Not Applicable.
The invention relates to an improved system and/or method for treating chronic spinal pain comprising a surgical procedure either alone or in combination with a spinal procedure such as vertebral fusion with implantation of a neuromodulation device, wherein the surgical procedure includes lead placement with open physical and visual access to the region of the spine undergoing treatment and/or as a minimally invasive surgical procedure for placement of the lead in the absence of such physical and visual access to the target region.
Neuromodulation for the treatment of chronic spinal pain is a procedure that has been in use for decades. The procedure is generally prescribed to a patient only after they have gone through a spinal procedure that may involve vertebral fusion in an effort to mitigate and/or correct the supposed source of the pain. However, often such spinal procedures do not resolve the pain issues. After weeks, months and perhaps years of continued chronic pain and pain therapy through medications, including opioids, the patient may finally be prescribed neuromodulation for the treatment of chronic pain after failed back surgery.
The prior art neuromodulation systems include an implantable pulse generator (IPG) and one or more neurostimulation leads having a distal portion having one or more electrodes and a proximal portion for electrically coupling the electrodes to the implantable pulse generator. The lead is implanted via a tunneling method, without direct physical or visual access to the target nerve, such that the electrodes are advanced to a position at or near a target nerve and the implantable pulse generator is implanted in a pocket spaced from the target area.
Existing neuromodulation systems include: the Intellus™ and the Restore Sensor™ systems from Medtronic, PLC; the Spectra™ system from Boston Scientific, Inc; the Senza™ and Omnia™ systems by Nevro, Inc.; the Proclaim™ system by Abbot, Inc.
Problems with the prior art neuromodulation systems include difficulty in achieving satisfactory pain relief due to difficulties with lead placement relative to the nerve target, whether the nerve target is the spinal cord in the case of spinal cord stimulation system or the dorsal root ganglia in the case of dorsal root ganglia stimulation system. Additionally, there is a problem in the prior art of maintaining satisfactory pain relief over time due to lead migration, reduced patient response to a previously efficacious therapy, or due to implantation of the neuromodulation system weeks, months or years after a spinal fixation procedure, or implantation of the neuromodulation system at a different spinal level than the spinal fixation procedure, and other shortcomings that are addressed by the present invention. These problems of the prior art exist both in the case of spinal cord stimulation and dorsal root ganglia stimulation.
Accordingly, it would be highly advantageous to provide a surgical method and system that enables both a spinal procedure and neuromodulation system implantation within a single procedure.
It would be further highly advantageous to enable full physical and visual access to the associated spinal treatment site for placement of the surgical fusion device and the neuromodulation system.
It would be a further advantage to provide a surgical procedure that does not require advancement of an electrical lead through a patient's anatomy to reach the ultimate location of therapeutic efficacy.
It would be a further advantage to provide a surgical procedure and lead design and method of implantation that ensures optimal lead placement.
It would be a further advantage to provide a surgical procedure and lead design and neuromodulation system design that minimizes lead migration over time and/or minimizes loss of therapy over time for a previously efficacious therapy.
It would he a further advantage to provide implantation of the neuromodulation system during the open spinal procedure, wherein the neuromodulation system may generate electrical stimulation during and/or after the surgical procedure.
It would be a further advantage to provide the implanted neuromodulation system as described above and for use in generating electrical stimulation only if the patient experiences pain after the surgical procedure.
It would, alternatively, be advantageous to provide an implantation of the neuromodulation system that would remove the need for the patient to undergo a first spinal fixation surgery, a revision of the first spinal fixation surgery or a subsequent spinal fixation surgery for the treatment of chronic pain
It would further be advantageous to use the neuromodulation system in combination with a laminectomy procedure and/or prevent the need for a laminectomy procedure.
Various embodiments of the present invention address these, inter alia, issues.
The present invention provides an improved lead design and method for optimal lead placement during a single surgical method for implantation at a spinal treatment site that comprises both targeted vertebral and spinal levels to be treated, wherein the spinal levels comprise at least one dorsal root ganglion. Electrical fields may be generated and shifted in location to optimize stimulation targeting. A spinal treatment procedure is performed generally in combination with implantation of a neuromodulation system that may comprise placement of electrical lead(s) on the at least one dorsal root ganglion, wherein each lead is in operative connection with a pulse generator that may also be implanted during the surgical method. Electrical stimulation may be generated with the pulse generator through the electrical leads to the at least one dorsal root ganglion during and/or after the closure of the identified spinal treatment site.
