Our 16th episode focuses on a topic common in otolaryngology - thyroid nodules. Join us to discuss the evaluation of a patient with thyroid nodules and some pearls for the OR!

Show Notes

 Intro

Hey everyone and welcome to The Oto Approach, a podcast created by medical students for medical students, to teach you about all things otolaryngology. I'm your host Huaqi, and today we're going to talk about thyroid nodules. Tag along for a discussion about this common presentation.

Thyroid nodules are small solitary or cystic masses that arise in the thyroid gland [1]. Thyroid nodules are quite common, and it is estimated that up to 60-70% of the general population has one [2-5]. The incidence of thyroid nodules increases with age, and they are more common in women [2-5]. Thyroid nodules are often identified incidentally when medical imaging is ordered for a different indication, and these incidentally found nodules are sometimes referred to as incidentalomas [2,6,7]. Most thyroid nodules are benign and asymptomatic, with only ~5% being malignant [6,7]. However, the incidence of thyroid cancer has been steadily increasing in Canada [6,7]. The good news is that overall, the five-year survival rate of thyroid cancer in Canada is 98% [6,7].

Anatomy/Physiology

Before diving deeper into thyroid nodules, let's review a bit of basic thyroid anatomy and physiology. For a more detailed review, check out our (upcoming/previous) episode on thyroid physiology!

The thyroid is an endocrine gland located in the anterior neck [8]. It is divided into a left and right lobe connected at the midline by the thyroid isthmus. Up to 50% of the population will have an additional pyramidal lobe of the thyroid which sits superior to the isthmus [9]. The thyroid gland sits superficial to the trachea. Specifically, the thyroid isthmus is commonly found anterior to the 2nd and 3rd tracheal rings [8].

The thyroid gland receives its blood supply from the superior and inferior thyroid arteries and the thyroid ima artery [8]. The superior thyroid artery is the first branch of the external carotid artery, and the inferior thyroid artery branches from the thyrocervical trunk, a branch of the subclavian artery [8]. The thyroid ima artery arises from the aortic arch or the innominate artery and supplies the thyroid isthmus [10]. The innominate artery is also a branch of the aortic arch [8,10].

It is important to recognize that the thyroid gland lies close to the recurrent and superior laryngeal nerves, which innervate the larynx [8]. The recurrent and superior laryngeal nerves are branches of the vagus nerve, which is the 10th cranial nerve [10-12]. The recurrent laryngeal nerve loops under the aortic arch on the left side of the body and then ascends back up the neck in the tracheoesophageal groove; on the right side, it loops under the subclavian artery again traveling up in the tracheoesophageal groove [10-12]. This looping pattern is why the nerve was named recurrent. The recurrent laryngeal nerve provides innervation to all intrinsic muscles of the larynx, except the cricothyroid muscles, and provides sensation to the larynx below the vocal cords [10-12]. The superior laryngeal nerve divides into external and internal branches [12]. The internal branch provides sensation and parasympathetic innervation to the mucous membrane of the larynx above the vocal cords, it is responsible for the cough reflex [12]. The internal branch pierces the thyrohyoid membrane adjacent to the superior thyroid artery [12]. The external branch innervates the cricothyroid muscle [12]. The cricothyroid muscle controls voice pitch [12]. The vagus nerve itself travels all the way into the abdomen, this is the basis of its name, as vagus is Latin for wanderer [13]!

Generally speaking, thyroid hormone controls the metabolic rate of your body. The thyroid gland releases two thyroid hormones: T4 and T3. Approximately 90% of the thyroid hormone released is T4, the inactive form of the hormone, and 10% is the active form, T3. T4 can be converted to T3 in the body’s periphery [14]. The release of T3 and T4 is controlled by the hypothalamic-pituitary-thyroid axis, otherwise known as the HPT axis [15]. The hypothalamus, in the brain, releases thyroid-releasing hormone, otherwise known as TRH, which stimulates the anterior pituitary gland (also in the brain) to release thyroid-stimulating hormone otherwise known as thyrotropin but most commonly called TSH. TSH stimulates the thyroid gland to release T3 and T4 [15]. Each step of the process is regulated through a negative feedback mechanism, where the downstream product will inhibit the further activity of the axis [14]. Investigating this axis can give insight into the causes of hypo or hyperthyroidism, as a dysfunction will impact the thyroid gland and vice versa [15].

