What is subglottic stenosis?
Subglottic stenosis (SGS) is a narrowing of the airway below the vocal cords (subglottis) and above the trachea. Subglottic stenosis will involve narrowing of the cricoid, the only complete cartilage ring in the airway. This narrowing is often caused by scarring in the larynx just below the vocal cords but may also involve the vocal cords and affect the voice as well.
Subglottic stenosis comes in two forms: acquired and congenital.
Endoscopic view of congenital subglottic stenosis.
- Acquired subglottic stenosis often occurs after long periods of intubation and ventilation for respiratory problems.
- Congenital subglottic stenosis occurs as a rare birth defect and may be associated with other genetic syndromes and conditions. The airway remains narrow because the airway cartilage did not form properly before birth.
The exact cause of the scarring is not known at this time. Individual neonatal intensive care units only have small numbers of infants who develop this condition and not enough patients in each individual unit to have statistically significant data. Multicenter studies are needed to better understand the cause of subglottic stenosis.
However, current evidence suggests a number of important risk factors include prolonged intubation, low birth weight, reflux, sepsis and others. Furthermore, a tracheostomy may cause stenosis or malacia (softening) at the tracheostomy site especially if it is placed high in the trachea.
Signs and symptoms
The signs of subglottic stenosis include:
- Noisy breathing (stridor)
- Respiratory distress
- Recurring croup
- Inability to breathe without a tracheostomy tube
Testing and diagnosis
The history of specific risk factors is important in reaching the diagnosis. Your doctor will look for prolonged intubation and ventilation, extreme prematurity, low birth weight, chronic bronchopulmonary dysplasia (lung disease) and gastroesophageal reflux as causes of the respiratory distress.
Further evaluation is done with X-rays. Neck X-rays may reveal subglottic narrowing or subglottic masses. On these films the trachea is evaluated for tracheal narrowing or stenosis or complete rings. Definitive diagnosis is made on endoscopy with microlaryngoscopy and bronchoscopy.
The surgeon may determine the size of the airway with a plastic endotracheal tube. The severity of subglottic stenosis is graded as shown in the figure above.
During the airway center visit, your child will undergo a evaluation by a pediatric gastroenterologist as well as a nutritional assessment. A pediatric pulmonologist may also evaluate your child's lung status and a speech and swallowing therapist may evaluate swallow and voice. These specialists will evaluate your child and determine the need for further tests. Our surgical scheduling team will arrange a full endoscopic and GI evaluation in the operating room. This will include a microlaryngoscopy, bronchoscopy (MLB) and upper GI endoscopy (EGD), impedance probe testing and pulmonary scopes.
During the EGD, biopsies will be taken from multiple levels up and down the aero-digestive tract and these will be screened for signs of inflammation suggestive of reflux (GERD) or food allergy inflammation (eosinophilic esophagitis). The patient is considered suitable for airway surgery when the stenosis has matured, the GERD is under control and the pulmonary status is stable. If the GERD is not under control then the patients medication may be adjusted or changed and repeat testing will need to be done. In rare cases anti-reflux surgery may be needed.
In addition, prior to reconstructive airway surgery the child will undergo a formal feeding evaluation which includes an endoscopic evaluation of swallowing (FEES) performed in the office or a modified barium swallow. If your child does not accept food and relies exclusively on a feeding tube then a flexible scope with a few drops of green dye will be used to detect pooling and aspiration. This is to make sure that your child will be able to swallow well and protect their new and enlarged airway after reconstruction. If these studies look reasonably normal then the child can undergo surgical treatment for the subglottic stenosis.
Subglottic stenosis treatment depends upon how severely it impacts the child's breathing. In addition, other medical conditions the patient has may influence the decision on how to treat the stenosis surgically. There are a wide range of treatment options which depends upon these factors and more.
Treatment for mild cases
Mild subglottic stenosis: Grades 1 and 2 stenosis, as well as thin webs and bands.
- Observation. The mildest cases where patients may remain asymptomatic may just require close observation. Most often conditions will improve over time with the growth of the airway. Grade 1 congenital stenosis often improves on its own and requires no intervention. Observation is critical for children with mild subglottic stenosis, because they are more likely to have problems breathing with common upper respiratory illnesses (colds, bronchitis).
- Endoscopic surgery. Some cases of mild stenosis may need to be treated endoscopically. Thin webs may be divided with a sickle knife and dilated with the angioplasty balloon. Thicker stenosis may be balloon dilated as well. The soft stenosis and subglottic stenosis related to systemic diseases such as GERD and Wegener’s granulomatosis, is best treated with airway balloon dilation. Lasers and microdebriders (powered rotating blades which shave off soft tissue) are employed as well to remove segmental portions of scar tissue.
Treatment for Severe Cases
Severe subglottic stenosis: Grades 3 and 4 stenosis.
Almost all patients with severe subglottic stenosis will require a tracheostomy tube to breathe. Often, open surgery with laryngotracheal reconstruction surgery (LTR) or partial cricotracheal resection (CTR) is needed to correct the stenosis and to achieve decannulation (removal of tracheostomy tube).
Subglottic stenosis repair
Discussion of subglottic stenosis and its treatment — laryngotracheal reconstruction
LTR. In laryngotracheal reconstruction surgery, the surgeon uses pieces of rib cartilage to expand the airway. The surgeon makes a vertical cut through the narrowed airway from the outside to repair the damaged section inside. The cartilage grafts are shaped with a scalpel into an elliptical shape. The posterior (back) graft is also an elliptical shape with a ledge to lock it into position behind the cut edges of the cricoid (cartilage). The grafts may be placed in the anterior or posterior position or both at the same time. LTR may be performed in a single stage where the tracheotomy tube is removed at the time of surgery or double stage where the surgery is performed with the tracheotomy tube in place. When the airway is healed the tracheotomy tube is removed at a later date. There are specific indications to perform LTR surgery in a single stage or in a staged manner and the decision is individualized to the specifics of the child.
CTR. The most severe cases may be amenable to partial cricotracheal resection when the scarring is limited to the subglottis and spares the vocal cords. In this procedure the scar tissue and most of the anterior cricoid (cartilage) is cut out and the normal trachea is brought up to replace it. CTR may also be performed single stage in more straightforward situations and staged in more complex cases such as revision surgery.
Outlook and follow-up care
The long-term success rates of both LTR and CTR are outstanding.
CHOP has reported an overall decannulation rate of 96 percent for children undergoing posterior graft LTR. This means that the ultimate decannulation rate is 96 percent, but certain children may require more than one procedure.
We found a 70 percent operation-specific decannulation rate for patients undergoing a double stage LTR. Ultimately, 95 percent of these patients are decannulated. The operation specific decannulation rate is the rate of successful decannulation after one major operation.
We found an operation specific decannulation rate of 92 percent for single-stage LTR and an ultimate decannulation rate of 100 percent. These results compare favorably to other reports in the literature. Moreover, the overall success rate depends on many factors including pathology, patient’s medical condition and previous failed surgery as well as other unknown intrinsic factors.
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