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The impact of facial paralysis on a patient can be pervasive, affecting the quality of life due to psychosocial and functional effects. While the inability to close the eye, breathe easily through the nose, or maintain oral competence can be very problematic, losing the ability to smile meaningfully or appear symmetric at rest can be even more significant for many. When the facial nerve is transected, immediate surgical repair with primary neurorrhaphy is generally the preferred treatment option. However, this is not always feasible and delayed repair via interposition grafting or nerve transfer may be required. Regardless of the technique employed, the return of function after a facial nerve transection injury is a slow process affecting many aspects of facial function and aesthetics. For this reason, an interprofessional team consisting of not only a peripheral nerve surgeon such as a plastic or facial plastic surgeon or otolaryngologist but also an ophthalmologist and physical and speech therapists is the most effective means of providing holistic care for patients with facial paralysis. This activity reviews the evaluation and management of facial nerve injuries and highlights the role of the interprofessional team in the care of patients with facial paralysis who undergo facial nerve repair. Objectives: Delineate the indications for and contraindications to facial nerve repair. Appraise the techniques available to reinnervate the mimetic muscles after facial nerve injury. Employ effective evaluation methods to determine whether or not facial nerve repair should be performed. Effectively implement interprofessional team strategies for improving care coordination and outcomes in patients with facial paralysis requiring facial nerve repair. Access free multiple choice questions on this topic.

Due to the myriad roles the face plays, the impact of facial paralysis can be pervasive, negatively affecting quality of life due to psychosocial and functional effects. While the inability to close the eye, breathe easily through the nose, or maintain oral competence can be very problematic, losing the ability to smile or even to appear symmetric at rest can be even more significant for many patients, especially young women, and may lead to depression in addition to decreased quality of life.[1][2] The differential diagnosis for facial paralysis is extensive, including Bell's palsy, Ramsay Hunt syndrome, Lyme disease, cerebellopontine angle (CPA) tumors, temporal bone fractures, parotid malignancies, autoimmune disorders, iatrogenic and traumatic injuries, and many others (see image).[3][4] This article will focus on the evaluation and management of traumatic facial paralysis, specifically cases that involve transection of the facial nerve. When the facial nerve is transected, immediate surgical repair with primary neurorrhaphy is generally the preferred treatment option.[5][6] If coaptation without tension is impossible, a cable graft interposition using the greater auricular or sural nerves may be necessary. The success rate of nerve repair, defined as a return to House-Brackmann grade III function or better, varies from 5% to 86% within the literature.[4][7] However, repairing the nerve at the time of the injury is not always feasible; either the injury is not recognized immediately, or the nerve is transected in a location that precludes suture coaptation of the nerve stumps, such as in the CPA. When the proximal facial nerve is unavailable to reconnect to the distal stump, a nerve transfer may be the best method of restoring facial function.[7]

When the facial nerve is transected, immediate surgical repair with primary neurorrhaphy is generally the preferred treatment option.[5][6] If coaptation without tension is impossible, a cable graft interposition using the greater auricular or sural nerves may be necessary. The success rate of nerve repair, defined as a return to House-Brackmann grade III function or better, varies from 5% to 86% within the literature.[4][7] However, repairing the nerve at the time of the injury is not always feasible; either the injury is not recognized immediately, or the nerve is transected in a location that precludes suture coaptation of the nerve stumps, such as in the CPA. When the proximal facial nerve is unavailable to reconnect to the distal stump, a nerve transfer may be the best method of restoring facial function.[7] Any technique employed other than direct coaptation of the severed facial nerve stumps at the time of injury will have associated risks. Delayed primary repair often requires a facial nerve exploration, which risks injury to other facial structures, including the parotid gland and duct, as well as other potentially intact facial nerve branches. Interposition grafting and nerve transfer introduce the potential for donor site morbidity, a critical factor when planning for and counseling patients before surgery. Regardless of the technique employed, the return of function after a facial nerve transection injury is a slow process affecting many aspects of facial function and aesthetics. For this reason, an interprofessional team consisting of not only a peripheral nerve surgeon such as a plastic or facial plastic surgeon or otolaryngologist but also an ophthalmologist and physical and speech therapists is the most effective means of providing holistic care for patients with facial paralysis.

The biggest risk of nerve repair or transfer is no return of function is achieved. Risk factors for procedural failure include prolonged paralysis of greater than 6 to 12 months before the intervention, advanced age or poor health status, and performing multiple neurorrhaphies, as are required for interposition grafting. Each neurorrhaphy introduces additional opportunities for axonal loss. Postoperative radiotherapy does not appear to affect functional outcomes, although chemotherapy is known to cause facial paralysis.[60][61] When the facial nerve is repaired proximal to the pes anserinus or a nerve transfer to the main trunk is performed, the expected outcome is synkinetic movement. Synkinetic movement is not a complication per se but represents a suboptimal outcome. Synkinesis may impair voluntary movements, particularly smiling, resulting in marked facial asymmetry and lower quality of life despite restoration of tone and movement. While numerous theories regarding the etiology of synkinesis have been proposed, it is currently thought that a major contributing factor to synkinesis is the misdirection of axons to different neuromuscular junctions from the ones they innervated before the injury.[62][63] Additionally, axons that terminate in multiple rather than single neuromuscular junctions will cause discoordinated movement and increase the basal firing rate of the innervated muscle and its resting tone. Botulinum toxin injections and facial physical therapy are the mainstay treatment options for this problem, but selective neurectomy and myomectomy have also been successfully employed.[64][65][66][67][68] When possible, synkinesis may be avoided or reduced by preferentially reinnervating facial nerve branches rather than the main trunk itself. While the site of the injury determines at which point a nerve repair will take place, the surgeon has discretion over where to perform a nerve transfer. For this reason, masseteric nerve to buccal branch transfers are favored over masseteric nerve to main trunk facial nerve transfers; these procedures may also be combined with selective neurectomy or myomectomy to further reduce synkinesis.[54]

