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Updated: May 10, 2025
Single-stage Dynamic Reanimation of the Smile in Irreversible Facial Paralysis by Free Functional Muscle Transfer
Published on: March 1, 2015
Transcutaneous Facial Nerve Frontal Branch Stimulation to Restore Dynamic Elevation of the Paralyzed Eyebrow in
Roy Xiao1,2,3, Elizabeth R McGonagle1,2, Tessa A Hadlock2,3
1Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, USA.
Background:
While patients commonly recover motion following facial nerve injury, aberrant neural regeneration can lead to synkinesis and chronic nonflaccid facial palsy (NFFP); many patients fail to recover volitional eyebrow elevation.
Objective:
To assess if transcutaneous electrical stimulation of injured frontal branches can achieve eyebrow elevation.
Methods:
We studied healthy volunteers (N = 10) and patients with unilateral NFFP (N = 36). We performed monopolar transcutaneous stimulation of healthy and paralyzed frontal branches with 4-10 mA pulse trains. We measured eyebrow elevation using Emotrics. Differences between stimulated and volitional elevation were assessed using Wilcoxon signed-rank tests.
Results:
Stimulable patients (N = 32) were capable of a median of 7.2 mm (interquartile range [IQR]: 5.9-10.5 mm) healthy eyebrow and 1.5 mm (IQR: 0.5-3.1 mm) paralyzed eyebrow volitional elevation. Transcutaneous stimulation of the healthy hemiface achieved a median of 8.5 mm (IQR: 6.3-10.5 mm) eyebrow elevation and 7.2 mm (IQR: 5.3-8.2 mm) on the paralyzed side. Maximum stimulated eyebrow elevation required a median current of 9 mA (IQR: 8-10 mA), which patients felt would be tolerable for daily use in a facial pacing prosthesis.
Conclusions:
Transcutaneous electrical stimulation can consistently elevate healthy and paralyzed eyebrows in most individuals with NFFP, suggesting they may benefit from dynamic reanimation of eyebrow elevation and possibly other facial regions in future facial pacing systems.
