Patent Publication Number: US-2021178153-A1

Title: Electrode devices for neurostimulation

Description:
BRIEF DESCRIPTION 
     The present disclosure is related to embodiments of extravascular and intravascular devices containing electrodes for neurostimulation of a vessel. The devices are housed in flexible substrates, each substrate having a spine through which conductors for the electrodes are routed and housed. Extending from the spine are a plurality of curvilinear flaps or arms that support the electrodes and position the electrodes to either be inward facing, i.e., extravascular designs, or outward facing, i.e., intravascular designs. The substrate flaps or arms may include one or more electrodes and be configured to place one or more of the electrodes at specific positions relative to the target vessel. 
     BACKGROUND 
     Electrical devices of various shapes and sizes including one or more electrodes have been used for neurostimulation of target anatomy for years. U.S. Pat. No. 8,755,907 discloses an extravascular device including one or more electrode ribs interconnected by a spine, and optionally including one or more non-electrode ribs that serve to isolate the electrode ribs from movement and forces transmitted by cables near the non-electrode ribs. Both types of ribs are sized to fit the target anatomy and are positioned around the target vessel by separating the ribs, placing them around the target vessel, and closing them to secure them about the target vessel. The ends of the ribs may then be sutured in place, or not, but if not sutured the ends of ribs may be formed of a stiff material, including metal, provided it is electrically isolated from the electrodes. 
     U.S. Pat. Pub. No. 2016/0296747 discloses an intravascular neurostimulation device that may be collapsed so that it can be inserted into a catheter for positioning within a target vessel. Once in position, the distal end of the device is uncovered from the catheter, either by pushing the distal end of the device from the distal end of the catheter or removal of the catheter once the distal end of the device is in place. As disclosed, the device has a plurality of elongated balloon arms that have a number of electrodes positioned along the outer surface of each of the elongated balloon arms. As the device leaves the catheter, the device expands (i.e., balloons) so that the outer surface of each of the elongated balloon arms moves into contact with the interior walls of the target vessel in which it is placed. Other devices use a metal cage, typically formed of nitinol, with electrodes placed around the exterior surface of the cage, which are naturally biased to an expanded position, but can be compressed to fit within the catheter. 
     U.S. Pat. No. 9,283,379 discloses a cuff electrode assembly with a resilient body configured to be disposed about a target vessel. The cuff body includes a first end portion having a first free end, and a second end portion having a second free end, The cuff electrode assembly further includes a first arm member and a second arm member each projecting radially outward from the cuff body and spaced from one another along the cuff body. Application of a force pushing the first and second arm members toward one another defines an opening of the cuff body that allows the cuff body to be positioned around the target vessel. 
     U.S. Pat. No. 8,855,767 discloses an electrode cuff that includes a polymer cuff body having a pocket or pouch into which a target vessel can be positioned such that the electrodes of the cuff are proximate the nerve. 
     U.S. Pat. No. 7,925,352 discloses a cage-like electrode device with an array of electrodes disposed along a flexible elongated member that is configured to be positioned in contact with a target vessel wall. Pairs of rib-like structures, positioned at each electrode, contact the interior of the vessel walls to position the device. U.S. Pat. No. 9,216,280 discloses an electrode device that includes an elongated shaft and pairs of extending curvilinear arms or ribs extending from opposing sides of the elongated shaft. Each of the arms or ribs includes electrodes that make contact with the interior target vessel walls. 
     Each of the above examples illustrate a variety of existing different cuff-like and cage-like designs, with arms or flaps that are either perpendicular to the length of the target vessel, horizontal to the length of the target vessel, fit substantially fully around the target vessel and include exterior portions that can be used to open the cuff for placement and removal, or are more rigid in nature and cover only a portion of the target vessel. Such conventional designs lack radial flexibility and self-sizing capabilities. If the target vessel is excessively compressed by the device, nerve damage may result from the decreased blood flow and constricted nerve fibers. Temporary swelling of the target vessel caused by the trauma of the positioning of the device can exacerbate such nerve damage. In contrast, loose fitting devices can result in poor electrical contact and low treatment efficiency, which can further degrade over times as a result of ingrowth of connective tissue between the target vessel and the device. 
     Conventional helical or serpentine electrode devices address some of the limitations of conventional rigid cuff-like and cage-like devices, such as permitting some radial expansion that helps with post-positioning edema or swelling of the target vessel, more fluid exchange with surrounding tissue, better electrical contact, and reduced growth of connective tissue. Helical or serpentine devices, however, require a complex positioning effort that requires significant dissection and nerve manipulation in order to wind the helix around the nerve at least two times. Positioning of such devices also requires mobilization of a large portion of the nerve because the cathode and anode electrodes are typically positioned by their own device. 
     SUMMARY 
     According to one aspect of the present disclosure, there is a neural interface for interfacing with a target vessel, comprising: a first end portion, a second end portion and a center portion positioned between the first end portion and the second end portion, wherein the first end portion includes at least a first electrode and the second end portion includes at least a second electrode, wherein the first end portion, the second end portion and the center portion are each formed of a flexible material that is configured to enable each of the first end portion, the second end portion and the center portion to self-size to a surface of the target vessel when the neural interface is released at a position along the target vessel, and wherein neither the first end portion, the second end portion nor the center portion form a closed circumscribed circular arc around the target vessel at any point along a length of the target vessel; and a spinal portion configured to house electrical conductors for the first electrode and the second electrode, the spinal portion being connected to one or more of the first end portion, the center portion and the second end portion. 
