The effect of subthreshold continuous electrical stimulation on the facial function of patients with Bell's palsy

Task force of the Brazilian Society of Otology - evaluation and management of peripheral facial palsy

OBJECTIVE

To review key evidence-based recommendations for the diagnosis and treatment of peripheral facial palsy in children and adults.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on peripheral facial palsy were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 main parts: (1) Evaluation and diagnosis of facial palsy: electrophysiologic tests, idiopathic facial palsy, Ramsay Hunt syndrome, traumatic peripheral facial palsy, recurrent peripheral facial palsy, facial nerve tumors, and peripheral facial palsy in children; and (2) Rehabilitation procedures: surgical decompression of the facial nerve, facial nerve grafting, surgical treatment of long-term peripheral facial palsy, and non-surgical rehabilitation of the facial nerve.

CONCLUSIONS

Peripheral facial palsy is a condition of diverse etiology. Treatment should be individualized according to the cause of facial nerve dysfunction, but the literature presents better evidence-based recommendations for systemic corticosteroid therapy.

Application of facial neuromuscular electrical stimulation (fNMES) in psychophysiological research: Practical recommendations based on a systematic review of the literature

Facial neuromuscular electrical stimulation (fNMES), which allows for the non-invasive and physiologically sound activation of facial muscles, has great potential for investigating fundamental questions in psychology and neuroscience, such as the role of proprioceptive facial feedback in emotion induction and emotion recognition, and may serve for clinical applications, such as alleviating symptoms of depression. However, despite illustrious origins in the 19th-century work of Duchenne de Boulogne, the practical application of fNMES remains largely unknown to today's researchers in psychology. In addition, published studies vary dramatically in the stimulation parameters used, such as stimulation frequency, amplitude, duration, and electrode size, and in the way they reported them. Because fNMES parameters impact the comfort and safety of volunteers, as well as its physiological (and psychological) effects, it is of paramount importance to establish recommendations of good practice and to ensure studies can be better compared and integrated. Here, we provide an introduction to fNMES, systematically review the existing literature focusing on the stimulation parameters used, and offer recommendations on how to safely and reliably deliver fNMES and on how to report the fNMES parameters to allow better cross-study comparison. In addition, we provide a free webpage, to easily visualise fNMES parameters and verify their safety based on current density. As an example of a potential application, we focus on the use of fNMES for the investigation of the facial feedback hypothesis.

A Perspective on Electrical Stimulation and Sympathetic Regeneration in Peripheral Nerve Injuries

Peripheral nerve injuries (PNIs) are common and devastating. The current standard of care relies on the slow and inefficient process of nerve regeneration after surgical intervention. Electrical stimulation (ES) has been shown to both experimentally and clinically result in improved regeneration and functional recovery after PNI for motor and sensory neurons; however, its effects on sympathetic regeneration have never been studied. Sympathetic neurons are responsible for a myriad of homeostatic processes that include, but are not limited to, blood pressure, immune response, sweating, and the structural integrity of the neuromuscular junction. Almost one quarter of the axons in the sciatic nerve are from sympathetic neurons, and their importance in bodily homeostasis and the pathogenesis of neuropathic pain should not be underestimated. Therefore, as ES continues to make its way into patient care, it is not only important to understand its impact on all neuron subtypes, but also to ensure that potential adverse effects are minimized. This piece gives an overview of the effects of ES in animals models and in humans while offering a perspective on the potential effects of ES on sympathetic axon regeneration.

Boosting brain-computer interfaces with functional electrical stimulation: potential applications in people with locked-in syndrome

Individuals with a locked-in state live with severe whole-body paralysis that limits their ability to communicate with family and loved ones. Recent advances in brain-computer interface (BCI) technology have presented a potential alternative for these people to communicate by detecting neural activity associated with attempted hand or speech movements and translating the decoded intended movements to a control signal for a computer. A technique that could potentially enrich the communication capacity of BCIs is functional electrical stimulation (FES) of paralyzed limbs and face to restore body and facial movements of paralyzed individuals, allowing to add body language and facial expression to communication BCI utterances. Here, we review the current state of the art of existing BCI and FES work in people with paralysis of body and face and propose that a combined BCI-FES approach, which has already proved successful in several applications in stroke and spinal cord injury, can provide a novel promising mode of communication for locked-in individuals.

