US007891085B1
`
`(12) United States Patent
`Kuzma et a].
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,891,085 B1
`Feb. 22, 2011
`
`(54) ELECTRODE ARRAY ASSEMBLY AND
`METHOD OF MAKING SAME
`
`5,555,618 A *
`6,055,456 A
`6,205,361 B1
`
`9/1996 Winkler ..................... .. 29/825
`4/2000 Gerber
`3/2001 Kuzma et al.
`
`
`
`Inventors: JanusZA Kuzmaa Parker’ Anne M Pianca’ Valencia’ CA (Us)
`
`
`
`* 6,249,708 B1 *
`
`
`
`Black et al. . . . . . . . . . . . . . . . .. 6/2001 Nelson et al.
`
`607/122
`
`6,551,302 B1 *
`
`4/2003 Rosinko et al.
`
`604/505
`
`(73) Assigneez Boston scienti?c Neuromodulation
`
`2005/0215945 A1* 9/2005 Harris et a1. . . . . . .
`
`. . . .. 604/66
`
`Corporation, Valencia, CA (US)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U_S_C_ 154(b) by 639 days'
`
`(21) Appl. No.: 11/329,907
`
`(22) Filed:
`
`Jan. 11, 2006
`
`Related US. Application Data
`(60) Provisional application No. 60/ 643,093, ?led on Jan.
`11 2005'
`’
`(51) Int_ CL
`(200601)
`H0 1 R 43/00
`(200601)
`A 61N 1/00
`(52) us. Cl. ....................................... .. 29/825' 607/116
`(58) Field of Classi?cation Search
`’ 29/825
`/1 1 5*122’
`""""""
`h h. t
`1 t
`?l f
`t.
`1.
`S
`ee app 10a Ion e or Comp e e Seam Is my
`References Cited
`
`(56)
`
`US. PATENT DOCUMENTS
`
`3,769,984 A 11/1973 Muench
`
`* cited by examiner
`_
`_
`Prlmary ExamllaeriA' Dexter Tugbang
`Asststant ExammeriDavid P AngWm
`(74) Attorney, Agent, or F zrmiFrommer Lawrence & Haug
`LLP; B11199 E- Black
`
`(57)
`
`ABSTRACT
`
`A lead assembly and a method of making a lead are provided.
`The method 9f making a.multi_comact lead assembly Com
`pnses prov1d1ng conductlve contacts located at an end of a
`lead body, disposing conductive Wires in conductor lumens
`formed in the lead body, and connecting the conductive Wires
`to the conductive contacts. The method further includes plac
`ing spacers between pairs of conductive contacts and insert
`mg mono?lamem “1 a‘ least? port1on of a‘ least 01.16 Ofthe
`conductor lumens not occupied by the conductor W1res. The
`method also ln'cludes re?oWmg at least one of the spacers or
`mono?lament 1nto at least one port1on of at least one of the
`conductor lumens by heating the spacers andmono?lament to
`a temperature to cause thermal ?oW or melting of at least one
`of the spacers or mono?lament.
`
`19 Claims, 5 Drawing Sheets
`
`Nevro Corp.
`Ex. 1001
`U.S. Patent No. 7,891,085
`
`

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`US. Patent
`US. Patent
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`Feb. 22, 2011
`Feb. 22, 2011
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`Sheet 1 015
`Sheet 1 of5
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`US 7,891,085 B1
`US 7,891,085 B1
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`US. Patent
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`Feb. 22, 2011
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`Sheet 2 of5
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`US 7,891,085 B1
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`US. Patent
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`Feb. 22, 2011
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`Sheet 3 of5
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`US 7,891,085 B1
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`WELDING DETAIL PROXIMAL END
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`US. Patent
`US. Patent
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`Feb. 22, 2011
`Feb. 22, 2011
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`Sheet 4 of5
`Sheet 4 of5
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`US 7,891,085 B1
`US 7,891,085 B1
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`US. Patent
`US. Patent
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`Feb. 22, 2011
`Feb. 22, 2011
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`US 7,891,085 B1
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`US 7,891,085 B1
`
`1
`ELECTRODE ARRAY ASSEMBLY AND
`METHOD OF MAKING SAME
`
`2
`improve the design of a percutaneous lead in order to improve
`its performance and to improve the method of manufacturing
`the lead.
