HK1172575B - Nerve cuff with pocket for leadless stimulator - Google Patents

Abstract

An extravascular nerve cuff that is configured to hold a leadless, integral, implantable microstimulator. The nerve cuff may include a cuff body having a pocket or pouch for removably receiving the implantable device within. The nerve cuff can be secured around the nerve such that the electrodes of the device are stably positioned relative to the nerve. Furthermore, the nerve cuff drives the majority of the current from the stimulation device into the nerve, while shielding surrounding tissues from unwanted stimulation.

Description

Nerve cuff with pocket for leadless stimulator

Cross Reference to Related Applications

The present application claims the benefit of U.S. provisional patent application No. 61/185,494 entitled "nerve cuff with pocket for leadless stimulator" filed on 9.6.2009 from 35 u.s.c.119.

Incorporation by reference

All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

Technical Field

The present invention relates generally to implantable neural stimulators, and more particularly to a nerve cuff with a pocket for removably receiving an active leadless stimulation device, and a method of stimulating a nerve using such a nerve cuff.

Background

A variety of implantable electrical stimulation devices have been developed for the therapeutic treatment of a variety of diseases and disorders. For example, implantable cardioverter-defibrillators (ICDs) have been used to treat various cardiac conditions. Spinal Cord Stimulators (SCS) or Dorsal Column Stimulators (DCS) have been used to treat chronic pain disorders, including back surgery failure syndrome, complex regional pain syndrome, and peripheral neuropathy. The Peripheral Nerve Stimulation (PNS) system has been used to treat chronic pain syndrome and other diseases and disorders. Functional Electrical Stimulation (FES) systems have been used to restore partial function to the distal ends of spinal cord injured patients who are paralyzed without treatment.

A typical implantable electrical stimulation system may include a system having one or more programmable electrodes on a lead that are connected to an Implantable Pulse Generator (IPG) that contains a power source and stimulation circuitry. However, these systems can be difficult and/or time consuming to implant because the electrodes and IPG are typically implanted in separate areas, and thus leads must be passed through the body tissue to connect the electrodes and IPG. Furthermore, since the wires are typically thin and long, they are also susceptible to mechanical damage over time.

Recently, in order to solve the above disadvantages, a small-sized implantable neurostimulator technology, i.e., a microstimulator, having an integrated electrode connected to a stimulator body has been developed. This technique allows the typical IPG, lead and electrode described above to be replaced with a single device. Several advantages of removing the wire include: surgical time is reduced by eliminating the need to implant the electrodes and IPG in different places, the need for a device pocket, access to the electrode site, and strain relief affixed to the lead itself, for example. Reliability is thus significantly increased, particularly in soft tissues and across joints, because the active components (e.g., wires) are now part of a rigid structure and are not subject to mechanical damage due to repeated bending or flexing over time.

However, leadless integrated devices tend to be larger and heavier than electrode/lead assemblies, making it difficult to stabilize the device in a proper position relative to the nerve. Without device stability, the nerve and/or surrounding muscles or tissue may be damaged by movement of the components.

Thus, there remains a need for a leadless integrated device that is stably positioned on a nerve and that enables the stimulation device to be easily removed and/or replaced.

Disclosure of Invention

Described herein are extravascular nerve cuffs for securing a leadless, integrated implantable device to a nerve. The nerve cuff comprises in particular a bag or a pocket. The cuff electrode configuration of the stimulation device allows the device to be stably positioned adjacent to a nerve, such as the vagus nerve. In addition, the cuff electrode configuration also has the property of driving most of the current into the nerve while protecting surrounding tissue from unwanted stimulation. Methods of fastening leadless microstimulators using such nerve cuffs and methods of stimulation using microstimulators secured by such cuffs are also described herein.

The use of a leadless envelope with a microstimulator has many advantages, including reduced encapsulation (e.g., about 100 microns) relative to a system without a leadless envelope, because there is less "pull" on the leadless envelope. In addition, a leadless cuff that can be reliably attached to the nerve and hold the microstimulator in place can allow the microstimulator to be calibrated or replaced while remaining equally positioned relative to the nerve.

In one embodiment of the invention, the nerve cuff generally comprises a cuff body or stent made of a flexible material, such as a pharmaceutical grade soft polymer material (e.g., Silastic)^TMOr Tecothane^TM) A formed envelope or sleeve having a pocket or pouch defined therein for removably receiving the leadless stimulation device. A leadless stimulation device is positioned in the pocket or sleeve such that the electrodes of the device are positioned proximate to the nerve to be stimulated. The pocket may be defined by a space between the stimulation device and the interior surface of the cuff body, or may comprise a pocket structure attached to the cuff body for receiving the stimulation device. The nerve cuff may be coupled to the nerve, a peripheral sheath containing the nerve, or both according to a desired level of stability.

The nerve cuff may be implanted in the following manner. The method includes the steps of first dissecting a nerve, such as a vagus nerve, from a peripheral sheath of the nerve, wrapping the nerve with a nerve cuff, coupling or suturing the nerve cuff to either the nerve or the sheath, and inserting a stimulation device into a pocket or pouch in the cuff body, thereby bringing the stimulation device into proximity with the nerve.