     The first end portion, the second end portion and the center portion each have an initial configuration that is formed when these portions are in a rest state. The first end portion, the second end portion and the center portion are each biased towards the initial configuration, for instance when displaced from the initial position. In this way, it is possible for the first end, second end and center portions to self-size to the surface of the target vessel. This allows the neural interface to be positioned in a single pass around the nerve/vessel with minimal manipulation of the nerve/vessel and provides a reduction in tissue dissection around the area of the nerve/vessel where the interface is positioned. 
     The flexible material may be non-rigid and capable of elastic deformation (i.e. reversible deformation). In this way the first end portion, the second end portion and the center portion can each be displaced from their initial resting state into a different state in order to position the interface with respect to the target vessel. Then, when the interface is in an appropriate position the interface can be released allowing the portions to be urged back to their resting state, thus softly gripping the target vessel. 
     In the interface, none of the first end portion, the second end portion and the center portion forms a closed circumscribed circular arc around the target vessel at any point along a length of the target vessel. In other words, each one of the first end portion, the second end portion and the center portion form a gap when positioned around the target vessel. Thus, the target vessel can sit in alignment with the gaps formed by the portions, and therefore may serve to ensure that the target vessel may pulsate without constriction. In addition, the gaps provided by the portions allow an initially swollen target vessel to return to a normal state over time without constriction of the target vessel when it is swollen and without losing electrode to target vessel contact when the target vessel is in its normal state. 
     The spinal portion comprises an elongate member comprising a conduit for electrical conductors for the first electrode and the second electrode. In some examples, the spinal portion includes the electrical conductors. The spinal portion provides a simple and convenient arrangement for providing electrical connectivity to the first electrode and the second electrode. 
     The first end portion may be a positioned towards a first end of the neural interface and the second end portion may be positioned towards a second opposing end of the neural interface. The first end portion and second end portion may be positioned on opposite sides of the center portion. The first end portion, the second end portion and the center portion may be concentric with respect to one another. 
     The center portion may be referred to as an intermediate portion, since it is positioned between the end portions. The center portion may be positioned centrally with respect to the neural interface; however, the central/intermediate portion may be positioned at a location offset from the center of the neural interface. In addition, the center portion may be positioned equidistance from each end portion. Alternatively, the distance between the first end portion and the center portion may differ to the distance between the second end portion and the center portion. 
     The spinal portion may be an assembly made up of a plurality of parts. Each one of these parts may be connected, directly or indirectly, to one or more of the first end portion, the center portion and the second end portion. 
     In the present disclosure, a vessel refers to a vessel and a nerve (or nerves) that travels along with the vessel. The vessel may be an artery (or arteries) and/or a vein (or veins) and/or a lymph vessel (or lymph vessels). A nerve that travels along a vessel may be a nerve that is adjacent to the vessel or a nerve that is in the vicinity of the vessel. 
     In the present disclosure, a target vessel may be a target vessel that includes a nerve (or nerves) that travels along with the vessel. The target vessel may be an artery (or arteries), and/or a vein (or veins), and/or a lymph vessel (or lymph vessels). 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  is a perspective view of a first side of an embodiment of a bipolar electrode device including a flexible semi-helical structure for holding the electrodes and positioning the device; 
         FIG. 2A  is a perspective view of an opposite side of the embodiment of  FIG. 1 ; 
         FIG. 2B  is a perspective view of an embodiment of a multipolar electrode device including a flexible semi-helical structure similar to  FIG. 1  and  FIG. 2A   
         FIG. 3  is a perspective view of a first side of an embodiment of a tripolar electrode device including a flexible structure; 
         FIG. 4A  is a perspective view of an opposite side of the embodiment of  FIG. 3 ; 
         FIG. 4B  is a perspective view of an embodiment of a bipolar electrode device including a flexible structure similar to  FIG. 3  and  FIG. 4A ; 
         FIG. 5  is a perspective view of an embodiment of an extravascular Venus FlyTrap electrode device; 
         FIG. 6  is a perspective view of an embodiment of an extravascular Venus FlyTrap electrode device; 
         FIG. 7  is a perspective view of an embodiment of an intravascular Venus FlyTrap electrode device; 
         FIG. 8A  is a perspective view of an embodiment of an extravascular bipolar electrode device including a flexible structure similar to  FIG. 4B ; and 
         FIG. 8B  is a perspective view of components of the embodiment of  FIG. 8A . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is related to embodiments of extravascular and intravascular neural interface devices containing electrodes for neurostimulation of a target vessel. The devices may be housed in flexible substrates, each substrate having a central portion through which conductors for the electrodes are routed and housed. Extending from the central portion are a plurality of curvilinear flaps or arms that support the electrodes and position the electrodes to either be inward facing, i.e., extravascular designs, or outward facing, i.e., intravascular designs. An extravascular neural interface device is configured to be positioned outside of the target vessel, while an intravascular neural interface device is configured to be positioned at least partially within the target vessel. The substrate flaps or arms may include one or more electrodes and be configured to place one or more of the electrodes at specific positions relative to the target vessel. 
