Electrical stimulation system including a device for partially shielding electrical energy emitted from one or more electrical stimulation leads implanted in a human's body

In one embodiment, a device is provided for partially shielding electrical energy emitted from an electrical stimulation lead implanted in a human's body to enable stimulation of the human's nerve tissue, the lead including one or more electrodes operable to stimulate the nerve tissue. The device includes an anterior concave surface adapted to contact and at least partially surround a posterior side of the lead such that the lead is positioned between the anterior concave surface and the nerve tissue when the device and the lead are implanted in the body. The device includes a posterior convex surface coupled to the anterior concave surface and adapted to contact the body tissue opposite the nerve tissue. The device is adapted to partially shield electrical energy emitted from one or more electrodes on a posterior side of the lead when the device and the lead are implanted in the body to reduce a quantity of electrical energy reaching the body tissue opposite the nerve tissue.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to electrical stimulation systems designed for implantation into a human's body and more particularly to an electrical stimulation system including a device for partially shielding electrical energy emitted from one or more electrical stimulation leads implanted in a human's body.

BACKGROUND

Electrical energy is applied to the spinal cord and peripheral nerves to treat regions of the body that are affected by chronic pain from a variety of etiologies. One method of delivering electrical energy is to implant an electrode and position it in a precise location adjacent the spinal cord such that stimulation of the electrode causes a subjective sensation of numbness or tingling in the affected region of the body, known as “paresthesia.” Pain managing electrical energy is commonly delivered through electrodes positioned external to the dura layer surrounding the spinal cord. The electrodes may be carried by either of two primary vehicles: a percutaneous lead and a laminotomy or “paddle” lead.

Percutaneous leads commonly have three or more electrodes. They are positioned above the dura layer using a needle that is passed through the skin, between the desired vertebrae and onto the top of the dura. Percutaneous leads deliver energy radially in all directions because of the circumferential nature of the electrode. Percutaneous leads can be implanted using a minimally invasive technique. In a typical percutaneous lead placement, a trial stimulation procedure is performed to determine the optimal location for the lead. Here, a needle is placed through the skin and between the desired vertebrae. The percutaneous lead is then threaded through the needle into the desired location over the spinal cord dura. Percutaneous leads may also be positioned in other regions of the body near peripheral nerves for the same purpose.

Laminotomy or paddle leads have a paddle-like configuration and typically possess multiple electrodes arranged in one or more independent columns. Paddle leads provide a more focused energy delivery than percutaneous leads because electrodes may be present on only one surface of the lead. Paddle leads may be desirable in certain situations because they provide more direct stimulation to a specific surface and require less energy to produce a desired effect. Because paddle leads are larger than percutaneous leads, they have historically required surgical implantation through a procedure known as partial laminectomy that requires the resection and removal of vertebral tissue.

SUMMARY OF THE INVENTION

In one embodiment, a device is provided for partially shielding electrical energy emitted from an electrical stimulation lead implanted in a human's body to enable stimulation of the human's nerve tissue. The electrical stimulation lead includes one or more electrodes operable to stimulate the human's nerve tissue. The device includes an anterior concave surface adapted to contact and at least partially surround a posterior side of the electrical stimulation lead such that the electrical stimulation lead is positioned between the anterior concave surface of the device and the human's nerve tissue when the device and the electrical stimulation lead are implanted in the human's body. The device includes a posterior convex surface coupled to the anterior concave surface and adapted to contact the human's body tissue opposite the human's nerve tissue. The device is adapted to partially shield electrical energy emitted from one or more electrodes on a posterior side of the electrical stimulation lead when the device and the electrical stimulation lead are implanted in the human's body to reduce the quantity of electrical energy reaching the human's body tissue opposite the human's nerve tissue.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIGS. 1A-1Cillustrate perspective, cross-sectional, and side views of an example device10for partially shielding electrical energy emitted from an electrical stimulation lead12. For example, device10may be used to shield such electrical energy in a human who receives electrical stimulation treatment directed to the human's spinal nerve tissue, peripheral nerve tissue, or any other suitable target nerve tissue for pain management or other therapeutic purposes. Device10allows electrical stimulation of the target nerve tissue to occur while reducing the impact, if any, of such electrical stimulation on neighboring tissues. For example, where the target nerve tissue includes spinal nerve tissue such that electrical stimulation lead12and associated device10are implanted in the human's epidural space, device10may prevent at least some electrical energy from reaching the human's body tissue opposite the target nerve tissue such as the human's ligamentum flavum and associated tissue. Although device10may be used to partially shield electrical energy emitted from any type of electrical stimulation lead12, device10may be particularly useful as a shield with respect to a percutaneous electrical stimulation lead12having circumferential electrodes that emit electrical energy radially in all directions.

