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Clinical Review & Education Special Communication

A Contemporary Approach to Facial Reanimation

to the pubic tubercle. The flap is harvested by removing approxi mately one-thirdof thewidthof themuscle along a lengthof roughly 15 cm. Before inset, the muscle is further trimmed along its superfi cial surface to reduce excessive bulk that would otherwise result in a facial contour irregularity. For inset, a flap is elevatedmedially to the modiolus by means of a preauricular incision extended slightly be lowthemandible. Thegracilismuscle is secured to themodiolususing 5 polyglactin 910 sutures, stretched to its resting length, and su tured to the true temporalis fascia, taking into account the patient’s smile vector. Microvascular anastomoses ensue. In the 2-stage pro cedure, the branch of the obturator nerve to the gracilis is then co apted to the banked CFNG stump deep to the gingivobuccal sulcus. In the single-stage procedure, coaptation is to themasseteric nerve, which is transected on the deep surface of the masseter within the mandibular notch. Movement is expected after 3 to 6 months for V toVII transfer, whereas 8 to 10months is requiredbeforemovement is seen for CFNG transfer ( Figure 5 A-D). Adverse outcomes following free gracilis transfer for smile re animation include failure to achieve dynamic smile (8%-30%), ex cessive facial bulk, incorrect vector of pull, activation with contra lateral blink with CFNG, and activation with mastication with V to VII transfer. When flap loss secondary to microvascular occlusion (<5%) is not the cause, failure is believed to result from inadequate ingrowth of the donor nerve fibers into the transferred muscle. Nerve Transfer to Native Facial Musculature | Nerve transfer to na tive facial musculature is possible in NFFP, where FN branches are anatomically intact and facial musculature is viable despite func tional immobility. An evolving technique in reanimation involves in terruption of native synkinetic FNbranches to the zygomaticusma jor with coaptation to a volitionally controllable input (eg, the ipsilateral masseteric branch of the trigeminal or CFNG) to restore meaningful smile. Commissure excursion in nerve transfer tech niques tonative facialmusculature is typically less than that achieved using freemuscle transfer, possibly due to residual synkinetic input to the muscle, disorganization of motor units, and focal dener vated adynamic areas within the synkinetic muscle. If axons fail to traverse the neurorrhaphy following nerve transfer, a risk of wors ening facial functionwith this approach exists. As discussed above, nerve transfer to selective distal intact branches (eg, to those con trolling smile or blink)may be performed acutely following segmen tal FN resection. Nerve transfer is also possible in select cases of FFP when no recovery of function is noted 9 to 12 months following in sult and inwhich the expected time from insult to transferred axons reaching the muscle is less than 18 to 24 months. Although precise identification of target muscle and force vectors by neural stimula tion is not possible in this setting, anatomic consistency of midfa cial branches makes nerve transfer a reasonable option with a high chance of success (Figure 5E-H). Lower Lip, Mentum, and Neck The lower lip and oral commissure are typically inferiorly malposi tioned in FFP, and correction may be obtained using static suspen sion or dynamic reanimation of smile. In NFFP, the lower lipmay be superiorlymalpositionedandhypomobile. Chemodenervationof the contralateral depressor labii inferiorismay help to improve facial bal ance in both FFP and NFFP. When this fails, resection may be ben eficial, and itmaybeaccomplished transorallyusing local anesthesia. 2

ducehollowing in the temporal region. Sequelaeof temporalis trans position include facial contour defects, temporal alopecia, and in adequate commissure excursion. Relative contraindications include temporalismuscledisuse atrophy secondary to an edentulous state, preoperative wasting, and trigeminal dysfunction. Nerve Transfer Donor nerves for transfer to free muscle or native facial muscula turemay include split hypoglossal (XII-VII), masseteric or deep tem poral branches of the trigeminal (V-VII), or cross-FNgrafting (CFNG) using an autologous long sural graft. The tonguemorbidity and syn kinesis of the hypoglossal-facial transfer has led to a decline in its popularity. AV to VII transfer using either themasseteric nerve 39 or deep temporal branches is increasing inpopularity secondary tomini mal donor-sitemorbidity, easeof volitional triggering comparedwith hypoglossal transfer, and superior commissure excursion com pared with CFNG due to higher motor neuron counts. 40 The benefits of CFNG for smile over other nerve transfer tech niques include reanimation of spontaneous (emotive) smile in ad dition to volitional smile, improved resting firing tone, and absence of facial twitching with mastication that may be seen with V to VII transfers. Disadvantages of CFNG include smile with less commis sure excursion, on average, than that obtained using other nerve transfers (eg, V-VII) due to fewer available motor axons 40 ; a risk of causing undesired weakness in healthy hemiface, ocular synkine sis, or blink-triggered activation (because some fibers to the orbicularis oculi are often present in the donormidface branch); the typical need for a staged second procedure; and increased risk of donor-sitemorbidity. The CFNGprocedure beginswith elevation of a sub-SMAS flap over the parotidomasseteric fascia using a preauricular incisionon thenonparalyzed side. Facial nervebranches yielding isolated smile are identified using monopolar nerve stimu lation, and 1 or 2 branches are then sharply transected depending on redundancy. Next, a long sural nerve graft is harvested and inset with its polarity reversed in a subcutaneous tunnel across the up per lip. When free muscle transfer is planned, the proximal end of the graft is banked deep to the gingivobuccal sulcus on the para lyzed side and tagged with a 4-0 nylon suture for later retrieval. A longer graft banked in the preauricular area is used when direct hookup to branches from the native facial musculature on the pa retic side is planned. Thedistal end is coapted to the transected smile branches using 10-0nylon sutures and fibringlue. Second-stagedis tal nerve graft coaptation to free or native facial musculature en sues once axonal growth across the graft is complete, as deter mined clinically by a positive Tinel sign, typically 6 to9months later. FreeGracilis Transfer | Patientswitha reasonable lifeexpectancywith out significant comorbidities are candidates for freemuscle transfer. Althoughuseof the rectus, 41 pectoralisminor, 42 and latissimusdorsi 43 muscleshasbeendescribed, thegracilis (firstdescribedbyHarii etal 44 ) remains themost popular choice for freemuscle transfer for smile re animation. Innervation isprovidedthrougheitheracross-facial orother nerve transfer, most commonly the ipsilateral masseteric branch of the trigeminal nerve. The gracilis muscle is harvested from the me dial aspect of the thigh through an incision 2 cmposterior and paral lel to a line connecting the pubic tubercle and the medial tibial con dyle. The belly of the gracilis muscle is identified, followed by the neurovascular pedicle that enters its deep surface 8 to 10 cm caudal

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298 JAMA Facial Plastic Surgery July/August 2015 Volume 17, Number 4 (Reprinted)

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