title: Induction of facial muscle neurotization by temporalis muscle transposition: literature review and animal model evaluation using horseradish peroxidase uptake.
abstract: OBJECTIVE
  To study the concept of facial muscle reinnervation from the trigeminal pathway following facial nerve paralysis.
  
  
  METHODS
  We studied this phenomenon in an animal model using the neuronal marker, horseradish peroxidase (HRP). The temporalis transposition procedure was performed at varying intervals post facial nerve transection. To evaluate the trigeminal-facial reinnervation process and its timing, the zygomaticus major muscle was injected with HRP at varied periods after temporalis transposition, and histologic sections of the brainstem nuclei were examined for the final location of the HRP.
  
  
  RESULTS
  The presence of HRP in the trigeminal nucleus provided evidence of trigeminal-facial neurotization in those animals that underwent temporalis transposition up to 2 months following facial denervation and in which the HRP injection was performed 4 months after temporalis transposition.
  
  
  CONCLUSIONS
  The findings of our pilot study are strongly supportive of the trigeminal-facial neurotization hypothesis in those animals that underwent temporalis transposition up to 2 months post facial denervation and in which 4 months were allowed thereafter for adequate neurite ingrowth and neurotization to occur. This suggests that the neurotrophic signals are greatest up to 2 months post denervation and denotes the optimal time for performance of reconstructive procedures. Future studies with a larger number of animals in each group will be necessary to ensure more potent statistical significance and to augment our experimental evidence that trigeminal-facial crossover does occur and can be used as an adjunctive concept to maximize early rehabilitation of the paralyzed face.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02114, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Petropoulos
authors.forename: M L
authors.initials: ML
authors.lastname: Cheney
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D004195:Disease Models, Animal; D005152:Facial Muscles / Q000294:innervation* / Q000601:surgery; D005154:Facial Nerve / Q000473:pathology; D005158:Facial Paralysis / Q000601:surgery; D006168:Guinea Pigs; D006735:Horseradish Peroxidase / Q000032:analysis; D008297:Male; D016067:Nerve Transfer; D009434:Neural Pathways / Q000473:pathology; D016501:Neurites / Q000648:ultrastructure; D010865:Pilot Projects; D013524:Surgical Flaps; D013703:Temporal Muscle / Q000294:innervation / Q000637:transplantation*; D014276:Trigeminal Nerve / Q000473:pathology / Q000601:surgery*; D014278:Trigeminal Nuclei / Q000473:pathology
chemical_list: D015415:Biomarkers; D006735:Horseradish Peroxidase