Background and Goal of Study: Several anatomical factors like micro- or rethrognathia, macroglossia, tempormandibular joint affections, and others are known to limit the view at laryngeal structures during direct laryngoscopy. In this study we investigated the hypothesis that the anatomic position of the vocal cords related to the cervical vertebrae may give a hint for possible difficult laryngoscopy.
Materials and Methods: After approval of the local Ethics Committee and written informed consent we included 142 patients undergoing neurosurgical procedures into the study. In all patients a magnetic resonance tomography of head and neck (Figure 1) had been performed as part of diagnostic evaluation of the underlying disease. Difficulty of laryngoscopy (without BURP1) has been rated according to the classification of Cormack-Lehane2, whereby Cormack 1 and 2 were rated as easy and Cormack 3 and 4 as difficult laryngoscopies. Statistical analysis was done using Chi-square test, p< 0.05 was considered significant.
Results and Discussion: 142 patients between 19 and 82 years were enrolled in the study. Difficult laryngoscopy was more frequent in patients with cranial or caudal position of the vocal cord level (figure 2, p< 0.01)
Conclusion(s): There is a correlation between difficult laryngoscopy and the anatomic position of the vocal cords related to the cervical vertebrae. Anesthesiologists should take advantage of exisiting imaging of the cervical spine when assessing the patient's airway.
1. Knill, R.L. Can J Anaesth 1993; 40:279-82; (2) Cormack R.S. und Lehane, J. Anaesthesia 1984; 39:1105-11