Efficacy of adding selective electrical muscle stimulation to usual physical therapy for Bell's palsy: immediate and six-month outcomes

Bell's palsy is the most common cause of facial paralysis, affecting one in every 60 people in their lifetime. Transcutaneously applied selective electrical muscle stimulation could potentially accelerate recovery from Bell's palsy but this intervention remains controversial. Studies have shown benefit, but concerns for lack of efficacy and potential for worsening synkinesis remain. We performed a prospective controlled trial comparing outcomes at initial recovery and six months later with selective electrical muscle stimulation and usual physical therapy versus usual physical therapy alone in adults with acute Bell's palsy. Outcomes were facial function assessed with the House Brackman and eFACE scales. Outcomes were evaluated at discharge and six months after discharge. Discharge occurred when participants were judged to be fully recovered by their treating therapist and supervisor. 38 adults participated in the study. Participants in the electrical stimulation group achieved maximal recovery twice as fast as the control group (2.5 weeks versus 5.2 weeks) with no significant differences in facial function or synkinesis between groups at any time point. This study is the first human trial of electrical stimulation in Bell's palsy to follow patients 6 months from recovery and supports that selective electrical muscle stimulation accelerates recovery and does not increase synkinesis.

Application and underlying mechanism of acupuncture for the nerve repair after peripheral nerve injury: remodeling of nerve system

Peripheral nerve injury (PNI) is a structural event with harmful consequences worldwide. Due to the limited intrinsic regenerative capacity of the peripheral nerve in adults, neural restoration after PNI is difficult. Neurological remodeling has a crucial effect on the repair of the form and function during the regeneration of the peripheral nerve after the peripheral nerve is injured. Several studies have demonstrated that acupuncture is effective for PNI-induced neurologic deficits, and the potential mechanisms responsible for its effects involve the nervous system remodeling in the process of nerve repair. Moreover, acupuncture promotes neural regeneration and axon sprouting by activating related neurotrophins retrograde transport, such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), N-cadherin, and MicroRNAs. Peripheral nerve injury enhances the perceptual response of the central nervous system to pain, causing central sensitization and accelerating neuronal cell apoptosis. Together with this, the remodeling of synaptic transmission function would worsen pain discomfort. Neuroimaging studies have shown remodeling changes in both gray and white matter after peripheral nerve injury. Acupuncture not only reverses the poor remodeling of the nervous system but also stimulates the release of neurotrophic substances such as nerve growth factors in the nervous system to ameliorate pain and promote the regeneration and repair of nerve fibers. In conclusion, the neurological remodeling at the peripheral and central levels in the process of acupuncture treatment accelerates nerve regeneration and repair. These findings provide novel insights enabling the clinical application of acupuncture in the treatment of PNI.

Effects of Electrical Stimulation on Facial Paralysis Recovery after Facial Nerve Injury: A Review on Preclinical and Clinical Studies

Various methods have been used to improve function and manage facial nerve injury. Although electrical stimulation therapy is frequently used to treat facial paralysis, its effects have been found to vary and no clear standards have been developed. The current review describes the results of preclinical and clinical studies evaluating the effectiveness of electrical stimulation therapy in promoting the recovery of a peripheral facial nerve injury. Evidence is presented showing the efficacy of electrical stimulation in promoting nerve regeneration after peripheral nerve injuries in both animal models and human patients. The ability of electrical stimulation to promote the recovery of facial paralysis was found to depend on the type of injury (compression or transection), the species of animal tested, the type of disease, the frequency and method of electrical stimulation, and the duration of the follow-up. Electrical stimulation, however, can also have potential negative outcomes, such as reinforcing synkinesis, including mistargeted axonal regrowth via inappropriate routes; excessive collateral axonal branching at the lesion site; and multiple innervations at neuromuscular junctions. Because of the inconsistencies among studies and the low quality of evidence, electrical stimulation therapy is not currently regarded as a primary treatment of facial paralysis in patients. However, understanding the effects of electrical stimulation, as determined in preclinical and clinical studies, is important for the potential validity of future research on electrical stimulation.

