Injury of the external branch of the superior laryngeal nerve in thyroid surgery

Abstract

Injury of the external branch of the superior laryngeal nerve is one of the complications in thyroid surgery, the frequency of which varies within very wide limits due to the difficulties in diagnosis. The complaints relate to a change in voice tone, which significantly impairs the quality of life of patients, especially those with voice profession. The most accurate specific method for diagnosis is electroneuromyography but this technique is very difficult to perform and not used in routine practice. To diagnose the lesion of the external branch of superior laryngeal nerve the authors used laryngoscopy, laryngostroboscopy and spectral analysis of the voice, which revealed the frequency of nerve injury and dynamic monitoring of voice recovery in the patient.
 Objective — to examine the frequency of lesions of the external branch of superior laryngeal nerve in thyroid surgery on the basis of changes in the laryngoscopic picture, spectral analysis of the voice and dynamic monitoring of their recovery during treatment
 Materials and methods. The study was conducted in the surgical department of the Ukrainian Scientific and Practical Center for Endocrine Surgery, Transplantation of Endocrine Organs and Tissues MOH of Ukraine with involvement of 241 operated patients. Examination of the larynx and voice examination were performed before surgery, on the 2 — 3 days and 6 and 12 months after surgery. Diagnosis was performed using methods: videolaryngoscopy, videolaryngostroboscopy, spectral analysis of the voice.
 Results. Clinical signs of trauma to the external branch of the superior laryngeal nerve were found in 8 (3.3 %) patients out of 241 operated. Patients received a course of phonopedia and stimulation therapy in the absence of contraindications. Voice recovery over time was recorded in 7 (87.5 %) patients, no voice recovery in 1 (0.4 %).
 Conclusions. Injury of the external branch of superior laryngeal nerve after surgery on the thyroid gland is a complication after thyroid surgery which does not happen often (3.3 %). This complication is very difficult to detect, considering inconspicuous symptoms, the lack of specificity of the laryngoscopic picture and the peculiarities of diagnostic methods. It is not always possible to fully restore the voice when the external branch of the superior laryngeal nerve is damaged (permanent injury accounts for 0.4 % of the total number of operations on the thyroid gland and 85.0 % of the total number of patients with damage to the external branch of the superior laryngeal nerve), which requires dynamic monitoring of patients and timely treatment administration.