Causes and management of facial nerve palsy

Ophthalmic Assessment and Management in Acute Facial Palsy

This article aims to provide insights into emerging concepts in ophthalmic manifestations in patients with facial palsy and discusses considerations used to develop patient-specific management plans in acute management.

Delayed repair of the facial nerve and its negative impacts on nerve and muscle regeneration

Background

In this experimental protocol, we evaluated the immediate and delayed repair of the buccal branch of the facial nerve (BBFN) with heterologous fibrin biopolymer (HFB) as a coaptation medium and the use of photobiomodulation (PBM), performing functional and histomorphometric analysis of the BBFN and perioral muscles.

Methods

Twenty-eight rats were divided into eight groups using the BBFN bilaterally (the left nerve was used for PBM), namely: G1 - control group, right BBFN (without injury); G2 - control group, left BBFN (without injury + PBM); G3 - Denervated right BBFN (neurotmesis); G4 - Denervated left BBFN (neurotmesis + PBM); G5 - Immediate repair of right BBFN (neurotmesis + HFB); G6 - Immediate repair of left BBFN (neurotmesis + HFB + PBM); G7 - Delayed repair of right BBFN (neurotmesis + HFB); G8 - Delayed repair of left BBFN (neurotmesis + HFB + PBM). Delayed repair occurred after two weeks of denervation. All animals were sacrificed after six weeks postoperatively.

Results

In the parameters of the BBFN, we observed inferior results in the groups with delayed repair, in relation to the groups with immediate repair, with a significant difference (p < 0.05) in the diameter of the nerve fiber, the axon, and the thickness of the myelin sheath of the group with immediate repair with PBM compared to the other experimental groups. In measuring the muscle fiber area, groups G7 (826.4 ± 69.90) and G8 (836.7 ± 96.44) were similar to G5 (882.8 ± 70.51). In the functional analysis, the G7 (4.10 ± 0.07) and G8 (4.12 ± 0.08) groups presented normal parameters.

Conclusion

We demonstrated that delayed repair of BBFN is possible with HFB, but with worse results compared to immediate repair, and that PBM has a positive influence on nerve regeneration results in immediate repair.

Bone marrow stem cells with or without superparamagnetic iron oxide nanoparticles as a magnetic targeting tool: Which is better in regeneration of neurolysed facial nerve? An experimental study

Aim

This study was performed to evaluate neural regenerative capacities of bone marrow stem cells (BMSCs) with or without superparamagnetic iron oxide nanoparticles (SPIONs) as a magnetic targeting tool after neurolysis of the facial nerve (FN) in albino rats.

Methods

Thirty-eight male albino rats were selected. Two of them were euthanized for normal FN histology assessment. Thirty-six rats were injected with ethanol in the FN nerve for neurolysis induction and assessed one week post-operatively by eye blinking test. Animals were divided into three groups, each containing twelve rats: Group I (positive control) was injected with Dulbecco Modified Eagle's medium (DMEM-F12), group II was injected with BMSCs in DMEM-F12, and group III was injected with BMSCs in DMEM-F12 with poly l-lysine coated SPIONs (0.5 mmol/mL). Monitoring of SPIONs in the rat's body was carried out by MRI. A circular neodymium magnet N52 (0.57 T, 2 × 5 mm) was placed on each rat in group III just below the right ear at the site of surgery to attract SPIONs labeled BMSCs, left in place for 24 h, and then removed. From each group, six rats were euthanized at the end of the 4th and 8th week of treatment, respectively. The right FN trunks were extracted for routine histological examination using H&E stain. Immunohistochemical examination by anti-S100B was performed to characterize the thickness of the myelin sheath formed by the Schwann cells. Ultra-structural examination was performed to study changes in axons, myelin sheaths, and Schwann cells.

Results

Regeneration of nerve fibers, Schwan cells, and myelin sheaths was better in group II than in groups I and III histologically, immunohistochemically, and ultra-structurally.

Conclusion

BMSCs alone could ameliorate FN regeneration better than magnetic targeting treatment using BMSCs labeled with SPIONs.

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.

Biodegradable Nerve Guide with Glial Cell Line-Derived Neurotrophic Factor Improves Recovery After Facial Nerve Injury in Rats

Background: Bioengineered nerve guides with glial cell line-derived neurotrophic factor (GDNF) support recovery after facial nerve injury by acting as regenerative scaffolds. Objective: To compare functional, electrophysiological, and histological outcomes after repair of rat facial nerve transection in control, empty nerve guide, and nerve guide with GDNF conditions. Methods: Rats underwent transection and primary repair of the buccal branch of the facial nerve and were divided into (1) transection and repair only, (2) transection and repair augmented with empty guide, (3) transection and repair augmented with GDNF-guide groups. Weekly measurements of the whisking movements were recorded. At 12 weeks, compound muscle action potentials (CMAPs) at the whisker pad were assessed, and samples were collected for histomorphometric analysis. Results: Rats in GDNF-guide group displayed the earliest peak in normalized whisking amplitude. CMAPs were significantly higher after GDNF-guide placement. Mean fiber surface area of the target muscle, axonal count of the injured branch, and the number of Schwann cells were highest with GDNF guides. Conclusion: The biodegradable nerve guide containing double-walled GDNF microspheres enhanced recovery after facial nerve transection and primary repair.