The thyroid gland also secretes calcitonin, which is involved in regulating calcium metabolism [8,14]. The parathyroid glands are in close proximity to the thyroid, and are also involved in calcium metabolism [10]. Calcitonin from the thyroid gland decreases the amount of calcium in the body [10]. In contrast, the release of parathyroid hormone from the parathyroid glands increases the amount of calcium in the body [10]. For more details, check out our previous episode on parathyroid physiology!

Differential Diagnosis

As mentioned, most thyroid nodules are benign. However, they must be appropriately investigated to rule out malignancy. The most common cause of a thyroid nodule is a benign follicular adenoma [1]. The most common thyroid malignancy is papillary thyroid carcinoma [16]. However, it is important to have a differential diagnosis for all patient presentations. Using a systematic approach such as the mnemonic VITAMIN C allows you to organize and expand your differential. VITAMIN C stands for Vascular, Infectious, Traumatic, Autoimmune, Metabolic, Iatrogenic, Neoplastic, and Congenital. Since thyroid nodules often present as central neck masses, this may be incorporated into your differential. You may consider vascular causes of neck masses such as carotid body tumors or arteriovenous malformation, although these would be extremely rare. Infectious etiologies such as infectious thyroiditis, reactive cervical lymphadenopathy, or a thyroid abscess would also be considered; these patients often have significant pain due to the ongoing inflammation. Of course, trauma could cause swelling of the neck, or a hematoma, which could be mistaken for a thyroid nodule. However, your history-taking should quickly rule this out. As we mentioned, the thyroid is highly involved in regulating metabolism. For example, a patient with symptoms of hyperthyroidism should be worked up for a functioning thyroid nodule, but we’ll get into this in more detail in a bit. Autoimmune thyroid conditions such as Graves’ disease or Hashimoto’s thyroiditis should be considered [10]. Neoplastic conditions include thyroid or parathyroid cysts, benign nodules, multinodular goiters, metastasis, or malignancy [10]. Thyroglossal duct cysts and branchial cleft cysts would be considered in the differential for congenital neck masses [10].

History

Patients presenting with a thyroid nodule often will have found it incidentally when undergoing medical imaging for an unrelated indication [2,6,7]. Alternatively, they may have noticed a small lump in their neck. For any patient presentation, it is important to take a thorough history. It is important to ask when and how they noticed the nodule? Has it been growing since they noticed it? Have they noticed any other lumps or bumps in their head and neck or anywhere in their body? Any recent skin changes? Large thyroid nodules or multinodular goiters can cause compressive symptoms, such as dysphagia, difficulty swallowing, dysphonia, hoarse voice, or, most concerning, difficulty breathing [16,17]. Since the recurrent laryngeal nerve lives near the thyroid, dysphonia suggests potential compression or malignant invasion of the nerve [16,17]. Dysphagia and dysphonia increase your suspicion of malignancy, and as such, for any patient presenting with dysphagia or dysphonia as a primary complaint, thyroid nodules/cancer should be on your differential [16,17]. Patients may also present with Horner’s syndrome due to the impact on the sympathetic chain located in the neck [16]. Horner's syndrome classically presents with the following triad: unilateral decreased pupil size known as miosis, a drooping eyelid known as ptosis, and decreased sweating known as anhidrosis [16].

Many patients who present with a thyroid nodule will be reasonably concerned about the risk of cancer. It is important to be aware that the classic cancer risk factors do not necessarily apply to thyroid cancer. Thyroid cancer has two clinical risk factors: previous radiation exposure to the head and neck region and a first-degree relative with thyroid cancer [16]. Some patients may not understand what radiation to the head and neck entails, so giving a few examples is helpful, things like working at a dentist's office or undergoing radiation therapy for previous cancer, such as lymphoma. Other things that might raise your suspicion of malignancy are large nodules, rapidly growing nodules, and male sex. While thyroid cancer is more common in women, this is because thyroid nodules in general are much more common in women than in men [17]. However, men presenting with thyroid nodules have a greater likelihood of harboring malignancy [17]. Also, ask about cancer B symptoms for lymphoma - ask if the patient has had any unexpected weight loss, fevers, chills, or night sweats?

