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 comprising:
a shaft configured to be inserted subcutaneously into tissue;
a plurality of current impedance electrodes, each current impedance electrode of the plurality of current impedance electrodes being disposed around the shaft; and
a plurality of voltage impedance electrodes, each voltage impedance electrode of the plurality of voltage impedance electrodes being disposed around the shaft between the plurality of current impedance electrodes; and
an active EMG electrode, disposed at a distal end of the shaft of the impedance-EMG needle, wherein the active EMG electrode is configured to enable simultaneous operation of the active EMG electrode with the plurality of current impedance electrodes and the plurality of voltage impedance electrodes.
2 . The impedance-EMG needle of claim 1 , further comprising a reference electrode disposed on an outer surface of the shaft.
3 . The impedance-EMG needle of claim 1 , wherein the current impedance electrodes, of the plurality of current impedance electrodes, are two current ring electrodes.
4 . The impedance-EMG needle of claim 1 , wherein the voltage impedance electrodes, of the plurality of voltage impedance electrodes, are two voltage ring electrodes.
5 . The impedance-EMG needle of claim 1 , wherein the plurality of current impedance electrodes and the plurality of voltage impedance electrodes are each separated by approximately 1.0 mm.
6 . The impedance-EMG needle of claim 5 , wherein the plurality of current impedance electrodes and the plurality of voltage impedance electrodes each have a width of 1.0 mm.
7 . The impedance-EMG needle of claim 1 , wherein the shaft has a length ranging from 25 mm to 40 mm.
8 . The impedance-EMG needle of claim 1 , wherein the active EMG electrode is configured to be simultaneously operated with the plurality of current impedance electrodes and the plurality of voltage impedance electrodes.
9 . A method of diagnosing a neuromuscular disease in a subject, the method comprising:
inserting an impedance-EMG needle into a tissue of the subject, the impedance-EMG needle comprising:
a shaft configured to be inserted subcutaneously into tissue;
a plurality of current impedance electrodes, each current impedance electrode of the plurality of current impedance electrodes being disposed around the shaft;
a plurality of voltage impedance electrodes, each voltage impedance electrode of the plurality of voltage impedance electrodes being disposed around the shaft between the plurality of current impedance electrodes; and
an active EMG electrode, disposed at a distal end of the shaft of the impedance-EMG needle, wherein the active EMG electrode is configured to enable simultaneous operation of the active EMG electrode with the plurality of current impedance electrodes and the plurality of voltage impedance electrodes;
passing an electrical current having a frequency between 1 kHz to 10 MHz between the plurality of current impedance electrodes and the plurality of voltage impedance electrodes;
measuring at least one signal from the impedance-EMG needle; and
determining whether the subject has a neuromuscular disease.
10 . The method of claim 9 , wherein measuring the at least one signal from the impedance-EMG needle comprises measuring an EMG signal, an impedance signal, or a combination thereof.
11 . The method of claim 10 , wherein the impedance signal comprises a voltage impedance signal, a current impedance signal, or a combination thereof.
12 . The method of claim 10 , wherein measuring the at least one signal from the impedance-EMG needle comprises measuring an EMG signal and an impedance signal simultaneously.
13 . The method of claim 9 , wherein the current impedance electrodes, of the plurality of current impedance electrodes, are two current ring electrodes.
14 . The method of claim 9 , wherein the voltage impedance electrodes, of the plurality of voltage impedance electrodes, are two voltage ring electrodes.
15 . The method of claim 9 , wherein the impedance-EMG needle further comprises a reference electrode disposed on an outer surface of the shaft.
16 . A method of performing electrical impedance myography (EIM) in a subject comprising:
inserting an impedance-EMG needle into a tissue of the subject, the impedance-EMG needle comprising:
a shaft configured to be inserted subcutaneously into tissue;
a plurality of current impedance electrodes, each current impedance electrode of the plurality of current impedance electrodes being disposed around the shaft;
a plurality of voltage impedance electrodes, each voltage impedance electrode of the plurality of voltage impedance electrodes being disposed around the shaft between the plurality of current impedance electrodes; and
an active EMG electrode, disposed at a distal end of the shaft of the impedance-EMG needle, wherein the active EMG electrode is configured to enable simultaneous operation of the active EMG electrode with the plurality of current impedance electrodes and the plurality of voltage impedance electrodes;
passing an electrical current having a frequency between 1 kHz to 10 MHz between the plurality of current impedance electrodes and the plurality of voltage impedance electrodes; and
measuring at least one signal from the impedance-EMG needle.
17 . The method of claim 16 , wherein measuring the at least one signal from the impedance-EMG needle comprises measuring an EMG signal, an impedance signal, or a combination thereof.
18 . The method of claim 17 , wherein the impedance signal comprises a voltage impedance signal, a current impedance signal, or a combination thereof.
19 . The method of claim 16 , wherein the current impedance electrodes, of the plurality of current impedance electrodes, are two current ring electrodes.
20 . The method of claim 16 , wherein the voltage impedance electrodes, of the plurality of voltage impedance electrodes, are two voltage ring electrodes.