Overview of Laryngeal and Tracheal Stents
Laryngeal and tracheal stenosis are less common conditions but may cause severe difficulties with breathing. Laryngeal stenosis is the narrowing of the different parts of the larynx, which includes the area above the vocal cords (supraglottis), the vocal cords themselves (glottis), or the area below the vocal cords (subglottis). Tracheal stenosis is the narrowing of the trachea, or windpipe, from below the subglottis to the split in the trachea leading to the lungs. Bronchial stenosis is the narrowing of the tubes (bronchi) that lead from the trachea to other parts of the lungs.
Even though laryngeal and tracheal stenosis may seem similar, it’s critical to differentiate them as their long-term treatment and outcomes can vary quite a bit. Both conditions, however, can potentially be treated through stenting, which helps open up the airway, whether these conditions are present from birth or developed later in life.
Amongst congenital (born with) conditions, laryngeal stenosis, particularly in the subglottis, is the third most common after laryngomalacia and congenital vocal fold palsy. Interestingly, it is adult women who more commonly acquire laryngeal stenosis and the exact reason is unknown. Stenosis (narrowing) of the airway after intubation (insertion of a tube through the mouth into the airway) is a significant problem, presenting as either laryngeal stenosis, tracheal stenosis, or both. Other causes for narrowing of the larynx and trachea can include chemical injury, infections, tumors, or granulomatous disease (a type of inflammation).
The treatment for laryngeal and tracheal stenosis isn’t universally standardized. Rather, treatments are customized for each patient based on the cause and location of stenosis within the airway. Several treatment options include enlarging the airway endoscopically, using laryngeal microsurgery, excising with a laser, performing open airway surgery, or placing an endoscopic stent.
A laryngeal or tracheal stent, made from solid or hollow materials, can be used to help keep the airway from collapsing. These stents can also support surgical restorations of the larynx or trachea and mechanically widen areas affected by scar tissue or tumor growth. The stents can be either absorbable (body can break them down) or nonabsorbable, and can be made in different sizes and shapes to fit the patient’s specific condition. Recently, there have been developments in the use of external tracheal suspension devices.
Anatomy and Physiology of Laryngeal and Tracheal Stents
The larynx, also known as your voice box, is located above your windpipe (trachea) and below a small U-shaped bone in your neck called the hyoid bone. It’s a complex structure made up of nine different types of cartilage, including the thyroid and cricoid cartilages, the epiglottis, and pairs of arytenoid, cuneiform, and corniculate cartilages. The larynx has a couple of important roles: it controls the flow of air in and out of your lungs, and it also helps you speak by providing a place for your vocal cords to vibrate.
One important job of the larynx is to prevent food and water from going into your lungs. However, certain medical treatments, like the use of stents to help keep the airway open, can interfere with this protective function by preventing the larynx or glottis (the space between your vocal cords) from closing properly.
Moving down to the trachea or your windpipe, it’s a tube-like structure located below the larynx. It’s made up of 16 to 20 cartilaginous rings and a muscle on the back that shares a wall with the food pipe (esophagus). The trachea’s key job is to get air to and from your lungs, and it’s built to stay open even when you’re breathing in sharply. However, things like swelling, damage to cartilage, or external pressure can cause the trachea to narrow. When this happens, air has to move faster through the smaller space, and it takes more pressure to keep the air moving.
When doctors diagnose a narrowing of the larynx and trachea, they use a grading system, called the Cotton-Myer subglottic stenosis grading scale, to measure how serious the obstruction is. This scale ranges from grade I (0%-50% blockage) to grade IV (complete blockage).
In 1992, a doctor named McCaffrey came up with another way to classify this condition. He uses a grading system to describe the length of the stenosis (narrowing) and which parts of the throat are affected: the vocal cords (glottis), the area below the vocal cords (subglottis), and the windpipe (trachea). The stages range from I (a small area of narrowing in the subglottis or the trachea) to IV (narrowing that includes the glottis and causes a vocal cord to become fixed or paralyzed).
Why do People Need Laryngeal and Tracheal Stents
There are many health issues, both inherited and developed, where it might be necessary to use devices known as laryngeal and tracheal stents. These devices may be needed for a variety of situations like:
– The rebuild of a narrowed larynx or windpipe (a condition known as laryngotracheal stenosis)
– Injuries to the throat or windpipe
– A birth defect causing narrowing of the larynx or windpipe
– Cancer that has spread to the windpipe or bronchial tubes
– A birth defect where the larynx doesn’t develop properly (known as laryngeal atresia)
– Softening of the windpipe’s walls or bronchial tubes, which can cause them to collapse (tracheomalacia or bronchomalacia).