Sunshine duration and solar radiation contributed to severe Bell's palsy: An 11-year time series analysis based on a distributed lag non-linear model model

Although previous studies have suggested that meteorological factors are associated with Bell's palsy, articles on this topic are rare and the results are inconsistent. We aim to reveal the relationship between exposure to different meteorological factors and the onset of severe Bell's palsy (SBP) with daily data. A case-crossover study based on time-series data was applied, and the minimum risk value of each climatic factor was set as the reference value. We fitted a distributed lag non-linear model (DLNM) which applied quasi-Poisson regression to evaluate the exposure-response association and the lag-response association of meteorological factors on the occurrence of SBP. The mode value and per-decile interval value of each meteorological factor were all included in the analysis. Sensitivity analyses were conducted to test the robustness of results. A total of 863 SBP patients (474 males and 389 females) from 7 hospitals in the Shenzhen Futian District were selected from January 2009 to February 2020. The highest relations effect was tested in the cumulative exposure-response result shown as follows; mean temperature at the minimum value 15.3°C with RR of 10.370 (1.557-69.077) over lag 0 to 13; relative humidity at the 30th value 71% with RR of 8.041 (1.016-63.616) over lag 0 to 14; wind speed at the 90th value 31 (0.1 m/s) with RR of 1.286 (1.038-1.593) over lag 0; mean air pressure at the 30th value 1001.4 (pa) with RR of 9.052 (1.039-78.858) over lag 0 to 5; visibility at the 80th value 26.5 (km) with RR of 1.961 (1.005-1.423) over lag 0 to 2; average total cloud cover at the max value 100 (%) with RR 1.787 (1.014-3.148) over lag 0 to 2; sunshine duration at the 10th value 0.1 (h) with RR of 4.772 (1.018-22.361); daily evaporation shows no relationship in the cumulative result; daily average solar radiation at the minimum value 0 (W/m2) with RR of 5.588 (1.184-26.382). There is a relationship between wind speed and the onset of SBP, while mean air pressure, visibility, and average total cloud cover, especially sunshine duration and solar radiation which showed a strong effect, may be associated with severe clinical symptoms of SBP. Mean temperature and relative humidity may affect the course of SBP.

Morphofunctional Improvement of the Facial Nerve and Muscles with Repair Using Heterologous Fibrin Biopolymer and Photobiomodulation

Peripheral nerve injuries impair the patient's functional capacity, including those occurring in the facial nerve, which require effective medical treatment. Thus, we investigated the use of heterologous fibrin biopolymer (HFB) in the repair of the buccal branch of the facial nerve (BBFN) associated with photobiomodulation (PBM), using a low-level laser (LLLT), analyzing the effects on axons, muscles facials, and functional recovery. This experimental study used twenty-one rats randomly divided into three groups of seven animals, using the BBFN bilaterally (the left nerve was used for LLLT): Control group-normal and laser (CGn and CGl); Denervated group-normal and laser (DGn and DGl); Experimental Repair Group-normal and laser (ERGn and ERGl). The photobiomodulation protocol began in the immediate postoperative period and continued for 5 weeks with a weekly application. After 6 weeks of the experiment, the BBFN and the perioral muscles were collected. A significant difference (p < 0.05) was observed in nerve fiber diameter (7.10 ± 0.25 µm and 8.00 ± 0.36 µm, respectively) and axon diameter (3.31 ± 0.19 µm and 4.07 ± 0.27 µm, respectively) between ERGn and ERGl. In the area of muscle fibers, ERGl was similar to GC. In the functional analysis, the ERGn and the ERGI (4.38 ± 0.10) and the ERGI (4.56 ± 0.11) showed parameters of normality. We show that HFB and PBM had positive effects on the morphological and functional stimulation of the buccal branch of the facial nerve, being an alternative and favorable for the regeneration of severe injuries.

Ocular and Palpebral Manifestations of Facial Palsy: An Epidemiologic Descriptive Study

Purpose

We describe the ocular and periocular clinical features in patients with a facial palsy diagnosis of any etiology and to report the demographics, relevant medical history and treatment modalities in these patients.

Patients and Methods

Retrospective and descriptive observational study. A total of 60 patients with a facial palsy diagnosis in the last 5 years were recruited from an ophthalmological clinic in northeastern Mexico. Demographic data, such as age, sex, disease evolution and etiology, visual acuity, ocular symptoms and ocular and periocular clinical features were obtained. Personal history of previous ophthalmologic surgery, as well as ocular and systemic diseases, were also recorded. Finally, a comparative analysis was done to determine association between signs, symptoms and treatment modalities.

Results

A prevalence of 0.14% was reported, 56.7% of patients were female, and mean age of presentation was 55.63±17.2 years. 76.7% of facial palsy was idiopathic in origin, followed by vascular disease in 8.30% and iatrogenic in 6.70%. 40% of patients had a history of arterial hypertension, 36.3% were diabetic, and 6.70% had cerebrovascular disease.

