Although our report applies to only a single institution in a single year, after reviewing the literature we think a downward trend exists in the incidence of neonatal subglottic stenosis in the late 1990s. The current incidence of neonatal subglottic stenosis is likely between 0.0% and 2.0%.

SummaryOne of the most challenging problems confronting otolaryngologists today remains the management of subglottic stenosis (SGS) in infants and children. It is a problem of decreased airway calibre, usually associated with prolonged intubation. T he pathophysiology of an intubated airway becoming stenotic is not fully understood. Although an ideal animal model for studying SGS does not currently exist, several studies have used the rabbit's airway as a wound healing model. In order to establish such a model in the rabbit, sizes of the normal rabbit larynx must be measured in order to compare them to the diseased airway. Measuring the airway diameters of 35 rabbits ranging from 2.3±5.1 kg, the average airway at the level of the cricoid was found to be 5.81 mm (ventral±dorsal ) by 5.41 mm (lateral ). T hese dim ensions did not vary significantly with animal weight.

Laryngeal wound healing is essential following laryngotracheal surgery. Patients with poor wound healing develop poor epithelial closure and increased granulation tissue which cause a stenosis of the repaired airway. Transforming growth factor-beta3 has been shown to enhance wound healing in cutaneous wounds, but has never been used in the airway. This study utilized a rabbit laryngeal wound-healing model that has been shown to be reproducible with limited morbidity. Thirty-four rabbits underwent a cricoid-split operation with collagen sponge insertion. All animals were classified randomly into three groups: local administration of placebo (Group G1, n = 13), 0.18 microg transforming growth factor-beta3 (Group G2, n = 11) and of 1.0 microg transforming growth factor-beta3 (Group G3, n = 10). All animals survived the postoperative period without respiratory distress. The airway was harvested six days after surgery and assessed by light microscopy. Histologic evidence for healing was subjectively graded by two blinded, independent investigators, and the results were statistically analyzed for significance. A significant improvement in the epithelial closure (p < 0.01) and subepithelial connective tissue closure (p < 0.005) was found in the 1.0 microg transforming growth factor-beta3 group (G3) compared with the placebo group (G1). Analysis of the 0.18 microg transforming growth factor-beta3 group (G2) did not reveal any significant differences compared with the placebo group (G1). These results suggest an application for transforming growth factor-beta3 in accelerating wound healing in the larynx.