Abstract
IntroductionAnatomical studies on human cadavers have established anastomoses between laryngeal nerves. However, we need to functionally identify motor communication via these anastomoses between the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN) in living bodies. We aim to establish motor interconnections using intraoperative nerve monitoring (IONM).MethodsIONM of 112 EBSLNs and RLNs in 62 thyroidectomy cases was used to establish motor functions of laryngeal nerves. Electrophysiological parameters were recorded, and cricothyroid muscle (CTM) contraction was observed after stimulation of laryngeal nerves.ResultsEighty (71.4%) EBSLNs were visually identified, and 109 (97.3%) EBSLNs were functionally identified with CTM contraction. Stimulation of 74 (67.9%) EBSLNs induced contraction of laryngeal muscles and generated wave amplitude from intrinsic laryngeal musculature. The stimulation of the RLN induced CTM contraction in 65 (58%) of the 112 muscles. The mean conductivity powers of the EBSLN and of the RLN to intrinsic laryngeal musculature were calculated as 231.3 µV and 1354.5 µV, respectively.ConclusionRecordable waveform amplitude with EBSLN stimulation yielded motor relations between laryngeal nerves. CTM contraction after stimulation of the RLN confirmed these relations. These results of IONM established motor interconnections between superior and inferior laryngeal nerves in the majority of patients. The EBSLN may have an effect on motor innervations for intrinsic laryngeal muscles via motor interconnections.
Highlights
Anatomical studies on human cadavers have established anastomoses between laryngeal nerves
The mean conductivity powers of the external branch of the superior laryngeal nerve (EBSLN) and of the recurrent laryngeal nerve (RLN) to intrinsic laryngeal musculature were calculated as 231.3 μV and 1354.5 μV, respectively
- Rates of the functional integrity of the RLN with movements of vocal cords (VC) established by intraoperative nerve monitoring (IONM), and of the EBSLN with observation of the cricothyroid muscle (CTM) twitch
Summary
We need to functionally identify motor communication via these anastomoses between the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN) in living bodies. We aim to establish motor interconnections using intraoperative nerve monitoring (IONM). We aim to determine the roles of the RLN and the EBSLN on the activity of laryngeal musculature using IONM during thyroid surgery
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