Conclusion

Early diagnosis of facial palsy is crucial in establishing an effective treatment plan and avoiding complications. The impact of this disease in patients' quality of life cannot be overlooked, and steps should be taken to address the different impairments that this ailment entails.

Acute Facial Nerve Palsy in Facial Nerve Schwannoma Following COVID-19 Infection

Lower motor neuron facial nerve palsy (FNP) has many causes. Bell's palsy is by far the commonest cause. Among other causes include infective and neoplastic causes. While FNP caused by facial nerve schwannoma (FNS); a benign neoplastic condition of the facial nerve is slowly progressing, infective causes mainly viral origins present with acute FNP. We present a young female who complained of an acute onset of FNP on day five of her COVID-19 infection. She initially presented with symptoms suggestive of ear infection, and subsequent magnetic resonance imaging (MRI) showed evidence of FNS, which she was subjected to surgery later at our center. This rare acute incidence of FNP in schwannoma might be triggered by the COVID-19 infection and demonstrates the role of imaging in finding the cause of FNP.

Incidence, Aetiology, and Associated Fracture Patterns of Infraorbital Nerve Injuries Following Zygomaticomaxillary Complex Fractures: A Retrospective Analysis of 272 Patients

STUDY DESIGN

Retrospective study.

OBJECTIVE

Zygomaticomaxillary complex (ZMC) fractures are common facial injuries with heterogeneity regarding aetiologies, fracture types, infraorbital nerve (ION) involvement, and treatment methods. The aim of this study was to identify associations between aetiologies, fracture types, and neurological complications. Additionally, treatment methods and recovery time were investigated.

METHODS

Medical files of 272 patients with unilateral and bilateral ZMC fractures were reviewed, whose cases were managed from January 2014 to January 2019 at the Department of Oral and Maxillofacial Surgery, University hospitals Leuven, Belgium. History of ION sensory dysfunction and facial nerve motoric dysfunction were noted during follow-up.

RESULTS

ION hypoaesthesia incidence was 37.3%, with the main causes being fall accidents, road traffic accidents, and interpersonal violence. Significant predictors of ION hypoaesthesia were Zingg type B fractures (P = 0.003), fracture line course through the infraorbital canal (P < .001), orbital floor fracture (P < 0.001), and ZMC dislocation or mobility (P = 0.001).

CONCLUSION

Of all ZMC fractures, 37.3% exhibited ION hypoaesthesia. Only ZMC Zingg type B fractures (74.0%) were significantly more associated with ION hypoaesthesia. ION hypoesthesia was more likely (OR = 2.707) when the fracture line course ran through the infraorbital canal, and was less dependent on the degree of displacement. Neuropathic pain symptoms developed after ZMC fractures in 2.2% patients, posing a treatment challenge. Neuropathic pain symptoms were slightly more common among women, and were associated only with type B or C fractures. No other parameters were found to predict the outcome of this post-traumatic neuropathic pain condition.

Neurorrhaphy in Presence of Polyethylene Glycol Enables Immediate Electrophysiological Conduction in Porcine Model of Facial Nerve Injury

Facial nerve trauma often leads to disfiguring facial muscle paralysis. Despite several promising advancements, facial nerve repair procedures often do not lead to complete functional recovery. Development of novel repair strategies requires testing in relevant preclinical models that replicate key clinical features. Several studies have reported that fusogens, such as polyethylene glycol (PEG), can improve functional recovery by enabling immediate reconnection of injured axons; however, these findings have yet to be demonstrated in a large animal model. We first describe a porcine model of facial nerve injury and repair, including the relevant anatomy, surgical approach, and naive nerve morphometry. Next, we report positive findings from a proof-of-concept experiment testing whether a neurorrhaphy performed in conjunction with a PEG solution maintained electrophysiological nerve conduction at an acute time point in a large animal model. The buccal branch of the facial nerve was transected and then immediately repaired by direct anastomosis and PEG application. Immediate electrical conduction was recorded in the PEG-fused nerves (n = 9/9), whereas no signal was obtained in a control cohort lacking calcium chelating agent in one step (n = 0/3) and in the no PEG control group (n = 0/5). Nerve histology revealed putative-fused axons across the repair site, whereas no positive signal was observed in the controls. Rapid electrophysiological recovery following nerve fusion in a highly translatable porcine model of nerve injury supports previous studies suggesting neurorrhaphy supplemented with PEG may be a promising strategy for severe nerve injury. While acute PEG-mediated axon conduction is promising, additional work is necessary to determine if physical axon fusion occurs and the longer-term fate of distal axon segments as related to functional recovery.

