Floor plan - 2013 Annual Meeting - American Association for Hand ...

AAHS/ASPN/ASRM OUTSTANDING
NERVE PAPER PRESENTATIONS
Rodent Facial Nerve: a Model for the Study of Synkinesis
Institution where the work was prepared: Massachusetts Eye and Ear Infirmary, Boston, MA, USA
Tessa A. Hadlock, MD1; Jeffrey Kowaleski1; David Lo1; Susan Mackinnon2; James T. Heaton, PhD3; (1)Massachusetts
Eye and Ear Infirmary and Harvard Medical School, (2)Washington University in St. Louis, (3)Massachusetts General
Hospital
INTRODUCTION:
Rodent whisker movement has been measured after facial nerve manipulation, in an attempt to quantify functional recovery. We have
recently established a method of simultaneously monitoring both whisking movement and induced ocular closure, for the purpose of
studying aberrant regeneration. Herein we describe normal bilateral whisking movement and air puff-induced eye closure, and the relationship
between these two distinct facial movements, in a group of normal rats.
MATERIALS / METHODS:
80 female Wistar rats underwent implantation of a head fixation device, followed by quantitative facial movement testing in an apparatus
designed to measure vibrissial movement and ocular closure for each side independently. Animals were handled daily, and then
conditioned to the apparatus. On the day of testing, each animal underwent a 300 second recording session, in which right and left C-
1 whisker positions were continuously recorded, and infrared (IR) emitter/detectors positioned in front of each eye recorded changes
in the IR detection corresponding to eye closure were continuously recorded. An olfactory stimulus was delivered in 10 second pulses
three times at random during the run, and three separate 20 millisecond air puffs were delivered to each eye at random to elicit a blink.
All whisks greater than 15 degrees were analyzed via the method of Bermejo et al, and all eye closures with greater than a 100mV
change in IR detection were counted as blinks.
RESULTS:
Animals tolerated the testing apparatus well. Average whisking amplitude was 35 degrees (sd = 7), consistent with literature values, and
there was no significant difference between whisking frequency, amplitude, velocity, or acceleration between the right and left sides.
Air puff delivery elicited an ipsilateral blink 97% of the time, and a contralateral blink 34% of the time. Olfactory stimulus delivery prompted
a distinct change in whisking behavior 69% of the time, and prompted at least one meaningful eye closure 20% of the time. Air puff
delivery to the eye produced a bilateral whisking burst 85% of the time, indicating that most often air puff delivery elicits whisking as
well as eye closure.
CONCLUSION:
Our study establishes normative data for assessing cranial nerve VII-controlled facial movement in four separate facial regions. We
demonstrate the capability of animals to move their orbicularis oculi muscles independently of and simultaneously with their midfacial
muscles. This model provides an excellent tool for the study of aberrant regeneration following facial nerve injury in the rodent.
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