Improved surgical electrodes and leads for use with implantable pulse generators and methods of use

Abstract

An implantable pulse generator is provided having a non-metallic shell adjacent to a header, the header adjacent an optical window in the shell, the header aligning a series of surgical or percutaneous leads with the optical window, the leads incorporating optical fibers for distributing stimulation signals, electrodes, and contacts, and a series of optical devices provided behind the optical window for transmitting or receiving light from the fibers. A signal processor is provided for interpreting the signals from the optical fibers and mitigating continuous electromagnetic inductive charging.

Description

[Technical Field]

[0001] The present invention relates to an improved implantable pulse generator (IPG) and header combination for use with optical reflectometry in spinal cord stimulation (SCS). [Background technology]

[0002] Chronic pain can arise from a variety of conditions, particularly from nerve injury, as in the case of neuropathic pain, or from chronic stimulation of mechanical nociceptors, as in spinal pain. Functional ability can be severely affected by pain that is often refractory to pharmacological and surgical treatments. In such cases, spinal cord stimulation (SCS) is an effective treatment for pain by modulating the physiological transmission of pain signals from the periphery to the brain. This can be achieved by applying electrical stimulation to the spinal cord via an electrode array implanted adjacent to the spinal canal.

[0003] Electrode leads for spinal cord stimulator (SCS) systems can be classified as either "percutaneous leads" or "surgical leads." Percutaneous lead arrays contain multiple cylindrical electrode contacts arranged collinearly along a thin cylindrical cable that is introduced into the body via an injection needle. In contrast, surgical leads generally consist of an array of electrode contacts protruding to one side from a thin lead body composed of a flexible panel that is placed directly into the dorsal epidural space via a surgical laminotomy.

[0004] In Figure 1, the spinal column 1 includes multiple vertebrae, grouped into four sections or types: lumbar 2, thoracic 3, cervical 4, and sacral 5. The cervical vertebrae 4 include the first cervical vertebra (C1) through the seventh cervical vertebra (C7). Immediately below the seventh cervical vertebra are the first of twelve thoracic vertebrae 3, including the first thoracic vertebra (T1) through the twelfth thoracic vertebra (T12). Immediately below the twelfth lumbar vertebra 3 are five lumbar vertebrae 2, including the first lumbar vertebra (L1) through the fifth lumbar vertebra (L5), with the fifth lumbar vertebra attached to the sacral vertebrae (S1 through S5), which naturally fuse together in adults.

[0005] Figure 2 shows a representative thoracic vertebra 10, which shares several notable features with the lumbar vertebrae 2 and cervical vertebrae 4. The thick, oval portion of bone that forms the anterior surface of the vertebra 10 is the vertebral body 12. The vertebral body 12 is attached to the bony vertebral arch 13, through which the spinal nerves 11 pass. The vertebral arch 13, which forms the posterior portion of the vertebra 10, is composed of two pedicles 14, which are short, sturdy processes extending from the sides of the vertebral body 12 and the bilateral laminae 15. Broad plates projecting from the pedicles 14 join in a triangular formation to form a hollow archway, the spinal canal 16. Spinous processes 17 project from the junctions of the bilateral laminae 15. Transverse processes 18 project from the junctions of the pedicles 14 and the bilateral laminae 15. The vertebral arch structures protect the spinal cord 20 and spinal nerves 11 that pass through the spinal canal.

[0006] Surrounding the spinal cord 20 is the dura mater 21, which contains cerebrospinal fluid (CSF) 22. The epidural space 24 is the space within the spinal canal outside the dura mater.

[0007] 1, 2 and 3, prior art electrode array placement for spinal cord stimulation is shown. An electrode array 30 is placed in the epidural space 24 between the dura mater 21 and the wall of the spinal canal 16 toward the dorsal aspect of the spinal canal nearest the bilateral lamina 15 and spinous processes 17.

[0008] 4 shows a prior art surgical electrode array 30 including electrode contacts 35 sealed in a resilient housing 36. The electrode array 30 has electrode leads 31 connected to an electrical pulse generator 32 and a controller 33. Each electrode contact has a separate conductor within the electrode lead 31 so that the current to each contact can be controlled independently.

[0009] Spinal cord stimulators often include an implantable pulse generator (IPG) 32 that monitors and delivers the electrical stimulation to the spine via the electrode array 31. The IPG is typically implanted subcutaneously near the upper buttocks or flank and is contained in a titanium can that draws power from a battery. The electrode array is connected to the IPG using subcutaneous leads.

[0010] The subcutaneous leads connect to electrode contacts on the header of the IPG, and are typically secured to the IPG with anchor screws.

[0011] The IPG delivers pulses of electrical current to the electrode array, which passes through the electrodes to target neurons in the ascending tract of the spinal cord. The resulting electric field disrupts pain perception. Controlling the amplitude of the stimulating electric field is paramount to the success of spinal cord stimulation. Insufficient current will fail to depolarize the target neurons, rendering the treatment ineffective. Conversely, excessive current will depolarize the target neurons but stimulate additional cell populations, resulting in the perception of noxious stimulation.

[0012] Establishing a consistent, therapeutic, and non-toxic level of stimulation is predicated on establishing an ideal current density within the target neurons of the spinal cord. Essentially, this should be a simple matter of establishing an optimal electrode current, taking into account the local bulk conductivity of the surrounding tissue. In reality, however, because the spinal cord is suspended in cerebrospinal fluid within the spinal canal, spinal cord movement alters the optimal electrode current as a function of patient position and activity. Significant changes have been shown to occur in the distance between the epidural electrode array and the target spinal neurons. Therefore, optimal stimulation requires dynamic adjustment of the electrode stimulation current as a function of the distance between the electrode array and the spinal cord.

[0013] Dynamic modulation of spinal cord stimulator electrode current as a function of the distance between the electrode array and the spinal cord therefore has several advantages: excessive stimulation current can be avoided, thereby reducing the potential for harmful stimulation and potentially reducing device power consumption; insufficient stimulation current can be avoided, thereby eliminating periods of reduced therapeutic efficacy.

[0014] Dynamic modulation of electrode current can be controlled through the use of optical reflectance measurements to determine the thickness of the dorsal cerebrospinal fluid (dCSF) column between the spinal cord and the electrode array. Optical signals are transmitted to the surrounding tissue and collected by a sensor, and the approximate distance between the electrode and the spinal cord is calculated. Stimulation amplitude is modified accordingly to provide the optimal current for pain relief. An example of this technique is shown in U.S. Patent No. 10,035,019 to Wolf II, incorporated herein by reference.

[0015] One challenge for subcutaneous IPG implants is the long-term survival of the IPG in the harsh in vivo environment. Intrusion of bodily fluids can lead to functional and mechanical degradation. Proteins commonly found in blood and interstitial fluid are known to bind to metal ions and cause corrosion. Some materials can trigger an immune response and alter the local pH balance at the implantation site. Specialized polymers and epoxy resins can circumvent some of these issues but often exhibit unacceptably high levels of cytotoxicity. As a result, it is essential that the internal IPG components be maintained in a sealed environment and that the external IPG components be biocompatible.

[0016] Similarly, another challenge with subcutaneous IPG implants is that the surrounding tissue tends to deteriorate around the IPG due to the increased pressure that the edges of the IPG exert on the tissue. Erosion of the device through the skin can occur, usually at the corners of the device where pressure is concentrated, necessitating revision surgery to replace the device.

[0017] Another challenge to implementing optical reflectometry for adaptive spinal cord stimulation is that leads imprecisely coupled to the IPG header are susceptible to movement that disrupts the stability of the optical signal. An unstable optical signal results in an undesirable signal-to-noise ratio that leads to errors in the delivered current and inaccurate stimulation.

[0018] Yet another challenge with subcutaneous IPG implants is extended recharge times. IPGs containing rechargeable batteries must be periodically recharged. Electromagnetic induction has evolved as the most widely used technology for recharging IPG batteries. However, during recharge, eddy currents are generated in the IPG's casing, causing a temperature rise. To maintain acceptable temperatures, the charge duty cycle is typically shorter than ideal, thereby extending the time required for recharging.

[0019] The prior art has attempted to address these challenges in several ways.

[0020] For example, U.S. Patent No. 6,011,993 to Tziviskos et al. describes a method for producing a strong ceramic case capable of housing electronic devices with a good hermetic seal for implantation in the body, but Tziviskos does not describe how to effectively connect or secure leads or optical fibers.

[0021] As another example, U.S. Patent No. 6,324,428 to Weinberg et al. describes a medical implant that includes internal electronics in a preferred configuration that minimizes the implant's volume and facilitates implantation, although Weinberg does not describe design features that reduce erosion of the device, nor does he describe methods for coupling electrical leads or optical fibers to the implant.

[0022] Similarly, U.S. Patent No. 7,742,817 to Malinowski et al. describes an IPG with connectors for electrical leads and an epoxy coating for biocompatibility, although Malinowski does not disclose the use of optics in the design to achieve the appropriate pulse intensity.

