Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Patent
1997-03-18
1999-04-27
Getzow, Scott M.
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
A61N 105
Patent
active
058975837
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to a flexible and nonconductive, artificial, implantable nerve plate ("flexible nerve plate", or FNP) for placement or insertion between the fascicles of a nerve bundle.
In the field of neuroprosthetics, new possibilities are being sought to contact nerve bundles and nerve fibers as gently as possible to a multiplicity of electrodes in order to derive multilocal and simultaneous nerve signals and/or stimulate nerve fibers. In this manner, by utilization of technical aid systems, it should also be possible to restore failed bodily functions by registering nerve signals and by stimulating nerves in the peripheral nerve system.
Interfascicular derivation techniques are used to detect nerve signals within a fascicle. (A fascicle is an organizational unit of nerve fibers within a nerve bundle.) Interfascicular electrodes are single bipolar electrodes, which derive both the electrical potential in the nerve fascicle and the electric potential at the nerve surface thereby making a differential measurement possible, which largely eliminates the disturbances caused by electromagnetic interferences. The signals from the sensory touch nerves of the front paws of cats were recorded with implanted interfascicular electrodes. Furthermore, motor nerves were successfully stimulated by means of implanted interfascicular electrodes.
The time and work consumed for precise placement of the electrodes, however, is considerable. As wire electrodes, the electrodes are single channel. Although new multi-channel silicon embodiments are in development, neither single nor multi-channel embodiments are sufficiently suited for permanent implantation. Moreover, the perineurium (the membrane around the fascicles) is damaged when the electrodes are inserted.
Shaft electrodes especially developed for the needs of an intracortical implantation, i.e. an implantation penetrating the pachymenix of the cerebral cortex or transmural, intracardial implantation, are known from IEEE Transactions on Biomedical Engineering vol. 39, No. 3, 1992, p. 271-279 and No. 5, p. 474-481. Insertion of a 125 .mu.m thick Kapton foil between the fascicles in peripheral nerves is inconceivable, however, because the nerve is so badly degenerated, due to movement of the electrode as a consequence of muscle movement as well as due to the weight load and the momentary load on the nerve from the microelectrode as a result of gravity, that a derivation and simulation is not possible.
Kovacs has already demonstrated single-fiber contacting of proximal nerve stumps branching into meshlike microstructures. In order to aid the branching of the nerve stumps, a resection (removal of the fibrous-altered nerve section by cutting with a scalpel) must be conducted on the proximal stumps. This surgery does not seem suited for contacting large peripheral nerves (e.g. ischaeticus, n. femoralis) or for nerves without a total loss of continuity of function. Mesh electrodes are not suited for contacting healthy nerves, because free nerve endings are needed for branching through the mesh.
Since the 1970s, attempts have been made to stimulate and record neurograms with extraneural cuff-like electrodes, so-called cuff electrodes, which are placed encircling the nerve. Cuff electrodes have meanwhile become the most successful form of construction of biomedical electrodes and have found use in many fields. There are several U.S. patents for various forms of construction: for example, U.S. Pat. Nos. 3,774,618; 3,738,368; and 3,654,933. Some electrodes have been safely in use for 15 years. The number of electrodes is limited to three or four. Only a limited local resolution of the stimulation within the nerve can be achieved (tripolar electrodes). Drawback: multilocal stimulation (with more than four electrodes) of the nerve is only possible to a limited extent. Deeper structures can be achieved only with an increased stimulation current. Simultaneous stimulation and derivation is not possible.
One object of the present in
REFERENCES:
patent: 3654933 (1972-04-01), Hagfors
patent: 3738368 (1973-06-01), Avery et al.
patent: 3774618 (1973-11-01), Avery
Meyer Jorg-Uwe
Stieglitz Thomas
Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung
Getzow Scott M.
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