Patent ID: 12257441

DETAILED DESCRIPTION

Embodiments of implantable medical devices described herein may be useful for numerous types of neurostimulation therapies, such as for pain control, autonomic nervous system modulation, functional electrical stimulation, tremor, and more. Embodiments of implantable medical devices described herein may be useful for stimulating one or more nerves to control symptoms of overactive bladder, urgency frequency, nocturia, painful bladder syndrome, chronic pelvic pain, incontinence, or other pelvic health conditions. These embodiments may also be useful for stimulating one or more peripheral nerves to control pain in one or more areas of the body, such as a foot, ankle, leg, groin, shoulder, arm, wrist, or the back, for example. In one example, embodiments of implantable medical devices described herein may be used to stimulate a tibial nerve of a patient.

Referring now toFIGS.3A-3C, an IMD100is depicted. IMD100generally includes a housing102, and a lead120. Housing102includes electronic circuitry and associated components therein, e.g., comprising one or more electronic circuits for delivering electrical stimulation therapy. Housing102can also include communication circuitry disposed therein for receiving programming communication from an external programmer, or providing feedback to a programmer or other external device.

In one example, housing102can include an energy source enclosed therein, e.g., a battery. In another example, IMD100can be configured to receive energy signals from an external device and transduce the received energy signals into electrical power that is used to recharge a battery of IMD100. In one example, IMD100may be configured to receive energy signals from an external device and transduce the received energy signals into electrical power that is used to power the device to deliver electrical stimulation therapy.

IMD100can include one or more fixation elements or anchor features104such as suture tabs or apertures, tines, barbs, or other suitable passive or active fixation elements. As depicted inFIGS.3A-3C, housing102of IMD100includes an aperture104configured to facilitate securing housing102to a patient by the use of a suture, clip, or other surgical fastening tools. Housing102can also include a shoulder or flange portion106.

Lead120can include one or more electrodes122arranged thereon. As depicted inFIGS.3A-3C, electrodes122are approximately equally spaced along a length of lead120. However, alternate arrangements are within the scope of the invention, such as a greater or lesser number of electrodes, unequal spacing of electrodes, and different types of electrodes. Suitable electrode types can include ring electrodes, tip electrodes, coil electrodes, and others. Lead120can be referred to as a stubby lead, or pigtail lead.

Lead120can be flexible, semi-rigid, or rigid. In an example, lead120can be removably coupled to housing102. In other examples, lead120can be non-removably coupled to or integrally formed with housing102. The connection between lead120and housing102can include a flexible joint or hinge. Although not depicted in the Figures, lead120can include one or more fixation elements or features such as tines, barbs, suture tabs, or other suitable passive or active fixation elements as known in the art.

Referring now toFIGS.1-3C, a method of implanting IMD100proximate a tibial nerve will be described. On an ankle50of a patient, a first incision52in skin54is made. First incision52can be a one to five cm axial incision superior and posterior to a medial malleolus and above a tibial nerve60on a medial aspect of ankle50. In another example, first incision52can be in a range of one to three cm long. With first incision52made, a medical practitioner can dissect down through fat layers56to fascia58. With fascia58exposed, a second incision or nick70is made in fascia58at an inferior end (toward a heel of the patient) of the dissected area. In an example, second incision70is smaller than first incision52.

In an example, the size of second incision70is chosen to allow lead120of IMD100to pass therethrough but not allow housing102to pass therethrough. In an example, second incision70and lead120can be appropriately sized to provide a friction fit therewith. In an example, second incision70can be sized such that passage of lead120through second incision70causes stretching of second incision70to accommodate lead120. In an example, IMD100may include a shoulder portion106sized and shaped to prevent passage of housing102through second incision70. In another example, housing102may itself be sized and shaped larger than lead120to prevent passage of housing102through second incision70.

Lead120may then be inserted through second incision70inward toward tibial nerve60and inferiorly toward the heel, as depicted inFIG.3B. Prior to anchoring housing102, optional testing of IMD100may be performed to determine if lead120has been properly positioned close to tibial nerve60to elicit a desired response from an applied electrical stimulation. In an example, IMD100is controlled by an external programmer to deliver test stimulation, and one or more indicative responses are monitored, such as toe flexion from simulation of the tibial motor neurons controlling the flexor hallucis brevis or flexor digitorum brevis, or a tingling sensation in the heel or sole of the foot excluding the medial arch. If such testing does not elicit appropriate motor or sensory responses, the practitioner should withdraw and reposition lead120and retest.

