MANDIBULOHYOID DISTANCE IN DIFFICULT LARYNGOSCOPY

We studied radiographically 11 patients in whom direct laryngoscopy pr oved difficult and 100 control (general population) subjects. The vert ical distance between the mandible and the hyoid bone (mandibulohyoid distance) was measured and the positions of the mandibular angle and h yoid bone determined in relation to the cervical vertebrae. We found t hat the mandibulohyoid distance was substantially longer in patients w hose trachea was difficult to intubate; the mandibular angle tended to be positioned more rostrally in both men and women, and the hyoid bon e tended to be positioned more caudally in women. This suggests that a relatively short mandibular ramus or a relatively caudal larynx may b e important, unfavourable anatomic,factors in difficult laryngoscopy.