Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Reexamination Certificate
1999-06-14
2001-01-16
Kamm, William E. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
Reexamination Certificate
active
06175769
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a device used in the treatment of neurological disorders, especially pain and motor dysfunction by electro-stimulation of the spinal cord, and more particularly to a novel electrode having integrally formed attachment means which permit more reliable positioning of the electrode relative to the spinal cord.
2. Description of the Prior Art
The use of electrical stimulation for the purposes of alleviating pain and the treatment of other neurological afflictions has been utilized for a number of years, and in many instances has become the standard of care. In new applications, as well, electrical stimulation of components of the nervous system continues to show significant therapeutic promise.
More particularly, in the spine, the original approach to electrical stimulation was to place multiple electrical leads directly onto the dura around the spinal cord. In such a procedure, the larninae of a sequence of vertebrae were removed so that the leads could be placed in a spaced apart relation along the central posterior axis of the spinal cord. This approach required a substantially invasive procedure in which bones and tissue were displaced or removed. In addition, the high frequencies of electrode migration from the target site or sites rendered the entire procedure suspect.
Subsequent iterations of spinal cord stimulation devices were implanted much less invasively, generally by percutaneous positioning. The first generations of this approach were immediately advantageous over the prior methods, insofar as they were carried out using local anesthetic as the electrodes were guided into position with the use of a fluoroscope. These early non-invasive procedures continued to use single lead electrodes, thus requiring a plurality of separate implantations. In addition, the leads would still easily become dislodged and migrate from the desired treatment site, usually becoming ineffective, but sometimes having actively negative effects on other nerves. These limitations and failures associated with multiple implantations of single lead electrodes briefly caused a reversion to the older, more invasive approach.
In an attempt to unify the multiple leads necessary for spinal cord stimulation into a single electrode, thereby attempting to bring the state of the art back to non-invasive procedures, designs from the cardiovascular art, i.e. pacemakers, et al., were modified for use in the spine. Multiple lead electrodes had been used in the cardiovascular field for some time, and were generally designed to provide stimulation to a variety of points on the surface of the heart. The modifications of these leads included strengthening the both the leads and the structure containing the leads for the stresses of the spine, reducing the diameter of the leads to a size more appropriate for use in the spine, and alternatively providing either a removeable or permanent rigid wire within the electrode to enhance placement. Unfortunately, while eliminating some of the causes associated with electrode migration, and reducing the number of electrodes which could migrate, the advances did not address the fundamental inability to fix the electrode at the appropriate location.
Subsequent limited attempts to identify ways to stabilize the electrode at a specific location in the spine have been limited to integrating a fabric material into the terminal pad portion of the electrode, which fabric extends laterally out from the elastomeric pad portion, through which the surgeon may suture the electrode to the surrounding tissue. Unfortunately, surgeons generally prefer to suture through the more substantial elastomeric material of the terminal pad, thereby risking damaging the electrical contacts and leads therein.
Accordingly, it is an object of the present invention to provide a spinal cord stimulator assembly which reduces the incidence and complications associated with the migration of the electrode.
Correspondingly, it is also an object of the present invention to provide a spinal cord stimulator assembly which permits attachment of the electrode to surrounding soft tissue while minimizing the risk of inadvertent damage to the electrical contacts and thin wire leads of the device.
SUMMARY OF THE INVENTION
The preceding expressed object is provided in the present invention, which comprises new and novel embodiments of electrode and vertebral attachment devices for use in spinal cord stimulation, and which may be used in conjunction with standard and/or advanced electrical signal sources. More particularly, a variety of different embodiments of the present invention are contemplated, preferred ones of which are disclosed herein, including electrode assemblies having terminal pads which comprise laterally extending elastomeric material which does not include any electrically active materials, and which is ideal for receiving a suture, therethrough. These laterally extending suture receiving portions may further be color coded by the inclusion of a readily discernable dye by which the surgeon may easily recognize the safe portions of the terminal pad through which he may suture. These laterally extending suture pads may further (or alternatively) include small through holes which the surgeon may insert guidewires or other fastening devices for anchoring the electrode to surrounding bony tissue through which the surgeon would not otherwise be able to suture.
The electrode designs of the present invention have some similar features to those of the prior art, and more particularly, they each comprises a plurality of thin wire leads which are encased within a flexible elastomeric sheath. The wire leads may be wound in a tight helix in the elastomeric sheath so that the structure remains flexible in the axial as well as transverse directions. In addition, the wound structure may permit the inclusion of a selectively removeable rigid wire backbone by which the surgeon may manipulate the electrode into proper position. Each of said wire leads is coupled to a corresponding individual electrical contact located at the proximal end of the sheath. These contacts are coupled to the electrical signal generator which provides the potential to the distal tip which is placed adjacent to the spinal cord (or other target nerve group).
More particularly, the distal end of the electrode comprises a series of electrical terminals, generally equivalent in number to the number of electrical contacts at the proximal end (one terminal at the distal end and one electrical contact in the proximal end are preferably individually coupled to one another by one wire lead, each coupled set being in electrical isolation with the other sets so that each may carry a different potential). The terminals and the portion of the elastomeric sheath which contains them may be cylindrical (as is the rest of the sheath), however, it is preferred in the present invention that it be flattened out, forming a planar pad structure. The planar terminal pad generally includes a series of individual terminals which are generally circular and planar. As suggested above, the terminal pads are spaced apart from one another so that they are in at least partial electrical isolation from one another. The application of a voltage differential across the pads (by the coupling of the corresponding electrical contacts to different, or variable, voltage sources) causes a current to flow through the adjacent tissue. This current causes the disruption of pain signals in the target nerve roots, thus alleviating pain.
The terminal pad portion of the present invention, and specifically the new and novel features thereof, include means for attaching the pad to surrounding tissue. More particularly, in a first embodiment, the terminal pad includes at least one laterally extending portion which is formed of the same elastomeric material as the sheath in which the wire leads are encased. This at least one laterally extending portion preferably includes multiple symmetric laterally extending
Errico Joseph P.
Errico Thomas J.
Electro Core Technologies, LLC
Errico, Esq. Joseph P.
Kamm William E.
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