[Salivary Gland Tumors: Limitations of International Guidelines and Status of the planned AWMF-S3-Guideline]. / Speicheldrüsentumoren: Limitationen der internationalen Guidelines und Bearbeitungsstand der AWMF-S3-Leitlinie.

Primary salivary gland carcinomas are not among the common head and neck tumors. They are characterized by manifold different histological types. Clinically, malignant tumors often cannot be distinguished from benign tumors, so that in these cases malignancy is only established by histopathological diagnosis. These are all reasons why there are relatively few clinical trials on the diagnosis, therapy and follow-up of these tumors. This in turn has the consequence that often only recommendations with limited evidence can be made in clinical guidelines. The most important international guidelines are the National Comprehensive Cancer Network (NCCN) guideline of 2023, the American Society of Clinical Oncology (ASCO) guideline of 2021, the European Society for Medical Oncology (ESMO) guideline of 2022 and still the British National Multidisciplinary guideline of 2016. These 4 international guidelines with their strengths and limitations are presented and commented here. Against this background, the development of a first German S3 clinical guideline on salivary gland tumors is important and expected to be completed in 2023. For the first time in the German guideline program on oncology, benign and malignant tumors are presented together in order to comprehensively do justice to the special features of salivary gland tumors.

[Tinnitus]. / Tinnitus.

Tinnitus is a highly prevalent symptom and a common reason for seeing an otolaryngologist. Since tinnitus can go hand in hand with hearing loss, the step-by-step clarification of hearing loss is one of the essential ENT examinations for tinnitus sufferers. The anamnesis and medical history are relevant, since a multidimensional interaction with the tinnitus can be important for the treatment, especially in the case of a psychological comorbidity. In the vast majority of patients, no causal factor can be found. In the absence of external stimuli, phantom perceptions of tones or noises are held responsible for subjective tinnitus, which probably arises from pathological changes of the auditory pathway, but also in non-auditory cortical structures. In the case of acute tinnitus, a comprehensive audiological assessment is needed, and if the hearing threshold is normal, counseling is the priority. The patient must be informed about the nature of these benign symptoms. So far, there is no acute therapy that has been proven to increase the probability of healing, i.e. the disappearance of the acute tinnitus. Only if the hearing threshold descended, for instance in case of sudden idiopathic hearing loss, therapy of the underlying disease can also lead to improvement or healing of the acute tinnitus. Counseling for chronic tinnitus with high burden is also about reducing exaggerated expectations of healing that cannot be fulfilled. The training of habituation strategies is important. The standard of therapy for chronic tinnitus with psychological strain represents cognitive behavioral therapy for dealing with the tinnitus in a beneficial way. Tinnitus is a symptom of a very heterogeneous group of patients. In the future, it is to be hoped that digital applications and interventions in particular will be evaluated in quality-controlled clinical studies in order to be able to further personalize patient therapy.

Management of Recurrent Well-Differentiated Thyroid Carcinoma in the Neck: A Comprehensive Review.

Surgery has been historically the preferred primary treatment for patients with well-differentiated thyroid carcinoma and for selected locoregional recurrences. Adjuvant therapy with radioactive iodine is typically recommended for patients with an intermediate to high risk of recurrence. Despite these treatments, locally advanced disease and locoregional relapses are not infrequent. These patients have a prolonged overall survival that may result in long periods of active disease and the possibility of requiring subsequent treatments. Recently, many new options have emerged as salvage therapies. This review offers a comprehensive discussion and considerations regarding surgery, active surveillance, radioactive iodine therapy, ultrasonography-guided percutaneous ablation, external beam radiotherapy, and systemic therapy for well-differentiated thyroid cancer based on relevant publications and current reference guidelines. We feel that the surgical member of the thyroid cancer management team is empowered by being aware and facile with all management options.

Machine-Learning-Based Detecting of Eyelid Closure and Smiling Using Surface Electromyography of Auricular Muscles in Patients with Postparalytic Facial Synkinesis: A Feasibility Study.

