Hemihypoglossal-Facial Nerve Anastomosis for Facial Nerve Reanimation: Case Series and Technical Note

Hypoglossal Nerve Transfer for Facial Nerve Paralysis: A Systematic Review and Meta-Analysis

Background: Hypoglossal-facial nerve (12-7) anastomosis can restore symmetry and voluntary movement on the face in patients with facial nerve paralysis. Traditional 12-7 transfer includes direct end-to-end nerve anastomosis, sacrificing the entire hypoglossal nerve. Contemporary, end-to-side anastomosis, or split anastomosis techniques limit tongue morbidity by preserving some hypoglossal nerve. Direct outcome comparisons between these techniques are limited. Objective: To compare reported outcomes of facial movement, tongue, speech, and swallow outcomes among the different types of hypoglossal-facial nerve anastomosis schemes. Evidence Review: For this systematic review and meta-analysis, a comprehensive strategy was designed to search PubMed, Scopus, and the Cochrane Database from inception to January 2021, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis, reporting guideline yielding 383 results. Any participant who underwent 12-7 transfer using any of the three techniques, with or without an interposition graft, and had documented preoperative and postoperative evaluation of facial nerve function with a validated instrument such as House-Brackmann (HB), was considered for inclusion. Secondary outcomes of synkinesis, tongue atrophy, and speech or swallowing dysfunction were also compared. Forty-nine studies met inclusion criteria, representing data from 961 total patients who underwent 12-7 transfer. Results: The proportion of good HB outcomes (HB I-III) did not differ by anastomosis type: End-to-side and end-to-end anastomosis (73% vs. 59%, p = 0.07), split and end-to-end anastomosis (62% vs. 59%, p = 0.88), and end-to-side anastomosis and split anastomosis (73% vs. 62%, p = 0.46). There was no difference in reported synkinesis rates between the anastomosis types. However, end-to-side anastomosis (z = 6.55, p < 0.01) and split anastomosis (z = 3.58, p < 0.01) developed less tongue atrophy than end-to-end anastomosis. End-to-side anastomosis had less speech/swallowing dysfunction than end-to-end anastomosis (z = 3.21, p < 0.01). Conclusion: End-to-side and split anastomoses result in similar HB facial nerve outcomes as the traditional end-to-end 12-7 anastomosis. End-to-side anastomosis has decreased complications of tongue atrophy and speech/swallow dysfunction compared to end-to-end anastomosis. In addition, split anastomosis has decreased rates of tongue atrophy compared to end-to-end anastomosis.

Research status of facial nerve repair

The facial nerve, also known as the seventh cranial nerve, is critical in controlling the movement of the facial muscles. It is responsible for all facial expressions, such as smiling, frowning, and moving the eyebrows. However, damage to this nerve can occur for a variety of reasons, including maxillofacial surgery, trauma, tumors, and infections. Facial nerve injuries can cause severe functional impairment and can lead to different degrees of facial paralysis, significantly affecting the quality of life of patients. Over the past ten years, significant progress has been made in the field of facial nerve repair. Different approaches, including direct suture, autologous nerve grafts, and tissue engineering, have been utilized for the repair of facial nerve injury. This article mainly summarizes the clinical methods and basic research progress of facial nerve repair in the past ten years.

Feasibility of an endoscope-dominated side-to-end hypoglossal-facial anastomosis: an anatomical study

Objective

A surgical simulation of an endoscope-dominated side-to-end hypoglossal-facial anastomosis was performed to evaluate the feasibility.

Methods

Eight anatomical cadaver heads (16 sides) were recruited. The steps in conventional procedures were abbreviated or omitted. A facial nerve was first harvested near its external genu and was used for a side-to-end hypoglossal-facial anastomosis. The stump of the used facial nerve was truncated and recycled immediately caudal to the facial recess in another anastomosis and then recycled again at the stylomastoid foramen. As a recycled stump becomes too short to ensure a side-to-end anastomosis, the hypoglossal nerve was transected in situ, and an endoscopic end-to-end hypoglossal-facial anastomosis was attempted. Surgical simulation and quantitative measurement methods were used to analyze the anastomosis effects of different harvested sites of the facial nerve.

Results

Several steps in the conventional procedures provide little benefit in endoscopic surgery. A facial nerve stump recycled at the stylomastoid foramen is too short to ensure a tensionless side-to-end anastomosis. An endoscopic end-to-end hypoglossal-facial anastomosis was feasible, although it required more time than the classical microsurgical anastomosis. The greater agility of an endoscope enables the conventional surgical steps to be overlapped or interweaved into the procedure.