     An embodiment of a bi-polar, extravascular neural interface in accordance with the present disclosure is illustrated in  FIGS. 1 and 2A . The neural interface  100  may comprise a hybrid cuff, including a partially-helically formed supporting substrate  102 , manufactured of silicone or a similar flexible substance, such as styrene isoprene butadiene (SIBS), polyamide, parylene, liquid-crystal polymer (LCP), polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), fluorinated ethylene propylene (FEP), ethylene-tetrafluoroethylene (ETFE), polyurethane, or another biocompatible polymer, Biocompatible silicone and some other grades of silicone can be very flexible and soft, thereby minimizing mechanical mismatches between a cuff and a target vessel and minimizing constriction on the target vessel. Polymer materials may also be used, but those materials may be stiffer and harder than silicones and may require thinner material to be used, which may be both an advantage and a drawback. 
     The substrate  102  may include two C-ring portions  104  and  106 , each connected by a spinal portion forming a helix of one turn (when combined with a center portion  109  and one of the portions  104  or  106 ) in the opposite direction from a common center section  108  of a central portion  109 , and ending in an C-ring configuration where the C-ring is substantially orthogonal to the target vessel once positioned. Arranged within each C-ring end portion  104  and  106  may be multiple platinum or platinum alloy electrodes (or electrode arrays), such as electrode arrays  112  and  114 , versus multiple helical structures as in conventional systems. The electrodes arrays  112  and  114  may be of a conventional type and wired to a controller through conventional conductors  118 , such as 35N LT® DFT (Drawn Filled Tubing) with a 28% Ag core, in a stranded cable configuration (i.e., 7×7 configuration—not shown), or in a multi-filar coil configuration. The conductors are housed in a spine or spinal portion  120  that is affixed to end portion  106  and part of central portion  109 . 
     The configuration of the neural interface  100  may make it possible to significantly shorten the length of the neural interface  100 , thereby reducing the portion of target vessel or nerve that needs to be mobilized during placement. In addition, the opposing helical directions of the portions  104  and  106 , which each have a low helix angle relative to the spinal portion  120  may allow the neural interface  100  to be deployed and wound around the target vessel in one pass instead of at least two, as with conventional helical structures. A low helix angle or low pitch may allow the length of the neural interface  100  (or its distal end) to be shorter, which may result in less dissection of tissue during positioning. 
     The substrate  102  may include a number of attributions  110  placed at different points on or in the substrate  102 . The attribution may be configured to enable a deployment tool (not shown) to grip, manipulate and deploy the neural interface  100 . Thus, each attribution may be referred to as a deployment feature. The attributions may be protrusions. One or more protrusions may include one or more openings or eyelets for receiving a stylet (made of tungsten or similar material), for instance, in order to enable portions of the substrate to be straightened and/or to deploy the neural interface. The attributions  110  may also be openings, eyelets or some other form of lumen that may be equally manipulated by a deployment tool. 
     In an embodiment, the attributions  110  may be placed sufficiently near the open ends of the C-rings of portions  104  and  106  and near the end of center section  108  to enable the deployment tool to grip the attributions and simultaneously open the portions  104  and  108  and the center section  108  so that the neural interface may be positioned around the target vessel (not shown). As referred to herein, “open ends” refer to the ends positioned around the circumference of the C-rings, which are not attached to another feature (e.g., another C-ring or a spinal portion). In other words, each one of the “open ends” forms a side of a gap for the target vessel. Similarly “closed ends” refer to ends positioned around the circumference of the C-rings which are attached to another feature. In other words, each one of the “closed ends” does not form a gap for the target vessel. Once the neural interface  100  has been positioned around the target vessel, the deployment tool would carefully release the attributions so that the portions  104  and  108  and the center section  108  may softly self-size to the target vessel. By “self-size” it is meant that the neural interface  100  conforms to the shape of the target vessel of its own accord. 
     Another embodiment of a neural interface  200 , similar in structure to the embodiment illustrated in  FIGS. 1 and 2A , i.e., with multiple C-rings, a common center section, and forming two helical turns over a short length, is illustrated in  FIG. 2B . Neural interface  200  may be multipolar instead of bipolar as may be the case with neural interface  100 . In neural interface  200 , the substrate  202  may include three C-ring portions  204 ,  206  and  208 , with each C-ring end portion  204  and  206  connected by a one turn helix in the opposite direction from a common center section of an C-ring central portion  208 , and ending in C-ring configurations that may be orthogonal to the target vessel once positioned on the target vessel. C-ring central portion  208  may also be orthogonal to the target vessel. Positioned within each C-ring portion  204 ,  206  and  208  may be multiple platinum or platinum alloy electrodes (or electrode arrays), such as electrode arrays  212 ,  214  and  224 , fashioned (arranged) in such a way that electrodes in one C-ring covers the gap (along a length between electrodes) in the adjacent C-ring. Each electrode array is connected to a different conductor of the multi-conductor  218  housed in spinal portion  220 , which is affixed to just central portion  208 . The substrate  202  of neural interface  200  may not include attributions. Connecting individual electrodes or different arrays of electrodes to different conductors may enable selective stimulation of the target vessel by individually controlling each connected device. 