In an example, proper positioning of lead120is achieved with electrodes122inward of fascia58and in close proximity to tibial nerve60, wherein tibial nerve60is commonly located about one to six millimeters deep to fascia58in the region of ankle50which is superior to the medial malleolus.

Once a practitioner has determined lead120is properly positioned to provide an appropriate patient response to delivered stimulation therapy, housing102can be secured in place such as inFIG.3C. In an example, a suture or similar surgical fastening means can be attached between anchor feature104of housing102and surrounding tissue of the patient. Thus IMD100is therefore fixed in position at two points, with housing102secured by way of anchor feature104and lead120secured at second incision70. In another example, housing102is not anchored with any surgical fastening means, and retention of housing102can be accomplished by an interference fit against tissue in and around the implant site. First incision52can then be closed by appropriate means.

Referring now toFIGS.4A-4C, a tool150can be utilized during the implant procedure. Tool150includes a body or handle152suitable for being grasped by a practitioner, and a first end154and a second end156. First end154can include a shaft portion160which terminates in a rounded or blunt tip162, and a port164defined in tip162. In an example, shaft portion160can have a diameter less than a diameter of body152. In another example, shaft portion160can have a diameter approximately similar to a diameter of lead120. In an example depicted inFIG.4Ashaft portion160can be generally straight and aligned with handle152. In another example depicted inFIG.4B, shaft portion160can have a curved profile.

Second end156of tool150can include an actuator168. In another example, actuator168can be located along body152. Actuator168is operably coupled to a movable piercing element172disposed within tool150. Referring toFIG.4C, piercing element172is movable by way of actuator168between a retracted position (top) wherein piercing element172is contained within tool150, and a deployed position (bottom) wherein a tip of piercing element172protrudes from port164. Piercing element172can be sized and shaped to easily create a second incision70appropriately sized for passage of lead120therethrough. In another example, piercing element172may be a conventional guidewire, manually manipulated through a passageway within tool150and exiting through port164.

In an example, tool150is configured such that the default position of piercing element172is in the retracted position, and moving piercing element172to the deployed position locks piercing element172in the deployed position. A release mechanism176can be included in tool150to release piercing element172from the deployed position and return piercing element172to the retracted position.

In operation, tool150can be used by a practitioner to dissect tissue at the implant site and create a predictably sized second incision70in fascia58. After first incision52is created, and the fascia is exposed, a practitioner can operate the actuator168of the tool150to move piercing element172from the retracted position to the deployed position. A practitioner can then utilize tool150with piercing element172in the deployed position to create second incision70at a desired location in fascia58. A practitioner can then operate actuator176to move the piercing element172from a deployed to a retracted position as the shaft of the tool160is advanced through the second incision70. With the piercing element172retracted the shaft of the tool160can be used to bluntly dissect a path for the lead120through the tissues below the fascia with minimal risk of piercing or rupturing a blood vessel or tendon sheath. Positioning and securing lead120and housing102can then be accomplished as described above.

Referring now toFIGS.5A and5B, an IMD200is depicted as another example of the present disclosure. IMD200is configured for implantation using a guidewire, and IMD200generally includes a housing202, a lead220, and a guidewire passageway240. The embodiments of IMD200have many similarities to the embodiments of IMD100described above and for simplicity the description of all common components is not repeated in the following, and like numerals may designate like parts throughout that are corresponding or analogous.

IMD200can include one or more fixation elements or anchor features such as suture tabs or apertures, tines, barbs, or other suitable passive or active fixation elements. As depicted inFIG.5A, housing202includes a plurality of passive fixation elements in the form of protrusions206disposed on housing202. Although not depicted in the Figures, IMD200can include additional fixation or anchoring elements, such as a tab or loop configured to facilitate securing housing202to a patient by the use of a suture, clip, or other surgical fastening tools.

Lead220can include one or more electrodes222arranged thereon. As depicted inFIG.5A, lead220includes one electrode222disposed near a tip of lead220. In the embodiment ofFIG.5B, lead220includes a plurality of electrodes222which are approximately equally spaced along a length of lead220. However, alternate arrangements are within the scope of the invention, such as a greater or lesser number of electrodes, unequal spacing of electrodes, and different types of electrodes. Suitable electrode types can include ring electrodes, tip electrodes, coil electrodes, and others. Lead220can be referred to as a stubby lead, or pigtail lead.

