Patent Application
20190151660
The present disclosure generally relates to a system and method to deliver electrical stimulation to treat pain; and more particularly, to a system and method to deliver electrical stimulation to treat pain following a procedure to amputate or remove a limb, extremity, or body part or portion thereof.
Amputation can become necessary for a variety of reasons including, but not limited to, trauma, cancer, infection, birth defect, or vascular disease. Amputation procedures often result in significant post-operative pain that can cause a delay in rehabilitation and impact the patient's ability to use a prosthesis or return to activities of daily living. Post-amputation pain may include pain in the residual limb, also called the stump, and/or pain in the phantom limb, which is the experience of sensations in a representation of the portion of the limb that is no longer present. While existing systems and techniques offer some relief and ancillary benefits to individuals requiring therapeutic relief, many issues with such systems exist. Therefore, there is a need for an improved system and method.
Amputees commonly experience acute and chronic post-amputation pain. Amputation leads to persistent pain in 70-90% of patients. This pain results in decreased quality of life, increased risk of depression, negative impacts on interpersonal relationships and negatively affects the ability to work. Both acute and persistent post-amputation pain are commonly managed with opioids that are associated with undesirable adverse effects such as nausea, vomiting, sedation, and respiratory depression. Other treatments for post-amputation pain may include non-narcotic medications, physical or psychological therapies, surface electrical stimulation, and spinal cord stimulation, all of which have practical limitations that prevent widespread use.
Undergoing a surgical procedure and recovering from it is generally a painful process, emotionally and physically. There remains a need in the art of surgical preparation and/or pain management for improved systems and methods to be used to ready an animal body, especially, a human, for surgery and/or to assist in the recovery of the body after a surgical procedure. Such assistance in recovery of the body after a surgical procedure may include measures to alleviate post-operative pain and to prevent the onset or development of chronic post-operative pain. There is, therefore, a need for an improved pain treatment system and method for relief of post-operative pain, especially pain following amputation surgery.
The following presents a summary of this disclosure to provide a basic understanding of some aspects. This summary is intended to neither identify key or critical elements nor define any limitations of embodiments or claims. Furthermore, this summary may provide a simplified overview of some aspects that may be described in greater detail in other portions of this disclosure.
An embodiment contemplates a system to alleviate pain following surgical amputation or removal of an extremity, limb, body part, or body tissue including any combination of the following features:
In another embodiment contemplates a system to alleviate pain after an amputation surgery including any combination of the following features:
Another embodiment contemplates a kit for treatment of pain from amputation surgery comprising any combination of the following features:
A still further embodiment contemplates a kit for treatment of pain from amputation surgery comprising any combination of the following features:
Another embodiment contemplates methods to alleviate pain following an amputation surgery based upon any combination of the following features:
Other features and advantages of the present teachings are set forth in the following specification and attached drawings. The following description and the drawings disclose various illustrative aspects. Some improvements and novel aspects may be expressly identified, while others may be apparent from the description and drawings.
The accompanying drawings illustrate various systems, apparatuses, devices and methods, in which like reference characters refer to like parts throughout, and in which:
Reference will now be made to exemplary embodiments, examples of which are illustrated in the accompanying drawings. It is to be understood that other embodiments may be utilized and structural and functional changes may be made. Moreover, features of the various embodiments may be combined or altered. As such, the following description is presented by way of illustration only and should not limit in any way the various alternatives and modifications that may be made to the illustrated embodiments. In this disclosure, numerous specific details provide a thorough understanding of the subject disclosure. It should be understood that aspects of this disclosure may be practiced with other embodiments not necessarily including all aspects described herein, etc.
As used herein, the words “example” and “exemplary” mean an instance, or illustration. The words “example” or “exemplary” do not indicate a key or preferred aspect or embodiment. The word “or” is intended to be inclusive rather an exclusive, unless context suggests otherwise. As an example, the phrase “A employs B or C,” includes any inclusive permutation (e.g., A employs B; A employs C; or A employs both B and C). As another matter, the articles “a” and “an” are generally intended to mean “one or more” unless context suggest otherwise.
Moreover, the terms “patient,” “animal” “animal body” and the like are employed interchangeably throughout the subject specification, unless context suggests otherwise or warrants a particular distinction among the terms. Still further, the terms “user,” “clinician,” “medical professional,” “doctor,” “surgeon,” and the like are employed interchangeably through the subject specification, unless context suggests otherwise or warrants a particular distinction among the terms.
“Logic” refers to any information and/or data that may be applied to direct the operation of a processor. Logic may be formed from instruction signals stored in a memory (e.g., a non-transitory memory). Software is one example of logic. In another aspect, logic may include hardware, alone or in combination with software. For instance, logic may include digital and/or analog hardware circuits, such as hardware circuits comprising logical gates (e.g., AND, OR, XOR, NAND, NOR, and other logical operations). Furthermore, logic may be programmed and/or include aspects of various devices and is not limited to a single device.
Any elements described herein as singular can be pluralized (i.e., anything described as “one” can be more than one) unless otherwise noted. Any species element of a genus element can have the characteristics or elements of any other species element of that genus. The described configurations, elements or complete assemblies and methods and their elements for carrying out the present teachings, and variations of aspects of the present teachings can be combined and modified with each other in any combination.
The present disclosure relates to systems and methods for placing one or more leads in tissues for providing electrical stimulation to the tissue to treat pain by providing an electrical stimulation device having at least one percutaneous lead adapted for insertion within tissue of an animal body and a pulse generator operatively coupled with the at least one lead, wherein the pulse generator is configured to stimulate at least one nerve innervating a region of pain following amputation surgery and/or surgery for removal of body tissue or portion thereof. The system and method may also generate comfortable sensations and/or pain relief in the region of the surgery, including sensations and/or relief perceived to be in the body tissues that were actually amputated/removed during that surgery.
A kit for treatment of pain following amputation surgery and/or surgery for removal of body tissue or a portion thereof is also contemplated. The kit may include a needle insertable into an animal body tissue, at least one percutaneous electrode lead operatively inserted into the needle, wherein the needle and at least one percutaneous lead are inserted into an insertion point of the animal body. The needle can be removed from the animal body tissue and the at least one percutaneous electrode lead may be retained within the animal body. A pulse generator is operatively coupled with the at least one electrode lead, wherein the pulse generator is configured to stimulate at least one nerve innervating a region of pain following an amputation surgery and/or surgery for removal of body tissue or a portion thereof.
Methods to alleviate pain following an amputation surgery and/or surgery for removal of body tissue or a portion thereof are also disclosed. One such method may include inserting at least one electrode/lead within a therapeutically effective distance from at least one nerve and applying electrical stimulation through the at least one electrode to affect the at least one nerve innervating a region of pain following the amputation surgery. In this method, the electrical stimulation does not cause pain.
