Induced Vagal and Recurrent Laryngeal Nerve Trauma in Canines

Abstract

Objective: 1) Identify electromyographic changes (EMG), specifically amplitude and latency changes that are associated with nerve injury. 2) Correlate induced recurrent laryngeal nerve (RLN) and vagal nerve trauma in dogs with postoperative vocal cord function.

Method: The study was conducted over a 2-year period. The vagus and recurrent laryngeal nerve electrophysiological parameters of 12 canines were recorded during induced nerve injury. These electrophysiological parameters were correlated with postoperative vocal cord function.

Results: Twelve canines were subjected to vagus and/or RLN trauma. Compression and/or stretch trauma was associated with significant posttrauma electromyographic parameter changes. An amplitude decrease of greater than 80% and latency increase of greater than 10% was observed in the vocal cord palsy group. In addition, aggressive nerve stimulation caused mild amplitude variation but no associated vocal cord palsy. Prolonged nerve stimulation caused significant EMG changes, which recovered, but no associated vocal cord palsy.

Conclusion: We present canine vagal and RLN electrophysiological data. Preliminary data suggest that electrophysiological parameter changes are associated with vocal cord palsy. Prolonged nerve stimulation is safe. Human vagal nerve and RLN studies are required to assess if similar EMG changes are seen in humans and associated with vocal cord palsy.