Laryngeal dysfunction after thyroid surgery: diagnosis, evaluation and treatment

Because of the close anatomical relationships between thyroid gland and laryngeal nerves, sensory-motor impairment of the laryngeal functions is a well known possible complication of thyroid surgery. Laryngeal nerve paralysis can present with various and often associated symptoms like dysphagia, aspiration, voice alteration or dyspnea. Several examination procedures are mandatory to perform a complete neuro-laryngeal evaluation: rigid and flexible video-stroboscopy will assess the abductor, adductor and tensor functions in breathing, sniffing, talking and eventually singing tasks. Laryngeal electromyography (LEMG), despite its technical difficulties, brings valuable objective and pronostic informations. Aerodynamic assessment of voice production and objective acoustic voice evaluation are important for patients' follow-up, especially for voice professionals like teachers and singers. Treatment of laryngeal sensory-motor nerve paralysis can be conservative, with the help of speech therapy. Early surgical treatment is indicated in cases with severe functional problems like aspiration pneumonia, disabling breathy hypophonia, ineffective cough, disabling dyspnea. Surgical therapy at 6 to 9 months after injury is indicated in patients who demonstrate evidence of denervation or little activity on LEMG and have a poor response to a reasonable trial of speech therapy. Many surgical procedures are available. Depending on the type of neuro-laryngeal deficit, the main and more widely used techniques are: injection laryngoplasty, medialization thyroplasty, arytenoid adduction, arytenoidopexy, crico-thyroid approximation, endoscopic laser cordotomy and re-innervation procedures.