Advances in the Management of Facial Paralysis Sequelae

Abstract: Background: Despite advances in the management of facial paralysis and its associated sequelae, therapies targeting the lower facial region remain underdeveloped. This thesis aimed to improve both the diagnostic and therapeutic modalities for facial paralysis, with a focus on the lower face.Methods: This thesis employed anatomical and retrospective studies across three key areas. First, high-resolution ultrasound was evaluated for its ability to increase the precision of botulinum toxin injections in the treatment of facial synkinesis and gustatory hyperlacrimation (Paper I), as a preoperative tool to reduce surgical failures in lower lip depressor myectomies (Papers III–IV), and as a method for evaluating the platysma muscle in patients with facial paralysis (Paper V). Second, anatomical exploration was conducted to identify new potential nerve donors for reanimating the lower facial region (Paper II). Third, a novel classification system for facial nerve injuries was applied to a retrospective cohort to stratify patients and to propose a management algorithm for marginal mandibular nerve reconstruction (Paper VI).Results: The use of high-resolution ultrasound significantly increased the accuracy of injections into the facial muscles and lacrimal gland (Paper I). High-resolution ultrasound also provided valuable preoperative information for depressor anguli oris myectomy (Paper IV) and allowed for the assessment of the platysma muscle in both the neck and face (Paper V). A literature review revealed a surgical failure rate of 21% for lower-lip depressor myectomies (Paper III). The ansa cervicalis nerve was established as an anatomically reliable nerve donor for selective marginal mandibular nerve grafting, although awareness of a common anatomical variant and the required modification of the surgical technique are crucial for surgical success (Paper II). A new classification system effectively stratified patients based on the severity of facial nerve injury, allowing for the creation of a management algorithm for marginal mandibular nerve reconstruction (Paper VI).Conclusions: Application of the findings of this thesis may contribute to the improved management of patients with facial paralysis and associated sequelae, particularly with regard to the lower face.