Medical implant having an electrode arrangement in the form of a wrap-around cuff

Abstract

The invention relates to a medical implant having an electrode arrangement in the form of a wrap-around cuff, cuff electrode for short, suitable for extravascular or extraneuronal securing along an intracorporeal vessel or a nerve cord, which is connected to a flexible electrical supply and discharge arrangement having a longitudinal extension, which is surrounded by a sheathing body along a section of its longitudinal extension, which serves to secure the electrical supply and discharge arrangement to an intracorporeal tissue structure. The invention is characterized in that a support body having a bioresorbable material is provided, which at least partially surrounds the flexible electrical supply and discharge arrangement and the sheathing body.

Description

[0001] Medical implant with an electrode arrangement designed as a wrap-around cuff

[0002] Technical field

[0003] The invention relates to a medical implant with an electrode arrangement designed as a wrap-around cuff, or cuff electrode for short, suitable for extravascular or extraneuronal attachment along an intracorporeal vessel or nerve tract, which is connected to a flexible electrical input and output arrangement having a longitudinal extension, which is surrounded along a section in its longitudinal extension by a sheathing body that serves to fix the electrical input and output arrangement to an intracorporeal tissue structure.

[0004] State of the art

[0005] The publication EP 3204 105 B1 discloses a cuff electrode arrangement, also known as a cuff electrode, consisting of a flexible, biocompatible, film-like carrier substrate, preferably a polyimide film. A plurality of individual electrodes are arranged on at least one surface of the carrier substrate. The known cuff electrode serves for the spatially resolved acquisition of neuronal electrical signals and for the selective electrical stimulation of individual nerve fibers running within a nerve fiber bundle. For the purpose of electrical power and signal supply, all electrodes of the cuff electrode are connected to electrical conductors, which in turn are connected to a supply implant designed separately from the cuff electrode.The surgical implant is usually implanted subcutaneously in a surgically accessible area, such as the chest or near the collarbone, while the cuff electrode is applied several centimeters away, preferably along the vagus nerve. To ensure the most tissue-sparing electrical energy and signal transmission between the surgical implant and the cuff electrode, the required electrical connecting cable should have the smallest possible cross-section and a length sufficient to compensate for relative movements between the implant sites. Typically, the connecting cable is connected to the surgical implant via a detachable, fluid-tight connector and to the cuff electrode either via a fixed electrical contact or another connector.Both connection methods are explained in publication DE 102017209773 A1. In both cases, a carrier plate, usually made of ceramic material, serves to electrically connect the numerous electrical conductors arranged on the cuff electrode side to the connecting cables grouped together to form the electrical connection cable. The numerous electrical contacts are arranged on this carrier plate by means of bond or solder connections.

[0006] To protect against moisture and the ingress of intracorporeal water, this contacting structure, or at least parts of it, is surrounded by a sheath made of biocompatible, electrically insulating material. Besides its sealing function, the sheath, due to its macroscopic dimensions and shape, also facilitates manual handling of the cuff electrode during implantation for the surgeon. The sheath, preferably made of an elastic silicone material, typically has a cylindrical or ellipsoidal shape, with a longitudinal extent typically of at least 1 cm and a diameter of a few millimeters. Furthermore, the sheath serves as a kind of mechanical counter-support for additional attachment of the cuff electrode, which, in its implanted state, tightly encloses a bundle of nerve fibers, preferably the vagus nerve, in a cuff-like manner.To avoid shear and, above all, tensile forces acting directly on the cuff electrode along the connecting cable, which can be caused by body movements, these forces are absorbed or redirected into the surrounding tissue by an additional mechanical fastening of the sheathing body to immediately surrounding tissue areas.

[0007] In practice, the additional intracorporeal fixation of the sheath body to a tissue area adjacent to the vagus nerve has proven effective only insofar as securing the sheath body with a surgical suture ensures a largely constant relative distance between the sheath body and the cuff electrode, which surrounds the vagus nerve like a cuff, and is thus able to absorb the tensile forces acting along the connecting cable. See in this context German patent application DE 102023 126781 A1, which discloses a joining technique for a sheath body using surgical sutures. However, it has been shown that the ideal relative position between the sheath body and the cuff electrode, as determined by the surgeon, is already compromised immediately after completion of the implantation, i.e.,After removal of the tissue retractor required for implantation access, the position of the sheathing body changes due to the elastic restoring forces acting within the tissue immediately surrounding the sheathing body, following the removal of the external mechanical constraint imposed by the implantation. This indeterminate spatial position of the sheathing body relative to the cuff electrode results in a correspondingly undefined spatial path for the flexible electrical lead-in and lead-out arrangement extending between the cuff electrode and the sheathing body. This arrangement, like the cuff electrode's substrate, is made of a film-like, flat substrate identical to the substrate and extends in a band-like fashion between the cuff electrode and the sheathing body.Particularly in cases where the sheathing body ultimately lies laterally to the vagus nerve, the flexible electrical input and output arrangement is deformed laterally to its otherwise assignable longitudinal band extension, which can cause local material stretching and compression within its foil-like, band-shaped surface substrate, even leading to material kinks, which can be the cause of subsequent material failure, unnecessarily limiting the service life of the implanted cuff electrode.

