Image: Normal laryngeal and tracheal anatomy
The larynx is a structure composed primarily of cartilage, muscle, and other soft tissues. It sits above the trachea (windpipe), and plays an important role in a child’s ability to breathe, speak, and swallow. The larynx has three main parts: the supraglottis, glottis and subglottis. The supraglottis is the part of the larynx that is above the vocal cords. The glottis is another term for the vocal cords (also called vocal folds). The subglottis is the area just below the vocal cords, and it is unique because it is made up of the only complete ring of cartilage that normally occurs in the airway. Each location in the larynx has the ability to become injured.
The trachea, or windpipe, is composed of incomplete rings of cartilage that are shaped like horseshoes that line the roof of the airway. The floor of the windpipe is made up of a band of muscle and soft tissue. The trachea has the ability to expand and contract when we breathe, and injury to the trachea may include scarring or narrowing of the airway (stenosis).
Stenosis is a term used to describe a narrowing of the airway. Stenosis can occur in any of the three parts of the larynx, or in the trachea itself. If the narrowing is severe, it can affect a child’s ability to breathe and cough up secretions. Airway stenosis can also affect the voice, the ability to swallow, and can make mild cold symptoms much more severe.
Stenosis of the larynx or trachea in children can be present at birth in a small proportion of children. This is called “congenital” airway stenosis. More commonly, narrowing or stenosis of the airway occurs after an injury to the airway. The most common kind of airway injury occurs in newborn patients who require intubation (the placement of a breathing tube) after birth. This is more common in children who are born prematurely and require a mechanical ventilator while their lungs develop. Although this form of mechanical ventilation is lifesaving in the premature child, it also has the risk of causing airway scarring that leads to airway narrowing. The subglottis (area immediately below the vocal cords) is the most likely site of airway narrowing due to prolonged intubation. This is commonly referred to as Subglottic Stenosis.
Diagnosis of airway narrowing (stenosis) requires a visit with a Ear Nose and Throat specialist (Otolaryngologist) for a thorough physical examination, and an endoscopic evaluation of the airway. Children with airway stenosis may have symptoms including the inability to cough up secretions, severe shortness of breath, noisy breathing, difficulty eating, or recurrent croup-like infections at a frequency or age that is not typical. Other times, children with airway stenosis may have no symptoms. Premature infants with airway stenosis are frequently diagnosed only after the breathing tube is removed and they are unable to breathe adequately on their own. In children with a suspicion for airway stenosis, a microlaryngoscopy and bronchoscopy are performed. This involves using a microscope and camera to look at the larynx and the trachea, identifying and measuring the airway narrowing, with the child under anesthesia in the operating room.
Treatment of airway stenosis depends on the location and the severity of narrowing. If mild, treatment may only include observation. If severe, endoscopic interventions or surgical reconstruction of the airway may be required.
Endoscopic interventions are performed through the mouth, and do not require any incisions on the skin. Several endoscopic interventions have been designed to treat children with airway obstruction. Some of these include balloon dilation, endoscopic cricoid split procedures, and endoscopic posterior cartilage grafting procedures.
Open interventions are performed through an incision in the neck. This incision usually heals very well, and can often be incorporated into the patient’s tracheostomy stoma if one exists. These open surgical procedures designed to treat airway stenosis are often called “laryngotracheoplasty (LTP)” or “laryngotracheal reconstruction (LTR)”, and encompass a wide variety of different techniques. It is important to remember that not all surgical procedures are appropriate for every child. Each procedure has its own set of risks and benefits, and should be carefully selected only after a comprehensive evaluation with a pediatric Ear Nose and Throat specialist (Otolaryngologist).
The primary goal of airway reconstruction is to widen the location of narrowing. There are three main categories of airway reconstruction designed to achieve this:
Airway reconstruction is often performed in a patient who has a tracheostomy in place. A single stage procedure refers to an airway reconstruction technique that is performed at the same time that the tracheostomy tube is removed. This is often performed for less-severe stenosis, but may be performed for patients with severe stenosis under select circumstances.
A double-stage procedure refers to an airway reconstruction that is performed and allowed to heal completely before removal of the tracheostomy tube. This is frequently performed for more severe stenosis, or in revision airway reconstruction.