Is laryngeal mask airway-related vocal chord palsy always laryngeal mask airway-related?
Aachen, Germany
* E-mail: blehnert{at}ukaachen.de
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 intubation1 and laryngeal mask airway (LMA
) 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.
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Currently, there are 14 published cases of patients who developed recurrent laryngeal nerve palsy.2 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.3 4 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.
Footnotes
LMA® is the property of Intavent Limited. 
References
1 Kikura 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) 98:524–30.
2 Endo K, Okabe Y, Maruyama Y, Tsukatani T, Furukama M. Bilateral vocal cord paralysis caused by laryngeal mask airway. Am J Otolaryngol (2007) 28:126–9.[CrossRef][Web of Science][Medline]
3 Aydin K, Ulug T, Simsek T. Bilateral vocal cord paralysis caused by cervical spinal osteophytes. Br J Radiol (2002) 75:990–3.
4 Yoskovitch A, Kantor S. Cervical osteophytes presenting as unilateral vocal fold paralysis and dysphagia. J Laryngol Otol (2001) 115:422–4.[Web of Science][Medline]
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