New insights into the mechanism of injury to the recurrent laryngeal nerve associated with the laryngeal mask airway.

With the popular use of the laryngeal mask airway (LMA), recurrent laryngeal nerve injury associated with the LMA, which might cause serious complications, has recently been reported. The true mechanism, however, remains unclear, which makes effective prevention and treatment of this disorder difficult. On the basis of the anatomical relationship of the laryngopharynx and the laryngeal mask and the progressive recovery in most reported cases, we hypothesize that demyelinating neuropraxia resulting from direct mechanical compression contributes to the recurrent nerve injury associated with the LMA. A series of clinical cases which showed that recurrent nerve palsy may occur as a result of cuff over-inflation and/or prolonged LMA insertion period support the hypothesis. Several animal studies also reveal that high laryngeal mask airway intra-cuff pressure might cause laryngopharyngeal mucosa damage, but there is no experimental research about LMA-related recurrent nerve injury. Therefore, further investigation by establishing an animal model might disclose the definite mechanism of the injury and evaluate the process of nerve recovery. The potential implications arising from this testable hypothesis might be helpful in developing clinical therapeutic approaches for this complication.