After orthognathic surgery or mandibular fracture repair, intermaxillary fixation is often required. Vocal cord palsy is a rare complication following general anaesthesia with tracheal intubation and the incidence is around 0.1%.1 The onset of vocal cord palsy is usually noticed by postoperative hoarseness after emergence from general anaesthesia. However, the detection of postoperative vocal cord palsy may go undetected in patients after intermaxillary fixation, because these patients cannot speak as usual. We have experienced several cases where recognition of postoperative vocal cord palsy was delayed because of intermaxillary fixation. The postoperative vocal cord palsy was noticed only after the intermaxillary fixation was removed some weeks after surgery. One of the causes of vocal cord paralysis is arytenoid cartilage dislocation and delayed diagnosis will prevent the urgent correction required to prevent long-term damage. The gold standard of assessment of vocal cord mobility is laryngoscopy. However, the examination may lead to gagging and retching and induce significant stress or discomfort.
Recently, ultrasonography has been used to evaluate patients’ airways,2 and transcutaneous vocal cord ultrasonography has been used to diagnose vocal cord palsy.2–4 Vats et al.4 reported that examination using transcutaneous vocal cord ultrasonography correlated with laryngoscopy in 81.2% of cases, hence it may be able to substitute for laryngoscopy as a means of assessing vocal cord movement. We began using this technique on patients with intermaxillary fixation after oral and maxillofacial surgery in order to prevent delay in the recognition of postoperative vocal cord palsy.
Transcutaneous vocal cord ultrasonography was performed as in previous reports.5 A linear array ultrasound transducer was placed transversely on the cricothyroid ligament and sliding the transducer toward the head allows visualisation of the vocal cord and laryngeal structures (Fig. 1). The operator instructs the patient to vocalise while the transducer is kept at the proper location and vocal cord movement can be observed during phonation (Fig. 2). Although vocal cord movement after patients with intermaxillary fixation may be small when compared to normal patients, imbalance in the observed movement is enough to diagnose postoperative vocal cord palsy. Since swallowing complicates scanning the vocal cords and laryngeal structures patients are asked to avoid swallowing during the assessment.
Delay in the recognition of postoperative vocal cord palsy often makes its treatment difficult. Transcutaneous vocal cord ultrasonography is a non-invasive, convenient, low-cost and reliable method to assess vocal cord movement. We believe that transcutaneous vocal cord ultrasonography is useful as an early diagnostic method to identify postoperative vocal cord palsy in patients with intermaxillary fixation after oral and maxillofacial surgery. It may make prompt treatment of postoperative vocal cord palsy possible.
Acknowledgements relating to this article
Assistance with the study: we thank Professor Paul Moore (University of Pittsburgh) and Shoko Gamoh (Osaka Dental University) for improving this manuscript.
Financial support and sponsorship: none.
Conflicts of interest: none.
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