WO2017068383A1

WO2017068383A1 - Apparatus and methods for adjusting the curvature of cochlear implant electrode arrays

Info

Publication number: WO2017068383A1
Application number: PCT/IB2015/002106
Authority: WO
Inventors: Matt V. KRYWCUN; Uli Gommel
Original assignee: Advanced Bionics Ag
Priority date: 2015-10-23
Filing date: 2015-10-23
Publication date: 2017-04-27

Abstract

A forming fixture for use with a cochlear implant lead including an alteration section having a curved wall and a recess that secures the cochlear implant to the forming fixture such that the base end of the electrode array is adjacent to the curved wall.

Description

APPARATUS AND METHODS FOR ADJUSTING THE

CURVATURE OF COCHLEAR IMPLANT ELECTRODE ARRAYS

BACKGROUND

1 . Field

The present disclosure relates generally to the implantable portion of implantable cochlear stimulation (or "ICS") systems and, in particular, to the electrode arrays.

2. Description of the Related Art

ICS systems are used to help the profoundly deaf perceive a sensation of sound by directly exciting the intact auditory nerve with controlled impulses of electrical current. Ambient sound pressure waves are picked up by an externally worn microphone and converted to electrical signals. The electrical signals, in turn, are processed by a sound processor, converted to a pulse sequence having varying pulse widths and/or amplitudes, and transmitted to an implanted receiver circuit of the ICS system. The implanted receiver circuit is connected to an implantable lead with an electrode array that is inserted into the cochlea of the inner ear, and electrical stimulation current is applied to varying electrode combinations to create a perception of sound. The electrode array may, alternatively, be directly inserted into the cochlear nerve without residing in the cochlea. A representative ICS system is disclosed in U.S. Patent No. 5,824,022, which is entitled "Cochlear Stimulation System Employing Behind-The-Ear Sound processor With Remote Control" and incorporated herein by reference in its entirety. Examples of commercially available ICS sound processors include, but are not limited to, the Advanced Bionics™ Harmony™ BTE sound processor, the Advanced Bionics™ Naida™ BTE sound processor and the Advanced Bionics™ Neptune™ body worn sound processor.

One example of a conventional cochlear implant (or "implantable cochlear stimulator") is the cochlear implant 10 illustrated in FIGS. 1 -3. The cochlear implant 10 includes a flexible housing 12 formed from a silicone elastomer or other suitable material, a processor assembly 14, a cochlear lead 16 with an electrode array 18, and an antenna 20 that may be used to receive data and power by way of an external antenna that is associated with, for example, a sound processor unit. The electrode array 18 includes a flexible body 22 and a plurality of electrically conductive contacts 24 (e.g., the sixteen platinum contacts 24 illustrated in FIG. 3) spaced along the surface 25 of the flexible body. The contacts 24 may be referred by in numbered order, 1 ^st through 16^th, with the contact closest to the tip 40 being the 1^st contact and the contact closest to the base 41 being the 16^th contact. Once implanted, the electrodes 24 on the surface 25 face the modiolus within the cochlea. A positioning magnet 26 is located within a magnet pocket 28. The magnet 26 is used to maintain the position of a headpiece transmitter over the antenna 20. The cochlear implant may, in some instances, be configured is manner that facilitates magnet removal and replacement. Here, the housing 12 may be provided with a magnet aperture (not shown) that extends from the magnet pocket 28 to the exterior of the housing. Referring more specifically to FIG. 2, in addition to the electrode array 18, exemplary cochlear lead 16 includes a cochleostomy marker 30 and a wing 32, with a rectangular portion 34 and a tapered portion 36, which functions as a handle for the surgeon during the implantation surgery. A tubular member 38, which may consist of tubes of different sizes, extends from the wing 32 to the housing 12. The contacts 24 are connected to lead wires (not shown) that extend through the flexible body 22 and tubular member 38 to a connector (not shown) in the housing 12.

