Injury- and age-linked differences in wound healing and stenosis formation in the subglottis

We studied the effects of superficial and deep endolaryngeal trauma of the subglottic airway in young and adult rabbits. In both age groups a soft stenosis was formed as long as the cartilaginous cricoid ring is not involved. This stenosis comprised a thickened subepithelial zone of scar tissue, separated from the cricoid cartilage by a layer of fatty tissue. Injury of the internal side of the cricoid cartilage induced a compact mass of scar tissue with local differentiation into fibrocartilage. In young animals only, injury of the cartilage led to remodelling of the cricoid ring (indentation or collapse of the traumatized sectors). On the basis of the differentiating effects of age and depth of the lesion, three histopathological types of subglottic stenosis were distinguished. The experimental results provide an explanation for the variability in the histopathological features of the wall of the stenotic subglottic airway, as observed in biopsies and postmortem specimens.