Intraoperative electrical stimulation for persistent, post-traumatic facial paralysis

Approximately 7-10% of temporal bone fractures result in facial nerve paralysis. Treatment is dependent upon the severity of the nerve trauma and can range from conservative medical management to surgical intervention. A study by Hato et al. detailed the relationship between surgical timing and recovery rate for patients with facial nerve palsy secondary to temporal bone trauma. The rates of complete recovery and good recovery decline that the longer surgical intervention is delayed. We present the case of a 14-year-old male with a temporal bone fracture and delayed onset right-sided facial paralysis. This patient was treated with a transmastoid middle cranial fossa (MCF) approach with intraoperative electrical stimulation of the perigeniculate portion of the facial nerve. Despite a 53-day delay between trauma and surgical intervention, the patient's facial function improved from House Brackmann (HB) grade VI to grade II within 6 months. Intraoperative facial nerve stimulation, which we have previously used for unresolved Bell's palsy, may be useful for patients with post-traumatic, persistent facial paralysis.

Pathogenesis, diagnosis and therapy of facial synkinesis: A systematic review and clinical practice recommendations by the international head and neck scientific group

Introduction

Post-paralytic facial synkinesis after facial nerve injury produces functional disabilities and mimetic deficits, but also cosmetic and non-motor psychosocial impairments for the patients. These patients typically have a high and continuous high motivation for rehabilitation. The aim is to inform the affected patients and their therapeutic professionals (otorhinolaryngologist - head and neck surgeons; oral-maxillofacial surgeons, plastic and reconstructive surgeons, neurosurgeons, neurologists, and mime therapists be it speech and language therapy- or physiotherapy-based) and to provide practical recommendations for diagnostics and a stepwise systematic treatment approach of facial synkinesis.

Methods

In the first phase, a systematic literature search on the topic in PubMed and ScienceDirect starting in 2008 resulted in 132 articles. These were the basis for the review and a comprehensive series of consensus statements on the most important diagnostic tests and treatment options. In the second phase, one consensus article circulated among the membership of the International Head and Neck Scientific Group until a final agreement was reached for all recommendations.

Results

Diagnostics should include a standardized assessment of the degree of synkinesis using validated clinician-graded instruments and synkinesis-specific patient-reported outcome measures. Treatments for facial synkinesis include facial training mainly based on facial biofeedback retraining, chemodenervation with botulinum toxin, selective neurectomy, myectomy, and any combination treatment of these options.

Conclusion

A basic understanding of the pathomechanisms of synkinesis is essential to understand the treatment strategies. A standardized assessment of the synkinetic symptoms and the individual synkinesis pattern is needed. The first-line treatment is facial training, followed by botulinum toxin. Surgery is reserved for individual cases with unsatisfactory first-line treatment.

Physical therapy for facial nerve paralysis (Bell's palsy): An updated and extended systematic review of the evidence for facial exercise therapy

OBJECTIVE

To conduct a systematic review of the effectiveness of facial exercise therapy for facial palsy patients, updating an earlier broader Cochrane review; and to provide evidence to inform the development of telerehabilitation for these patients.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, Cochrane Library, PEDro and AMED for relevant studies published between 01 January 2011 and 30 September 2020.

METHODS

Predetermined inclusion/exclusion criteria were utilised to shortlist abstracts. Two reviewers independently appraised articles, systematically extracted data and assessed the quality of individual studies and reviews (using GRADE and AMSTAR-2, respectively). Thematic analysis used for evidence synthesis; no quantitative meta-analysis conducted. The review was registered with PROSPERO (CRD42017073067).

RESULTS

Seven new randomised controlled trials, nine observational studies, and three quasi-experimental or pilot studies were identified (n  =  854 participants). 75% utilised validated measures to record changes in facial function and/or patient-rated outcomes. High-quality trials (4/7) all reported positive impacts; as did observational studies rated as high/moderate quality (3/9). The benefit of therapy at different time points post-onset and for cases of varying clinical severity is discussed. Differences in study design prevented data pooling to strengthen estimates of therapy effects. Six new review articles identified were all rated critically low quality.

CONCLUSION

The findings of this targeted review reinforce those of the earlier more general Cochrane review. New research studies strengthen previous conclusions about the benefits of facial exercise therapy early in recovery and add to evidence of the value in chronic cases. Further standardisation of study design/outcome measures and evaluation of cost-effectiveness are recommended.