Surface electromyography (EMG) allows reliable detection of muscle activity in all nine intrinsic and extrinsic ear muscles during facial muscle movements. The ear muscles are affected by synkinetic EMG activity in patients with postparalytic facial synkinesis (PFS). The aim of the present work was to establish a machine-learning-based algorithm to detect eyelid closure and smiling in patients with PFS by recording sEMG using surface electromyography of the auricular muscles. Sixteen patients (10 female, 6 male) with PFS were included. EMG acquisition of the anterior auricular muscle, superior auricular muscle, posterior auricular muscle, tragicus muscle, orbicularis oculi muscle, and orbicularis oris muscle was performed on both sides of the face during standardized eye closure and smiling tasks. Machine-learning EMG classification with a support vector machine allowed for the reliable detection of eye closure or smiling from the ear muscle recordings with clear distinction to other mimic expressions. These results show that the EMG of the auricular muscles in patients with PFS may contain enough information to detect facial expressions to trigger a future implant in a closed-loop system for electrostimulation to improve insufficient eye closure and smiling in patients with PFS.

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.

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.

Selective Surface Electrostimulation of the Denervated Zygomaticus Muscle.

This article describes a first attempt to generate a standardized and safe selective surface electrostimulation (SES) protocol, including detailed instructions on electrode placement and stimulation parameter choice to obtain a selective stimulation of the denervated zygomaticus muscle (ZYG), without unwanted simultaneous activation of other ipsilateral or contralateral facial muscles. METHODS: Single pulse stimulation with biphasic triangular and rectangular waveforms and pulse widths (PW) of 1000, 500, 250, 100, 50, 25, 15, 10, 5, 2, 1 ms, at increasing amplitudes between 0.1 and 20 mA was performed. Stimulations delivered in trains were assessed at a PW of 50 ms only. The stimulation was considered successful exclusively if it drew the ipsilateral corner of the mouth upwards and outwards, without the simultaneous activation of other ipsilateral or contralateral facial muscles. I/t curves, accommodation quotient, rheobase, and chronaxie were regularly assessed over 1-year follow-up. RESULTS: 5 facial paralysis patients were assessed. Selective ZYG response in absence of discomfort and unselective contraction of other facial muscle was reproducibly obtained for all the assessed patients. The most effective results with single pulses were observed with PW ≥ 50 ms. The required amplitude was remarkably lower (≤5 mA vs. up to 15 mA) in freshly diagnosed (≤3 months) than in long-term facial paralysis patients (>5 years). Triangular was more effective than rectangular waveform, mostly because of the lower discomfort threshold of the latter. Delivery of trains of stimulation showed similar results to the single pulse setting, though lower amplitudes were necessary to achieve the selective ZYG response. Initial reinnervation signs could be detected effectively by needle-electromyography (n-EMG). CONCLUSION: It is possible to define stimulation parameters able to elicit an effective selective stimulation of a specific facial muscle, in our case, of the ZYG, without causing discomfort to the patient and without causing unwanted unspecific reactions of other ipsilateral and/or contralateral facial muscles. We observed that the SES success is strongly conditioned by the correct electrode placement, which ideally should exclusively interest the area of the target muscles and its immediate proximity.

Laryngeal Electromyography.

Laryngeal electromyography (LEMG) is an important diagnostic and prognostic tool in neurolaryngology. This chapter presents the advances in LEMG in the last 5 years based on clinical trials. LEMG is in most cases an office-based procedure for decision making in neurolaryngology. When performed in a standardized way, LEMG helps to differentiate abnormal function of the vocal folds from nonorganic disorders. It is mainly used to confirm the diagnosis of vocal fold paralysis (VFP) and is less frequently used for the diagnosis of myopathies and motor neuron disorders. Also, the value of LEMG for other diseases than VFP is presented. First consensus recommendations for standard performance of LEMG have been published. This will facilitate the comparison of results from different researchers in the future. For many years, LEMG focused on the thyroarytenoid muscle. Data are presented showing that now more and more studies are performed including other laryngeal muscles, most importantly the posterior cricoarytenoid muscle and cricothyroid muscle. Diagnostics and estimating the prognosis for patients with VFP remains the most important issue for LEMG. First meta-analyses are now available analyzing which LEMG parameters are the best prognosticators for recovery or persistent palsy. Due to the advances in multichannel LEMG, laryngeal nerve monitoring can now control the recurrent laryngeal nerve and the external branch of the superior laryngeal nerve during thyroid surgery. Finally, also the advances of LEMG for laryngeal pacing, guided laryngeal injections, laryngeal electrostimulation, and other indications beyond otolaryngology are discussed.

Can MRI quantify the volume changes of denervated facial muscles?

Could manual segmentation of magnetic resonance images be used to quantify the effects of transcutaneous electrostimulation and reinnervation of denervated facial muscle? Five patients with unilateral facial paralysis were scanned during the study while receiving a daily surface electrostimulation of the paralytic cheek region, but also after reinnervation. Their facial muscles were identified in 3D (coronal, sagittal, and axial) and segmented in magnetic resonance imaging (MRI) data for in total 28 time points over the 12 months of study. A non-significant trend of increasing muscle volume were detected after reinnervation. MRI is a valuable technique in the facial paralysis research.

