Voice dysfunction following thyroidectomy
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Background: Voice dysftmction after thyroid surgery is not rare, and is generally reported in terms of recurrent laryngeal nerve (RLN) or superior laryngeal nerve (SLN) injuries. However, voice dysftmction is more complex than simply nerve integrity. Prompt recognition of causes of dysphonia is essential so that relevant therapeutic decision allows early management. Objective: The aim of the present work is to analyze voice change after thyroidectomy for patients with normal pre-operative voice. Methodology: The study included 30 patients who had developed voice changes within 6 months after thyroidectomy. They were subjected to indirect laryngoscopy (to examine the vocal folds position, mobility and pathological lesions), videostroboscopy (to measure vibration, periodicity, amplitude, symmetry, glottic closure and mucosal wave of the vocal folds) and electromyelography (EMG) (to differentiate between neurogenic and mechanical limitation of the vocal folds mobility). Results: It was found that dysphonia after thyroid surgery was caused by neurogenic causes (RLN and SLN injuries) in 23 patients (76.7%), non-neurogenic causes in 5 patients (16.7%) and combined causes in 2 patients (6.6%). EMG studies revealed complete denervation in 6 patients (20%) and incomplete denervation (paresis) in 19 patients (63.3%). In conclusion, post-thyroidectomy dysphonias are not rare. Injuries of the RLN constitute the main cause. Non-neurogenic (traumatic) injury is another contributing factor. Diagnosis is essential for early management through videostroboscopy and EMG which is specific to differentiate between neurogenic and traumatic injuries and to detect complete or incomplete denervation.