Wound healing of laryngeal trauma and the development of subglottic stenosis.

Investigations of wound healing of the cricoid cartilage, its epithelium and subepithelial layer were performed in an experimental model. Each experiment comprised 10 young rabbits at the age of 4 weeks with a standard follow-up period of 20 weeks (to adulthood). Endolaryngeal lesions could be restricted to the soft tissue lining (epithelium + subepithelial layer), or they could also involve the perichondrium and the inner side of the cartilage. Splits were performed at different sites: anteriorly, bilaterally or antero-posteriorly, along with additional combinations. Assessment was performed by endoscopy and histopathology. The latter comprised 5-J1m sectioning in the horizontal and sagittal planes. The structure of the larynx of rabbits remarkably corresponds with that of man: the organization of the different cartilaginous parts and their interrelation, the structure of the respiratory epithelium and the subepithelium with vessels, glands, and most important, the elastic system [1]. An endolaryngeal injury with traumatization of the epithelium, the subepithelial layer, and the internal side of the cricoid can lead to major anomalies just I week after surgery. The epithelium has already regenerated, but in disorderly fashion with thick, multilayered parts next to thin parts with cubic cells. Enormous thickening of the subepithelial region demonstrates a large quantity of blood vessels and a loose netting of fibrous tissue. Even the cartilage demonstrates important deformations, of which inconsistent thickness is the most conspicuous. The lumen has narrowed, sometimes to a degree incompatible with life. Twenty weeks after intervention, the oval cricoid ring is transformed into a deformed, sometimes pearshaped ring with sideward or anterior collapse; the lumen has been decreased