Method and apparatus for recording activity in intact nerves

• US 3,957,036 A
• Filed: 02/03/1975
• Issued: 05/18/1976
• Est. Priority Date: 02/03/1975
• Status: Expired due to Term

• Current Assignee: Baylor College of Medicine (Baylor College)
• Original Assignee: Baylor College of Medicine (Baylor College)
• Inventors: Normann, Nils A.
• Primary Examiner(s): Michell, Robert W.
• Assistant Examiner(s): Cohen, Lee S.
• Application Number:
  US05/546,228
• Time in Patent Office: 470 Days
• Field of Search: 128/2.1 E, 128/2.06 E, 128/DIG. 4, 128/418, 128/419 C, 128/419 E, 128/419 P, 128/2.1 R, 128/404, 128/405, 128/407-411, 128/416, 128/417
• US Class Current: 600/377
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/29 for permanent or long-term implantation
• CPC Class Codes: A61B 5/30 Input circuits therefor
• CPC Class Codes: A61B 5/308 for electrocardiography [ECG]

Abstract

A method and apparatus is provided which will attenuate bioelectric interference when measuring the activity in an intact nerve. An electrode probe is provided having first and second electrodes positioned on opposite sides of a thin, flexible, insulating carrier. The probe is inserted between the nerve to be measured and the underlying body tissue with one electrode contacting only the nerve and the second electrode contacting only the tissue. The nerve and the tissue thereby form in effect a Wheatstone bridge about the carrier and the symmetrical electrodes which thus provides a nulling effect on extraneous electrical potentials, while a measurement of nerve potentials appearing as a voltage difference between the electrodes provides a measurement of activity in the nerve. Additional, symmetrical pairs of electrodes may be positioned on the same carrier, and their outputs may electronically be combined for increasing the signal-to-noise ratio in the measurement. The apparatus may also be implanted in a body by covering the first electrode and the portion of the nerve in contact with the electrode with a second insulator which is preferably bonded to the first insulator, the electrode carrier, for electrically isolating both the first electrode and the segment of nerve from surrounding tissues.

Claims

1. An electrode probe for measuring activity in intact nerves comprising,

an electrically non-conductive thin and substantially flat carrier having first and second sides opposite to each other,

a first electrode positioned and attached on the first side of the carrier,

a second electrode positioned and attached on the second side of the carrier and positioned diametrically opposed to the first electrode,

electrically conductive contact areas of the two electrodes being of the same size and located symmetrically in precise opposition to each other,

an insulated wire connected to each of the electrodes, and

differential amplifier means connected to said insulated wires measuring the voltage difference between said electrodes.

2. The apparatus of claim 1 wherein the carrier is a flexible material, and has a length greater than its thickness.

3. The apparatus of claim 1 wherein the size of the contact areas on the two electrodes is substantially equal to the diameter of the nerve to be measured.

4. An electrode probe for measuring activity in intact nerves comprising,

an electrically non-conductive thin and substantially flat carrier having first and second sides opposite to each other,

a first electrode positioned and attached on the first side of the carrier,

a second electrode positioned and attached on the second side of the carrier and positioned diametrically opposed to the first electrode,

electrically conductive contact areas of the first and second electrodes being of the same size and located symmetrically in precise opposition to each other,

an insulated wire connected to each of the first and second electrodes,

a third electrode positioned on the first side of the carrier,

a fourth electrode positioned on the second side of the carrier and positioned diametrically opposed to the third electrode,

electrically conductive contact areas of the third and fourth electrodes being of the same size and located symmetrically in opposition to each other,

an insulated wire connected to each of the third and fourth electrodes,

a first amplifier connected to the insulated wires of the first and second electrodes,

a second amplifier connected to the insulated wires of the third and fourth electrodes,

combining means connected to the outputs of the first and second amplifiers for increasing the signal-to-noise ratio of the output nerve signals.

5. A method of measuring activity in an intact nerve attached to adjacent body tissue while nulling extraneous electrical potentials in the body comprising,

placing an insulating carrier having first and second identical electrodes positioned diametrically on opposite sides of the carrier in the body,

positioning the carrier with the first electrode in contact with the nerve but out of contact with the tissue and the second electrode in contact with the tissue but out of contact with the nerve, and

measuring the voltage between the electrodes whereby activity in the intact nerve is measured but extraneous electrical potentials in the body are nulled.

7. The method of claim 5 including,

attaching the insulator to the insulating carrier.

6. A method of implanting a probe and measuring the activity of an intact nerve attached to adjacent body tissue while nulling extraneous electrical potentials in the body comprising,

placing an insulating carrier having first and second identical electrodes positioned diametrically on opposite sides of the carrier in the body,

positioning the carrier with the first electrode in contact with the nerve but out of contact with the tissue and the second electrode in contact with the tissue but out of contact with the nerve,

covering the first electrode and the portion of the nerve in contact with the first electrode with an insulator for preventing contact with surrounding tissues, and

measuring the voltage between the electrodes.