For example, described herein are nerve cuffs for ensuring stable communication of a leadless microstimulator with a nerve. The nerve cuff may include: a cuff body having a channel extending within a length of the cuff body for passage of a nerve; a pocket inside the cuff body, the pocket configured to removably retain a leadless microstimulator; and an elongated open slit extending along the length of the cuff body, the slit configured to open to provide access to the pouch.

The nerve cuff may also include internal electrical contacts within the cuff body. For example, the internal electrical contacts may be configured to electrically couple the microstimulator and the nerve. In some variations, the nerve cuff further comprises an external electrical contact on an outer surface of the cuff body, the external electrical contact configured to couple with a microstimulator.

In some variations, the cuff body includes a shield configured to electrically isolate the microstimulator within the nerve cuff. The cuff body may have a uniform thickness or may have a non-uniform thickness. For example, the envelope body may have a thickness of between about 5 mils (mil) and about 20 mils.

In some variations, the outer surface of the nerve cuff is substantially smooth and atraumatic. The nerve outer surface of the nerve cuff may be rounded and/or compliant. For example, the body may conform to the area of the body of the implanted cuff and/or microstimulator.

In some variations, the channel comprises a support channel configured to support a nerve therein to prevent compression of the nerve.

The elongated open slit may extend along the length of the cuff body in an interconnected pattern. In some variations, the slit extends along a side of the cuff body proximate to the channel. In other variations, the slit extends along the top of the cuff body, opposite the channel.

The nerve cuff may also include one or more attachment sites configured in the elongated open slit to help ensure the slit closes. For example, the attachment site may be a hole or a passage for a suture.

In some variations, the envelope body is formed from a flexible and biocompatible polymer, for example a polymeric biocompatible material, such as a silicone polymer.

Also described herein is a nerve cuff for ensuring stable communication of a leadless microstimulator with a nerve, the nerve cuff comprising: an insulating cuff body having a nerve channel extending within a length of the cuff body for passage of a nerve, wherein the cuff body electrically insulates the microstimulator within the cuff body; a conductive surface within the neural channel, the guide surface configured to engage one or more electrical contacts on the microstimulator; a pocket inside the cuff body, the pocket configured to removably retain a leadless microstimulator; and an elongated open slit extending along the length of the cuff body, the slit configured to open to provide access to the pouch.

As mentioned above, the nerve cuff may include one or more external electrical contacts on an outer surface of the cuff body configured for coupling with a microstimulator.

In some variations, the nerve cuff body has a uniform thickness. In other variations, the nerve cuff body has a non-uniform thickness. The envelope body may have a thickness of between about 5 mils and about 20 mils.

The outer surface of the nerve cuff may be substantially smooth and atraumatic. For example, the outer surface of the nerve cuff may be contour-matched.

In some variations, the channel through the nerve cuff comprises a support channel configured to support a nerve therein to prevent compression of the nerve.

In some variations, the elongated open slit extends along the length of the cuff body in an interconnected pattern. For example, the pattern of interconnects may be a zigzag pattern or a sinusoidal pattern.

Also described herein is a method of implanting a leadless microstimulator in communication with a vagus nerve, the method comprising: exposing the vagus nerve; opening a slit of a nerve cuff having a nerve cuff body, wherein the slit opens along a length of the nerve cuff body; placing the nerve cuff around the vagus nerve such that the nerve is located within a channel extending the length of the nerve cuff; inserting a leadless microstimulator into a pocket of the nerve cuff; and ensuring that the slit of the nerve cuff is closed such that the leadless microstimulator is in electrical communication with the nerve and is electrically insulated within the nerve cuff body.

In some variations, the step of securing the opening slit of the nerve cuff closed comprises securing the slit such that the leadless microstimulator engages an internal electrical contact within the nerve cuff body. The leadless microstimulator may engage an internal electrical contact configured to provide circumferential stimulation around a nerve within the channel.

The securing step may include sewing the seam closed. In some variations the gap may be self-sealing. For example, there is sufficient tension in the envelope to keep it closed by itself. In some variations, dissolvable sutures may be used to hold the closure until the body encloses the aperture.

The method may further include the step of testing the microstimulator to confirm electrical communication with the nerve.

In some variations, the step of placing the nerve cuff includes placing an oversized nerve cuff around the vagus nerve.

Also described herein is a method of implanting a leadless microstimulator in communication with the vagus nerve, the method comprising the steps of: exposing the vagus nerve; opening a slit of a nerve cuff having a nerve cuff body, wherein the slit opens along a length of the nerve cuff body; placing the nerve cuff around the vagus nerve such that the nerve is located within a channel extending the length of the nerve cuff; inserting a leadless microstimulator into a pocket of the nerve cuff, thereby placing the microstimulator in communication with one or more internal electrical contacts within the nerve cuff; and closing the slit of the nerve cuff, thereby allowing the nerve to communicate with one or more internal electrical contacts.

