Idiopathic Subglottic Stenosis (ISS)
Idiopathic means "of unknown cause," and subglottic refers to the part of the airway located immediately below the vocal cords. Stenosis refers to narrowing, usually due to scar tissue. Idiopathic subglottic stenosis (ISS), therefore, refers to a narrowing of the part of the airway located immediately below the vocal cords for unknown reasons. The condition is rare, but afflicts pre-menopausal women significantly more often than men and is believed to be due to an autoimmune inflammatory response that causes scar tissue to build up at the bottom of the voice box, below the vocal folds and just above the trachea.
At Mount Sinai’s Department of Otolaryngology – Head and Neck Surgery, our physicians have specialized expertise in diagnosing and treating this sensitive area of the throat. The management principles for ISS have evolved over the last decade. Surgery is no longer the first treatment option. Our physicians have vast experience with in-office transcutaneous injections of steroid, which reduce the inflammatory process that creates stenosis leading to symptoms of difficulty breathing. Patients are treated in the office the same day and usually notice reduction of symptoms within a week of the first treatment.
Symptoms of ISS
The most common symptoms of idiopathic subglottic stenosis are:
- Shortness of breath with activity. For this reason, nearly one third of patients with ISS are misdiagnosed as having asthma. Therefore, if adult patients present with new onset reactive airway disease, they should be screened for ISS, particularly if their symptoms are not relieved by treatment for asthma.
- Stridor, a high-pitched musical sound that can be heard as the breath is drawn in and out, and is caused by a blockage in the throat or voice box (larynx).
- Voice changes or increased vocal roughness.
Diagnosis of ISS
The diagnosis of idiopathic subglottic stenosis is made by examining the voice box and upper windpipe. Most otolaryngologists can perform an examination of the subglottic airway in the office without the need for sedation. A mirror, rod-lens telescope or a flexible telescope can be placed in the patients’ mouth or nose respectively. Specialized otolaryngologists (laryngologists) will often videotape the examination and review it with you. This allows visualization of the lower portion of the larynx. The scar tissue is visualized and as long as there was no history of prior intubation or trauma, then the cause is presumed to be idiopathic.
Treatment of ISS
When patients are initially suspected to have ISS, because they have stenosis, and are female with no prior history of laryngeal trauma or intubation, a tissue biopsy should be performed to be certain no other disease process is involved. ISS is a diagnosis of exclusion. Once the diagnosis is confirmed, then treatment options may include:
- Endoscopic dilation with or without incisional techniques and steroid injection: This procedure provides immediate relief of symptoms and is performed as an outpatient procedure through the patient’s mouth, but requires general anesthesia. There are no incisions on the neck. A laser or a knife can be used to incise the area prior to dilating it with a balloon or rigid bronchoscope. The theoretical purpose of the incision is to reduce the trauma from dilation. However, surgical techniques vary and, a systematic review published in JAMA Otolaryngology found that no one technique is associated with a better outcome. Patients in general require repeat procedure every 9 to 12 months and have minimal downtime. They can be released from the hospital the same day and often return to regular activities the next day feeling and breathing better.
- In-office transcutaneous steroid injections: these are performed in patients who can breathe adequately enough to tolerate some airway swelling from the procedure itself. Under local anesthesia applied to the nose, trachea and skin of the neck, a flexible laryngoscope is placed through the patient’s nose to visualize the subglottis. Then a needle is placed through the skin of the neck into the airway. Steroid is then injected directly into the inflamed area. This usually requires a series of 3 injection spaced 4 to 6 weeks apart. But the patients on average achieve a year or more of symptom remission before needing repeat injections.
- The Maddern Procedure: a relatively new endoscopic procedure, this entails the scar removal and placement of a split thickness skin graft from the thigh. The theory is that this will prevent the inflammatory process from reoccurring. However, this is a theory and the longevity of the procedure has not been studied thoroughly. Therefore, the procedure is only recommended for patients who do not have success with either steroid injection or incision and dilation.
- Cricotracheal resection (CTR) with primary reconstruction: during this procedure the surgeon removes the constricted section of the windpipe and rejoins the ends. This is much more difficult than a standard tracheal resection as the framework of the subglottis contributes substantially to the stability of the airway. In addition, the muscles and nerves that control the vocal folds are very near in proximity. Some of the muscles that help elevate pitch are removed during the operation so the voice after is always softer and lower in pitch. CTR has been done mostly in patients who have inflammation that is difficult to control or who have had complications from prior endoscopic surgery. The patient satisfaction rate with the procedure, trade off in voice versus airway is roughly 75%. There is a 5 to 18% failure of the surgery in which patients can be worse after or require a tracheotomy to maintain their airway. Recurrence of ISS has been reported more than 5 years after CTR surgery.
Mount Sinai Expertise with ISS
In the Department of Otolaryngology-Head and Neck Surgery at Mount Sinai, we offer all of these interventions. After discussion with the patient we tailor our interventions to their needs. These needs may change over the years. ISS is a chronic condition for which we do not know the cause. Therefore, patients should establish a long relationship with a physician they trust. They can follow the course of their disease together with the surgeon and be involved in management options. It is our experience that the disease frequently goes into remission somewhere between 5 and 10 years after symptom onset and rarely returns. It is our goal to manage your symptoms with as minimal intervention as possible throughout this journey.