Optimal stimulation settings for CMAP scan registrations

Maathuis, Ellen M., Henderson, Robert D., Drenthen, Judith, Hutchinson, Nicole M., Daube, Jasper R., Blok, Joleen H. and Visser, Gerhard H. (2012) Optimal stimulation settings for CMAP scan registrations. Journal of Brachial Plexus and Peripheral Nerve Injury, 7 4.1-4.7. doi:10.1186/1749-7221-7-4

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Author Maathuis, Ellen M.
Henderson, Robert D.
Drenthen, Judith
Hutchinson, Nicole M.
Daube, Jasper R.
Blok, Joleen H.
Visser, Gerhard H.
Title Optimal stimulation settings for CMAP scan registrations
Journal name Journal of Brachial Plexus and Peripheral Nerve Injury   Check publisher's open access policy
ISSN 1749-7221
Publication date 2012-04-30
Sub-type Article (original research)
DOI 10.1186/1749-7221-7-4
Open Access Status DOI
Volume 7
Start page 4.1
End page 4.7
Total pages 7
Place of publication London, United Kingdom
Publisher BioMed Central
Collection year 2013
Language eng
Formatted abstract
Background: The CMAP (Compound Muscle Action Potential) scan is a non-invasive electrodiagnostic tool, which provides a quick and visual assessment of motor unit potentials as electrophysiological components that together constitute the CMAP. The CMAP scan records the electrical activity of the muscle (CMAP) in response to transcutaneous stimulation of the motor nerve with gradual changes in stimulus intensity. Large MUs, including those that result from collateral reinnervation, appear in the CMAP scan as so-called steps, i.e., clearly visible jumps in CMAP amplitude. The CMAP scan also provides information on nerve excitability. This study aims to evaluate the influence of the stimulation protocol used on the CMAP scan and its quantification.

Methods: The stimulus frequency (1, 2 and 3 Hz), duration (0.05, 0.1 and 0.3 ms), or number (300, 500 and 1000 stimuli) in CMAP scans of 23 subjects was systematically varied while the other two parameters were kept constant. Pain was measured by means of a visual analogue scale (VAS). Non-parametric paired tests were used to assess significant differences in excitability and step variables and VAS scores between the different stimulus parameter settings.

Results: We found no effect of stimulus frequency on CMAP scan variables or VAS scores. Stimulus duration affected excitability variables significantly, with higher stimulus intensity values for shorter stimulus durations. Step variables showed a clear trend towards increasing values with decreasing stimulus number.

Conclusions: A protocol delivering 500 stimuli at a frequency of 2 Hz with a 0.1 ms pulse duration optimized CMAP scan quantification with a minimum of subject discomfort, artefact and duration of the recording. CMAP scan variables were influenced by stimulus duration and number; hence, these need to be standardized in future studies.
Keyword CMAP scan
Stimulus duration
Stimulus frequency
Stimulus number
Stimulus-response curve
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: UQ Centre for Clinical Research Publications
Official 2013 Collection
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Citation counts: Scopus Citation Count Cited 4 times in Scopus Article | Citations
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Created: Wed, 13 Feb 2013, 09:32:16 EST by Mrs Maureen Pollard on behalf of Paediatrics & Child Health - RBWH