`
`The present application claims the bene?t of US. Provi
`sional Patent Application Ser. No. 60/643,093, ?led Jan. 11,
`2005, Which application is herein incorporated by reference
`in its entirety.
`
`FIELD OF THE INVENTION
`
`The present invention relates to implantable leads for pro
`viding electrical stimulation and, more particularly, relates to
`leads having multiple electrode contacts and methods of mak
`ing such leads.
`
`BACKGROUND
`
`Many types of implantable leads are currently used to treat
`a variety of maladies. TWo common treatment applications
`use leads having multiple electrode contacts. Cochlear stimu
`lator systems use a multiple electrode contact lead inserted
`into one of the cochlear chambers to stimulate the cochlear
`nerve. Another application Where a multiple electrode contact
`lead is used is the treatment of chronic pain through stimula
`tion of the spinal cord.
`Spinal cord stimulation systems generally have tWo
`implantable components: an implantable pulse generator
`(IPG) and at least one lead connected to one output of the IPG.
`Generally, hoWever, the IPG is a multi-channel device
`capable of delivering electrical current through the electrode
`contacts of the lead. The term “lead” used herein Will refer to
`an elongate device having any conductor or conductors, cov
`ered With an insulated sheath and having at least one electrode
`contact attached to the elongate device, usually at the distal
`portion of the elongate device. The lead can have an inner
`stylet lumen running through most of the length of the lead
`and Which lumen has an opening at the proximal end of the
`lead. A stylet may be placed into this stylet lumen during
`steering and implantation of the lead. The inserted stylet in the
`lumen can help stiffen the lead so that the stylet/lead combi
`nation may be more easily inserted through tissue.
`There are tWo types of leads that may be used With the IPG.
`The ?rst type is a paddle lead, Which has a multiplicity of
`electrode contacts spread out over a ?at, paddle-like surface
`that is attached to one end of the lead. A paddle lead advan
`tageously permits the electrode contacts to be spaced apart to
`provide Wide coverage over a stimulation area. A disadvan
`tage presented With a paddle lead is that it usually requires a
`laminectomy or laminotomy, Which are highly invasive sur
`gical procedures necessary to implant the large, non-isodia
`metric paddle.
`A second type of lead that is commonly used is a percuta
`neous lead, Which has multiple electrode contacts positioned
`along the distal portion of an elongate lead. US. Pat. No.
`6,205,361 issued to Baudino et al. describes the making of a
`multi-contact electrode array for a lead. The distal end of the
`lead may be about the same thickness or diameter as the
`remainder of the lead. The percutaneous lead is dimension
`ally con?gured for tunneling to a target stimulation site. No
`invasive surgical procedure such as a laminotomy is required;
`the percutaneous lead may be placed through an epidural type
`needle reducing surgical trauma.
`The method of making a multi-contact percutaneous lead
`can be involved. In general, it is desirable to make the lead
`e?iciently, With the feWest number of process steps, maxi
`miZe the manufacturing yield, and hence reduce the cost of
`goods of building the leads. There is thus a continual need to
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`BRIEF SUMMARY
`
`A method of making a lead is provided. In one embodiment
`of the invention the method comprises: providing a plurality
`of conductive contacts located at the distal end of the stimu
`lation lead; connecting a conductor Wire to each of the con
`ductive contacts; placing spacers betWeen pairs of adjacent
`conductive contacts; placing mono?lament Within void
`spaces not occupied by a conductor Wire, Wherein the
`mono?lament is the same material as the spacers; placing a
`heat shrink tubing around the spacers, conductive contacts
`and mono?lament; and heating the spacers and mono?lament
`just beloW the melting temperature to cause thermal fusion
`betWeen the mono?lament and spacer.