When a Person Should Avoid Laryngeal and Tracheal Stents
There are some cases where placing a stent in the voice box or windpipe isn’t possible. These include:
People who can’t have general anesthesia, which is a medication that puts you to sleep during the procedure.
People who are allergic to the material the stent is made from.
People who don’t have enough healthy lung tissue below where the obstruction is located. This is necessary to ensure the lung can properly expand after the stent is placed.
Equipment used for Laryngeal and Tracheal Stents
In simple terms, laryngotracheal stents are medical devices that doctors place in your throat to help you breathe easier. They are usually used for situations where there is a disease affecting the voice box area (the larynx) or the windpipe (the trachea). Doctors categorize these stents as either suprastomal or substomal/intratracheal based on where in your throat they are placed.
Suprastomal stents are used for diseases in the upper part of the trachea, the region just below the voice box (larynx); these are often related to issues in the voice box. Substomal/intratracheal stents, on the other hand, are placed lower in the windpipe or when the disease is specific to the windpipe. Depending on the specific disease being treated, these stents can be placed using either a minimally invasive method (endoscopic) or an open surgery approach. There are different types of materials used to make these stents, and they can be designed for short-term or long-term use (less than six weeks or more), depending on the type of material and the needs of the patient.
There are a multitude of stents available today because of the versatility these options provide, allowing for tailored solutions to specific patient needs. Here are a few of them:
Montgomery T-tube was introduced in the 1960s and is made from a soft material called silicone that minimizes irritation but can affect the removal of mucus from the airway. This tube is inserted through an opening made in the neck and is used to assist with breathing and suctioning while in place.
The Aboulker stent, popular in the 1980s, had a rigid structure and differed from the Montgomery T-tube due to its lack of an additional lumen (tube). However, the migration of this solid, rigid stent above the artificial opening in the neck created considerable concern. The Aboulker stent is not available in the United States now, giving way to the Rutter, Monnier stents, and the continued use of the Montgomery T-tube.
The Rutter stent, made of a soft silicone material with tapered ends, can be added through both open and minimally invasive means without impacting the addition of a breathing tube. It is designed to minimize irritation and tissue overgrowth. However, due to its cap, it almost always necessitates a tracheostomy (a surgical opening into the windpipe).
The Monnier stent, also made of soft silicone and available in numerous sizes, is based on the structure of the human voice box. It is particularly useful for certain forms of throat narrowing and contributes to patient comfort by reducing the formation of excessive tissue at pressure points.
Silastic sheets were first introduced in the 1970s, and whilst they were originally used as soft stents and later for cases of narrowing of the anterior voice box, they often caused irritation due to their sharp edges. Nowadays they can still be used in a minimally invasive surgery to repair the windpipe from the inside.
While silicone stents like the Dumon and Hood are commonly known for their softer material and lesser propensity to form granulation tissue, they have one major problem, they can move from their place. Endotracheal tubes are used for short-term stenting after major surgery for disorders involving the windpipe and the voice box. However, their use for longer-term stenting is often limited to emergency situations. Lastly, metallic stents, although efficient, may lead to the formation of excessive tissue at their ends. These stents often incorporate themselves into the windpipe and are considered by some as permanent.
Metallic stents must be used temporarily and with caution in children, as the possible problems can be similar to or worse than their underlying breathing issues. The Food and Drug Administration (FDA) has issued a warning about using such stents for non-cancerous airway diseases in children. Silicone-coated metallic stents have been developed to alleviate some of these problems, but they still have bare wire at their ends to help the stent stay in the windpipe.
Preparing for Laryngeal and Tracheal Stents
Doctors use a combination of tools to assess your airways: laryngoscopy (inspecting the throat), bronchoscopy (examining the breathing tubes), and in some cases, imaging studies (pictures from inside your body) like a CAT scan or MRI. These are used when a simple examination isn’t enough to fully understand a problem area or lesion (an area of the body where the tissue is damaged).
Identifying exactly where the blockage or lesion is important. It could be in different parts of the voice box, or in the windpipe or bronchial tubes (tubes that carry air in the lungs). Doctors also need to know how far the problem area is from key landmarks inside your throat.
There are several ways to understand how serious the stenosis (narrowing of the space in your airway) is. The Cotton-Myer system is one method, or doctors may estimate what percentage of the airway is blocked and note down how long the narrowed area is.
In situations where it’s tough to measure the blockage accurately with an endoscope (a thin tube used to look inside your body), doctors might use a CAT scan for precise measurements.