Selective Neural Electrical Stimulation of an Injured Facial Nerve Using Chronically Implanted Dual Cuff Electrodes

Facial nerve (FN) injury can lead to debilitating and permanent facial paresis/paralysis (FP), where facial muscles progressively lose tone, atrophy, and ultimately reduce to scar tissue. Despite considerable efforts in the recent decades, therapies for FP still possess high failure rates and provide inadequate recovery of muscle function. In this pilot study, we used a feline model to demonstrate the potential for chronically implanted multichannel dual-cuff electrodes (MCE) to selectively stimulate injured facial nerves at low current intensities to avoid stimulus-induced neural injury. Selective facial muscle activation was achieved over six months after FN injury and MCE implantation in two domestic shorthaired cats (Felis catus). Through utilization of bipolar stimulation, specific muscles were activated at significantly lower electrical currents than was achievable with single channel stimulation. Moreover, interval increases in subthreshold current intensities using bipolar stimulation enabled a graded EMG voltage response while maintaining muscle selectivity. Histological examination of neural tissue at implant sites showed no appreciable signs of stimulation-induced nerve injury. Thus, by selectively activating facial musculature six months following initial FN injury and MCE implantation, we demonstrated the potential for our neural stimulator system to be safely and effectively applied to the chronic setting, with implications for FP treatment.

Acute Peripheral Facial Nerve Palsy in Children and Adolescents: Clinical Aspects and Treatment Modalities

BACKGROUND

Peripheral facial nerve palsy is a relatively frequent, rather idiopathic, and isolated nonprogressive disorder with a tendency toward spontaneous recovery in children. It is primarily characterized by unilateral paresis or paralysis of the mimic musculature affecting verbal communication, social interactions, and quality of life.

OBJECTIVE

This study aimed to evaluate the clinical aspects and efficacy of different therapeutic modalities in the population of children and adolescents with acute peripheral facial nerve palsy, the quality and recovery rate in comparison to different therapy modalities and etiological factors as well as to determine parameters of recovery according to the age of patients.

METHODS

The retrospective study included children and adolescents (n=129) with an acute onset of peripheral facial nerve palsy, diagnosed and treated in the Clinic of Neurology and Psychiatry for Children and Youth in Belgrade (2000-2018). The mean age of the patients was 11.53 years (SD±4.41). Gender distribution: 56.6% female and 43.4% male patients.

RESULTS

There were 118 (91.5%) patients with partial and 11 (8.5%) patients with complete paralysis. Left-sided palsy occurred in 67 (51.9%) patients, right-sided in 58 (45.0%), while there were 4 (3.1%) bilateral paralyses. The most common etiological factor was idiopathic (Bell's palsy) - 74 (57.4%) patients followed by middle ear infections - 16 (12.4%). Regardless of etiology, age, and therapy protocols, there was a significant recovery in most of the patients (p<0.001), without significant differences in recovery rate. Comparison of inpatient and outpatient populations showed significant differences regarding the number of relapses, severity of clinical presentation, and recovery rate in relation to etiology.

CONCLUSION

Bell's palsy is shown to be the most common cause of peripheral facial nerve palsy in children and adolescents, regardless of gender. It is followed by mid-ear infections, respiratory infections, and exposure to cold. Most children and adolescents recovered in three weeks after initial presentation, regardless of etiology, age, and therapy.

Is There a Difference in Facial Emotion Recognition after Stroke with vs. without Central Facial Paresis?

The Facial Feedback Hypothesis (FFH) states that facial emotion recognition is based on the imitation of facial emotional expressions and the processing of physiological feedback. In the light of limited and contradictory evidence, this hypothesis is still being debated. Therefore, in the present study, emotion recognition was tested in patients with central facial paresis after stroke. Performance in facial vs. auditory emotion recognition was assessed in patients with vs. without facial paresis. The accuracy of objective facial emotion recognition was significantly lower in patients with vs. without facial paresis and also in comparison to healthy controls. Moreover, for patients with facial paresis, the accuracy measure for facial emotion recognition was significantly worse than that for auditory emotion recognition. Finally, in patients with facial paresis, the subjective judgements of their own facial emotion recognition abilities differed strongly from their objective performances. This pattern of results demonstrates a specific deficit in facial emotion recognition in central facial paresis and thus provides support for the FFH and points out certain effects of stroke.