[0023] Deficiencies exist in the prior art related to the accuracy of lead connections when using optical reflectometry for spinal cord stimulation. Thus, there is a need in the art for improved IPG cases, connectors, leads, and electrodes that provide a stable optical signal while optimizing the longevity of the IPG. The prior art documents relevant to the invention of this application are as follows (including documents cited in the international phase after the international filing date and documents cited when the application entered the national phase in other countries). (Prior art document) (Patent document) (Patent Document 1) U.S. Patent No. 4,541,440 (Patent Document 2) U.S. Patent No. 4,715,700 (Patent Document 3) U.S. Patent No. 6,011,993 (Patent Document 4) U.S. Patent No. 6,181,865 (Patent Document 5) U.S. Patent No. 6,190,333 (Patent Document 6) U.S. Patent No. 6,324,428 (Patent Document 7) U.S. Patent No. 6,777,666 (Patent Document 8) U.S. Patent No. 7,447,533 (Patent Document 9) U.S. Patent No. 7,742,817 (Patent Document 10) U.S. Patent No. 7,835,803 (Patent Document 11) U.S. Patent No. 8,646,172 (Patent Document 12) U.S. Patent No. 9,550,063 (Patent Document 13) U.S. Patent No. 10,035,019 (Patent Document 14) US Patent Application Publication No. 2004 / 0175080 (Patent Document 15) US Patent Application Publication No. 2005 / 0069272 (Patent Document 16) U.S. Patent Application Publication No. 2007 / 0100398 (Patent Document 17) US Patent Application Publication No. 2007 / 0179538 (Patent Document 18) U.S. Patent Application Publication No. 2008 / 0077190 (Patent Document 19) US Patent Application Publication No. 2008 / 0097554 (Patent Document 20) US Patent Application Publication No. 2008 / 0183257 (Patent Document 21) US Patent Application Publication No. 2008 / 0195187 (Patent Document 22) U.S. Patent Application Publication No. 2009 / 0125090 (Patent Document 23) U.S. Patent Application Publication No. 2009 / 0192580 (Patent Document 24) U.S. Patent Application Publication No. 2009 / 0270953 (Patent Document 25) U.S. Patent Application Publication No. 2010 / 0029127 (Patent Document 26) U.S. Patent Application Publication No. 2010 / 0035453 (Patent Document 27) U.S. Patent Application Publication No. 2010 / 0253949 (Patent Document 28) U.S. Patent Application Publication No. 2010 / 0256693 (Patent Document 29) U.S. Patent Application Publication No. 2011 / 0046700 (Patent Document 30) U.S. Patent Application Publication No. 2011 / 0101914 (Patent Document 31) U.S. Patent Application Publication No. 2011 / 0176770 (Patent Document 32) U.S. Patent Application Publication No. 2011 / 0190608 (Patent Document 33) U.S. Patent Application Publication No. 2011 / 0191275 (Patent Document 34) U.S. Patent Application Publication No. 2013 / 0030352 (Patent Document 35) U.S. Patent Application Publication No. 2013 / 0317572 (Patent Document 36) U.S. Patent Application Publication No. 2014 / 0148753 (Patent Document 37) U.S. Patent Application Publication No. 2014 / 0296952 (Patent Document 38) U.S. Patent Application Publication No. 2014 / 0330341 (Patent Document 39) U.S. Patent Application Publication No. 2014 / 0340741 (Patent Document 40) U.S. Patent Application Publication No. 2015 / 0093082 (Patent Document 41) U.S. Patent Application Publication No. 2016 / 0250471 (Patent Document 42) U.S. Patent Application Publication No. 2016 / 0341899 (Patent Document 43) U.S. Patent Application Publication No. 2017 / 0031111 (Patent Document 44) U.S. Patent Application Publication No. 2017 / 0252564 (Patent Document 45) U.S. Patent Application Publication No. 2018 / 0110971 (Patent Document 46) U.S. Patent Application Publication No. 2018 / 0147077 (Patent Document 47) U.S. Patent Application Publication No. 2018 / 0154152 (Patent Document 48) U.S. Patent Application Publication No. 2018 / 0326219 (Patent Document 49) U.S. Patent Application Publication No. 2018 / 0344130 (Patent Document 50) U.S. Patent Application Publication No. 2019 / 0060656 (Patent Document 51) U.S. Patent Application Publication No. 2021 / 0281003 [Brief explanation of the drawings]

[0024] In the detailed description of the preferred embodiments presented below, reference is made to the accompanying drawings. [Figure 1] FIG. 1 is a lateral view of the human spine showing the approximate location of an electrode array for spinal cord stimulation. [Figure 2] Figure 2 shows an axial view of the thoracic spine showing the location of the spinal cord and electrode array for spinal cord stimulation. [Figure 3]FIG. 3 shows a sagittal section of the human spine showing the approximate location of an electrode array for spinal cord stimulation. [Figure 4] FIG. 4 shows a prior art surgical electrode array and lead connector for spinal cord stimulation. [Figure 5] FIG. 5 shows a schematic diagram of a preferred embodiment IPG charging and communication system. [Figure 6A] FIG. 6A is an isometric view of a recommended IPG device. [Figure 6B] FIG. 6B is a cross-sectional top view of a preferred IPG shape showing a hyperelliptic curve. [Figure 6C] FIG. 6C is a cross-sectional front view of a preferred IPG shape showing a hyperelliptical curve. [Figure 6D] FIG. 6D is a cross-sectional side view of a preferred IPG shape showing a hyperelliptical curve. [Figure 6E] FIG. 6E is an isometric view of a preferred IPG shape showing a hyperelliptic curve. [Figure 6F] FIG. 6F is an isometric view of a recommended IPG device. [Figure 7A] FIG. 7A is a side view of the header of a preferred IPG device. [Figure 7B] FIG. 7B is a cross-sectional top view of the header of a preferred IPG device. [Figure 7C] FIG. 7C is a detailed view of a recommended header for an improved IPG device. [Figure 7D] FIG. 7D is a top view of the priority header bay of the improved IPG device. [Figure 7E] FIG. 7E is a rear view of the header of the improved IPG device. [Figure 8] FIG. 8 is a cross-sectional view of a preferred IPG body. [Figure 9A] FIG. 9A is a plan view of the optical window of the improved IPG device. [Figure 9B] FIG. 9B is a cross-sectional side view of an optical window for an improved IPG device. [Figure 10A] FIG. 10A is a plan view of the optical window of the improved IPG device. [Figure 10B] FIG. 10B is a cross-sectional side view of an optical window for an improved IPG device. [Figure 11A] FIG. 11A is a plan view of the optical window of the improved IPG device. [Figure 11B] FIG. 11B is a cross-sectional side view of an optical window for an improved IPG device. [Figure 11C] FIG. 11C is an isometric view of the optical window of the improved IPG device. [Figure 11D] FIG. 11D is an isometric view of the optical window of the improved IPG device. [Figure 12A] FIG. 12A is a front view of a daughter board suitable for an improved IPG device. [Figure 12B] FIG. 12B is a rear view of a daughter board suitable for the improved IPG device. [Figure 12C] FIG. 12C is an isometric view of a daughter board suitable for the improved IPG device. [Figure 12D] FIG. 12D is a schematic diagram of the optical signals of the improved IPG device. [Figure 12E] FIG. 12E is a graphical representation of the advantages of the lead configuration. [Figure 12F] FIG. 12F is a method diagram for calculating the stimulus. [Figure 12G] FIG. 12G is a front view of the daughter board of the improved IPG device. [Figure 12H] FIG. 12H is a rear view of the daughter board of the improved IPG device. [Figure 12I] FIG. 12I is an isometric view of the daughter board of the improved IPG device. [Figure 12J] FIG. 12J is a schematic diagram of the optical signals of the improved IPG device. [Figure 13A] FIG. 13A is a side view of a preferred embodiment of a subcutaneous lead. [Figure 13B] FIG. 13B is a cross-sectional view of a preferred embodiment of a subcutaneous lead. [Figure 13C]FIG. 13C is a cross-sectional view of an alternative embodiment of a subcutaneous lead. [Figure 13D] FIG. 13D is an exploded side view of the optical fiber and ferrule configuration. [Figure 13E] FIG. 13E is a side view of a preferred embodiment of the optical fiber and ferrule assembly. [Figure 13F] FIG. 13F is an exploded side view of the optical fiber and collet components. [Figure 13G] FIG. 13G is a side view of a preferred embodiment of the optical fiber and collet assembly. [Figure 13H] FIG. 13H is an exploded side view of the lead assembly. [Figure 13I] FIG. 13I is a top view of the fiber optic threading component. [Figure 13J] FIG. 13J is a top view of the fiber optic threading component. [Figure 13K] FIG. 13K is an exploded perspective view of the fiber optic threading assembly. [Figure 14A] FIG. 14A is a plan view of a preferred surgical lead. [Figure 14B] FIG. 14B is a cross-sectional view of a preferred surgical lead. [Figure 14C] FIG. 14C is a cross-sectional view of a preferred surgical lead. [Figure 15A] FIG. 15A is a plan view of a preferred surgical lead. [Figure 15B] FIG. 15B is a cross-sectional view of a preferred surgical lead. [Figure 16A] FIG. 16A is a plan view of a surgical lead. [Figure 16B] FIG. 16B is a cross-sectional view of a surgical lead. [Figure 16C] FIG. 16C is an isometric view of a parabolic reflector for a surgical lead. [Figure 17A] FIG. 17A is a plan view of a surgical lead. [Figure 17B] FIG. 17B is a cross-sectional view of a surgical lead. [Figure 18]FIG. 18 is a flow chart of the steps of a preferred method for surgical lead placement. [Figure 19] FIG. 19 is a flow chart of the steps of a preferred method for placing percutaneous leads. [Figure 20] FIG. 20 is a method flow chart of the steps of a preferred method for securing an optical fiber in the stylet pathway of a lead. DETAILED DESCRIPTION OF THE INVENTION

[0025] In the following description, like parts are designated throughout the specification and figures are designated with the same numerals. The figures are not necessarily drawn to scale and may be shown in exaggerated or generalized form for clarity and conciseness.