In many instances, it is desirable for the electrode array 18 to have a predefined curvature. An electrode array that does not have a curvature is more likely to engage anatomic structures within the cochlea during insertion which can, among other things, cause the tip of the electrode array to buckle. Too much curvature, on the other hand, can prevent the surgeon from being able to see the tip during insertion when the lead is held by the wing. The amount of curvature is sometimes evaluated based on tip deflection, i.e. the distance that the tip of the electrode array is offset from the tip of a straight electrode array.

During manufacture, the electrode array contacts 24 are welded to an iron strip and connected to the lead wires. The portions of the iron strip between the electrodes are removed by etching and the remaining components are then placed into a mold and resilient material, such as liquid silicone rubber ("LSR"), which forms the flexible body 22 and the wing 32 is injected into the mold in what is sometimes referred to as an overmolding process. Curved electrode arrays are formed in curved molds.

The present inventors have determined that conventional methods manufacturing curved electrode arrays are susceptive to improvement. Most notably, the present inventors have determined that the curvature of the completed array is frequently different that the curvature of the mold and that, for a given mold, the curvature of the electrode arrays may vary from one electrode array to another. As noted above, one way to measure the curvature of the electrode array 18 is to measure the tip deflection, i.e. the distance between where the tip 40 is and where it would have been if the electrode array was straight (as represented the location of the wing 32), in the manner illustrated in FIG. 2. Here, the length of the electrode array is 23 mm and the acceptable range is from deflection distance D1 (e.g., 2 mm) to deflection distance D2 (e.g., 5 mm) and, although the shape of the mold corresponded to the acceptable range, the actual tip deflection is greater than the acceptable range. The present inventors have determined that reasons for curvature variations include, but are not limited to, variations in the properties of the LSR material, wire tensioning, weld parameters, wire management, weld efficiency, contact folding, differences in the human operators, and differences in thickness of the LSR along the length of the array in the case of tapered arrays. As such, even when a useful mold curvature has been identified through a laborious trial and error process, many of the electrode arrays produced thereby will be outside of the acceptable tip deflection range.

SUMMARY

A forming fixture in accordance with one of the present inventions includes an alteration section having a curved wall defining an end and a recess that secures the cochlear implant to the forming fixture such that the base end of the electrode array is adjacent to the end of the curved wall.

A method in accordance with one of the present inventions includes the steps of placing the cochlear implant lead on a forming fixture that has a curved wall and adjusting the shape of the electrode array by pressing the electrode array against a portion of the curved wall on the forming fixture and then releasing the electrode array.

There are a number of advantages associated with such apparatus and methods. For example, the present apparatus and methods allow the curvature of molded electrode leads to be adjusted as necessary after they are removed from the mold.

The above described and many other features of the present inventions will become apparent as the inventions become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed descriptions of the exemplary embodiments will be made with reference to the accompanying drawings.

FIG. 1 is a plan view of a cochlear implant.

FIG. 2 is a side view of a portion of the cochlear lead illustrated in FIG. 1 . FIG. 3 is a bottom view of a portion of the cochlear lead illustrated in FIG.

1 .

FIG. 4 is perspective view of a forming fixture in accordance with one embodiment of a present invention.

FIG. 5 is a perspective view of a portion of the forming fixture illustrated in

FIG. 4.

FIG. 6 is a plan view of a portion of the forming fixture illustrated in FIG. 4.

FIG. 7 is an end view of the forming fixture illustrated in FIG. 4.

FIG. 8 is a plan view of a portion of the forming fixture illustrated in FIG. 4 and a cochlear implant lead positioned thereon prior to a curvature adjustment.

FIG. 9 is a plan view of a portion of the forming fixture illustrated in FIG.

4 and a cochlear implant lead positioned thereon during a curvature adjustment. FIG. 10 is a plan view of a portion of the forming fixture illustrated in FIG. 4 and a cochlear implant lead positioned thereon after a curvature adjustment.

FIG. 1 1 is a flow chart showing a method in accordance with one embodiment of a present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The following is a detailed description of the best presently known modes of carrying out the inventions. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the inventions.