The systems, methods, kits, and associated devices—as well as instructions for use of the same—may prevent the development of chronic post-amputation pain, for example phantom limb pain or residual limb pain. In each instance, at least one electrode may be inserted in a patient within a therapeutically effective distance from at least one nerve. Electrical stimulation is then applied through the at least one electrode without causing pain or impairing normal bodily functions. This stimulation affects the at least one nerve innervating a region of pain following the amputation surgery or a region that may develop multiple types of pain, such as but not limited to acute, post-surgical, sub-acute, transitional, and/or chronic pain following the amputation surgery.
I. The Peripheral Nervous System—Anatomic Overview
As generally shown in
The somatic nervous system (SNS) is the part of the peripheral nervous system associated with the voluntary control of body movements through the action of skeletal muscles, and with reception of external stimuli, which helps keep the body in touch with its surroundings (e.g., touch, hearing, and sight). The system includes all the neurons connected with skeletal muscles, skin and sense organs. The somatic nervous system consists of efferent nerves responsible for sending central nervous signals for muscle contraction. A somatic nerve is a nerve of the somatic nervous system.
A. Spinal Nerves
A typical spinal nerve arises from the spinal cord by rootlets that converge to form two nerve roots, the dorsal (sensory) root and the ventral (motor) root. The dorsal and ventral roots unite into a mixed nerve trunk that divides into a smaller dorsal (posterior) primary ramus and a much larger ventral (anterior) primary ramus. The posterior primary rami serve a column of muscles on either side of the vertebral column, and a narrow strip of overlying skin. All of the other muscle and skin is supplied by the anterior primary rami.
The nerve roots that supply or turn into peripheral nerves can be generally categorized by the location on the spine where the roots exit the spinal cord, i.e., as generally shown in
B. Nerves of the Sacral Plexus
The sacral plexus SCP (
1. The Sciatic Nerve
As shown in
The nerve gives off articular and muscular branches. The articular branches (rami articulares) arise from the upper part of the nerve and supply the hip-joint, perforating the posterior part of its capsule; they are sometimes derived from the sacral plexus. The muscular branches (rami musculares) innervate the following muscles of the lower limb: biceps femoris, semitendinosus, semimembranosus, and adductor magnus. The nerve to the short head of the biceps femoris comes from the common peroneal part of the sciatic, while the other muscular branches arise from the tibial portion, as may be seen in those cases where there is a high division of the sciatic nerve.
The muscular branch of the sciatic nerve SN eventually gives off the tibial nerve TN and common peroneal nerve CPN (all shown in
C. Nerves of the Lumbar Plexus
The lumbar plexus (see
1. The Iliohypogastric Nerve
The iliohypogastric nerve (see
2. The Ilioinguinal Nerve
The ilioinguinal nerve (see
3. The Lateral Cutaneous Femoral Nerve
The lateral cutaneous femoral nerve (see
4. The Obturator Nerve
The obturator nerve (see
5. The Femoral Nerve
The femoral nerve (see
The femoral nerve has anterior branches (intermediate cutaneous nerve and medial cutaneous nerve) and posterior branches. The saphenous nerve (branch of the femoral nerve) provides cutaneous (skin) sensation in the medial leg. Other branches of the femoral nerve innervate structures (such as muscles, joints, and other tissues) in the thigh and around the hip and knee joints. As an example, branches of the femoral nerve innervate the hip joint, knee joint, and the four parts of the Quadriceps femoris (muscle): Rectus femoris (in the middle of the thigh) originates on the ilium and covers most of the other three quadriceps muscles. Under (or deep to) the rectus femoris are the other three of the quadriceps muscles, which originate from the body of the femur. Vastus lateralis (on the outer side of the thigh) is on the lateral side of the femur. Vastus medialis (on the inner part thigh) is on the medial side of the femur. Vastus intermedius (on the top or front of the thigh) lies between vastus lateralis and vastus medialis on the front of the femur. Branches of the femoral nerve often innervate the pectineus and sartorius muscles.
D. Nerves of the Brachial Plexus
1. Median Nerve
The median nerve MN originates from the lateral and medial cords of the brachial plexus BP (
2. Radial Nerve
The median nerve MN supplies the anterior portion of the arm and the radial nerve RN supplies the posterior portion of the limb. It originates from the posterior cord of the brachial plexus (
3. Ulnar Nerve
The ulnar nerve UN originates from part of the medial cord of the brachial plexus and descends on the posteromedial side of the humerus (
4. Axillary Nerve
The axillary nerve AN originates from the posterior cord of the brachial plexus below the shoulder in the axilla (or armpit) (
5. Musculocutaneous Nerve
The musculocutaneous nerve MCN is derived from the lateral cord of the brachial plexus. The nerve typically courses between the biceps brachii and brachialis muscles (
E. Trunk Nerves
1. Intercostal Nerve
The intercostal nerves arise from the thoracic spinal nerves from T1 to T11. The intercostal nerves generally innervate the walls of the thorax and the thoracic pleura, and nerves arising from lower thoracic levels (level 7-11) also supply the abdominal wall and abdominal peritoneum. The exact function, location and course, and structures innervated vary depending on the thoracic level of the nerve, but the intercostal nerves are mixed nerves, with both motor and sensory function.
2. Intercostobrachial Nerve
The intercostobrachial nerves are cutaneous branches of the intercostal nerves. Two levels in particular are likely to have intercostobrachial nerves. The second intercostobrachial nerve arises from the lateral cutaneous branch of the second intercostal nerve, crossing the axilla and supplying skin on the upper half of the medial and posterior arm. This nerve is often the source of the referred cardiac pain. The third intercostobrachial nerve arises from the lateral cutaneous branch of the third intercostal nerve, supplying filaments to the axilla and medial side of the arm.
II. The System
Shown in
Amputation is the removal of part of the body, and is commonly perceived as relating to amputation of extremities, limbs, or portions of extremities or limbs. However, it is to be appreciated that other parts of the body (e.g., nerve, muscle tissue, adipose tissue, connective tissue, bone, ligaments, tendons, joints, organs, masses (including both cancerous masses and non-cancerous masses), and other structures or tissues in the body) can be removed and/or amputated in whole and/or in part and are included as part of this disclosure. The removal or amputation of any body part(s) or tissue(s) can lead to significant pain, disability, dysfunction, or loss of function. The pain caused by, anticipated or expected from, and/or following the removal or amputation of the body part(s) or tissue(s), which may include an extremity, limb, appendage, part of an extremity, limb, or appendage, and/or a part of the body which is not an extremity, limb, appendage, or part of an extremity, limb, or appendage and is inside the body in whole or in part (such as a nerve, muscle tissue, adipose tissue, connective tissue, bone, ligaments, tendons, joints, organs, masses (including both cancerous masses and non-cancerous masses), and other structures or tissues in the body) may be treated and reduced or relieved by the present invention. The reduction and/or relief of pain provided by the present disclosure following amputation or removal of the body part or tissue may then lead to reduction of interference of pain in daily or usual activities, reduction of disability, improvement in function (without functional nerve stimulation at a motor point), and/or improvement in quality of life.