The Figures and the detailed description which follow more particularly exemplify these and other embodiments of the invention.
While the invention is amenable to various modifications and alternative forms, specifics thereof are shown by way of example in the drawings and described in detail herein. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Optimal Lead Placement over the Dorsal Root Ganglia
In order to describe the embodiments referred to in
The dorsal root ganglion, as defined by the nodular shape having a first and second side, is understood to have a length ranging from 2 mm to 10 mm in the human anatomy, and a diameter ranging from 2 mm to 10 mm in the human anatomy. Given this range, one can appreciate that some subjects may even have a dorsal root ganglia with a diameter less than 2 mm or greater than 10 mm. Further, the actual diameter of a particular target dorsal root ganglia will depend upon the patient-specific anatomy and the spinal level of the dorsal root ganglia as each can be a factor in dorsal root ganglia size.
A target contact space is defined by the radial space extending from the axis of the dorsal root ganglia. The target contact space may further be defined by the radial space extending radially outwardly from the periphery of the dorsal root ganglia, in a direction perpendicular to the axis of the dorsal root ganglia.
Turning now to
A placement space is defined by the radial space extending from the periphery of the contact surface, perpendicular to the axis of the lead. The placement space extends along the entire length of the contact space of electrode from the first side to the second side of the electrode.
The lead has a proximal portion for electrically coupling each of the one or more electrodes to an implantable pulse generator. Each of the one or more electrodes is capable of being activated either alone or in combination with other electrodes to selectively deliver an electrical stimulation signal to an anatomical target in proximity to the one or more activated electrodes.
In the embodiments shown in
In one embodiment of the present invention, a lead 10 having two or more electrodes 12 is dimensioned and spaced such that only a single electrode 12 is positionable within the target contact area of the dorsal root. ganglia at a time. In one embodiment, the distance between adjacent electrodes along the length of the lead 10 is such that only a single one electrode 12 is positionable within the target contact space.
In an alternative embodiment of the present invention, the leads 10 may be spaced and dimensioned such that two or more leads 10 are capable of being simultaneously positioned within the target contact space of the dorsal root ganglion such that at least a portion of the contact surface of each of the two or more electrodes 12 is positioned and/or positionable within the target contact space.
One method for placing a lead 10 in accordance with the above embodiments is to provide direct open visual and physical access to the target dorsal root ganglia and directly place the lead, such lead 10 being any of the embodiments described herein or variations thereof, such that at least a portion of the contact. surface of only a single electrode 12 is positioned over the target contact space of the dorsal root ganglia.
Another method of placing the lead 10 in accordance with the present invention is to provide direct open visual and physical access to the target dorsal root ganglia such that the entire length of at least one electrode 12 is positioned within the target contact space defined by the dorsal root, ganglia.
Yet another method is to perform the above lead placement steps at a spinal treatment site in combination with a spinal fixation procedure. In such case, the treatment site is accessed as part of the spinal treatment procedure and the direct visual and physical access to the dorsal root ganglion is provided by virtue of the access to the treatment site created for the spinal treatment procedure. The lead 10 and associated at least one electrode 12 are placed at least partially within the target contact space under direct visual and physical access to at least a portion of the dorsal root ganglion during, after, or in combination with the spinal fixation procedure.
Where the target dorsal root ganglion is at the same spinal level as the spinal fixation then the lead can be placed in accordance with the embodiments of the present invention and lead migration is minimized and/or eliminated due to the spinal fixation procedure resulting in the implantation of fixation rods and screws that prevent movement and bending at the spinal level of the target dorsal root ganglion, and therefore, preventing or minimizing the forces that would otherwise potentially cause lead migration at a spinal level at which spinal fixation had not been performed.
Once the lead 10 is positioned over the target dorsal root ganglion in accordance with the embodiments provided herein, the proximal portion of the lead 10 being electrically coupled to the implantable pulse generator (IPG), the electrode 12 that is positioned over the dorsal root ganglion can be activated by programming of the implantable pulse generator to create an electrical stimulation field around the electrode 12 such as by designating the target electrode as the cathode 16. The anode 14 may then be designated by any conducting member so designated by the user, such as the implantable pulse generator IPG itself being the anode, the fixation rod being designated the anode, the pedicle screw being designated the anode or combinations thereof. Additionally or alternatively, any other additional electrode 12 may be designated as the anode. The neuromodulation electric field is shaped more monopolar/unipolar when the anode is at least two lengths of the target electrode away. The neuromodulation electric field is shaped as a bipolar field when the anode and cathode are less than that distance apart. Thus, in the case where a unipolar field is preferred, the electrode 12 designated as the anode 14, as programmed by the implantable neurostimulator (IPG), should be a distance of at least two lengths of the target electrode away so as to ensure that a generally spherical neurostimulation field is created by the target electrode. Conversely, in the case where a bipolar field is preferred, the electrode designated as the anode, as programmed by the implantable neurostimulator (IPG), should be a distance of less than two electrode lengths away from the target electrode.
