Post-thyroidectomy vocal cords paralysis despiste normal intraoperative neuromonitoring of the laryngeal nerves during surgery.

Background: 
Recurrent laryngeal nerve (RLN) injury is one of the most common complications of thyroid surgery. RLN injury can cause vocal cord paralysis, affecting the patient’s voice and the quality of life. Injury of the external branch of the superior laryngeal nerve can cause cricothyroid muscle denervation affecting high vocal tones. Thus, securing the laryngeal nerves in these surgeries is of utmost importance. Thats why nowadays, the use of intraoperative neuromonitoring with the NIM tube during surgery is very extended.
Case report
71 years old female with multinodular goitre diagnosed 8 months ago. Surgeons decided to perform total thyroidectomy because it's big size. The intubation was performed with glidescope, looking at the perfect colocation of the NIM tube. After the nerve stimulation was checked, the tube was fixed. During surgery no injury of the recurrent laryngeal nerves was observed. She was extubated in the operation room successfully, and traslated to the postoperatory ICU.
The day after, She sarted with progressive dysphagia. At first She was treated with corthicoids and antihistamines, because no hematoma or edema was observed and she was already taking these medications at home, but the clinical condition get worst hours later and she presented dysphonia. At this moment, we called the otolaryngologist, who performed a nasal fibrobroncoscopy and diagnosed a "bilateral paresia of vocal cords with important reduction of the air flow, but conserved".
Presuming the inflamatory origen of the paralysis, due the intraoperative monitoring of the RLN and the clinical timing, we decided to amplify medical treatment and we added adrenaline nebulizations.
The patient remained stable, and the symptoms slowly disapeared (2-3 days). However, a tracheostomy had to be performed 7 days after the thyroidectomy because the improvement was too slow to alow minimal efforts.
Discussion and Learning points
The vocal cords paralysis is an important postoperative complication and it has to be avoided if possible (with a narrow intraoperative monitoring and Intraoperative visual identification of both RLN ) and quickly diagnosed if it happens. The treatment will depend on the symptons and the clinical situation of the patient. We can not forget that even with a correct intraoperative monitoring of the RLN, the vocal cord paralysis may occur. 
References
Deniwar A, Kandil E, Randolph G. Electrophysiological neural monitoring of the laryngeal nerves in thyroid surgery: review of the current literature. Gland Surg 2015;4(5):368-375. doi: 10.3978/j.issn.2227-684X.2015.04.04