       FIGS. 3 and 4A  illustrate an embodiment of a tripolar neural interface  300  in accordance with the present disclosure. The neural interface  300  may be similar to neural interface  100  in that it may be formed of a flexible substrate  302  of similar material and may have two end portions  304  and  306  forming C-ring configurations that may be affixed to a spinal portion  308 . However, unlike neural interface  100 , the two end portions  304  and  306  may also not be connected to the center section. Instead, a center portion  330  forming a third C-ring may be utilized. The end portions  304  and  306  and the center portion  330  may have a very low helix angle, i.e., pitch, relative to the spinal portion  308 , which enables the neural interface to be helical, but still have a significantly shorter length. The helix angle may be between approximately 15 and 30 degrees, but may also be less than 15 degrees. 
     As with neural interface  100 , each of the C-rings of the neural interface  300  may include one or more electrodes or an array of electrodes, such as  312 ,  314  and  316 , each connected to a conductor  318  through the spinal portion  308 . A one electrode design may make it possible to maximize electrode coverage while minimizing the conductor interconnection process, such as through laser welding, resistance welding, etc. However, to minimize the rigidity of the electrode, i.e., making it sufficiently flexible, the electrode may have to be very thin (typically between 25 um and 50 um), which may make the interconnection of the conductors to the electrodes more challenging. Also, to keep the electrode as flexible as possible, surface features may not be possible to add to the electrode as it would decrease the electrode flexibility. For this reason, a one electrode may feature recessed electrodes with silicone rims or silicone webbing that may serve to hold the electrode in place. However, recessing the electrode may potentially decrease the efficacy of the stimulation. On the other hand, “segmented” electrode designs may provide better mechanical compliance, create the possibility of surface features, i.e., protruding electrodes, and make it possible to control each electrode individually (i.e., current steering). The trade-offs include limited electrode coverage, increased interconnection processes, decreased retention force. Segmented electrodes provide increased flexibility to the neural interface, thereby making it possible open a C-ring with a deployment tool wider and for a longer period of time, without creating excessive stress on the electrodes, than might be possible with a single electrode. 
     As shown in  FIGS. 2A and 4A , the individual electrodes of the electrode arrays  112  and  114  of neural interface  100  and electrode arrays  312 ,  314  and  316  of neural interface  300  may be evenly spaced within the substrates  102  and  302 , respectively. By evenly spacing the electrodes within the substrates, the inter-electrode distance is more constant, which may provide a more uniform current density distribution and enhancement of the effectiveness of the neural interfaces. In some embodiments, the position of the electrodes in the arrays may be staggered in order to achieve better electrical coverage. Certain characteristics of the neural interfaces  100  and/or  300 , such as, with respect to neural interface  300 , the spacing  350  between the electrode arrays  312 ,  314  and  316 , the size and shape of the electrodes, the size and shape and number of electrodes in electrode arrays, the inter-electrode distance within electrode arrays, and the angle of the helix angle, may each be chosen for the particular application of the neural interface. For example, utilization of the neural interface for treatment of the splenic artery may require different characteristics than utilization of the neural interface for treatment of a different vessel. For instance, when utilized for splenic artery treatment an electrode width of approximately 1-4 mm, with preferred width ranges of between approximately 1-2 mm and approximately 2-3 mm, may be appropriate. When utilized for treatment of different vessels, different electrode widths may be desirable. 
     The neural interface  300  may also include at least one attribution  310  that may be positioned on the outer surface of the substrate  302  near the open ends of each C-ring of the portions  304 ,  306  and  330 . As noted above, the attributions may include one or more openings or eyelets for receiving a stylet (made of tungsten or similar material), for instance, in order to enable portions of the substrate to be straightened and/or to deploy the neural interface. The attributions  310  may be configured to enable a deployment tool (not shown) to grip, manipulate and deploy the neural interface  300 . In an embodiment, the attributions  310  may be placed sufficiently near the open ends of the C-rings of portions  304 ,  306  and  330  to enable the deployment tool to grip the attributions  310  and simultaneously open the portions  304 ,  308  and  330  so that the neural interface  300  may be positioned around the target vessel (not shown). Once the neural interface  300  has been positioned around the target vessel, the deployment tool would carefully release the attributions so that the portions  304 ,  308  and  330  may softly self-size to the target vessel. The configuration of the neural interfaces  100  and  300  may enable the neural interfaces to be positioned in a single pass around the nerve/vessel with minimal manipulation of the nerve/vessel and a reduction in tissue dissection around the area of the nerve/vessel where the interface is positioned. 
     The neural interface  400  in  FIG. 4B  is similar to the neural interface  300 . Neural interface  400  is formed of a flexible substrate  402  of similar material and may have two end portions  404  and  406  forming C-ring configurations containing electrode arrays  412  and  414 . A center portion  430  may be affixed to a spinal portion  408  along with end portions  404  and  406 . The center portion  430  may not include any electrodes, serving just to retain the neural interface once positioned, but embodiments may include electrodes. 