A. Stimulation of Peripheral Nerves
The peripheral nerve system, device, method, and instructions for use of systems, devices, and/or methods incorporate features of the present teachings. The system, device, method, and instructions for use of systems, devices, and/or methods may identify a region where there is a local manifestation of pain. The system, device, method, and instructions for use of systems, devices, and/or methods may also identify a region where there may be a manifestation of chronic pain at a later time, for example after an amputation surgery. The region of pain may comprise any appropriate portion of the body, e.g., tissue, skin, bone, a joint, muscle, or an appropriate portion of the body that was removed during amputation surgery or other surgical removal of tissue.
The system, device, method, and instructions for use of systems, devices, and/or methods may identify one or more spinal nerves located distant (e.g., any combination of one tenth increments between 0.5 cm and 3.0 cm) from the region where pain is manifested, through which neural impulses comprising the pain pass. A given spinal nerve that is identified may comprise a nerve trunk located in a nerve plexus, or a division and/or a cord of a nerve trunk, or a nerve branch, or a nerve plexus provided that it is upstream or cranial of where the nerve innervates the region affected by the pain. Table 1 provides non-limiting examples of regions of pain that may be innervated by specific nerves.
The given spinal nerve may be identified by medical professionals, doctor, surgeon or clinician using textbooks of human anatomy along with their knowledge of the site and the nature of the pain or injury, as well as by physical manipulation and/or imaging, e.g., by ultrasound, fluoroscopy, or X-ray examination, of the region where pain is manifested. A desired criterion of the selection may include identifying the location of tissue in a therapeutically effective distance (e.g., any combination of one tenth increments between 0.5 cm and 3.0 cm) from the nerve or passage, which tissue may be accessed by placement of one or more stimulation electrodes 116, aided if necessary by ultrasonic or electro-location techniques. A therapeutically effective distance may be defined to mean the placement of a lead adjacent to a nerve, preferably at a distance remote or removed from the nerve (e.g., between 0.1 cm and 4.0 cm, between 0.2 cm and 3.5 cm, between 0.5 cm and 3.0 cm, and/or greater than 0.1 cm or 0.2 cm) so as to allow preferential activation of targeted fibers without activation of non-target fibers. The nerve identified may comprise a targeted peripheral nerve. The tissue identified may comprise the “targeted tissue.” See Table 1 for further details.
The electrical stimulation device 102 may include one or more leads 112 having one or more electrodes 116 adapted for insertion into in any tissue of the body in electrical proximity but away from nerves. In a preferred embodiment, the electrical stimulation device 102 may include a single percutaneous lead 112 with a single electrode 116 on the percutaneous lead 112 such that the location of the percutaneous lead 112 determines the location of the one electrode 116 relative to the target nerve. This location of lead(s) 112 may improve recruitment of targeted nerves for therapeutic purposes, such as for the treatment of pain. In such embodiments, the electrode 116 may be integrally formed with the lead 112 or may be monolithically formed with the lead 112.
The electrodes 116 of the electrical stimulation device 102 may be percutaneously inserted using the percutaneous lead(s) 112. The system and method may place the one or more leads 112 with its electrode 116 in the targeted tissue in electrical proximity to but spaced away from the targeted peripheral nerve. The system, device, or method may apply electrical stimulation through the one or more stimulation electrodes 116 to electrically activate or recruit the targeted peripheral nerve that conveys the neural impulses comprising the pain to the spinal column.
Electrical stimulation of the peripheral nerve may generate comfortable sensations, or paresthesia, in the region of innervation of the nerve, which may include body tissue (limb, extremity, portion of a limb or extremity, or other type of tissue) that was surgically removed or amputated. Stimulation may generate a perception of sensation from tissue that is no longer present after surgical removal, and the activation of the peripheral nerve to generate comfortable sensations may offset painful signals caused by the amputation or surgery. Activation of the peripheral nerve to generate comfortable sensations may reduce pain in acute or subacute setting after amputation or surgery to remove tissue, and/or may prevent the development of chronic pain in the phantom (e.g., the tissue that was surgically removed) or the remaining tissue in the innervation region of the targeted peripheral nerve. Stimulation may also be delivered so as to provide pain relief without evoking comfortable sensations or paresthesia. Stimulation may be delivered using sub-threshold (i.e., below the threshold for sensation or perception) or other parameters that provide relief of pain without producing sensations or paresthesia.
The paresthesia and pain relief produced by this electrical stimulation is unexpected when compared to previously known electrical stimulation techniques. These previous schemes addressed scenarios where pain relief is either provided to existing body tissue and/or to body tissue proximate to replacement objects (e.g., an artificial joint). In the present teachings, tissue is gone and not replaced by natural or artificial structures, so there is an absence of normal/healthy inputs to the central nervous system leading to imbalance between noxious/non-noxious inputs. Stated differently, the system, device, and methods disclosed herein deliver “normal” or non-painful or non-noxious neural input to rebalance the signals from the periphery to the central nervous system to reduce pain and to prevent the development of chronic pain.
As used herein, “comfortable sensations” generally means that pain levels, as experienced by the patient, do not change or, more preferably, decrease over a given period of time. Thus, any standard metric for pain can be employed at selected intervals, during the treatment and/or over a period of treatments. The pain level trend over that period is indicative of comfortable sensations. Other non-quantitative feedback, again provided by a given patient, also may augment or provide a further definition of “comfortable sensations.” Still other indicators include reports of tingling, paresthesia, and the like. In some cases, it may even be possible to use medical instrumentation to detect and/or quantify responses within the patient's body that are suggestive of pain or a lack thereof.
The system, device, method, and instructions for use of systems, devices, and/or methods may apply electrical stimulation to peripheral nerves throughout the body, including, without limitation, the body of a person. By way of a non-limiting example, the peripheral nerves may comprise one or more spinal nerves in the brachial plexus, to treat pain in the shoulders, arms, and hands after amputation (see
The system, device, method, and instructions for use of systems, devices, and/or methods may reduce post-amputation pain by applying electrical stimulation to one or more peripheral nerves throughout the body before, during, and/or after the amputation. Therapy may be applied before, during, and/or after the resulting pain (i.e., post-amputation pain) develops, including in the acute, sub-acute, or chronic phases after amputation. The present system is designed to deliver therapy to relieve pain before, during, and/or after amputation, and may also be applied in a combination of those times, either continuously or intermittently. As a non-limiting example, the system, devices, methods, and instructions are designed to deliver therapeutic stimulation (e.g., electrical stimulation of the nerve of which a portion will be amputated) before amputation and after amputation. The therapeutic stimulation may be active prior to the amputation surgery, optionally turned off/deactivated during the surgery, and turned on/activated during and/or at some designated time following the surgery. Also, placement of electrical stimulation system may occur before or in the acute phase after amputation surgery (e.g., where tissue is being removed permanently).
