Introduction Rodent whisking behavior is supported by the buccal and mandibular branches of the facial nerve, a description of how these branches converge and contribute to whisker movement is lacking. Methods Eight rats underwent isolated transection of either the buccal or mandibular branch and subsequent opposite branch transection. Whisking function was analyzed following both transections. Anatomical measurements, and video recording of stimulation to individual branches, were taken from both facial nerves in 10 rats. Results Normal to near-normal whisking was demonstrated after isolated branch transection. Following transection of both branches whisking was eliminated. The buccal and mandibular branches form a convergence just proximal to the whisker-pad, named the “distal pes.” Distal to this convergence, we identified consistent anatomy that demonstrated cross-innervation. Conclusion The overlap of efferent supply to the whisker pad must be considered when studying facial nerve regeneration in the rat facial nerve model.

Objective To evaluate whether a series of pharmacologic agents with potential neuroprotective effects accelerate and/or improve facial function recovery after facial nerve crush injury. Study Design Randomized animal study Methods Eighty female Wistar-Hannover rats underwent head fix implantation and daily conditioning. Animals then underwent standardized crush injury to the main trunk of the facial nerve, and were randomized to receive treatment with Atorvastatin (n=10), Sildenafil (n=10), Darbepoetin (n=20), or corresponding control agent (n=40). The return of whisking function was tracked throughout the recovery period. Results Darbepoetin treatment showed improved whisking amplitude on postoperative days 15, 18, 21, and at week 5. Additionally, Darbepoetin treated animals had higher whisking velocity and acceleration on postoperative days 18, 21, and week 5. Sildenafil treatment showed improved whisking velocity over controls on postoperative day 12, and improved whisking acceleration on postoperative day 12 and 13 compared with controls, however this marginal benefit was not seen on the subsequent postoperative days. Atorvastatin treatment had no effect on facial function recovery after facial nerve crush injury, compared with controls. By week eight, the Darbepoetin and control treated animals had achieved complete recovery. Conclusion Amongst the several potentially neuroprotecitve agents evaluated, only Darbepoetin administration resulted in accelerated facial function recovery after facial nerve crush injury. Further efforts to define the mechanism of action and translate these findings to the use of Darbepoetin in the care of patients with traumatic facial paralysis are needed.

Management of facial paralysis is often times overlooked when defining a care plan for NF2 patients who typically have multiple brain and spine tumors. The paralyzed smile may be treated successfully with single-stage free gracilis muscle transfer in the motivated patient.