Radiologic indicators for prediction of difficult laryngoscopy in patients with cervical spondylosis

BACKGROUND We identified the most useful variables for prediction of difficult laryngoscopy in patients with cervical spondylosis according to physical indicators and preoperative skeletal X-ray and soft tissue MRI measurements. We hypothesized that there was a closer association between difficult laryngoscopy and radiologic indicators. METHODS We randomly enroled 315 patients undergoing elective cervical spine surgery and analysed the radiological and physical data in predicting difficult laryngoscopy. RESULTS We identified five variables that were most useful in predicting difficult laryngoscopy: the inter-incisor gap (P = 0.006), modified Mallampati test score (P = 0.004), distance from the highest point of the hyoid bone to the mandibular body (P < 0.001), most antero-inferior point of the upper central incisor tooth (P < 0.001), and length of the epiglottis (P = 0.002). Binary multivariate logistic regression analyses identified three factors that were independently associated with difficult laryngoscopy: the Mallampati score, distance from the hyoid bone to the mandibular body, and the anterior-inferior point of the upper central incisor tooth. The odds ratios and 95% confidence intervals were 1.547 (1.029-2.327), 1.222 (1.139-1.310), and 1.224 (1.133-1.322), respectively. The AUC for hyoid bone distance to mandibular body (0.832) was larger than that of anterior-inferior point of the upper central incisor tooth (0.802, P > 0.05) and that of modified Mallampati test (0.602, P < 0.05). CONCLUSION Distance from the highest point of the hyoid bone to the mandibular body appears to be the most accurate indicator for difficult laryngoscopy in patients with cervical spondylosis.