Selective Electrical Surface Stimulation to Support Functional Recovery in the Early Phase After Unilateral Acute Facial Nerve or Vocal Fold Paralysis

This article addresses the potential clinical value of surface electrical stimulation in the acute phase of denervation after the onset of facial nerve or recurrent laryngeal nerve paralysis. These two nerve lesions are the most frequent head and neck nerve lesions. In this review, we will work out several similarities concerning the pathophysiology features and the clinical scenario between both nerve lesions, which allow to develop some general rules for surface electrical stimulation applicable for both nerve lesions. The focus is on electrical stimulation in the phase between denervation and reinnervation of the target muscles. The aim of electrostimulation in this phase of denervation is to bridge the time until reinnervation is complete and to maintain facial or laryngeal function. In this phase, electrostimulation has to stimulate directly the denervated muscles, i.e. muscle stimulation and not nerve stimulation. There is preliminary data that early electrostimulation might also improve the functional outcome. Because there are still caveats against the use of electrostimulation, the neurophysiology of denervated facial and laryngeal muscles in comparison to innervated muscles is explained in detail. This is necessary to understand why the negative results published in several studies that used stimulation parameters are not suitable for denervated muscle fibers. Juxtaposed are studies using parameters adapted for the stimulation of denervated facial or laryngeal muscles. These studies used standardized outcome measure and show that an effective and tolerable electrostimulation of facial and laryngeal muscles without side effects in the early phase after onset of the lesions is feasible, does not hinder nerve regeneration and might even be able to improve the functional outcome. This has now to be proven in larger controlled trials. In our view, surface electrical stimulation has an unexploited potential to enrich the early therapy concepts for patients with unilateral facial or vocal fold paralysis.

Efficacy of electrotherapy in Bell's palsy treatment: A systematic review

BACKGROUND

Up to now there is not enough evidence that supports the use of electrotherapy in the treatment of Bell's palsy.

OBJECTIVE

Through a systematic review, we aimed to verify whether the use of electrotherapy is effective for treating Bell's palsy or peripheral paralysis.

METHODS

Publications were searched in PubMed, EBSCO and Web of Science. The present systematic review included studies that analyzed the electrotherapy as a therapeutic method for treating individuals with Bell's palsy, in order to recover the function of facial muscles.

RESULTS

Seven studies involving a total of 131 cases and 113 controls were included in this systematic review. In the studies analyzed, patients received electrotherapy combined with other treatments such as hot-wet facial napkins, massages and muscle reeducation. Although the effect of electrotherapy alone was not evaluated, the use of electrotherapy combined with other treatments produced a significant improvement in the individuals evaluated.

CONCLUSIONS

Due to the diverse methodologies used and the small number of individuals included in the studies, we could not fully prove the efficacy of electrotherapy for treating Bell's Palsy. Future studies with larger samples and homogenous populations should be performed to obtain conclusive results.

The Efficacy of Low-Level Laser Therapy in the Treatment of Bell's Palsy in Diabetic Patients

Introduction: The most common causes of the abrupt onset of unilateral facial weakness are stroke and Bell's palsy. The drug regimen together with electrical stimulation was more effective in treating Bell's palsy than conventional drug treatment alone. We aimed to evaluate more effective and safe therapies for the treatment of Bell's palsy. Methods: This clinical interventional study was conducted on 30 diabetic patients with Bell's palsy who referred to a pain clinic for 1 year and were treated by low-level laser (LLL). The system of House-Brackmann was used for assessing the severity of nerve damage and patients were evaluated by electromyography and nerve conduction study (NCS) before and after treatment with low-level laser. These patients had not consumed any other medication for facial nerve palsy. Results: In the present study, 30 cases with poorly controlled diabetes mellitus (18 females and 12 males) were studied. After 12 sessions of low-level laser therapy (LLLT), we could observe complete recovery in 18 patients and partial recovery in 6 patients after 3 months. Conclusion: The recovery rate showed that LLLT is a safe, reliable and proper alternative approach for the treatment of facial nerve palsy, especially in the presence of underlying conditions such as diabetes mellitus.

