A comparison of one- versus two-stage surgery in an experimental model of functional muscle transfer with interposed nerve grafting

Cross-Facial Nerve Grafting Used Independently in Facial Reanimation: A Narrative Review

Importance: Cross-Facial Nerve Grafting (CFNG) for facial palsy offers potential to restore spontaneous facial expression, but specific indications and associated outcomes are limited. Updates to this technique have aided in its successful employment in select cases. This review aims to explore the context in which CFNG has been successfully utilized as a primary modality. Observations: Literature review was performed auditing all studies investigating CFNG as a primary modality, which reported outcomes. A total of 326 cases reporting outcomes for primary CFNG were included. Eye closure outcomes were 83.3% successful at ages 0-18, 77.3% successful at ages 19-40, and 57.1% successful at ages 41+. Smile outcomes were 73.7% successful at ages 0-18, 81.5% successful at ages 19-40, and 52.8% successful at ages 41+. For synkinesis, 89% of cases were considered successful; 100% successful at ages 0-18, and 78.4% successful in adults. Conclusions and Relevance: CFNG may offer return of spontaneous facial function in select cases. Higher percentages of successful outcomes are observed in younger patients, when performed in two stages, and when performed earlier from the onset of FP in cases of eye closure restoration. In the modern era, CFNG has been more commonly employed as an adjunctive procedure to other reanimation techniques.

Age-related outcomes of facial reanimation surgery using gracilis free functional muscle transfer innervated by the masseteric nerve: A retrospective cohort study

BACKGROUND

The free functional muscle gracilis transfer is an established approach in facial reanimation surgery; however, the significance of its neurotization and the patient's age is still inconclusive. Several donor nerves are available for facial reanimation using the free functional gracilis muscle transfer.

OBJECTIVE

This retrospective cohort study investigates whether the masseteric nerve is an equally reliable donor nerve in both older and younger patients.

METHODS

We included 46 patients (13-71 years, male and female) who underwent nerve-to-masseter (NTM)-driven free functional muscle transfer (FFMT) between January 2008 and December 2019. Patients were distributed into three cohorts according to their age at surgery. We assessed the facial symmetry before and after surgery using the pupillo-modiolar angle. Commissure height and excursion deviation were measured with the Emotrics software. Patient-reported outcome measurements were taken using the Facial Clinimetric Examination (FaCE) scale.

RESULTS

All patients had successful flap innervation, except for one patient in the middle-aged cohort (31-51 years). The postoperative facial symmetry at rest, smiling, and laughing was analyzed with the pupillo-modiolar angle and the Emotrics software and showed similar results between all cohorts. The FaCE scale showed similar scores for the middle-aged (31-51 years) cohort and the senior cohort (52-71 years). The social function score in the senior cohort was higher than in the middle-aged cohort, without statistical significance. One patient in the middle-aged (31-51 years) cohort and the senior cohort (52-71 years), respectively, underwent emergency revision due to impaired flap perfusion and could be salvaged.

CONCLUSIONS

NTM-driven FFMT for facial reanimation is a safe and reliable procedure across all age groups of patients.

Comparison of static and dynamic symmetry between masseter-innervated and dual-innervated free multivector serratus anterior muscle transfer for complete facial paralysis

PURPOSE

In this study, facial symmetry was compared between the masseter-innervated and dual-innervated free multivector serratus anterior muscle transfer (FMSAMT) methods.

METHODS

Eighteen patients with unilateral complete facial paralysis underwent facial reanimation surgery between April 2006 and July 2019. The masseter-innervated FMSAMT group (Group M, n = 8) underwent end-to-end coaptation with the ipsilateral masseter nerve in one stage. The dual-innervated FMSAMT group (Group D, n = 10) underwent end-to-end coaptation with the masseter nerve and end-to-side coaptation with the contralateral facial nerve via cross-face nerve graft. They were further divided into the one-stage (Group D1, n = 5) and two-stage (Group D2, n = 5) subgroups. The durations of periods until the first visible muscle contraction with clenching, first spontaneous smile, and the completion of resting tone were evaluated. The possibility of a spontaneous smile and symmetry of the midline and horizontal deviation at rest and during voluntary smiling were compared between each group.

RESULTS

Groups M and D differed significantly in the possibility of a spontaneous smile and improvement rate of midline deviation and horizontal deviation at rest (p < 0.001, p < 0.001, and p = 0.001, respectively) but not in the improvement rate of midline and horizontal deviation during voluntary smiling. The duration of the period until the completion of resting tone was significantly shorter in Group D1 than in Group D2 (p = 0.048); however, the possibility of a spontaneous smile and the improvement rate of midline and horizontal deviation were not significantly different.

CONCLUSIONS

Dual-innervated FMSAMT was effective in guaranteeing a symmetrical resting tone, voluntary smiling, and reproducing a spontaneous smile.

Neuromuscular reinnervation efficacy using a YFP model

INTRODUCTION

The gold standard reconstruction for facial reanimation is the functional muscle transfer. The reinnervation of a muscle is never complete, and clinical results are variable with 20% not achieving a satisfactory outcome. We hypothesise that this may be due to a mismatch between the characteristics of the donor nerve and transferred muscle.

METHOD

81 YFP-16 and 14 YFP-H mice were studied in three intervention groups over three time periods. Two parameters were investigated: the number and surface area of reinnervated neuromuscular junctions and regenerating axons. An assessment was made of motor unit proportions.

