button integrated into the device housing, show the 1 and controller. In these examples, the control mechanisms can be integrated into the device housing as illustrated in Figs. 3-8. Alternatively, in some constructions, the control mechanism is provided in a separate housing such as illustrated, for example, in Fig. 19. In this example, the electrode insertion device is held in one hand while the control module is held in the other. The control device includes a plunger that is operated with the thumb. Impedance motor functions are included to provide the force feedback features described above. In other embodiments, the control module can be constructed as a foot-pedal to allow the surgeon to use his free hand for other operations.

[0046] Thus, the invention provides, among other things, a system for controlling the insertion of an electrode array coordinated with the retraction of a stylet from the electrode array. The device is operated using a control mechanism such as a plunger, a lever, or a slide button. The device detects mechanical resistance acting on the electrode array during insertion and provides tactile feedback to the user through the control mechanism. Various features and advantages of the invention are set forth in the following claims.

Claims

CLAIMS What is claimed is:

1. An electrode array insertion device comprising:

a control lever;

an electrode insertion stage that advances an electrode array relative to the electrode array insertion device in response to a mechanical manipulation applied to the control lever by a user;

a stylet puller stage to retract a stylet from the electrode array as the electrode array is advanced, the retraction of the stylet being coordinated with the advancement of the electrode in response to the mechanical manipulation applied to the control lever; a load sensor configured to detect a load applied to the electrode array as the electrode array is advanced; and

a controller configured to apply a feedback signal to the control lever based on the load detected by the load sensor, the feedback signal affecting the mechanical manipulation of the control lever.

2. The electrode array insertion device of claim 1, wherein the electrode insertion stage includes an electrode insertion rod and the stylet puller stage includes a stylet puller rod, wherein a distal end of the electrode insertion rod is configured to hold the electrode array, and wherein a distal end of the stylet puller rod is configured to hold the stylet.

3. The electrode array insertion device of claim 2, further comprising a first motor coupled to a proximal end of the electrode insert rod, and a second motor coupled to a proximal end of the stylet puller stage, wherein the first motor advances the electrode insertion rod based on the mechanical manipulation of the control lever, and wherein the second motor retracts the stylet puller rod based on the mechanical manipulation of the control lever.

4. The electrode array insertion device of claim 3, wherein the control lever includes a slide button electrically coupled to the first motor and the second motor, and wherein moving the slide button in a first direction causes advancement of the electrode insertion rod and retraction of the stylet puller rod.

5. The electrode array insertion device of claim 2, wherein a proximal end of the electrode insertion rod and a proximal end of the stylet puller rod are mechanically coupled to the control lever, and wherein, due to the mechanical coupling, movement of the control lever causes movement of both the electrode insertion rod and the stylet puller rod.

6. The electrode array insertion device of claim 1, further comprising an impedance motor that applies a resistance to the control lever based on the feedback signal from the controller, wherein the resistance restricts the movement of the control lever.

7. The electrode array insertion device of claim 1, wherein the control lever includes a scissor grip, and wherein closing the scissor grip causes advancement of the electrode insertion stage and retraction of the stylet puller stage.

8. The electrode array insertion device of claim 1, wherein the electrode insertion stage includes a parallel mechanism that advances the electrode array and adjusts an insertion angle of the electrode array relative to the electrode array insertion device.

9. The electrode array insertion device of claim 1, further comprising a tilting mechanism that adjusts an insertion angle of the electrode array relative to the electrode array insertion device.

10. The electrode array insertion device of claim 9, wherein the tilting mechanism causes the electrode insertion stage and the stylet puller stage to rotate relative to a remote center of movement external to the electrode array insertion device.

11. The electrode array insertion device of claim 9, wherein the controller is further configured to determine a position of the electrode array insertion device relative to the cochlea and adjust the insertion angle based on the relative position.

12. The electrode array insertion device of claim 9, wherein the tilting mechanism includes a Watt linkage.

13. A method of inserting an electrode array into a cochlea using an electrode array insertion device, the device including a control lever, an electrode insertion stage, and a stylet puller stage, the method comprising:

attaching the electrode array to the electrode insertion stage;

attaching a stylet associated with the electrode array to the stylet puller stage; detecting, by a controller, a movement of the control lever applied by a user; advancing the electrode insertion stage based on the movement of the control lever, wherein advancing the electrode insertion stage advances the electrode array into the cochlea;

retracting the stylet puller stage based on the movement of the control lever, wherein retracting the stylet puller stage retracts the stylet from the electrode array, and wherein the retraction of the stylet puller stage is coordinated with the advancement of the electrode insertion stage;

detecting, by the controller, a load applied to the electrode array as the electrode array is advanced into the cochlea; and

applying a feedback signal to the control lever based on the detected load, wherein the feedback signal mechanically affects operation of the control lever.