Protocol for randomized controlled trial of electric stimulation with high-volt twin peak versus placebo for facial functional recovery from acute Bell's palsy in patients with poor prognostic factors

BACKGROUND

Electric stimulation (ES) can prevent muscle atrophy and promote tissue healing and therefore may help prevent sequelae of Bell's palsy but due to lack of high-quality studies, the effectiveness of ES in Bell's palsy remains controversial. Here we describe a protocol to evaluate the effects of monophasic high volt ES in patients with Bell's palsy and poor prognosis for recovery.

RESULTS

This is a protocol for a prospective, double-blinded, randomized, placebo-controlled study. Participants include adults with acute Bell's palsy with poor prognosis for full recovery due to complete paralysis or being over age 60. ES will be a monophasic, high-volt pulsed waveform, 100μsec pulse duration, 35 hertz, motor-level intensity. Follow up will be at months 1, 2, 3 and 6. The primary outcome will be the proportion of patients with complete recovery using the eFACES tool. Secondary outcomes include patient reported quality of life measured by FaCE and the synkinesis assessment questionnaires, objective photographs, time to complete recovery, adverse effects, and tolerability.

CONCLUSION

This protocol has the potential to provide high quality evidence regarding the effects, up to 6 months after onset, of pulsed monophasic high-volt ES for patients with acute Bell's palsy and poor prognosis for complete recovery.

Advances in electrical and magnetic stimulation on nerve regeneration

Central and peripheral nerve injuries pose a great threat to people. Complications such as inflammation, muscle atrophy, traumatic neuromas and delayed reinnervation can bring huge challenges to clinical practices and barriers to complete nerve regrowth. Physical interventions such as electrical and magnetic stimulation show satisfactory results with varying parameters for acute and chronic nerve damages. The biological basis of electrical and magnetic stimulation mainly relies on protein synthesis, ion channel regulation and growth factor secretion. This review focuses on the various paradigms used in different models of electrical and magnetic stimulation and their regenerative potentials and underlying mechanisms in nerve injuries. The combination of physical stimulation and conductive biomaterial scaffolds displays an infinite potentiality in translational application in nerve regeneration.

Altered facial muscle innervation pattern in patients with postparetic facial synkinesis

OBJECTIVES/HYPOTHESIS

Using surface electrostimulation, we aimed to use facial nerve mapping (FNM) in healthy subjects and patients with postparetic facial synkinesis (PPFS) to define functional facial target regions that can be stimulated selectively.

STUDY DESIGN

Single-center prospective cohort study.

METHODS

FNM was performed bilaterally in 20 healthy subjects and 20 patients with PPFS. Single-pulse surface FNM started at the main trunk of the facial nerve and followed the peripheral branches in a distal direction. Stimulation started with 0.1 mA and increased in 0.1 mA increments. The procedure was simultaneously video recorded and evaluated offline.

RESULTS

A total of 1,873 spots were stimulated, and 1,875 facial movements were evaluated. The stimulation threshold was higher on the PPFS side (average = 9.8 ± 1.0 mA) compared to the contralateral side (4.1 ± 0.8 mA) for all stimulation sites or compared to healthy subjects (4.1 ± 0.5 mA; all P < .01). In healthy subjects, selective electrostimulation ± one unintended coactivation was possible at all sites in >80% of cases, with the exception of pulling up the corner of the mouth (65%-75%). On the PPFS side, stimulation was possible for puckering lips movements in 60%/75% (selective stimulation ± one coactivation, respectively), blinking in 55%/80%, pulling up the corner of the mouth in 50%/85%, brow raising in 5%/85, and raising the chin in 0%/35% of patients, respectively.

CONCLUSIONS

FNM mapping for surgical planning and selective electrostimulation of functional facial regions is possible even in patients with PPFS. FNM may be a tool for patient-specific evaluation and placement of electrodes to stimulate the correct nerve branches in future bionic devices (e.g., for a bionic eye blink).

LEVEL OF EVIDENCE

2b Laryngoscope, 130:E320-E326, 2020.