RESULTS

All cases of nerve repair and nerve graft, the neuromuscular junctions (NMJ) were completely reinnervated by regenerating axons. The number and calibre of the regenerating axons were significantly different from controls for both intervention groups. The motor units were smaller in both intervention groups.

DISCUSSION

Reinnervation occurs after nerve repair or graft; however, the arbour was reinnervated by large numbers of much smaller axons. These axons showed some evidence of remodelling in the repair group, but not in the graft group. Neither group achieved the parameters of the control group. There were persistent qualitative changes to the morphology of both axons and junctions. Imaging documented both synkinesis and alterations that resemble those seen in ageing.

CONCLUSION

Overall, the efficacy of reinnervation is very high with all NMJ reoccupied by regenerating axons. The way small axons are remodelled is different in the nerve repairs compared with the nerve grafts.

Single-stage cross-facial nerve grafting has a result equivalent to that of two-stage cross-facial nerve grafting

BACKGROUNDS

Cross-face nerve grafting (CFNG) is an important treatment for patients with facial palsy. Currently, two-stage CFNG is frequently performed. CFNG is performed first, followed by coaptation when innervation reaches the grafted nerve ending. The present study compared single-stage CFNG with conventional two-stage CFNG.

METHODS

We retrospectively reviewed data of 17 patients who underwent CFNG with zygomatic and buccal branch with hypoglossal crossover. Patients with single-stage (group 1) and two-stage (group 2) CFNG were comparatively analyzed 2 years postoperatively. There were nine and eight patients in groups 1 and 2, respectively. The patient's perioperative status was measured with imaging and animation using the Yanagihara grade, altitude, and angle differences of the oral commissure and eye closure.

RESULTS

Patients in group 1 could recognize their first postoperative spontaneous movement earlier than those in group 2 (268.3 ± 25.1 days vs. 327.5 ± 51.3 days, respectively, p = 0.015). The Yanagihara grade significantly improved for patients in both groups postoperatively (group 1: 12.8 ± 5.5 to 25.3 ± 6.1, p < 0.01; group 2: 12.4 ± 5.6 to 24.3 ± 5.0, p = 0.012). Height and angle difference of the oral commissure showed a significant improvement during resting and smiling in both groups. Eye closure also showed significant improvement in both groups (group 1: 4.1 ± 0.6 to 2.6 ± 0.5, p < 0.01; group 2: 4.0 ± 0.5 to 2.8 ± 0.7, p < 0.01). There was no significant difference in the postoperative improvement rate between the groups.

CONCLUSIONS

Single-stage CFNG shows results equivalent to those of two-stage CFNG. Single-stage CFNG is associated with a shorter treatment period and fewer operations.

Controversies in Contemporary Facial Reanimation

Facial palsy is a devastating condition with profound functional, aesthetic, and psychosocial implications. Although the complexity of facial expression and intricate synergy of facial mimetic muscles are difficult to restore, the goal of management is to reestablish facial symmetry and movement. Facial reanimation surgery requires an individualized treatment approach based on the cause, pattern, and duration of facial palsy while considering patient age, comorbidities, motivation, and goals. Contemporary reconstructive options include a spectrum of static and dynamic procedures. Controversies in the evaluation of patients with facial palsy, timing of intervention, and management decisions for dynamic smile reanimation are discussed.

Use of the interposed nerve graft to reduce differences in functional muscle transfer outcome arising from variability in motor input

Regulation of functional muscle transfer outcome by means of an interposed nerve graft: The gold standard treatment of chronic unilateral facial palsy is a functional muscle transfer (FMT) reinnervated by a branch of the contralateral facial nerve via a cross-facial nerve graft, but clinical outcome varies from underactivity to overactivity of the transferred muscle. Work in an animal model has established that the magnitude of donor motor input received by heterotopically transferred muscle correlates with reinnervation and force production, the corollary being that standardising donor motor input could standardise outcome. We hypothesise that a 'low-capacity' interposed nerve graft could deliver a fixed motor input to an FMT despite variable motor input, thereby standardising force production and clinical outcome. To test this hypothesis, we compared reinnervation and force production by FMTs reinnervated with different-sized motor inputs via high- and low-capacity interposed nerve grafts. Force production was measured in vivo after recovery of transplanted muscle, and reinnervation quantified by both nerve morphometry and intramuscular immunohistochemical staining for protein gene product 9.5. Both reinnervation and force production data suggest that outcome correlates with donor motor nerve magnitude only when a high-capacity interposed nerve graft is used, this correlation being lost when using a low-capacity interposed nerve graft. The implications for human facial reanimation surgery are discussed.

Reanimation of the middle and lower face in facial paralysis: review of the literature and personal approach

Facial paralysis refers to a condition in which all or portions of the facial nerve are paralysed. The facial nerve controls the muscles of facial expression, paralysis which results in a lack of facial expression which is not only an aesthetic issue, but has functional consequences as the patient cannot communicate effectively. The treatment of long-standing facial paralysis has challenged plastic surgeons for centuries, and still the ultimate goal of normality of the paralysed hemi-face with symmetry at rest as well as the generation of a spontaneous symmetrical smile with corneal protection has not yet fully been reached. Until the end of the 19th century, the treatment of this condition involved non-surgical means such as ointments, medicines and electrotherapy. With the advent and refinement of microvascular surgical techniques in the latter half of the 20th century, vascularised free muscle transfers coupled with cross-facial nerve grafts were introduced, allowing the possibility of spontaneous emotion being restored to the paralysed face became reality. The aim of this article is to revisit the surgical evolution and current options available as well as outcomes for patients suffering from facial paralysis concentrating on middle and lower face reanimation.