{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T19:32:59Z","timestamp":1781206379232,"version":"3.54.1"},"reference-count":63,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2023,10,16]],"date-time":"2023-10-16T00:00:00Z","timestamp":1697414400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Rehabil. Sci."],"abstract":"<jats:sec><jats:title>Introduction<\/jats:title><jats:p>Although many different treatments were developed for facial palsy, only a few therapeutic options are available for facial synkinesis. Electrical stimulation of specific muscles via implants could be useful in restoring facial symmetry in synkinetic patients. A challenge in developing stimulation devices is finding the right stimulation location, type, and amplitude. This work assesses the ability to selectively stimulate the zygomaticus muscle (ZYG) in patients with oral-ocular synkinesis to elicit a visually detectable response of the ipsilateral corner of the mouth (COM), without causing a reaction of the orbicularis oculi muscle (OOM). We aimed to assess how close to the COM the stimulation should be delivered in order to be selective.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>A total of 10 patients (eight females, two males) were enrolled. Facial function was graded according to the Sunnybrook facial grading system. Needle EMG was used to test the activities of the muscles, during volitional and \u201cunintended\u201d movements, and the degree of synkinesis of the ZYG and OOM. Two ball electrodes connected to an external stimulator were placed on the paretic ZYG, as close as possible to the COM.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Independent of the waveform with which the stimulation was presented, a selective ZYG response was observed within 4.5\u2005cm of the horizontal plane and 3\u2005cm of the vertical plane of the COM. When the distance between the electrodes was kept to \u22642\u2005cm, the amplitude necessary to trigger a response ranged between 3 and 6\u2005mA when the stimulation was delivered with triangular pulses and between 2.5 and 3.5\u2005mA for rectangular pulses. The required amplitude did not seem to be dependent on the applied phase duration (PD), as long as the PD was \u22655\u2005ms.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Our results show that selective stimulation of the ZYG presenting synkinetic ZYG\u2013OOM reinnervation can be achieved using a broad PD range (25\u20131,000\u2005ms) and an average amplitude \u22646\u2005mA, which may be further decreased to 3.5\u2005mA if the stimulation is delivered via rectangular rather than triangular waves. The most comfortable and effective results were observed with PDs between 50 and 250\u2005ms, suggesting that this range should be selected in future studies.<\/jats:p><\/jats:sec><jats:sec><jats:title>Clinical Trial Registration<\/jats:title><jats:p>[<jats:ext-link>https:\/\/drks.de\/search\/de\/trial\/DRKS00019992<\/jats:ext-link>], identifier (DRKS00019992).<\/jats:p><\/jats:sec>","DOI":"10.3389\/fresc.2023.1205154","type":"journal-article","created":{"date-parts":[[2023,10,16]],"date-time":"2023-10-16T05:15:51Z","timestamp":1697433351000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":3,"title":["Selective zygomaticus muscle activation by ball electrodes in synkinetically reinnervated patients after facial paralysis"],"prefix":"10.3389","volume":"4","author":[{"given":"Dirk","family":"Arnold","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jovanna","family":"Thielker","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carsten M.","family":"Klingner","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Orlando","family":"Guntinas-Lichius","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gerd