title: Fluorescent retrograde axonal tracing of the facial nerve.
abstract: OBJECTIVE
  The objective of this study was to investigate retrograde fluorescent axonal labeling of motor nerves as an aid to surgical dissection in otolaryngology-head and neck surgery.
  
  
  METHODS
  Cholera toxin B subunit conjugated to a fluorescent dye was injected into the facial musculature of New Zealand white rabbits. At variable time points after injection, the facial nerves were harvested and analyzed for fluorescence in the peripheral axon.
  
  
  RESULTS
  All injected animals demonstrated axonal fluorescence. No animal demonstrated facial weakness. Fluorescence was detected a maximum of 20 mm from the distal end of the nerve. Time periods greater than 48 hours did not substantially increase transport distance.
  
  
  CONCLUSIONS
  Cholera toxin B subunit fluorescent conjugates, when administered intramuscularly, reliably label the distal portion of the facial nerve. In vivo labeling of a motor nerve may have significant potential for identifying a nerve in surgery. This work represents a preliminary investigation into the adaptation of in vivo fluorescence techniques as an aid to surgical dissection. Further research to refine this technique should be supported.
authors.affiliation: Vanderbilt University Department of Hearing and Speech Sciences, Nashville, Tennessee, USA. matthew.o.malley@vanderbilt.edu
authors.forename: Matthew R
authors.initials: MR
authors.lastname: O'Malley
authors.forename: Justin E
authors.initials: JE
authors.lastname: Wittkopf
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Cutler
authors.forename: Robert F
authors.initials: RF
authors.lastname: Labadie
authors.forename: Troy A
authors.initials: TA
authors.lastname: Hackett
authors.forename: David S
authors.initials: DS
authors.lastname: Haynes
mesh_terms: D000818:Animals; D001369:Axons / Q000648:ultrastructure*; D002772:Cholera Toxin; D005152:Facial Muscles / Q000294:innervation; D005154:Facial Nerve / Q000033:anatomy & histology*; D005260:Female; D005456:Fluorescent Dyes; D007091:Image Processing, Computer-Assisted; D007273:Injections, Intramuscular; D008297:Male; D008856:Microscopy, Fluorescence; D009046:Motor Neurons / Q000166:cytology*; D009434:Neural Pathways / Q000033:anatomy & histology; D011817:Rabbits; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D002772:Cholera Toxin