title: Rodent facial nerve recovery after selected lesions and repair techniques.
abstract: BACKGROUND
  Measuring rodent facial movements is a reliable method for studying recovery from facial nerve manipulation and for examining the behavioral correlates of aberrant regeneration. The authors quantitatively compared recovery of vibrissal and ocular function following three types of clinically relevant nerve injury.
  
  
  METHODS
  One hundred seventy-eight adult rats underwent facial nerve manipulation and testing. In the experimental groups, the left facial nerve was either crushed, transected, and repaired epineurially, or transected and the stumps suture-secured into a tube with a 2-mm gap between them. Facial recovery was measured for the ensuing 1 to 4 months. Data were analyzed for whisking recovery. Previously developed markers of co-contraction of the upper and midfacial zones (possible synkinesis markers) were also examined.
  
  
  RESULTS
  Animals in the crush groups recovered nearly normal whisking parameters within 25 days. The distal branch crush group showed improved recovery over the main trunk crush group for several days during early recovery. By week 9, the transection/repair groups showed evidence of recovery that trended further upward throughout the study period. The entubulation groups followed a similar recovery pattern, although they did not maintain significant recovery levels by the study conclusion. Markers of potential synkinesis increased in selected groups following facial nerve injury.
  
  
  CONCLUSIONS
  Rodent vibrissal function recovers in a predictable fashion following manipulation. Generalized co-contraction of the upper and midfacial zones emerges following facial nerve manipulation, possibly related to aberrant regeneration, polyterminal axons, or hypersensitivity of the rodent to sensory stimuli following nerve manipulation.
authors.affiliation: Boston, Mass.; and St. Louis, Mo. From the Department of Otology and Laryngology, Massachusetts Eye and Ear Infirmary, the Department of Surgery, Massachusetts General Hospital, Harvard Medical School, and the Division of Plastic and Reconstructive Surgery, Washington University School of Medicine.
authors.forename: Tessa A
authors.initials: TA
authors.lastname: Hadlock
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kowaleski
authors.forename: David
authors.initials: D
authors.lastname: Lo
authors.forename: Susan E
authors.initials: SE
authors.lastname: Mackinnon
authors.forename: James T
authors.initials: JT
authors.lastname: Heaton
mesh_terms: D000818:Animals; D001767:Blinking / Q000502:physiology; D005154:Facial Nerve / Q000601:surgery*; D020220:Facial Nerve Injuries / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D023421:Models, Animal; D009431:Neural Conduction / Q000502:physiology; D010525:Peripheral Nerves / Q000601:surgery; D051381:Rats; D017208:Rats, Wistar; D020127:Recovery of Function / Q000502:physiology; D014738:Vibrissae / Q000294:innervation / Q000502:physiology*