Fabian","family":"Volk","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2023,10,16]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"273","DOI":"10.1016\/j.otc.2015.10.002","article-title":"Facial nerve and parotid gland anatomy","volume":"49","author":"Kochhar","year":"2016","journal-title":"Otolaryngol Clin North Am"},{"key":"B2","doi-asserted-by":"publisher","first-page":"1318","DOI":"10.1097\/prs.0000000000001244","article-title":"Anatomical considerations to prevent facial nerve injury","volume":"135","author":"Roostaeian","year":"2015","journal-title":"Plast Reconstr Surg"},{"key":"B3","doi-asserted-by":"publisher","first-page":"2708","DOI":"10.1002\/lary.28500","article-title":"Facial nerve branching patterns vary with vascular anomalies","volume":"130","author":"Adidharma","year":"2020","journal-title":"Laryngoscope"},{"key":"B4","doi-asserted-by":"publisher","first-page":"1288","DOI":"10.1002\/lary.26349","article-title":"High variability of facial muscle innervation by facial nerve branches: a prospective electrostimulation study","volume":"127","author":"Raslan","year":"2017","journal-title":"Laryngoscope"},{"key":"B5","doi-asserted-by":"publisher","first-page":"560","DOI":"10.1002\/ca.23044","article-title":"The nerve supply of zygomaticus major: variability and distinguishing zygomatic from buccal facial nerve branches","volume":"31","author":"Kehrer","year":"2018","journal-title":"Clin Anat"},{"key":"B6","doi-asserted-by":"publisher","first-page":"480","DOI":"10.1002\/ca.23332","article-title":"Anatomical study of the zygomatic and buccal branches of the facial nerve: application to facial reanimation procedures","volume":"32","author":"Kehrer","year":"2019","journal-title":"Clin Anat"},{"key":"B7","doi-asserted-by":"publisher","first-page":"31","DOI":"10.1016\/S1042-3680(18)30755-1","article-title":"Peripheral nerve regeneration","volume":"2","author":"Liuzzi","year":"1991","journal-title":"Neurosurg Clin N Am"},{"key":"B8","doi-asserted-by":"publisher","first-page":"784","DOI":"10.1046\/j.1445-2197.2003.02799.x","article-title":"Vocal cord paralysis, synkinesis and vocal fold motion impairment","volume":"73","author":"Benjamin","year":"2003","journal-title":"ANZ J Surg"},{"key":"B9","doi-asserted-by":"publisher","first-page":"1289","DOI":"10.1097\/prs.0000000000001802","article-title":"Epidemiologic overview of synkinesis in 353 patients with longstanding facial paralysis under treatment with botulinum toxin for 11 years","volume":"136","author":"Salles","year":"2015","journal-title":"Plast Reconstr Surg"},{"key":"B10","doi-asserted-by":"publisher","first-page":"147","DOI":"10.1159\/000008154","article-title":"The development of synkinesis after facial nerve paralysis","volume":"43","author":"Celik","year":"2000","journal-title":"Eur Neurol"},{"key":"B11","doi-asserted-by":"publisher","first-page":"1847","DOI":"10.1288\/00005537-197911000-00020","article-title":"Mechanisms of synkinesis","volume":"89","author":"Crumley","year":"1979","journal-title":"Laryngoscope"},{"key":"B12","doi-asserted-by":"publisher","first-page":"829","DOI":"10.1007\/bf01611989","article-title":"Survival and subsequent regeneration of olfactory neurons after a distal axonal lesion","volume":"16","author":"Cancalon","year":"1987","journal-title":"J Neurocytol"},{"key":"B13","doi-asserted-by":"publisher","first-page":"539","DOI":"10.1016\/s0194-59980223254-4","article-title":"Biofeedback rehabilitation for prevention of synkinesis after facial palsy","volume":"128","author":"Nakamura","year":"2003","journal-title":"Otolaryngol Head Neck Surg"},{"key":"B14","doi-asserted-by":"publisher","first-page":"58","DOI":"10.23736\/s1973-9087.19.05757-5","article-title":"Give