Additionally, axons that terminate in multiple rather than single neuromuscular junctions will cause discoordinated movement and increase the basal firing rate of the innervated muscle and its resting tone. Botulinum toxin injections and facial physical therapy are the mainstay treatment options for this problem, but selective neurectomy and myomectomy have also been successfully employed.[64][65][66][67][68] When possible, synkinesis may be avoided or reduced by preferentially reinnervating facial nerve branches rather than the main trunk itself. While the site of the injury determines at which point a nerve repair will take place, the surgeon has discretion over where to perform a nerve transfer. For this reason, masseteric nerve to buccal branch transfers are favored over masseteric nerve to main trunk facial nerve transfers; these procedures may also be combined with selective neurectomy or myomectomy to further reduce synkinesis.[54] One risk of performing nerve transfers, particularly in the case of the masseteric nerve to buccal branch transfer undertaken more than 72 hours after injury, is the possibility of reinnervating the wrong nerve branch. Without the ability to stimulate the recipient nerve, it is possible to select a suboptimal branch that may not produce the desired precise effect. While suboptimal branch selection is unlikely to result in movements completely different from those intended as long as the recipient branch is in roughly the correct location, it may be that the resulting smile vector, for example, is not entirely symmetric with the uninjured side. Most facial reanimation surgeons prefer to reinnervate native facial muscles whenever possible, but in cases of suboptimal outcomes of nerve transfer, intractable synkinesis, or longstanding paralysis of greater than 12-18 months, free muscle transfer may be employed instead of nerve repair or transfer.[69] When an uninjured nerve is sacrificed in grafting or transfer, there is always a risk of donor site morbidity. Greater auricular and sural nerve harvest site hypesthesia is common, predictable, and usually results in nothing more than auricular lobule numbness and lateral ankle and foot numbness, respectively. While uncommon, the potential for developing painful neuromas at these sites does exist. These neuromas can be treated with excision and burying the cut nerve end into muscle.

When an uninjured nerve is sacrificed in grafting or transfer, there is always a risk of donor site morbidity. Greater auricular and sural nerve harvest site hypesthesia is common, predictable, and usually results in nothing more than auricular lobule numbness and lateral ankle and foot numbness, respectively. While uncommon, the potential for developing painful neuromas at these sites does exist. These neuromas can be treated with excision and burying the cut nerve end into muscle. Motor nerve sacrifice, on the other hand, may carry a greater risk of morbidity. Masseteric nerve sacrifice is generally well tolerated, with little more than the loss of some facial volume due to muscle atrophy; most patients do not complain of decreased bite force. Cross-face nerve grafting also tends to be well tolerated, despite requiring sural nerve harvest, and there tends to be minimal morbidity other than a scar from the contralateral dissection required to access the uninjured facial nerve. While sacrificing an uninjured facial nerve branch to supply axons to the cross-face graft may risk weakening the normal side smile, this is rarely seen in practice. The highest risk for donor site morbidity among these procedures occurs with the hypoglossal-facial nerve transfer because of the potential for dysphagia and dysarthria accompanying tongue weakness. When the entire hypoglossal nerve is transferred, facial outcomes are good because of the high axon count in the hypoglossal nerve, but the morbidity is severe.[50] The sacrifice of only part of the hypoglossal nerve via end-to-side coaptation or interfascicular dissection and transfer decreases morbidity dramatically but also compromises results by reducing the number of axons redirected into the facial nerve.[33]

Providing care to patients undergoing facial reinnervation procedures involves a comprehensive clinical team that typically includes a plastic surgeon, facial plastic surgeon, neurotologist or otolaryngologist, and a physical therapist to provide postoperative rehabilitation. In addition, a clinical photographer may be helpful for regular photodocumentation of progress, and if botulinum toxin injections are required to manage synkinesis, a nurse or advanced practice provider may provide them. In many cases, the etiology of the paralysis also necessitates the involvement of other specialists, such as a surgical oncologist, radiation oncologist, medical oncologist, radiologist, audiologist, ophthalmologist, and wound care nurse. Nursing care is particularly vital for these patients who need perioperative care, support, and education. The outcomes of facial reinnervation depend on the timing of surgery and the rehabilitation process.[70] It may take more than a year for a patient to experience the full benefit of the procedure. To maximize the results of a nerve transfer, facial muscle retraining with physical therapy is essential, and patients must be aware of this before the surgery. Additional procedures, particularly periorbital interventions such as upper eyelid weight implantation, tarsorrhaphy, and tarsal strip-lateral canthopexy, are often performed concurrently with nerve repair or subsequently to it to enhance patient satisfaction.[4] [level 5]