Conclusions

The multiple surgical fields and ability to manipulate the viewpoint provided by an endoscope have brought about breakthroughs in classical surgical paradigms. In addition, it is best to choose the sites of the facial nerve harvested near the external genu. If unavailable, an alternative section site could be selected immediately caudal to the facial recess, but cannot be distal to the stylomastoid foramen. The length of the stump should be individualized and preferably optimized with a nerve stimulator.

Contribution and safety of the side-to-end hypoglossal-to-facial transfer in multidisciplinary facial reanimation

BACKGROUND

This study evaluates facial and tongue function in patients undergoing side-to-end hypoglossal-to-facial transfer (HFT) with additional techniques.

METHODS

Thirty-seven patients underwent a side-to-end HFT. Twelve had additional cross-face grafts, and 9 had an additional masseter-to-facial transfer. Facial was assessed with House-Brackmann (HB), Sunnybrook Facial Grading Scale (SFGS), and eFACE. Martins scale and the Oral-Pharyngeal Disability Index (OPDI) were used to assess tongue function.

RESULTS

Ninety-four percent of cases reached HB grades III-IV. Mean total SFGS score improved from 16 ± 15 to 59 ± 11, while total eFACE score from 52 ± 13 to 80 ± 5. Dual nerve transfers were a predictor for a better eFACE total score p = 0.034, β = 2.350 [95% CI, 0.184-4.516]), as well as for a higher SFGS total score (p = 0.036, β = 5.412 [95% CI, 0.375-10.449]). All patients had Martin's grade I. Mean postoperative OPDI scores were 84 ± 17 (local physical), 69 ± 16 (simple and sensory motor components), 82 ± 14 (complex functions), and 73 ± 22 (psychosocial).

CONCLUSIONS

The side-to-end HFT offers predictable facial function outcome and preserves tongue function in nearly all cases. Dual nerve transfers appear to improve the final outcome.

End-to-Trunk Masseteric to Facial Nerve Transfer With Selective Neurectomy for Facial Reanimation

OBJECTIVE

To examine functional outcomes following end-to-trunk masseteric to facial nerve transfer in patients with chronic flaccid facial paralysis.

DESIGN

Retrospective chart review.

SETTING

Tertiary-care private practice setting.

PARTICIPANTS

Patients with complete unilateral facial paralysis of less than 24 months duration.

INTERVENTIONS

Direct end-to-trunk masseteric to facial nerve anastomosis.

OUTCOME MEASURES

Outcome measures included time to first movement, development of synkinesis, and an objective assessment of the resting tone and dynamic movement that was achieved.

RESULTS

Patient age at the time of transfer ranged from 6 to 61. Follow-up ranged from 12 to 24 months. No patients had any perioperative complications. No patient experienced significant mass movement or synkinetic facial movement with chewing. No patient had worsened chewing or swallowing. Patients have not yet recovered significant resting tone. All patients achieved smile activity when biting down with a median (interquartile range) oral commissure excursion of 7.57 mm (5.19-9.94 mm), starting 3 to 5 months after transfer.

CONCLUSIONS

End-to-trunk masseteric to facial nerve transfer is a safe and effective procedure. Patients had rapid reinnervation with good excursion and achieved a natural appearing smile. The rehabilitated smile appears better than that achieved with hypoglossal-facial nerve transfer. The procedure can be performed coincident with cross-facial nerve grafting, and in some cases may produce dynamic facial movement that obviates the need for free muscle transfer.

Clinical Studies and Pre-clinical Animal Models on Facial Nerve Preservation, Reconstruction, and Regeneration Following Cerebellopontine Angle Tumor Surgery-A Systematic Review and Future Perspectives

Background and purpose: Tumorous lesions developing in the cerebellopontine angle (CPA) get into close contact with the 1st (cisternal) and 2nd (meatal) intra-arachnoidal portion of the facial nerve (FN). When surgical damage occurs, commonly known reconstruction strategies are often associated with poor functional recovery. This article aims to provide a systematic overview for translational research by establishing the current evidence on available clinical studies and experimental models reporting on intracranial FN injury.

Methods: A systematic literature search of several databases (PubMed, EMBASE, Medline) was performed prior to July 2020. Suitable articles were selected based on predefined eligibility criteria following the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. Included clinical studies were reviewed and categorized according to the pathology and surgical resection strategy, and experimental studies according to the animal. For anatomical study purposes, perfusion-fixed adult New Zealand white rabbits were used for radiological high-resolution imaging and anatomical dissection of the CPA and periotic skull base.