As such, electrode 12 size and spacing will determine the neurostimulation field surrounding the dorsal root ganglion. An electrode 12 size of about 0.5 mm to about 10 mm is within the length of electrode contact areas anticipated by the present embodiments. As such, the spacing from one electrode 12 to the next would vary in accordance with the electrode size, as defined by its length.
By way of example, a first 12 electrode having a length of 1 mm may he spaced from a second electrode 12 having a length of 1 mm such that the first and second electrode are spaced from each other such that a center to center distance between the electrodes is less than or equal to 2 mm. For other electrode sizes, lengths, a proportional center-to-center distance would be used in order to provide a bipolar electrical field capability.
Field Shaping and Field Steering
As will be discussed in more detail below with reference to
The neurostimulation field settings can be programmed by the implantable pulse generator (IPG), and/or an associated patient and/or physician programmer. As shown, the neurostimulation field may be increased or decreased to various levels, the field lines indicating the distance at which a given neurostimulation field meets a minimal threshold to neuromodulate the neurons and/or cells within the defined neurostimulation field. Alternatively, the neurostimulation field can be adjusted in accordance with patient feedback such as alleviation of pain symptoms, presence or absence of paresthesia or other patient or physician articulated criteria. Alternatively, the neurostimulation pattern may be altered such that a particular target area of the dorsal root ganglion undergoes neuromodulation at higher or lower level of neuromodulation activation even where all of such levels of neuromodulation are above a threshold level. As such, the neurostimulation field can be adjusted according to a first level of neuromodulation activation, a second level of neuromodulation activation and additional levels of activation according to patient preference or sensation and/or in consideration of the battery longevity of the implantable pulse generator and/or other considerations alone or in combination.
It may be preferable that certain sub-sections of the dorsal root ganglia are desired to be stimulated and/or to avoid stimulation of certain sub-section of the dorsal root ganglia. For example, it may be desired that the neurostimulation field include a surface of the dorsal root ganglia or a deeper level of the dorsal root ganglia or the peripheral nerve section or the dorsal root section or neither or both depending once again on patient feedback and other considerations.
It may additionally or alternatively be preferable to provide or minimize neurostimulation of the patient anatomy around the dorsal root ganglia. For example, but not intended to be limiting, it may be beneficial to include the spinal root in the neurostimulation field or it may be beneficial to prevent the neurostimulation field from encompassing the spinal root, depending again on patient, physician, anatomical, practical and procedural feedback and limitations.
As shown in
Field Steering
In accordance with the above embodiments shown in
Field steering as that term is used herein allows an electric/neurostimulation field to be optimally positioned, shaped, located and/or moved or shifted between adjacent, or non-adjacent, electrodes thus allowing for more programmability with fewer electrodes. Certain embodiments allow the generated electric field to have an initial location along the lead, wherein the initial location comprises flowing current to certain electrodes along the lead that are designated as cathode(s) and as designated anode(s). This initial location of the generated electric/neurostimulation field obviously impacts certain tissue, e.g., the targeted tissue, e.g., DRG or dennatome, and does not impact (or impacts at a lesser stimulation level) other, perhaps non-targeted, tissue. The initial location of the generated electric field may be shifted along the lead to a second location by, inter alia, designating certain electrodes (different in combination that those in the initial location described above) as designated cathode(s) and designated anode(s). Because each electrode along the lead has its own electrical connection with the IPG, the electrodes may be independently selected/designated and energized by the IPG to create a plurality of serial electrical fields, each with a location that may differ from the location of other electrical field locations. As will now be clear, the generated electric/neurostimulation field location may be moved or shifted in a linear, non--linear, regular or random patterned fashion along the lead as the designated cathode(s) and anode(s) are changed.