`The conductive contacts may be connector contacts located
`at the proximal portion of the lead, Which contacts are used to
`connect to the IPG, or the conductive contacts may be elec
`trode contacts located someWhere on the lead (e.g., usually at
`the distal end of the lead).
`In another embodiment of the method of making the lead,
`the method comprises: providing a plurality of conductive
`contacts located at the proximal end of the stimulation lead;
`connecting a conductor Wire to each of the conductive con
`tacts; placing spacers betWeen pairs of adjacent conductive
`contacts; placing mono?lament Within void spaces not occu
`pied by a conductor Wire, Wherein the mono?lament is a
`different material than the spacers; placing a heat shrink
`tubing around the spacers, conductive contacts, and
`mono?lament; and heating the spacers and mono?lament to a
`temperature to cause thermal ?oW or melting of at least one of
`the spacers or mono?lament.
`Hence, While the mono?lament and spacers may be the
`same material With the same melting temperatures, that is an
`optional part of the invention. The mono?lament and spacers
`may actually be different materials, e.g., a type of thermo
`plastic polyurethane mono?lament and another type thermo
`plastic polyurethane spacer, With different hardness and melt
`ing points in order to yield a particular stiffness.
`In an embodiment of the invention, a lead assembly is
`provided comprising: a plurality of electrically conductive
`contacts; spacers placed betWeen each adjacent contacts; a
`conductor Wire connected to each conductive contact; and
`mono?lament placed into void spaces not occupied by con
`ductor Wire, Wherein the mono?lament is made from the same
`insulative material as the spacer; and Wherein the spacer and
`mono?lament are thermally fused from heat applied to the
`lead assembly, Which heat is just beloW the melting tempera
`ture of the spacer and the mono?lament material.
`In yet another embodiment, a lead assembly is provided
`comprising: a plurality of electrically conductive contacts;
`spacers placed betWeen each adjacent contacts; a conductor
`Wire connected to each conductive contact; and mono?lament
`placed into void spaces not occupied by conductor Wire,
`Wherein the mono?lament is made from a different insulative
`material as the spacer; and Wherein the spacer and mono?la
`ment are heated to a temperature to cause either the spacer or
`mono?lament material to thermally re?oW or melt.
`The mono?lament and spacer may be the same thermo
`plastic material to have the same melting point and to thereby
`alloW thermal fusion upon heating at a temperature just beloW
`the melting temperature of the material or the mono?lament
`and spacer may have different melting points.
`
`

`

`US 7,891,085 B1
`
`3
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The above and other aspects of the present invention will be
`more apparent from the following more particular description
`thereof, presented in conjunction with the following drawings
`wherein:
`FIG. 1 shows a generaliZed spinal cord stimulation system
`with a percutaneous lead connected to an implantable pulse
`generator (“IPG”);
`FIG. 2 shows an illustration of the percutaneous lead
`implanted into the epidural space of a human spinal cord;
`FIG. 3A shows a side view of the distal end of a percuta
`neous lead.
`FIG. 3B shows a side view of the proximal (connector) end
`of the percutaneous lead shown in FIG. 3A;
`FIG. 4 shows a view of the proximal end of the lead assem
`bly showing the connector contacts and conductor wires that
`connect to each connector contact;
`FIG. 5A shows a cross-sectional view of the percutaneous
`lead shown in FIG. 3A at line 5A-5A;
`FIG. 5B shows a cross-sectional view of the percutaneous
`lead shown in FIG. 5A along line 5B-5B;
`FIG. 5C shows a perspective view of the lead body, having
`a central stylet lumen and surrounding smaller lumens for
`containing conductor wires;
`FIG. 6A shows a close-up, partial, longitudinal view of the
`lead assembly at the distal portion of the lead; and
`FIG. 6B depicts how polyurethane mono?lament or a ther
`moplastic material is used to ?ll the voids and is incorporated
`into the lead by applying heat.