One example of a cochlear lead forming fixture (or "forming fixture") in accordance with one of the present inventions is the forming fixture 100 illustrated in FIGS. 4-7. The forming fixture 100 may be used to determine whether or not the curvature of a molded cochlear lead electrode array is within the acceptable range and, if not, to alter the curvature of the molded electrode array so that it falls within the acceptable range. Although the present inventions are not so limited, the cochlear lead 16 illustrated in FIGS. 1 -3 is one example of a cochlear lead whose electrode array may be measured and adjusted with forming fixtures in accordance with the present inventions. The exemplary forming fixture 100 is configured for use with, among other cochlear leads, the cochlear lead 16 and references to particular lead structures will be made in the context of the cochlear lead 16. Depending on the configuration of the forming fixture and the orientation of the cochlear lead in the forming fixture, forming fixtures in accordance with the present inventions may be used to either reduce or increase the curvature of an electrode array.

Referring first to FIG. 4, the exemplary forming fixture 100 includes a support portion 102 that secures the wing 32 and tubular member 38, thereby preventing movement thereof when the electrode array 18 is on the fixture, and a working portion 104 where the curvature of the electrode array 18 is measured and, if necessary, reduced.

The support portion 102 of the exemplary forming fixture 100 has a slot 106, which extends inwardly from the upper surface 108, for the tubular member 38. The relatively thin and relatively wide portions 1 10 and 1 12 allow the slot 106 to accommodate the differently sized tubes of the tubular member 38. A recess 1 14 for the cochlear lead wing 32 is located adjacent to the slot 106. The recess 1 14 has rectangular and tapered portions 1 16 and 1 18 for the rectangular and tapered portions 34 and 36 of the wing 32, and defines a longitudinal axis LA (FIG. 6). The size and shape of the recess rectangular and tapered portions 1 16 and 1 18 closely correspond to those of the wing rectangular and tapered portions 34 and 36 to create and interference fit that firmly holds the wing in place, thereby securing the cochlear lead 16 to the forming fixture 100. An enlarged region 120 facilitates the use of a tool to remove the wing 32 from the recess 1 14.

The exemplary working portion 104 illustrated FIG. 4, which is discussed in greater detail below with reference to FIGS. 5-7, has a measurement section 122 and an alteration section 124. The measurement section 122 has an upper surface 126 and a pair of markers 128 and 130 that extend upwardly from the upper surface. The markers 128 and 130 are used by the technician to determine whether or not the curvature of an electrode array is within the allowable range. The alteration section 124 has an upper surface 132, a curved wall 134 that begins at the end of the recess 1 14 and extends upwardly from the upper surface, and a pair of markers 136 and 138. The markers 128 and 130 and the curved wall 134 are located on opposite sides of the longitudinal axis LA. The curvature of an electrode array may be adjusted by pressing it against the curved wall 134, and the markers 136 and 138 provide reference points that may be used by the technician during this process.

Turning to FIGS. 5-7, the configuration of the working portion 104 in the exemplary implementation is such that the electrode array will not come into contact with surfaces other than that of the curved wall 134 in those instances where the electrode array (e.g., electrode array 18) is stiff enough to prevent substantial deflection under its own weight. To that end, the electrode array wing will rest on the bottom surface 140 of the recess 1 14 when the cochlear lead is placed into the exemplary fixture 100 (FIG. 8). The distance D3 between the recess bottom surface 140 and the tops of the markers 128 and 130 is sufficient to prevent the electrode array from touching the tops of the markers, which could prevent accurate measurement. The distance D3 may range from 1 mm to 5 mm in some implementations, and is about 2.5 mm in the illustrated implementation. In alternate implementations where the markers on the measurement section upper surface 126 are flat, the distance between the measurement section upper surface 126 and the recess bottom surface 140 may be distance D3. With respect to the alteration section 124, the distance D4 between the upper surface 132 and the recess bottom surface 140 is sufficient to prevent the electrode array from touching the upper surface 132 while portions of the electrode array are being pressed against the curved wall 134 in the manner described below with reference to FIG. 9. If the electrode array were to drag along the upper surface 132 during this process, the electrode array could be twisted and damaged. The distance D4 may range from 0.5 mm to 5 mm in some implementations, and is about 1 mm in the illustrated implementation.