As discussed above, the IPG may be programmed to select one, or more, of the electrodes along the lead as a cathode and an adjacent, or non-adjacent, electrode as an anode, thereby generating a spherical electrical field. In
In
In
The shape and size of the neurostimulation field can be steered according to the selection of one or more adjacent cathodes or cathodes within a field-effecting distance from one another. The selection of the ratio of energy (or amplitude) delivered to each of the one or more anodes and/or cathodes is selected in order to create a predetermined neurostimulation field location and/or shape in order to achieve a predetermined functional, clinical or performance criteria and/or neurostimulation field shape. By way of example, the use of two cathodes for field steering and/or field shaping may also result in a greater radial field of electrical stimulation from the center of the virtual electrode position along the axial length of the lead as compared to a single electrode.
In use, the implantable pulse generator is programmed via a physician and/or patient programmer to active certain electrodes of the lead as cathode and/or anode in accordance with predefined outcome criteria such as pain relief, battery longevity and other considerations either alone or in combination.
Novel Wave Forms
As discussed above with reference to
Once such neurostimulation field is determined based on patient feedback and other considerations, the wave form can be programmed into the implantable pulse generator to generate a waveform in accordance with patient, physician, functional and practical considerations.
The waveform may take any of the waveforms shown in
Waveforms may be delivered from a library of different waveforms, such as a tonic, burst, high frequency, low frequency, high amplitude, low amplitude, phase shifting, phase locking, phase changing waveform.
Alternatively, the waveforms may be delivered by altering various current waveform parameters without having a predetermined second waveform as a basis for altering the current waveform. In such case, there may be a window of acceptable phases, amplitudes, time periods and/or other parameters within which a new waveform must conform but need not be a predetermine or previously designed waveform, simply a waveform that is sufficiently different from the current waveform in order to provide a therapeutic effect, for example, or to minimize diminution of the therapeutic effect of the current waveform after a period of time.
By way of example, a first waveform may be programmed to be delivered to a target stimulation site for a first predetermined amount of time and then a second waveform may be programmed to be delivered to the target stimulation site for a second predetermined amount of time. Each of the waveforms may be fixed in terms of amplitude and duration or variable in amplitude and duration, but in either case are differentiated from each other such that the neurostimulation waveform at the first period of time is measurably different than the second neurostimulation waveform at the second period of time. Likewise, first and second periods of time may be of the same or differing in length.
The alternative cycle between one waveform and another may be repeated, or a series of non-repeating waveforms and repeating and/or non-repeating time periods may be utilized in accordance with the use and design of the neurostimulation system of the present invention.
The various potential waveforms and/or combinations of waveforms and waveform variables are illustrated in
These and additional control variables may be used to create predetermined waveforms, novel waveforms or combinations of a plurality of predetermined waveforms, or combinations of a plurality of novel waveforms, or mixed combinations of predetermined and novel variable and/or random waveforms.
Waveforms may have a predetermined fixed, repeating, non-repeating, random, non-random form including but not limited to: waveform shape such square, non-square rounded, saw tooth, sloping leading edge, sloping trailing edge, variations or fixed peak, variations or fixed adaptations, may utilized pre-condition pulses, hyperpolarize to make more excitable or depolarize to make less excitable. From a patient point of view, waveforms may be predetermined and/or randomized such that a neuron or group of neurons are or are not recruited via neurostimulation, are or not made more or less excitable to make it more or less likely to fire when modulated, do or do not induce paresthesia and the levels of effect of each of these on a. patient perception of paresthesia, pain, or other patient attributes.
The waveforms may then be titrated to patient perception, for example, providing sub threshold stimulation but resulting in pain relief or paresthesia.
Sensing plus Stimulation (Sensing, Analyzing, Copying and then Stimulating)
In yet another embodiment of the present invention, what is provided in
As shown in
This generated stimulation pattern may then be used to stimulate the painful (pathologic) dorsal root ganglion and/or nerve or nervous system structure. This signal would then be transmitted to the higher nervous system structures (higher neuronal structures, brain structures, etc. The rational for this being that the higher structures in the spinal cord and/or brain would not receive the signals and messages from the lower structures (more distal or peripheral structures) indicating pain. They would receive messages and signals that indicate no pain, much like being sent to the higher neuronal structures from the other (non-painful) side.
In another embodiment, illustrated in
Any of the one or more electrodes may be programmed to act either as a sensing 20 or as a stimulating 22 electrode by the IPG or the operator. Alternatively, a predetermined one or more electrodes may be sensing only electrodes while a predetermined one or more set of electrodes may be stimulation only electrodes.
Returning to
In one embodiment, the sensing time frame may be continuous wherein an electrical stimulation pattern is sensed by sensing electrodes 20 of the first lead 10 and then a corresponding electrical stimulation pattern is delivered to the stimulating electrodes 22 of the second electrode 10′ in an essentially continuous fast-following fashion.