The system, device, method, and instructions for use of systems, devices, and/or methods apply electrical stimulation to one or more peripheral nerves throughout the body to enable comfortable sensations to be evoked in the region that will be amputated in the distribution of the amputated nerve. Neural signals will be evoked by the therapeutic stimulation and sent to the central nervous system to decrease the perception of pain and maintain a balanced neural state. That is, the present system generates comfortable sensations to balance and/or override the uncomfortable and painful sensations that can accompany an amputation. By providing augmented neural input and/or drive and/or comfortable sensations from the periphery that signal to the central nervous system where noxious and/or painful and/or uncomfortable stimuli are processed, a reduction or elimination of pain can be achieved. If the augmented neural input is delivered while the amputation heals, the present system may prevent, reduce, and/or mitigate pain or the development of pain in the acute, sub-acute, or chronic phases after amputation. Thus, the present system enables therapeutic stimulation to be delivered to prevent, mitigate, or reduce the development of chronic pain.
The therapeutic stimulation may be delivered with a temporary or permanent fully implantable system, which could include a fully implantable lead and an implantable pulse generator (IPG) which may be controlled by external devices (such as a patient and/or clinician programmer and/or controller). The IPG may be powered by a(n) internal source(s), such as a rechargeable battery, a primary cell or non-rechargeable battery, or other means. The implantable system may also be powered by external sources, including an external pulse transmitter, or other means. The therapeutic stimulation may also be delivered with a temporary or permanent external (e.g., not implanted) system, which could include a fully implantable or percutaneously implanted lead and an external pulse generator (EPG) which may be controlled directly by controls on the EPG or by external devices (such as a patient and/or clinician programmer and/or controller). The EPG may be powered by a(n) internal source(s), such as a rechargeable battery, a primary cell or non-rechargeable battery, or other means.
For example, if the big toe (or great toe) is the location of pain in the residual limb (i.e., the stump) and/or the phantom limb (i.e., the amputated toe) following an amputation surgery, the system, device, and method may identify and stimulate the deep branch of the common peroneal nerve at a location upstream or cranial of where the nerve innervates the muscle or skin of the pinky finger, e.g., in the ankle and/or calf, or may identify and stimulate the sciatic nerve or another nerve trunk even further upstream of the deep peroneal nerve at the knee, thigh, or upper leg. If electrical stimulation activates the target peripheral nerve sufficiently at the correct intensity, then the patient will feel a comfortable tingling sensation, which may also be called paresthesia, in the same region as their pain, which overlaps with the region of pain and/or otherwise reduces pain. Further, if the big toe is the location of an amputation surgery, the system, device, and method may identify and stimulate a target peripheral nerve such as the deep branch of the peroneal nerve sufficiently so as to generate a comfortable tingling sensation or paresthesia before the amputation surgery, which overlaps with the area of potential development of chronic pain and prevents the subsequent development of chronic pain.
The system, device, method, or instructions for use of the system, device, or method may also be used to prevent and/or relieve other effects that patients may experience before, during, or after an amputation surgery. Non-limiting examples of such effects include depression, disability due to pain, pain interference with function or daily activities of living. The present system may therefore improve function and other qualities of life.
It is to be appreciated that the sensation could be described with other words such as buzzing, thumping, etc. Evoking comfortable sensations or paresthesia in the region of pain confirms correct placement of the lead(s) 112 and indicates stimulus intensity is sufficient to reduce pain. Inserting the lead(s) 112 percutaneously may allow the lead(s) 112 to be placed quickly and easily. Placing the lead(s) 112 in a peripheral location, i.e., tissue, where it is less likely to be dislodged, may address lead migration problems of spinal cord stimulation that may otherwise cause decreased coverage of comfortable sensations or paresthesia, decreased pain relief, and the need for frequent patient visits for reprogramming.
Placing the lead(s) 112 percutaneously in tissue with the electrode(s) in proximity to but spaced away from the targeted peripheral nerve may also minimize complications related to lead placement and movement. In a percutaneous system, the lead(s) 112 may be configured as a coiled fine wire electrode lead. This configuration may be used because it is minimally-invasive and well suited for placement in proximity to a peripheral nerve. The lead(s) 112 may be sized and configured to withstand mechanical forces and resist migration during long-term use, particularly in flexible regions of the body, such as the shoulder, elbow, and knee.
The lead(s) 112 may include a fine wire electrode 116 (as
The conduction location or electrode 116 may include a de-insulated area of an otherwise insulated conductor that may run the length of an entirely insulated electrode or a portion thereof. The de-insulated conduction region of the conductor may be formed differently, e.g., it may be wound with a different pitch, or wound with a larger or smaller diameter, or molded to a different dimension. The conduction location or the electrode may include a separate material (e.g., metal or a conductive polymer) exposed to the body tissue to which the conductor of the wire is bonded.
The lead(s) may be provided in a sterile package 200 (see
Embodiments of the lead 112 shown in
The electrode 116 may also include, at its distal tip, an anchoring element 124. In the illustrated embodiments, the anchoring element 124 may take the form of a simple barb or bend (see also
The anchoring element 124 may be sized and configured so that, when in contact with tissue, it takes purchase in tissue, to resist dislodgement or migration of the electrode 116 out of the correct location in the surrounding tissue. Desirably, the anchoring element 124 may be prevented from fully engaging body tissue until after the electrode 116 has been correctly located and deployed.
Alternatively, or in combination, stimulation may be applied through any type of nerve cuff (spiral, helical, cylindrical, book, flat interface nerve electrode (FINE), slowly closing FINE, etc.), paddle (or paddle-style) electrode lead, cylindrical electrode lead, echogenic needle (i.e., visible under ultrasound) and/or other lead that is surgically or percutaneously placed within tissue at the target site. The lead 112 may include an anchoring element 124 in the form of a simple barb or bend to maintain the lead 112 in the tissue at the target site at an appropriate therapeutic distance from the targeted peripheral nerve.
In a preferred embodiment, the lead(s) 112 may exit through the skin and connect with one or more external electrical stimulation devices 102 (this approach is shown in
The introducer needle 120 may be made from conductive and/or non-conductive materials, with its stimulating portion of the lead 112 (e.g., the electrode 116) housed inside. This stimulating portion may protrude from the end of the introducer needle 120 itself so as to come into contact with the body tissue in which the lead 112 is inserted. The distal end of the electrode 116 may also protrude from the end of the introducer needle 120 in the same manner. The introducer needle 120, lead 112, and/or electrode 116 may then be connected to an electrical stimulation device, such as an external pulse generator (e.g., see
The introducer needle 120 may be sized and configured to be bent by hand prior to its insertion through the skin. This may allow the physician to place the lead(s) 112 in a location that is not in an unobstructed straight line with the insertion site. The construction and materials of the introducer needle 120 may allow bending without interfering with the deployment of the lead(s) 112 and withdrawal of the introducer needle 120, leaving the lead(s) 112 in the tissue.