As depicted inFIGS.5A-5B, IMD200includes a structure226for coupling lead220to housing202. Structure226can be configured to create a desired alignment or orientation of lead220with respect to housing202. Further, a longitudinal axis of lead220is oriented generally parallel with a longitudinal axis of housing202, although other configurations are possible. Structure226can be flexible, semi-rigid, or rigid. Similarly, lead220can be flexible, semi-rigid, or rigid. In an example, lead220can be removably coupled to housing202. In other examples, lead220can be non-removably coupled to or integrally formed with housing202. The connection between lead220and housing202can include a flexible joint or hinge. Although not depicted in the Figures, lead220can include one or more fixation elements or features such as tines, barbs, suture tabs, or other suitable passive or active fixation elements as known in the art.

IMD200is configured for implantation over a guidewire, and IMD200includes a guidewire passageway240which can be included as part of, or coupled with, housing202, lead220, structure226, or a combination thereof. As depicted inFIG.5Afor example, guidewire passageway240extends through lead220.

In an example, a tool250as depicted inFIGS.6A-6Bcan be utilized to implant IMD200within a patient. Tool250includes an outer elongated sheath252having a handle254, and an inner sheath260releasably and slidingly engageable with outer sheath252. Inner sheath260includes a cradle262configured to selectively carry IMD200or a portion thereof.

Referring now toFIGS.7A-7C, a method of implanting IMD200proximate a tibial nerve will be described. On an ankle50of a patient, a first incision52in skin54is made. First incision52can be a one to three cm vertical incision superior and posterior to a medial malleolus and above a tibial nerve60on a medial aspect of ankle50. With first incision52made, a medical practitioner can dissect down through fat layers56to fascia58as needed.

In an example, with fascia58exposed, a small second incision or nick70is made in fascia58at an inferior end (toward a heel of the patient) of the dissected area using a scalpel or similar device. In another example, a guidewire280can be inserted directly through fascia58, and advanced downward (towards the heel) and inward on a path that is parallel to a tibia and tibial nerve60. In an example, guidewire280is inserted at a point towards a superior end (closest to the knee) of first incision52. Proper insertion depth and trajectory of guidewire280may be determined in a number of ways, including referencing anatomical landmarks such as the tibia or Achilles tendon, or utilizing ultrasound imaging, or by connecting guidewire280to an external pulse generator and observing sensory or motor responses of the patient to test stimulation.

With guidewire280appropriately positioned, IMD200can be loaded in cradle262of tool250, as depicted inFIG.6A. In an example, IMD200may be provided loaded in cradle262, such as part of a kit. Tool250and IMD200are then advanced onto guidewire280such that guidewire280is disposed within guidewire passageway240of IMD200. Tool250and IMD200are further advanced along guidewire280to the implant site until lead220is proximate fascia58. A practitioner can then grasp inner sheath260of tool250and advance outer sheath252towards fascia58, thereby inserting lead220through fascia58along guidewire280such that lead220is below fascia58while housing202remains outside of fascia58, such as depicted inFIGS.7B and7C.

Optional testing of IMD200may be performed to determine if lead220has been properly positioned close to tibial nerve60to elicit a desired response from an applied electrical stimulation. In an example, IMD200is controlled by an external programmer to deliver test stimulation, and one or more indicative responses are monitored, such as toe flexion from simulation of the tibial motor neurons controlling the flexor hallucis brevis or flexor digitorum brevis, or a tingling sensation in the heel or sole of the foot excluding the medial arch. If such testing does not elicit appropriate motor or sensory responses, the practitioner should withdraw and reposition lead220and retest.

Once a practitioner has determined lead220is properly positioned to provide an appropriate patient response to delivered stimulation therapy, housing202can be secured in place. In an example, a suture or similar surgical fastening means can be attached between an anchor feature of housing202and surrounding tissue of the patient. Thus IMD200is therefore fixed in position at two points, with housing202secured by way of an anchor feature and lead220secured by an interference fit through fascia58. First incision52can then be closed by appropriate means.

An advantage of the devices and methods described herein can be improved patient safety and satisfaction after implant. By making first incision52superior to medial malleolus and directing the lead down toward the heel instead of up toward the knee allows for faster and safer tissue healing. Body tissues higher up on the ankle are thicker and heal faster than tissues lower down, and the wearing of shoes by the patient will be less likely to interfere with a wound site superior to the medial malleolus than lower down at the level of the medial malleolus.

Referring now toFIG.8, depicted are alternate form factors for an IMD as described and disclosed herein.

In one example, an IMD and implant tool are provided together as part of a kit. In another example, a kit may include instructions for implanting, programming or operating the system, the instructions being recorded on a tangible medium or including indications linking a user to electronically accessible instructions.

It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include non-transitory computer-readable media, which corresponds to a tangible medium such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor” as used herein may refer to any of the foregoing structure or any other physical structure suitable for implementation of the described techniques. Also, the techniques could be fully implemented in one or more circuits or logic elements.