LncRNA RMRP knockdown promotes proliferation and migration of Schwann cells by mediating the miR-766-5p/CAND1 axis

The proliferation and migration of Schwann cells (SCs) promote nerve regeneration after facial nerve injury. In recent years, the role of long noncoding RNAs (lncRNAs) in regulating SC proliferation and migration has been gradually uncovered. However, there is little evidence on the function of lncRNA RMRP (lnc-RMRP) in SC growth. In the present study, we performed loss-of-function and overexpression assays to explore the function of lnc-RMRP in SCs. The relationships between lnc-RMRP, miR-766-5p and CAND1 (cullin-associated and neddylation-dissociated 1) were analyzed using bioinformatics analysis, luciferase detection, RNA binding protein immunoprecipitation and RNA pulldown methods. CCK-8, EdU, Transwell and wound healing assays were utilized for the detections of cell proliferation and migration. We found that lnc-RMRP silencing enhanced cell proliferation and migration of SCs, while lnc-RMRP overexpression showed the opposite effect. Mechanistically, lnc-RMRP directly bound to and negatively modulated the expression of miR-766-5p. MiR-766-5p knockdown decreased cell viability, proliferation and migration of SCs, and also reversed the effects of lnc-RMRP silencing. In addition, lnc-RMRP positively regulated CAND1 expression by sponging miR-766-5p. Upregulation of CAND1 rescued the function of lnc-RMRP knockdown in regulating SC proliferation and migration. These data suggested that lnc-RMRP played a significant role in SC proliferation and migration, indicating that lnc-RMRP might be a potential therapeutic target for the treatment of facial nerve injury.

Labelling stem cells with a nanoprobe for evaluating the homing behaviour in facial nerve injury repair

It is crucial and clinically relevant to clarify the homing efficiency and retention of stem cells in different implanting strategies of cell therapy for various injuries. However, the need for a tool for investigating the mechanisms is still unmet. We herein introduce multi-modal BaGdF₅:Yb,Tm nanoparticles as a nanoprobe to label adipose-derived stem cells (ADSCs) and detect the homing behavior with a micro-computed tomography (micro-CT) imaging technique. The migration of cells injected locally or intravenously, with or without a chemokine, CXCL 12, was compared. A higher homing efficiency of ADSCs was observed in both intravenously injected groups, in contrast to the low efficiency of cell retention in local implantation. Meanwhile, CXCL 12 promoted the homing of ADSCs, especially in the intravenous route. Nonetheless, the administration of CXCL 12 showed its therapeutic efficacy, whereas intravenous injection of ADSCs almost did not. Our work provided a tool for in vivo imaging of the behavior of implanted cells in preclinical studies of cell therapy, and more importantly, implied that the parameters for implanting stem cells in clinical operation should be carefully considered.

Effect of proprioceptive neuromuscular facilitation in the treatment of dysfunctions in facial paralysis: a systematic literature review

BACKGROUND

Facial palsy (FP) is defined as an injury of the seventh cranial nerve pair, partial or total, which can be classified as central or peripheral. Proprioceptive neuromuscular facilitation (PNF) is primarily used in the functional recovery of upper and lower limb conditions, however the technique has also been used for FP.

OBJECTIVE

To analyze the effect of PNF in the treatment of dysfunctions in FP.

METHODS

Ten databases including BVS, CENTRAL Cochrane, CINAHL, PEDro, PubMed, Scielo, ScienceDirect, SCOPUS, Web of Science, and Google Scholar were comprehensively searched for dates prior to April 2021. Randomized controlled trials of PNF in individuals with dysfunctions caused by facial paralysis were eligible. Outcomes measures were recovery rate and clinical recovery, both measured by using the House Brackmann Scale. Recovery time was measured in days and synkinesis assessed with the Synkinesis Assessment Questionnaire.

RESULTS

A total of 184 patients were included. In general, the included studies have low methodological quality. None of the five studies used PNF as the sole intervention. In all of the included studies PNF was used in combination with other interventions. Our findings show very low evidence that PNF is more effective than minimal intervention for treating FP.

CONCLUSION

We conclude that given the limited number of studies included and the low methodological quality presented, recommendations based on these studies should be interpreted with caution. The effects of PNF on facial paralysis are not clear.

Deep learning-based facial image analysis in medical research: a systematic review protocol

INTRODUCTION

Deep learning techniques are gaining momentum in medical research. Evidence shows that deep learning has advantages over humans in image identification and classification, such as facial image analysis in detecting people's medical conditions. While positive findings are available, little is known about the state-of-the-art of deep learning-based facial image analysis in the medical context. For the consideration of patients' welfare and the development of the practice, a timely understanding of the challenges and opportunities faced by research on deep-learning-based facial image analysis is needed. To address this gap, we aim to conduct a systematic review to identify the characteristics and effects of deep learning-based facial image analysis in medical research. Insights gained from this systematic review will provide a much-needed understanding of the characteristics, challenges, as well as opportunities in deep learning-based facial image analysis applied in the contexts of disease detection, diagnosis and prognosis.

METHODS

Databases including PubMed, PsycINFO, CINAHL, IEEEXplore and Scopus will be searched for relevant studies published in English in September, 2021. Titles, abstracts and full-text articles will be screened to identify eligible articles. A manual search of the reference lists of the included articles will also be conducted. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses framework was adopted to guide the systematic review process. Two reviewers will independently examine the citations and select studies for inclusion. Discrepancies will be resolved by group discussions till a consensus is reached. Data will be extracted based on the research objective and selection criteria adopted in this study.

