Overview of Mediastinoscopy
Mediastinoscopy is used mainly as a critical procedure for diagnosis and staging how far lung cancer has spread. At the time of diagnosis, around 75% of patients who have lung cancer have either advanced local spread or spread elsewhere (metastatic disease). This highlights the need for accurate staging, which helps in planning effective treatment.
Mediastinoscopy involves creating a small cut at the bottom of the neck to insert a mediastinoscope, a device that allows doctors to directly see and take samples of the mediastinal lymph nodes; these are located between your lungs. This invasive method has a success rate of 80% to 95% in detecting cancer cells in these nodes. However, it’s not as successful (around 91% to 95%) when it comes to accessing certain lymph nodes, like those found next to the food pipe, around the aorta (main artery from the heart), and the lower part of the lung ligament.
There are 2 types of this procedure: cervical mediastinoscopy and transthoracic mediastinoscopy. Cervical mediastinoscopy is the more common procedure, which allows doctors to reach the pretracheal (near the windpipe), paratracheal (next to the windpipe), and anterior subcarinal (near the bifurcation of the trachea or windpipe) lymph nodes. Transthoracic mediastinoscopy, also called the Chamberlain procedure and anterior mediastinotomy, is a more complex procedure designed to dissect, or carefully cut away, the lymph nodes around the main artery from the heart.
The history of the surgery of the space between your lungs dates back to 1899 when an abscess, or pocket of pus, in the upper part of this area was successfully drained. However, the procedure became widely used outside Europe only in the late 1950s, with the introduction of the mediastinoscope by Eric Carlens of Sweden. This breakthrough allowed for more precise sampling of the paratracheal and hilar (near the roots of lungs) lymph nodes, greatly improving accuracy of lung cancer staging and management of illnesses related to chest cancers.
Anatomy and Physiology of Mediastinoscopy
To understand mediastinoscopy, it’s important to know about the anatomy of the mediastinum. The mediastinum is the central part in the chest, positioned between the two spaces that contain the lungs and extends from the top part of the chest cavity to the diaphragm or the muscle that sits at the bottom of the chest. In this central part of the chest, there are several crucial parts of the body including the heart, large blood vessels, windpipe, food pipe, essential nerves, the thymus gland, and lymph nodes which are small structures that produce and store cells that fight disease.
Usually, the mediastinum is split into four areas based on their positioning around the pericardium (a thin sac that surrounds the heart): top, front, middle, and back. However, a more modern way of categorizing this area, which uses clearly defined boundaries visible on a Computed Tomography (CT) scan, names the sections as prevascular (front), visceral (middle), and paravertebral (back). The prevascular or front section contains the thymus gland, lymph nodes, and a large vein on the left side. The visceral or middle section is where you’ll find various blood vessels such as the heart, the main artery in the chest, arteries within the heart’s surrounding sac, the main drainage pathway of the lymphatic system, the main vein of the upper body, the windpipe, the food pipe, and more lymph nodes. The paravertebral or back section is where the spine of the chest and nearby soft tissue can be found.
Why do People Need Mediastinoscopy
A mediastinoscopy is a medical procedure that doctors use mainly for three reasons:
1. To check if lung cancer has spread to the lymph nodes. The lymph nodes are small, bean-shaped glands that produce and store cells that fight infection.
2. To take a small piece of tissue (biopsy) from potentially cancerous tumours to examine under a microscope.
3. To remove abnormal growths and enlarged lymph nodes from the mediastinum (the space between the lungs).
This procedure helps doctors access various groups of lymph nodes located in the mediastinum, near the bronchi (airways leading into the lungs), and below the windpipe. It’s crucial for diagnosing conditions that may present with masses in the mediastinum.
Conditions that could cause these masses include tuberculosis (an infectious disease that primarily affects the lungs), sarcoidosis (inflammation that produces tiny clumps of cells in different parts of your body), histoplasmosis (an infection caused by breathing in spores of a fungus), coccidioidomycosis (a type of fungal lung infection), and different types of cancers and tumours including lymphomas, thyroid and parathyroid tumours, oesophageal and neurogenic tumours, and germ cell tumours.
On top of diagnosing these conditions, mediastinoscopy is also vital in managing lung cancer by providing tissue for diagnosing and staging the disease, which is necessary when figuring out the best treatment. There might also be vascular conditions that present with a mass in the mediastinum such as aneurysms (a bulge in the wall of an artery) and aberrant vessels (blood vessels that have developed abnormally). Also, benign conditions like cysts could cause a mediastinal mass.
All these conditions should be considered when a mediastinal mass is detected in a patient, even though they might not require a mediastinoscopy for diagnosis or treatment.
When a Person Should Avoid Mediastinoscopy
In some cases, a person cannot undergo a medical procedure known as a mediastinoscopy due to certain conditions, or contraindications. There are two main types: absolute and relative contraindications.