     The neural interfaces  100 ,  200 ,  300  and  400  may be self-sizing; meaning that they may be formed of flexible materials that allow them to be manipulated for deployment, but when released return to a predetermined shape, much like a nitinol cage can be reduced down to fit in a catheter and return to its pre-reduced shape once released from the catheter. This may enable the neural interfaces to be used to accommodate anatomical variability of the intervention site, yet still provide good electrical contact between the electrode arrays and the surface of the nerve/vessel, thereby improving the efficient of the interface. The flexible material of the interface may remain compliant even when it has self-sized to a nerve or vessel. This may help to prevent the neural interface from compressing a nerve or vessel and causing reduced blood flow and otherwise constricting nerve fiber. This may also better accommodate radial expansion of the nerve/vessel as a result of post-positioning edema or swelling and may accommodate the pulsatile behavior of intervention sites such as arteries. 
     The naturally open structure of the helix of the neural interfaces  100 ,  200 ,  300  and  400  may reduce coverage of the nerve/vessel periphery to promote more normal fluid and nutrient exchange with the intervention site and surrounding tissue. This may also help to minimize growth of connective tissue between the electrode nerve/vessel interfaces. The open structure of each neural interface is configured such that no end portion or center portion forms a closed circumscribed circular arc around the target vessel at any point along a length of the target vessel. In other words, no closed circle covering  360  degrees of an orthogonal portion of the target vessel&#39;s length is formed by the structure. This open unrestricted trench may serve to ensure that the target vessel may pulsate without constriction and that an initially swollen target vessel can return to a normal state over time without constriction of the target vessel when it is swollen and without losing electrode to target vessel contact when the target vessel is in its normal state. 
       FIGS. 5 and 6  illustrate an additional embodiment of a self-sizing extravascular neural interface  500 . The neural interface  500  may be shaped more like a Venus FlyTrap clasp, with a spinal portion  502  connected to a conduit  504  including conductors for the neural interface, and sets of matching portions  510 ,  512  and  514  extending from the spine  502 . The portions  510 ,  512  and  514  may be substantially orthogonal to the spinal portion  502 . Each of the end portions  510  and  512  and the center portion  514  may include an electrode or electrode array  520 ,  522  and  524 , respectively, facing inward so that there may be a good electrical contact between the electrodes and the exterior walls of the target vessel/nerve  530 , and allow the artery to pulsate more freely. As previously discussed, this open trench may relieve pressure on the nerves  532  in the target vessel  530  that are sandwiched between the arterial wall and the neural interface  500 . The spacing or channels between the portions  510 ,  512  and  514  may also provide space for the target vessel to pulse and for fluids and nutrients to get to the target vessel. 
     The electrode or electrode arrays  520 ,  522  and  524  may also be positioned at different locations within each of the portions  510 ,  512  and  514 . The number of electrodes and their placement with the electrode arrays may vary. As shown in  FIGS. 5 and 6 , electrode  520  of end portion  510  is positioned near the tip of the end portion  510 , electrode  522  of center portion  512  is positioned near the middle of the center portion  512 , and electrode  514  of end portion  514  is positioned near the connection point of the end portion  514  to the spinal portion  502 . Naturally, different positional configurations (i.e., all electrodes at the tips, middle or spine of the portions, or any other combination of positions) may be possible and particularly selected to provide different circumferential coverage for the type of nerve/vessel and the treatment to be implemented. 
     As with the neural interface  100  and  300  described above, neural interface  500  is also self-sizing, in that the shapes of the portions  510 ,  512  and  514  are designed to substantially fit around most of the exterior circumference of the target vessel and the ribs are biased to a relaxed position that will cause them to wrap around most of the target vessel on their own accord once deployed. As used herein, the word “substantially” does not exclude “completely” e.g., a composition which is “substantially free” from Y may be completely free from Y. Where necessary, the word “substantially” may be omitted from the definition of the disclosure. For example, a substantially full turn of a helix may be a full turn of a helix, features positioned substantially opposite may be placed opposite, features spaced a substantially constant distance apart may be spaced a constant distance apart, and electrodes providing a substantially uniform current density may provide a uniform current density. 
     The portions  510 ,  512  and  514  may be orthogonal to the spinal portion  502  or at a low helix angel relative the spinal portion  502 . The composition of the substrate for the neural interface  500 , like neural interfaces  100  and  300 , can be silicon or a similar material, and all such neural interfaces can be further treated to prevent early scar formation (i.e., fibrous tissue). Such treatment may be done only on selected surfaces, e.g., the side facing the nerve/arterial wall. For example, silicon may be doped with a steroid drug, such as dexamethasone. The outer surface of the substrate of the neural interface may also, or alternatively, be coated with a hydrophilic polymer, such as poly-2-hydroeyethyl-methacrylate (pHEMA). 
     The tips of each portion  510 ,  512 , and  514  may be shaped to enable the portions to be griped by a deployment tool (not shown) for each placement on or removal from a target vessel and/or nerve. Alternatively, attributions, such as attributions  110  and  310  may be added to the exterior surface of the portions  510 ,  512  and  514  to enable the portions to be pulled back for placement on or removal from a target vessel and released when the neural interface  500  . 