Results: One hundred forty four out of 166 included publications were clinical studies reporting on FN outcomes after CPA-tumor surgery in 19,136 patients. During CPA-tumor surgery, the specific vulnerability of the intracranial FN to stretching and compression more likely leads to neurapraxia or axonotmesis than neurotmesis. Severe FN palsy was reported in 7 to 15 % after vestibular schwannoma surgery, and 6% following the resection of CPA-meningioma. Twenty-two papers reported on experimental studies, out of which only 6 specifically used intracranial FN injury in a rodent (n = 4) or non-rodent model (n = 2). Rats and rabbits offer a feasible model for manipulation of the FN in the CPA, the latter was further confirmed in our study covering the radiological and anatomical analysis of perfusion fixed periotic bones.

Conclusion: The particular anatomical and physiological features of the intracranial FN warrant a distinguishment of experimental models for intracranial FN injuries. New Zealand White rabbits might be a very cost-effective and valuable option to test new experimental approaches for intracranial FN regeneration. Flexible and bioactive biomaterials, commonly used in skull base surgery, endowed with trophic and topographical functions, should address the specific needs of intracranial FN injuries.

The Experience of a Facial Nerve Unit in the Treatment of Patients With Facial Paralysis Following Skull Base Surgery

: The management of facial paralysis following skull base surgery is complex and requires multidisciplinary intervention. This review shows the experience of a facial nerve (FN) unit in a tertiary university referral center. A multidisciplinary approach has led to the breaking of some old treatment paradigms. An overview of five FN scenarios is presented. For each setting a contemporary approach is proposed in contrast to the established approach. 1) For patients with an anatomically preserved FN with no electrical response at the end of surgery for vestibular schwannoma, watchful waiting is usually advocated. In these cases, reinforcement with an interposed nerve graft is recommended. 2) In cases of epineural FN repair, with or without grafting, and a poor expected prognosis, an additional masseter-to-facial transfer is recommended. 3) FN transfer, mainly hypoglossal-to-facial and masseter-to facial, are usually chosen based on the surgeons' preference. The choice should be based on clinical factors. A combination of techniques improves the outcome in selected patients. 4) FN reconstruction following malignant tumors requires a combination of parotid and temporal bone surgery, involving different specialists. This collaboration is not always consistent. Exposure of the mastoid FN is recommended for lesions involving the stylomastoid foramen, as well as intraoperative FN reconstruction. 5) In patients with incomplete facial paralysis and a skull base tumor requiring additional surgery, consider an alternative reinnervation procedure, "take the FN out of the equation" before tumor resection. In summary, to achieve the best results in complex cases of facial paralysis, a multidisciplinary approach is recommended.

Assessment of eye closure and blink with facial palsy: A systematic literature review

Facial palsy can cause the impairment of eye closure and affect blink, ocular health, communication, and esthetics. Dynamic surgical procedures can restore eye closure in patients with decreased facial nerve function. There are no standardized measures of voluntary and spontaneous eye closure that are used to evaluate the outcomes of blink restoration procedures. The purpose of this systematic literature review was to identify the measures used to assess normal and abnormal eye closure and blinking in patients with facial palsy. A literature search of the PubMed database using the keyword "facial nerve/surgery" was conducted. Only English language articles that pertain to the use of facial paralysis assessment systems published in the past 20 years, which involve eyelid closure were included. There were 57 articles that used a facial paralysis classification system with an eyelid closure component: House-Brackmann Facial Nerve Grading Scale (n = 43, 67%); Sunnybrook Facial Grading Scale (n = 9); palpebral fissure heights (n = 4), and the electronic clinician-graded facial function tool (n = 3) and three additional measures were reported once. Although the Terzis and Bruno Scoring System, blink ratio, and electronic, clinician-graded facial function scale(eFACE) Clinician-Graded Scoring System were valid measures of eyelid closure, there was no one comprehensive eye assessment that demonstrated all aspects of eye closure in facial palsy, which include closure amplitude, spontaneity, and quality of life. For blink assessment, eFACE is the most comprehensive tool currently available and recommended to be used with a patient-reported quality of life supplement that captures the specific domains related to facial nerve dysfunction.