Absolute contraindications are situations where the procedure must not be performed. These include:
– A lump or mass in the area at the center of the chest (anterior mediastinal mass)
– A tumor that cannot be removed (inoperable tumor)
– Previous damage to the laryngeal nerve, a nerve in your throat that sometimes gets injured during surgery
– People who are extremely weak or very unwell
– An aneurysm (a bulging, weak spot) on the ascending aorta, which is the large blood vessel branching off the heart
– People who’ve had a mediastinoscopy previously, because the scar tissue from that procedure can make it too dangerous to do again.
Relative contraindications are situations where the risks and benefits must be carefully weighed. These include:
– Blockage of the area at the top of the chest (thoracic inlet obstruction)
– SVC syndrome, a group of symptoms caused by the obstruction of the superior vena cava, a large vein carrying blood into the heart
– Severe shifting of the windpipe from its usual position (tracheal deviation)
– Having previously received radiation therapy to the chest
Anything that changes the usual structure of the body, like any of the above conditions, increases the chance of injury to blood vessels or airways. This can be extremely dangerous in this part of the body.
Equipment used for Mediastinoscopy
To carry out a mediastinoscopy, which is a procedure to examine the area in the middle of your chest (between your lungs), we will need some special tools:
- A mediastinoscope – this is a long, thin tube with a light and a camera at the end that helps doctors see inside your chest.
- A fiberoptic light cable – this is a flexible, light carrying wire that is used to light up the inside of your body during the procedure.
- Biopsy forceps – these are special instruments used to remove a small sample of tissue for further testing.
If we are undergoing the procedure with you asleep under general anesthesia, we’ll also need an anesthesia machine. This is a machine that controls and monitors the delivery, of drugs that make you sleep and prevent pain, to keep you comfortable during the surgery.
Furthermore, we always have a cardiothoracic setup on standby just in case there is a need for more specialized heart and lung tools and equipment. This is just a precautionary step and nothing to worry about – we always have a full range of equipment prepared to manage any situation that may come up in surgery.
Who is needed to perform Mediastinoscopy?
Mediastinoscopy is a complicated surgery. It has several important parts and needs a team of doctors and healthcare workers to work together to make sure it goes well. Here are the team members you might meet:
A surgeon: This person is a doctor who specializes in heart and lung surgeries, or in general surgery. They have special training in doing mediastinoscopy. One of their important jobs is to be ready to deal with any problems that might come up during the mediastinoscopy. This can include doing an emergency surgery like a thoracotomy (opening up the chest) or a sternotomy (making a cut down the middle of the chest).
An anesthesiologist: This is a doctor who will give you medicine so you’ll sleep through the surgery. They also keep an eye on your heart rate, blood pressure, breathing, and other important signs of your health. They make sure you stay safe during the surgery.
Operating room support staff: These are the nurses and technicians who help the surgeon. They get the operating room ready, make sure all the surgical tools are clean and ready to use, and give help during the surgery.
A pathologist: This is a doctor who looks at the tissue that’s taken out during the mediastinoscopy. They study it under a microscope to see if there are any diseases or cancer. This helps your doctors decide on the best treatment for you.
Laboratory personnel: These are people who work in the lab. They run tests on the tissue from the biopsy to figure out specific details about any cancer cells. This information helps your doctors plan the best treatment for your particular type of cancer.
Preparing for Mediastinoscopy
Before a medical procedure called a mediastinoscopy, where a viewing device is inserted into the chest to closely inspect the structures in the area between the lungs (the mediastinum), a patient will go through several steps to help prepare them and doctors for surgery. These steps help to check the patient’s health and reduce their risk of complications. If a patient has chest-related symptoms, such as trouble breathing, feeling short of breath when lying flat, or wheezing, the doctors will be especially thorough in checking them over, as these could suggest a mass causing blockage in the mediastinum.
The preparation for the procedure includes several important check-ups:
- X-rays to see an overall picture of the chest.
- A CT scan is carried out to look at detailed and specific images of the mediastinal area, which is the space between your lungs.
- Pulmonary function tests are done to assess the health of the lungs and ascertain the capacity to breathe properly.
Patients who could have a mass impeding their airways should have these pulmonary function tests done in two positions – sitting up and lying down. The results of these tests help doctors figure out if the mass is outside the chest cavity (extrathoracic) or inside the chest cavity (intrathoracic).
Other diagnostic tests are done if the windpipe appears to be pushed aside, signifying the presence of a mass. These tests help locate the mass in the chest and measure how it’s affecting the patient’s airways.
To maintain safety during the procedure, an intravenous (IV) line is established to administer necessary fluids and medications directly into the bloodstream. If the patient’s upper body shows signs of swelling due to a large mass blocking a major vein called the superior vena cava (SVC syndrome), the IV line will be placed in the lower body to ensure smooth circulation.
A mediastinoscopy can be performed under local or general anesthesia – which numbs the body or puts it to sleep, respectively. However, general anesthesia is commonly preferred unless the patient has signs of airway blockage before the procedure. In this case, they may be kept awake but comfortable while a flexible tube is inserted for breathing.
After the patient has been settled for the operation with all the tubes and lines in place, the chest is prepared in case a larger incision (a median sternotomy) is needed because of heavy bleeding during the procedure.