`Corresponding reference characters indicate correspond
`ing components throughout the several views of the drawings.
`
`DETAILED DESCRIPTION OF THE INVENTION
`
`The following description is of the best mode presently
`contemplated for carrying out the invention. This description
`is not to be taken in a limiting sense, but is made merely for the
`purpose of describing the general principles of the invention.
`The scope of the invention should be determined with refer
`ence to the claims.
`FIG. 1 shows a generaliZed stimulation system that may be
`used in spinal cord stimulation (SCS), as well as other stimu
`lation applications. Such a system typically comprises an
`implantable pulse generator (“IPG”) 12, an optional lead
`extension 14, a lead 16 and an electrode array 18. The elec
`trode array 18 includes a plurality of electrode contacts 17. In
`a percutaneous lead, the electrode contacts 17 canbe arranged
`in an in-line electrode array 18 at the distal end of the lead 16.
`Other electrode array con?gurations can also be used. The
`IPG 12 generates stimulation current pulses that are applied
`to selected electrode contacts 17 within the electrode array
`18.
`The proximal end of the lead extension 14 can be remov
`ably connected to the IPG 12 and a distal end of the lead
`extension 14 can be removably connected to a proximal end
`of the lead 16. The electrode array 18 is formed on a distal end
`of the lead 16. The in-series combination of the lead extension
`14 and lead 16 conduct the stimulation current from the IPG
`12 to electrode contacts 17 of the electrode array 18. It is
`noted that the lead extension 14 need not always be used with
`the neural stimulation system 10. Instead, the lead extension
`14 may be used when the physical distance between the IPG
`12 and the electrode array 18 requires its use, or for the
`purpose of a temporary trial procedure.
`The IPG 12 contains electrical circuitry, powered by an
`internal primary (one-time-use-only) or a rechargeable bat
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`tery, which through the use of electrical circuitry can output
`current pulses to each stimulation channel. Communication
`with the IPG can be accomplished using an external program
`mer (not shown), typically through a radio-frequency (RF)
`link.
`FIG. 2 shows a transverse, mid-sagittal view of a spinal
`cord and a generaliZed, implantable, spinal cord stimulation
`system. The stimulation system shown is being used as a
`spinal cord stimulator (SCS) system. In such an application,
`the lead 16 and, more particularly, the electrode array 18 are
`implanted in the epidural space 20 of a patient in close prox
`imity to the spinal cord 19. Because of the lack of space near
`the lead exit point 15 where the electrode lead 16 exits the
`spinal column, the IPG 12 may be implanted in the abdomen
`or above the buttocks. Use of lead extension 14 facilitates
`locating the IPG 12 away from the lead exit point 15.
`FIG. 3A shows, in accordance with the invention, a distal
`portion of a percutaneous stimulating lead 16. The stimulat
`ing lead 16 is used to stimulate neural tissue by delivering
`electrical stimulus pulses through at least one of the electrode
`contacts 17. The electrode contacts 17 can be separated by
`electrode contact spacers (or an insulative material) 61 that
`insulate the electrode contacts 17 from each other. A radio
`paque marker 30 located at the distal tip of the lead 16 may be
`optionally included. Alternatively, the tip of the lead may be
`the same material as the remainder of the lead insulation. The
`IPG 12 may be con?gured to permit connection to the two
`stimulating leads, each having eight electrode contacts 17. A
`pair of stimulating leads 16 may be connected to an IPG 12
`and an electrical circuit may be created between one electrode
`contact on the ?rst lead and another electrode contact located
`on the second lead. The IPG 12, for example, may have
`sixteen independently programmable outputs that allow pro
`gramming of pulse amplitude, pulse width and frequency of
`the pulse width. The electrode contacts 17 are to be made of
`a bio-compatible, electrically conductive electrode material
`such as platinum/ iridium alloy, platinum, titanium or the like.