[0026] Referring now to FIG. 5, an IPG charging and communication system 500 includes an IPG device 510 implanted subcutaneously below the skin surface 530 .

[0027] The IPG device 510 has an external non-metallic case 507 that facilitates charging and transmission of communication signals, along with an external system manager 516, as further described.

[0028] The IPG device 510 further includes a main processor 505 operably connected to the signal processor 509. The main processor 505 is further operably connected to a secondary coil 511 and an RF antenna 532, as will be described.

[0029] The signal processor 509 is operatively connected to the optoelectronic device 503 as will be further described.

[0030] Optoelectronic devices 503 are positioned to transmit and receive light to and from leads 512 of surgical leads 514, respectively, as will be further described.

[0031] Main processor 505 is further operatively connected to battery 533, secondary coil 511, and RF antenna 532. During use, main processor 505 relieves charge on battery 533 from current induced in secondary coil 511 by primary coil 518, as further described. Main processor 505 also receives signals from RF antenna 532 for use in communicating data regarding the operation of the IPG device, as further described.

[0032] The system further includes an external system manager 516. The external system manager 516 includes an external processor 520 operatively connected to a primary coil 518 and an RF antenna 534.

[0033] During use, external processor 520 contains a set of instructions that control the charging signal sent to primary coil 518. During use, primary coil 518 is physically located near secondary coil 511 and activated. Activation of the primary coil induces a current in the secondary coil that is sent by the main processor to the battery to charge the battery. Because no eddy currents occur in the non-metallic case, activation of the primary coil and inductive charging of the battery can continue. The continuous charging duty cycle of the IPG is significantly improved over prior art, reducing IPG charging times.

[0034] RF antenna 534 is used to send and receive signals to RF antenna 532 to receive information and control the operation of IPG device 510, as will be further described.

[0035] 6A, an IPG device 501 includes an IPG body 506 and a header 502. Leads 504 are removably secured to the header, as will be further described.

[0036] Next, a preferred shape of the IPG device 501 will be described with reference to Figures 6B, 6C, 6D, and 6E. In general, the preferred shape of the IPG case is defined by the equations of two unique superellipses, one for each side and top view. The case is symmetric about each major axis. The outer shape of the IPG case is important because a near-Gaussian distribution of curvature across the surface significantly reduces the risk of the case eroding through the skin after implantation of the IPG device, thereby improving the survival rate of surgical implants. The equation of the preferred superellipses defining the case shape is preferably a Lamé curve equation.

[0037] The three-dimensional shape of the device is a volume of revolution with major axes x, y, and z. The volume of the revolution is symmetrical about each major axis. Referring to Figure 6C, from the front, in the xy plane, the revolution is preferably a circle defined by the following equation:

[0038]

number

[0039] where: a = width along the x-axis b = height along the y-axis r=radius Typical values ​​for a and b are about 50 mm. Typical values ​​for r are about 25 mm.

[0040] Referring to FIG. 6D, when viewed from the side, in the yz plane, the solid of revolution is preferably super, defined as:

[0041]

number

[0042] where: b = height along the y-axis c = depth along the z axis n is between about 1.5 and about 5, and is preferably about 2. A typical value for b is about 50 mm. A typical value for c is about 12 mm.

[0043] In one preferred embodiment, the hyperellipsoid in the yz plane is rotated about the z axis to obtain the volume of the body of revolution.

[0044] Referring to FIG. 6B, from above, in the xz plane, the volume of the solid of revolution is preferably a super-ellipse defined by the following equation:

[0045]

number

[0046] where: a = width along the x-axis c = depth along the z axis A typical value for a is about 50 mm. A typical value for c is about 12 mm.

[0047] Referring now to FIG. 6F, an exploded view of the improved IPG device 600 will be described.

[0048] The IPG device 600 is comprised of a header 602 and an IPG body 606. The IPG body 606 is further comprised of an IPG casing 622, an optical window 618, and an electrical feedthrough plate 616. The IPG casing 622 is formed by two opposing shell halves, 622a and 622b, sealed at a joint 620. In a preferred embodiment, the IPG casing 602 is a ceramic material such as alumina, sapphire, or zirconia. In another embodiment, the IPG casing can be formed from a molded amorphous glass such as Pyrex®. In an alternative embodiment, the IPG casing is comprised of titanium or an alloy. In a preferred embodiment, ceramic brazing with induction welding is applied to the joint of the casing halves. Other processes can be used to join the halves.

[0049] The header is secured to the header bay 619 by a suitable medical grade permanent adhesive, as will be further described.

[0050] Optical window 618 is preferably a crystalline insert in the wall of the header bay sealed within the IPG casing, as will be further described. Alternatively, in embodiments in which the IPG casing is formed of an optically transparent material, optical window 618 can take the form of a pair of polished surfaces integrally formed in the header bay wall of the IPG casing adjacent the header body.

[0051] Lead wires 604 are removably coupled to header 602 and secured in place using anchor screws 614 or 615 as will be further described.

[0052] Referring now to FIG. 7A, header 700 is comprised of header body 701. The header body is preferably formed of a cast, rigid, non-metallic material strong enough to support the radial force from the anchor screws, such as methyl PMMA or glass or graphite fiber reinforced polyester. The header body includes a plurality of generally latitudinal and parallel lead channels, such as lead channel 702. In a preferred embodiment, the header body includes four lead channels. Alternatively, there may be two lead channels. Each lead channel, such as lead channel 702, is generally cylindrical and includes a lead channel axis, such as axis 719, which defines the optical axis of the lead, as will be further described.

[0053] Each lead channel includes eight annular connector bays, such as connector bay 703, formed in series within the channel. The connector bays 703 are equally spaced along the channel axis of each lead channel. Each connector bay houses a canted coil connector spring, such as canted coil spring 704. Each canted coil connector spring is a helical metal coil that forms an annulus and is spring-loaded to exert an inwardly directed radial bias on a metal lead connector, as described further below. Preferably, the canted coil springs are platinum alloys to ensure fail-safe electrical and mechanical contact with the lead contacts. In a preferred embodiment, the canted coil springs are Bal Conn® canted coil springs for neuromodulation therapy, available from Bal Seal Engineering of Foothill Ranch, California. Each canted coil spring is connected to one connector pin, such as connector pin 706, at the base of the header.

[0054] Header body 701 is adjacent to the IPG casing and includes a set of horizontal threaded holes that extend from the exterior of the header body to the lead channels and are perpendicular to the lead channels, such as threaded hole 732. An anchor screw, such as anchor screw 708, is disposed in each threaded hole.

[0055] In a preferred embodiment, the threaded holes are drilled or cast directly into the header body, or are threaded into the IPG case. The IPG casing is molded into the header. This configuration is important because it eliminates the need for separate anchor blocks in the header, saving space by incorporating these components into the IPG casing. Additionally, locating the anchor screws nearest the proximal end of the lead channel provides a secure mechanical connection of the lead nearest the optical component, promoting a stable optical signal.

[0056] Optionally, the header body can further include an integrally formed anchor block 799. In this embodiment, the threaded hole and anchor screw are present in the anchor block adjacent the optical window. The anchor block is preferably a medically inert metal, such as titanium, that is molded into the header body.

[0057] 7B, threaded hole 732 receives anchor screw 708. Directly opposite threaded hole 732 is threaded hole 707. Threaded hole 707 receives anchor screw 705.

[0058] 7C, frusto-conical centering surface 724 is adjacent to and coaxial with lead channel 702. When the lead is inserted into the lead channel, frusto-conical centering surface 724 centers the lead on the optical axis of the lead channel. Adjacent to the frusto-conical centering surface is anchoring chamber 728. The anchoring chamber is bounded by cylindrical alignment surface 726 and is coaxial with the frusto-conical centering surface. The anchoring chamber is also bounded by stop surface 730. Stop surface 730 is an annular ring at the proximal end of the anchoring chamber. The stop surface is coaxial with the anchoring chamber. During use, stop surface 730 abuts the proximal end of the lead body and prevents insertion beyond a desired point in lead channel 702 during assembly. Each of these surfaces is important for precise alignment of the leads and the optical fibers to facilitate efficient and accurate transfer of optical signals.