In another embodiment, a sensing window is used, wherein a predetermined time of sensed electrical information is received by sensing electrodes 20 of the first electrode 10 and such pattern is then delivered in a repeating fashion to the stimulating electrodes 22 of the second lead 10′ for either a predetermined period of time at which time the process repeats with a new sensing time frame for new stimulation pattern creation.
In yet another embodiment, first and second leads 10, 10′ are placed on separate dorsal root ganglia. Rather than relying on sensing, the first lead 10 while placed on a healthy dorsal root ganglia will stimulate the health dorsal root ganglia in order to reduce the sensation of pain in the dorsal root ganglia that is associated with pain. Without being bound by theory, the intention is to provide a novel signal to the patient which distracts from the pain signals at the second target anatomical zone.
In yet another embodiment, the same lead 10 or 10′ may perform both a sensing function and an electrical stimulation function. Once the sensing function has been performed for a predetermined time frame, a “pain signal waveform” is sensed and then an electrical stimulation is delivered out of phase to the pain signal waveform in order to cancel out the pain signal waveform and therefore reduce the sensation of pain sensed by the patient.
In a further embodiment, either alone or in combination with the above, the lead is implanted at a dorsal root ganglion where a spinal fixation device has been implanted.
In another alternative embodiment of a sensing and neurostimulation system, a sensing of the electrical activity of the brain may be utilized as an input to the sensing-based programming of a neurostimulation output. The brain sensing may be a biomarker that allows for the titration of the neurostimulation signal, and/or the brain sensing can be used to determine a biomarker for use in optimizing the neurostimulation signal. The signal may be titrated based on patient sensation in order to either identify a normal biomarker, abnormal biomarker, ideal biomarker, or combinations thereof. The biomarker allows for sensing of a patient signal that is titrated to a patient sensation such as pain, such that sensing of the biomarker allows for closed-loop or open-loop programming of the neuromodulation parameters and electrode or virtual electrode position, waveform and other attributes in order to provide patient therapy.
Leg Pain Expressed After Completion of a Spinal Fixation Procedure
Therapies Utilizing Cross-Talking between Different Levels of Dorsal Root Ganglia
Further, reference is made to the following United States Patent References, the entire contents of which are incorporated herein by reference:
U.S. patent application Ser. No. 16/519,320 filed on Jul. 23, 2019 entitled METHOD FOR IMPLANTING A NEUROMODULATION SYSTEM AT A SPINAL TREATMENT SITE;
U.S. patent application Ser. No. 16/665,525 filed on Oct. 28, 2019 entitled SYSTEMS, DEVICES AND METHODS FOR IMPLANTABLE NEUROMODULATION STEMULATION; and.
U.S. patent application Ser. No. 16/409,616 filed on May 10, 2019 entitled SYSTEM, DEVICES, AND METHODS COMBINING SPINAL STABILIZATION AND NEUROMODULATION.
The various embodiments described herein can be used as a system or method either alone or in combination with the various elements, features and methods of other embodiments and/or modifications thereof, in accordance with the spirit of the present invention. By way of example, the embodiments of a lead and implantable pulse generated may be implanted individually at a spinal treatment site either alone or in combination with a spinal fixation device. Likewise the lead and implantable pulse generator may exhibit any of the various functions and methods described herein either alone or in combination with a spinal fixation device and either at the same spinal level as a spinal fixation device or at a different spinal level than the spinal fixation device.
The descriptions of the embodiments and their applications as set forth herein should be construed as illustrative, and are not intended to limit the scope of the disclosure. Features of various embodiments may be combined with other embodiments and/or features thereof within the metes and bounds of the disclosure. Upon study of this disclosure, variations and modifications of the embodiments disclosed herein are possible and practical alternatives to and equivalents of the various elements of the embodiments will be understood by and become apparent to those of ordinary skill in the art. Such variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention. Therefore, all alternatives, variations, modifications, etc., as may become to one of ordinary skill in the art are considered as being within the metes and bounds of the instant disclosure. Atty.
This application claims the benefit of U.S. provisional patent application No. 63/079555 filed on Sep. 17, 2020 and entitled LEAD DESIGN AND METHODS FOR OPTIMAL LEAD PLACEMENT AND FIELD STEERING, the entire contents of which is incorporated herein by reference.
Number | Date | Country | |
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63079555 | Sep 2020 | US |