title: High variability of facial muscle innervation by facial nerve branches: A prospective electrostimulation study.
abstract: To examine by intraoperative electric stimulation which peripheral facial nerve (FN) branches are functionally connected to which facial muscle functions.
  
  
  
  Single-center prospective clinical study.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  4 Laryngoscope, 127:1288-1295, 2017.
authors.affiliation: Department of Otorhinolaryngology and Facial Nerve Center Jena, Jena University Hospital, Jena, Germany.
authors.forename: Ashraf
authors.initials: A
authors.lastname: Raslan
authors.affiliation: Department of Otorhinolaryngology and Facial Nerve Center Jena, Jena University Hospital, Jena, Germany.
authors.forename: Gerd Fabian
authors.initials: GF
authors.lastname: Volk
authors.affiliation: Department of Otorhinolaryngology and Facial Nerve Center Jena, Jena University Hospital, Jena, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Möller
authors.affiliation: University of Applied Sciences Technikum Wien, Vienna, Austria.
authors.forename: Vincent
authors.initials: V
authors.lastname: Stark
authors.affiliation: University of Applied Sciences Technikum Wien, Vienna, Austria.
authors.forename: Nikolas
authors.initials: N
authors.lastname: Eckhardt
authors.affiliation: Department of Otorhinolaryngology and Facial Nerve Center Jena, Jena University Hospital, Jena, Germany.
authors.forename: Orlando
authors.identifier: 0000-0001-9671-0784
authors.initials: O
authors.lastname: Guntinas-Lichius
mesh_terms: D002610:Cheek / Q000294:innervation; D004558:Electric Stimulation / Q000379:methods*; D005143:Eyelids / Q000294:innervation; D005145:Face / Q000294:innervation; D005152:Facial Muscles / Q000294:innervation* / Q000601:surgery; D005154:Facial Nerve / Q000502:physiology* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008410:Masticatory Muscles / Q000294:innervation; D008875:Middle Aged; D009055:Mouth / Q000294:innervation; D009915:Orbit / Q000294:innervation; D010306:Parotid Gland / Q000601:surgery; D011446:Prospective Studies
keywords: Electrostimulation; communication; facial movements; facial nerve branches; mimetic muscles; monitoring; nerve course; nerve innervation