CT Evaluation of Laryngotracheal Trauma

Laryngotracheal injuries are rare, and typically associated with multisystem trauma. They may be blunt or penetrating in nature, and are in the great majority of cases related to motor vehicle accidents or ÒclotheslineÓ injuries with a small percentage due to direct blows sustained during assaults or athletic contests, hanging or manual strangulation, or other less common etiologies including iatrogenic causes. Missed diagnoses or mismanagement may result in the patient's death or significant long-term morbidity. The radiologist must be familiar with the normal computed tomographic (CT) appearance of laryngotracheal anatomy to correctly interpret CT studies following injury, and must also be aware of the central role that CT plays in diagnosis, management, and selection of therapy. This should include an understanding of the Shaefer classification of laryngeal injuries that is based on a combination of the CT and endoscopic findings. Although an acceptable evaluation of the traumatized larynx is obtainable with most commercially available CT scanners, optimal studies are produced by CT devices capable of spiral technique and subsecond scan times, particularly in regard to their ability to generate thin retrospectively reconstructed two-dimensional (2D) axial sections, 2D coronal and sagittal images, and three-dimensional (3D) images. Our discussion of laryngotracheal injuries is divided into four parts. Part 1 deals with injuries to the endolaryngeal soft tissues structures, including the mucosa, vocal cords, and deep compartments. The ability of CT to demonstrate endolaryngeal edema and hematoma, vocal cord injuries, subcutaneous emphysema, and aspirated radiopaque foreign bodies is discussed along with its inability to demonstrate the site of mucosal perforations or degloving injuries. Part II deals with fractures of the hyoid bone, epiglottis, and thyroid and cricoid cartilages, while Part III discusses dislocations of the cricoarytenoid and cricothyroid joints. Finally, Part IV discusses laryngotracheal separation, the most immediately life-threatening laryngotracheal injury, and the difficulties inherent in making this diagnosis prospectively by CT.