       FIG. 7  illustrates an embodiment of a self-sizing intravascular neural interface  700 . As with neural interface  500 , neural interface  700  may be shaped like a Venus FlyTrap clasp, with a spinal portion  702  connected to a conduit  704  including conductors for the neural interface, and sets of matching portions  710 ,  712  and  714  extending from the spinal portion  702 . However, in contrast to neural interface  500 , each of the portions  710 ,  712  and  714  may include an electrode or electrode array  720 ,  722  and  724 , respectively, facing outward so that there may be a good electrical contact between the electrodes and the interior walls of the target vessel/nerve  730 , and allow the artery to pulsate more freely, which may relieve pressure on the nerves  732  in the target vessel  730  that are sandwiched between the interior arterial wall and the neural interface  700 . The spacing or channels (low-pressure trench) between the portions  710 ,  712  and  714  may also provide space for the target vessel to pulse and unrestricted conduit for fluids and nutrients to get to the interior walls of the target vessel  730 , while at the same time, not fully encircling the artery at any point of the cuff geometry. For example, with respect to each embodiment disclosed herein, no portion of the cuff geometry covers a circumference (a complete  360  degree rotation) of a portion of the target vessel orthogonal to any point on the spinal portion. 
     The electrode or electrode arrays  720 ,  722  and  724  may also be positioned at different locations within each of the portions  710 ,  712  and  714 . As shown in  FIG. 7 , electrode  720  of end portion  710  is positioned near the connection point between the spinal portion  702  and the end portion  710 , electrode  722  of center portion  712  is positioned near the middle of the center portion  712 , and electrode  714  of end portion  714  is also positioned near the spinal portion  702 . Naturally, different positional configurations (i.e., all at the tips, middle or spine, or any other combination of positions) may be possible and particularly selected for the range of the circumferential coverage of the nerve/vessel, for the type of nerve/vessel, and for the treatment to be implemented. 
     In contrast to the extravascular neural interfaces embodiments described above, neural interface  700  may be positioned via a flexible/collapsible catheter (with the neural interface  700  collapsed inside the catheter, not shown) versus an external deployment tools. Depending on the location of the target vessel, the positioning procedure may be minimally invasive. For example, for positioning in a splenic artery, the procedure may be performed through a total percutaneous access via standard (e.g., femoral) artery access. Once the catheter is positioned for deployment of the neural interface  700 , the catheter may be withdrawn and the released neural interface will self-size to the inside of the target vessel  730 , which requires the portions  710 ,  712  and  714  to be formed so their normal relaxed position will cause them to fold away from the spine  702  so as to make good contact with the interior walls of the target vessel  730 . 
     In the embodiment of  FIG. 8A , an extravascular bipolar electrode neural interface  800  is illustrated. The interface  800  includes a flexible structure similar to that of  FIG. 4B . In  FIG. 8B , the neural interface  800  of  FIG. 8A  is also depicted, but without a flexible substrate  802  and covering for the spinal portion  808 , which serves to further illustrate internal components of the neural interface  800  and a deployment tool. The neural interface  800  is similar to the neural interface  400  in  FIG. 4B . The flexible substrate  802  may be formed of material similar to that disclosed for neural interface  400 . The neural interface  800  may include two arms at either end of the device, such as end portions  804  and  806 , which may have open ends  805  and  807 , respectively. The end portions  804  and  806  may each be in a C-ring configuration and contain electrode arrays, such as arrays  812  and  814  of  FIG. 8B . A center arm portion  830  may be affixed to a spinal portion  808 , as are the closed ends of end portions  804  and  806 . The center portion  830  may not include any electrodes, serving just to retain the neural interface once positioned, but embodiments may include electrodes. 
     As shown in  FIG. 8B , the four electrodes  815  of each array  812  and  814  are connected in series via three microcoil interconnects  817 , which are in turn serially connected to a conductor  818 , for array  814 , and conductor  819 , for array  812 . The conductors  818  and  819  may be covered with the same flexible substrate material used to cover the end portions  804  and  806  and central portion  830  over the length of the spinal portion  808  and extending for a short distance from the neural interface  800 , Before the conductors  818  and  819  exit the material of the spinal portion they are also covered with a silicon lead body tubing  820  to form the lead body conductor  822 . 
     As previously noted, attributions may be protrusions, but may also be openings or eyelets. As illustrated in  FIG. 8A , the attributions may be openings  840  formed at the open end  805  and  807  of end portions  804  and  806 . The deployment tool  841  may be comprised of suture wire  842 , grab tab tubing  844 , a connector  846  and a grab tube loop  848 . The suture wire  842  may be looped through each opening  840  and through the silicon tubing of grab tab  844 . The suture wire  842  may then be brought together at connector  846  to form a grab tube loop  848 . During deployment of the neural interface  800 , a surgeon may position the central portion  830  around a target vessel (not shown in  FIGS. 8A and 8B ), while pulling lightly on the grab tube loop  848 . Such pressure will pull the open ends  805  and  807  of end portions  804  and  806  away from the spinal portion  808  and make it possible to position the neural interface  800 . 
     When the neural interface  800  is properly positioned, the pressure may be removed from the grab tube loop  848  so that the open ends  805  and  807  may softly self-size around the target vessel. Although not shown in  FIGS. 8A and 8B , the central portion  830  may also include an opening attribution  840  so it may be opened in a similar manner to end portions  804  and  806  for self-sizing around the target vessel. Once the neural interface has been properly positioned, the suture wire  842  may be cut and removed from the openings  840 . The opening attributions  840  may be circular holes, oval-shaped slots (not shown in  FIGS. 8A and 8B ) or other shapes, or eyelets (not shown in  FIGS. 8A and 8B ) that extend on tabs from the end portions  805  and  807 . 