[0059] Anchor screws 708 engage the lead wire anchor rings in the anchor ring chambers when the IPG is assembled. If the header body has threaded holes, install the anchor screws with a torque-limiting driver to avoid applying undue stress to the header. If the header body includes the anchor block, the anchor block allows the anchor screws to apply sufficient axial force to the anchor rings to hold them securely in place without damaging the header body.

[0060] The lead channel further comprises a ferrule chamber 727 bounded by an alignment cylinder 712. The ferrule chamber is coaxial with the lead channel.

[0061] A ferrule centering surface 716 is adjacent to and coaxial with the alignment cylinder 712 and is designed to optically align the ferrule and the optical fiber with the optical axis of the lead channel. The alignment cylinder 712 forms a chamfer angle 8 with the ferrule centering surface 716. In a preferred embodiment, the chamfer angle 8 ranges from about 135° to about 150°, ±5°. The ferrule centering surface 716 centers and aligns the lead and the proximal end of the optical ferrule with the buffer gap 734, the optical window 718, and the composite optoelectronic device 740.

[0062] Cylindrical buffer surface 714 is adjacent to and coaxial with ferrule centering surface 716. Cylindrical buffer surface 714 forms a buffer gap 734 between the proximal end of the optical ferrule and optical window 718. The buffer gap prevents pressure on the optical window from fluid or tissue accumulation at the ferrule tip or from irregularities in the polished surface of the optical fiber at the ferrule tip.

[0063] Referring now to FIG. 7D, the electrically piercing plate 616 comprises a flat insulating body, preferably a ceramic material, and is secured to the plate by a suitable adhesive or ceramic. The header body is secured to the bottom of the header bay 619 by a miscible weld. The electrical feedthrough plate 616 is comprised of multiple receivers, such as receiver 746, which are connected to a main circuit board as will be further described. Connector pins 706 at the base of the header body interface with the receivers.

[0064] 7E, in a preferred embodiment, the header is comprised of four lead channels 702, 709, 713, and 717. Each lead channel includes a vertically oriented threaded hole 732, 707, 733, and 739 and an anchor screw 708, 705, 711, and 715, respectively.

[0065] In the prior art, there is typically an anchor ring engaged by a set screw to secure the lead contact within the header. The anchor ring is typically located distal to the contact, requiring a separate anchor block to engage the lead and set screw. One advantage of this embodiment is that the anchor ring can be located proximal to the lead contact, closest to the end of the lead. This location eliminates the need for a separate anchor block and reduces the size of the IPG casing if threaded holes 732, 707, 733, and 739 are integrated into the header body, as can be achieved by ceramic or glass injection molding. Furthermore, the location of the anchor ring closest to the proximal tip of the lead provides mechanical fixation of the lead closest to the optical component, promoting a stable optical signal.

[0066] Referring now to FIG. 8, the IPG body 800 is further comprised of an IPG casing 802, an optical window 806, an electrical feedthrough plate 804, a composite optoelectronic device 816, a connector card 812, a main circuit board 818, a battery 808, and a capacitor 810.

[0067] The electrical components are secured within the casing with suitable insulating plastic standoffs such as standoffs 820 and 821 .

[0068] Adjacent the header bay, an electrical feedthrough plate 804 is sealed to the IPG casing 802. The electrical feedthrough plate is mechanically secured to a connector card 812 and connected to a main circuit board 818 by a flexible ribbon cable 805.

[0069] An optical window 806 is sealed to the IPG casing at a position perpendicular to both the electrical feedthrough plate and the lead channel. In a preferred embodiment, the optical window 806 is constructed from synthetic sapphire, which provides optimal optical properties for transmitting visible red or infrared light between a composite optoelectronic device 816 and an optical transmission fiber, as will be further described.

[0070] A composite optoelectronic device 816 is positioned adjacent to the optical window and held in a parallel position with the optical window by the daughter board. The optoelectronic device 816 is also perpendicular to the optical axis of the lead channel. Daughter board 814 further comprises a processor 803, as will be further described. Daughter board 814 is held in place by the standoffs and connected to a main circuit board 818 by a ribbon cable 807, which provides power to the daughter board and communicates control signals as needed.

[0071] A main circuit board 818 is disposed within the IPG casing by the isolation and is operatively connected to the battery, the capacitor, the lead contacts, and the daughter board.

[0072] A main circuit board 818 receives data input from the daughter board and generates stimulation pulses of varying frequency, pulse width, and amplitude based on signals from the daughter board. The stimulation pulses are sent to the lead contacts for transmission to the electrodes. The daughter board generates control signals for the main circuit board by transmitting light pulses from the light emitters and receiving and interpreting signals from the photodetectors, as further described. The main circuit board is also operably connected to a secondary inductive coil 809 and an RF antenna 811.

[0073] The main circuit board includes a processor and a signal generator that allows signals to be communicated to an external receiving device via an RF antenna 811. In a preferred embodiment, the main circuit board and the RF antenna are used to communicate a warning signal from the daughter board when the emitter current reaches a maximum value, as will be further described.

[0074] A capacitor 810 is connected to battery 808 and stores energy from the battery to generate the stimulation pulses. In a preferred embodiment, battery 808 is a rechargeable lithium-ion battery. Battery 808 is inductively charged via a secondary inductive coil 809 positioned around the battery on one interior surface of the IPG casing. The main circuit board controls the recharging duty cycle.

[0075] 9A and 9B, in a preferred embodiment, the optical window 900 is a polished rectangular single crystal alumina (sapphire) or polycrystalline alumina ceramic. It is ceramic brazed to the header bay IPG case 901. Niobium is used as a metal-to-ceramic filler material. In a preferred embodiment, the alumina is 94% brazed to Fe-29Ni-10Co internally at approximately 1000°C. The optical window 900 is brazed to the IPG case 901 along a window braze joint 906 using a hermetic braze fillet 904. While the optical window 900 and IPG case 901 are shown coplanar in FIG. 9B, they may alternatively be stacked or overlapped.

[0076] 10A and 10B, in another embodiment, an optical window 1000 is overlaid on the outside of an IPG case 1001 adjacent to the header bay. In this embodiment, the IPG case 1001 includes four (4) waveguides 1008, which are holes in the header bay wall that allow red or infrared light to transmit through the optical window along the optical axis of each lead channel and into the interior of the IPG casing. The optical window 1000 is sealed to the IPG case along window joint 1006 using brazing, soldering, epoxy, or other suitable means.

[0077] 11A, 11B, 11C, and 11D, in another preferred embodiment, the pane 1104 comprises a flat sapphire rectangle approximately 1 mm thick. Four light guides 1106 are fused to the pane using ceramic welding. In another embodiment, the pane and the light guides are integrally formed from the same crystalline structure. Each light guide includes an internally reflective iris 1108. The iris is a cylindrical hole concentrically aligned with the optical axis of the lead channel. The pane 1104 is laser welded to the IPG casing 1101 along weld joints 1102.

[0078] When assembled, each of the optical waveguides passes through hole 1110 into the interior of the IPG casing. In a preferred embodiment, each optical waveguide is adjacent to an optoelectronic device on the daughter board that is secured to the IPG casing, as described above. In practice, the iris is important because it prevents light loss between the optical fiber in the lead and the optoelectronic device.

[0079] 12A, 12B, and 12C, the daughterboard 814 is preferably a double-sided PC board supporting optoelectronic devices 1204, 1205, 1206, and 1270, a connector 1210, and a processor 1208. The processor 1208 draws power from the battery and is provided with on-board memory containing instructions for its operation. The optoelectronic devices are arranged in quadrants adjacent to the proximal surface of the optical window. Each quadrant is separated by an optically opaque optical baffle 1212. In a preferred embodiment, the baffle is a "cross"-shaped PVC isolation approximately 1-2 mm high, coated on its outer surface with a reflective layer such as TiO2, and adhered to the daughterboard with a suitable adhesive. Each optoelectronic device is positioned perpendicular to and aligned with the optical axis of one lead channel to maximize either the transmission or reception of light from the optical fiber disposed in the lead channel. In a preferred embodiment, the optoelectronic devices 1204, 1205, 1206, and 1207 and the optical baffle 1212 are integrated into one or more application specific integrated circuits (ASICs).

[0080] A connector 1210 links a daughterboard 814 to the main circuit board of the IPG device. A processor 1208 is electrically connected to the optoelectronic device through the daughterboard as needed to communicate electrical signals to the processor.

[0081] In one embodiment, the optoelectronic device 1204 is a light emitter and the optoelectronic devices 1205, 1206, and 1205 are light detectors.

[0082] In another embodiment, optoelectronic devices 1204 and 1206 are light emitters and optoelectronic devices 1205 and 1206 are light detectors.

[0083] The emitter wavelength ranges from the visible red to the infrared, or approximately 620 to 1700 nanometers. The emitter can be either single-wavelength or multi-wavelength. For example, the emitter can be a high-speed, single-wavelength infrared light-emitting diode with a wavelength of 850 nm, such as part number VSMY1850 available from Vishay Intertechnology, Inc., Malvern, Pennsylvania. Alternatively, the emitter can be a multi-chip emitter capable of emitting wavelengths of 670 nm, 770 nm, 810 nm, 850 nm, and 950 nm, such as part number MTMD6788594SMT6 available from Marktech Optoelectronics, Inc., Latham, New York. Alternatively, the emitter and detector can be integrated into a single ASIC, such as the ADPD144RI available from Analog Devices, Inc., Norwood, Massachusetts.