In some variations, the leadless microstimulator and the internal electrical contact are configured to provide circumferential stimulation around a nerve within the channel. The step of closing may include ensuring that the slit of the nerve cuff is closed. For example, the step of closing may comprise suturing the slit closed. The step of placing the nerve cuff may include placing an oversized nerve cuff around the vagus nerve.

The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the description that follow more particularly exemplify these embodiments.

Drawings

FIG. 1 illustrates, in perspective view, a nerve cuff with a stimulation device implanted proximate a nerve, according to an embodiment of the present invention;

FIG. 1A shows an implanted nerve cuff with the stimulation device of FIG. 1 in a top view;

figure 1B illustrates an implanted nerve cuff with a stimulation device in accordance with an alternative embodiment of the present invention in a top view;

FIG. 2 illustrates an implanted nerve cuff with a strain relief in accordance with an embodiment of the present invention in a front view;

FIG. 3 illustrates an implanted nerve cuff with suture holes in a front view according to one embodiment of the present invention;

FIG. 4 shows the nerve cuff with the suture holes of FIG. 3 in an open view;

figure 5 shows a closure device for the implanted nerve cuff of figure 1 in a top view;

figure 6 shows in perspective a pouch suture of the stimulation device in the pouch of the nerve cuff of figure 1;

figure 7A illustrates a nerve cuff having a compliant protective cover in accordance with one embodiment of the present invention in a top view;

figure 7B shows the nerve cuff of figure 7A in a front view;

figure 8A illustrates an opened nerve cuff in a top view according to one embodiment of the present invention;

figure 8B shows the nerve cuff of figure 8A in a front view; and

figure 8C shows the nerve cuff of figure 8 in a top view, in a closed configuration;

figures 9A and 9B show a cross-section of the envelope body wall in side view, showing a uniform thickness and a varying thickness, respectively;

figures 10A-10D illustrate a variation of a nerve cuff as described herein. FIG. 10A shows an end view, FIG. 10B is a side perspective view, FIG. 10C is a side view, and FIG. 10D is a longitudinal cross-section through a device connected to a nerve showing internal features including a microstimulator;

figures 11A-11D illustrate another variation of the nerve cuff. FIG. 11A shows an end view, FIG. 11B is a side perspective view, FIG. 11C is a side view, and FIG. 11D is a longitudinal cross-section through a device connected to a nerve showing internal features including microstimulators;

FIG. 12 illustrates a variation of a microstimulator that may be used in the nerve cuff described herein;

fig. 13A illustrates a perspective view of another variation of a microstimulator that may be used as described herein. Fig. 13B and 13C are end and bottom views, respectively, of the microstimulator shown in fig. 13A;

figures 14A and 14B show side and end views, respectively, of another variation of a nerve cuff;

figures 15A-15C show a top view, a side view, and a cross-sectional view, respectively, of a nerve cuff as shown in figure 14A connected to a nerve. FIG. 15D is a cross-section through the center of a nerve cuff having a microstimulator secured thereto;

fig. 16 is an internal end view of a microstimulator similar to that shown in fig. 14A-15D;

figure 17 shows the inside of another variation of the nerve cuff in a cross-sectional view;

figure 18 shows the open-top nerve cuff shown in figure 17 in a side perspective view;

figure 19 shows the open-sided nerve cuff in a side perspective view;

figure 20 is a transparent view of the bottom of the nerve cuff showing the nerve channel;

figure 21 shows another variation of a nerve cuff in a side view;

figures 22A-22H illustrate steps of embedding a nerve cuff like that described herein;

figure 23 shows an equivalent circuit that simulates current loss when the nerve cuff is only loosely placed on the nerve.

While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. 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 as defined by the appended claims.

Detailed Description

Embodiments of the present invention relate to a holding device, such as a stent or cuff, that positions the active contacts (i.e., electrodes) of a stimulation device against a target nerve, directing current from the electrodes into the nerve. The retention device also inhibits or prevents the flow of electrical current into the surrounding tissue.

Referring to fig. 1, a nerve cuff 100 suitable for use as an example of a fixed stimulation device is coupled to a nerve 102. The nerve 102 may include any nerve in the human body targeted for therapeutic treatment, such as the vagus nerve. Nerve cuff adapter 100 generally includes an outer stent or cuff body 104, which may comprise any pharmaceutical grade material, such as Silatic^TMBranded silicone elastomers, or Tecothane^TMThe polymer of (1).

In general, the nerve cuff includes a cuff body 104 having (or forming) a pocket or pouch 106 for removably receiving an active implantable stimulation device 108, the implantable stimulation device 108 having one or more integrated leadless electrodes 110 on a surface of the stimulation device 108 proximate the nerve 102. As shown in fig. 1 and 1A, the nerve cuff 100 wraps around the nerve 102 such that the electrodes 110 are positioned proximate to the nerve 102.

The contact or electrode 110 may be positioned directly against the nerve 102 (as depicted in fig. 1A) or in close proximity to the nerve 102 (as depicted in fig. 1B). Referring particularly to fig. 1B, the close proximity of the electrodes 110 and the nerve 102 leaves a gap or space 112 that can be naturally filled with fluid or connective tissue. In one embodiment of the present invention, the electrodes 110 and/or the inner surface of the cuff body 104 may include any steroid coating to help reduce local inflammatory responses and the formation of high impedance tissue.

