Lesion of the external branch of the superior laryngeal nerve (EBSLN) - a rare complication after thyroid intervention

Introduction In addition to paralysis of the recurrent laryngeal nerve, lesions of the external branch of the superior laryngeal nerve (EBSLN) may lead to a disturbance of the voice following thyroid intervention. The diagnosis of an EBSLN lesion is not easy and is often overlooked.

Methods On the basis of two patients examined by us, we show the homogeneous data constellation: The medical history, clinical, laryngoscopic and stroboscopic findings and voice assessment are typical of an EBSLN lesion.

Results In our clinic both patients presented after thyroid surgery. Clinical findings include dysphonia with loss of voice pitch and volume and earlier vocal fatigue. Laryngoscopically, a short, thick and flaccid vocal fold appears on the affected side, which seems to be lower in level. In stroboscopy the amplitude is increased. Incomplete glottis closure is seen in one patient as an oval gap, in the other as a posterior triangle chink. The coarse vocal cord mobility was persisted in both patients.

Conclusions With precise knowledge of the injury, medical history, accurate clinical, laryngoscopic and stroboscopic examination as well as the medical history, the diagnosis of an EBSLN lesion is not difficult to detect. The therapy, however, is difficult. Voice therapy can improve the voice's performance, but in many cases with limited satisfaction for the patient. An operative therapy (e.g., cricothyroid approximation) has not been established to date. Preoperative patient information regarding the risk of an EBSLN lesion is therefore important.

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Publication History

Article published online:
10 June 2020