Representative lead insertion techniques will now be described to place an electrode 116 and lead 112 in a desired location in tissue in electrical proximity to but spaced away from a peripheral nerve. In the preferred embodiment, a single lead 112 may be placed to provide pain relief by targeting the peripheral nerve that innervates the region of pain. It is this placement that may make possible the stimulation of the targeted nerve or peripheral nerves with a single lead 112 to provide pain relief. It may also be desirable to place multiple leads to target a single peripheral nerve, for example by placing one lead medial to and one lead lateral to (or one lead superficial to and one lead deep to) a targeted peripheral nerve to activate target nerve fibers distributed throughout the nerve rather than preferentially activating nerve fibers on one side of the nerve. It may also be desirable to place multiple leads to target multiple peripheral nerves (using one or multiple leads for each targeted nerve) to provide pain relief in multiple regions of pain or in a region of pain that spans the regions of innervation of multiple peripheral nerves or branches of peripheral nerves.
To determine the optimal placement for the lead 112, test stimulation may be delivered through a test needle, including but not limited to those described in U.S. patent application Ser. No. 15/388,128, filed on Dec. 22, 2016 and incorporated by reference herein (along with any other applications or documents identified and incorporated by reference in that original document). These and other test needles may include one or more electrodes and/or be made from conductive material(s). The test needle may be selectively, electrically insulated to create a stimulating surface or surfaces on or near its distal tip, whereas the proximal tip has a hub, plug, and/or other connection mechanisms to allow the test needle to operate in concert with an external stimulation device, such as a pulse generator. These types of test needles may be used because they may be easily repositioned until the optimal location to deliver stimulation and generate paresthesia is determined. Alternatively, in some embodiments, the introducer or test needle may carry with the stimulation lead/electrode.
At least one lead(s) 112 may be placed in tissue near a targeted peripheral nerve (e.g., 0.1 cm to 10 cm with a preferred range between 0.5 cm and 3.0 cm remote from the targeted peripheral nerve). The lead(s) 112 may be inserted via the introducer needle 120 in any appropriate manner, which may be in some exemplary embodiments similar in size and shape to a hypodermic needle. The introducer needle 120, however, may be any size. By way of a non-limiting example, the introducer needle 120 may range in size from 17 gauge to 26 gauge. Before inserting the introducer needle 120, the insertion site may be cleaned with a disinfectant (e.g., Betadine, 2% Chlorhexidine/80% alcohol, 10% povidone-iodine, or similar agent). A local anesthetic(s) may be administered topically and/or subcutaneously to the area in which the electrode 116 and/or introducer needle 120 will be inserted.
The position of the electrode(s) 116 on the test needle and/or on the lead 112 itself may be checked by visualizing the test needle or introducer needle 120 using imaging techniques, such as ultrasound, fluoroscopy, or X-rays. Following placement of the lead(s) 112, the portion of the lead(s) 112 which exit the skin may be secured to the skin using covering bandages and/or adhesives or any other appropriate method and mechanism, as shown in
Electrical stimulation may be applied to the targeted peripheral nerve during and after placement of the electrode 116. Electrical stimulation may be applied to the targeted peripheral nerve through the electrode 116 while the patient describes the sensations and location of the sensations that are generated by the stimulation. The intensity of the stimulation may be increased or decreased to change the sensations and the location of sensations reported by the patient. When this method is used during the placement of the electrode 116, the sensations and location of sensations reported by the patient may also be modified by changing the location of the electrode 116 placement near the targeted peripheral nerve (e.g., 0.1 cm to 10 cm with a preferred range of 0.5 cm to 3.0 cm remote from the targeted nerve). This method may be used to determine whether stimulation of the targeted peripheral nerve can generate comfortable sensations or paresthesia that overlap with the region of pain and/or reduce pain.
In a percutaneous system (as
If the clinical screening test is successful, the patient may proceed to treatment with an external pulse generator or external electrical stimulation device 102 (as shown in
Electrical stimulation may be applied between the lead 112 and return electrode(s) 116 (monopolar mode). Regulated current may be used as a type of stimulation, but other type(s) of stimulation (e.g., non-regulated current such as voltage-regulated) may also be used. Multiple types of electrodes may be used, such as surface, percutaneous, and/or implantable electrodes.
In embodiments of a percutaneous system, the surface electrode(s) 114 may serve as the anode(s) (or return electrode(s)). The surface electrodes 114 may be a standard shape or they may be modified as appropriate to fit the contour of the skin. When serving as a return electrode(s) 114, the location of the electrode(s) 116 may not be critical and may be positioned anywhere in the general vicinity.
The electrode 116 and lead 112 may be placed via multiple types of approaches. By way of a non-limiting example, when the targeted peripheral nerve includes one or more nerves of the lumbar plexus or sacral plexus, the approach may be either an anterior (shown in
In other embodiments, when the targeted peripheral nerve includes the sciatic nerve (see
The landmarks for the transgluteal approach may include the greater trochanter and the posterior superior iliac spine. The introducer needle 120 may be inserted distal to the midpoint between the greater trochanter and the posterior iliac spine (e.g., approximately 2 cm to 6 cm distal, preferably 4 cm, in a preferred embodiment). As a non-limiting example of patient positioning, the patient may be in a lateral decubitus position and tilted slightly forward. The landmarks for the subgluteal approach may include the greater trochanter and the ischial tuberosity. The introducer needle 120 and, by extension, either or both of the test electrodes and the lead 112 and its associated electrode(s) 116, are inserted distal (e.g., approximately 2 cm to 6 cm, preferably 4 cm, in the preferred embodiment) to the midpoint between the greater trochanter and the ischial tuberosity.
By way of a non-limiting example, when the targeted peripheral nerve includes the femoral nerve (see
The size and shape of tissues, such as the buttocks, surrounding the target nerves may vary across subjects, and the approach may be modified as appropriate to accommodate various body sizes and shapes to access the target nerve. As non-limiting examples, the angle of needle insertion, depth of needle insertion, proximal or distal location of insertion on an extremity, or location of lead or electrode placement relative to certain fascial planes, muscular or bony landmarks, or the targeted peripheral nerve may be modified as appropriate.
Introducer needle 120 placement may be guided by the individual's report of stimulus-evoked sensations (paresthesia) as the introducer needle 120 is placed during test stimulation.
More than a single lead 112 may be placed around a given peripheral nerve, using either an anterior approach (e.g., femoral nerve) or a posterior approach (e.g., sciatic nerve). For example, multiple leads may be used to target a single peripheral nerve if one lead produces only partial coverage of the region of pain and the remainder of the region of pain is in the innervation area of the same targeted nerve. Multiple leads may be placed around the same nerve, for example by placing one lead medial to and one lead lateral to, or one lead superficial to and one lead deep to, or in some other pattern or arrangement around the targeted nerve. It may also be desirable to place multiple leads to target multiple peripheral nerves or branches of peripheral nerves, for example to provide pain relief in one or more multiple regions of pain that exist in or span the regions of innervation of multiple peripheral nerves or branches of peripheral nerves.
As
Control of the electrical stimulation device (e.g., the pulse generator) and its stimulation parameters may be provided by one or more external controllers. Alternatively, a controller may be integrated with the external electrical stimulation device 102. The implanted pulse generator external controller (i.e., clinical programmer) may be a remote unit that uses RF (Radio Frequency) wireless telemetry communications (rather than an inductively coupled telemetry) to control the implanted pulse generator. The electrical stimulation device 102 may use passive charge recovery to generate the stimulation waveform, regulated voltage (e.g., 10 mV to 20 V), and/or regulated current (e.g., about 10 mA to about 50 mA). Passive charge recovery may be one method of generating a biphasic, charge-balanced pulse as desired for tissue stimulation without severe side effects due to a DC component of the current.
