Depressor Reanimation after Facial Nerve Paralysis

Facial expressions play a fundamental role in interpersonal communication and interaction; consequently, facial palsy has profound effects on the quality of life of patients. Reanimation of lower lip depressors is rarely addressed during facial reanimation but is as important as treating the eye sphincter and the lip levators. Depressors of lower lip are vital for full denture smile and the expression of facial emotions. Static and dynamic techniques are used to reanimate the lower lip depressors. Static techniques provide stationary results either by weakening the contralateral normal side to achieve symmetry using botulinum toxin injection, depressor labi inferioris myectomy and marginal mandibular nerve neurectomy, or by creating static slings and tightening procedures on the affected side. Dynamic techniques provide functional results by reanimating the affected depressor complex using nerve transfers, muscle transfers, and direct muscle neurotization. The purpose of this article is to present an overview of the literature on the applications of these techniques in lower lip reanimation. Furthermore, preoperative evaluation and indications are also discussed.