LAUSR

cause of UVFI and among these, thyroidectomy is the most common surgery to post the nerve at risk. Other than iatrogenic injury, non-laryngeal malignancies such as lymphoma, esophageal and lung cancer as a group is also among prevalent causes of UVFI. Intubation may result immobility of vocal cord either due to mechanical cause such as in cricoarytenoid joint dislocation or neural injury which leads to vocal fold paresis or paralysis. The pathophysiology of RLN injuries secondary to intubation has been extensively investigated by many authors. In the cadaveric dissection study, the recurrent laryngeal nerve (RLN) is most vulnerable at approximately 6 to 8 mm below the posterior-third of the true vocal fold, whereby the injury can be directly from endotracheal tube (ETT) placement or by the inflated ETT balloon. At this critical anatomical area, the nerve fibers to thyroarytenoid and lateral cricoarytenoid muscles are at most at risk as the course lies above the cricoid cartilage. In comparison to nerve fibers to posterior cricoarytenoid and interarytenoid muscles that lies lateral to cricoid cartilage, they are protected from the inflated cuff pressure. Axonal ischemia is the proposed pathophysiology of the RLN injury. It will results in severe axonal injury if the intubation lasted for more than 6 hours, which subsequently causing nerve conduction failure leading to vocal fold immobility. Although theoretically can happen, bilateral RLN axonal ischemia secondary to both side of pressure exerted from the cuffed ETT balloon, resulting in bilateral vocal fold palsy is a real unfortunate to occur especially in a non-neck setting surgery, which some time may require tracheostomy to open up the airway. We have reported one patient post thyroidectomy having bilateral vocal fold palsy after extubation. The RLNs were functionally intact throughout the continuous neuromonitoring intra-operatively. The condition fully recovered after three-month, with one-week course of oral steroid at the initial part of treatment. We postulated the fatigability of the nerves after repeated stimulation was the underlying cause of the bilateral transient palsy. The left side of vocal fold injury is more common to be reported to be associated with intubation. The postulation is the fact that most clinicians are right handed and thus more tendency to injure the left side of the larynx when introducing the ETT. Second reason is the preference of securing the ETT to right side of the patient‘s mouth which then impose more pressure to the left side of the vocal fold and trachea. The longer course of RLN on left side also imposed a risk for compression injury over the tracheoesophageal groove. This laterality is the same from the surgical point of view whereby the longer course of the left RLN has make it more susceptible to injury from iatrogenic or sequel of a lesion etiologies. RLN palsy commonly presents with hoarseness with variable degree of dysphagia and aspiration symptoms. Regardless of the cause, diminishing of the mucosal sensation and degree of glottal gap carries risk of aspiration with subsequent increase risk of morbidity and mortality from aspiration pneumonia. Each patient is unique as the capability of re-innervation of the larynx is different among individuals. However, it is suggested that any patient who is suspected to have a new onset UVFI is referred to an otorhinolaryngologist for further assessment of the larynx and for immediate intervention of UVFI to reduce the morbidity and mortality mentioned above.