In one embodiment, the pocket 106 for receiving the stimulation device 108 is defined by an open space between the nerve 102 and the inner surface of the cuff body 104. The stimulation device 108 may be passively held within the pocket 106 by the cuff body 104 or may be actively held on the cuff body by fastening means (e.g., stitching). In further embodiments, pocket 106 may include a pouch-like structure coupled to cuff body 104 into which stimulation device 108 may be inserted. The stimulation device 108 may be passively held within the pouch-like pocket by simply inserting the device 108 into the pocket, or may be actively held by fastening means. The pouch-shaped pocket may be disposed inside or outside the cuff body 104. Pocket-like pocket 106 and/or cuff body 104 may include access openings to allow electrodes to be positioned directly adjacent or proximate to nerve 102.

The cuff body 104 may have a uniform thickness or a varying thickness, as shown in fig. 9A and 9B. The thickness of the cuff body 104 may be determined to reduce the profile of the device that is accessible once the stimulation device is inserted. In one embodiment, the thickness of the cuff body may range from about 1 mil to about 30 mils, or from about 5 mils to about 20 mils. In one embodiment shown in fig. 9B, the cuff 104 may have a greater thickness at the top and bottom portions of the cuff and a lesser thickness at the middle portion where the stimulation device is housed.

The main obstacle to overcome to get the stimulation device close to the nerve or nerve bundle is that the fragile nerve connections along the soft tissue constitute the rigid structure of the stimulation device. In one embodiment of the invention, this problem is accomplished by housing the nerve 102 and device 108 in an cuff body 104 that includes a low durometer material (e.g., Silastic) as described above^TMOr Tecothane^TM) And conformably surrounds the nerve 102. Further, as shown in fig. 2, cuff body 104 may include strain relief 114 at its ends to reduce or prevent tip torsion and prevent nerve 102 kinking. The strain relief 114 may be wrapped around the nerve 102 and may be fine tuned to a desired size, such as the size of the nerve 102. Further, the strain relief 114 may be tapered. In some variations, the lateral ends of the nerve cuff that form the channel within which the nerve may be placed are tapered and have a tapered thickness to provide some support to the nerve. In some variations, a channel through the nerve cuff within which a nerve may be placed is reinforced to prevent the nerve from being placed when within the cuffAxial loading (e.g., impingement) on the nerve or associated vascular structure is stopped or limited.

With the above-described design or configuration of cuff body 104, any vertical movement of cuff body 104 over nerve 102 is not critical to electrical performance, but can result in friction between device 108 and nerve 102 that can potentially damage nerve 102. To this end, the device 108 should be easy to move up and down the nerve 102 without significant friction, yet be sufficiently secure to the nerve 102 to eventually form connective tissue and help hold the device 108 in place. The challenge is to stabilize the device 108 so that it can be further biosolidated by connective tissue in weeks.

The nerve cuff 100 should not be secured around muscles or bandages that may move relative to the nerve. Thus, referring to fig. 3 and 4, the nerve cuff 100 may further include attachment means, such as suture holes or suture tabs, for attaching and securing the cuff body 104 with the device 108 to at least one of the nerve bundle or nerve 102 and the peripheral sheath containing the nerve 102. In one embodiment of the invention, such as shown in fig. 3, the cuff body 104 may include suture holes 106 that may be used with sutures to couple the cuff body 104 with the device 108 to a peripheral nerve sheath. In an alternative embodiment of the present invention, shown in FIG. 4, a suture tab 118 with suture holes 116 extends from one or both sides of the cuff body 104.

A variety of securing mechanisms may be used, including suture tabs and holes, staples, knots, surgical adhesives, ties, hook and loop fasteners, and any of a variety of coupling mechanisms. For example, fig. 3 and 4 illustrate suture tabs and holes that may be secured to a peripheral sheath by absorbable sutures for soft tissue or sutures requiring rigid fixation.

Figure 5 illustrates the suture 120 clamping or securing the cuff body 104 with the device 108 to the surgically selected tension. Suture 120 may be tight or loose depending on the desired stability and anatomical considerations. As shown in fig. 5, a void 122 may be left, as long as the cuff adapter 100 is sufficiently secured to the nerve 102, with a limit set to the nerve diameter to prevent compression of the vasculature in the nerve 102. Surgical adhesive (not shown) may be used in conjunction with suture 120 to the surrounding tissue that moves with the neural tissue.

Blocking muscle movement of cuff adapter 100 may transmit undesirable stresses to nerve 102. Thus, in one embodiment of the present invention, a low friction surface and/or a hydrophilic coating may be added to one or more surfaces of cuff body 104 to provide a further mechanism to reduce or prevent adjacent tissue from affecting the stability of nerve cuff 100.

