Lateral neck radiography in prediction of difficult laryngoscopy in Chinese patients

Several tests of radiology have been designed to predict difficult laryngoscopy, but there were few relative studies of Chinese patients. Our study is to investigate the accuracy of lateral neck radiography in predicting difficult laryngoscopy in Chinese patients. The operative database of Xuanwu Hospital, Capital Medical University, was reviewed and all the patients who had performed lateral neck radiography before thyroid surgery from February 2014 to February 2015 were recruited. The results of Modified Mallampati test (MMT) and Thyromental distance (TMD) of the patients were obtained from the Database. Two trained reviewers independently measured α’ (the angle between hyoid cartilage, root of epiglottis and arytenoid cartilage) and several other angles and parameters on the X-ray. Receiver operating characteristic curves (ROC) were drawn and the areas under curves (AUC) were calculated to analyze the accuracy of each indicator. The cut off points were determined by maximizing the Youden index. In the study, 114 patients were included. The most accurate indicator of lateral neck radiography was α’, of which AUC was 0.896 (95% confidence interval [0.813, 0.979]). The cut off point of α’ was set as 85.52. The clinical test MMT (47% and 75%) has lower sensitivity and specificity than α’ (87% and 86%) and other indicators have lateral neck radiography. The diagnostic accuracy of lateral neck radiography in prediction of difficult laryngoscopy in Chinese patients may be superior to MMT and TMD. However, the method of lateral neck radiography is not perfectly precise.