Pathogenesis, diagnosis and therapy of facial synkinesis: A systematic review and clinical practice recommendations by the international head and neck scientific group

Abstract

IntroductionPost-paralytic facial synkinesis after facial nerve injury produces functional disabilities and mimetic deficits, but also cosmetic and non-motor psychosocial impairments for the patients. These patients typically have a high and continuous high motivation for rehabilitation. The aim is to inform the affected patients and their therapeutic professionals (otorhinolaryngologist - head and neck surgeons; oral-maxillofacial surgeons, plastic and reconstructive surgeons, neurosurgeons, neurologists, and mime therapists be it speech and language therapy- or physiotherapy-based) and to provide practical recommendations for diagnostics and a stepwise systematic treatment approach of facial synkinesis.MethodsIn the first phase, a systematic literature search on the topic in PubMed and ScienceDirect starting in 2008 resulted in 132 articles. These were the basis for the review and a comprehensive series of consensus statements on the most important diagnostic tests and treatment options. In the second phase, one consensus article circulated among the membership of the International Head and Neck Scientific Group until a final agreement was reached for all recommendations.ResultsDiagnostics should include a standardized assessment of the degree of synkinesis using validated clinician-graded instruments and synkinesis-specific patient-reported outcome measures. Treatments for facial synkinesis include facial training mainly based on facial biofeedback retraining, chemodenervation with botulinum toxin, selective neurectomy, myectomy, and any combination treatment of these options.ConclusionA basic understanding of the pathomechanisms of synkinesis is essential to understand the treatment strategies. A standardized assessment of the synkinetic symptoms and the individual synkinesis pattern is needed. The first-line treatment is facial training, followed by botulinum toxin. Surgery is reserved for individual cases with unsatisfactory first-line treatment.

Ocular and Palpebral Manifestations of Facial Palsy: An Epidemiologic Descriptive Study

“…Some studies have estimated that aberrant regeneration can present in up to 9% of cases, while 30% of cases suffered from this outcome in our study, which reflects more recent evidence. [20][21][22] It is important to note that 56.7% of the patients in our study underwent medical treatment with 2 or more options.…”

Selective neurectomy for nonflaccid facial palsy

“…The impact of facial synkinesis is significant, resulting in functional and aesthetic deficits as well as psychosocial distress, ultimately leading to a decreased quality of life [5][6][7]. The pathophysiology underlying facial synkinesis is multifactorial, including aberrant regeneration and reinnervation of facial muscles as above, random collateral sprouting of damaged axons, ephaptic coupling due to incomplete myelination of axons resulting in excitation of adjacent axons, hyperexcitability at the facial nucleus, and cortical reorganization following facial nerve regeneration [8].…”

“…Facial synkinesis, or nonflaccid facial paralysis (NFFP), is the recovery endpoint in approximately 15–55% of facial paralysis of all etiologies [1–3,4 ▪▪ ]. This phenomenon is thought to be the product of aberrant regeneration of the facial nerve following an axonal insult, resulting in off-target involuntary muscle activation that occurs simultaneously with a voluntary facial movement.…”

Minimization of facial synkinesis

“…Synkinesis represents a delayed complication of facial nerve paralysis characterized by involuntary activation of specific facial muscles concurrent with voluntary facial movements [6,7]. The incidence of postparalytic facial synkinesis, with reports ranging from 10 to 55%, has not been specifically investigated and likely is influenced by the underlying etiology of facial nerve paralysis [7,8]. Synkinesis typically arises at least four months and may be delayed until up to 40 months following the initial onset of paralysis [6].…”

“…Synkinesis typically arises at least four months and may be delayed until up to 40 months following the initial onset of paralysis [6]. Although there are numerous proposed mechanisms for the pathogenesis of facial nerve synkinesis, it is generally accepted that synkinesis is the result of disorganized and nonspecific axonal regeneration following an axondisrupting injury (axonotmesis) [7,9]. When axons at the proximal end of the injured facial nerve regrow, collateral sprouting can lead to a single axon ultimately innervating multiple peripheral facial nerve branches.…”