Figure 6 shows nerve cuff 100 with a stimulation device removably or sack-like secured in a pocket or pouch 106 of cuff body 104. By using a re-closable bag 106, the active stimulator device 108 may be removed from or replaced in the cuff body 104 without injuring or compromising the surrounding anatomy and tissue. The device 108 may be secured within the enclosure body 104 by any of a variety of fastening means 124, such as sutures, staples, ties, zippers, hook and loop fasteners, snaps, buttons, and combinations thereof. Suture 124 is shown in fig. 6. Untying the sutures 124 allows access to the pocket 106 for removal or replacement of the device 108. Unlike conventional cuff-like leads, the capsule of connective tissue may naturally encase nerve cuff 100 over time. Thus, it is very likely that palpation of the device 108 may be necessary to locate the device 108 and cut the connective tissue pouch to access the suture 124 and the device. The removable/replaceable nature of the nerve cuff 100 is advantageous over other cuff-type leads because such leads are unlikely to be removed due to entanglement with the target nerve and critical vasculature.

As mentioned above, the compression of the nerve 102 must be carefully controlled. Over-compression of the nerve 102 may cause vessel rupture and death of the nerve tissue. Compression may be controlled by a large or sized nerve cuff 100 so that the nerve diameter is not reduced less than the measured diameter when the pocket suture 124 is maximally tightened. By Silastic^TMOr Tecothane^TMThe cuff of material is relatively inexpensive and therefore provides the surgeon performing the implantation of nerve cuff 100 with a variety of sizes to better avoid nerve compression.

Commercial cuff systems of the prior art, microstimulators such as devices, are still large enough to be felt and touched by the patient. Referring to fig. 7, to avoid such access, the nerve cuff 100 may further include a protective cover 126 shaped to conform to anatomical structures in, for example, the carotid sheath. In this embodiment, the nerve cuff 100 is secured around the vagus nerve, while the nerve cuff also isolates the device 108 from contact with the Internal Jugular Vein (IJV)132 and common carotid artery 134. The boot 126 further isolates the device 108 from other surrounding tissue. In keeping with e.g. Silastic^TMOr Tecothane^TMIt is critical that the compliance of the material minimize the profile of the entire envelope adapter 100. In one embodiment of the invention, the protective cover 126 is made of a PET material (e.g., Dacron @)) Formed, optionally coated with Silastic^TMOr Tecothane^TMA thin, compliant structure is formed that allows tissue separation when desired.

Additional structure may be included in cuff body 104 or on cuff body 104 when the nerve is unable to provide sufficient structural strength to support nerve cuff adapter 100. Due to the high degree of anatomical variation, this solution must require the skill of the surgeon to utilize an extremely specialized solution. Figure 8A shows a variable size nerve cuff 100 with a wrappable retention portion 128 extending from the cuff body 104. As shown in fig. 8C, cuff body 104 is secured around nerve 102, while retaining portion 128 is secured around a sheath or other surrounding anatomical structure, such as IJV132 and/or carotid artery 134. As shown in fig. 8B, the wrappable retention portion 128 can include a fastening device 130, such as a suture hole, for fastening the entire nerve cuff 128 about the desired anatomical structure. This configuration allows access to the device 108 through the pocket 106 as in the previous embodiment, while accommodating most anatomical differences to achieve the desired stability of the nerve cuff 100 on the nerve 102.

Figures 10A-10D illustrate a variation of a nerve cuff that includes a cuff body that forms a channel in which a nerve may be placed and a slit formed along the length of the nerve cuff body. In this example, the nerve cuff body also includes a pocket area within the cuff body above the nerve channel. The top of the body (facing away from the neural canal) includes a long slit 1003 along its length, forming an opening. The wrapper may be separated along the slit by pulling apart the edges forming one or more of the side flaps. In the example shown in fig. 10A, the slit may be split to expose the inside of the nerve cuff, allowing the nerve to be placed in the internal passage, thereby positioning the cuff around the nerve. The same slot may also be used for inserting a microcontroller. In some variations, a separate opening (slit or flap) may be used to access the pocket or pouch for the microcontroller.

Fig. 10B shows a perspective view of a nerve cuff that holds a microcontroller after it is inserted onto a nerve (e.g., the vagus nerve). Fig. 10C shows a side view as above. Fig. 10D illustrates a cross-section of the diagram of fig. 10C, thus showing a nerve positioned within a channel formed through the nerve cuff, and a microstimulator held snugly within the nerve cuff, such that the microstimulator and the nerve are in electrical communication through a common surface therebetween. In some variations, as will be discussed below, the microstimulator is held in a separate, possibly insulated, compartment, and this electrical contact with the nerve is made through one or more internal leads that will couple the microstimulator with the nerve through internal contacts.

The exemplary envelope shown in fig. 10A through 10D has a compliant structure in which the wall thickness is relatively constant, as seen in the cross-sectional view of fig. 10D. In contrast, figures 11A to 11D show a variation of the nerve cuff in which the wall thickness varies along the circumference. This inconsistent thickness can effectively provide cushioning for the device relative to the surrounding tissue even if the patient moves or touches this area. This method has the added benefit of protecting the nerve from impingement. Similarly, the varying thickness may enable a smooth transition and help the cuff conform to the surrounding anatomical anatomy.

