The proximal loop was reported to be between the ebSLN and ibSLN, whereas the distal loop was reported to be between the ebSLN and the recurrent laryngeal nerve.
The nerve extended between the ebSLN and the ibSLN in all cases.
The laryngeal skeleton deserves important consideration in the setting of negative voice outcomes after thyroidectomy in the absence of RLN and EBSLN injury.
Although none of the patients demonstrated RLN injury and only one had EBSLN injury, 30% reported subjective voice changes one week postoperatively and 14% reported voice changes at 3 months.
highlights this principle by demonstrating that 23.8% of patients with EBSLN injury and vocal incompetence eventually developed muscle tension dysphonia in their compensatory effort to generate a stronger voice.
EBSLN is also at risk of inadvertent injury during thyroidectomy, although clinical trials have shown a low injury rate .
Control LNM group P group Initial visual ID of 179/185 152/156 (974%) 0.76 (a) RLN (%) (96.8%) Final ID of RLN (%) 179/185 156/156 (100%) 0.03 (a) (96.8%) P -- 0.12 (a) -- Initial visual ID of 73/185 67/156 (42.9%) 0.51 EBSLN (%) (39.5%) Final ID of EBSLN 73/185 118/156 (75.6%) <0.01 (%) (39.5%) P -- <0.01 -- ID: identification; NAR: nerve at risk; LNM: laryngeal nerve monitoring; RLN: recurrent laryngeal nerve; EBSLN: external branch of the superior laryngeal nerve.
Nerve monitoring facilitates careful nerve dissection and localization, and it can be applied to both the RLN and EBSLN. The monitoring does not change the operative technique.
The position of the EBSLN is variable, and the nerve is not always located and identified during surgery.
Only 1 patient exhibited obvious laryngoscopic evidence of EBSLN dysfunction, but EMG was not performed in this study.
The anatomic course of the EBSLN can be variable, and it may be altered by the size and pathology of the thyroid.
RLN and EBSLN location and preservation techniques include intraoperative electrophysiologic monitoring by surface or needle electrodes, direct observation of the vocal folds via fiberoptic or direct laryngoscopy, and recording muscle contraction and nerve integrity with a nerve monitor.