[0008] Description of the invention

[0009] The invention is based on the objective of further developing a medical implant with an electrode arrangement designed as a cuff, or cuff electrode for short, suitable for extravascular or extraneuronal fixation along an intracorporeal vessel or nerve tract, which is connected to a flexible electrical input and output arrangement having a longitudinal extension, which is surrounded along a section in its longitudinal extension by a sheathing body that serves to fix the electrical input and output arrangement to an intracorporeal tissue structure, in such a way that even after the implantation of the cuff electrode, e.g. along the vagus nerve, the spatial arrangement of the cuff electrode and the flexible electrical input and output arrangement directly connected to it, as determined by a surgeon, is maintained as permanently as possible.In particular, measures must be taken to prevent the flexible electrical supply and drainage arrangement extending between the cuff electrode and the casing body from deforming laterally to its longitudinal extent, or in the worst case, from kinking, in order to avoid potential points of damage and to increase the service life of the medical implant.

[0010] The solution to the problem underlying the invention is specified in claim 1. Advantageously developing features of the invention are the subject of the dependent claims and the further description with reference to the exemplary embodiments.

[0011] The medical implant according to the solution, comprising the features of the preamble of claim 1, is characterized by the provision of a support body made of bioresorbable material, which at least partially surrounds the flexible electrical lead assembly and the sheathing body. The support body ensures a stable connection between the cuff electrode, the sheathing body, and the flexible electrical lead assembly running between the cuff electrode and the sheathing body, even and especially after completion of all implantation procedures performed on the patient. For this purpose, the material, shape, and size of the support body are selected such that the shape of the flexible electrical lead assembly and its relative position to the cuff electrode and the sheathing body are maintained after implantation.

[0012] The support body surrounds the flexible electrical supply and discharge arrangement along at least one longitudinal section between the cuff electrode and the sheathing body, and at least one part of the sheathing body facing the flexible electrical supply and discharge arrangement, preferably in one piece, i.e. monolithically.

[0013] To ensure that the support body is not subject to any deformations that could otherwise be caused immediately after the surgical procedure by tissue-inherent elastic restoring forces acting on the support body, the bioresorbable material of the support body has an E-modulus that is preferably equal to or greater than an E-modulus attributable to the band-shaped, foil-like surface substrate of the flexible electrical supply and discharge arrangement and / or particularly preferably greater than an E-modulus attributable to the surrounding tissue.

[0014] The support body, which preferably encloses at least a portion of the sheathing body and at least a longitudinal section of the flexible electrical input and output arrangement, is tubular, i.e., cylindrical or conically expanding, and surrounds the flexible electrical input and output arrangement flush, forming a solid material matrix. In a particularly preferred embodiment, the support body encompasses the flexible electrical input and output arrangement between the sheathing body and the cuff electrode almost completely, extending to just before the cuff electrode. A small gap between the support body and the cuff electrode ensures complete contact of the cuff electrode with the epineurium of the nerve cord.The end region of the tubular support body facing the cuff electrode is designed with the thinnest possible walls to minimize the distance between the flexible electrical input and output arrangement and the epineurium of the nerve bundle when the cuff electrode is placed around the nerve. The diameter of the support body, which completely surrounds the flexible electrical input and output arrangement, widens towards the outer sheath and adapts to the outer sheath's maximum diameter. Typically, the outer sheath is cylindrical or elongated ellipsoidal, to which the support body fits, preferably seamlessly and flush on one side. Preferably, the outer sheath and the support body together form a seamless, uninterrupted, and edgeless surface.

[0015] The bioresorbable material of the support structure dissolves continuously within the body after implantation until the support structure is completely resorbed and thus disappears. The rate of material resorption is preferably adapted to tissue growth. Following implantation, the body's natural healing process begins, causing new tissue to form around the implant and firmly anchoring the medical implant within this newly formed tissue. During the healing process, the bioresorbable material of the support structure degrades and is completely replaced by the surrounding tissue. The biological tissue enveloping the implant then takes over the function of the support structure. In this way, the implant automatically reduces itself to the essential functional components that are absolutely necessary for the therapeutic goal underlying the implant.

