April 2020 HSC Section 4 - Plastic and Reconstructive Problems

Management of Flaccid Facial Paralysis

may be candidates for reinnervation of the native facial musculature. Nevertheless, in the authors’ experience, the best outcomes are observed when interventions take place within a year after paralysis onset. Patients who have paralysis longer than 2 years will often require functional muscle or tendon transfer to mitigate nonfunctional native facial musculature (see Fig. 1 , decision point 1). For patients who have exces- sive comorbidities, or those who do not wish to undergo more invasive procedures, static facial suspension techniques may be considered. Proximal Facial Nerve Status The second factor used to determine the optimal treatment strategy is the functional status and accessibility of the proximal ipsilateral facial nerve (see Fig. 1 , decision point 2). There are numerous scenarios that preclude accessibility or utilization of the proximal stump of the facial nerve, the most common of which is very proximal facial nerve sacrifice or transection at the cerebellopontine angle, making nerve graft- ing impossible. In other situations, the proximal facial nerve trunk is anatomically intact but presumed nonfunctional. This may occur when a patient develops dense facial pa- ralysis following temporal bone trauma, middle cranial fossa surgery, or temporal bone surgery. Denervation may be assumed if patients have not shown any discernible functional facial nerve recovery by 12 months after the insult and electromyogram demonstrates a lack of electrophysiologic reinnervation potentials. In these cases, other cranial nerves will be required to drive motor function of the face. Facial Musculature and Distal Facial Nerve Status A third determinant in selecting a facial reanimation treatment strategy is the status of the distal facial nerve branches and facial musculature (see Fig. 1 , decision points 3 and 4). It is desirable to use native facial mimetic muscles when possible because no current procedure can recreate the complex motion and vector of these muscles. Fortunately, many patients presenting with facial paralysis for less than 2 years have accessible distal facial nerve branches and facial musculature. The notable exception is in patients who have undergone radical resections of head and neck or parotid neo- plasms without preservation of distal facial nerve branches. Nevertheless, it should be noted that, in the authors’ experience, even in situations in which a radical parotidec- tomy has been performed, distal facial nerve branches are commonly still present and can be used. The more difficult scenario occurs when extirpation of head and neck neoplasms involves resection of facial mimetic muscles, which necessitates functional muscle transfer. The best dynamic outcomes (better static tone, dynamic movement, and less synki- nesis) are observed when it is possible to directly repair discontinuity of the facial nerve. Nonetheless, it is very important to obtain a tension-free neurorrhaphy to ensure the best outcomes possible. 5,6 In cases in which defects are 5 to 10 mm, addi- tional proximal facial nerve length may be obtained through mobilization within the mastoid cavity. 7,8 However, mobilization of the facial nerve may theoretically result in transient perfusion changes to the nerve, which is a risk that must be weighed in the decision-making process. In cases in which a tension-free repair cannot be accomplished but distal and proximal portions of the facial nerve are present and functional, an interposition nerve graft should be used. Common donor nerves include SURGICAL APPROACHES TO TREATMENT OF FLACCID FACIAL PARALYSIS Dynamic Reanimation Procedures Primary nerve repair and interposition grafting

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