Nerve Fibers in Laryngeal Muscle Following Injury on Nerve

Abstract

Objective: Compare the modulation of nerve fibers, 1) between recurrent laryngeal nerve (RLN) and vagus nerve (VN) in the thryroarytenoid (TA) muscle, 2) between RLN in TA and peroneal nerve (PN) in tibialis anterior (TbA) muscle following nerve section and immediate anastomosis using rat model.

Method: Rats were sacrificed at 5 occasions after nerve section followed by anastomosis. Axons, myelin sheaths, Schwann cells, nerve terminals, and acetylcholine receptors in TA and TbA were quantified by immunohistochemistry. Data were expressed as the ratio between treated and untreated sides (T/U ratio).

Results: Eighteen weeks posttreatment, the mean T/U ratios for axon expression were RLN: 68.5%, VN: 0.0% and PN: 99.2%; the ratios for myelin sheath were RLN: 0.0%, VN: 0.0%, PN: 97.6%; the ratios for Schwann cells were RLN: 53.7%, VN: 0.0%, and PN: 93.6%; the ratios for nerve terminals were RLN: 61.0%, VN: 0.0%, and PN:96.4%; and the ratios for acetylcholine receptors were almost 100% for RLN and PN and 67.2% for VN. For all measurements there was a significant difference between RLN and PN at the 18 weeks time point (P < .001).

Conclusion: These results show that, at 18 weeks, regeneration did not occur in VN. On the other hand, regeneration occurred in both RLN and PN, moreover, nerve fibers were more matured in PN compared to RLN.