Abstract
Laryngeal granulomas after endotracheal intubation were observed near the vocal process. The pathogenesis of the laryngeal granuloma has not yet been established. The purpose of this investigation was to clarify the cause of these granulomas. Two different experimental procedures were adapted for this study. In the first series, 54 intact hemilarynges obtained from 35 human cadavers with known histories of intubation, were studied. Extent of injury to the vocal process was observed macroscopically and histologically. In the second series, the vocal processes of 16 mongrels were injured using a rasp, and each stage of the healing process was histologically observed. The results are summarized as follows; I. Injury to the vocal process after intubation and caused factors. 1) A triangular-shaped injury exists posteriorly to the area which is clinically termed vocal process. 2) The lesion begins as a defect in the covering mucosal epithelium and pro-gresses in stepwise fashion as a congestion of the layer of mucosal propria, a necrosis or a defect of the layer of mucosal propria, and exposure of the arytenoid cartilage as the terminal stage of pathogenesis. 3) With regard to the location and extent of injury, lateral preference wasnot observed. 4) A sexual predominance of injury was not recognized, however, severe damage to the vocal process extending to the cartilageneous membrane and arytenoid cartilage occurring in cases with intubation for periods longer than 24 hours, was observed in the female. Furthermore, a comparison between the length of vocal cord and diameter of the ventilating tube revealed that the tube used in females was larger than that used in males. 5) A lesion is not worsened by hypoproteinemia, hypoalbuminemia or anemia, which was generally believed to be the cause. 6) Usage of a respirator was not a precipitating factor of injuries. On the contrary, non-use of a respirator led to more severe injuries in cases of intubation of longer than 12 hours. II. Healing of injury to the vocal process. 1) Two weeks are required for complete healing in cases where injury extends to the epithelium and submucous proper layer, while four weeks are required when injury extends to the arytenoid cartilage. 2) Healing of injury beyond the arytenoid cartilage isaccompanied by growth of a secondary granuloma adjacent to the site of the original lesion. 3) This second granuloma begins to develop as a wide crater-like lesion which later changes to a long stalk. Accordingly, the arytenoid cartilage becomes necrotic with development of the granuloma.