ETHICS AND DISSEMINATION

As the study is a protocol for a systematic review, ethical approval is not required. The study findings will be disseminated via peer-reviewed publications and conference presentations.

PROSPERO REGISTRATION NUMBER

CRD42020196473.

Facial nerve regeneration using silicone conduits filled with ammonia-functionalized graphene oxide and frankincense-embedded hydrogel

Background

Silicone tube (ST) conduits have been accepted as a therapeutic alternative to direct nerve suturing in the treatment of nerve injuries; however, the search for optimal adjuncts to maximize the outcomes is still ongoing. Frankincense (Fr) and graphene oxide (GO) have both been cited as neuroregenerative compounds in the literature. This study assesses the efficacy of these materials using a ST conduit in a rat facial nerve motor neuron axotomy model, distal to the stylomastoid foramen.

Methods

Ammonia-functionalized graphene oxide (NH2-GO) and/or Fr extract were embedded in a collagen-chitosan hydrogel and were injected inside a ST. The ST was inserted in the gap between the axotomized nerve stumps. Return of function in eye closure, blinking reflex, and vibrissae movements were assessed and compared to control groups through 30 days following axotomy. To assess the histological properties of regenerated nerves, biopsies were harvested distal to the axotomy site and were visualized through light and fluorescence microscopy using LFB and anti-MBP marker, respectively.

Results

There was no significant difference in behavioral test results between groups. Histological analysis of the nerve sections revealed increased number of regenerating axons and mean axon diameter in NH2-GO group and decreased myelin surface area in Fr group. Using both NH2-GO and Fr resulted in increased number of regenerated axons and myelin thickness compared to the hydrogel group.

Conclusions

The findings suggest a synergistic effect of the substances above in axon regrowth, notably in myelin regeneration, where Fr supposedly decreases myelin synthesis.

The efficacy and safety of cupping therapy for treating of intractable peripheral facial paralysis: A protocol for systematic review and meta-analysis

BACKGROUND

Peripheral facial paralysis (PFP) is a common clinical neurological disease and the incidence of intractable peripheral facial paralysis is on the rise. Symptoms include crooked mouth and eyes, tearing and shallow nasolabial folds. The disease seriously affects the physical and mental health of patients. At present, a large number of clinical studies have shown that cupping is effective in treating intractable peripheral facial paralysis (IPFP). Therefore, the purpose of this review is to evaluate the effectiveness and safety of cupping in the treatment of refractory peripheral facial paralysis.

METHODS

We will conduct a comprehensive and systematic search of relevant documents in the following databases: Medline, PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL), Embase, Chinese Biomedical Literatures Database, China National Knowledge Infrastructure (CNKI), Wang Fang Database, Chinese Scientific Journal Database from inception to February 2021 without any language restriction. The 2 reviewers will be independently completed select research, extract data, evaluate research quality and use the Cochrane risk of bias tool to assess methodological quality. Using revman5.4 software for statistical analysis. The degree of heterogeneity will be Determined through heterogeneity test, to definite whether to adopt a random effects model or a fixed-effects model.

RESULTS

The protocol for the meta-analysis will systematically evaluate the efficacy and safety of cupping therapy for intractable peripheral facial paralysis patients.

CONCLUSION

This study will explore whether or not cupping therapy can be used as one of the non-drug therapies to prevent or treat intractable peripheral facial paralysis.

A meta-analysis uncovers the first sequence variant conferring risk of Bell's palsy

Bell's palsy is the most common cause of unilateral facial paralysis and is defined as an idiopathic and acute inability to control movements of the facial muscles on the affected side. While the pathogenesis remains unknown, previous studies have implicated post-viral inflammation and resulting compression of the facial nerve. Reported heritability estimates of 4-14% suggest a genetic component in the etiology and an autosomal dominant inheritance has been proposed. Here, we report findings from a meta-analysis of genome-wide association studies uncovering the first unequivocal association with Bell's palsy (rs9357446-A; P = 6.79 × 10^-23, OR = 1.23; N_cases = 4714, N_controls = 1,011,520). The variant also confers risk of intervertebral disc disorders (P = 2.99 × 10^-11, OR = 1.04) suggesting a common pathogenesis in part or a true pleiotropy.

Progress in facial reinnervation

Facial nerve injury often results in facial paralysis, which seriously affects the patients both aesthetically and functionally. Facial nerve reinnervation methods, including direct anastomosis, nerve graft, nerve transposition, cross-facial nerve graft, and combined surgeries, have recently become a hot topic with many new procedures being explored. This study summarizes the relevant literatures and discusses the scope of application, advantages, and disadvantages of the different methods. The treatment options or combined surgeries for facial nerve reinnervation should be individualized for specific patients to achieve the best reanimation outcome with good static symmetry, facial tone, and spontaneous, natural, symmetrical, and strong facial movements.

