New Experimental Model of Facial Nerve Function and Integrity to Evaluate Regeneration

Abstract

Objectives:

The ideal animal model for nerve regeneration studies is an object of controversy because all models described by the literature have advantages and disadvantages. Small animals such as rats have been repeatedly used in experimental procedures because of their easy caretaking and handling, resistance to manipulation and infections, and low cost. In this case, rats have the additional benefit of tolerating bilateral facial paralysis. This study aimed to describe the histologic and functional (electroneuromyographic) patterns of the mandibular branch of the facial nerve of Wistar rats in order to create a new experimental model of facial nerve regeneration.

Methods:

Forty-two male Wistar rats were submitted to neurophysiologic evaluation by a nerve conduction test of the mandibular branch of the facial nerve to obtain the compound muscle action potential. Twelve of these rats had the mandibular branch of the facial nerve surgically removed and submitted to histologic analysis (total axon number, partial axonal density, and axonal diameter) of the proximal and distal nerve segments.

Results:

There was no statistical difference in the functional and histologic variables studied.

Conclusion:

These new histologic and functional standards of the mandibular branch of the facial nerve of rats establish an objective, easy, and greatly reproducible model for future facial nerve regeneration studies.