Hypoglossal and Masseteric Nerve Transfer for Facial Reanimation: A Systematic Review and Meta-Analysis

Background: Hypoglossal and masseteric nerve transfer are currently the most popular cranial nerve transfer techniques for patients with facial paralysis. The authors performed a systematic review and meta-analysis to compare functional outcomes and adverse effects of these procedures. Methods: A review of online databases was performed to include studies with four or more patients undergoing hypoglossal or masseter nerve transfer without muscle transfer or other cranial nerve transposition. Facial nerve outcomes, time to reinnervation, and adverse events were pooled and studied. Results: A total of 71 studies were included: 15 studies included 220 masseteric-facial transfers, and 60 studies included 1312 hypoglossal-facial transfers. Oral commissure symmetry at rest was better for hypoglossal transfer (2.22 ± 1.6 mm vs. 3.62 ± 2.7 mm, p = 0.047). The composite Sunnybrook Facial Nerve Grading Scale was better for masseteric transfer (47.7 ± 7.4 vs. 33.0 ± 6.4, p < 0.001). Time to first movement (in months) was significantly faster in masseteric transfer (4.6 ± 2.6 vs. 6.3 ± 1.3, p < 0.001). Adverse effects were rare (<5%) for both procedures. Conclusions: Both nerve transfer techniques are effective for facial reanimation, and the surgeon should consider the nuanced differences in selecting the correct procedure for each patient.

Surgery After Surgery for Vestibular Schwannoma: A Case Series

Objective

We retrospectively evaluated the oncological and functional effectiveness of revision surgery for recurrent or remnant vestibular schwannoma (rVS).

Methods

We included 29 consecutive patients with unilateral hearing loss (16 women; mean age: 42.2 years) that underwent surgery for rVS. Previous surgeries included gross total resections (GTRs, n=11) or subtotal resections (n=18); mean times to recurrence were 9.45 and 4.15 years, respectively. House–Brackmann (HB) grading of facial nerve (FN) weakness (grades II-IV) indicated that 22 (75.9%) patients had deep, long-lasting FN paresis (HB grades: IV-VI). The mean recurrent tumor size was 23.3 mm (range: 6 to 51). Seven patients had neurofibromatosis type 2.

Results

All patients received revision GTRs. Fourteen small- to medium-sized tumors located at the bottom of the internal acoustic canal required the translabyrinthine approach (TLA); 12 large and small tumors, predominantly in the cerebellopontine angle, required the retrosigmoid approach (RSA); and 2 required both TLA and RSA. One tumor that progressed to the petrous apex required the middle fossa approach. Fifteen patients underwent facial neurorrhaphy. Of these, 11 received hemihypoglossal–facial neurorrhaphies (HHFNs); nine with simultaneous revision surgery. In follow-up, 10 patients (34.48%) experienced persistent deep FN paresis (HB grades IV-VI). After HHFN, all patients improved from HB grade VI to III (n=10) or IV (n=1). No tumors recurred during follow-up (mean, 3.46 years).

Conclusions

Aggressive microsurgical rVS treatment combined with FN reconstruction provided durable oncological and neurological effects. Surgery was a reasonable alternative to radiosurgery, particularly in facial neurorrhaphy, where it provided a one-step treatment.

Comparison between VII-to-VII and XII-to-VII coaptation techniques for early facial nerve reanimation after surgical intra-cranial injuries: a systematic review and pooled analysis of the functional outcomes

The surgical injury of the intracranial portion of the facial nerve (FN) is a severe complication of many skull base procedures, and it represents a relevant issue in terms of patients' discomfort, social interactions, risk for depression, and social costs. The aim of this study was to investigate the surgical and functional outcomes of the most common facial nerve rehabilitation techniques. The present study is a systematic review of the pertinent literature, according to the PRISMA guidelines. Two different online medical databases (PubMed, Scopus) were screened for studies reporting the functional outcome, measured by the House-Brackman (HB) scale, and complications, in FN early reanimation, following surgical injuries on its intracranial portion. Data on the VII-to-VII and XII-to-VII coaptation, the surgical technique, the use of a nerve graft, the duration of the deficit, and complications were collected and pooled. The XII-to-VII end-to-side coaptation seems to provide higher chances for functional restoration (HB 1-3) than the VII-to-VII (68.8% vs 60.6%), regardless of the duration of the palsy deficit, the use or not of a nerve graft, and the use of stitches or glues. However, its complication rate was as high as 28.6%, and a second procedure is then often needed. The XII-to-VII side-to-end coaptation is the most effective in providing a functional outcome (HB 1-3), even though it is associated to a higher complication rate. Further trials are needed to better investigate this relevant topic, in terms of health-related social costs and patients' quality of life.