Electroacupuncture promotes peripheral nerve regeneration after facial nerve crush injury and upregulates the expression of glial cell-derived neurotrophic factor

The efficacy of electroacupuncture in the treatment of peripheral facial paralysis is known, but the specific mechanism has not been clarified. Glial cell-derived neurotrophic factor (GDNF) has been shown to protect neurons by binding to N-cadherin. Our previous results have shown that electroacupuncture could increase the expression of N-cadherin mRNA in facial neurons and promote facial nerve regeneration. In this study, the potential mechanisms by which electroacupuncture promotes nerve regeneration were elucidated through assessing the effects of electroacupuncture on GDNF and N-cadherin expression in facial motoneurons of rabbits with peripheral facial nerve crush injury. New Zealand rabbits were randomly divided into a normal group (normal control, n = 21), injury group (n = 45) and electroacupuncture group (n = 45). Model rabbits underwent facial nerve crush injury only. Rabbits in the electroacupuncture group received facial nerve injury, and then underwent electroacupuncture at Yifeng (TE17), Jiache (ST6), Sibai (ST2), Dicang (ST4), Yangbai (GB14), Quanliao (SI18), and Hegu (LI4; only acupuncture, no electrical stimulation). The results showed that in behavioral assessments, the total scores of blink reflex, vibrissae movement, and position of apex nasi, were markedly lower in the EA group than those in the injury group. Hematoxylin-eosin staining of the right buccinator muscle of each group showed that the cross-sectional area of buccinator was larger in the electroacupuncture group than in the injury group on days 1, 14 and 21 post-surgery. Toluidine blue staining of the right facial nerve tissue of each group revealed that on day 14 post-surgery, there was less axonal demyelination and fewer inflammatory cells in the electroacupuncture group compared with the injury group. Quantitative real time-polymerase chain reaction showed that compared with the injury group, N-cadherin mRNA levels on days 4, 7, 14 and 21 and GDNF mRNA levels on days 4, 7 and 14 were significantly higher in the electroacupuncture group. Western blot assay displayed that compared with the injury group, the expression of GDNF protein levels on days 7, 14 and 21 were significantly upregulated in the electroacupuncture group. The histology with hematoxylin-eosin staining and Nissl staining of brainstem tissues containing facial neurons in the middle and lower part of the pons exhibited that on day 7 post-surgery, there were significantly fewer apoptotic neurons in the electroacupuncture group than in the injury group. By day 21, there was no significantly difference in the number of neurons between the electroacupuncture and normal groups. Taken together, these results have confirmed that electroacupuncture promotes regeneration of peripheral facial nerve injury in rabbits, inhibits neuronal apoptosis, and reduces peripheral inflammatory response, resulting in the recovery of facial muscle function. This is achieved by up-regulating the expression of GDNF and N-cadherin in central facial neurons.

Electrical stimulation promotes regeneration and re-myelination of axons of injured facial nerve in rats

Objective To investigate the effects of electrical stimulation (ES) on the nerve regeneration and functional recovery of facial expression muscles in facial nerve defect rats. Methods Sixty rats were surgically introduced with a 1-cm defect on the right facial nerves and evenly divided into the Surgery group (Group A, the main trunk of the right facial nerve was surgically cut-off with a 1.0 cm at the foramina stylomastoideum) and the Surgery + ES group (Group B). Twenty normal rats were as normal control group (without receiving surgery or ES). For rats in group B, the orbicularis oris muscle of the right paralyzed face was stimulated with an electrical pulse of 3 V, 20 Hz and 0.3 mA for 1 h each day. The effects of ES on the facial muscle movement, compound muscle action potentials (CMAPs), histological structure, and the expression levels of S100B and NF200 proteins were comparatively studied. Results In group A, facial paralysis scores were slightly improved from day 1 to 28; the facial nerve trunks had swelled and malformed till day 14; and CMAPs could be induced in fewer animals and were abnormal, resulting in a slow recovery of the facial muscle movement. In group B, facial paralysis scores were improved from 4 to 2.6 during the 4 weeks; more rats showed a higher amplitude and shorter latency of CMAPs from day 14 to 28 after surgery; and increased axons and the expression of S100B and NF200 proteins and gradually decreased swelling in the injured facial nerve. Conclusion ES promotes outgrowth and myelination of axons and a partial functional recovery of facial muscles in injured facial nerve rats.