[0016] Bioresorbable polymers are particularly suitable for the supporting structure, e.g.

[0017] Polylactides, especially in the form of poly-D, L-lactic acid (PDLLA).

[0018] Brief description of the invention

[0019] The invention is described below by way of example, without limiting the general concept of the invention, with reference to the drawings. Figure 1 shows a medical implant comprising a cuff electrode, a sheathing body, and a flexible electrical supply and drainage arrangement extending between the cuff electrode and the sheathing body, according to the prior art.

[0020] Fig. 2 solution-oriented medical implant with support body as well as

[0021] Fig. 3 Solution-oriented medical implant with support body applied along a nerve strand.

[0022] Ways to implement the invention, industrial applicability

[0023] Figure 1 shows a medical implant 1, which consists of a cuff electrode 2 wrapped around or attached to a nerve tract 3, a flexible electrical input and output arrangement 4 directly connected to the cuff electrode 2, and a sheathing body 5. For details of the function and the technical design of the cuff electrode 2, reference is made to the aforementioned publication EP 3204 105 B1.

[0024] The flexible electrical supply and drainage arrangement 4, running between the cuff electrode 2 and the sheathing body 5, has a ribbon-shaped, film-like substrate, preferably made of polyimide, which is monolithically bonded to the support substrate of the cuff electrode 2 and in which a plurality of electrical conductors are embedded. These conductors are connected, on the one hand, individually to electrical contacts attached to the cuff electrode 2 and, on the other hand, via a bond or solder connection attached to a rigid connection structure, preferably in the form of a ceramic carrier plate, to a further electrical conductor. The latter are combined to form a single connecting cable 6, which is connected to an intracorporeal supply unit separate from the medical implant 1.For the sake of simplicity and clarity, the graphic representation of the electrical conductors embedded in the flexible electrical supply and drainage arrangement 4, the electrical contacts in the cuff electrode 2, the separate intracorporeal supply unit, and the rigid connection structure enclosed within the sheathing body 5 in a fluid-tight manner relative to the environment has been omitted.

[0025] The film-like material of the band-shaped, film-like surface substrate of the flexible electrical input and output arrangement 4 is flexible but not elastic, so that, for the purpose of length compensation, it is at least partially wavy in shape between the sheathing body 5, which is fixed to the surrounding tissue (not shown), preferably by means of a surgical suture, and the cuff electrode 2 attached to the nerve cord 3. This wavy shape gives the band-shaped surface substrate of the electrical input and output arrangement 4 a high degree of flexibility in almost all spatial directions. Preferably, the wavy section of the band-shaped surface substrate of the flexible electrical input and output arrangement 4 abuts the sheathing body 5 on one side.Between the wavy section and the cuff electrode 2, the band-shaped surface substrate runs almost flat and straight to allow complete surface contact between the cuff electrode 2 and the epineurium of the nerve tract 3.

[0026] Should the sheathing body 5, fixed to the surrounding tissue, assume a position deviating from the ideal position shown in Figure 1 relative to the cuff electrode 2 attached to the nerve cord (where the longitudinal extent of the band-shaped surface substrate of the electrical input and output arrangement 4 is oriented almost parallel to the nerve cord 3 and to the cuff electrode 2 resting on the nerve cord 3), for example, protruding laterally to the nerve cord 3, this would inevitably lead to a curved course of the band-shaped surface substrate of the electrical input and output arrangement 4. In this case, there is the aforementioned risk of material fatigue or fracture of the band-shaped surface substrate during long-term or continuous use of the medical implant 1, and consequently, total failure of the medical implant 1.

[0027] To avoid this, the medical implant 1 according to the solution illustrated in Figure 2 provides a support body 7 made of bioresorbable material, which surrounds at least the wave-shaped section of the ribbon-like, film-like surface substrate of the elastic electrical input and output arrangement 4 as well as a part of the sheathing body 5. The bioresorbable material of the support body 7 surrounds the ribbon-like, film-like surface substrate of the electrical input and output arrangement 4 in a matrix-like manner, i.e., as a solid material, and has a cross-sectional shape that increases in size from the side of the cuff electrode 2, conforming flush to the cross-sectional shape of the pill-shaped or ellipsoidal sheathing body 5 on one side.On either side of the cuff electrode 2, the support body 7 terminates with a small gap a to the cuff electrode 2 to ensure full-surface contact of the cuff electrode 2 along its entire axial extent with the epineurium of the nerve tract 3. Figure 3 shows the medical implant 1 applied along the nerve tract 3 in its ideal position relative to the nerve tract 3. A surgeon fixes the sheathing body 5 to a surrounding tissue structure (not shown in Figure 3). The support body 7 ensures that the medical implant 1 maintains its precise position relative to the nerve tract 3. The presence of the support body 7 prevents the elastic electrical lead assembly 4 from kinking at the transition to the sheathing body, as well as from unintentionally folding the elastic sheathing, both during and, in particular, after the implantation procedure.