Referring more specifically to FIG. 6, the exemplary markers 128 and 130 in the measurement section 122 are configured in such a manner that the technician can determine, based on the observed location of the electrode array tip (or "tip deflection"), whether curvature is less than, within, or greater than the acceptable range. To that end, the marker 128 has an edge 128a whose location corresponds to the lower end of the acceptable deflection distance range, i.e. distance D1 , and the marker 130 has an edge 130a whose location corresponds to the upper end of the acceptable deflection distance range, i.e. distance D2. In one exemplary implementation where the distance D1 is 2 mm and the distance D2 is 5mm, the thickness of each of the marker 128 and 130 may be 1 mm and the spacing between the markers, i.e., the spacing between edges 128b and 130b, may also be 1 mm. As a result, deflection to edges 128b and 130b corresponds, respectively, to deflections of 3 mm and 4 mm and the technician will be able to more precisely determine the magnitude of tip deflections that are within the acceptable range.

Turning to the exemplary alteration section 124, the curved wall 134 has a curvature varies along its length and includes wall portions 142, 144, 146 and 148. The wall portion 142 is the portion closest to the recess 1 14 and defines an arc that is approximately 90°, the wall portions 144 and 148 are relatively flat, and the wall portion 146 has a slight curvature. When used in conjunction with the exemplary electrode array 18 (FIGS. 1 -3), marker 136 corresponds to the location of the 12^th contact when the array is pressed against the curved wall 134 and marker 138 corresponds to the location of the 8^th contact. The wall portion 148 is oriented relative to the other wall portions 144-146 in such a manner that it will not typically be used.

With respect to materials, suitable materials for the forming fixture 100 include, but are not limited to, Polyoxymethylene and Polyetherimide.

Referring to FIGS. 8-10, exemplary methods may include some or all of the following steps, which are described in the context of the exemplary cochlear lead 16. The electrode array 18 and wing 32 are molded and completely cured in the manner described above. The cochlear lead 16 is then secured to the exemplary forming fixture 100 by placing the wing 32 into the recess 1 14. The curvature of the electrode array 18, which is located above and spaced apart from the upper surfaces 126 and 132 and the markers 128 and 130, is then evaluated in an unstressed state based on the location of the tip 40 relative to the markers 128 and 130. In those instances where there is too much curvature, as is the case in FIG. 8, the curvature of the electrode array 18 will be adjusted by pressing portions of the electrode array against the curved wall 134 in, for example, the manner illustrated in FIG. 9.

Here, the electrode array 18 is pressed against the curved wall portions

142 and 144 up to the marker 136 with, for example, a tool 200. The tool 200 includes a relatively soft bulbous tip 202 that is carried on the end of a handle 204. The tool 200 may be oriented perpendicular to the surface 132 (or close to perpendicular) with bulbous tip 202 at the base 41 of the electrode array 18 adjacent to the wing 32, as is shown in dashed lines. The tool 200 is then used to sequentially press portions of the electrode array against the wall portions 142 and 144 until the bulbous tip 202 reaches the marker 136, as is shown in solid lines. The bulbous tip 202 may be advanced along the electrode array 18 by rotating the tool 200 in the direction of arrow A while applying the force that presses the electrode array against the curved wall 134. The portion of the electrode array 18 between the wing 32 and the marker 136 will bend in the manner illustrated in FIG. 9, while the remainder of the electrode array 18 generally holds its shape. The electrode array 18 may held against the curved wall 134 for a period of, for example, 5-10 seconds after reaching the marker 136.