`As an example, the stimulating lead 16 may have a diam
`eter of between about 0.03 to 0.07 inches for spinal cord
`stimulation applications. An insertion cannula (not shown),
`e.g., a 14 gauge insertion needle may be used, while a 0.05
`inch diameter stimulating lead is inserted within the cannula
`to help implant the stimulating lead 16. The stimulating lead
`16 may come in a variety of lengths, e.g., 30, 50, 70 and 90
`cm. A practitioner can extend the length of any of the avail
`able lead lengths by opting to use an extension lead 14 (shown
`in FIG. 1). The proximal male end of the extension lead 14
`should be con?gured to be insertable into the lead connector
`of the IPG and the distal female end of the extension lead
`should be con?gured to accept the proximal connector end of
`the stimulating lead 16.
`FIG. 3B shows, in accordance with the invention, a depic
`tion of the proximal end of the lead 16. This proximal lead
`end, including the eight, electrically conductive, connector
`contacts 40, and a contact tip element 41, collectively will be
`called herein as the proximal lead connector end 42 of the
`stimulating lead 16. Connector contact spacers 45 are placed
`between the connector contacts 40. The spacers 45 may be
`made from an implantable grade polyurethane such as Pelle
`thane® 55D thermoplastic material. The contacts 40 may be
`made from a non-corrosive, electrically conductive material,
`e.g., platinum/ iridium alloy or platinum. Contact tip 41, how
`ever, is not electrically connected to any conductor and con
`tact tip 41 may merely serve as a hard surface for a mechanical
`contact securing device, such as a set screw, which may be
`used to secure the lead connector end 42 with the connector
`block of the IPG 12. Contact tip 41 is optional and does not
`
`

`

`US 7,891,085 B1
`
`5
`need to be included as part of the lead. Instead, the contact tip
`of the lead may be of similar or the same insulation material
`as the remainder of the lead 16 or lead body 110 (FIG. 5C).
`Preferably the lead 16 is substantially isodiametric, mean
`ing that the diameter along the lead’ s entire length is equal or
`nearly equal. However, the lead 16 does not need to be iso
`diametric. For example, the connector contacts 40 at the
`proximal end may be larger (oversiZed) or smaller in diameter
`compared to the remainder of the lead 16 or lead body 110
`(shoWn in FIG. 5C). Likewise, the electrode contacts 17 may
`be larger (oversiZed) or smaller in diameter compared to the
`remainder of the lead 16 or lead body 110 (shoWn in FIG. 5C).
`FIG. 4 shoWs a proximal lead assembly With each of the
`connector contacts 40 Welded to a respective one of conduc
`tors 122. Each of the eight connector contacts 40, as shoWn,
`are connected to a conductor 122 Which, in turn, are con
`nected to a respective electrode contact 17 at the distal end of
`the stimulating lead 16. The insulating material betWeen the
`connector contacts 40 and around the conductors 122 is not
`shoWn in FIG. 4 for purposes of better illustrating the con
`nection betWeen each conductor and its respective connector
`contact. The connection may be a Weld. Cylindrical element
`46 is optional and is not connected to any conductor. Cylin
`drical element 46 may be used as a contact element for a
`mechanical securing device such as a set screW in order to
`secure the lead 16 to the IPG 12. Alternatively, or in addition,
`the cylindrical element 46 may function as a radiopaque
`element, provided that the material used for element 46 is
`radiopaque.
`FIG. 5A shoWs a cross-sectional vieW of the lead of FIG.
`3A along line 5A-5A.
`FIG. 5B shoWs a partial, cross-sectional vieW of the lead
`along the line 5B-5B.
