An electrophysiologic model for functional assessment of effects of neurotrophic factors on facial nerve reinnervation.
OBJECTIVE
To establish a sound objective model for assessing the effects of neurotrophic factors on facial nerve function after injury and to compare the effects of brain-derived neurotrophic factor (BDNF) with its neutralizing antibody on facial nerve function after injury.


METHODS
Prospective electrophysiologic analysis of recovery of function 4 weeks after axotomy involving facial nerve transection and primary end-to-end reanastomosis in adult rats and blind comparison with randomized intramuscular injection of either BDNF, monoclonal antibody to BDNF in neutralizing concentration, or control solution.


RESULTS
There were no statistically significant differences between groups in latencies, duration, amplitude, area, or conduction velocity before axotomy, and recorded conduction velocities were consistent with previously reported values, which suggests that the recordings were reliable and reproducible. After transection, there was a mean increase in latency 1 and decreases in latency 2, integrated average area, muscle action potential duration, amplitude, and conduction velocity for all 3 groups. When the groups were compared after transection, the anti-BDNF group showed a significant decrease in conduction velocity and muscle action potential duration (Kruskal-Wallis P = .01 and P = .008, respectively) compared with the other groups. There were no statistically significant differences in latencies, amplitude, or area among the groups.


CONCLUSIONS
We have established an electrophysiologic model for objective assessment of facial nerve function in the rat. Future studies should combine functional electrophysiologic assessment and histologic examination to provide a more robust model for studying the effects of neurotrophic factors on facial nerve reinnervation and synkinesis.
Byrne
Patrick J
PJ
Division of Facial Plastic and Reconstructive Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21287-1910, USA. pbyrne2@jhmi.edu
Stuart
R Morgan
RM
Fakhry
Carole
C
Lehar
Mohammed
M
Flint
Paul W
PW
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology*; D004594:Electrophysiology; D005154:Facial Nerve / Q000601:surgery*; D008297:Male; D009416:Nerve Regeneration / Q000187:drug effects* / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function; D018709:Statistics, Nonparametric
D019208:Brain-Derived Neurotrophic Factor