Overview of Substernal Thyroidectomy
The surgery performed for treating retrosternal goiters, an abnormal enlargement of your thyroid that develops behind your breastbone, is called a substernal thyroidectomy. Retrosternal goiters, also known as intrathoracic, substernal, or mediastinal goiters, are very specific types of thyroid goiters. They are identified as those thyroid abnormalities where more than half of the enlarged thyroid is located beneath the entry point of your chest and extends into a central area of your chest called the mediastinum.
But, different medical professionals use different definitions, and so, there isn’t a definite agreement on how frequently these types of goiters occur. Some studies show that they can be as rare as occurring in only 2 out of 1000 goiters, while others demonstrate that almost half of all goiters could be retrosternal.
Mostly, the majority of these enlarged thyroid masses are made up of benign (non-cancerous) lumps and carry no threat. However, it’s also possible that the portion of the gland that’s growing beneath the breastbone could be cancerous. Oftentimes these thyroid masses don’t cause any issues and may even be found unexpectedly during a medical scan for something else. But in some cases, due to the mass pressing against your windpipe, large blood vessels, or food pipe, the condition could cause discomfort in your neck.
This thyroid mass often grows towards the front and top portion of the mediastinum and usually extends further into one side of the chest. Sometimes, this mass can even grow towards the back of the mediastinum. Medical professionals generally agree that treatment methods like suppressing the thyroid hormones or using radioactive iodine are not suitable for these types of goiters. Instead, surgery is considered the best way to manage retrosternal goiters.
The surgical procedure to remove this thyroid mass could be either through the neck (transcervical), where a cut is made in the neck, or through other parts of your body (extracervical). Several surgical methods have been elaborated, which we’ll discuss more in this article. However, the medical community hasn’t yet reached a unanimous agreement on when exactly surgery should be recommended for substernal thyroid goiters.
Anatomy and Physiology of Substernal Thyroidectomy
Goiters are abnormal enlargements of the thyroid gland, a butterfly-shaped gland located in the throat. Specifically, intrathoracic goiters are ones that grow inside the chest area. There are two main types of these. The most common type, called acquired goiters, start in the thyroid gland and then grow, either quickly or over many years, down from the throat into the chest cavity. The other, much rarer type, called truly intrathoracic or aberrant goiters, grow from thyroid tissue that was misplaced in the chest region before a person was born.
Most intrathoracic goiters can be found in the upper part of the chest, in front of the vessels leading to the arms. Only a small percentage (10-15%) grow behind the windpipe, while an even smaller group ends up positioned behind the esophagus, the tube leading to the stomach.
Due to different definitions of intrathoracic goiters, in 2008 Huins and colleagues came up with a classification that doctors use today. This depends on where the goiter has expanded to. They divided it into three grades: Grade 1 includes thyroid tissue located above the main artery leading from the heart. Grade 2 includes tissue between the main artery and the fluid-filled sac that surrounds the heart, while Grade 3 includes tissue that extends to the right side of the heart.
These grades help doctors make the best plans for surgery based on the individual patient’s situation.
Why do People Need Substernal Thyroidectomy
A multinodular goiter is when your thyroid gland, located in your neck, grows uneven lumps or nodules. There are three main reasons a doctor might choose to surgically remove these lumps:
- The lumps may be cancerous or suspected to be cancerous
- The lumps are so large they are pressing on other organs in your neck
- For aesthetic reasons—for instance, if the lumps are very visible and are causing distress
Doctors prefer to remove the goiter, even if it’s currently not causing any symptoms, because these lumps can keep growing. As they get larger, they become more difficult to remove and can even start to press on important areas in your neck, such as your windpipe, food pipe, and a large vein called the superior vena cava. This is especially a concern if the goiter grows downwards into your chest—a condition called a substernal goiter.
When dealing with substernal goiters that are causing symptoms, there are several factors to take into account in deciding the best course of action:
- The lumps tend to grow larger over time
- If the lumps are not removed, the option of treating with a form of radiotherapy called radioiodine could increase their size, causing complications
- Cancer might be present in up to one-quarter of these goiters
- In most cases, substernal goiters can be removed through neck surgery
If you have a substernal goiter that isn’t causing any symptoms and you have normal breathing tests, surgery might not be necessary and a watch-and-wait approach could be recommended. However, if the goiter is suspected to be cancerous, or if patients are young and healthy (since the goiters can grow and have a high risk of being cancerous), surgery is typically recommended. Older or unwell patients might be recommended for observation or radioiodine treatment.
Your doctor might also perform a simple test, called a Pemberton sign, by having you raise your arms above your head. If this causes your face or neck veins to swell, or causes wheezing because your windpipe is blocked, surgery is typically recommended.
In terms of how to approach the surgery, there are different options depending on the specifics of the goiter. Surgery can be performed through your neck or chest, and the exact strategy will depend on details like the size and location of the goiter and whether the cancer has spread locally. Various scans can help the doctor decide on the best approach.