me a kiss! An integrative rehabilitative training program with motor imagery and mirror therapy for recovery of facial palsy","volume":"56","author":"Paolucci","year":"2020","journal-title":"Eur J Phys Rehabil Med"},{"key":"B15","doi-asserted-by":"publisher","first-page":"190","DOI":"10.1097\/sap.0000000000001908","article-title":"Depression rates after facial paralysis","volume":"83","author":"Saadi","year":"2019","journal-title":"Ann Plast Surg"},{"key":"B16","doi-asserted-by":"publisher","first-page":"12","DOI":"10.1186\/s11689-019-9272-2","article-title":"Children with facial paralysis due to Moebius syndrome exhibit reduced autonomic modulation during emotion processing","volume":"11","author":"De Stefani","year":"2019","journal-title":"J Neurodev Disord"},{"key":"B17","doi-asserted-by":"publisher","first-page":"9","DOI":"10.1055\/s-0032-1327624","article-title":"Emotional impact of facial palsy","volume":"92","author":"Dobel","year":"2013","journal-title":"Laryngorhinootologie"},{"key":"B18","doi-asserted-by":"publisher","first-page":"E2518","DOI":"10.1002\/lary.29526","article-title":"Role of body dysmorphic disorder in patients with postparalytic facial synkinesis","volume":"131","author":"Volk","year":"2021","journal-title":"Laryngoscope"},{"key":"B19","doi-asserted-by":"publisher","first-page":"686","DOI":"10.1007\/s00106-018-0542-1","article-title":"Newly developed biofeedback program for facial muscle training in patients with facial paralysis","volume":"66","author":"Bernd","year":"2018","journal-title":"Hno"},{"key":"B20","doi-asserted-by":"publisher","first-page":"e012628","DOI":"10.1136\/bmjopen-2016-012628","article-title":"Prevalence and associated factors of facial palsy and lifestyle characteristics: data from the Korean National Health and Nutrition Examination Survey 2010\u20132012","volume":"6","author":"Chang","year":"2016","journal-title":"BMJ Open"},{"key":"B21","doi-asserted-by":"publisher","first-page":"1516","DOI":"10.1002\/lary.25695","article-title":"Nonmotor disabilities in patients with facial palsy measured by patient-reported outcome measures","volume":"126","author":"Volk","year":"2016","journal-title":"Laryngoscope"},{"key":"B22","doi-asserted-by":"publisher","first-page":"59","DOI":"10.1298\/ptr.E10000","article-title":"Effect of muscle strengthening on peripheral facial palsy: a randomized controlled trial","volume":"23","author":"Morishima","year":"2020","journal-title":"Phys Ther Res"},{"key":"B23","doi-asserted-by":"publisher","first-page":"203","DOI":"10.1080\/00016489.2020.1842905","article-title":"The mirror effect plus protocol for acute Bell\u2019s palsy: a randomised and longitudinal study on facial rehabilitation","volume":"141","author":"Martineau","year":"2021","journal-title":"Acta Otolaryngol"},{"key":"B24","doi-asserted-by":"publisher","first-page":"1037","DOI":"10.1097\/01.mao.0000217350.09796.07","article-title":"Stability of benefits of mime therapy in sequelae of facial nerve paresis during a 1-year period","volume":"27","author":"Beurskens","year":"2006","journal-title":"Otol Neurotol"},{"key":"B25","doi-asserted-by":"publisher","first-page":"1","DOI":"10.3390\/diagnostics12030565","article-title":"Kabat rehabilitation in facial nerve palsy after parotid gland tumor surgery: a case-control study","volume":"12","author":"Boschetti","year":"2022","journal-title":"Diagnostics (Basel)"},{"key":"B26","doi-asserted-by":"publisher","first-page":"649","DOI":"10.1177\/0269215510395634","article-title":"Facial exercise therapy for facial palsy: systematic review and meta-analysis","volume":"25","author":"Pereira","year":"2011","journal-title":"Clin