The severity, length, and location of the stenosis in your throat or windpipe inform the choice of stent (a tiny tube doctors put in your body to keep a passage open) and whether to opt for open or endoscopic surgery (surgery performed with special tools and a camera, so doctors don’t have to make large cuts in your body).
This is when other medical experts, like lung specialists and heart-and-lung surgeons, come in handy. They can give valuable input and help create the best surgical plan for your condition.
How is Laryngeal and Tracheal Stents performed
Medical specialists place stents in the windpipe (tracheal) and voice box (laryngeal) to treat certain diseases. These stents can be inserted through different techniques like endoscopic (via a tube with a camera), open surgery, or a mix of both. The type of procedure used depends on the patient’s condition, the disease involved, and the surgeon’s preference and experience.
Laryngeal Stents:
Laryngeal stents, which keep the airway open and hold any reconstructive devices in place, are not typically the main treatment for narrowing of the voice box (laryngeal stenosis). They are often used temporarily after surgery. This is different from the trachea, where stents are frequently used as the primary treatment.
For the endoscopic approach, which is commonly used, the patient is positioned lying on their back with a roll under the shoulders to stretch out the neck. It’s important to prepare the area of the neck being treated in a sterile manner and have a plan for administering anesthesia. The surgeon will then use special instruments and a camera to locate and treat the laryngeal stenosis. The stent is inserted and secured using sutures or threads.
In the open approach, the surgical team will open the patient’s larynx and place the stent after treating the laryngeal stenosis. The larynx is then closed over the stent. Sometimes, a combined approach of endoscopic and open surgery is used.
Tracheal Stents:
Tracheal stents can be used for both short-term and long-term purposes. They are usually placed using a bronchoscopic (camera) approach, but sometimes open surgery is needed, although it is increasingly rare.
In the bronchoscopic approach, the process is completed under general anesthesia, and a bronchoscope is used to visualize the airway, confirm the lesion’s location, and assess its severity. Following this, the narrowed airway is widened using a small balloon or tumor removal (debulking) when a tumor is involved. A thin flexible wire is placed through the stenosis to guide the stent. The stent is then deployed, and once confirmed its in the right place, it takes 24 to 48 hours for the stent to fully expand.
Open techniques for tracheal stent placement are rarely used today. However, there is a growing interest in the open approach for tracheal transplantation and other procedures for tracheobronchial replacements or reconstructions.
Possible Complications of Laryngeal and Tracheal Stents
Laryngeal stents, which may be used to treat breathing problems or other conditions that affect the larynx (the voice box), come with some risks. Issues can include the growth of granulation tissue (a type of tissue that may develop during the healing process) at the edges of the stents, which can occur in up to 80% of cases. The stent might move out of place or even be inhaled accidentally. It can also get blocked by mucus, or become infected, commonly by bacteria such as Staphylococcus aureus or Pseudomonas aeruginosa. Another possible issue is that the stenosis, or narrowing of the airway, could come back after the stent has been removed. This happens in 40%-80% of cases. Difficulty swallowing or inhaling foreign substances may also occur.
The same kind of problems can arise with tracheal stents, which are used to treat conditions that affect your airway or trachea. Again, the most common issues are the stent moving out of place or granulation tissue growth, which can lead to the airway getting narrow again. Another possible side effect is tracheoesophageal fistula, a rare condition where an abnormal connection forms between the airway and the esophagus. If the stent was initially placed to treat this issue, there’s a chance of up to a 39% recurrence rate. Another serious but rare complication is a hole forming between the trachea and the nearby large artery in the chest (a tracheoinnominate fistula). Yet, more problems could be the stent getting blocked by secretions, or even breaking, which happens in about 10% of cases.
What Else Should I Know About Laryngeal and Tracheal Stents?
Laryngeal (voice box) and tracheal (windpipe) stents are types of tiny mesh tube supports that doctors use to keep the airway open after surgery. These stents are often used after reconstructive surgery that involves this area. Tracheal stents, in particular, are generally used in end-of-life care to help people who have severe airway diseases or tumors that are affecting their ability to breathe properly. Doctors specializing in lung-related treatments or heart and chest surgeons usually handle the placement of these stents.
As of now, there aren’t any set rules about the best kind or characteristics of stents to use in these situations. The choice of the stent material and type gets determined on a case-by-case basis, depending on each patient’s unique health situation. Scientists are still researching to design the perfect stent—one that can stay open properly, comes in different sizes, can stretch as needed, limits problems, and doesn’t overly irritate the surrounding tissues.