[0028] Furthermore, the bioresorbable support body 7 allows the relative position and orientation, in terms of angle and distance, between the cuff electrode 2 and the sheathing body 5 to be individually determined during the manufacturing of the medical implant 1 by selecting the shape and size of the support body 7. In addition, the shape of the band-shaped surface substrate, particularly in the area of ​​the corrugated section, can be individually specified and defined with regard to amplitude and wavelength. In this way, longitudinal and transverse stress relief can be achieved within the corrugated section, which is maintained even after implantation.

[0029] The support body 7, consisting entirely of bioresorbable material, dissolves completely within a defined period after implantation and is replaced by the body's own tissue. Both the implantation position and the shape of the medical implant 1 are retained. Thus, with reference to Figure 1, it is assumed that the support body 7 has completely dissolved and that the medical implant 1, in the illustrated position and shape, is surrounded by the body's own tissue (not shown). [List of reference symbols]

[0030] 1 medical implant

[0031] 2 Cuff electrode

[0032] 3 nerve strand

[0033] 4 flexible electrical supply and discharge arrangement 5 sheathing body

[0034] 6 connecting cables

[0035] 7 support bodies

[0036] a distance between the flexible electrical supply and discharge arrangement and the cuff electrode

Claims

Patent claims 1. Medical implant (1) with an electrode arrangement designed as a wrap-around cuff, or cuff electrode (2), suitable for extravascular or extraneuronal fixation along an intracorporeal vessel or nerve tract (3), which is connected to a flexible electrical input and output arrangement (4) having a longitudinal extension, which is surrounded along a section in its longitudinal extension by a sheathing body (5) which serves to fix the flexible electrical input and output arrangement (4) to an intracorporeal tissue structure, characterized in that a support body (7) comprising a bioresorbable material is provided which at least partially surrounds the flexible electrical input and output arrangement (4) and the sheathing body (5).

2. Medical implant according to claim 1 , characterized in that the support body (7) surrounds the flexible electrical supply and discharge arrangement (4) along at least one longitudinal section and at least one partial area of ​​the sheathing body (5) facing the flexible electrical supply and discharge arrangement (4) in one piece, i.e. monolithically.

3. Medical implant according to claim 2, characterized in that the support body (5) is tubular in shape.

4. Medical implant according to one of claims 1 to 3, characterized in that the bioresorbable material is a bioresorbable polymer.

5. Medical implant according to one of claims 1 to 4, characterized in that the flexible electrical supply and discharge arrangement (4) comprises a plurality of electrical conductors embedded in a ribbon-shaped, foil-like surface substrate, that the ribbon-shaped, foil-like surface substrate has two ribbon ends, one of which is monolithically connected to a foil-like surface substrate attributable to the cuff electrode (2) and the other ribbon end adjoins a rigid connecting structure, that at least one section of the ribbon-shaped, film-like surface substrate adjacent to the connecting structure is wavy, and that the support body (7) surrounds at least the wavy section of the ribbon-shaped, film-like surface substrate as well as a part of the sheathing body (5).

6. Medical implant according to claim 5, characterized in that the plurality of electrical conductors are each connected on the one hand to an electrode attached to the cuff electrode (2) and on the other hand to an electrical contact attached to the rigid connecting structure, from which an electrical conductor leads, the plurality of electrical conductors of which are combined to form an implantable connecting cable, and that the sheathing body (5) completely surrounds the rigid connection structure.

7. Medical implant according to any one of claims 1 to 6, characterized in that the casing body (5) is cylindrical or in the form of an elongated ellipsoid, and that the support body (7) is joined to the casing body (5) at least on one side.

8. Medical implant according to claims 5 to 7. characterized in that the bioresorbable material of the support body (7) has an E-modulus that is equal to or greater than an E-modulus attributable to the ribbon-shaped, foil-like surface substrate of the flexible electrical supply and discharge arrangement (4).

9. Medical implant according to any one of claims 1 to 8, characterized in that the material, shape and size of the support body (7) are selected such that the shape of the flexible electrical supply and discharge arrangement (4) and its relative position to the cuff electrode (2) are maintained after implantation.

10. Medical implant according to any one of claims 1 to 9, characterized in that the bioresorbable material of the support body (7) is completely resorbable intracorporeally after implantation.

11. Medical implant according to any one of claims 4 to 10, characterized in that the polymer is from the group of polylactides, preferably poly-D, L-Lactic Acid (PDLLA).

Images