Cross-face Nerve Research Articles

Contemporary techniques for nerve transfer in facial reanimation

Nerve transfer procedures have the potential to restore innervation and function to the native facial musculature. This review summarizes the existing literature on facial nerve injury, regeneration, and reinnervation techniques with a focus on nerve transfer and its various options. Utilizing nerve transfer as early as possible, and ideally during the first 12 months of paralysis, is recommended. Prolonged paralysis is frequently not amenable to nerve transfer. The masseteric nerve provides excellent smile restoration after coapation to midfacial nerve branches with minimal morbidity. Several modifications to the hypoglossal nerve transfer have been described to limit its morbidity in speech and swallowing. The cross facial nerve, while appealing and able to achieve a true spontaneous smile, has limitations in terms of axonal load, time to reinnervation, unpredictable outcomes, and utility in older patients, who have less regenerative potential. Finally, there are exciting new developments in the field, combining reanimation techniques to harness advantages of various donor nerves, and research in peripheral nerve regeneration.

The Multivector Gracilis Free Functional Muscle Flap for Facial Reanimation.

A multivector functional muscle flap that closely simulates the biomechanical effects of facial muscle groups is essential for complete smile restoration after facial paralysis. To determine the feasibility of a multivector gracilis muscle flap design for reanimation after facial paralysis and to analyze the effect on the smile display zone. Prospective analysis of patients who underwent a double paddle multivector gracilis flap for complete facial paralysis between June 2015 and December 2016 was carried out in a tertiary hospital. The gracilis muscle was harvested as a double paddle flap and inserted along 2 vectors for facial reanimation. The primary outcome measures were: (1) dental display (the number of maxillary teeth displayed on paralyzed vs normal sides), (2) exposed maxillary gingival scaffold width, (3) interlabial gap at midline and canine, (4) facial asymmetry index (FAI), and (5) dynamic periorbital wrinkling. There were 10 women and 2 men between ages 20 and 64 years (mean [SD], 46 [15] years). Five flaps were reinnervated with facial and masseteric nerves, 5 with masseteric nerve only, and 2 with crossfacial nerve only. There was functional muscle recovery in all cases. On average there was additional 3.1 maxillary teeth exposed posttreatment when smiling (5.5 vs 8.6; CI, 7.9 to 16.6; P < .001). The mean exposed maxillary gingival scaffold width improved from 31.5 mm to 43.7 mm (95% CI, 1.9 to 4.3; P < .001). There was no significant difference in interlabial exposure at midline (7.1 mm vs 7.7 mm; CI, -1.5 to 2.7; P = .56) but a 56.4% improvement at the level of the canines (3.9 vs 6.1; CI, 0.1 to 4.3; P = .04). The mean FAI when smiling was reduced from 9.1 mm to 4.5 mm (CI, -8.0 to -1.2; P = .01). Dynamic wrinkling of the periorbital area with smiling was noted in 4 patients. The gracilis flap can be reliably designed as a functional double paddle muscle flap for a multivector facial reanimation. The multivector gracilis flap design is effective in improving all components of the smile display zone and has the potential for producing periorbital-wrinkling characteristic of a Duchenne smile. 4.

Stereophotogrammetric assessment of the smiling capability after facial reanimation surgery

Facial palsy causes functional and aesthetic problems; among those, the reduction of facial mimicry and smiling difficulties, require surgical treatment and rehabilitative procedures [1]. To quantitatively evaluate the recovery of the smiling capabilities after reanimation surgery (double cross-face, masseteric-facial nerve neurorraphy, hypoglossus-facial nerve neurorraphy), 11 patients (4 females, 7 males, mean age 59.6, SD 10.4 years) affected by acute unilateral facial palsy were acquired with a 3D stereophotogrammetric instrument. Each patient was acquired in neutral facial position and performing 4 different types of smile, executed taking advantage of the aforementioned surgical stimuli, both separately and together. The smiling facial images were divided in two hemifaces, successively registered on the corresponding neutral one. Root Mean Square (RMS) distances between neutral face and smiling hemifaces were automatically calculated by the software of the stereophotogrametric system. Inter and intra-operator repeatability in performing this procedure were assessed. A two-way ANOVA for repeated measurements was performed in order to verify the differences among the smiles and the facial sides. Results showed good intra and inter operator repeatability of the procedures (R2 0.6 and 0.9, respectively). Statistical significant differences were found among the different smiles and the facial sides (p < 0.01 in both cases) and for the side x smile interaction (p < 0.05). For the affected facial side, post hoc tests revealed statistical significant differences (p < 0.05) between the smiles performed using the double cross-face (mean RMS 0.5 ± 0.2 mm) and masseteric-facial nerve neurorraphy, with this last being more powerful (RMS 0.9 ± 0.5 mm). The results offer the possibility to objectively quantify the recovery of the smiling capability, usually qualitatively evaluated, through subjective grading systems.

Long-Term Outcomes of Free-Muscle Transfer for Smile Restoration in Adults

The cross-facial nerve grafting/free-muscle transfer strategy for smile restoration is superior to static reconstruction or regional muscle transposition. The purpose of this study was to evaluate the long-term outcomes of this technique in adult patients. Eighty-one adult patients received a free-muscle transfer for midface reanimation in the authors' center. Of this group, the authors identified 24 cases with follow-up of 5 years or longer. Smile symmetry and function were evaluated at three points: preoperatively, early postoperatively, and at long-term follow-up. To better evaluate the effect of time, patients were divided into groups according to the length of follow-up: group A, 5 to 6 years; group B, 7 to 10 years; group C, 11 to 15 years; and group D, more than 15 years. Four independent observers rated each patient's smile using a five-category scale ranging from poor to excellent. Panelists were asked to comment on whether the patient's smile weakened over time. All patients obtained higher scores at 2 years from free-muscle transfer in comparison with their preoperative rates (p < 0.0001). Late outcomes demonstrated that muscle regeneration continues beyond the initial 2 years, with a further increase of the scores and motor units on electromyography at the late follow-up (p < 0.0001, p = 0.0313). No significance was found when comparing both variables among the four groups, indicating that time does not have a differential effect on muscle function. In 80 percent of the evaluations, the four observers agreed on maintained smile symmetry over time. Cross-facial nerve grafting/free-muscle transfer is an effective technique for smile restoration in late facial paralysis. These data indicate maintenance of effective muscle function and progressive improvement with time.