Needle impedance electromyography and electrical impedance imaging for enhanced muscle diagnostics
Described herein are embodiments of methods and apparatus for diagnosing neuromuscular diseases using an impedance-EMG needle, and for generating electrical impedance images using an impedance needle. Some embodiments provide an apparatus including an impedance-EMG needle, including both EMG electrodes and impedance electrodes, to measure both active and passive electrical properties of muscle. Other embodiments provide an apparatus including an impedance needle, including a plurality of impedance electrodes to measure impedance in tissue surrounding the impedance needle to generate an electrical impedance image. Use of such methods and apparatus may be advantageous in improving the accuracy of assessing and diagnosing neuromuscular disease.
1. An impedance-EMG needle configured to be inserted into tissue, the impedance-EMG needle comprising:
an insulative shaft of the impedance-EMG needle;
an active EMG electrode, disposed at a distal end of the insulative shaft, configured to measure active electrical properties of the tissue;
a reference EMG electrode disposed on an outer layer of the insulative shaft and extending to the distal end of the insulative shaft;
a plurality of impedance ring electrodes, wherein the plurality of impedance ring electrodes comprises a plurality of current impedance electrodes and a plurality of voltage impedance electrodes and wherein the plurality of voltage impedance electrodes is disposed between the plurality of current impedance electrodes; and
wherein the plurality of impedance ring electrodes is configured to measure passive electrical properties of the tissue in response to an electrical current with a frequency comprising 10 kHz to 10 MHz.
2. The impedance-EMG needle of claim 1 , wherein the plurality of impedance ring electrodes is configured as point electrodes on the insulative shaft of the impedance-EMG needle.
3. The impedance-EMG needle of claim 1 , wherein the electrical current has a frequency comprising 10 kHz to 100 kHz.
4. The impedance-EMG needle of claim 1 , wherein the plurality of impedance ring electrodes comprises four ring electrodes disposed along the insulative shaft of the impedance-EMG needle, and wherein:
an outer two ring electrodes are current impedance electrodes; and an
inner two ring electrodes are voltage impedance electrodes.
5. The impedance-EMG needle of claim 1 , wherein the tissue is muscle, and wherein:
the active EMG electrode is configured to measure active electrical properties of the muscle when the muscle is at rest and when the muscle is contracted; and
the plurality of impedance ring electrodes is configured to measure passive electrical properties of the muscle when the muscle is at rest and when the muscle is contracted.
6. The impedance-EMG needle of claim 1 , wherein the impedance-EMG needle is further configured to measure a temperature of tissue.
7. The impedance-EMG needle of claim 1 , wherein the plurality of impedance ring electrodes is configured to measure passive electrical properties of the tissue with the needle being inserted into tissue.
8. A system for assessing neuromuscular disease of tissue, the system comprising:
an impedance-EMG needle configured to be inserted into tissue, the impedance-EMG needle comprising:
an insulative shaft of the impedance-EMG needle;
an active EMG electrode, disposed at a distal end of the insulative shaft, configured to measure active electrical properties of the tissue;
a plurality of impedance ring electrodes, wherein the plurality of impedance ring electrodes comprises a plurality of current impedance ring electrodes and a plurality of voltage impedance electrodes and wherein the plurality of voltage impedance electrodes is disposed between the plurality of current impedance electrodes; and
wherein the plurality of impedance ring electrodes is configured to measure passive electrical properties of the tissue in response to an electrical current with a frequency comprising 10 kHz to 10 MHz; and
at least one computing device configured to receive and analyze at least one signal from the impedance-EMG needle.
9. The system of claim 8 , wherein the electrical current has a frequency comprising 10 kHz to 100 kHz.
10. The system of claim 8 , wherein the impedance-EMG needle includes a concentric EMG design, wherein the active EMG electrode comprises:
a first EMG electrode comprising a reference EMG electrode disposed as an outer layer of the insulative shaft; and a second EMG electrode comprising an active EMG electrode disposed inside the insulative shaft.
11. The system of claim 8 , wherein the at least one computing device is configured to: receive and analyze at least one first signal, comprising first information relating to the active electrical properties of the tissue, from the at least one EMG electrode; and
receive and analyze at least one second signal, comprising second information relating to the passive electrical properties of the tissue, from the plurality of impedance ring electrodes.
12. The system of claim 11 , further comprising at least one display, and wherein the at least one computing device is configured to display the first information and the second information on the at least one display.
13. The system of claim 8 , wherein the tissue is muscle, and wherein:
the active EMG electrode is configured to measure active electrical properties of the muscle when the muscle is at rest and when the muscle is contracted; and
the plurality of impedance ring electrodes is configured to measure passive electrical properties of the muscle when the muscle is at rest and when the muscle is contracted.
14. The system of claim 8 , wherein the impedance-EMG needle is further configured to measure a temperature of tissue.
15. The system of claim 8 , wherein the plurality of impedance ring electrodes is configured to measure passive electrical properties of the tissue with the needle being inserted into tissue.
16. A method for assessing neuromuscular disease of tissue, the method comprising:
inserting an impedance-EMG needle into the tissue, the impedance-EMG needle comprising:
an insulative shaft of the impedance-EMG needle;
an active EMG electrode, disposed at a distal end of the insulative shaft, configured to measure active electrical properties of the tissue;
a reference EMG electrode disposed on an outer layer of the insulative shaft and extending to the distal end of the insulative shaft;
a plurality of impedance ring electrodes, wherein the plurality of impedance ring electrodes comprises a plurality of current impedance electrodes and a plurality of voltage impedance electrodes and wherein the plurality of voltage impedance electrodes is disposed between the plurality of current impedance electrodes;
wherein the plurality of impedance ring electrodes is configured to measure passive electrical properties of the tissue in response to an electrical current with a frequency comprising 10 kHz to 10 MHz; and
determining, from the active electrical properties and the passive electrical properties, a state of the tissue.
17. The method of claim 16 , wherein the electrical current has a frequency comprising 10 kHz to 100 kHz.
18. The method of claim 16 , wherein the tissue is muscle, and wherein:
the active EMG electrode is configured to measure active electrical properties of the muscle when the muscle is at rest and when the muscle is contracted; and
the plurality of impedance ring electrodes is configured to measure passive electrical properties of the muscle when the muscle is at rest and when the muscle is contracted.
19. The method of claim 16 , wherein the impedance-EMG needle is further configured to measure a temperature of tissue.