Transcriptome analysis of molecular mechanisms underlying facial nerve injury repair in rats

Although the transcriptional alterations inside the facial nucleus after facial nerve injury have been well studied, the gene expression changes in the facial nerve trunk after injury are still unknown. In this study, we established an adult rat model of facial nerve crush injury by compressing the right lateral extracranial nerve trunk. Transcriptome sequencing, differential gene expression analysis, and cluster analysis of the injured facial nerve trunk were performed, and 39 intersecting genes with significant variance in expression were identified. Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway analyses of the 39 intersecting genes revealed that these genes are mostly involved in leukocyte cell-cell adhesion and phagocytosis and have essential roles in regulating nerve repair. Quantitative real-time polymerase chain reaction assays were used to validate the expression of pivotal genes. Finally, nine pivotal genes that contribute to facial nerve recovery were identified, including Arhgap30, Akr1b8, C5ar1, Csf2ra, Dock2, Hcls1, Inpp5d, Sla, and Spi1. Primary Schwann cells were isolated from the sciatic nerve of neonatal rats. After knocking down Akr1b8 in Schwann cells with an Akr1b8-specific small interfering RNA plasmid, expression levels of monocyte chemoattractant protein-1 and interleukin-6 were decreased, while cell proliferation and migration were not obviously altered. These findings suggest that Akr1b8 likely regulates the interaction between Schwann cells and macrophages through regulation of cytokine expression to promote facial nerve regeneration. This study is the first to reveal a transcriptome change in the facial nerve trunk after facial nerve injury, thereby revealing the potential mechanism underlying repair of facial nerve injury. This study was approved by the Animal Ethics Committee of Nantong University, China in 2018 (approval No. S20180923-007).

Bell’s palsy: clinical and neurophysiologic predictors of recovery

Background

The annual incidence of Bell’s palsy (BP) is 15 to 20 per 100,000 with 40,000 new cases each year, and the lifetime risk is 1 in 60. For decades, clinicians have searched the prognostic tests of sufficient accuracy for acute facial paralysis.

Objective

The present study was designed to verify in BP which clinical or electrophysiological parameters could be considered as predictive of the degree of recovery of normal facial muscle function.

Methods

Sixty-three patients with BP were initially assessed according to the House and Brackmann facial function scoring system “HB system”. All patients were followed for 3 months, the functional recovery then reassessed according to HB system. Nerve conduction studies were measured on the affected side via a bipolar surface stimulator placed over the stylomastoid foramen.

Results

We could not find statistically significant differences between BP with good and poor prognosis as regard age, sex, onset, diabetes, hypertension, dyslipidemia, or the initial HB Score. Compound motor action potential amplitude (CMAP) detected during the initial electroneurography (ENoG) was statistically significant between BP with good and poor prognosis.

Conclusions

The initial ENoG is more predictive of recovery of Bell’s palsy than the initial clinical grading using the HB system. Age, sex, hypertension, diabetes, and dyslipidemia do not seem to correlate with the degree of recovery in Bell’s palsy.

Quantitative analysis of movements in facial nerve palsy with surface electromyography and kinematic analysis

Facial nerve paralysis (FNP) has a significant effect on a person's quality of life. In individuals with FNP undergoing facial rehabilitation, methods to analyze the loss of function are useful in diagnosis, treatment and follow up. To propose a protocol with kinematic analysis coupled with sEMG to evaluate the outcomes of FNP, quantifying the excursion degrees of the facial muscles and symmetry of voluntary movements. 10 patients (Group A) were followed by diagnosis until the end of the rehabilitation program. Kinematic analysis of 20 healthy adults (group B) was performed as a starting point to have a normality range and to test intra-subject and inter- intra rater reliability. An optoelectronic system and sEMG wireless electrodes were used. In Group A, a significant improvement in the movement of frontalis muscle (P = 0.0118) after 4-week treatment from the beginning (T0) 9.8 ± 4.5 mm to the end of rehabilitation (T1) 16.3 ± 5.8 mm and orbicularis oris (P = 0.0143) from T0 14.8 ± 5.5 mm to T1 20.3 ± 3.3 mm and, a reduction of % of maximum voluntary contractions (MVC) at T1 for frontalis and orbicularis compared to T0. This protocol provides meaningful data in a simple, reliable and objective way for the functional assessment of patients with PNF.

Comparative analysis of the nerve transfer methodologies used during surgical treatment of peripheral facial paresis

Introduction. When considering the array of biomedical problems associated with facial nerve palsy (FNP), it is apparent that the problem of choosing an effective type of facial nerve transfer is of paramount relevance. Hence, it is to the pursuit of a solution to the above stated problem that our study is devoted.

Materials and methods. We analyzed the data obtained as a result of assessing the outcome of 149 patients with trauma-caused FNP who had undergone surgical treatments in the period between 2001-2018. The FN nerve transfer techniques utilized were as such: for group 1 – the use as a donor nerve the branch of the accessory nerve innervating the sternocleidomastoid muscle (n=87); group 2 – the descending branch of the hypoglossal and the branch of the accessory nerve (n=62).

Results. In groups 1–2, the FN nerve transfer significantly improved FN function (p <0.01; Wilcoxon Matched Pairs Test), and most patients (n=135; 90.6%) noted an improvement in the clinical status up to degree II-III on the House-Brackmann scale (good result).

