NCS-EMG (ABNORMAL RESTING MOTOR UNIT ACTIVITY)

SUMMARY

ABNORMAL RESTING MOTOR UNIT ACTIVITY
Pathologic waveforms can be generated from resting muscle fiber/motor unit due to many reasons.

1. Fasciculations: spontaneous discharges originating from any part of a single motor unit and result in intermittent muscle fiber contraction. Pathological if associated with FIB or PSW.
- Causes: anterior horn cell disease, CJD, thyrotoxicosis, tetany.

2. Myokymia: groups of MUAPs firing repetitively.
- Facial myokymia causes: MS, pontine gliomas.
- Limb myokymia causes: radiation plexopathy, compression neuropathy.

Reference(s)

Wilkinson, I., Furmedge, D. and Sinharay, R. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press. Get it on Amazon.
Feather, A., Randall, D. and Waterhouse, M. (2020). Kumar And Clark’s Clinical Medicine. 10th ed. S.L.: Elsevier Health Sciences. Get it on Amazon.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].