For example, fig. 11A shows an end view (shown in exemplary dimensions). It should be noted that all figures and examples, dimensions shown or described herein are provided for illustration only. In practice, the size may be some percentage (e.g., +/-5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, etc.) of the value shown plus or minus (+/-). The cross-section of the device shown in fig. 11D shows the non-uniform thickness of the wall.

Both of the nerve cuff variations shown in figures 10A-10D and in figures 11A-11D are substantially rounded or compliant, with atraumatic (or atraumatic) outer surfaces. As already mentioned, such a relatively smooth outer surface may enhance comfort and limit encapsulation of the nerve cuff within tissue.

As can be seen from fig. 10D and 11D, the microstimulator, when inserted into the nerve cuff, is generally located above (in the reference plane of the drawings) the lengthwise direction of the nerve. In some variations, the microstimulator includes a contoured outer surface on which one or more contacts (for contacting a nerve or an inner conductor within a nerve envelope) are disposed. For example, fig. 12 shows a variation of microstimulator 1201. In this example, the microstimulator includes one or more contacts on its outer surface through which stimulation is provided to the nerve. Fig. 13A shows another variation of a microstimulator 1301, in which the outer surface (bottom of fig. 13A) is curved to help form a channel around the nerve when the microstimulator is inserted into the nerve cuff. Fig. 13B illustrates an end view showing channel recesses 1303 extending along the length of the microstimulator, and fig. 13C illustrates a bottom view looking into the channel area. In practice, the microstimulator shown may be placed inside the nerve cuff and positioned at least partially around the nerve. Thus, the microstimulator may help protect nerves located within the channel. As mentioned above and described in more detail below, the nerve need not rest on a contact because current can be conducted from inside the nerve cuff to the nerve, which can be sufficiently insulated to prevent excessive leakage or overflow of current even when the cuff is too large or can only loosely surround the nerve. In addition, the nerve cuff may contain one or more internal contacts that allow current to be distributed to the nerve via one or more internal contacts or leads, including circumferentially around the nerve.

Figures 14A and 14B illustrate another variation of the nerve cuff. In this example, the slit forming the opening is located on the upper surface (opposite the neural channel) along the length of the device. The slits are formed in an interconnected pattern. In fig. 14A, the slits form a zigzag pattern, although other interconnect patterns may be used. For example, a sinusoidal or square waveform pattern may be used. This interlocking pattern may distribute the stresses that enclose the nerves and the microstimulator, and may more easily enclose the cuff when the cuff has been positioned and the microstimulator has been inserted. Figure 14B shows an end view of the same cuff shown in figure 14A.

Fig. 15A to 15C show similar cuffs as shown in fig. 14A connected to nerves in top and side views. In this example, the nerve extends through the internal channel and out an opening (which may be oval-shaped, as shown in fig. 14B) at both ends. In fig. 15C, a cross-section along the length of the device shows the microstimulator positioned in a pocket (lumen) above the nerve. The microstimulator may be held in place by the wall of the cuff. As shown in the cross-sectional view of fig. 15D, a compliant microstimulator (such as the one shown in fig. 13A-13C) may be used. The contacts 1503 of the compliant microstimulator are disposed at the bottom of the device.

As briefly mentioned above, in some variations of the nerve cuff, the inner surface of the cuff body includes one or more internal contacts configured to couple with a microstimulator held inside the bag and transmit any applied energy to (or receive energy from) a nerve disposed within the channel through the nerve cuff. The internal lead may be arranged so that it can provide current to the underside (along the bottom region of the channel) or around the side of the nerve when the nerve is within the channel. In some variations, the inner conductor or lead is configured to encircle the channel, so that the nerve can be stimulated circumferentially, optimizing the applied stimulation. Figure 17 is a long section of the nerve cuff showing the inside of the cuff and showing a variation of the nerve cuff with an internal lead 1703 that can apply stimulation to the underside of the nerve. This internal lead may be formed of any biocompatible conductive material, including metal, conductive plastic, or the like. The inner lead may include an exposed electrode surface 1703 for making contact with the nerve. The electrodes may be active contacts and also be formed of any suitable conductive material (e.g., metal, conductive polymer, woven material, etc.). In some variations, the inner wire is coated or treated to help enhance the transfer of energy between the microstimulator and the nerve. Circumferential stimulation or conduction around the lead may reduce impedance and ensure consistent cross-sectional stimulation of the nerve bundle.

Figure 19 illustrates another variation of the nerve cuff described herein. In this example, the nerve cuff includes a slit 1903 along one side of the device, near the nerve channel, which can be opened (e.g., by pulling the side wings or sides of the cuff) to expose the nerve channel, and a pocket for the microstimulator.