Conclusion. The use of the accessory nerve branches to the sternocleidomastoid muscle, as donated, ensures restoration of FN function to levels II-III on the House-Brackmann scale in 89.7% of all operated patients, and the results it achieves do not differ from those of the technically more complex nerve transfer of FN by descending branch of the hypoglossal nerve with combination of branches of the accessory nerve.

Abnormal Emotional Processing and Emotional Experience in Patients with Peripheral Facial Nerve Paralysis: An MEG Study

Abnormal emotional reactions of the brain in patients with facial nerve paralysis have not yet been reported. This study aims to investigate this issue by applying a machine-learning algorithm that discriminates brain emotional activities that belong either to patients with facial nerve paralysis or to healthy controls. Beyond this, we assess an emotion rating task to determine whether there are differences in their experience of emotions. MEG signals of 17 healthy controls and 16 patients with facial nerve paralysis were recorded in response to picture stimuli in three different emotional categories (pleasant, unpleasant, and neutral). The selected machine learning technique in this study was the logistic regression with LASSO regularization. We demonstrated significant classification performances in all three emotional categories. The best classification performance was achieved considering features based on event-related fields in response to the pleasant category, with an accuracy of 0.79 (95% CI (0.70, 0.82)). We also found that patients with facial nerve paralysis rated pleasant stimuli significantly more positively than healthy controls. Our results indicate that the inability to express facial expressions due to peripheral motor paralysis of the face might cause abnormal brain emotional processing and experience of particular emotions.

Give me a kiss! An integrative rehabilitative training program with motor imagery and mirror therapy for recovery of facial palsy

BACKGROUND

Peripheral facial nerve palsy (FNP) can have various causes, such as Bell's palsy or after surgery for acoustic neuroma. Rehabilitation is often required but there is no evidence that any rehabilitation approach is more efficacious than another.

AIM

The purpose of this research was to determine the effects of neurocognitive-rehabilitative approach through mirror-therapy (MT) and motor-imagery (MI), integrated into the traditional rehabilitation with mime-therapy and myofascial-approach.

DESIGN

This study was designed as a double-blind, randomized, controlled trial.

SETTING

This study took place from January 2016 to June 2018 at the Unit of Physical Medicine and Rehabilitation of Umberto I Polyclinic Hospital, Rome, Italy.

POPULATION

Twenty-two patients were randomized into two groups: the mirror therapy group (N.=11, MT and MI) and the traditional rehabilitation group (N.=11, mime-therapy and a myofascial-approach).

METHODS

Outcome assessments were performed before treatment (T0), after one month (T1=10 session, twice/week), after the second and third months (T2=10 twice/week + 5 of MT+MI one/week and T3=10 twice/week + 5 of MT+MI 1/week), and at the 4-week follow-up (T4=2 months follow-up).

RESULTS

The analysis of the functional evaluations show that both groups experienced progressive improvement T0 to T3, with stabilization of the results at the follow-up. There was a significant difference in House-Brackmann-Scale scores between T0 and follow-up in favor of the experimental group. In terms of quality of life (FaCE scale), total scores and social function items improved in both groups from T0 to T3. The experimental group obtained better results with regard to quality of life and emotional depression.

CONCLUSIONS

The integrated use of MT and MI is efficacious in the rehabilitation of FNP, improving facial physical function. Further studies are needed to determine the predictive factors of the recovery of facial mimic.

CLINICAL REHABILITATION IMPACT

The ability of patients with unilateral facial paralysis to recognize and appropriately judge facial expressions and perceive the judgments of others remains underexplored. The likelihood of recovering near-normal facial-function after grade VI facial paralysis is low. Procedures, such as the immediate repair of the facial nerve with an interposed donor graft, might improve facial function in patients with partially injured facial nerves.

Differences in functional brain alterations driven by right or left facial nerve efferent dysfunction: Evidence from early Bell's palsy

BACKGROUND

Bell's palsy is defined as idiopathic unilateral facial nerve palsy. Early Bell's palsy is characterized by emerging asymmetric motor conduction of the facial nerve and obvious imbalance of facial muscle movement, which can result in a substantial psychological impact on patients and trigger brain cortical functional reorganization. However, the differences between the brain functional alterations were driven by right or left facial nerve efferent dysfunction in patients with early Bell's palsy are not fully understood. The neuroimage study in patients with different-sided Bell's palsy in the early stage will help to understand the different mechanisms involved in functional integration driven by unilateral facial efferent nerve dysfunction and to provide the theoretical foundation for the choice of suitable treatment strategy.

METHODS

Sixty-seven patients and 37 age- and sex-matched healthy controls were recruited to undergo resting-state functional magnetic resonance imaging (R-fMRI). Regional brain activity was analyzed by comparing the fractional amplitude of low-frequency fluctuations (fALFF) between right palsy and healthy control, left palsy and healthy control, and right and left palsy groups. The altered brain regions were further selected as seeds in subsequent functional connectivity (FC) analysis, and the correlations between the Toronto Facial Grading System (TFGS) scores and the connectivity alterations were also analyzed.