Using multiple angles from the computerised tomography (CT) scan, doctors can decide the most suitable surgical strategy. For instance, signs of cancer and calcification of the thyroid capsule—which could make it difficult to remove the lump—might mean a chest surgery is needed.
A grading system can also help the doctor decide the best surgical approach based on the characteristics of the goiter. Smaller substernal goiters might be removed through neck surgery, while larger or more complicated goiters might require chest surgery.
When a Person Should Avoid Substernal Thyroidectomy
The treatment for intrathoracic goiters, which are enlarged thyroid glands located inside the chest, should be personalized for each patient. Several aspects need to be considered in planning treatment. These include how the condition is affecting the patient (clinical presentation), the size of the enlarged gland and how fast it’s getting bigger, and any heart or lung diseases the patient might have.
In some cases, a high-risk patient may not be able to handle full anesthesia. Anesthesia is a medicine that makes you sleep deeply and not feel pain during a operation. If a patient can’t tolerate this, then having a surgery to remove the enlarged thyroid gland below the breastbone (substernal thyroidectomy) isn’t safe.
In such circumstances, doctors often lean towards non-surgical treatment options. These can include monitor and managing the symptoms conservatively (without surgery), or a treatment called radioiodine. During a radioiodine treatment, a patient takes radioactive iodine by mouth, which travels to the thyroid and slowly shrinks the gland.
Equipment used for Substernal Thyroidectomy
To perform a substernal thyroidectomy, a type of surgery that removes part or all of your thyroid gland located in your neck, the surgeon will need several specific tools and facilities:
* A fully-equipped operating room for performing surgeries
* Clean and sterile drapes, gowns, and gloves to prevent infection
* Specific surgical instruments like sutures (thread used for stitching), vessel loops (used to control blood flow during the surgery), and bone wax (used to stop bone from bleeding)
* A sternotomy saw, a special type of saw used to cut through the breastbone
* A code cart, which is a set of drawers on wheels that contains medicines, equipment, and supplies needed in case of a medical emergency
* Anesthesia to numb the area and prevent pain during the surgery
* A shoulder roll, a special pillow used to position your head and neck during the surgery
* A laryngeal nerve monitoring system, used to watch and protect the nerves in your neck that control your voice box and vocal cords during the surgery
* An NG or nasal gastric tube, a tube that is put through your nose into your stomach to drain fluid and air out during or after the surgery.
Who is needed to perform Substernal Thyroidectomy?
A number of different medical professionals are needed to perform a special type of surgery known as a substernal thyroidectomy. This operation involves the removal of a part of the thyroid gland, a small organ located in your neck, which has grown into your chest.
These specialists include a specialized surgeon who might be an expert in ear, nose, and throat surgery, chest (thoracic) surgery, or hormone (endocrine) system surgery. These surgeons have the necessary skills to safely conduct this specific operation.
An anesthesia team is also involved. They make sure you’re comfortable and pain-free during the surgery. They’re responsible for putting you to sleep (placing you under anesthesia) for the procedure, and monitoring you while you’re asleep to make sure everything is okay.
A surgical first assistant is another crucial member of the team. This professional helps the surgeon during the operation. They may help to hold instruments and perform parts of the surgery under the surgeon’s guidance.
The nursing staff in the operation room, along with scrub techs (people trained to assist in surgeries) also play important roles. They make sure all instruments are sterilized and ready, and help before, during, and after the operation.
Additionally, specialists in oncology (cancer care), internal medicine (general health care), and endocrinology (hormone-related disorders) also may be involved in your care. They can help manage any related health issues before and after the operation and offer their specialized knowledge. They are all there to help you get through the surgery safely.
Preparing for Substernal Thyroidectomy
If a doctor suspects that a patient may have a goiter (an abnormal enlargement of the thyroid gland) located within the chest cavity, the patient would have to go through several diagnostic procedures. The medical team will ask the patient a series of questions to get a full understanding of their medical history. They’ll also examine the patient physically, conduct tests to check the thyroid function, and search for the presence of certain antibodies in the blood.
Before the doctors can perform a substernal thyroidectomy (surgery to remove the goiter), they must evaluate the patient’s airway and voice box status. They would use a tool called a fiberoptic nasendoscope, which is a flexible tube with a light and camera at the end, to visualize these areas.
While a procedure called a fine-needle aspiration cytology, guided by ultrasound, is commonly used to examine thyroid nodules in cervical goiters (goiters located in the neck), this technique doesn’t work well for goiters located within the chest due to its complexity and the low risk of hidden thyroid cancer.
The surgical team will use a CT scan to get a detailed look at the goiter and to plan the best surgical treatment method. The CT scan helps to pinpoint the exact size and location of the goiter in reference to important surrounding structures, like the windpipe, food pipe, the main part of the aorta, and large blood vessels. It can also identify any blockage of the windpipe and detect any abnormal lymph nodes.
A multi-disciplinary team including a hormone specialist (endocrinologist), an anesthesiologist, cancer specialist (oncologist), and surgeons who specialize in treating conditions of the head, neck, and chest collaborate to discuss possible cases involving cancer.
