Radiation Exposure Alters Airway Deformability during Laryngoscopy

by Amy E. Hamaker •

What is the effect of therapeutic radiation exposure on airway volume, tissue deformation, and bony structure displacement in the setting of operative laryngoscopy?

Bottom Line: Individuals with prior therapeutic radiation exposure to the upper aerodigestive tract differ from nonirradiated subjects with respect to airway deformation and bony structure translation during laryngoscopy.

Background: Variations in head and neck anatomy can have major implications regarding airway management. The difficult airway can present potentially life-threatening situations during intubation, and impact adequate exposure and margin control during operative laryngoscopy. In recent years, a number of studies have sought to measure structures of the upper airway using three-dimensional models derived from computed tomography (CT) or magnetic resonance imaging (MRI), and some have used this approach to assess airway anatomy in various clinical scenarios. However, despite advances in the computational modeling tools available for image analysis, no prior studies have evaluated the effect of therapeutic radiation exposure on airway volume, tissue deformation, or bony structure displacement in the setting of operative laryngoscopy.

Study design: Retrospective review.

Setting: Section of Otolaryngology, Dartmouth-Hitchcock Medical Center, Lebanon, N.H.

Synopsis: Fifteen participants undergoing suspension laryngoscopy for suspected malignancies of the head and neck were enrolled in the study. Five had previously received therapeutic radiation for a head and neck malignancy (of which four received combination radiation therapy and chemotherapy), while the remaining 10 had neither a prior history of head and neck malignancies nor a history of previous therapeutic radiation exposure. The majority of study participants were male (13/15, 87%), with an average age of 66 years (range: 44–77) and average body mass index of 26.5 (range: 18.0–39.9). CT images obtained before and during laryngoscope insertion (“uninstrumented” and “instrumented,” respectively) were used to reconstruct 3D representations of the pharyngeal airway, hyoid, and mandible.

The study revealed substantial differences in pharyngeal airway deformability between previously irradiated and nonirradiated participants in the context of clinically indicated suspension laryngoscopy. Specifically, previously irradiated patients were found to have an approximately 40% reduction in pharyngeal airway volume following laryngoscope insertion relative to nonirradiated patients. The region of the airway that differed most substantially with respect to volume between these two groups was in direct approximation to the laryngoscope itself, with minor differences in airway volume observed more distal to the laryngoscope. The reduced pharyngeal airway volume observed in previously irradiated subjects relative to nonirradiated subjects in the instrumented state could not be accounted for by differences in other measured variables, including age, sex, BMI, Mallampati score, airway grade, thyromental distance, neck range of motion, and undeformed airway volume.

Citation: Rees CA, Wu X, Eisen EA, Pastel DA, Halter RJ, Paydarfar JA. Radiation exposure alters airway deformability and bony structure displacement during laryngoscopy. Laryngoscope Inv Otolaryngol. Published October 22, 2019. doi: 10.1002/lio2.311.