The neurostimulation pulse may be monophasic (anodic or cathodic), biphasic, and/or multi-phasic. In the case of the biphasic or multi-phasic pulse, the pulse may be symmetrical or asymmetrical. Its shape may be rectangular or exponential or a combination of rectangular and exponential waveforms. The pulse width of each phase may range between e.g., about 0.1 μsec. to about 1.0 sec., as non-limiting examples. Changes in the pulse width of each phase may change the perception of the stimulation, comfort of the sensations from stimulation, or location of sensations from the stimulation that are sensed, described, or reported by the patient.
Pulses may be applied in continuous or intermittent trains (i.e., the stimulus frequency changes as a function of time). In the case of intermittent pulses, the on/off duty cycle of pulses may be symmetrical or asymmetrical, and the duty cycle may be regular and repeatable from one intermittent burst to the next or the duty cycle of each set of bursts may vary in a random (or pseudo random) fashion. Varying the stimulus frequency and/or duty cycle may assist in warding off habituation because of the stimulus modulation. Habituation of a patient to the sensations from stimulation can result in a decrease in the perceived intensity of stimulation. Avoiding habituation may be desirable to ensure that patient sensations are maintained at a perceived intensity that has a therapeutic effect.
The stimulating frequency may range from e.g., about 1 Hz to about 300 Hz. The frequency of stimulation may be constant or varying. In the case of applying stimulation with varying frequencies, the frequencies may vary in a consistent and repeatable pattern or in a random (or pseudo random) fashion or a combination of repeatable and random patterns. In the case of applying stimulation with constant frequency, the pattern of pulses may be a repeated train of pulses with regular intervals selected from a range (e.g., 1 pulse per second up to about 300 pulses per second).
In an embodiment, the stimulator may be set within a range of intensities (e.g., any combination of two whole integers between 1.0 and 30.0 mA and, separately, between 10 and 200 microseconds, so as to form lower and upper limits for each) and frequencies (e.g., any combination of two whole integers between 1 and 100 Hertz, again forming lower and upper limits to the ranges contemplated and expressly disclosed herein).
The distance between the targeted nerve and the lead/electrode must be sufficient to activate the targeted nerve (as noted above, preferably falling between 5.0 to 30 mm but also including any combination of numbers taken to the hundredths decimal place between 0.001 and 100.00 millimeters) away from the targeted peripheral nerve. As non-limiting examples, the lead could be placed at 0.03 mm, 6.23 mm, or 99.99 mm away from the targeted nerve, so long as the nerve is activated and the lead avoids physical contact of any portion of the electrode (i.e., the exposed, stimulating surface) with the targeted nerve. As noted throughout, and particularly in this paragraph, any disclosed range or combination of ranges may display inherent advantages in comparison to the previous teachings in this field.
If the stimulus intensity is too great, it may generate muscle twitch(es) or contraction(s) sufficient to disrupt correct placement of the lead 112. If stimulus intensity is too low, the lead 112 may be advanced too close to the targeted peripheral nerve (beyond the optimal position), possibly leading to incorrect guidance, mechanically evoked sensation (e.g., pain and/or paresthesia) and/or muscle contraction (i.e. when the lead touches the peripheral nerve), inability to activate the target nerve fiber(s) without activating non-target nerve fiber(s), improper placement, and/or improper anchoring of the lead 112 (e.g., the lead 112 may be too close to the nerve and no longer able to anchor appropriately in the muscle tissue).
Patient sensation may instead be used to indicate electrode 112 location relative to the targeted peripheral nerve as indicator(s) of lead placement (distance from the peripheral nerve to electrode contact). Any combination of stimulus parameters that evoke sensation(s) may be used. The stimulation parameters may include, but are not limited to frequency, pulse duration, amplitude, duty cycle, patterns of stimulus pulses, and waveform shapes. Some stimulus parameters may evoke a more desirable response (e.g., more comfortable sensation, or a sensation that may be correlated with or specific to the specific target nerve fiber(s) within the targeted peripheral nerve. As a non-limiting example, higher frequencies (e.g., 100 Hz or 12 Hz) may evoke sensation(s) or comfortable paresthesia(s) in the region(s) of pain or in alternate target region(s).
While stimulation is being applied, the lead 112 (non-limiting examples of the lead could include a single or multi-contact electrode that is designed for temporary (percutaneous) or long-term (implant) use or a needle electrode (used for in-office testing only), e.g., see
The appropriate electrode spacing from a targeted nerve may depend on various factors, and similar stimulation settings may evoke different responses from different peripheral nerves or from the same nerve but at different locations along the nerve. Differences between patients also evoke different responses, even if the electrode 116 is spaced at similar distances. Thus, electrode spacing from the nerve may be about 10 to about 20 millimeters for one target nerve at a given stimulation intensity while the spacing may be about 20 to about 40 millimeters for a second target nerve at the same stimulation intensity. As the distance between the electrode and the target nerve increases the effects of the stimulation at the target nerve may decrease.
If specific response(s) (e.g., desired response(s) and/or undesired response(s)) may be obtained at a range of intensities that are too low, then the electrode 112 may be located in a non-optimal location (e.g., too close to the target nerve(s)). In such situations, therefore, the clinician may adjust the lead location to change the electrode(s) location(s) until the appropriate responses are achieved from the patient.
The stimulus intensities may be a function of many variables. The stimulus intensities set forth herein are meant to serve as non-limiting examples only, and may need to be scaled accordingly. As a non-limiting example, if electrode shape, geometry, or surface area were to change, then the stimulus intensities may need to change appropriately. For example, if the intensities were calculated for a lead with an electrode surface area of approximately 20 mm2, then the intensities may need to be scaled down accordingly to be used with a lead having an electrode surface area of 0.2 mm2 because a decrease in stimulating surface area may increase the current density, increasing the potential to activate excitable tissue (e.g., target and non-target nerve(s) and/or fiber(s)). Alternatively, if the intensities were calculated for a lead with an electrode surface area of approximately 0.2 mm2, then the intensities may need to be scaled up to be used with a lead with an electrode surface area of 20 mm2. Alternatively, stimulus intensities may need to be scaled to account for variations in electrode shape or geometry (between or among electrodes) to compensate for any resulting variations in current density. In a non-limiting example, the electrode contact surface area may be between approximately 0.1-20 mm2, 0.01-40 mm2, or 0.001-200 mm2. In a further non-limiting example, the electrode contact configuration may include one or more of the following characteristics: cylindrical, conical, spherical, hemispherical, circular, triangular, trapezoidal, raised (or elevated), depressed (or recessed), flat, and/or borders and/or contours that are continuous, intermittent (or interrupted), and/or undulating.
