Effect of pulse waveforms on movement amplitudes and perceived discomfort in electric muscle stimulation in unresolved facial nerve palsy

Abstract

Studies on the effects of the pulse waveform used in electrical muscle stimulation on the activations and perceived discomfort of the waveform have been mainly executed on limb muscles with variable results, however, knowledge of these effects on facial muscles is currently lacking. We studied two waveforms, square wave and sinusoidal wavelet, for the activation of the frontalis muscle in 9 individuals with unresolved facial nerve palsy. Both waveforms produced a movement that was greater in amplitude compared with the maximal voluntary movement of the affected side in 8 participants and at least as great as the healthy side's maximal voluntary movement in 4 participants. Both waveforms were equally successful in producing movements, and there was no significant difference in perceived discomfort ratings between the two waveforms. These findings will be useful for the future development of neuroprosthetic applications for reanimating facial muscles using electrical stimulation. Trial registration: ClinicalTrials.gov NCT03496025, registration date March 19, 2018.

Bioelectricity in dental medicine: a narrative review

“…Second, rectangular and sinusoidal pulse shapes are two fundamental waveforms most frequently used in pulsed EStim [ 213 ]. Transcranial magnetic stimulations with rectangular wave cause greater cortical inhibition than those with sinusoidal waves [ 214 ], but there is no difference between effects of two waveforms on facial muscles [ 215 ]. In addition, square waveform promoted M1 polarization but the sinusoidal waveform promoted both M1 and M2 polarization [ 197 ].…”