The waveshape of action potentials recorded with different types of electromyographic needles

Pollak, V.

doi:10.1007/bf02474646

Cited by 28 publications

(9 citation statements)

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“…1). With one recording surface at the fiber and the other at distance 25 pm the amplitude is 30% of the potential recorded unipolarly. When the center-line of the bipolar electrode is parallel to the fiber axis the peak-to-peak amplitude is less than 1 0Oo of the amplitude in unipolar recording.…”

Section: Resultsmentioning

confidence: 99%

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Recording from a Single Motor Unit During Strong Effort

Andreassen

Rosenfalck

1978

IEEE Trans. Biomed. Eng.

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Abstract-During strong voluntary effort it is rarely possible to identify the action potentials from single motor units. In large muscles the most selective recordings are obtained with bipolar wire electrodes. To elucidate this experimental finding we have calculated the extracellular field around a single muscle fiber from an intracellular muscle action potential. This model showed that the selectivity of a bipolar electrode is high provided: i) the diameter of the recording surfaces is less than half the diameter of the muscle fibers;ii) the center distance between the recording surfaces is of the same order or smaller than the diameter of the muscle fibers, and when iii) the center-line between the recording surfaces is oriented perpendicular to the direction of the muscle fibers.A bipolar electrode with these properties will give a maximal attenuation of the field from distant muscle fibers and only two to nine fibers close to the electrode contribute to the recording.Action potentials were recorded from the anterior tibial muscle of normal subjects with a trifilar cut end electrode and a bifilar side hole electrode. The recording surfaces of the side hole electrode can be positioned close to active muscle fibers by gently pulling the electrode at either side of the muscle.The recording surfaces should not be smaller than 25 Jim. Otherwise the impedances of the recording surfaces are so large that the capacitance between wire and muscle tissue degrades the selectivity of the electrode. Improving selectivity by high-pass filtering was avoided. Narrowing the frequency band made action potentials from different motor units appear similar in shape, thereby making identification more difficult. The amplitudes and the power spectra of action potentials recorded with these electrodes were in accordance with the model and no more than one to three motor units were present up to 60% of maximal effort.

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Section: Resultsmentioning

confidence: 99%

“…The extracellular potential for a muscle fiber in situ was therefore calculated [9] v) K(z) _ 1.7 for szu°r-2.8 [9] vi) distance between the centers of the recording surfaces of the bipolar electrodes: 25 ,um.…”

Section: Appendixmentioning

confidence: 99%

Recording from a Single Motor Unit During Strong Effort

Andreassen

Rosenfalck

1978

IEEE Trans. Biomed. Eng.

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“…The influence of the recording electrodes on duration, amplitude, and shape of MUAPs has been the subject of many reports. [5][6][7][8]10,11,13,16 The two most commonly used electrodes are the CNE and the monopolar needle electrode (MNE). This essay discusses the effect of physical variables on the recorded action potentials when comparing CNE to MNE.…”

Section: W Trojaborg MD Phdmentioning

confidence: 99%

“…It would seem, therefore, that the cannula recording must affect the eventual output. Theoretically, 10 if the reference cannula assumes a potential which is equal to the mean value of the tissue potential along the surface of the cannula, electrically active areas will eventually average out and the cannula will end up being electrically indifferent. The cannula, however, does not likely ever actually reach a zero potential, so there is always some loss of the active recording by cancellation from the reference.…”

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confidence: 99%

The concentric versus the monopolar needle electrode: The case for monopolar needles

Joynt¹

1998

Muscle Nerve

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“…5 The shape of MUAPs recorded with MNE and CNE is very similar. 5,13,19 In the past, MNE 8 were preferred because they were cheaper than CNE 8 and supposedly caused less discomfort. 16 Today, an inexpensive, disposable, smaller diameter, and sharper CNE is available, and may now be the electrode of choice.…”

mentioning

confidence: 98%

The concentric versus the monopolar needle electrode: The case for concentric needles

Trojaborg

1998

Muscle Nerve

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The waveshape of action potentials recorded with different types of electromyographic needles

Cited by 28 publications

References 1 publication

Recording from a Single Motor Unit During Strong Effort

Recording from a Single Motor Unit During Strong Effort

The concentric versus the monopolar needle electrode: The case for monopolar needles

The concentric versus the monopolar needle electrode: The case for concentric needles

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