Stimulus intensities may need to be scaled to account for biological factors, including but not limited to patient body size, weight, mass, habitus, age, and/or neurological condition(s). As a non-limiting example, patients that are older, have a higher body-mass index (BMI), and/or neuropathy (e.g., due to diabetes) may need to have stimulus intensities scaled higher (or lower) accordingly.
As mentioned above, if the lead 112 is too far away from the targeted peripheral nerve, then stimulation may be unable to evoke the desired response (e.g., comfortable sensation(s) (or paresthesia(s)), and/or pain relief) in the desired region(s) at the desired stimulus intensity(ies). If the lead 112 is too close to the targeted peripheral nerve, then stimulation may be unable to evoke the desired response(s) (e.g., comfortable sensation(s) (or paresthesia(s)), and/or pain relief) in the desired region(s) at the desired stimulus intensity(ies) without evoking undesirable response(s) (e.g., unwanted and/or painful sensation(s) (or paresthesia(s)), increase in pain, and/or generation of additional pain in related or unrelated area(s)). In some cases, it may be difficult to locate the optimal lead placement (or distance from the targeted peripheral nerve) and/or it may be desirable to increase the range of stimulus intensities that evoke the desired response(s) without evoking the undesired response(s) so alternative stimulus waveforms and/or combinations of leads and/or electrode contacts may be used. In the preferred embodiment, a biphasic, charge-balanced pulse may be generated for tissue stimulation, however, non-limiting examples of alternative stimulus waveforms may include the use of a pre-pulse to increase the excitability of the target fiber(s) and/or decrease the excitability of the non-target fiber(s).
This stimulation may be used pre-operatively or intra-operatively to limit or prevent post-operative pain. Those skilled in the art will recognize that, for simplicity and clarity, the full structure and operation of all devices and processes suitable for use with the present teachings are not being depicted or described herein. The present disclosure contemplates combining the various features described above in any manner and is not limited solely to the combinations described above.
III. Example of a Method of Use
Following a transfemoral (above-knee) lower limb amputation (TFA), the majority of patients experience moderate to severe acute pain, and a lesser number continue to experience moderate to severe subacute pain and chronic pain. Acute and subacute postoperative pain may limit early recovery and rehabilitation. The patients experience different types of pain, including nociceptive, inflammatory, and neuropathic pain. The mid-thigh is innervated by the femoral, lateral femoral cutaneous, obturator, and the sciatic nerves. Anesthetic block of these nerves individually or as a group may reduce acute pain following a TFA. Adequate treatment of acute and subacute pain may also prevent the development of debilitating chronic pain resulting from TFA. Accordingly, electrical stimulation of nerves that innervate, or portions of which innervate, a portion of the body (specifically a limb or joint) to undergo amputation surgery, where such stimulation occurs before, during and/or after amputation surgery, or some combination of those times, may be used to reduce pain and enhance recovery. In this example, if the targeted peripheral nerve includes nerves of the femoral and sciatic nerves and/or their nerve branches, the instruction(s) and method may include:
1) Place the patient in a comfortable and/or appropriate position.
2) Ask the patient to shade their area of pain on a diagram of the body. For example, as shown in
3) Prepare the lead insertion site with antiseptic and local subcutaneous anesthetic (e.g., 2% lidocaine) may be used as well.
4) Locate the site of skin puncture with appropriate landmarks, such as the inguinal crease and femoral artery (for the femoral nerve) and the interior and lateral (ventral) to the midpoint of the line connection greater trochanter and ischial tuberosity (for the sciatic nerve).
5) Insert a sterile percutaneous electrode lead (such as the lead 112 described above) preloaded in the introducer needle (such as that 120 described above) at a predetermined angle based on the landmarks used. The lead 112 may be of any appropriate configuration, such as by way of a non-limiting example, a single fine wire with one lead to target each nerve.
6) Place a surface stimulation return electrode in proximity to the lead insertion site (
7) Couple the lead 112 to the external pulse generator or external electrical stimulation device 102 and to the return electrode. Set the desired stimulation parameters on the external pulse generator or external electrical stimulation device 102, or through a controller. Test stimulation may be delivered using a current-regulated pulse generator, for example. The external pulse generator may be a battery-powered stimulator, for example.
8) Advance the introducer needle 120 slowly until the subject reports the first evoked sensation in the region experiencing pain. Progressively reduce the stimulus amplitude and advance the introducer needle 120 more slowly until the sensation can be evoked in the painful region at predetermined stimulus amplitude (e.g., 1 mA). Stop the advancement of the introducer needle 120, and increase the stimulus amplitude in small increments (e.g., 0.1 mA) until the stimulation-evoked tingling sensation (paresthesia) expands to overlay the entire region of pain. The electrode 116 may be located at an area to generate maximum paresthesia coverage of the region of pain, as defined by a patient shaded diagram of the body. During stimulation, the patient is asked to estimate how much of the area of pain is covered by paresthesia. For example, as in
9) Withdraw the introducer needle 120, leaving the percutaneous lead 112 in proximity but away from the target nerve. Further, a plurality of leads may be placed percutaneously near or approximately adjacent to the nerves innervating the regions of pain, and stimulation may be applied to determine optimal stimulus parameters and lead locations. Although in some embodiments, only a single lead 112 may be utilized.
10) Cover the percutaneous exit site and lead 112 with a bandage (
11) The external pulse generator or external electrical stimulation device 102 may be programmed to 100 Hz, 15 μs with amplitude sufficient to generate maximum paresthesia coverage. The parameter may include 100% duty cycle (for both femoral and sciatic) for 24 hours per day. The stimulation may be on for the duration of the acute or subacute pain of the patient. Patients may receive the stimulation therapy for a predetermined time, such as, by way of a non-limiting example, two to four weeks or 28-30 days or 56-60 days.
12) The stimulation intensity may need to be increased slightly during the process due to causes such as habituation or the subject becoming accustomed to sensation. However, the need for increased intensity may be unlikely and usually only occurs after several days to weeks to months as the tissue encapsulates and the subject accommodates to stimulation. It is to be appreciated that the need for increased intensity may happen at any time, which may be due to either lead migration or habituation, but may also be due reasons ranging from nerve damage to plasticity/reorganization in the central nervous system.
13) Prior to insertion of the lead 112 and introducer needle 120, a sterile test needle may be used to deliver stimulation and determine the desired site of insertion.
14) If paresthesia cannot be evoked with the initial lead placement, the introducer needle 120 may be redirected.
15) If stimulation fails to elicit paresthesia in a sufficient region (e.g., >50%) of pain, then a second percutaneous lead may be placed to stimulate the nerves that are not activated by the first lead, i.e., the nerves innervating the region of post-operative pain.
Percutaneous electrical stimulation of nerves innervating the mid-thigh as discussed in the example above may be used to generate paresthesia to provide pain relief for any type of post-op pain following an amputation surgery (e.g., immediate acute phase=0 to 3-5 days; post-acute or subacute phase=3-5 days to 30 days), and/or to prevent the later development of chronic pain. In this approach, one might use the femoral and sciatic nerves, or they may also stimulate the lumbar plexus to target the femoral, obturator, and/or lateral femoral cutaneous nerves. Additionally, there may be an anterior approach as well as a posterior approach to targeting these nerves.