`FIG. 5C shoWs a perspective vieW of an exemplary lead
`body 110 of the lead 16, excluding conductor Wires. The lead
`body is that portion of the lead insulation 112 that is betWeen
`the distal electrode contact array 18 and the array of connec
`tors contacts 40 (FIG. 4) at the proximal lead connector end
`42. The lead body 110 may be extruded as a one-piece com
`ponent. Note the central stylet lumen 114 and the surrounding
`eight conductor lumens 116.
`FIGS. 5A and 5B shoW an exemplary embodiment of an
`insulation section 112 of the lead body 110 having eight
`lumens 116 containing the conductor (Wires) 122, having
`individual strands 120. For example 15 or 16 individual con
`ductor strands 120 may be braided or bundled into a single
`conductor 122. Also shoWn is a central lumen 114 that may be
`used to accept an insertion stylet (not shoWn) Within the
`lumen to facilitate lead implantation. The opening of the
`lumen occurs at the proximal end of the lead 16. The lead
`body 110 may be a biocompatible, insulating lead material.
`Preferably the lead body 110 is made from a polyurethane. In
`particular the material may be Pellethane® thermoplastic
`material, eg 55D, 65D, or other durometer hardness. As
`previously indicated for FIG. 5C, the lead body 110 shoWn in
`FIG. 5B may be extruded as one piece.
`FIG. 6A shoWs a partial vieW of a longitudinal, cross
`section at the distal end of the lead, in accordance With an
`embodiment of the invention. FIG. 6A shoWs a ring-like
`electrode contact 17 (Which may be platinum, for example),
`multi-stranded conductor 122 and electrode contact spacer 61
`(or an insulative material). The spacer 61, Which is ring-like in
`con?guration, may be made of polyurethane insulative mate
`rial, e.g., Pellethane®. Mono?lament 60, also may be made of
`thermoplastic Pellethane® material or other insulation mate
`rial, e.g., polyester. During manufacture, the mono?lament
`60 may be inserted into the void spaces that are not ?lled by
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`the conductor 50. A heat shrink tube 65 is also shoWn placed
`around the electrode contacts 17 and conductor 122 assembly.
`The heat shrink tube 65 may be PTFE (e. g., Te?on® material)
`or a polyester heat shrink material. The heat shrink tube can
`be used during manufacturing and is not part of the stimula
`tion lead.
`FIG. 6B shoWs a tWo-frame, time-elapsed illustration of a
`partial vieW of the distal end of the lead as in FIG. 6A shoWing
`the conductor 122 connected (e.g., Welded) to the electrode
`contact 17. The ?rst frame (i) of FIG. 6B shoWs the sequence
`in Which the mono?lament 60 ?lls a large part of the void
`space 70. The part of the lead assembly shoWn is then placed
`into a heat, for example, at 190 degrees Celsius for a period of
`30 seconds. The heat that may be used, e.g., for polyurethane
`material (such as Pellethane®), may range from about 140 to
`250 degrees Celsius for a period of about between 15 to 120
`seconds. HoWever, importantly, the heat applied to the spacer
`and mono?lament material, should be just beloW the melting
`temperature of the material. At this just-beloW-melting tem
`perature, the spacer and mono?lament Will re?oW and ther
`mally fuse together as shoWn in the second frame (ii). The
`spacer 61 and the mono?lament 60 may be exactly the same
`material With the same melting temperature in order to facili
`tate thermal fusion. For example, the material may be the
`same implantable grade polyurethane such as Pellethane 55D
`or 75D.
`Altematively, hoWever, the mono?lament may be of a dif
`ferent material than the spacer to alter the mechanical char
`acteristic of the ?nal lead assembly. The mono?lament and
`spacer may have different melting points or very close melt
`ing points. The mono?lament and spacers may be the same
`type of material but With different formulations, e.g., to pro
`vide different hardness. For example, the mono?lament may
`be a 55D (durometer hardness) material and the spacer may
`be a 75D material. The predetermined temperature chosen to
`heat both the mono?lament and spacers should cause at least
`one of the materials used to thermally re?oW or, alternatively
`to melt. In some cases, the temperature may be chosen that
`one material melts While the other material thermally re?oWs.