Facial nerve electrodiagnostics for patients with facial palsy: a clinical practice guideline.

PURPOSE: Facial nerve electrodiagnostics is a well-established and important tool for decision making in patients with facial nerve diseases. Nevertheless, many otorhinolaryngologist-head and neck surgeons do not routinely use facial nerve electrodiagnostics. This may be due to a current lack of agreement on methodology, interpretation, validity, and clinical application. Electrophysiological analyses of the facial nerve and the mimic muscles can assist in diagnosis, assess the lesion severity, and aid in decision making. With acute facial palsy, it is a valuable tool for predicting recovery. METHODS: This paper presents a guideline prepared by members of the International Head and Neck Scientific Group and of the Multidisciplinary Salivary Gland Society for use in cases of peripheral facial nerve disorders based on a systematic literature search. RESULTS: Required equipment, practical implementation, and interpretation of the results of facial nerve electrodiagnostics are presented. CONCLUSION: The aim of this guideline is to inform all involved parties (i.e. otorhinolaryngologist-head and neck surgeons and other medical specialists, therapeutic professionals and the affected persons) and to provide practical recommendations for the diagnostic use of facial nerve electrodiagnostics.

The effect of adjuvant oral application of honey in the management of postoperative pain after tonsillectomy in adults: A pilot study.

OBJECTIVE: To analyze the effect of adjuvant oral application of honey for treating postoperative pain after tonsillectomy. DESIGN: Single centre prospective cohort study. SETTING: Two cohorts of patients after tonsillectomy. PARTICIPANTS: 56 patients treated with honey 8 times per day (honey group), 18 patients treated without honey (control group); baseline analgesia were non-steroidal anti-inflammatory drugs (NSAID) or coxibs; opioids were used as pro re nata (PRN) medication; mean age 34.4 ± 13.4 years; 36% women. MAIN OUTCOME MEASURES: On first to fifth postoperative day, patients rated their pain using the validated questionnaire of the German-wide project Quality Improvement in Postoperative Pain Treatment (QUIPS) including a numeric rating scale (NRS, 0-10) for determination of patient's pain. QUIPS allows standardized assessment of patients' characteristics andpain-associated patient-reported outcomes (PROs). The influence of preoperative and postoperative parameters on patients' postoperative pain were estimated by univariate and multivariate statistical analysis. RESULTS: Average pain in activity in the control group was greater than 4 (NRS 4.4 ± 2.4) during the first five postoperative days, with a renewed increase in pain intensity on the fifth day (4.3 ± 2.5). In the honey group, the pain in activity decreased without any further pain increase and was only higher than 4 on the first three postoperative days (4.3 ± 2.1, all p>0.05). However; neither minimal nor maximal pain were significantly different between both groups on the first postoperative day (p = 0.217, p = 0.980). Over the five postoperative days, the minimal and maximal pain in the honey group decreased continuously and faster than in the control group. With regard to pain-related impairments on the first day, the honey group reported less pain-related sleep disturbance (p = 0.026), as well as significantly fewer episodes of postoperative oral bleeding (p = 0.028) than the control group. Patients without honey consumption had on the first and fifth postoperative day a higher risk of increased minimal pain (OR = -2.424, CI = -4.075 --0.385). Gender was an independent factor for compliance of honey consumption on the second postoperative day (p = 0.037). Men had a lower probability for compliance of honey consumption (OR = -0.288, CI = -2.863 --0.090). CONCLUSION: There was a trend of reduced postoperative pain after oral honey application. Honey also seems to reduce pain-related impairments. The need for additional opioids on the first day could be reduced. A larger controlled trial is now needed to varify the effect of honey on pain after tonsillectomy. CLINICAL TRIAL REGISTRATION NUMBER: German Clinical Trials Register DRKS00006153. The authors confirm that all ongoing and related trials for this drug/intervention are registered.

Tolerability of facial electrostimulation in healthy adults and patients with facial synkinesis.