[0084] Referring to Figure 12D, a preferred embodiment of the coupling configuration between the optical leads and the optical emitter in a surgical lead is described. Emitter 1292 is optically coupled to central fiber 1215 of surgical lead 1211. Detector 1290 is optically coupled to lead 1213 of surgical lead 1211. Detectors 1294 and 1296 are connected to leads 1217 and 1219, respectively.

[0085] Referring to Figure 12D, a preferred embodiment of the coupling configuration between the optical leads and the optical emitter in a surgical lead is described. Emitter 1292 is optically coupled to central fiber 1215 of surgical lead 1211. Detector 1290 is optically coupled to lead 1213 of surgical lead 1211. Detectors 1294 and 1296 are connected to leads 1217 and 1219, respectively.

[0086] Referring to FIG. 12E, a graph showing the light output from the side ignition fiber of a surgical lead and the input current to the corresponding emitter over time is illustrated.

[0087] Light output over time is shown by the curve labeled "a." It can be seen that the light output of fiber 1215 degrades over time due to microfractures of the fiber and other degradation of the optical components within the surgical lead. The degradation of the optical performance of fiber 1215 is monitored over time by processor 1208 by reading the voltage signal from detector 1296, which receives light from fiber 1215 reflected by the spinal cord. Processor 1208 is programmed to offset the degradation of the light output by increasing the current to emitter 1204 according to curve "b." As can be seen, increasing the current to emitter 1204 maintains the light output of fiber 1215 at a consistent level, as shown in the figure, indicated by curve "c."

[0088] 12F, an auto-adjusting emitter current program for adjusting the light output from the emitter fiber is described. In a preferred embodiment, the program is a series of instructions resident in the memory of processor 1208.

[0089] In step 1262, the program is started.

[0090] In step 1264, the processor sets the output current to emitter 1292. In a preferred embodiment, the emitter current is set to the minimum required to produce a readable signal at detectors 1290 and 1296.

[0091] In step 1266, the processor reads the voltage at detector 1294. In step 1268, the voltage level is stored in memory. In step 1270, processor 1208 sends a signal to main circuit board 818 to start a stimulation program. The main circuit board responds by sending the appropriate stimulation signal to the leads.

[0092] In step 1272, processor 1208 determines whether the self-timer has expired. If so, the program proceeds to step 1274. If not, the program returns to step 1270.

[0093] In step 1274 , processor 1208 reads the detector voltage at detector 1294 .

[0094] In step 1276, the processor compares the current detector voltage to the detector voltage stored in the memory. If the current detector voltage is less than the stored detector voltage, the process proceeds to step 1278. Otherwise, the program returns to step 1270.

[0095] In step 1278, processor 1208 increases the emitter current to emitter 1204. In a preferred embodiment, the emitter current is increased by 1 / 100 of the maximum allowed emitter current.

[0096] In step 128, the processor determines whether the emitter current is set to the maximum allowed. If so, the program moves to step 1282. If not, the program returns to step 1274.

[0097] In step 1282, the processor sends a signal to the main circuit board, which communicates it via the RF antenna to an external receiver, indicating that the maximum emitter current has been reached, after which the program returns to step 1270.

[0098] 12G, 12H, and 12I, alternative embodiments of daughterboard 814 will now be further described.

[0099] Daughterboard 1201 is a composite optoelectronic device comprised of optoelectronic devices 1250 and 1252, connector 1254, and signal processor 1209. The optoelectronic devices are positioned adjacent to and parallel to the optical window. In a preferred embodiment, each optoelectronic device is separated by an optically opaque light baffle 1251. In a preferred embodiment, baffle 1251 is a reflective or opaque rectangular PVC standoff bonded to the daughterboard, as previously described.

[0100] A connector 1254 links the daughter board 1201 to the main circuit board of the IPG device. A processor 1209 is electrically connected to the opto-electronic device through the daughter board as needed to communicate external signals to the signal processor. The daughter board communicates with the main circuit board through connector 1254.

[0101] Referring now to FIG. 12J, a preferred embodiment of a coupling configuration between the optical leads and the optical emitter in a surgical lead is described. Emitter 1293 is optically coupled to central fiber 1225 of signal lead 1221. Detector 1291 is optically coupled to lead 1223 of signal lead 1221. Emitter 1295 is optically coupled to central fiber 1227, which is connected to lead 1229. In this configuration, dual optical reflectance measurement channels facilitate stereoscopic detection of spinal cord position in the sagittal and coronal planes, as previously described in U.S. Patent Nos. 8,239,038, 8,543,213, 9,132,273, and 9,656,097 to Wolf II.

[0102] 13A-13G, a preferred embodiment of a percutaneous lead 1400 is described.

[0103] 13A and 13B, a preferred embodiment of the lead body 1402 comprises a generally hollow tube terminated in a transparent window 1409. In a preferred embodiment, the lead body is comprised of a flexible polymer such as Pellethane 55-D or a similar biocompatible polymer. The lead body is preferably a multi-lumen extrusion available from Zeus Industrial Products, Inc. of Orangeburg, South Carolina, USA.

[0104] A transparent window 1409 is a hollow cylinder fused to the end of the flexible lead body surrounding a diffusing cavity 1430. In a preferred embodiment, the window is a suitable optically transparent material such as thermoplastic polyurethane. The transparent window 1409 is terminated by a lid 1425. The lid 1425 includes an internal reflective surface 1403 that faces the diffusing cavity 1430. In a preferred embodiment, the internal reflective surface is a titanium dioxide coating.

[0105] A stylet channel 1405 extends from the transmission window to the proximal end of the lead body. The stylet channel serves two purposes: to house a guide stylet for use during intraoperative placement of the lead, and to house the housing and optical fiber post-operatively, as described further below. In a preferred embodiment, the stylet channel 1405 is lined with a polytetrafluoroethylene (PTFE) lining 1407 that extends the length of the lead body to the transmission window 1409. The very low surface friction provided by the carbon-fluorine bond in PTFE facilitates manual insertion of the stylet and optical fiber. To enhance light transmission, the lining does not extend into the diffusion cavity where the side-firing portion of the optical transmission fiber resides.

[0106] A metallic anchor ring 1410 is disposed at the proximal end of the lead body. The anchor ring is generally cylindrical and permanently attached to the exterior of the lead body proximal to the lead contacts. Eight cylindrical proximal metallic contacts 1408a, 1408b, 1408c, 1408d, 1408e, 1408f, 1408g, and 1408h are fixed to the exterior of the lead body at equal axial distances along the lead body and positioned to electrically contact the header coil spring.

[0107] Similarly, eight cylindrical distal metal electrodes 1406a, 1406b, 1406c, 1406d, 1406e, 1406f, 1406g, and 1406h are provided at the distal end of the lead body. Each of the distal lead contacts is permanently fixed to the outer surface of the lead. The distal lead contacts are equally spaced along the lead body proximal to the optical window.

[0108] The lead body further includes eight radially oriented lumens 1431a, 1431b, 1431c, 1431d, 1431e, 1431f, 1431g, and 1431h. Conductors 1420a, 1420b, 1420c, 1420d, 1420e, 1420f, 1420g, and 1420h are disposed within the lumens and extend from their respective proximal contacts to their respective distal electrodes. In a preferred embodiment, the conductors are constructed of MP35N or another similarly corrosion-resistant conductive material. Each of the conductors connects exactly one proximal contact to one of its paired distal electrodes.

[0109] Referring now to FIG. 13C, a cross-sectional view of an alternative embodiment of a lead body 1450 is illustrated.

[0110] Lead body 1450 has nine radially oriented lumens: 1449a, 1449b, 1449c, 1449d, 1449e, 1449f, 1449g, 1449h, and 1449i. Conductors 1451a, 1451b, 1451c, 1451d, 1451e, 1451f, 1451g, and 1451h and ground line 1451i are disposed in the lumens. Ground line 1451i extends from the proximal end of the lead body to the transmission window. Ground line 1451i is electrically connected to the anchor ring 1410. When the anchor screw engages anchor ring 1410, the ground lead is connected directly to the IPG ground through the anchor block or via a ground connection through the header. The ground line can be used to supplement the electrical shielding of the electrode array contacts to enhance MRI compatibility.

[0111] In another preferred embodiment, the lead body can incorporate a non-metallic shielding layer 1496 connected to a ground wire 1451i to further enhance MRI capabilities. In a preferred embodiment, the shielding layer is formed by carbon fiber infused into the surface of the lead body. In another preferred embodiment, a low friction layer 1493, such as PTFE, is included on the exterior of the lead body to aid in placement of the lead during surgery.

[0112] 13D and 13E, the fiber optic subassembly 1419 includes a ferrule 1412 and an optical fiber 1418.

