The subglottis is the part of the voice box just below the vocal cords. Subglottic stenosis means that the area is narrowed. This can lead to stridor / noisy breathing, breathing difficulties, recurrent croup, blue episodes, or poor growth.
What causes subglottic stenosis?
Subglottic stenosis can be present from birth (this is called congenital) or it can develop after birth (this is called acquired). Acquired subglottic stenosis is much more common that congenital.
Acquired subglottic stenosis happens due to scarring in the subglottis. The process starts when the subglottis becomes irritated, usually this is due to intubation related to intensive care stay. When a baby is in intensive care, they often need a tube in their airway to help them breathe. But the fact that the tube is there can irritate the airway, especially subglottis. The baby needs the tube to breathe, but an unfortunate side effect can be irritation of the subglottis. This irritation can lead to development of scar tissue in the subglottis. The scar tissue then leads to narrowing in the subglottis, which is the subglottic stenosis.
Severity classification of subglottic stenosis
The severity of subglottic stenosis is classified according to how much narrower the airway is compared to what it should be. The classification is called the Cotton-Myer system, and is based on the cross sectional area of the subglottis, in other words the amount of space that there is for your child to breathe through.
Grade 1 means that the airway obstruction is up to 50%, so that is half of the normal area
Grade 2 means the obstruction is between 51 and 70% of the normal area
Grade 3 means the obstruction is between 71 and 99% of the normal area
Grade 4 means that the airway is completely occluded
The diagnosis of subglottic stenosis and assessment of its severity will be made in the operating theatre during airway evaluation.
As you might expect, the severity of your child's symptoms will depend on how severe the narrowing is. Children with grade 1 subglottic stenosis may have few symptoms, those with grade 3 will struggle, and those with grade 4 will not be able to breathe at all unless they have a tracheostomy.
How is subglottic stenosis treated?
Treatment is tailored to each individual child. It will depend on the severity of narrowing, your child's symptoms, how long the narrowing has been present, and your child's overall health.
If the symptoms are mild and narrowing is mild, a good option may be to just wait for your child to get older, because symptoms related to narrowing often improve with age.
Other options include tracheostomy, stretching of the area with a balloon, reconstruction of the area using cartilage obtained from the child's ribs, or surgical removal of the narrowed area.
Management of subglottic stenosis is complex, and usually carried out in specialist centres.