Be sure to round out your history by reviewing surgical history, past medical history, social history, medications, and allergies. Finally, review symptoms of hypo and hyperthyroidism. Ask if the patient is experiencing fatigue. Both hypo and hyperthyroidism can cause fatigue, however this is a relatively non-specific symptom [18,19]. Inquire about weight changes and appetite, patients with hypothyroidism may experience weight gain despite low appetite, whereas patients with hyperthyroidism may experience weight loss with an increased appetite [18,19]. Ask about how they respond to changes in temperature, patients with hyperthyroidism may be intolerant to the heat and have excessive sweating. In contrast, patients with hypothyroidism may have cold intolerance and experience coarse or dry skin [18,19]. Have a patient describe their bowel habits, constipation can be associated with hypothyroidism, whereas diarrhea can be associated with hyperthyroidism [18,19]. Ask about musculoskeletal symptoms, patients with hyperthyroidism may complain of tremors or proximal muscle weakness [18,19]. Patients with hypothyroidism may experience weakness, muscle cramps, joint pain and hand and feet numbness [18,19]. For patients who menstruate, ask about their menstrual regularity, as both hypo and hyperthyroidism can cause irregular menstruation [18,19]. Finally, ask about palpitations as they can be associated with hyperthyroidism [19]. If patients have these symptoms, referral to endocrinology should be considered as collaborative care will provide these patients with the best clinical results.

Physical Exam

Your physical exam should begin with the general observation of the patient's neck, be sure to expose below the sternal notch for adequate visualization. On initial inspection, see if you can visualize the thyroid nodule. Can you see any other lumps, bumps, or skin changes in the patient's head and neck area? Next, ask the patient to swallow, or take a drink of water, and observe if you can see the nodule when the thyroid moves up and down during swallowing. Also, be sure to listen to the patient speak and breathe; a high-pitched sound while breathing through a narrow airway known as a stridor could be concerning for airway compression. If you notice dysphonia, this may also be concerning for compressive symptoms or malignant invasion of the recurrent laryngeal nerve. Next, move on to palpation, palpate the thyroid one side at a time, and make sure to give the patient a “heads up” that you are about to palpate the neck as this can be a sensitive area for patients. Ask the patient to turn their head to the left and palpate the left lobe of the thyroid, feeling for any nodules, repeat this on the right side. By asking the patient to turn their head to the side you are palpating, it relaxes the musculature and tissue on that side of the neck, facilitating palpation of the thyroid. Don’t forget to palpate the isthmus in the midline! Finally, ask the patient to swallow while palpating their thyroid gland to again feel for any nodules or irregularities [20].

Continue your exam with a thorough assessment of the head and neck. Palpate the cervical lymph nodes, assessing for significant lymphadenopathy or other palpable masses. As mentioned, look for lumps, bumps, or skin changes. Inspect the oral cavity and oropharynx, inspect the external ear, perform otoscopy, and perform anterior rhinoscopy. Finally, with the help or supervision of a staff or resident, perform nasopharyngoscopy and laryngoscopy, and look for any abnormalities. More details on what you are looking for when performing nasopharyngoscopy can be found in our chronic rhinosinusitis episode. Be sure to assess the vocal cords. As mentioned, the laryngeal nerves near the thyroid control the vocal cords, and therefore we must ensure that there is no vocal cord paralysis. Have the patient say “Eeeeeeeeeee” or “huh huh huh” to assess the movement of the vocal cords with the nasopharyngoscope.

Finally, round out your physical by looking for signs of hyper or hypothyroidism. Always start by assessing a patient's vitals! Tachycardia, otherwise known as a fast heartbeat greater than 100 beats per minute, can be seen in hyperthyroidism [18,19]. In contrast, hypothyroidism can cause bradycardia, otherwise known as a slow heartbeat of less than 60 beats per minute [18,19]. Throughout the encounter, you should be assessing the patient's affect. An anxious affect can be associated with hyperthyroidism [18,19]. More of a depressed affect is associated with hypothyroidism [18,19]. Next, ask them to hold their arms out straight, do you see a tremor in their hands? This could be a sign of hyperthyroidism [19]. Also, look at their movements; slow movements, known as bradykinesia, can signify hypothyroidism [18]. Move on to feeling their skin and hair; moist, warm skin or thin hair is common in hyperthyroidism, whereas hypothyroid patients will often have dry, coarse skin or coarse hair [18,19]. Have a look at the patient's eyes; loss of the lateral ⅓ of a patient's eyebrows can be seen in hypothyroidism which is commonly called “Queen Anne’s sign,” whereas a widened palpebral fissure, the lateral space between the corners of the eyelids, can be seen in hyperthyroidism [18,19]. Other eye findings such as bulging eyeballs known as exophthalmos, a drooping eyelid known as ptosis, inflammation of the eye known as conjunctivitis, or pain with eye movement can be seen with an autoimmune condition called Graves’ disease. Graves’ disease causes hyperthyroidism [18,19]. Have the patient follow your finger with their eyes and move your finger quickly from a high position to a low position. If the upper eyelid does not appropriately follow the eye’s downward gaze, the patient may be experiencing a lid lag, a sign of hypothyroidism. Assess the patient's reflexes; hyperreflexia can be a sign of hyperthyroidism, whereas slow relaxation of an ankle jerk reflex can signify hypothyroidism [18,19]. Listen to the patient’s bowel sounds; overactive vs. underactive bowel sounds may be related to hyper vs. hypothyroidism [18,19]. Finally, have a look at the patient's nails, whitening of the nailbed or onycholysis may also be a sign of hyperthyroidism [19]. Again, hypo and hyperthyroidism often warrant referral to endocrinology!