     The following is a non-exhaustive list of embodiments that may or may not be claimed:
     1. A neural interface, comprising:   

     a first end portion, a second end portion and a center portion positioned between the first end portion and the second end portion, wherein the first end portion includes at least a first electrode and the second end portion includes at least a second electrode, wherein the first end portion, the second end portion and the center portion are formed of a flexible material that is configured to enable each of the first end portion, the second end portion and the center portion to self-size to a surface of a target vessel when the neural interface is released at a position along the target vessel, and wherein neither the first end portion, the second end portion nor the center portion form a closed circumscribed circular arc around the target vessel at any point along a length of the target vessel; and 
     a spinal portion configured to house electrical conductors for the first electrode and the second electrode, the spinal portion being connected to one or more of the first end portion, the center portion and the second end portion.
     2. The neural interface of embodiment 1, wherein the first electrode is positioned toward a surface of the first end portion adjacent to an exterior surface of the target vessel, wherein the second electrode is positioned toward a surface of the second end portion adjacent to the exterior surface of the target vessel, and wherein the neural interface is extravascular.   3. The neural interface of embodiment 2, wherein the first end portion, the second end portion and the center portion each a semi-circular arc around the target vessel with at least one open end, wherein the first end portion, the second end portion and the center portion each include a deployment lumen positioned near the one open end, wherein each deployment lumen is configured to be griped by a deployment tool and pulled back to open each semi-circular arc and enable the first end portion, the second end portion and the center portion to be placed on the target vessel, and wherein the flexible material is biased to enable the first end portion, the second end portion and the center portion to self-size to fit around the target vessel when the deployment tool releases each deployment lumen.   4. The neural interface of embodiment 2, wherein the first end portion and the second end portion each form a semi-circular arc around the target vqessel with two open ends, wherein the center portion forms a semi-circular arc around the target vessel with one open end, a first closed end and a second closed end, wherein the first closed end is attached to the first end portion at a first point and the second closed end is attached to the second end portion at a second point, wherein a first section of the center portion between the first point and the open end forms a substantially full turn of a first helix, and wherein a second section of the center portion between the second point and the open end forms a substantially full turn of a second helix.   5. The neural interface of embodiment 4, wherein the first end portion and the second end portion each include a deployment lumen positioned near the open ends and the center portion includes a deployment lumen positioned near the one open end, wherein each deployment lumen is configured to be griped by a deployment tool and pulled back to open each semi-circular arc and enable the first end portion, the second end portion and the center portion to be placed on the target vessel, and wherein the flexible material is biased to enable the first end portion, the second end portion and the center portion to self-size to fit around the target vessel when the deployment tool releases each deployment lumen.   6. The neural interface of embodiment 2, wherein the first end portion, the second end portion and the center portion each form a semi-circular arc around the target vessel with one open end and one closed end, wherein each of the one closed end is attached to the spinal portion, wherein the center portion includes at least a third electrode attached to an electrical conductor housed by the spinal portion, and wherein the third electrode is positioned toward an interior surface of the center portion.   7. The neural interface of embodiment 6, wherein the first end portion, the second end portion and the center portion each include a deployment lumen positioned near the open end, wherein each deployment lumen is configured to be griped by a deployment tool and pulled back to open each semi-circular arc and enable the first end portion, the second end portion and the center portion to be placed on the target vessel, and wherein the flexible material is biased to enable the first end portion, the second end portion and the center portion to self-size around the target vessel when the deployment tool releases each deployment lumen.   8. The neural interface of embodiment 1, wherein the first end portion, the second end portion and the center portion are formed from two substantially opposing semi-circular arcs, wherein each semi-circular arc includes a closed end attached to the spinal portion and an open end, wherein an opening is formed between the open end of each semi-circular arc substantially opposite the spinal portion, wherein the center portion includes at least a third electrode attached to an electrical conductor housed by the spinal portion, wherein the third electrode is positioned toward an interior surface of the center portion.   9. The neural interface of embodiment 8, wherein each open end of each semi-circular arc is configured to be griped by a deployment tool and pulled back to further open each semi-circular arc and enable the first end portion, the second end portion and the center portion to be placed on the target vessel, and wherein the flexible material is biased to enable the first end portion, the second end portion and the center portion to self-size to fit around the target vessel when the deployment tool releases each open end.   10. The neural interface of embodiment 8, wherein each semi-circular arc includes at least one electrodesax positioned substantially opposite the at least one electrode of an opposing semi-circular arc thereby forming a pair of electrodes.   11. The neural interface of embodiment 10, wherein each pair of electrodes is positioned near the open end of each semi-circular arc, near the closed end of each semi-circular arc, or in-between the open end and the closed end of each semi-circular arc.   12. The neural interface of embodiment 1, wherein the first electrode is positioned toward an exterior surface of the first end portion, wherein the second electrode is positioned toward an exterior surface of the second end portion, wherein the neural interface is intravascular, wherein the first end portion, the second end portion and the center portion are formed from two substantial opposing semi-circular arcs, wherein each semi-circular arc includes a closed end attached to the spinal portion and an open end, wherein an opening is formed between the open end of each semi-circular arc substantially opposite the spinal portion, wherein the center portion includes at least a third electrode attached to an electrical conductor housed by the spinal portion, wherein the third electrode is positioned toward an exterior surface of the center portion.   