Long-Term Functional Recovery after Facial Nerve Transection and Repair in the Rat

Abstract

Background The rodent model is commonly used to study facial nerve injury. Because of the exceptional regenerative capacity of the rodent facial nerve, it is essential to consider the timing when studying facial nerve regeneration and functional recovery. Short-term functional recovery data following transection and repair of the facial nerve has been documented by our laboratory. However, because of the limitations of the head fixation device, there is a lack of long-term data following facial nerve injury. The objective of this study was to elucidate the long-term time course and functional deficit following facial nerve transection and repair in a rodent model.

Methods Adult rats were divided into group 1 (controls) and group 2 (experimental). Group 1 animals underwent head fixation, followed by a facial nerve injury, and functional testing was performed from day 7 to day 70. Group 2 animals underwent facial nerve injury, followed by delayed head fixation, and then underwent functional testing from months 6 to 8.

Results There was no statistical difference between the average whisking amplitudes in group 1 and group 2 animals.

Conclusion Functional whisking recovery 6 months after facial nerve injury is comparable to recovery within 1 to 4 months of transection and repair, thus the ideal window for evaluating facial nerve recovery falls within the 4 months after injury.

Keywords

facial nerve transection and repair - facial paralysis - regeneration - whisking

• References

• 1 Ryzenman JM, Pensak ML, Tew Jr JM. Facial paralysis and surgical rehabilitation: a quality of life analysis in a cohort of 1,595 patients after acoustic neuroma surgery. Otol Neurotol 2005; 26 (3) 516-521 , discussion 521
• 2 Lee J, Fung K, Lownie SP, Parnes LS. Assessing impairment and disability of facial paralysis in patients with vestibular schwannoma. Arch Otolaryngol Head Neck Surg 2007; 133 (1) 56-60
• 3 Coulson SE, O'dwyer NJ, Adams RD, Croxson GR. Expression of emotion and quality of life after facial nerve paralysis. Otol Neurotol 2004; 25 (6) 1014-1019
• 4 Ishii L, Godoy A, Encarnacion CO, Byrne PJ, Boahene KD, Ishii M. Not just another face in the crowd: society's perceptions of facial paralysis. Laryngoscope 2012; 122 (3) 533-538
• 5 Kumagami H. Experimental facial nerve paralysis. Arch Otolaryngol 1972; 95 (4) 305-312
• 6 Burgette RC, Benscoter BJ, Monaco GN , et al. A rat model for intracranial facial nerve crush injuries. Otolaryngol Head Neck Surg 2012; 146 (2) 326-330
• 7 Kim J, Han SJ, Shin DH, Lee WS, Choi JY. Subthreshold continuous electrical stimulation facilitates functional recovery of facial nerve after crush injury in rabbit. Muscle Nerve 2011; 43 (2) 251-258
• 8 Zhang W, Sun B, Yu Z, An J, Liu Q, Ren T. High dose erythropoietin promotes functional recovery of rats following facial nerve crush. J Clin Neurosci 2009; 16 (4) 554-556
• 9 Brenner MJ, Moradzadeh A, Myckatyn TM , et al. Role of timing in assessment of nerve regeneration. Microsurgery 2008; 28 (4) 265-272
• 10 Moran LB, Graeber MB. The facial nerve axotomy model. Brain Res Brain Res Rev 2004; 44 (2-3) 154-178
• 11 Hadlock TA, Heaton J, Cheney M, Mackinnon SE. Functional recovery after facial and sciatic nerve crush injury in the rat. Arch Facial Plast Surg 2005; 7 (1) 17-20
• 12 Heaton JT, Kowaleski JM, Bermejo R, Zeigler HP, Ahlgren DJ, Hadlock TA. A system for studying facial nerve function in rats through simultaneous bilateral monitoring of eyelid and whisker movements. J Neurosci Methods 2008; 171 (2) 197-206
• 13 Hadlock T, Kowaleski J, Lo D , et al. Functional assessments of the rodent facial nerve: a synkinesis model. Laryngoscope 2008; 118 (10) 1744-1749
• 14 Hadlock TA, Kowaleski J, Lo D, Mackinnon SE, Heaton JT. Rodent facial nerve recovery after selected lesions and repair techniques. Plast Reconstr Surg 2010; 125 (1) 99-109
• 15 Hadlock T, Kowaleski J, Mackinnon S, Heaton JT. A novel method of head fixation for the study of rodent facial function. Exp Neurol 2007; 205 (1) 279-282
• 16 Lindsay RW, Heaton JT, Edwards C, Smitson C, Vakharia K, Hadlock TA. Daily facial stimulation to improve recovery after facial nerve repair in rats. Arch Facial Plast Surg 2010; 12 (3) 180-185
• 17 Bermejo R, Szwed M, Friedman W, Ahissar E, Zeigler HP. One whisker whisking: unit recording during conditioned whisking in rats. Somatosens Mot Res 2004; 21 (3-4) 183-187
• 18 Angelov DN, Ceynowa M, Guntinas-Lichius O , et al. Mechanical stimulation of paralyzed vibrissal muscles following facial nerve injury in adult rat promotes full recovery of whisking. Neurobiol Dis 2007; 26 (1) 229-242
• 19 Skouras E, Merkel D, Grosheva M , et al. Manual stimulation, but not acute electrical stimulation prior to reconstructive surgery, improves functional recovery after facial nerve injury in rats. Restor Neurol Neurosci 2009; 27 (3) 237-251
• 20 Wood MD, Kemp SW, Weber C, Borschel GH, Gordon T. Outcome measures of peripheral nerve regeneration. Ann Anat 2011; 193 (4) 321-333
• 21 Fu SY, Gordon T. The cellular and molecular basis of peripheral nerve regeneration. Mol Neurobiol 1997; 14 (1-2) 67-116
• 22 Witzel C, Rohde C, Brushart TM. Pathway sampling by regenerating peripheral axons. J Comp Neurol 2005; 485 (3) 183-190
• 23 Brushart TM, Hoffman PN, Royall RM, Murinson BB, Witzel C, Gordon T. Electrical stimulation promotes motoneuron regeneration without increasing its speed or conditioning the neuron. J Neurosci 2002; 22 (15) 6631-6638
• 24 Sunderland S. Rate of regeneration in human peripheral nerves; analysis of the interval between injury and onset of recovery. Arch Neurol Psychiatry 1947; 58 (3) 251-295
• 25 Mackinnon SE, Dellon AL, O'Brien JP. Changes in nerve fiber numbers distal to a nerve repair in the rat sciatic nerve model. Muscle Nerve 1991; 14 (11) 1116-1122
• 26 Hare GM, Evans PJ, Mackinnon SE , et al. Walking track analysis: a long-term assessment of peripheral nerve recovery. Plast Reconstr Surg 1992; 89 (2) 251-258
• 27 Guntinas-Lichius O, Irintchev A, Streppel M , et al. Factors limiting motor recovery after facial nerve transection in the rat: combined structural and functional analyses. Eur J Neurosci 2005; 21 (2) 391-402
• 28 Fox IK, Brenner MJ, Johnson PJ, Hunter DA, Mackinnon SE. Axonal regeneration and motor neuron survival after microsurgical nerve reconstruction. Microsurgery 2012; 32 (7) 552-562