In one embodiment, device10includes an anterior concave surface14coupled to a posterior convex surface16. As used herein, the term “anterior” refers to the direction of the target nerve tissue to be stimulated and the term “posterior” refers to the direction of the body tissue opposite the target nerve tissue, regardless of true orientation within a human's body. For example, for electrical stimulation of spinal nerve tissue, anterior concave surface14of device10may face in a truly anterior direction with respect to the human's body, while for electrical stimulation of certain peripheral nerve tissue it may not. Anterior concave surface14is adapted to contact and at least partially surround a posterior side of electrical stimulation lead12. Lead12may seat loosely in device10or may “snap” into or otherwise be removably secured within device10. Posterior convex surface16is adapted to contact the human's body tissue opposite electrical stimulation lead12(i.e. proximate the ligamentum flavum in the case of electrical stimulation of spinal nerve tissue). In one embodiment, the interior of device10between anterior concave surface14and posterior convex surface16is solid rather than hollow, although device10may be formed with a hollow interior if appropriate.

As shown inFIG. 1C, a leading end20of device10may extend beyond and at least partially surround a corresponding leading end22of lead12such that, when lead12is pushed in the direction of leading ends20and22, device10is simultaneously pushed in the same direction and to the same extent. This may allow device10to be inserted more easily in association with lead12. Instead or in addition, leading end20of device10may be tapered to allow device10to be inserted more easily. A trailing end of device10may similarly extend beyond and at least partially surround a corresponding trailing end of lead12to allow device10to be withdrawn more easily in association with lead12. Instead or in addition, the trailing end of device10may be tapered to allow device10to be withdrawn more easily.

In one embodiment, upon insertion of device10into a region of a human's body such as the human's epidural space, device10may function as an anterior-posterior or other stabilizer for electrical stimulation lead12such that electrical stimulation lead12is not able to freely float within the human's epidural space. Stabilization of electrical stimulation lead12in the human's epidural space or other region of the body may be difficult without device10because it may be difficult to suture or otherwise fixate electrical stimulation lead12in position. Stabilization of electrical stimulation lead12in the human's epidural space or other region of the body may help improve performance, comfort, and overall treatment results.

Device10may be sized and shaped according to the type of target nerve tissue to be stimulated, the amount or type of electrical energy to be emitted from electrical stimulation lead12, the space available within the human's body for electrical stimulation lead12and associated device10, or any other suitable factors. In one embodiment, device10may be formed from material that is collapsible for easier removal from the human's epidural space or other region of the body. Instead or in addition, device10may be formed from material that is expandable such that it more completely fills the remaining epidural space or other region upon insertion and acts to buttress electrical stimulation lead12against the human's surrounding tissue for increased stability. Device10may be formed from material that is pliable enough to configure to the curvature of the human's epidural space or other region or to conform to any other suitable anatomical size or shape as necessary for insertion into the human's body. In one embodiment, for example, device10may be formed of polyurethane.

As shown inFIGS. 2A-2C, in other embodiments, device10may be configured to accommodate and shield electrical energy emitted from multiple electrical stimulation leads12according to particular needs. Although an example device10accommodating two leads12is shown, device10may be configured to accommodate any suitable number of leads12and the present invention is intended to encompass all such configurations. Device10may include one or more lobes24to separate adjacent leads12. Lobe24may help position and stabilize leads12and may further shield electrical energy emitted from leads12.

FIG. 3illustrates an example of device10implanted proximate electrical stimulation lead12in a human's epidural space30. In this example, electrodes32are circumferential electrodes located along the longitudinal axis of a percutaneous electrical stimulation lead12that emit electrical energy radially in all directions. Spinal cord34and ligamentum flavum36are also shown. Anterior concave surface14of device10partially surrounds a posterior side of electrical stimulation lead12. Electrical stimulation lead12is positioned between anterior concave surface14of device10and spinal cord34. Posterior convex surface16of device10is adapted to contact the human's body tissue proximate ligamentum flavum36. Device10functions as an electrical energy shield between electrical stimulation lead12and ligamentum flavum36and associated tissue. Device10may also function as a spacer to position electrical stimulation lead12within epidural space30closer to spinal cord34and to help secure electrical stimulation lead12in position.