How is Substernal Thyroidectomy performed
The primary surgical method for removing a substernal thyroid gland (which is located in the lower front part of your neck) is a procedure known as a “transcervical approach.” This involves making an incision in your neck. However, for about 2% of people, an “extracervical” procedure, which involves making an incision elsewhere in the body, might be a better option.
If you have a growth in both lobes of the thyroid gland, a total removal of the gland should be performed because there’s a high risk (over 10%) that the problem could come back again if the whole gland is not removed. This process is known as a total thyroidectomy. Studies have indicated that for people with non-cancerous thyroid conditions, a total thyroidectomy results in lower chances of disease returning (0% to 0.5%) and has similar risk of complications as compared to just removing part of the gland.
For people with growth only in one lobe and without any indication of cancer, thyroid lobectomy, or the removal of one lobe of the thyroid gland may be done with a low chance of the disease coming back. If you suffer from an overactive thyroid or have thyroid cancer, total thyroidectomy should be the treatment of choice.
To access the thyroid gland during a total thyroidectomy, the surgeon will make a long cut in the lower neck, called an extended Kocher incision. The cut can then be extended up the middle of the breastbone if needed. This approach allows greater exposure to the thyroid gland, making it simpler to remove it. Care is taken during this procedure to preserve important glands and nerves in the area to avoid complications. For very large growths, the muscles near the thyroid may be cut to aid in the procedure.
A very important part of the total thyroidectomy is locating and safeguarding a nerve known as the recurrent laryngeal nerve. Its position can be distorted in the case of large thyroid growths and needs to be carefully identified to avoid damage. A modern technology that aids in this is nerve monitoring, which can track the nerve’s function during the operation.
If an extracervical approach is required, several different techniques can be employed. Historically, full breastbone cut or rib cage surgeries have been performed. However, newer methods like partial breastbone cut, often used in heart surgeries, have shown promising results in thyroid surgeries too. Other methods using special equipment to reduce the size of the thyroid growth followed by neck incision to remove it have also been described.
A special tool called a mediastinoscope, which can be inserted through a neck incision, can be used for benign growths reaching into the chest area up to the level of the main artery of the body. A video-assisted version of this approach can also be employed. There is a small risk (0.4%) of major bleeding with this approach, and sometimes a rib cage surgery may be needed to stop it. In some cases, less invasive techniques are used, like partial endoscopic surgery or even robot-assisted surgery. These have similar risk levels to traditional techniques but can be more expensive.
Possible Complications of Substernal Thyroidectomy
These days, doctors often recommend a procedure called total thyroidectomy over subtotal thyroidectomy. This is primarily because the total thyroidectomy, which consists of removing the whole thyroid, has similar risks but lower chances of the condition coming back. However, a more complex procedure, called substernal thyroidectomy, has slightly higher risk factors. This procedure involves removing an abnormally large thyroid gland – or goiter, which extends into the chest.
For example, people getting substernal thyroidectomy for a goiter located behind the breastbone are more likely to experience problems with their laryngeal nerve, which is responsible for your voice and swallowing, and more likely to develop a long-term calcium shortage.
A study shows that there’s a 33.9% chance of temporary calcium shortage, and a 2.1% chance that it could be permanent, after the removal of this kind of goiter. It also highlights risks of injury to the nerve that controls your voice, with a 2-5.4% chance of a temporary problem on one side, and a 1-2% chance of it being permanent. A less common risk, tracheomalacia, where the windpipe loses its firmness, is a condition occurring in about 3% of these cases.
The same study points out that a substernal thyroidectomy can make finding and preserving the small glands that regulate calcium – the parathyroid glands, a lot more challenging. If these are accidentally removed, it could lead to low levels of calcium in the blood. If you need a second operation, the risk is even higher.
In rare cases, the procedure could lead to fatalities, ranging from 0-15.3%, especially if there is damage to the windpipe and chest wall or the chest bone wound splits open. Infections, a punctured lung, or needing a tube to help you breathe are other rare but possible issues.
Early signs of problems after the surgery might include severe coughing, which could point towards a bleeding complication that is not common but potentially life-threatening. The use of a drainage tube can often help to identify this complication early.
In summary, though a thyroidectomy is a relatively common procedure, it does come with some risks that your healthcare provider will discuss in detail with you. Do note that different types of thyroidectomies have different risks, so make sure you’re informed about the specific procedure recommended for you.
What Else Should I Know About Substernal Thyroidectomy?
Substernal goiters are a type of abnormal growth in the thyroid gland, which is located in your neck. The growth extends into the chest area, which is called the mediastinum. The occurrence rate of such growths ranges widely – as low as 0.2% to as high as 45% in different studies. This means substernal goiters can be quite common.
To manage this effectively, doctors require a proper process for diagnosis and assessment. This helps them understand the severity of the condition and decide the best way to treat it. One important fact to consider is that surgery is widely regarded as the most effective treatment.
The surgery to remove the abnormally grown thyroid tissue can be performed via different methods. Hence, it’s essential that doctors consider individual patient needs and circumstances before crafting a suitable treatment plan for each unique patient.