Work-up and Management

Multiple investigations can be performed for a thyroid nodule. Typically investigation will begin with laboratory measurement of TSH and ultrasound of the thyroid [17]. If the TSH is suppressed or low, it is likely a hyperfunctioning or “hot” nodule as the secretion of thyroid hormone would suppress the release of TSH- in other words, there is no need to stimulate the thyroid further as the node is already acting autonomously to produce thyroid hormone. These hyperfunctioning nodules are unlikely to be malignant, most commonly, they are hyperfunctioning follicular adenomas [17]. However, a radionuclide scan should be performed to assess for a toxic multinodular goiter [17]. Hyperfunctioning nodules and toxic multinodular goiters are typically treated with radioiodine ablation [17]. The hyperactive nodules tend to suppress the hormonal action of the rest of the thyroid gland tissue therefore when the patient ingests the radioactive iodine, these hyperfunctioning nodules selectively take up the radioactive iodine, and this selectively ablates the hyperactive nodules [21]. However, patients may still require synthetic thyroid hormone replacement known as Synthroid or Levothyroxine [21]. 

Long-term pharmacotherapy with anti-thyroid medications is also a treatment option for hyperthyroidism [18]. Methimazole or propylthiouracil, otherwise known as PTU, are both medications which inhibit thyroid hormone synthesis [18]. Hyperthyroidism is often managed by an endocrinologist, and collaboration plays an important role in ensuring the best patient care. 

On the other hand, non-functioning nodules, in other words, ones which are not producing hormones, are more concerning for malignancy. Many centers will use the Thyroid Imaging Reporting and Data Systems or TI-RADS, to report thyroid ultrasound results [22]. This will give the thyroid nodule a score based on ultrasound features and recommend which nodules warrant a fine needle aspiration or FNA biopsy [22,23]. The higher the TIRADS score, the higher the risk of malignancy [22,23]. The TIRADS scoring system is based on five categories of ultrasound findings [22,23]. The five categories are composition, echogenicity, shape, margins, and echogenic foci [22,23]. Each of the five categories is scored individually, these scores are added together to give an overall TIRADS score [22,23]. Solid nodules, those with hypoechoic features, irregular margins, or calcifications receive higher scores [22,23]. A higher TIRADS score indicates a more suspicious thyroid nodule [22,23]. Based on the TIRADS score there will be a recommended next step based on the degree of suspicion, next steps range from a suggestion of no FNA biopsy to follow up to FNA biopsy [22,23]. However, clinical judgment and shared decision-making often take precedent in planning.

FNA biopsies can be performed with or without ultrasound guidance. However, ultrasound guidance can provide increased accuracy in trained users. Many otolaryngologists are trained in thyroid ultrasound and ultrasound-guided FNA, however, these can also be referred to radiologists to perform. FNA biopsy is the standard of care over core biopsies to reduce the risk of malignant seeding, where a biopsy could dislodge and spread cancer cells [10]. However, this is a rare occurrence with both core or FNA biopsies [24].