Rehabil"},{"key":"B27","doi-asserted-by":"publisher","first-page":"1065","DOI":"10.1001\/jamaoto.2020.3049","article-title":"Physical therapy for iatrogenic facial paralysis: a systematic review","volume":"146","author":"Wamkpah","year":"2020","journal-title":"JAMA Otolaryngol Head Neck Surg"},{"key":"B28","doi-asserted-by":"publisher","first-page":"25","DOI":"10.1186\/1746-160x-6-25","article-title":"Modern concepts in facial nerve reconstruction","volume":"6","author":"Volk","year":"2010","journal-title":"Head Face Med"},{"key":"B29","doi-asserted-by":"publisher","first-page":"1","DOI":"10.3390\/jcm11102890","article-title":"A comprehensive approach to facial reanimation: a systematic review","volume":"11","author":"Pinkiewicz","year":"2022","journal-title":"J Clin Med"},{"key":"B30","doi-asserted-by":"publisher","first-page":"e19152","DOI":"10.1097\/md.0000000000019152","article-title":"Neuromuscular electrical stimulation and shortwave diathermy in unrecovered bell palsy: a randomized controlled study","volume":"99","author":"Marotta","year":"2020","journal-title":"Medicine (Baltimore)"},{"key":"B31","doi-asserted-by":"publisher","first-page":"347","DOI":"10.1002\/mus.26784","article-title":"Surface electrical stimulation for facial paralysis is not harmful","volume":"61","author":"Puls","year":"2020","journal-title":"Muscle Nerve"},{"key":"B32","doi-asserted-by":"publisher","first-page":"717","DOI":"10.1002\/mus.26460","article-title":"Functional electrical stimulation following nerve injury in a large animal model","volume":"59","author":"Cercone","year":"2019","journal-title":"Muscle Nerve"},{"key":"B33","doi-asserted-by":"publisher","first-page":"876","DOI":"10.1111\/aor.12624","article-title":"Effects of functional electrical stimulation on denervated laryngeal muscle in a large animal model","volume":"39","author":"Cheetham","year":"2015","journal-title":"Artif Organs"},{"key":"B34","doi-asserted-by":"publisher","first-page":"1","DOI":"10.3389\/fneur.2022.1019554","article-title":"Pathogenesis, diagnosis and therapy of facial synkinesis: a systematic review and clinical practice recommendations by the international head and neck scientific group","volume":"13","author":"Guntinas-Lichius","year":"2022","journal-title":"Front Neurol"},{"key":"B35","doi-asserted-by":"publisher","first-page":"833","DOI":"10.1016\/j.bjps.2017.01.009","article-title":"Botulinum toxin treatment for facial palsy: a systematic review","volume":"70","author":"Cooper","year":"2017","journal-title":"J Plast Reconstr Aesthet Surg"},{"key":"B36","doi-asserted-by":"publisher","first-page":"71","DOI":"10.1016\/j.bjps.2014.08.067","article-title":"Half-mirror biofeedback exercise in combination with three botulinum toxin A injections for long-lasting treatment of facial sequelae after facial paralysis","volume":"68","author":"Lee","year":"2015","journal-title":"J Plast Reconstr Aesthet Surg"},{"key":"B37","first-page":"810","article-title":"Long-term facial improvement after repeated BoNT-A injections and mirror biofeedback exercises for chronic facial synkinesis: a case-series study","volume":"52","author":"Mandrini","year":"2016","journal-title":"Eur J Phys Rehabil Med"},{"key":"B38","doi-asserted-by":"publisher","first-page":"1922","DOI":"10.1097\/00006534-199706000-00017","article-title":"Facial neuromuscular retraining for oral synkinesis","volume":"99","author":"Brach","year":"1997","journal-title":"Plast Reconstr Surg"},{"key":"B39","doi-asserted-by":"publisher","first-page":"2370","DOI":"10.1097\/01.Prs.0000061007.36637.88","article-title":"Changes in facial movement and synkinesis with facial neuromuscular reeducation","volume":"111","author":"VanSwearingen","year":"2003","journal-title":"Plast Reconstr