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Kobylarz et al. Plast Aesthet Res 2023;10:2 https://dx.doi.org/10.20517/2347-9264.2022.38 Page 11 of 20

Figure 8. Triggered EMG recordings demonstrating large amplitude, polyphasic compound muscle action potentials (CMAPs) in the
orbicularis oculi muscle during facial nerve branch stimulation, sweeping across the surgical field. The largest amplitude response
corresponds to the location closest to the facial nerve branch. Amplitude is 20 µV per division.

demyelination) reduces the recruitment of motor unit action potentials. After approximately 14 days, active
denervation of muscle, as evidenced by increased abnormal spontaneous activity, fibrillation potentials, and
positive sharp waves, appears in a proximal to a distal pattern, initially occurring in paraspinal muscles.

It should be noted, however, that denervation potentials require up to 6 weeks to appear in distal muscles;
therefore, the sensitivity of electrodiagnosis can be reduced in acute or even subacute radiculopathy. Over
the next 3-18 months, unstable, long duration and polyphasic motor units are seen, reflecting early