`While FIGS. 6A and 6B shoW the distal end of the lead, the
`same process of using a mono?lament to ?ll up void spaces
`may be used at the proximal end of the lead assembly. At the
`proximal end of the lead assembly, the conductive contacts
`are not electrode contacts but, are instead, electrically con
`ductive connector contacts 40 that must be in electrical con
`nection With complementary contacts in the IPG connector.
`The connector contact spacers 45 at the proximal end of the
`lead (shoWn in FIG. 3B) are placed betWeen adjacent connec
`tor contacts 40. In one embodiment of the invention, the
`connector contact spacers 45 may be oversiZedithat is, the
`spacers may have an initial diameter that is larger than the
`?nal lead diameter. The proximal connector end of the lead
`assembly 42 may then be heated to a temperature (just beloW
`melting point of the spacer and mono?lament) for a duration
`of time previously described in order to produce thermal
`fusion of the connector contact spacer 45 and mono?lament
`60 to create a continuous re?oW of material betWeen the
`spaces not occupied by the connector contacts 40 and con
`ductor Wires 122.
`Alternatively, the mono?lament 60 and spacer 45 may be
`different materials With different melting points or about the
`same melting points.
`Hence, the method of placing mono?lament into void
`spaces not occupied by the conductor 122, may be used solely
`at the distal end of a lead, solely at the proximal end of a lead,
`or may be employed concurrently at both ends of a lead. If
`only one end of a lead employs mono?lament, the other end
`
`

`

`US 7,891,085 B1
`
`7
`of the lead may employ another method to ?nish the build,
`e.g., over'molding using a mold or injecting material such as
`epoxy, e.g., Hysol® into the void spaces betWeen the contacts
`and conductor Wires.
`
`Example
`
`The following steps illustrates one example embodiment
`of a method for making the lead, in accordance With the
`invention. Embodiments of the method can include one or
`more of the folloWing steps (although not necessarily in the
`order presented). (1) A braided or bundled, insulated, multi
`?lament conductor, e.g., having 2-200 ?laments, can be
`ablated of insulation at one end to expose the conductor. (2)
`The exposed end of the conductor can be Welded to an elec
`trode contact (located on the distal end lead assembly). (3)
`OversiZed, distal lead spacers may be placed betWeen the
`electrode contacts. (4) The multi-lumen tube (lead body) may
`be pre-cut With ablated section located at the distal and proxi
`mal ends. (5) Each end of the conductor cable can be inserted
`through the corresponding conductor lumens in the lead body.
`(6) The oversiZed spacers can be placed betWeen each ring
`like electrode contact at the distal end of the lead assembly;
`the spacers 61 may be “oversiZed”, meaning that they may
`have a diameter greater than the lead body 110 and in addi
`tion, the diameter of the electrode contacts 17 may be over
`siZed compared to the diameter of the lead body 110. (7) The
`distal end of each conductor cable can be Welded to the
`ring-shaped electrode contact. (8) Polyurethane mono?la
`ment may be placed inside the void space as shoWn in FIG.
`6A, and inside any empty conductor lumens 116. (9) A heat
`shrink tube or Wrap, preferably, made from PTFE (Te?on) or
`polyester, can be placed over the distal end of the lead assem
`bly and over the electrode array; this distal end can be placed
`into a high temperature block, e.g., betWeen about 140-250
`degrees Celsius for a period of about 30 to 120 seconds. (10)
`The distal assembly can be removed from the heat and the
`shrink tube or Wrap can be removed. (10) Optionally, the
`distal tip of the lead can be formed using an RF Welder.
`Post processing of the lead is not alWays required. For
`example, grinding of the distal or proximal ends of the leads
`is not necessary With this method of manufacturing, although
`optionally, a centerless grinding process may be used, if
`desired.