[0113] The ferrule 1412 is typically a ceramic cylinder. The ferrule 1412 includes an integrally formed alignment tip 1413. The alignment tip 1413 is a chamfer formed on the ferrule at a chamfer angle of 8, preferably between approximately 135° and 150°. In a preferred embodiment, the chamfer angle 8 coincides with the chamfer angle 735 of the center face 716 so that when the ferrule is attached to the header, there is resilient compression of the ferrule by the polymer lead body. Once attached, the positive stop of the ferrule by the ferrule center face 716 prevents pressure from being applied to the fiber or the optical window 718 sealed by the ferrule. A bore 1415 is located in the center of the ferrule 1412 and extends the entire length of the ferrule. In a preferred embodiment, the diameter of the bore closely matches the diameter of the optical fiber. In a preferred embodiment, the ferrule 1412 is made of polished ceramic, preferably zirconia, or other MRI-compatible material.

[0114] A ferrule 1412 is disposed at the proximal end of the optical fiber 1418. The optical fiber 1418 includes a terminal reflector 1414 and a side-firing fiber portion 1416 at its distal end, and a polished optical tip 1411 at its proximal end. The optical fiber 1418 is preferably constructed of a polymethyl methacrylate core with a fluorocarbon coating approximately 250-400 micrometers in diameter. In a preferred embodiment, the fiber also includes a low-friction layer 1447, preferably made of PTFE. During use, the low-friction layer aids in the insertion of the fiber into the stylet lumen.

[0115] Optical fiber 1418 includes a reflector 1414 at its distal end. The reflector prevents axial emission from the fiber and improves radial dispersion of light. This improves optical signal strength and reduces power consumption. Ideally, the reflector consists of a layer of titanium dioxide coated onto the end of the fiber after it has been heat polished.

[0116] The side-ignition fiber portion 1416 is disposed within the diffusion cavity 1430, adjacent the lid portion 1425, and is typically approximately 5 mm in length. The side-ignition fiber portion 1416 is formed by modifying the coating of the optical fiber. The coating can be modified using femtosecond laser etching, mechanical abrasion, or an alternative method to achieve radial leakage of light.

[0117] A polished optical tip 1411 is disposed at the proximal end of the optical fiber. The polished optical tip 1411 is preferably a heat-polished surface perpendicular to the optical axis of the fiber. Optionally, a convex lens can be attached to the proximal end of the fiber to focus light into and out of the fiber, as further described.

[0118] 13E, a fiber optic subassembly 1419 is placed in the stylet channel 1405. The outer diameter of the ferrule 1412 is smaller than the outer diameter of the lead body 1402, but larger than the diameter of the stylet channel 1405, so that the lead body acts as a stop for the ferrule.

[0119] In one embodiment, a fiber optic subassembly 1419 is placed in the stylet channel after surgical placement of the lead body in vivo, as further described.

[0120] One such suitable medical grade adhesive is preferably an optically clear biocompatible epoxy sealant such as EPO-TEK® MED-353ND by Epoxy Technology, Inc. of Billerica, Massachusetts, USA, in which the polished optical tip 1411 is ground flush with the alignment tip 1413.

[0121] Referring now to FIG. 13F, an alternative embodiment of fiber optic subassembly 1419 will be described.

[0122] The lead body 1401 includes a stylet channel 1405 having an optical axis 1421. The lead body incorporates a proximal contact, a distal electrode, and a dielectric, as previously described. The stylet channel 1405 terminates in a full conical flare 1482. The full conical flare 1482 is coaxial with the optical axis 1421. The angle of inclination β of the full conical flare ranges from about 135 degrees to about 150 degrees.

[0123] In a preferred embodiment, the lead channel has a diameter approximately 15-20% larger than the optical fiber, allowing the fiber to travel within the channel. The optical fiber 1444 is preferably a plastic fiber, as previously described. The optical fiber 1444 includes an end reflector 1446 and a side firing portion 1445, as previously described.

[0124] Optical fiber 1444 is proximally terminated by a convex lens 1452. Convex lens 1452 is made of a polished ceramic material, such as sapphire, that is affixed to the optical fiber using a suitable optically clear adhesive. In another embodiment, the lens is integrally formed with the transmitting fiber. In another embodiment, the optical fiber is polished flat and does not incorporate a lens.

[0125] Collet 1457 includes a collet body 1453. Preferably, collet body 1453 is constructed from a ceramic material such as zirconia or another MRI-compatible material. Alignment tip 1454 is a chamfer integrally formed at the distal end of the collet body. Alignment tip 1454 forms a bevel angle γ of approximately 135 degrees. In a preferred embodiment, angle γ coincides with angle β of full conical flare 1482.

[0126] A lens shield 1469 is integrally formed with the proximal end of the collet body 1453. It is designed to act as a stop to prevent the optical fiber from colliding with the optical window of the IPG body. Lens shield 1469 further includes a frustoconical lens opening 1468 ducted to collet chamber 1456. The frustoconical lens opening is coaxial with the collet chamber and has an inclination angle δ of approximately 175 degrees with the collet chamber. The frustoconical lens opening 1468 serves to focus light toward the optical window.

[0127] 13G, the proximal end of the optical fiber is shown positioned within collet chamber 1456. Lens 1452 does not extend beyond lens shield 1469. The fiber is secured to the collet chamber with a suitable epoxy.

[0128] An optical fiber 1418 is positioned in the stylet channel 1405 of the lead body 1401. A frusto-conical flare 1482 helps guide the insertion of the optical fiber into the lead channel. The interface of the frusto-conical flare 1482 and alignment tip 1454 also serves to center the optical fiber 1444 and lens 1452 on axis 1421. The outer diameter of the collet 1457 is smaller than the outer diameter of the lead body 1401 but larger than the diameter of the stylet channel 1405, so that when the lead is inserted into the header, the lead body acts as a stop for the collet and the side-firing portion of the fiber is adjacent to the optical window.

[0129] Referring now to Figures 13H-13K, a preferred embodiment of the optical threading assembly 1460 is described. Inserting the optical fiber into the stylet channel of the lead can be difficult due to the small size of the fiber and the small diameter of the stylet channel. Similarly, during surgery, replacing a stylet within the stylet channel can be challenging. These difficulties are exacerbated by the need for speed, dexterity, and vision. Improper insertion of the optical fiber can lead to damage to the fiber, causing breakage or premature degradation of the fiber. Similarly, improper stylet insertion can put the lead body at risk. The optical fiber threading assembly solves these and other problems.

[0130] Optical threading assembly 1460 includes a guide body 1497. The guide body is cylindrical, approximately 1 cm in diameter, and constructed from thermoplastic plastic. The assembly is preferably formed using either injection molding or additive manufacturing; other manufacturing methods may suffice. Guide body 1497 is generally cylindrical and is constructed from two opposing half-cylinders 1461 and 1462.

[0131] The optical threading element 1460 includes a frustoconical lead centering surface 1463 at its distal end. The frustoconical lead centering surface 1463 is coaxial with the axis 1421. The frustoconical lead centering surface 1463 is adjacent to a cylindrical alignment surface 1467. The cylindrical alignment surface 1467 forms an alignment cavity 1498. The frustoconical lead centering surface 1463 forms an inclination angle τ of approximately 135° with the cylindrical alignment surface 1467. The alignment cavity has a diameter generally equal to the diameter of the lead body 1402. The alignment cavity terminates in a stop surface 1466. The stop surface 1466 is a generally annular ring formed perpendicular and coaxially with the axis 1421.

[0132] Adjacent to and ducted to the alignment cavity 1498 is a generally cylindrical fiber alignment duct 1499. The fiber alignment duct 1499 is coaxial with the axis 1421. The diameter of the fiber alignment duct is generally the same as the diameter of the stylet channel 1405 in the lead body 1402.

[0133] Fiber alignment duct 1499 is adjacent to and ducted to frustoconical fiber optic centering surface 1465. Frustoconical fiber optic centering surface 1465 forms an inclination angle η of approximately 135° with fiber alignment duct 1499. Frustoconical fiber optic centering surface 1465 is coaxial with axis 1421.

[0134] Half-cylinder 1461 includes alignment pegs 1474, 1470, and 1472. Half-cylinder 1462 includes alignment recesses 1475, 1471, and 1473. Alignment peg 1474 is diametrically opposed to alignment recess 1475. Alignment peg 1470 is diametrically opposed to alignment recess 1471. Alignment peg 1472 is diametrically opposed to alignment recess 1473. The diameters of alignment recesses 1475, 1471, and 1473, respectively, are such that alignment pegs 1474, 1470, and 1472 are secured by a press fit. As will be further described, the use of the alignment pegs and recesses allows the half-cylinder to be easily assembled, used, and disassembled after use.

[0135] In use, the optical threading assembly 1460 aligns the lead body 1402 and fiber optic subassembly 1419 along axis 1421. The lead body 1402 is aligned using the fulcrum conical lead centering surface 1463 and held in position within the alignment cavity 1498 by alignment surface 1467 and stop surface 1466. The fiber optic subassembly 1419 is aligned using the fulcrum conical centering surface 1465 and moved through the fiber alignment duct 1499 into the stylet channel of the lead body.

[0136] Similarly, a stylet can be placed in the stylet channel in place of the optical fiber.