Surg"},{"key":"B40","doi-asserted-by":"publisher","first-page":"746188","DOI":"10.3389\/fresc.2021.746188","article-title":"Effect of an intensified combined electromyography and visual feedback training on facial grading in patients with post-paralytic facial synkinesis","volume":"2","author":"Volk","year":"2021","journal-title":"Front Rehabil Sci"},{"key":"B41","doi-asserted-by":"publisher","first-page":"1247","DOI":"10.1007\/s00405-020-05818-x","article-title":"Tolerability of facial electrostimulation in healthy adults and patients with facial synkinesis","volume":"277","author":"Volk","year":"2020","journal-title":"Eur Arch Otorhinolaryngol"},{"key":"B42","doi-asserted-by":"publisher","first-page":"1","DOI":"10.3390\/diagnostics11020188","article-title":"Selective surface electrostimulation of the denervated zygomaticus muscle","volume":"11","author":"Arnold","year":"2021","journal-title":"Diagnostics (Basel)"},{"key":"B43","doi-asserted-by":"publisher","first-page":"3576","DOI":"10.1109\/embc.2012.6346739","article-title":"A simulation study: effect of the inter-electrode distance, electrode size and shape in transcutaneous electrical stimulation","volume":"2012","author":"Gomez-Tames","year":"2012","journal-title":"Annu Int Conf IEEE Eng Med Biol Soc"},{"key":"B44","doi-asserted-by":"publisher","first-page":"155","DOI":"10.1080\/03091902.2019.1637470","article-title":"Facial muscle reanimation by transcutaneous electrical stimulation for peripheral facial nerve palsy","volume":"43","author":"M\u00e4kel\u00e4","year":"2019","journal-title":"J Med Eng Technol"},{"key":"B45","doi-asserted-by":"publisher","first-page":"ORL-812","DOI":"10.1177\/019459987808600528","article-title":"Contralaterally elicited electrical stimulation of paralyzed facial muscles","volume":"86","author":"Tobey","year":"1978","journal-title":"Otolaryngology"},{"key":"B46","doi-asserted-by":"publisher","first-page":"241","DOI":"10.1002\/micr.1047","article-title":"Muscle preservation using an implantable electrical system after nerve injury and repair","volume":"21","author":"Nicolaidis","year":"2001","journal-title":"Microsurgery"},{"key":"B47","doi-asserted-by":"publisher","first-page":"4","DOI":"10.1038\/s41528-020-0067-z","article-title":"Conducting polymer tattoo electrodes in clinical electro- and magneto-encephalography","volume":"4","author":"Ferrari","year":"2020","journal-title":"NPJ Flexible Electronics"},{"key":"B48","doi-asserted-by":"publisher","first-page":"1700771","DOI":"10.1002\/advs.201700771","article-title":"Ultraconformable temporary tattoo electrodes for electrophysiology","volume":"5","author":"Ferrari","year":"2018","journal-title":"Adv Sci (Weinh)"},{"key":"B49","doi-asserted-by":"publisher","first-page":"1389","DOI":"10.1109\/tbme.2020.3032354","article-title":"Performance evaluation of a wearable tattoo electrode suitable for high-resolution surface electromyogram recording","volume":"68","author":"Chandra","year":"2021","journal-title":"IEEE Trans Biomed Eng"},{"key":"B50","doi-asserted-by":"publisher","first-page":"380","DOI":"10.1016\/s0194-59989670206-1","article-title":"Development of a sensitive clinical facial grading system","volume":"114","author":"Ross","year":"1996","journal-title":"Otolaryngol Head Neck Surg"},{"key":"B51","doi-asserted-by":"publisher","first-page":"1855","DOI":"10.1007\/s00405-020-05949-1","article-title":"Facial nerve electrodiagnostics for patients with facial palsy: a clinical practice guideline","volume":"277","author":"Guntinas-Lichius","year":"2020","journal-title":"Eur Arch Otorhinolaryngol"},{"key":"B52","doi-asserted-by":"publisher","first-page":"208","DOI":"10.2310\/7070.2001.20148","article-title":"Reliability of the Sunnybrook