The various nerve cuff variants described herein may be opened and positioned around the nerve, for example, by splitting it open along a slit or hinge region. The devices are constructed so that they are sufficiently resilient to close on themselves, or remain closed when the edges of the slit area are brought together. Thus, the device may have a shape memory function that causes it to close. In some variations, as already mentioned, it is useful to keep them at least temporarily closed once they have been positioned on the nerve and the microstimulator has been positioned in the pocket. Thus, the device may also comprise one or more closing elements. For example, the device may include a suture hole or port for suturing the device closed. In some variations, the nerve cuff includes snaps or other fastening elements. In some variations, the device may be sutured closed with dissolvable sutures, as shown in fig. 6 and 18. After several weeks or months of insertion, the nerve cuff will be encapsulated or engulfed by the surrounding tissue and will be held closed by such encapsulation. Thus, such dissolvable sutures merely hold the envelope closed for initial anchoring before bio-integration and encapsulation occurs.

All of the nerve cuffs described herein may also include one or more external leads or contacts that are directed toward the outside of the body of the nerve cuff, which are used to stimulate tissue outside the nerve cuff, not just the nerve that passes through the cuff within the channel. Figure 21 shows a variation of a nerve cuff with external leads. In this example, the nerve cuff includes two external contacts 2103 that connect (through the wall of the nerve cuff body) to a microstimulator held within the nerve cuff pocket. Such external leads may be used for sensing in addition to (or instead of) stimulation. For example, these electrical contacts may be used to sense other physiological phenomena, such as muscle stimulation and/or cardiac function. These signals can be used to assist in the synchronization of targeted neural stimulation to minimize artefacts of targeted stimulation. Such signals may be too weak for reliable remote sensing, whereas the location of the microstimulator (insulated within the housing of the nerve cuff) may allow accurate and reliable sensing.

The nerve may be placed in a supported channel through the nerve cuff. As shown in fig. 20, the channel 2003 may be formed to have generally smooth sides to prevent damage to nerves and associated tissue. In some variations, the nerve channel through the cuff is reinforced to prevent the cuff from stressing or over-tightening the device when closed on the nerve. The buttress may be formed of a different material than the nerve cuff body or of a thickened region of the same material. While nerve cuffs of various sizes may be used (e.g., large, medium, small), in some variations, oversized nerve cuffs may be used because the insulating cuff prevents current leakage from the microstimulator to the surrounding tissue.

In general, the nerve cuff body may be electrically insulating, preventing leakage of electrical charge from the microstimulator during operation. In some variations, the nerve cuff includes shielding or insulation sufficient to electrically insulate the microstimulator within the nerve cuff. The shielding material may particularly comprise an electrically insulating material, including a polymer insulator.

It can be shown mathematically with the equivalent circuit of the microstimulator as shown in fig. 23 that the current from the microstimulator does not flow significantly out of the nerve cuff even if it is loosely applied. This allows the use of oversized nerve cuffs without the need for critical dimensions or the risk of compressing the nerve.

For example, assume a cross-section of N_areaThe nerve of (a) is a fluid column F enclosed by the nerve cuff_areaEncircling, in the nerve cuff, contact separation E in the microstimulator_spacing(midpoint to midpoint) and has a width E_widthAnd surrounding fluid column and nerve E_degreesIt can be seen that the current will travel the distance between the midpoint of the electrode and the end of the nerve cuff (this distance is represented by distance D)_guardDefinition) to the outside.

The electrical model (shown in FIG. 23) is driven through a DC isolation capacitor (optional C)_iso2) Capacitance (C) through each electrode_dl1And C_dl2) Of the current source. The current flows from the electrode through the path R_SOr R_lp1+R_b+R_lp2. Flows through R as part of the current_SProvides efficient operation and flows through R_lp1+R_b+R_lp2May cause undesirable effects by flowing current to the outside of the device.

If nerveWith a tight fit, all flow through R_SAll of the current will be used for stimulation, but in the case of loose fitting, only a portion of the current may stimulate the nerve. Based on this model, it can be seen (assuming that the nerve and fluid columns form an ellipse defined by major and minor axes a and b, and that the pulse width is short and the capacitance is large) that only real impedance and efficiency can be evaluated.

The electrode surface area is determined for evaluating the complex part of the impedance: f_area＝π*a_F*b_FAnd N_area＝π*a_N*b_N。

Assuming that the impedance of the cuff containing the fluid and the nerve has an approximate conductance ρ and the electrodes are at E_spacingInterval, then the real resistance of the conduction quantity is: r_working＝E_spacing*ρ/F_areaWherein by R_wasted＝2*D_guard*ρ/F_area+R_bulkCalculating the loss resistance that should be maximized, where R_bulkDefined as the free field resistance between the two ends of the envelope.

Therefore, the efficiency (η) of real current input into the POD is R_wasted/(R_working+R_wasted) In the case of undersized nerves, the stimulation efficiency is defined as η assuming approximately equal conductivities of the tissue and fluid columns_T＝η*N_area/F_area。

Method of insertion

During surgery, any of the devices described herein may be placed around a nerve and a microstimulator inserted into the nerve cuff in any suitable manner. Figures 22A through 22H illustrate a variation of a method for applying a nerve cuff around a nerve and inserting a microstimulator. In this example, the patient is prepared to add a nerve cuff around the vagus nerve to hold the microstimulator device securely against the nerve (fig. 22A). An incision (≈ 3 cm) is then made in the skin along the langer crease between the facial vein and the hyoglossus (fig. 22B), and the sternocleidomastoid muscle is retracted to access the carotid sheath (fig. 22C). The IJV is then reflected and the vagus nerve ≦ 2 cm is isolated from the carotid artery wall.