PURPOSE: To evaluate optimal stimulation parameters with regard to discomfort and tolerability for transcutaneous electrostimulation of facial muscles in healthy participants and patients with postparetic facial synkinesis. METHODS: Two prospective studies were performed. First, single pulse monophasic stimulation with rectangular pulses was compared to triangular pulses in 48 healthy controls. Second, 30 healthy controls were compared to 30 patients with postparetic facial synkinesis with rectangular pulse form. Motor twitch threshold, tolerability threshold, and discomfort were assessed using a numeric rating scale at both thresholds. RESULTS: Discomfort at motor threshold was significantly lower for rectangular than for triangular pulses. Average motor and tolerability thresholds were higher for patients than for healthy participants. Discomfort at motor threshold was significantly lower for healthy controls compared to patients. Major side effects were not seen. CONCLUSIONS: Surface electrostimulation for selective functional and tolerable facial muscle contractions in patients with postparetic facial synkinesis is feasible.

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.

Surface electrical stimulation for facial paralysis is not harmful.

INTRODUCTION: Does electrical stimulation (ES) of denervated muscles delay or prevent reinnervation, or increase synkinesis? In this retrospective study we evaluate the outcome, with and without ES, of patients with acutely denervated facial muscles. METHODS: The effect of ES was analyzed in two experiments. In the first experiment, 39 patients (6 with home-based ES, median 17.5 months) underwent facial nerve reconstruction surgery. Time to recovery of volitional movements was analyzed. The second experiment involved 13 patients (7 with ES, median 19 months) during spontaneous reinnervation. Sunnybrook and eFACE scores provided functional outcome measures. RESULTS: No difference in time of reinnervation after facial nerve reconstruction surgery was seen between the patients with and without ES (median [interquartile range]: 4.5 [3.0-5.25] vs 5.7 [3.5-9.5] months; P = .2). After spontaneous reinnervation, less synkinesis was noted (Sunnybrook synkinesis score: 3.0 [2.0-3.0] vs 5.5 [4.75-7.0]; P = .02) with ES. DISCUSSION: We find no evidence that ES prevents or delays reinnervation or increases synkinesis in facial paralysis.

Hypersalivation: update of the German S2k guideline (AWMF) in short form.

Hypersalivation describes a relatively excessive salivary flow, which wets the patient himself and his surroundings. It may result because of insufficient oro-motor function, dysphagia, decreased central control and coordination. This update presents recent changes and innovation in the treatment of hypersalivation. Multidisciplinary diagnostic and treatment evaluation is recommended already at early stage and focus on dysphagia, saliva aspiration, and oro-motor deficiencies. Clinical screening tools and diagnostics such as fiberoptic endoscopic evaluation of swallowing generate important data on therapy selection and control. Many cases profit from swallowing therapy programmes to activate compensation mechanisms as long compliances are given. In children with hypotonic oral muscles, oral stimulation plates can induce a relevant symptom release because of the improved lip closure. The pharmacologic treatment improved for pediatric cases as glycopyrrolate fluid solution (Sialanar®) is now indicated for hypersalivation within the EU. The injection of botulinum toxin into the salivary glands has shown safe and effective results with long-lasting saliva reduction. Here, a phase III trial is completed for incobotulinum toxin A and, in the US, is indicated for the treatment of adult patients with chronic hypersalivation. Surgical treatment should be reserved for isolated cases. External radiation is judged as a safe and effective therapy when using modern 3D techniques to minimize tissue damage. Therapy effects and symptom severity have to be followed, especially in cases with underlying neurodegenerative disease.

Brief Electrical Stimulation Improves Functional Recovery After Femoral But Not After Facial Nerve Injury in Rats.

Brief low-frequency electrical stimulation (ES, 1 h, 20 Hz) of the proximal nerve stump has emerged as a potential adjunct treatment for nerve injury. Despite available experimental and clinical data, the potentials and limitations of the ES therapy still have to be defined using different animal models, types of nerves, and clinical settings. Here, we show that brief ES of the proximal stump of the transected rat femoral nerve causes, as estimated by motion analysis, enhanced functional recovery reaching preoperative levels within 5 months of injury, in contrast to the incomplete restoration in sham-stimulated (SS) animals. The functional advantage seen in ES rats was associated with higher numbers, as compared with SS, of correctly targeted quadriceps motoneurons. In contrast, ES prior to facial nerve suture did not lead to improvement of whisking compared with SS. Lack of functional effects of the treatment was correlated with lack of changes, as compared with SS, in the precision of muscle reinnervation and frequency of abnormally innervated muscle fibers. These results show that ES is an effective therapy in a spinal nerve injury model leading to complete restoration of function. Although this finding and the safety of the procedure are encouraging, the results for the facial nerve model suggest that brief ES may not be a universal treatment for nerve injuries. Anat Rec, 302:1304-1313, 2019. © 2019 Wiley Periodicals, Inc.