The force being electrode array 18 is then removed to allow the electrode array return to an unstressed state. Although the technician could simply pull the tool 200 away from the electrode array 18 in a direction perpendicular to the upper surface 132, it is preferred that the force be removed in a less abrupt manner. For example, the bulbous tip 202 may be moved along the electrode array 18 from the marker 136 to dash line position on the base 41 of the electrode array adjacent to wing 32. This may be accomplished by, for example, rotating the tool 200 in a direction opposite arrow A while continuing to apply the force that presses the electrode array 18 against the curved wall 134. Alternatively, the tool 200 may be moved in a controlled manner toward the markers 128 and 130 until bulbous tip 202 separates from the electrode array 18. Once released from the tool 200 (or other suitable device), the electrode array 18 will assume an adjusted, less curved shape due to the properties of the LSR or other material that forms the flexible body 22, the internal metal wires and the contacts 24.

Next, as illustrated in FIG. 10, the adjusted electrode array 18 may be reevaluated based on the location of the tip 40 relative to the markers 128 and 130. In those instances where the curvature is within the acceptable range, as it is in FIG. 10, the completed cochlear lead 16 may be removed from the fixture 100. If, one the other hand, the electrode array 18 continues to have too much curvature (albeit less than that illustrated in FIG. 8), the curvature of the electrode array 18 will be adjusted again by pressing portions of the electrode array against the curved wall 134 in a manner similar to that described above with reference to FIG. 9. Here, however, the electrode array 18 is pressed against the curved wall portions 142-146 up to the marker 138 with the tool 200. After a period of, for example, 5-10 seconds, the electrode array 18 may then be released in the manner described above and re-evaluated. If there is still too much curvature, this process may be repeated a few more times before the electrode array is discarded.

It should be noted that the cochlear lead forming fixture and associated methods are not limited to those described above. By way of example, but not limitation, a cochlear lead forming fixture may be configured for use with electrode arrays that are produced and fully cured in a straight mold. Here, a curved wall similar to curved wall 134 (with a different shape) will be located on the same side of the recess 1 14 as the markers 128 and 130. Such a fixture may be used to add curvature to an electrode array by pressing the straight electrode array against the curved wall in a manner similar to that described above. After the electrode array is released, the curvature can be evaluated based on the tip deflection. The cochlear lead may be removed from the fixture if the curvature is within the acceptable range. If the curvature not yet within the acceptable range, the electrode array may be pressed farther along the curved wall, released, re-evaluated, and then removed from the forming fixture if within the acceptable curvature range.

In some instances, the electrode array may be only partially cured (e.g., 80% cured) in the straight mold prior to being placed into a forming fixture. After the forming fixture has been used in the manner described above to obtain the desired curvature, the electrode array may be inserted into a curved mold that has desired curvature (or simply left on the forming fixture) and placed into an oven to complete the curing process.

The various methods described above are summarized in the flow chart illustrated in FIG. 1 1 . After the cochlear lead has been inserted into the fixture (Step S01 ), the technician will determine whether or not the curvature of the electrode array is within the acceptable range (Step S02). If the curvature is within the acceptable range, the cochlear lead may be removed from the fixture (Step S03). If not, the electrode array may be pressed against a curved wall of the fixture (Step S04) and, after the electrode is released, the curvature may be re-evaluated (Step S05). If the curvature is within the acceptable range, the cochlear lead may be removed from the fixture (Step S06). If not, the electrode array may be pressed farther along the curved wall (Step S07), released, reevaluated, and then removed from the forming fixture (S08) if within the acceptable curvature range. In some instances, Steps S04 to S07 may be repeated a few times prior to removing lead from the fixture (Step S08).

Although the inventions disclosed herein have been described in terms of the preferred embodiments above, numerous modifications and/or additions to the above-described preferred embodiments would be readily apparent to one skilled in the art. By way of example, but not limitation, the inventions include any combination of the elements from the various species and embodiments disclosed in the specification that are not already described. It is intended that the scope of the present inventions extend to all such modifications and/or additions and that the scope of the present inventions is limited solely by the claims set forth below.

