Subglottic cysts are fluid-filled lesions in the lower part of the larynx, or subglottis, just below the vocal cords. They are a fairly common cause of airway blockage in children. There may be one or more cysts that block the airway below the larynx. Subglottic cysts are often treatable. They can cause total airway obstruction and even death if they are large and not treated right away.

What Causes Subglottic Cysts?

Subglottic cysts often result from intubation or ventilator use. The length of intubation may be brief, but after several hours, days or even months, noisy breathing (stridor) may develop with signs of upper airway obstruction. Most cases of subglottic cysts occur in premature infants, as the need for intubation in these children is more common.

What Are the Symptoms of Subglottic Cysts?

The subglottis, or lower part of the larynx, is just below the vocal cords. Because these cysts partially block the airway or put pressure on the vocal cords, signs and symptoms of subglottic cysts can include:

• Noisy breathing (stridor): The cysts may interfere with the airway, causing a noisy raspy or rattling sound when breathing in and / or out.
• Trouble breathing: Breathing can be hard depending on the degree of blockage caused by the cyst. If the blockage is too large, it can be fatal.
• Recurrent croup: The narrower airway passage causes a barking sound when the child coughs.
• Hoarseness: The cysts may add pressure to the vocal cords, causing hoarseness.
• Obstructive apnea: Breathing may stop sometimes during sleep. This is due to the blockage in the airway caused by the cyst.

How Are Subglottic Cysts Diagnosed?

Subglottic cysts can be misdiagnosed as laryngomalacia, asthma, croup or other diseases and conditions. It is vital that a diagnosis be made because the blockage of the airway can be fatal if severe. Subglottic cysts may be diagnosed by any of the following tests:

• Endoscopy — A flexible fiber optic tube passed through the child’s mouth. The doctor will look for cysts along the subglottis.
• Neck X-ray — An X-ray allows the doctor to see if one or more cysts are present. They can also see if the child’s symptoms are being caused by some other reason, such as a swallowed object.
• Flexible laryngoscopy — A flexible tube that allows the doctor to see the throat better. Laryngoscopy allows the doctor to see if one or more cysts are present. They can also see if the child’s symptoms are being caused by some other reason, such as laryngomalacia.

How Are Subglottic Cysts Treated?

Treatment depends on the following:

• The number of cysts
• The size of the cyst(s)
• The location of the cyst(s)
• The degree of blockage

During an endoscopy procedure, your doctor may deflate the cyst, allowing fluid to drain out of it. Your child will likely stay overnight in the hospital to make sure their airway remains open and they can breathe easily. An endoscopy may be done a few months later to ensure the cysts don’t return.

What Is the Long-Term Outlook for Subglottic Cysts?

Cysts may recur. There is a risk of narrowing of the airway below the vocal cords (subglottic stenosis) as a result of the cysts. It is vital for these children to have long-term follow-up monitoring and care.

When to Call Your Doctor

Call 911 right away if your child:

• Cannot breathe
• Turns blue
• Is unconscious

Call your doctor if your child:

• Develops stridor
• Has trouble breathing