[0137] The surgical lead may be configured with two or more multi-duct leads with integrated optical fibers, depending on the number of electrodes in the array and the desired number of optical reflectance measurement channels. The multi-duct leads may be organized into emitter and detector lead pairs. Typically, a surgical lead configured with two multi-duct leads incorporates one optical reflectance measurement channel, while a surgical lead configured with four multi-duct leads incorporates two optical reflectance measurement channels. A surgical lead with two multi-duct leads with integrated optical fibers can determine sagittal spinal position, while a surgical lead with four multi-duct leads with integrated optical fibers can determine sagittal and coronal spinal position.

[0138] Referring now to Figure 14A, a preferred embodiment of a surgical lead 1500 will be described.

[0139] The electrode array 1500 is comprised of an integrated flexible panel 1502. The panel 1502 is preferably a medical-grade inert polymeric material such as Pellethane 55-D. The flexible panel 1502 houses multi-duct leads 1506, 1510, 1514, and 1518. In a preferred embodiment, the multi-duct leads are encapsulated within the body of the flexible panel. Each of the multi-duct leads 1506, 1510, 1514, and 1518 includes a central lumen 1595, 1596, 1597, and 1598, respectively. Each central lumen contains a light-transmitting fiber 1541, 1543, 1545, and 1547, respectively. Each light-transmitting fiber terminates at the distal end of a side-firing fiber optic portion 1535, 1536, 1537, and 1538, respectively. The side-ignition fiber optic segments are constructed as previously described, with each side-ignition fiber optic segment positioned adjacent to a distally positioned optical window 1533, 1532, 1531, and 1530, respectively.

[0140] Panel 1502 further includes electrode arrays 1504, 1508, 1512, and 1516 disposed on adjacent multi-duct leads 1506, 1510, 1514, and 1518, respectively. In a preferred embodiment, electrode arrays 1504, 1508, 1512, and 1516 each include eight electrodes embedded in the panel and having exposed surfaces on the exterior of the panel. Each of multi-duct leads 1506, 1510, 1514, and 1518 incorporates eight electrical conductors extending the length of the panel and the multi-duct lead, as previously described. Each electrode is connected to exactly one lead contact via the conductors of the lead body. Electrode array 1504 is connected to lead contact 1507. Electrode array 1508 is connected to lead contact 1511. Electrode array 1512 is connected to lead contact 1515. The electrode array 1516 is connected to lead contacts 1519. In a preferred embodiment, the electrodes are constructed from a platinum-iridium alloy (nominal 90% / 10% to 80% / 20%).

[0141] Each of the multi-duct leads 1506, 1510, 1514, and 1518 terminates in a ferrule 1505, 1509, 1513, and 1517, respectively. In a preferred embodiment, the ferrules are coupled to fibers as previously described.

[0142] 14B and 14C, each of electrode arrays 1504, 1508, 1512, and 1516 is connected via electrical connections 1519, 1521, 1523, and 1525 to one of conductor bundles 1540, 1542, 1544, and 1546, respectively, which contain the individual conductors radially separated as described above. The side ignition fiber portions separate from the multi-duct lead and are spaced apart from the conductor bundles in manifolds 1580, 1581, 1582, and 1583, respectively.

[0143] Panel 1502 includes optical reflectors 1550, 1551, 1552, and 1553, adjacent side-fired optical fiber sections 1535, 1536, 1537, and 1538, respectively. The optical reflectors are preferably semi-cylindrical or parabolic and flexible. In a preferred embodiment, optical reflectors 1550, 1551, 1552, and 1553 are constructed from a non-conductive polymer material, such as Pellethan-55D, coated with a non-conductive reflective surface, such as titanium dioxide. This material operates at desired wavelengths from red to infrared and can be applied as a paint or film. The reflectors improve optical efficiency by redirecting radially generated light from the emitter fiber sections to the optical window or by reflecting incident light from the optical window to the detector fiber sections.

[0144] Panel 1502 further comprises a grid shield 1526. The grid shield 1526 is typically comprised of a flat flexible film that interlocks with the polymer material of the lead body. In a preferred embodiment, grid shield 1526 is coated with a reflective material such as titanium dioxide (TiO2) adjacent to the optical fibers. The grid shields are contained within the panel adjacent each of conductor bundles 1540, 1542, 1544, and 1546 and generally extend the length of the panel.

[0145] In one embodiment, the lattice shield is constructed of a conductive material, such as carbon nanofiber, and acts as a heat sink, drawing heat away from the electrode contact array and dissipating it toward the back. In another embodiment, as shown in FIG. 13C, each of the leads 1518, 1514, 1510, and 1506 includes a ground terminal. Ground wire 1451i connects the lattice shield 1526 to the anchor ring at the proximal end of the lead. The anchor ring is connected to an IPG ground terminal. This configuration provides optimal electrical shielding for MRI compatibility.

[0146] Referring now to FIG. 15A, a preferred embodiment of a surgical lead 1600 will be described.

[0147] The surgical lead 1600 is comprised of an integrated flexible panel 1602. In a preferred embodiment, the flexible panel 1602 is a medical-grade, inert, flexible polymeric material, as previously described. Integrated within the flexible panel are multi-duct leads 1608 and 1610. Each of the multi-duct leads 1608 and 1610 includes a central lumen 1698 and 1699, respectively. The central lumens include optical fibers 1611 and 1612, respectively. Each optical fiber terminates in a side-ignition fiber optic portion 1618 and 1619, respectively. The side-ignition fiber optic portions are configured as previously described. Each side-ignition fiber optic portion is disposed adjacent to an optical window 1621 and 1620, respectively. In a preferred embodiment, each of the optical windows is an integrally formed, optically transparent region of the flexible panel 1602.

[0148] Panel 1602 further includes electrode arrays 1604 and 1606. Each of electrode arrays 1604 and 1606 includes eight electrodes embedded in the surface of panel 1602 and having exposed surfaces on the exterior of the panel. In a preferred embodiment, the electrodes are a platinum-iridium alloy. As previously described, each of the electrodes is connected to exactly one lead contact via the conductors of the multi-duct lead body. Electrode array 1604 is connected to lead contact 1630. Electrode array 1606 is connected to lead contact 1632.

[0149] Each of the multi-duct leads 1608 and 1610 terminates in a ferrule 1690 and 1691, respectively, which is attached to and coupled to the optical fiber, as previously described.

[0150] 15B, the conductors of the multi-duct lead body are separate from side-ignition fiber optic portions 1618 and 1619 of optical manifolds 1653 and 1652, respectively. Each of electrode arrays 1604 and 1606 is connected to the conductors of one of conductor bundles 1640 and 1642, respectively, via electrical connections 1650 and 1651.

[0151] Panel 1602 further comprises a grid shield 1614. The grid shield 1614 comprises a generally flat flexible film integrally formed with both of the flexible panels. As previously mentioned, the grid shield may be coated with a reflective material adjacent to the optical fibers. As previously mentioned, the grid shield may be connected to a ground contact for further connection to the IPG ground.

[0152] Panel 1602 further includes reflectors 1616 and 1625 disposed adjacent side-ignited fiber optic sections 1618 and 1619, respectively. In a preferred embodiment, the reflectors are generally semi-cylindrical or parabolic. In another embodiment, the reflectors are flat, flexible panels. The reflectors serve to reflect light emitted from the side-ignited fiber sections away from the optical window and to focus incident light from the optical window onto the fiber for transmission to a detector within the IPG.

[0153] 16A, 16B, and 16C, an alternative embodiment of a surgical lead 1700 is described. The integrated panel 1702 is generally flat, polymeric, and rectangular, as previously described. Integrated within the integrated panel 1702 are multi-duct leads 1718, 1720, and 1722 with optical fibers 1736, as previously described. Each of the multi-duct leads has a proximal electrical contact individually connected to electrode arrays 1712, 1714, and 1716 via conductors, as previously described. The integrated panel 1702 further includes an optical window 1709 integrated into the panel-adjacent side ignition fiber portions 1730, 1732, and 1734, as previously described.

[0154] Composite reflector 1710 is comprised of a plurality of alternating parabolic surfaces, such as surfaces 1750, 1752, and 1754, and flat gap surfaces, such as surfaces 1756 and 1758. The parabolic and flat surfaces are preferably constructed of a flexible, inert plastic with sufficient rigidity to maintain a moderate degree of bending. In preferred environments, polyvinyl chloride is used. The inner surfaces of the parabolic surfaces 1751, 1753, and 1755, and the inner surfaces of the flat surfaces 1757 and 1759, are all coated with a reflective material, such as titanium dioxide. Inner surfaces 1751, 1753, and 1755 are positioned adjacent side-ignition fiber portions 1730, 1732, and 1734 and function as previously described.

[0155] In another preferred embodiment, composite reflector 1710 is grounded to the IPG case via a conductor in one of the multi-duct leads, as previously described.

[0156] 17A and 17B, an alternative embodiment of a surgical lead 1800 will be further described.

