Physical and Radiological Parameters to Predict Difficult Laryngeal Exposure in Patients Undergoing microlaryngeal Surgery

Lee, Yong Won; Roh, Jong Lyel

Abstract

BACKGROUND AND OBJECTIVES
Although difficult laryngeal exposure (DLE) is a common problem encountered during rigid laryngoscopy, no anticipatory parameters have been formally noted as its reliable predictors. The purpose of this study is to identify physical and radiologic parameters to predict DLE according to a new classification of laryngeal exposure (LE score) suggested by authors. STUDY DESIGN: Fifty-eight patients underwent larygomicrosurgery were given LE score from grade 1 to 4 according to the glottic visualization on suspension laryngoscopy using a anterior commissure laryngoscope. Several parameters to predict DLE were investigated to compare DLE cases with control. SUBJECTS AND METHOD: All patients received physical and radiological examinations that encompassed the following sixteen measurements: sex, age, modified Mallampati index (MMI), body mass index (BMI), neck circumference, anterior mandibular height (AMH), hyoid-mental distance (HMD), thyroid-mental distance (TMD), horizontal thyroid-mental distance (HTD), vertical thyroid-mental distance (VTD), sternummental distance (SMD), vertical incisor-thyroid distance (VITD), horizontal incisor-thyroid distance (HITD), thyroid incisor angle (TIA), thyroid-mandible angle (TMA) at neutral and extended positions. Modified Cormack-Lehane score (MCLS) was obtained by an anesthesiologist. Mann-Whitney U test was used to compare the control with DLE group. RESULTS: The ages of patients ranged from 23 to 80 years with a mean of 48.7 years. The LE score was highly correlated with MCLS (r=0.676, p<.001). Among physical measurements, HMD at neutral position (p=.047) and TMD (p=.016), VTD (p=.005), SMD (p=.019) and VITD (p=.040) at extended position had a statistical significance. Among radiologic measurements, HMD (p=.008) and TMD (p=.005) at neutral position, and TMD (p=.037) and VTD (p=.034) at extended position had a statistical significance. CONCLUSION: The new classification is a reliable system to evaluate the extent of laryngeal exposure during suspension laryngoscopy. The physical and radiologic measurements can be helpful to predict the difficult laryngeal exposure.