Patients with a large mass in the front of the mediastinum need extra attention and preparation, as this mass can cause difficulty in lying flat and can even block their airways. Even after a successful intubation (placing a breathing tube), the mass can interfere with the airways further down when the muscles are relaxed, causing serious complications. Hence, specially trained doctors (otorhinolaryngologists) assist with this procedure and a heart-lung bypass machine is kept on standby in case of emergencies. Careful preparations and consideration of all possible complications can make the procedure of mediastinoscopy safer for patients.
How is Mediastinoscopy performed
A procedure known as ‘mediastinoscopy’ is normally performed in an operating room and you will be fully asleep due to a type of medication called general anesthesia. It’s used to examine the area between your lungs, unless you have a particular mass at the front part of this area that could affect your breathing when you lie flat. In such cases, another position may be used to ensure your safety.
During a typical mediastinoscopy, after you’re asleep, we turn and tilt your head to one side. Then, we make a small cut (about 1.2 inches long) just above the dimple in your neck. This dimple is known as the suprasternal notch, and it’s located between the two large muscles of the neck, known as the sternocleidomastoid muscles.
From this point, we carefully separate different layers of your neck tissue until we reach the trachea, which is the tube that allows air travel to and from your lungs. We keep creating a path towards the space between your lungs, which is known as the superior mediastinum.
Once we have created this path, we insert a special device called a ‘mediastinoscope’, which is essentially a thin tube with a light and a lens that helps us see clearly inside your chest. This mediastinoscope allows us to examine and take samples from lymph nodes, which are small glands that make and store cells that fight infection, and masses that might be present within this upper part of the space between your lungs.
Possible Complications of Mediastinoscopy
Having a mediastinoscopy, a procedure where a slim instrument is inserted into your chest to examine the area between your lungs, is generally considered safe. However, some people might experience problems — around 1.5% to 3% have less-than-ideal outcomes and around 0.09% of the cases lead to death. The problems can range from minor to severe.
Some of the main issues can include:
– Bleeding: There can be two types of bleeding – minor and major
– Minor bleeding can happen at the place where the incision was made or when a tissue sample is taken. Usually, this can be controlled by applying pressure or carrying out minor procedures.
– Major bleeding can occur if larger blood vessels are injured, such as the innominate artery, aorta, or lungs’ arteries. This condition might warrant immediate medical intervention, up to and including surgery to fix the damaged tissue.
– Infection: This can also occur in two ways –
– Wound infection can happen at the surgery site, requiring antibiotics or potentially another surgery to drain the infection.
– Mediastinitis is a rare infection that can happen inside the chest cavity, requiring aggressive antibiotic treatment and potentially another surgery.
– Pneumothorax: This is when a lung collapses after mistakenly entering the space around the lungs. If this happens, a chest tube might be required to help the lung re-inflate.
– Tracheal or esophageal injury: Injuries can occur resulting in a hole in either the trachea (windpipe) or the esophagus (tube that carries food from the mouth to the stomach). This might cause air leaks, chest infections, and require another surgery to repair the damage.
– Recurrent laryngeal nerve injury: Damage to a nerve in the neck can cause vocal cord paralysis, hoarseness, or difficulties with breathing. These symptoms could either be short-lived or permanent.
– Vascular compression: Major blood vessels can be compressed, reducing blood flow to the brain, potentially causing neurological symptoms and stroke.
– Air embolism: Entry of air into the blood vessels during surgical procedures which can result in a rare but potentially fatal complication.
– Chylothorax: Injury to a duct in the chest can cause fat and protein-rich fluid to leak into the chest cavity. This could require changes to diet, drainage, and potentially another surgery to fix the problem.
– Anesthesia-related complications: As with any procedure that requires general anesthesia, complications such as adverse reactions to the anesthesia, slowed down breathing, and instability of the heart and blood vessels can occur.
Given these possible complications, mediastinoscopy should be performed by experienced surgeons in a well-equipped operating room, with proper assessment before surgery and close monitoring during surgery to minimize risks.
What Else Should I Know About Mediastinoscopy?
The mediastinum is the space in your chest between your lungs. A procedure called mediastinoscopy helps doctors examine this area and evaluate the nearby lymph nodes, particularly when diagnosing lung diseases like bronchogenic carcinoma (a type of lung cancer). This procedure is vital for categorizing non–small cell lung cancer, one of the most common types of lung cancer.
Another related procedure to mediastinoscopy is the endobronchial ultrasound-guided (EBUS) fine-needle aspiration (FNA). EBUS takes pictures of your lungs and the surrounding area using a minor procedure that retrieves tissue samples. When diagnosing non-small cell lung cancer, patients usually have an EBUS biopsy before treatment, followed by mediastinoscopy after treatment.
Video-assisted mediastinoscopy is a newer technological advancement that helps doctors see the chest area better and use more tools during the procedure. Even with the rise of EBUS biopsies, mediastinoscopy remains crucial in diagnosing nodal metastases (spread of cancer to the lymph nodes).
It’s vital for patients and healthcare staff to fully understand this procedure due to its link to lung cancer diagnoses. Being well-informed could improve patients’ outcomes. Studies suggest we’ll see an increase in the number of these procedures and that mediastinoscopy is slightly less expensive than an EBUS biopsy.
