Objectives

To demonstrate the normative vagal and recurrent laryngeal nerve (RLN) electromyographic parameters during intraoperative nerve monitoring and to investigate the e ect of age and gender on the electromyographic parameters of vagal and RLN.

Methods

Seventy-nine consecutive patients with 151 nerves at risk were included. All patients underwent preoperative and postoperative vocal cord examination. Any patient with abnormal ndings on preoperative vocal cord examination was excluded. Intraoperative nerve monitoring (IONM) was applied by a standardized IONM set up using the noninvasive surface electrode endotracheal tube and the Dr. Langer Avalanche SI NIM monitor with a hand hold stimulating probe. e amplitude and the latency of the evoked response for vagal and RLN were recorded initially at the beginning of surgery.

Results

e mean amplitude and latency on the le versus right RLN, and the mean amplitude on le versus right vagal nerve showed no signi cant di erence. e latency was signi cantly longer on the le (5.8±1.2 ms) versus right vagal nerve (4.2±0.9 ms)(P=0.0001). e mean amplitude was signi cantly higher on le RLN (896±515μV) compared to le vagal nerve (618±372μV). e le vagus mean latency was longer compared to le RLN (5.8±1.2 vs 2.1±1ms; P=0.0001). e mean amplitude of right RLN and right vagal nerve was similar (P=0.7). e right vagus mean latency was signi cantly longer compared to right RLN (4.2±0.9ms vs 2.1±0.6ms P=0.0001).Gender had no signi cant e ect on latency and amplitude measurements. Age had no signi cant correlation with latency of RLN and vagal nerve. e amplitude was signi cantly lower on RLN and vagal nerve in patients with an age above 60 years compared to younger patients (for RLN: 653±271μVvs. 845±526μV; P=0.01)(for vagal nerve:490±206μV vs. 692±458μV; P=0.001).

Conclusions

Gender had no signi cant e ect on the latency and amplitude measurements. e amplitude on RLN and vagal nerve was signi cantly lower in older patients (age above 60 years) compared to younger patients.