Cutaneous Sensibility Changes in Bell's Palsy Patients

Objective Bell's palsy is a cranial nerve VII dysfunction that renders the patient unable to control facial muscles from the affected side. Nevertheless, some patients have reported cutaneous changes in the paretic area. Therefore, cutaneous sensibility changes might be possible additional symptoms within the clinical presentation of this disorder. Accordingly, the aim of this research was to investigate the relationship between cutaneous sensibility and facial paralysis severity in these patients. Study Design Prospective longitudinal cohort study. Settings Tertiary care medical center. Subjects and Methods Twelve acute-onset Bell's palsy patients were enrolled from March to September 2009. In addition, 12 sex- and age-matched healthy volunteers were tested. Cutaneous sensibility was evaluated with pressure threshold and 2-point discrimination at 6 areas of the face. Facial paralysis severity was evaluated with the House-Brackmann scale. Results Statistically significant correlations based on the Spearman's test were found between facial paralysis severity and cutaneous sensitivity on forehead, eyelid, cheek, nose, and lip ( P < .05). Additionally, significant differences based on the Student's t test were observed between both sides of the face in 2-point discrimination on eyelid, cheek, and lip ( P < .05) in Bell's palsy patients but not in healthy subjects. Conclusion Such results suggest a possible relationship between the loss of motor control of the face and changes in facial sensory information processing. Such findings are worth further research about the neurophysiologic changes associated with the cutaneous sensibility disturbances of these patients.

Approaches to Peripheral Nerve Repair: Generations of Biomaterial Conduits Yielding to Replacing Autologous Nerve Grafts in Craniomaxillofacial Surgery

Peripheral nerve injury is a common clinical entity, which may arise due to traumatic, tumorous, or even iatrogenic injury in craniomaxillofacial surgery. Despite advances in biomaterials and techniques over the past several decades, reconstruction of nerve gaps remains a challenge. Autografts are the gold standard for nerve reconstruction. Using autografts, there is donor site morbidity, subsequent sensory deficit, and potential for neuroma development and infection. Moreover, the need for a second surgical site and limited availability of donor nerves remain a challenge. Thus, increasing efforts have been directed to develop artificial nerve guidance conduits (ANCs) as new methods to replace autografts in the future. Various synthetic conduit materials have been tested in vitro and in vivo, and several first- and second-generation conduits are FDA approved and available for purchase, while third-generation conduits still remain in experimental stages. This paper reviews the current treatment options, summarizes the published literature, and assesses future prospects for the repair of peripheral nerve injury in craniomaxillofacial surgery with a particular focus on facial nerve regeneration.

Prevalence of Bell's palsy in Qena Governorate, Egypt

BACKGROUND AND PURPOSE

There have been few studies to estimate the prevalence of Bell's palsy (BP) in Arab countries. A community-based study was conducted to estimate the prevalence, incidence rates, precipitating factors, and outcome of BP in Qena Governorate, Egypt.

SUBJECTS AND METHODS

A door-to-door survey was carried out, with random sampling of 10 districts, involving 9303 inhabitants, 51.1% males and 48.9% females. Seventeen subjects were positive in screening questionnaire and referred to Qena University hospital and were subjected to a full clinical examination, House Brackmann's Facial grading system.

RESULTS

In a total population of 9303 individuals, 15 cases were confirmed as having BP giving a prevalence rate (PR) 161/10(5) for all ages 95%CI (80-243). It was slightly but not significantly higher among women and the rural community. The incidence rate of BP was 107/10(5). The highest age-specific rate was 40-49 years age. The most frequent precipitating factors for an episode of BP were exposure to air draft in 40%, physical stress (13.3%), and upper respiratory tract infection (13.3%). Moreover, 46.7% had predisposing risk factors, DM and hypertension in 33.3%. Sixty percent of cases had complication and poor outcome.

CONCLUSION

The overall prevalence and incidence rates of BP in Qena governorate were high. This could be related to the variation in day and night temperature in our community and the susceptibility to air draft exposure during the night. The high frequency of poor outcome among studied cases suggests that better local guidelines should be implemented to recognize and treat BP.