How are muscle fiber recruitment patterns determined in electrodiagnosis?

Updated: Mar 01, 2019
  • Author: Adam B Agranoff, MD; Chief Editor: Stephen Kishner, MD, MHA  more...
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Answer

Answer

With minimal volitional activity, the recruitment patterns of muscle are normal. An individual muscle fiber begins to fire, reaching a threshold of 15-20 Hz, at which point the original fiber recruits a second fiber, which fires up to 15-20 Hz, and so on until there is full recruitment of the muscle.

Determination of recruitment patterns is difficult and requires more modern, computerized equipment; however, recruitment patterns provide critical information for determining the degree of injury and prognosis. Furthermore, this information is helpful in identifying individuals who are malingering. A patient may not be fully cooperative in manual muscle testing for weakness. Determination of the recruitment pattern, however, is not dependent on patient cooperation.


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