`The method of making the distal and proximal part of the
`lead, in accordance With the present invention, eliminates
`most, if not all tooling, including eliminating the use of
`molds.
`The method of making a lead and the resulting multi
`contact lead, in accordance With the invention, provides
`advantages over conventional leads and methods of making a
`lead. A prior method of making the distal portion of the lead
`uses epoxy to ?ll the voids betWeen the spacer 61 and the
`contacts 17. This has certain disadvantages. For instance, use
`of an epoxy requires a curing step, e.g., of up to eight hours,
`adding to the total time required to build a lead. With use of
`epoxy, there may also be some variation in stiffness of the
`?nal lead assembly post-cure because the epoxy is generally
`a different material than the insulative body or spacers and
`because curing may occur unevenly. The use of like materials,
`e.g., polyurethane lead body, polyurethane spacers and poly
`urethane mono?lament can yield a better bond betWeen these
`parts.
`Although the lead and method of making the lead are
`described in the context of a spinal cord stimulation lead, it
`Will be understood by those skilled in the art that the same
`lead, albeit With appropriate dimensions for a particular appli
`
`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`8
`cation, and the method of making the lead may be used to
`make a multi-contact lead suitable for use in other applica
`tions, such as deep brain stimulation, cardiac stimulation and
`peripheral nerve stimulation.
`While the invention herein disclosed has been described by
`means of speci?c embodiments and applications thereof,
`numerous modi?cations and variations could be made thereto
`by those skilled in the art Without departing from the scope of
`the invention set forth in the claims.
`What is claimed is:
`1. A method of manufacturing a stimulation lead having a
`proximal end and a distal end, comprising:
`providing a plurality of conductive contacts located at an
`end of a lead body of the stimulation lead;
`disposing a plurality of conductor Wires in a plurality of
`conductor lumens formed in the lead body;
`connecting at least one of the plurality of conductor Wires
`to each of the conductive contacts;
`placing spacers betWeen pairs of adjacent conductive con
`tacts, Wherein portions of the conductor lumens are
`located beneath the plurality of conductive contacts and
`the spacers;
`inserting mono?lament into at least one portion of at least
`one of the conductor lumens of the lead body that is not
`occupied by the conductor Wires; and
`re?oWing at least one of the spacers or mono?lament into at
`least one portion of at least one of the conductor lumens
`not occupied by the conductive Wires by heating the
`spacers and mono?lament to a temperature to cause
`thermal ?oW or melting of at least one of the spacers or
`mono?lament.
`2. The method of claim 1, Wherein either the spacers or
`mono?lament is polyurethane.
`3. The method of claim 2, Wherein the mono?lament is a
`thermoplastic material.
`4. The method of claim 3, Wherein the heat applied is
`betWeen about 140 to 250 degrees Celsius.
`5. The method of claim 4, Wherein the heat is applied for
`betWeen about 15 to 120 seconds.
`6. The method of claim 1, Wherein the spacers are oversiZed
`in diameter, relative to a predetermined ?nal diameter of the
`lead.
`7. The method of claim 1, Wherein conductive contacts are
`in the form of rings.
`8. The method of claim 1, Wherein the conductive contacts
`are electrode contacts on the lead.
`9. The method of claim 1, Wherein the conductive contacts
`are connector contacts on the proximal end of the lead.
`10. The method of claim 1, Wherein the step of connecting
`a conductor Wire to each of the electrode contacts is accom
`plished by Welding each conductor Wire to each respective
`contact.
`11. The method of claim 1, Wherein the mono?lament is a
`different material than the spacers.
`12. The method of claim 1, Wherein the mono?lament is the
`same material as the spacers.
`13. The method of claim 5, Wherein the heat applied is
`about 160 degrees Celsius for about 40 seconds.
`14. The method of claim 1, Wherein the plurality of elec
`trically conductive contacts are located on the proximal end
`of the stimulation lead.
`15. The method of claim 1, Wherein the plurality of elec
`trically conductive contacts