Is laryngeal mask airway-related vocal chord palsy always laryngeal mask airway-related?

Abstract

Editor—Voice problems after general anaesthesia can either be caused by vocal chord trauma, by dislocation of the arytenoid cartilages, or by recurrent laryngeal nerve palsy. Both tracheal intubation1Kikura M Suzuki K Itagaki T Takada T Sato S Age and comorbidity as risk factors for vocal cord paralysis associated with tracheal intubation.Br J Anaesth. 2007; 98: 524-530Abstract Full Text Full Text PDF PubMed Scopus (67) Google Scholar and laryngeal mask airway (LMA †LMA® is the property of Intavent Limited. †LMA® is the property of Intavent Limited.) are a possible cause for recurrent laryngeal nerve palsy. As depicted in Figure 1, the cuff of an LMA is situated dorsocranial of the cricothyroidal joint where the recurrent laryngeal nerve enters the larynx. We consider direct pressure of the cuff to the nerve at this location to be the most probable pathomechanism of LMA-induced recurrent laryngeal nerve palsy. Currently, there are 14 published cases of patients who developed recurrent laryngeal nerve palsy.2Endo K Okabe Y Maruyama Y Tsukatani T Furukama M Bilateral vocal cord paralysis caused by laryngeal mask airway.Am J Otolaryngol. 2007; 28: 126-129Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar In our voice clinic, we have treated a 74-yr-old male patient who developed palsy of his left recurrent laryngeal nerve after anaesthesia for foot surgery where an LMA was used (normal vocalization before operation). Computed tomography showed no pathology at the skull base or in the mediastinum. At first glance, this case may appear to be the 15th case with LMA-induced vocal chord palsy. However, computed tomography revealed diffuse idiopathic skeletal hyperostosis of the cervical spine. Closer examination showed a large osteophyte just next to the rim between trachea and oesophagus where the recurrent laryngeal nerve is situated. Depending on head and neck positioning during anaesthesia, it is possible that the osteophyte compressed the nerve and thus caused the palsy.3Aydin K Ulug T Simsek T Bilateral vocal cord paralysis caused by cervical spinal osteophytes.Br J Radiol. 2002; 75: 990-993Crossref PubMed Scopus (16) Google Scholar 4Yoskovitch A Kantor S Cervical osteophytes presenting as unilateral vocal fold paralysis and dysphagia.J Laryngol Otol. 2001; 115: 422-424Crossref PubMed Scopus (21) Google Scholar Therefore, it is not clear whether the recurrent laryngeal nerve palsy in our patient was caused by LMA or by the cervical spine osteophyte. There are a number of possible causes of unilateral palsy of the recurrent laryngeal nerve. Therefore, whenever this occurs after LMA use, a thorough search for other possible causes is needed before assigning the palsy as LMA-induced. Further case reports of LMA-induced vocal chord palsy should report evidence against other causes of vocal chord palsies.