Difficult laryngoscopy and cephalometric roentgenograms in obstructive sleep apnea syndrome patients undergoing...

We retrospectively studied the incidence of difficult laryngoscopy in 53 subjects with obstructive sleep apnea syndrome (OSAS) undergoing uvulopalatopharyngoplasty (UPPP) and 72 subjects with chronic otitis media undergoing tympanoplasty (control group). The incidence of difficult laryngoscopy in the UPPP group was significantly higher than in the control group (18.9%vs 4.2%,P<0.001). To analyze the anatomical findings of difficult laryngoscopy in UPPP patients, cephalometric roentgenograms were compared between patients in whom direct laryngoscopy was difficult (difficult patients,n=10) and patients in whom direct laryngoscopy was not difficult (nondifficult patients,n=43). Cephalometric atlanto-occipital distance (cAOD) was less than 4mm in 80% of the difficult patients, and there were significant differences between the difficult patients and the nondifficult patients (2.8±3.3 mmvs 6.7±3.0 mm, mean ±SD,P<0.001). There were significant differences in cephalometric effective mandibular length/cephalometric posterior depth of mandible ratio (cEML/cPDM) between the difficult patients and the nondifficult patients (4.0±0.6vs 4.5 ±0.8,P<0.01); however, the calculation of cEML/cPDM was more difficult than cAOD. We concluded that OSAS patients undergoing UPPP are at high risk for difficult laryngoscopy, and that cAOD calculated from cephalometric roentgenograms is an easy and sensitive predictive indicator for the estimation of difficult laryngoscopy.