The accuracy of objective threshold determination at low frequencies: comparison of different auditory brainstem response (ABR) and auditory steady state response (ASSR) methods.

OBJECTIVE: The hearing threshold at 500 Hz was estimated using five methods which are suitable for the low frequency range: Low-Chirp BERA (LCBERA), Notched-noise BERA (NNBERA), Narrow band CE-Chirp BERA (NBCBERA) and Narrow band CE-Chirp ASSR (NBCASSR) (40/90 Hz). The slope of the discrimination function of each method was used for determination of the most efficient method. The threshold values were compared and the corresponding odds ratios (OR) were calculated. DESIGN: All methods were applied to each subject. Stimulus levels were arranged individually. Response detection was carried out by visual inspection of the records in case of BERA and automatically in case of ASSR. Each individual series of recordings was converted to a dichotomous function indicating whether or not a response was discernible and a continuous method-specific discrimination function was constructed. This function was realised by a Boltzmann function whose slope in the inflection point serves as quality measure. Additionally, an OR evaluation was carried out in order to validate the significance of results. STUDY SAMPLE: Twenty five normal hearing adults (aged 18-30 years) were tested. RESULTS: LCBERA proved to have the highest reliability according to the slope of the Boltzmann function, the comparison of threshold values and OR. CONCLUSIONS: The LCBERA is recommended for use in routine clinical practice.

Method to test the long-term stability of functional electrical stimulation via multichannel electrodes (e.g., applicable for laryngeal pacing) and to define best points for stimulation: in vivo animal analysis.

The study aim was to identify and analyze intramuscular electrically sensitive points. Electrically sensitive points are herein defined as positions, which allow muscles stimulation with a minimum possible fatigue for a maximum amount of time. A multichannel array electrode was used which could be interesting to retain the function of larynx muscle after paralysis. Eight array electrodes were implanted in the triceps brachii muscle of four rats. While being under anesthesia, the animals were intramuscularly stimulated at 16 different positions. Sihler's staining technique was used to make visible the nerves routes and the intramuscular position of the individual electrode plate. The positions of the motor end plates were determined by means of multichannel-electromyography. The positions that allow longest stimulation periods are located close to the points where the nerves enter the muscle. Stimulation at the position of the motor end plates does not result in stimulation periods above average. Locations initially causing strong muscle contractions are not necessarily identical to the ones allowing long stimulation periods. The animal model identified the stimulation points for minimal possible muscle fatigue stimulation as being located close to the points of entrance of the nerve into the muscle. Stimulation causing an initially strong contraction response is no indication of optimal location of the stimulation electrode in terms of chronic stimulation. The array electrode of this study could be interesting as a stimulation electrode for a larynx pacemaker.

High variability of facial muscle innervation by facial nerve branches: A prospective electrostimulation study.

OBJECTIVES/HYPOTHESIS: To examine by intraoperative electric stimulation which peripheral facial nerve (FN) branches are functionally connected to which facial muscle functions. STUDY DESIGN: Single-center prospective clinical study. METHODS: Seven patients whose peripheral FN branching was exposed during parotidectomy under FN monitoring received a systematic electrostimulation of each branch starting with 0.1 mA and stepwise increase to 2 mA with a frequency of 3 Hz. The electrostimulation and the facial and neck movements were video recorded simultaneously and evaluated independently by two investigators. RESULTS: A uniform functional allocation of specific peripheral FN branches to a specific mimic movement was not possible. Stimulation of the whole spectrum of branches of the temporofacial division could lead to eye closure (orbicularis oculi muscle function). Stimulation of the spectrum of nerve branches of the cervicofacial division could lead to reactions in the midface (nasal and zygomatic muscles) as well as around the mouth (orbicularis oris and depressor anguli oris muscle function). Frontal and eye region were exclusively supplied by the temporofacial division. The region of the mouth and the neck was exclusively supplied by the cervicofacial division. Nose and zygomatic region were mainly supplied by the temporofacial division, but some patients had also nerve branches of the cervicofacial division functionally supplying the nasal and zygomatic region. CONCLUSIONS: FN branches distal to temporofacial and cervicofacial division are not necessarily covered by common facial nerve monitoring. Future bionic devices will need a patient-specific evaluation to stimulate the correct peripheral nerve branches to trigger distinct muscle functions. LEVEL OF EVIDENCE: 4 Laryngoscope, 127:1288-1295, 2017.