Author(s)
Seth J. Davis, MD
Kyle S. Kimura, MD
Alex S. Ortiz, MD
Shiayin F. Yang, MD
Priyesh N. Patel, MD
Sanjeev D. Nandedkar, PhD
Scott J. Stephan, MD
Affiliation(s)
Department of Otolaryngology – Head & Neck Surgery, Vanderbilt University Medical Center, Nashville, TN
Division of Facial Plastic and Reconstructive Surgery, Vanderbilt University Medical Center, Nashville, TN
Abstract:
Background: Quantitative EMG (qEMG) analysis measures various components of the EMG waveform for objective analysis. Two methods, turns/amplitudes (TAA) and multi-motor unit potential (multi-MUP), have been validated in other anatomic locations. This study aims to characterize synkinetic versus nonpathologic facial mimetic muscles using qEMG.
Learning
Objectives: Understand the mechanism and advantages of qEMG. Identify potential roles for qEMG in management of facial synkinesis.
Study
Objective: Demonstrate efficacy of qEMG in synkinetic muscles of facial expression.
Design Type: Prospective case-control study
Methods: Needle EMG was performed in 3 muscles (frontalis, zygomaticus major, platysma) across 10 controls and 15 patients with facial synkinesis. Both multi-MUP analysis and TAA at variable force contractions were performed over 5 epochs. Pooled data are used to compare pathologic versus nonpathologic and control muscles.
Results: Multi-MUP demonstrated increased average amplitude and firing rate, and decreased turns in pathologic versus nonpathologic and control muscles (P<0.05). A greater number of pathologic muscles demonstrated polyphasic waveforms (P<0.01).
Pooled TAA showed decreased turns/s at maximal contraction, and increased turns/s with synkinetic movements in all pathologic versus nonpathologic and control muscles. Mean amplitude (MA) was decreased in both pathologic and nonpathologic muscles compared to controls, but was greater in pathologic muscles with synkinetic actions (P<0.05).
Conclusions: This represents the first report of quantitative EMG analysis in facial synkinesis. Facial qEMG identifies objective differences in EMG signals of synkinetic versus nonpathologic muscles. These features could help guide future strategies for rehabilitation, chemodenervation and surgical management in patients with facial nerve injuries.