Now referring toFIGS. 4A-4B, there are shown two embodiments of an electrical stimulation system200,300in accordance with the present invention. Stimulation system200,300generates and applies a stimulus to a human's nerve tissue or to certain locations of the human's body. In general terms, stimulation system200,300includes a stimulation or energy source210,310and an electrical stimulation lead110for application of the stimulus. Lead110shown inFIGS. 4A-4Bis lead12described above.

As shown inFIG. 4A, stimulation system200includes lead110coupled to stimulation source210. In one embodiment, stimulation source210includes an implantable pulse generator (IPG). As is known in the art, an IPG is implanted within the human's body that is to receive electrical stimulation from stimulation source210. An example IPG may be one manufactured by Advanced Neuromodulation Systems, Inc., such as the Genesis® System, part numbers 3604, 3608, 3609, and 3644.

As shown inFIG. 4B, stimulation system300includes lead110coupled to stimulation source310. Stimulation source310includes a wireless receiver. As is known in the art, stimulation source310comprising a wireless receiver is implanted within the human's body that is to receive electrical stimulation from stimulation source310. An example wireless receiver310may be those wireless receivers manufactured by Advanced Neuromodulation Systems, Inc., such as the Renew® System, part numbers 3408 and 3416.

The wireless receiver within stimulation source310is capable of receiving wireless signals from wireless transmitter320. The wireless signals are represented inFIG. 4Bby wireless link symbol330. Wireless transmitter320and controller340are located outside of the human's body that is to receive electrical stimulation from stimulation source310. A user of stimulation source310may use controller340to provide control signals for operation of stimulation source310. Controller340provides control signals to wireless transmitter320, wireless transmitter320transmits the control signals and power to a receiver in stimulation source310, and stimulation source310uses the control signals to vary the signal parameters of the electrical signals that are transmitted through lead110to the stimulation site. An example wireless transmitter320may be those transmitters manufactured by Advanced Neuromodulation Systems, Inc., such as the Renew® System, part numbers 3508 and 3516.

As will be appreciated, the connectors are not visible inFIGS. 4A-4Bbecause the contact electrodes are situated within a receptacle of stimulation source210,310. The connectors are in electrical contact with a generator of electrical signals within stimulation source210,310. Stimulation source210,310generates and sends electrical signals via lead110to electrodes160. Understandably, electrodes160are located at a stimulation site within the human's body that is to receive electrical stimulation from the electrical signals. A stimulation site may be, for example, adjacent one or more nerves in the central nervous system (e.g., spinal cord) or one or more peripheral nerves. Stimulation source210,310is capable of controlling the electrical signals by varying signal parameters (e.g., intensity, duration, frequency) in response to control signals that are provided to stimulation source210,310.

In one embodiment, lead110and associated device10are inserted into epidural space20or near a peripheral nerve using a suitable introducer. For example, lead110and associated device10may be inserted percutaneously using a needle according to standard techniques, as described more fully inFIG. 5A. As another example, lead110and associated device10may be inserted using an introducer having a hollow inner penetrator removably housed in a hollow outer sheath, as described more fully inFIG. 5B. Once lead110and device10have been inserted, lead110extends from the insertion site to the implant site. The implant site is typically a subcutaneous pocket that receives and houses the IPG or receiver (providing stimulation source210,310). The implant site is usually positioned a distance away from the stimulation site, such as near the buttocks or another place in the torso area. In many cases, the implant site and insertion site are located in the lower back area and lead110extends through epidural space20to the stimulation site (e.g., middle or upper back, neck, or brain areas). Once system200,300is implanted, the system of leads and/or extensions may be subject to mechanical forces and movement in response to body movement.FIGS. 5A-5Billustrate example steps that may be used to implant an example stimulation system200,300into a human for electrical stimulation of the human's spinal nerve tissue.

Although the present invention has been described with several embodiments, a number of changes, substitutions, variations, alterations, and modifications may be suggested to one skilled in the art, and it is intended that the invention encompass all such changes, substitutions, variations, alterations, and modifications as fall within the spirit and scope of the appended claims.