[Etiopathogenesis and biodynamics of closed laryngo-tracheal injuries]

The blunt laryngotracheal trauma, once quite a rare phenomenon, has become quite relevant today, particularly because of the great increase in automotive traffic. It was, therefore, felt knowledge of the etiopathogenesis and biodynamics of this form of trauma is important for proper diagnosis and treatment. After having noted that the literature in this regard is generally incomplete and fragmentary, the authors felt it worth compiling the various etiopathogenesis and biodynamic factors involved; characteristics of blunt laryngotracheal trauma. Three basic elements of this form of trauma were studied. These are: trauma subject, trauma forces and impact plane. The biodynamic mechanisms responsible for the damage caused to the laryngotracheal skeleton and its soft parts have been analyzed. Finally, a case study was made including 99 cases drawn from international literature and 23 cases which had come under observation by the authors. The purpose of this analysis was to determine the frequency of various etiologies in relation to trauma type and site. The difficulties involved in drawing these simple data from the literature is underlined. This stems from the fact that often the various authors report overall data failing to give the etiology and site of individual cases. Traffic accidents have proved to be the cause of 80% of all such traumas and 90% of those with fracture, dislocation or separation of the laryngotracheal skeleton. The most serious lesions are to be seen in cases of frontal trauma. In the elastic cartilage of young people, the elastic snapback is of particular significance in the genesis of damage to the soft tissues. The most frequently encountered lesion is fracture of the thyroid cartilage alone while fracture of the cricoid alone is quite unusual. Fractures or detachment within the cricoid-tracheal area is quite common. In 85% of the cases cricoid cartilage involvement is associated with that of the tracheal cartilage. The authors assert that, due to a question of resistance, cricoid fracture traumas almost always involve the trachea while thyroid cartilage fractures act as a relief, letting off and absorbing the forces, thus preventing cricoid involvement. On the basis of these considerations the authors feel it fitting to classify the blunt laryngotracheal traumas into three groups according to topography: supraglottic laryngeal trauma with or without involvement of the glottis; subglottic laryngeal trauma, generally associated with the trachea and only rarely involving the glottic region; isolated trauma of the cervical trachea.