Histologic study of the growth of the subglottis after interruption of the circular structure of the cricoid

In a previous study in growing rabbits it was demonstrated that after resection of a ventral part of the cricoid the lumen of the subglottic airway developed normal size during further growth up to the adult stage. Histologic investigations of these cases suggest that a subepithelial network of elastic fibres, ventrally suspended to the thyroid and the tracheal rings, ensures the airway lumen and prevents the development of a subglottic stenosis. Resection of a ventral part of the cricoid including the adjacent soft tissue lining of the airway causes an irreversible loss of the supporting elastic layer and the formation of scar tissue resulting in a stenosis. It was concluded that the larynx and trachea can be considered as an inner, elastic tube (= conus elasticus) lined with epithelium, suspended to an outer, segmented cartilaginous tube. At the level of the subglottis an intact conus elasticus is of more importance for the normal development of the airway lumen in young rabbits than an intact ventral half of the cricoid ring.     

Morphometric study of the growth of the subglottis after interruption of the circular structure of the cricoid

In young rabbits the growth of the subglottis was studied over a period of 20 weeks after interruption of the circularity of the cricoid on the ventral side. In all cases the cricoid developed into a U-like structure which did not cause an airway narrowing. However, a cricoid lesion combined with an injury to the soft tissue lining led up to a subglottic stenosis. It was concluded that when the soft tissue layer is undamaged, an intact circular structure of the cricoid is not compulsory for the normal development of the subglottis.     

Treatment of carcinoma of the base of the tongue and the larynx

Cancer of the base of the tongue and the larynx is usually treated primarily with irradiation to 6,000 rads. Persistence of tumor after irradiation is common and requires a logical, thoughtful approach designed to augment all tissues removed. Careful preoperative planning and the use of the lateral approach to the base of the tongue, in conjunction with pharyngostome and laryngostome formation allows wide resection of the cancer. Preservation of the function of speech and swallowing, and preservation of the mandibular contour are important, and correlate closely with carotid artery protection. Five different methods of approach to the problem are analyzed and presented.