Idiopathic Subglottic Stenosis
What is idiopathic subglottic stenosis?
People who have idiopathic subglottic stenosis (iSGS) have a narrowing (called stenosis) in the part of the trachea (windpipe) known as the subglottis; this is the narrowest part of the airway, just below the vocal cords. Most people with iSGS have scar tissue (fibrosis) and inflammation in the affected area. In iSGS there is no known cause for the condition (this is the meaning of the term “idiopathic”). iSGS occurs almost exclusively in women between the ages of 30 and 50, but has also been reported in younger women and older adults. Because almost all cases of iSGS occur in women around the time of menopause, it’s theorized that the condition may be linked to the hormonal changes. Other possible causes include collagen vascular disease, trauma from coughing, and gastroesophageal reflux disease (GERD).
What are the symptoms of idiopathic subglottic stenosis?
Symptoms of iSGS, which develop as the subglottis becomes narrowed, may include shortness of breath upon exertion (dyspnea), hoarseness, and a high-pitched wheezing sound when breathing in or out (stridor). Stridor from iSGS is often mistaken for wheezing caused by asthma, so people with iSGS are frequently misdiagnosed, delaying a correct diagnosis. Over time, in those with iSGS, stridor and shortness of breath can progressively worsen until they are gasping for breath after simple activities or even at rest. Symptoms may also include changes to the voice, increased mucous production, and a persistent cough.
How is idiopathic subglottic stenosis diagnosed?
Doctors diagnose iSGS by ruling out other potential causes of subglottic scarring, and may use the following tests to arrive at a diagnosis:
- Pulmonary function testing: During pulmonary function testing a patient breathes into a machine called a spirometer, which measures how much air they can breathe out or take in, and can reveal reduced airflow and reduced air volume.
- Computerized tomography (CT) scan: Computed tomography (CT) is an X-ray exam that uses specialized equipment to produce cross-sectional images of parts of the body such as the neck. When viewed together these images provide a clear and detailed view of the area imaged, and can reveal a narrowed (stenotic) region.
- Endoscopy: In this test doctors use an endoscope (a small flexible tube equipped with a camera) to visualize the subglottic area of the windpipe. The endoscope is introduced through the nose and throat to the subglottic area. The rest of the trachea is evaluated as well to make sure there are no other abnormal areas. The doctor will numb the airway first so the procedure is performed comfortably, without gagging or coughing.
- Blood tests: Doctors may perform certain blood tests to look for antibodies that indicate the presence of specific autoimmune disorders known to cause subglottic stenosis.
How is idiopathic subglottic stenosis treated?
Surgery to open up the area of stenosis is the most effective treatment for iSGS. There are several surgical approaches including:
- Endoscopic incision and dilation: In this minimally invasive procedure doctors use a laser to cut the stenosis and then an inflatable balloon to dilate the narrowed area of the trachea. In many cases this procedure provides only temporary relief, and the stenosis often recurs over months to years and further treatment is required.
- Steroid injection: Often the doctor will inject the stenosis with steroids to help shrink it and decrease the risk of recurrence. This is usually done at the time of endoscopic dilation. It may also be performed alone, in the office. In this case a series of 3-4 injection are performed, each two weeks apart.
- Open surgery: In patients with severe narrowing who haven’t responded to other therapeutic options, doctors may perform open airway surgery through the front of the neck. In a procedure called a cricotracheal resection, surgeons remove a portion of cartilage from the trachea along with scar tissue, and reconstruct the affected areas. Some doctors believe that these open surgical approaches provide greater long-term results than balloon dilations or laser therapy.