facial grading system by novice users","volume":"30","author":"Hu","year":"2001","journal-title":"J Otolaryngol"},{"key":"B53","doi-asserted-by":"publisher","first-page":"14","DOI":"10.1016\/j.clindermatol.2013.05.022","article-title":"Facial anatomy","volume":"32","author":"Marur","year":"2014","journal-title":"Clin Dermatol"},{"key":"B54","doi-asserted-by":"publisher","first-page":"241","DOI":"10.1016\/S0094-1298(20)30965-2","article-title":"Surgical anatomy of the facial nerve","volume":"22","author":"Gosain","year":"1995","journal-title":"Clin Plast Surg"},{"key":"B55","first-page":"677","article-title":"The anatomy of the facial nerve","volume":"69","author":"Monkhouse","year":"1990","journal-title":"Ear Nose Throat J"},{"key":"B56","doi-asserted-by":"publisher","first-page":"10","DOI":"10.1002\/ca.21072","article-title":"Peripheral facial nerve communications and their clinical implications","volume":"24","author":"Diamond","year":"2011","journal-title":"Clin Anat"},{"key":"B57","doi-asserted-by":"publisher","first-page":"479","DOI":"10.1016\/S0030-6665(20)31112-9","article-title":"The anatomy of the facial nerve","volume":"24","author":"Proctor","year":"1991","journal-title":"Otolaryngol Clin North Am"},{"key":"B58","doi-asserted-by":"publisher","first-page":"137","DOI":"10.1016\/j.expneurol.2016.02.020","article-title":"Comparison of trophic factors\u2019 expression between paralyzed and recovering muscles after facial nerve injury. A quantitative analysis in time course","volume":"279","author":"Grosheva","year":"2016","journal-title":"Exp Neurol"},{"key":"B59","doi-asserted-by":"publisher","first-page":"394","DOI":"10.1097\/MLG.0b013e31815d8e68","article-title":"Prognostic value of electroneurography and electromyography in facial palsy","volume":"118","author":"Grosheva","year":"2008","journal-title":"Laryngoscope"},{"key":"B60","doi-asserted-by":"publisher","first-page":"391","DOI":"10.1111\/j.1460-9568.2005.03877.x","article-title":"Factors limiting motor recovery after facial nerve transection in the rat: combined structural and functional analyses","volume":"21","author":"Guntinas-Lichius","year":"2005","journal-title":"Eur J Neurosci"},{"key":"B61","doi-asserted-by":"publisher","first-page":"458","DOI":"10.1109\/tbme.1985.325456","article-title":"The strength-duration curve","volume":"32","author":"Geddes","year":"1985","journal-title":"IEEE Trans Biomed Eng"},{"key":"B62","doi-asserted-by":"publisher","first-page":"102485","DOI":"10.1016\/j.jelekin.2020.102485","article-title":"Quantitative analysis of movements in facial nerve palsy with surface electromyography and kinematic analysis","volume":"56","author":"Demeco","year":"2021","journal-title":"J Electromyogr Kinesiol"},{"key":"B63","doi-asserted-by":"publisher","first-page":"179","DOI":"10.3233\/shti220433","article-title":"Automatic objective severity grading of peripheral facial palsy using 3D radial curves extracted from point clouds","volume":"294","author":"B\u00fcchner","year":"2022","journal-title":"Stud Health Technol Inform"}],"container-title":["Frontiers in Rehabilitation Sciences"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fresc.2023.1205154\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,10,16]],"date-time":"2023-10-16T05:15:55Z","timestamp":1697433355000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fresc.2023.1205154\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,10,16]]},"references-count":63,"alternative-id":["10.3389\/fresc.2023.1205154"],"URL":"https:\/\/doi.org\/10.3389\/fresc.2023.1205154","relation":{},"ISSN":["2673-6861"],"issn-type":[{"value":"2673-6861","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,10,16]]},"article-number":"1205154"}}