In some variations, a sizer may be used to measure the vagus nerve (e.g., diameter) to select the appropriate microstimulator and cuff (e.g., small, medium, large). In some variations of this method, an oversized envelope may be used, as described above. The nerve cuff is then placed under the nerve with the opening into the nerve cuff facing the surgeon (fig. 22D), which enables access to the nerve and the pocket holding the microstimulator. The microstimulator may then be inserted inside the cuff (fig. 22E) while ensuring that the microstimulator contacts are either aligned with the vagus nerve, or in communication with the vagus nerve with any internal contacts/leads. The nerve cuff may then be sutured closed (fig. 22F). In some variations, the microstimulator may then be tested (fig. 22G) to determine that the device is working and has been coupled to a nerve. For example, a surgical testing device covered under a sterile plastic cap can be used to activate the microstimulator and perform system integrity and impedance checks, and then shut down the microstimulator. This procedure can be repeated as necessary to properly position and attach the microstimulator. Once completed and verified, the incision can be closed (fig. 22H).

The present invention may be embodied in other specific forms without departing from its essential attributes; the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The claims provided herein are for the purpose of ensuring that the present application is adapted to establish foreign priority and for no other purpose.

Claims (26)

1. A nerve cuff for ensuring stable communication of a leadless microstimulator with a nerve, the nerve cuff comprising:

a cuff body having a channel extending within a length of the cuff body for passage of a nerve;

a pocket inside the cuff body, the pocket configured to removably retain a leadless microstimulator; and

an elongated opening slit extending along a length of the cuff body, the opening slit configured to open to provide access to a bag.

2. The nerve cuff of claim 1, further comprising an internal electrical contact within the cuff body.

3. The nerve cuff of claim 2, wherein the internal electrical contacts are configured to electrically couple the leadless microstimulator and the nerve.

4. The nerve cuff of claim 1, further comprising an external electrical contact on an outer surface of the cuff body, the external electrical contact configured for coupling with the leadless microstimulator.

5. The nerve cuff of claim 1, wherein the cuff body includes a shield configured to electrically insulate the leadless microstimulator within the nerve cuff.

6. The nerve cuff of claim 1, wherein the cuff body has a uniform thickness.

7. The nerve cuff of claim 1, wherein the cuff body has a non-uniform thickness.

8. The nerve cuff of claim 7, wherein the cuff body has a thickness of between about 5 mils and about 20 mils.

9. The nerve cuff of claim 1, wherein an outer surface of the nerve cuff is substantially smooth and atraumatic.

10. The nerve cuff of claim 1, wherein the outer surface of the nerve cuff is rounded.

11. The nerve cuff of claim 1, wherein the channel comprises a support channel configured to support a nerve therein to prevent compression of the nerve.

12. The nerve cuff of claim 1, wherein the elongated open slit extends along a length of the cuff body in an interconnected pattern.

13. The nerve cuff of claim 1, wherein the open slit extends along a side of the cuff body proximate the channel.

14. The nerve cuff of claim 1, further comprising an attachment site in the elongated opening slit configured to help ensure closure of the opening slit.

15. The nerve cuff of claim 1, wherein the cuff body is formed from a flexible and biocompatible polymer.

16. A nerve cuff for ensuring stable communication of a leadless microstimulator with a nerve, the nerve cuff comprising:

an insulating cuff body having a nerve channel extending within a length of the cuff body for passage of a nerve, wherein the cuff body electrically insulates a leadless microstimulator within the cuff body;

a conductive surface within the neural pathway, the conductive surface configured to engage one or more electrical contacts on the leadless microstimulator;

a pocket inside the cuff body, the pocket configured to removably retain a leadless microstimulator; and

an elongated opening slit extending along a length of the cuff body, the opening slit configured to open to provide access to a bag.

17. The nerve cuff of claim 16, further comprising an external electrical contact on an outer surface of the cuff body, the external electrical contact configured for coupling with the leadless microstimulator.

18. The nerve cuff of claim 16, wherein the cuff body has a uniform thickness.

19. The nerve cuff of claim 16, wherein the cuff body has a non-uniform thickness.

20. The nerve cuff of claim 19, wherein the cuff body has a thickness of between about 5 mils and about 20 mils.

21. The nerve cuff of claim 16, wherein an outer surface of the nerve cuff is substantially smooth and atraumatic.

22. The nerve cuff of claim 16, wherein an outer surface of the nerve cuff is contour-matched.

23. The nerve cuff of claim 16, wherein the channel comprises a support channel configured to support a nerve therein to prevent compression of the nerve.

24. The nerve cuff of claim 16, wherein the elongated open slit extends along a length of the cuff body in an interconnected pattern.

25. The nerve cuff of claim 16, further comprising an attachment site in the elongated opening slit configured to help ensure closure of the opening slit.

26. The nerve cuff of claim 16, wherein the cuff body is formed from a flexible and biocompatible polymer.