Definition and Overview

Subglottic stenosis (SGS) is the third most common airway problem in children. It is the narrowing of the subglottic airway or the part of the windpipe located just below the vocal folds. A person can be born with it or it can develop later in life. It can also occur spontaneously for unknown reasons.

SGS can cause mild or severe airway obstruction. It also often causes recurrent croup. Croup is the inflammation of the larynx and trachea in children. In most severe cases, SGS is a medical emergency. It can lead to death if not treated promptly. But the condition is relatively rare.

SGS’s severity depends on the degree of blockage. Grade 1 means that the obstruction is less than 50%. Grade 2, on the other hand, means that the obstruction is more than 51% but less than 70%. Grade 3 means that the obstruction is more than 71% but not more than 99%. Grade four, which is the most severe, means that the subglottic airway is totally closed.

SGS is treated with medications or surgery.

Causes of Condition

Babies can be born with SGS if their airway fails to form completely while inside the womb. As a result, the diameter of their subglottic airway is less than 4mm. SGS is also linked to some disorders that occur when the body’s immune system mistakenly attacks healthy cells and tissues.

Meanwhile, acquired SGS often occurs when premature babies are intubated. Intubation involves placing a breathing tube in the throat to help patients breathe properly. SGS can also occur if the area is infected or damaged by traumatic injuries. Another possible cause is gastrointestinal reflux. This causes acid from the stomach to back up to the oesophagus. This can irritate and inflame the airway.

In some cases, the cause of SGS is unknown.

Key Symptoms

One of the early signs of SGS is stridor. This is a wheezing sound that babies make when their windpipe is partially blocked. But this symptom is not exclusive to SGS. It can also be associated to pulmonary, bronchial, and tracheal lesions. As mentioned above, SGS can also cause recurrent croup. Other signs include shortness of breath, poor feeding, and failure to thrive.

In more severe cases, patients can present with a weak or hoarse voice. SGS can also cause vocal cord paralysis.

Who to See and Types of Treatments Available

SGS is diagnosed with microlaryngoscopy and bronchoscopy (MLB). It involves inserting a thin, flexible tube with a camera into the airway through the mouth. It is often used when children show signs of breathing problems. It requires general anaesthesia. This means that the patient will not feel any pain during the procedure. They may also not remember the test. This procedure comes with risks. The child’s airway could get damaged. They can also develop a sore throat. The patient has to stay in the hospital overnight. The results are made available to parents within 24 hours after the test.

Treatment is not necessary if SGS is mild and if there are no symptoms. But doctors would want to monitor it with periodic endoscopy to ensure that it is not progressing.

If symptoms are severe, surgery becomes an option. It is done to widen the airway. Grafts of cartilage taken from another part of the patient’s body and a plastic stent are used to ensure that the subglottic airway stays open. The stent is removed six weeks after surgery.

The subglottic airway can also be widened through endoscopy. For this procedure, an endoscope is inserted into the airway through the mouth. Once it reaches the narrowed part, a small balloon is inflated to widen the opening. Excess and scar tissue that may be causing the blockage can be removed or shaved off. This may be done using laser energy or small rotating blades.

The child will undergo another endoscopy weeks after surgery. Its purpose is to check the airway to ensure that it has healed well. The test also looks for possible complications. Patients may require speech therapy. This can help them deal with changes brought on by their widened vocal cords.

Very severe cases of SGS may require a tracheostomy. This is an artificial opening in the lower part of the neck. It helps patients breathe oxygen by bypassing the nose and mouth. For this procedure, traditional open surgery is needed.

References:

  • Fearon B, Cotton R. Surgical correction of subglottic stenosis of the larynx in infants and children. Progress report. Ann Otol Rhinol Laryngol. 1974 Jul-Aug. 83(4):428-31.

  • Monnier P, Savary M, Chapuis G. Partial cricoid resection with primary tracheal anastomosis for subglottic stenosis in infants and children. Laryngoscope. 1993 Nov. 103(11 Pt 1):1273-83.

  • Rizzi MD, Thorne MC, Zur KB, Jacobs IN. Laryngotracheal reconstruction with posterior costal cartilage grafts: outcomes at a single institution. Otolaryngol Head Neck Surg. 2009 Mar;140(3):348-53. Cited in PubMed; PMID 19248941.

  • Rao A, Starritt N, Park J, Kubba H, Clement A. Subglottic stenosis and socio-economic deprivation: a 6-year review of the Scottish National Service for Paediatric Complex Airway Reconstruction. Int J Pediatr Otorhinolaryngol. 2013 Jul. 77(7):1132-4.

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