[0157] The integration panel 1802 is generally flat, polymeric, and rectangular, as previously described. The integration panel 1802 includes electrode arrays 1810 and 1812 connected to multi-duct leads 1814 and 1818, as previously described. The integration panel 1802 further includes integrally formed multi-duct leads 1814, 1816, and 1818, as previously described. Each of the multi-duct leads 1814, 1816, and 1818 includes an optical fiber 1850 with a side-firing fiber portion 1820, 1822, and 1824. Each optical fiber 1850 is positioned to terminate in a right-angle prism, such as right-angle prisms 1804, 1806, and 1808, which are positioned to direct light from optical windows 1811, 1813, and 1817 to the optical fibers or from the optical fibers to the optical windows, as the case may be.

[0158] Referring now to FIG. 18, a method 1900 for placing a surgical lead will be described.

[0159] In step 1902, a laminotomy is performed at the level of the segment corresponding to the somatic distribution of the patient's pain.

[0160] Electrodes are placed in the spinal canal at step 1904. Typically, the electrodes are placed in the dorsal epidural space by manually inserting the electrode array into the laminotomy space.

[0161] In step 1906, the electrodes are secured to fascia, ligaments, or adjacent bone.

[0162] In step 1908, an incision is made for the IPG.

[0163] In step 1910, the lead is tunneled subcutaneously from the electrode insertion site to the IPG pocket.

[0164] In step 1914, the multiduct lead is secured to the IPG header. If the fiber is not already secured to the multiduct lead, it can be inserted and secured in this step, as described below. In practice, the lead body, including the fiber subassembly, is threaded into the appropriate lead channel, bringing the proximal lead contact into electrical contact with the lead channel's angled coil spring. The multiduct lead advances within the lead channel until it encounters a full-conical centering surface 724, which guides the multiduct lead body along a cylindrical alignment surface 726 until it engages a stop surface 730 of an anchoring chamber 728. Simultaneously, the ferrule advances within the alignment cylinder 712 until it encounters a ferrule centering surface 716, which aligns the optical fiber within the buffer gap 734 with the optical window within the IPG casing adjacent the composite optoelectronic device 740. The multi-duct lead is secured in the lead channel by advancing anchor screw 708 using a torque limiting ratchet until it engages anchor ring 1410 .

[0165] In step 1916, the IPG is placed in the pocket.

[0166] In step 1918, the procedure ends.

[0167] Referring to FIG. 19, a preferred method 2000 of percutaneous lead placement is described.

[0168] In step 2002, a Tuohy needle and needle stylet are inserted into the spinal canal at the appropriate segment level.

[0169] In step 2004, the needle stylet is removed from the lumen of the Tuohy needle.

[0170] In step 2006, the percutaneous lead with attached stylet guide is inserted into the inner diameter of the Tuohy needle.

[0171] In step 2008, the percutaneous lead is guided to an appropriate location within the spinal canal using the stylet guide wire under fluoroscopy.

[0172] In step 2010, the stylet guidewire is removed from the stylet channel.

[0173] In step 2012, the optical fiber is inserted into the stylet channel as described above.

[0174] In step 2014, the Tuohy needle is removed, leaving the lead in place.

[0175] In step 2016, the proximal end of the percutaneous lead is secured to the IPG header as described above.

[0176] Referring now to FIG. 20, step 2012 of securing the optical fiber in the stylet channel of the lead will be further described.

[0177] In step 2102, semi-cylindrical sections 1461 and 1462 are aligned with the percutaneous lead body. In step 2104, semi-cylindrical sections 1461 and 1462 are assembled by press-fit. In step 2106, the proximal end of the percutaneous lead body is inserted into the alignment cavity of the threaded part, guided by a fulcrum conical lead centering surface 1463. An alignment surface 1467 aligns the multi-duct lead body with the alignment cavity 1498.

[0178] In step 2108, the optical fiber 1418 is inserted into the fiber alignment duct 1499, guided by the fulcrum conical fiber optic centering surface 1465. The optical fiber is then inserted into the stylet channel 1405 of the multi-duct lead body 1402 of the threaded component.

[0179] In step 2110 , the ferrule 1412 is threaded onto the optical fiber 1418 .

[0180] In an alternative embodiment, a stylet is placed in the fiber alignment duct and the stylet channel at this step, in which case the method ends here.

[0181] In step 2112, the threaded component is disassembled.

[0182] In step 2114, the half cylinder is removed from the assembled lead body and optical fiber.

Claims

1. A surgical lead wire, a flexible panel; a series of electrode arrays embedded within the flexible panel; a series of leads integrally formed with said flexible panel; a series of lumens; at least one lumen of a series of lumens in at least one lead of the series of leads; a set of conductors within the at least one lead of the set of leads; a series of contacts connected to the at least one lead of the series of leads; at least one conductor of the series of conductors connected between one contact of the series of contacts and one electrode array of the series of electrode arrays; a series of window portals formed in the flexible panel adjacent to and distal to the series of electrode arrays; a series of optical fibers, A series of side-illuminated sections and at least one optical fiber in the series of optical fibers having at least one side-illuminated portion in the side-illuminated portions; at least one optical fiber of the set of optical fibers within the at least one lumen of the set of lumens; the at least one side illuminating portion disposed adjacent to a window portal of the series of window portals; a set of ferrules; at least one ferrule of the series of ferrules disposed on the at least one optical fiber of the series of optical fibers; a planar flexible grid shield adjacent to said series of leads; and the flexible grid shield is made of a carbon fiber material and is grounded to the implantable pulse generator by one conductor of the series of conductors; At least one lead in the set of leads further comprises: a non-metallic conductive layer grounded to the implantable pulse generator; The flexible grating shield has a non-metallic reflective surface. Surgical leads.

2. 2. The surgical lead wire according to claim 1, A series of reflectors; at least one reflector in the series of reflectors adjacent to the at least one side-illuminated portion in the series of side-illuminated portions; A surgical lead wire having:

3. The surgical lead wire according to claim 1, further comprising: a series of diffusion chambers; at least one diffusion chamber in the series of diffusion chambers connected to the at least one lead in the series of leads; the at least one side-illuminated portion of the series of side-illuminated portions within the at least one diffusion chamber of the series of diffusion chambers; A surgical lead wire having the following features.

4. The surgical lead wire according to claim 3, further comprising: a series of internal reflective surfaces; at least one internal reflective surface of the series of internal reflective surfaces at a distal end of the at least one diffusion chamber of the series of diffusion chambers; A surgical lead wire having the following features.

5. 3. The surgical lead of claim 2, wherein at least one reflector in the series of reflectors is constructed from a non-metallic material.

6. 3. The surgical lead of claim 2, wherein at least one of the series of reflectors is TiO. ２ 1. A surgical lead wire, the surgical lead being a non-metallic substrate coated with

7. 3. The surgical lead of claim 2, wherein the series of reflectors are integrated into a reflective panel.

8. 3. The surgical lead of claim 2, wherein the series of reflectors further comprises: A surgical lead having a prism directed toward one of the series of window portals.

9. 2. The surgical lead of claim 1, wherein the series of conductors are arranged in an axially aligned radial pattern.

10. The surgical lead wire according to claim 1, further comprising: A surgical lead having a planar heat shield adjacent to the series of leads.

11. 2. The surgical lead of claim 1, wherein one optical fiber of said series of optical fibers is made of polymethylmethacrylate material.

12. 2. The surgical lead of claim 1, wherein the series of leads further comprises: a first pair of leads for transmitting a first optical signal; a second pair of leads for receiving a second optical signal; A surgical lead wire having the following features.

13. 2. The surgical lead of claim 1, wherein the series of leads further comprises: a first lead for transmitting a first optical signal; a second lead for receiving a second optical signal; A surgical lead wire having the following features.

14. 10. The surgical lead of claim 1, wherein at least one ferrule of the series of ferrules is spliced ​​to the at least one optical fiber of the series of optical fibers.

15. 1. A method for placing a surgical lead, comprising: providing a flexible panel having a series of window portals; providing a series of leads integrally formed with said flexible panel; providing a light diffusing cavity on at least one of the series of leads adjacent to at least one of the series of window panels; providing a series of lumens, at least one lumen of the series of lumens being within the at least one lead of the series of leads; providing a series of optical fibers; providing at least one optical fiber in the series of optical fibers having a side-illuminated portion disposed within the light-diffusing cavity; providing two or more metal contacts disposed at a proximal end of a lead body for providing electrical connection to the series of leads, the metal contacts being fixed to the exterior of the lead body with uniform axial distances between each metal contact along the lead body, the metal contacts being positioned to electrically contact a coil spring within a pulse generator casing header; providing a planar flexible grid shield adjacent to the series of leads; the flexible grid shield is made of a carbon fiber material and is grounded to the implantable pulse generator by one conductor of the series of conductors; At least one lead in the set of leads further comprises: a non-metallic conductive layer grounded to the implantable pulse generator; providing a flexible grating shield, the flexible grating shield having a non-metallic reflective surface; A method comprising:

16. 16. The method of claim 15, further comprising: placing the at least one optical fiber of the series of optical fibers within the at least one lumen of the series of lumens; placing a ferrule onto the at least one optical fiber of the series of optical fibers; A method comprising:

17. 16. The method of claim 15, The method includes disposing the side-illuminated portion within the light-diffusing cavity.

18. 16. The method of claim 15, securing leads of the set of leads in electrical contact with the coil spring within the pulse generator casing header.

Images