RESULTS

The right and left Bell's palsy groups showed fALFF alterations compared with the healthy control group, and several brain regions with different fALFF values between the right and left palsy groups were identified. In the right palsy group, overall inter-regional FC increased in the right supramarginal gyrus (SMG), bilateral superior frontal gyrus (SFG), and left precentral gyrus (PreCG), compared with the left palsy group. Furthermore, the brain region pairs with higher FC in the right palsy group were left temporal pole of the superior temporal gyrus (TPOsup) and right SMG, left TPOsup and middle cingulate cortex (MCC), left TPOsup and left PreCG, right SMG and SFG, MCC and left PreCG, left and right SFG, and right SFG and left PreCG. In the right palsy group, the left TPOsup and PreCG showed a negative correlation with the TFGS score, while the right SFG and left PreCG showed a positive correlation with the TFGS scores. In the left palsy group, the left TPOsup and right SMG, and the right SMG and SFG region pairs showed a negative correlation with the TFGS score.

CONCLUSIONS

The fALFF and FC analyses revealed the remodeling of different brain functional networks driven by right or left facial nerve efferent dysfunction in patients with early Bell's palsy. The reintegration mechanisms differed between patients with right and left Bell's palsy. Additionally, the severity of the disease showed different associations with altered FC.

Altered Brain Fraction Amplitude of Low Frequency Fluctuation at Resting State in Patients With Early Left and Right Bell's Palsy: Do They Have Differences?

Purpose: Bell’s palsy refers to acute idiopathic unilateral facial nerve palsy. It is a common disorder of the main motor pathway to the facial muscles. This study aimed to investigate the abnormal fraction amplitude of low frequency fluctuation (fALFF) of the brain in patients with early left and right Bell’s palsy.

Materials and Methods: Sixty-seven patients (left 33, right 34) and 37 age- and sex-matched healthy controls underwent resting-state functional magnetic resonance imaging (R-fMRI) examination. The fALFF values were measured from all subjects and were compared among the left palsy, right palsy, and control groups. Then, correlations between the Toronto Facial Grading System (TFGS) scores of the patients and the fALFF values of abnormal brain regions were analyzed.

Results: Significant group differences in fALFF values among the three groups were observed mainly in the cerebral cortical, subcortical, and deep gray matter regions. Compared with the right Bell’s palsy group, the left Bell’s palsy group showed significantly decreased fALFF values in the left temporal pole of the superior temporal gyrus (TPOsup), right supramarginal, left and right middle cingulate cortex (MCC), left superior frontal gyrus (SFG), and left precentral gyrus (PreCG), and increased fALFF values were observed in the right SFG and PreCG. Furthermore, altered fALFF values correlated positively with the TFGS scores in the left superior TPO, bilateral MCC, and right PreCG, and correlated negatively with the TFGS scores in the right SFG of the left Bell’s palsy group. Altered fALFF values correlated positively with the TFGS scores in the bilateral MCC and right PreCG and correlated negatively with the TFGS scores in the left superior TPO and SFG of the right Bell’s palsy group.

Conclusion: Regulatory mechanisms seem to differ between patients with left and right early Bell’s palsy. The severity of the disease is associated with these functional alterations.

CXCL12 has therapeutic value in facial nerve injury and promotes Schwann cells autophagy and migration via PI3K-AKT-mTOR signal pathway

Facial nerve injury is a clinically common disease accompanied by demyelination of damaged nerves. The remyelination of damaged nerves and the unsatisfactory function recovery are problems that have been plaguing people for a long time. The role that CXCL12 plays after facial nerve injury remains unknown. Our experiments found that the expression of CXCL12 was up-regulated in the early stage of facial nerve injury and decreased after two weeks. Further research found that CXCL12 had no effect on Schwann cells proliferation, apoptosis and cell cycle, while significantly promoted Schwann cells migration. Treatment with CXCL12 decreased the phosphorylation of PI3K, AKT and mTOR, but increased autophagy marker LC3II/I. The CXCL12-induced Schwann cells migration was significantly attenuated by inhibition of autophagy and activation of PI3K pathway through pretreatment with 3-MA and IGF-1 respectively, and this effect was enhanced by PI3K pathway inhibitor LY294002. Animal experiment also confirmed that CXCL12 could improve facial nerve function and myelin regeneration. The findings of this study indicate that CXCL12 can promote the migration of Schwann cells and potentially become a key molecule in the repair of facial nerve injury.

Facial Nerve Paralysis-A Rare Complication of Open Reduction of Zygomaticomaxillary Complex Fractures

Facial nerve paralysis is an unusual formidable complication that can manifest after various maxillofacial surgeries, including open reduction of facial trauma. The branches more predisposed to such injury are the zygomatic and marginal mandibular branches. Zygomaticomaxillary complex (ZMC) fractures are frequently encountered in maxillofacial trauma. The facial nerve has not been described as endangered during ZMC surgery. Paralysis of the buccal branch after ZMC repair with delayed onset has been reported only once. This report describes a patient with immediate facial nerve paralysis after open reduction and internal fixation of an isolated ZMC fracture through an intraoral approach. This is a previously unreported rare complication after ZMC fracture repair that should be discussed as a possibility when obtaining preoperative consent.