13. The neural interface of embodiment 12, wherein the first end portion, the second end portion and the center portion are configurable to be placed inside a catheter for positioning within the target vessel, and wherein the flexible material is biased to enable the first end portion, the second end portion and the center portion to self-size to fit against interior walls of the target vessel when released from the catheter.   14. The neural interface of embodiment 12, wherein each semi-circular arc includes at least one electrode positioned substantially opposite the at least one electrode of an opposing semi-circular arc thereby forming a pair of electrodes.   15. The neural interface of embodiment 14, wherein each pair of electrodes is positioned near the open end of each semi-circular arc, near the closed end of each semi-circular arc, or in-between the open end and the closed end of each semi-circular arc.   16. The neural interface of embodiment 1, wherein the first electrode and the second electrode are electrode arrays including a plurality of inter-electrodes, wherein each inter-electrode is spaced a substantially constant distance from an adjacent inter-electrode to provide a substantially uniform current density.   17. The neural interface of embodiment 1, wherein the material is a silicon-based material.   18. The neural interface of embodiment 17, wherein the silicon-based material is doped with a steroid drug.   19. The neural interface of embodiment 17, wherein the silicon-based material is coated with a hydrophilic polymer.   20. The neural interface of embodiment 1, wherein the first end portion, the second end portion and the center portion are each separated sufficiently to allow radial expansion and contraction of the target vessel without compressing nerves in the target vessel or reducing blood flow or fluid exchange with tissue of the target vessel.   21. The neural interface of embodiment 1, wherein the first electrode and the second electrode are single electrodes embedded in the flexible material.   22. The neural interface of embodiment 21, wherein the center portion includes a third electrode, wherein the third electrode is a single electrode embedded in the flexible material.   23. The neural interface of embodiment 1, wherein the first electrode and the second electrode are electrode arrays each having a plurality of individual electrodes, and wherein each individual electrode protrudes from the flexible material.   24. The neural interface of embodiment 23, wherein the center portion includes a third electrode array, and wherein each individual electrode protrudes from the flexible material.   25. The neural interface of embodiment 1, wherein the center portion is connected to the first end portion by a first spiral section and the center portion is connect to the second end portion by a second spiral section, wherein the center portion, the first spiral section and the first end portion are configured to complete a first helical turn around the target vessel in a first direction when the neural interface is positioned on the target vessel, wherein the center portion, the second spiral section and the second end portion are configured to complete a second helical turn around the target vessel in a second direction opposite the first direction when the neural interface is positioned on the target vessel.   26. The neural interface of embodiment 25, wherein a helix angle of the first helical turn and the second helical turn is less than 15 degrees.   27. The neural interface of embodiment 1, wherein the first electrode and the second electrode have a width of between 1 mm and 4 mm.   28. The neural interface of embodiment 1, wherein at least the first end portion is formed from a substantially opposing semi-circular arc, wherein the semi-circular arc includes a closed end attached to the spinal portion and an open end, wherein an opening is formed between the open end of the semi-circular arc substantially opposite the spinal portion, wherein the open end includes an attribution configured to engage a deployment tool, wherein application of pulling pressure on the deployment tool pulls the open end of the first end portion away from the spinal portion and enables the first end portion to be positioned around the target vessel, and wherein removal of the pulling pressure allows the first end portion to self-size to the surface of the target vessel.   29. The neural interface of embodiment 28, wherein the attribution is a protrusion.   30. The neural interface of embodiment 28, wherein the attribution is an opening formed in the flexible material.   31. The neural interface of embodiment 30, wherein the opening is configured to be engaged by suture wire of the deployment tool.   32. The neural interface of embodiment 1, wherein the first end portion and the second end portion are each formed from substantially opposing semi-circular arcs, wherein each semi-circular arc includes a closed end attached to the spinal portion and an open end, wherein an opening is formed between the open end of the semi-circular arc substantially opposite the spinal portion, wherein the open end includes an attribution configured to engage a deployment tool, further comprising a deployment tool configured to engage each attribution, wherein application of pulling pressure on the deployment tool pulls each open end away from the spinal portion and enables the first end portion and the second portion to be positioned around the target vessel, and wherein removal of the pulling pressure allows the first end portion and the second portion to self-size to the surface of the target vessel.   33. The neural interface of embodiment 1, wherein the attribution is an opening formed in the flexible material, wherein the deployment tool includes suture wire looped through each opening.   34. The neural interface of embodiment 33, wherein the deployment tool further includes a grab tab configured to enable a surgeon to apply the pulling pressure.   35. The neural interface of embodiment 34, wherein the grab tab includes silicone tubing through which the suture wire passes between the opening and a loop formed by the suture wire.   

     The embodiments of the present disclosure, while illustrated and described in terms of various embodiments, is not limited to the particular description contained in this specification. Additional alternative or equivalent components and elements may be readily used to practice the present disclosure.