An alternative embodiment may include using a needle electrode/lead and placing it during insertion of needles used during anesthetic peripheral nerve block. Additionally, in a different embodiment the pulse trains may be varied, as varied pulse shapes may improve selectivity of activation of paresthesia fibers versus pain fibers. Percutaneous electrical stimulation of nerves may provide some pain relief as anesthetic block without many of its drawbacks. This therapy may be provided as a temporary therapy or as a permanent implant. Acute pain relief may allow patients to recover sufficiently enabling them to begin rehabilitation. It is generally thought that if 50% paresthesia coverage is achieved, then there is a 70% success rate. Oftentimes after the stimulation therapy, the pain will never return to the patient.
The TFA is discussed herein for the sake of brevity. It, however, is to be understood that the systems and methods may be employed to condition a body before or after any surgical amputation of an extremity, tissue or limb. While stimulation of the femoral and/or sciatic nerves should generally provide relief of pain following an amputation surgery of the leg, more distal peripheral nerves may be targets for amputations related to distal portions of the leg (toe, foot, ankle, e.g.). For arm/hand limb amputation-related pain, nerves near the brachial plexus, near or below the shoulder, elbow, or wrist may be targeted.
In peripheral nerve stimulation, the lead 112 may be placed such that the electrode is in a tissue by which the targeted nerve passes, but stimulation actually relieves pain that is felt distal (downstream) from where the lead 112 is placed. In peripheral nerve stimulation, the lead 112 may be placed in a tissue such that the electrode is conveniently located near a nerve trunk that passes by the lead 112 on the way to or from the painful area. The key is that the lead 112 may be placed in a tissue that is not the target (painful) tissue, but rather a tissue that is located away from the painful region, which is a safer and more convenient location to place the lead 112.
Peripheral nerve stimulation may provide stimulation-generated paresthesia (that ideally overlap with the area of pain) but may not require evoking a muscle contraction to place the lead 112 correctly such that the electrode 116 on the lead 112 is in a preferred location to stimulate the targeted peripheral nerve. The target regions in which pain is felt and which are targeted for generation of paresthesia may not be the same region in which the lead 112 is placed.
Imaging (e.g., ultrasound or an alternate imaging technique, e.g., fluoroscopy) may be used to improve lead 112 placement to ideally locate the electrode near a targeted peripheral nerve. Ultrasound may improve lead 112 placement in the form of increasing the total speed of the procedure. Specifically, ultrasound may shorten the procedure's duration by locating the lead 112 in a more optimal location. Doing so may: improve recruitment of the target fibers in the target nerve and minimize recruitment of non-target fibers in either the target nerve and/or in non-target nerve(s); and minimize risk and/or damage to the patient during placement of the lead by avoiding blood vessels, organs, bones, ligaments, tendons, lymphatic vessels, &/or other structures that may be damaged. One reason that imaging may be useful is that some peripheral nerves are (but do not have to be) located relatively deeply. Alternatively, fluoroscopy may be desirably avoided, thus lessening the cost of the procedure and the risk of radiation exposure.
In the present system and method, the patient may not need to give verbal, written, or other type of feedback or indication of what they feel as the lead is being advanced towards the peripheral nerve if imaging is used to guide lead placement. In addition, any known method for non-verbal communication can be used, including those used by anesthesiologists. This allows the system to be placed in an unconscious patient, e.g., in a sedated patient or intra-operatively. However, patient feedback during lead 112 advancement may improve lead placement in some patients. The patient may indicate sensations during tuning of stimulus intensity. As non-limiting examples, those sensations reported by the patient may include first sensation (minimum stimulus intensity that evokes a sensation), level of comfort, maximum tolerable sensation, pain, and qualities or descriptions of the sensations. Alternatively, if the system is used preoperatively, as there will not be any patient feedback of post-operative pain to guide the paresthesia coverage, the optimal coverage would be a region that is likely to be painful following the amputation surgery (e.g., in the case of a TFA, both the front and back of the mid-thigh).
The region in which the patient perceives stimulation-induced sensations or paresthesia may be an important indicator of the potential success of the therapy. This may help screen potential candidates and may help determine the appropriate stimulation parameters (including but not limited to lead location). Further, such parameters may be adjusted so that the region in which paresthesia is perceived overlaps with the region of pain. For example, the intensity of the electrical stimulation may be increased by increasing the amplitude or pulse duration of the stimulation waveform, thereby activating more targeted fibers in the peripheral nerve and increasing the area or location(s) in which paresthesia is felt until the area includes or overlaps with the region of pain.
As an alternative to using perception of stimulation induced sensations and/or paresthesia, the level of pain or change in the intensity of pain during or due to stimulation may be used to adjust stimulation parameters (including but not limited to lead location). For example, if a patient is experiencing “very high” pain before stimulation, and no sensory or motor responses are evoked during stimulation, if the pain decreases to “low”, the system would be considered satisfactory in the patient.
Stimulation may be delivered so as to provide pain relief without evoking additional sensations or paresthesia. Stimulation may be delivered using sub-threshold (i.e., below the threshold for sensation or perception) or other parameters that provide relief of pain without producing sensations or paresthesia. As a non-limiting example, stimulation may be delivered to evoke a response, such as sensation, paresthesia, motor or muscle response, to guide, confirm, improve, or optimize lead or electrode placement and stimulation parameters, and following placement of the lead(s) and/or electrode(s) stimulation parameters may then be set to provide pain relief without unwanted responses (which may include sensations, paresthesia, motor or muscle activation or contractions). Alternatively, in some scenarios responses such as sensations, paresthesia, and/or muscle activation or contractions may be desirable and/or beneficial and may be produced intentionally as part of, in combination with, and/or simultaneously with the therapy.
Although the embodiments of the present invention have been illustrated in the accompanying drawings and described in the foregoing detailed description, it is to be understood that the present teachings are not to be limited to just the embodiments disclosed, but that the invention described herein is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the claims hereafter. The claims as follows are intended to include all modifications and alterations insofar as they come within the scope of the claims or the equivalent thereof.
The terms “component,” “module,” “system,” “interface,” “platform,” “service,” “framework,” “connector,” “controller,” or the like are generally intended to refer to a computer-related entity. Such terms may refer to at least one of hardware, software, or software in execution. For example, a component may include a computer-process running on a processor, a processor, a device, a process, a computer thread, or the likes. In another aspect, such terms may include both an application running on a processor and a processor. Moreover, such terms may be localized to one computer and/or may be distributed across multiple computers.
What has been described above includes examples of the present specification. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the present specification, but one of ordinary skill in the art may recognize that many further combinations and permutations of the present specification are possible. Each of the components described above may be combined or added together in any permutation to define the present system and method. Accordingly, the present specification is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.
This application claims priority to, and all benefit, from U.S. Provisional Patent Application No. 62/589,043 filed on Nov. 21, 2017, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62589043 | Nov 2017 | US |
