CMAP amplitude cartography of muscles innervated by the median, ulnar, peroneal, and tibial nerves

Dijk, J. Gert van; Benten, Inesz van; Kramer, C. G. S.; Stegeman, Dick F.

doi:10.1002/(sici)1097-4598(199903)22:3<378::aid-mus11>3.0.co;2-2

Cited by 38 publications

(40 citation statements)

References 15 publications

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“…For example, in electrodiagnostic medicine, the spatial pattern of a surface EMG signal is often reduced to a single value using a large electrode over the skin. 6, 21,22 The implicit assumption is that the signal from such a large electrode approximates the average of the potential distribution beneath the electrode, or more precisely, how it would appear if the electrode were not present. This behavior is sometimes denoted as integration, 12 a term that falsely suggests that the potential increases with increasing electrode size.…”

Section: Introductionmentioning

confidence: 71%

Evidence of Potential Averaging over the Finite Surface of a Bioelectric Surface Electrode

et al. 2009

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Abstract-Most bioelectric signals are not only functions of time but also exhibit a variation in spatial distribution. Surface EMG signals are often ''summarized'' by a large electrode. The effect of such an electrode is interpreted as averaging the potential at the surface of the skin beneath the electrode. We first introduce an electrical equivalent model to delineate this principle of averaging. Next, in a realistic finite element model of EMG generation, two outcome variables are evaluated to assess the validity of the averaging principle. One is the change in voltage distribution in the volume conductor after electrode application. The other is the change in voltage across the high impedance double layer between tissue and electrode. We found that the principle of averaging is valid, once the impedance of the double layer is sufficiently high. The simulations also revealed that skin conductivity plays a role. High-density surface EMG provided experimental evidence consistent with the simulation results. A grid with 120 small electrodes was placed over the thenar muscles of the hand. Electrical nerve stimulation assured a reproducible compound muscle response. The averaged grid response was compared with a single electrode matching the surface of the high-density electrodes. The experimental results showed relatively small errors indicating that averaging of the surface potential by the electrode is a valid principle under most practical conditions.

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Section: Introductionmentioning

confidence: 71%

Evidence of Potential Averaging over the Finite Surface of a Bioelectric Surface Electrode

et al. 2009

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“…One example is the compound muscle action potential (CMAP), which is known to be sensitive to small movements of electrode position of either the active (E1) electrode, placed over the midpoint of muscle, or the reference (E2) electrode placed over the joint or tendon123. Changing the position of the active and reference electrodes will alter the shape and amplitude of the waveform recorded45, and this effect will be different depending on the muscle67. For example, a study showed in the extensor digitorum brevis muscle, the area where the CMAP amplitudes were at least 80% of the maximum CMAP amplitude represented a region of susceptibility (only 1.7 cm 2 ), i.e.…”

mentioning

confidence: 99%

“…For example, a study showed in the extensor digitorum brevis muscle, the area where the CMAP amplitudes were at least 80% of the maximum CMAP amplitude represented a region of susceptibility (only 1.7 cm 2 ), i.e. moving the electrode 7 mm away from the maximum site would cause an amplitude drop of more than 20%6. The flexor digitorum brevis muscle was found, however, less sensitive to changes in electrode positions, with region of susceptibility of 18.4 cm 2 6.…”

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confidence: 99%

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Guidelines to electrode positioning for human and animal electrical impedance myography research

Sanchez

Pacheck

Rutkove

2016

Sci Rep

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The positioning of electrodes in electrical impedance myography (EIM) is critical for accurately assessing disease progression and effectiveness of treatment. In human and animal trials for neuromuscular disorders, inconsistent electrode positioning adds errors to the muscle impedance. Despite its importance, how the reproducibility of resistance and reactance, the two parameters that define EIM, are affected by changes in electrode positioning remains unknown. In this paper, we present a novel approach founded on biophysical principles to study the reproducibility of resistance and reactance to electrode misplacements. The analytical framework presented allows the user to quantify a priori the effect on the muscle resistance and reactance using only one parameter: the uncertainty placing the electrodes. We also provide quantitative data on the precision needed to position the electrodes and the minimum muscle length needed to achieve a pre-specified EIM reproducibility. The results reported here are confirmed with finite element model simulations and measurements on five healthy subjects. Ultimately, our data can serve as normative values to enhance the reliability of EIM as a biomarker and facilitate comparability of future human and animal studies.

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“…The importance of the exact location of the E1 has been illustrated by several prior studies, which noted that subtle changes in position of the recording electrode showed significant differences in the recorded response [11][12][13][14][15]. Mapping the compound muscle action potential from 30 points on a 5 × 6 cm grid on hand and foot muscles, Swenson et al showed areas of prolonged latency, low amplitude, and reduced area, but with waveform morphology consistent with electrode placement over a motor point [16].…”

Section: Discussionmentioning

confidence: 99%

Nerve conduction topography in geriatric hand assessment

Ferdjallah¹,

Wertsch²,

Ahad³

et al. 2005

JRRD

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Abstract-Motor nerve conduction is a noninvasive clinical test used to diagnose nerve problems such as carpal tunnel syndrome or peripheral neuropathy. Current techniques use a single-site recording over a superficial muscle. This traditional approach does not account for the electrical contributions from the other muscles innervated by the nerve being stimulated, which need to be considered with thumb carpometacarpal (CMC) degenerative joint disease (DJD) because these electrical contributions may change the anatomic relationship of the thenar muscles. This study recorded from 15 sites over the thenar eminence during motor nerve conduction studies of the median nerve of 12 young subjects with normal thenar anatomy and 25 elderly subjects with thumb CMC DJD. The maximum compound muscle action potential (CMAP) values did not occur in the same electrode position for the two groups, and traditional single-site recording would have resulted in smaller amplitudes and longer latencies for the elderly than the values noted with the multiple-site recordings. This pilot study of nerve conduction topography mapping with multiple-site recording illustrates that single-site studies may be misleading and supports further exploration of multichannel grid electrodes for topographic display and analysis of the CMAP.

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CMAP amplitude cartography of muscles innervated by the median, ulnar, peroneal, and tibial nerves

Cited by 38 publications

References 15 publications

Evidence of Potential Averaging over the Finite Surface of a Bioelectric Surface Electrode

Evidence of Potential Averaging over the Finite Surface of a Bioelectric Surface Electrode

Guidelines to electrode positioning for human and animal electrical impedance myography research

Nerve conduction topography in geriatric hand assessment

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