Claims

We claim:

1 . A forming fixture for use with a cochlear implant lead having an electrode array with a base end, a tip end, and a plurality of contacts, the forming fixture comprising:

an alteration section having a curved wall defining an end; and a recess that secures the cochlear implant to the forming fixture such that the base end of the electrode array is adjacent to the end of the curved wall.

2. A forming fixture as claimed in claim 1 , wherein

the alteration section includes an upper surface and the curved wall extends upwardly from the upper surface; and

the recess includes a bottom surface that is located above the upper surface of the alteration section.

3. A forming fixture as claimed in claim 1 , wherein

the curved wall has at least two portions with different curvatures.

4. A forming fixture as claimed in claim 1 , further comprising:

at least one marker adjacent to the curved wall.

5. A forming fixture as claimed in claim 1 ,

wherein the recess includes a bottom surface and defines a longitudinal axis; and

the forming fixture further comprises a measurement section having at least one marker that is offset from the longitudinal axis and is located below the bottom surface of the recess.

6. A forming fixture as claimed in claim 5, wherein the curved wall and the at least one marker are located on opposite sides of the longitudinal axis.

7. A forming fixture as claimed in claim 5, wherein

the measurement section includes an upper surface; and the at least one marker comprise a pair of markers that extend upwardly from the upper surface of the measurement section and are offset from the longitudinal axis by different distances.

8. A forming fixture, comprising:

an alteration section having a curved wall defining an end; and means for securing a cochlear implant lead, which has an electrode array with a base end, a tip end, and a plurality of contacts, to the forming fixture such that the base end of the electrode array is adjacent to the end of the curved wall.

9. A forming fixture as claimed in claim 8, wherein

the means for securing the cochlear implant lead secure the cochlear implant lead to the to the forming fixture such that the electrode array is spaced apart from the upper surface of the alteration section.

10. A forming fixture as claimed in claim 8, wherein

the curved wall has at least two portions with different curvatures.

1 1 . A forming fixture as claimed in claim 8, further comprising:

at least one marker adjacent to the curved wall.

12. A forming fixture as claimed in claim 8, further comprising:

a measurement section having an upper surface with at least one marker; wherein the means for securing the cochlear implant lead secure the cochlear implant lead to the to the forming fixture such that the electrode array is spaced apart from the at least one marker and the tip end is located over the measurement section.

13. A forming fixture as claimed in claim 12, wherein

the curved wall and the at least one marker are located on opposite sides of the means for securing the cochlear implant lead.

14. A method for use with a cochlear implant lead having an electrode array with a base end, a tip end, and a plurality of contacts, the method comprising the steps of:

placing the cochlear implant lead on a forming fixture that has a curved wall; and

adjusting the shape of the electrode array by pressing the electrode array against a portion of the curved wall on the forming fixture and then releasing the electrode array.

15. A method as claimed in claim 14, wherein

the electrode array comprises a curved electrode array;

the forming fixture includes a measurement section having an upper surface with at least one marker; and

the step of placing the cochlear implant lead comprises placing the cochlear implant lead on the forming fixture such that the tip is located over the measurement section and is spaced apart from the measurement section.

16. A method as claimed in claim 15, further comprising the step of: prior to the adjusting step, determining whether or not the electrode array is within a predetermined curvature range based on the location of the tip relative to the at least one marker.

17. A method as claimed in claim 15, further comprising the step of: after the adjusting step, determining whether or not the electrode array is within a predetermined curvature range based on the location of the tip relative to the at least one marker.

18. A method as claimed in claim 17, further comprising the step of: removing the cochlear implant lead from the forming fixture in response to the electrode array being within the predetermined curvature range.

19. A method as claimed in claim 17, further comprising the step of: further adjusting the shape of the electrode array by pressing the electrode array against a larger portion of the curved wall on the forming fixture and then releasing the electrode array in response to the electrode array no being within the predetermined curvature range.

20. A method as claimed in claim 14, further comprising the step of: fully curing the electrode array prior to placing the electrode lead into the forming fixture.