The results of FNA biopsies are classically reported by The Bethesda System for Reporting Thyroid Cytopathology [25]. This categorizes the FNA biopsy results into six categories. A Bethesda category 1 is a non-diagnostic or unsatisfactory sample [25]. A Bethesda category 2 is defined as benign; this suggests a 0-3% risk of malignancy  [25]. A Bethesda category 3 is defined as atypia of undetermined significance or follicular lesion of undetermined significance, otherwise known as AUS or FLUS [25]. This is an indeterminate category in a bit of a gray area. The rate of malignancy for AUS or FLUS nodules is stated to be 6-30%, but varying malignancy rates are reported in the literature depending on the center, and population assessed [25]. The fourth Bethesda category is follicular neoplasm, or suspicious for a follicular neoplasm. This is reported to have a 10-40% risk of malignancy [25]. The fifth Bethesda category is suspicious for malignancy, suggesting a 45-75% risk of malignancy [25]. Finally, the sixth Bethesda category is malignant, which carries a 94-99% risk of malignancy [25].

Generally speaking, the next steps in treatment based on FNA results are observation, repeat FNA, hemithyroidectomy, or total thyroidectomy [10]. A hemithyroidectomy is when only one lobe of the thyroid gland is removed in surgery. This allows removal of the nodule and definitive diagnosis of pathology with the surgical specimen. In contrast, a total thyroidectomy removes all thyroid tissue in both lobes and the isthmus. Patients with benign nodules may be more likely to undergo observation. In contrast, patients with indeterminate nodules may undergo repeat FNA or hemithyroidectomy with the potential for further treatment based on surgical pathology results [10,25]. Indeterminate thyroid nodules may benefit from molecular testing to further stratify their risk of malignancy. However, this is currently not publicly funded in Canada. Patients with a higher risk of malignancy may be more likely to undergo total thyroidectomy. Clinical or imaging signs of extrathyroidal extension and cancer staging using the TNM system can help guide indications for further surgical treatment, including the necessity of neck dissections [10]. Shared decision-making with patients and variations in clinical practice will dictate the exact next steps [26]. Chemotherapy and radiation therapy have limited roles in treating thyroid cancer; however, radioactive iodine ablation can be used post-thyroidectomy to ensure any residual thyroid tissue is ablated [16]. 

The AMES tool is often used to stratify higher risk well-differentiated thyroid cancer. Well-differentiated thyroid cancer includes papillary and follicular thyroid carcinoma. The AMES tool describes risk based on Age, Metastasis, Extent of disease, and size [10]. Female patients >41 or <14 years old and male patients >51 or <14 years old have a lower 10 year survival rate [10]. Similarly, patients with distant metastasis or extrathyroidal extension have a decreased prognosis for 10 year survival [10]. Finally, thyroid cancer >5 cm is also a poor prognostic factor [10].

 Clinical surveillance of thyroid nodules can vary depending on practice preference, but typically this refers to serial ultrasounds and physical examinations performed at increasingly spread-out intervals to see if the thyroid nodule is growing or gaining more concerning features, and if it is, an FNA should be performed [27]. Patients should be counseled to seek medical attention if they notice the nodule growing or if they experience dysphagia, dysphonia, difficulty breathing, stridorous breathing, or any B symptoms.

Risks of Thyroidectomy

When counseling patients on thyroidectomy, it is important to inform them of all the benefits and risks with the surgery. Common to all surgeries, patients undergoing thyroidectomy have the risks of bleeding, infection, and complications associated with general anesthesia. Thyroidectomy specifically has risks of damage to the recurrent laryngeal nerve. As mentioned, the recurrent laryngeal nerve innervates all intrinsic muscles of the larynx except for the cricothyroid muscle, therefore damage to this nerve can result in dysphonia and/or dysphagia [10]. Unilateral damage to the recurrent laryngeal nerve can result in dysphonia and/or dysphagia and can increase the risk of aspiration pneumonia as airway protection during swallowing is compromised [10,16]. More concerning is bilateral damage to the recurrent laryngeal nerve, resulting in postoperative airway compromise due to bilateral vocal cord paralysis [10]. The external branch of the superior laryngeal nerve is also at risk of injury, and remember, this is the nerve that innervates the cricothyroid muscles which controls voice pitch [12,28]. Therefore, damage to this nerve will result in patients having poor voice pitch control [12,28]. The internal branch of the superior laryngeal nerve is less commonly injured during thyroidectomy. However, damage would result in loss of the laryngeal cough reflex, which is triggered when solids or liquids enter the laryngopharynx, therefore, this could also increase the risk of aspiration pneumonia [12,16]. These symptoms may be temporary due to traction on the nerve intraoperatively and may resolve over time, or they may be permanent due to intraoperative damage to the nerve [16,27]. 

There is also a risk of damage to the parathyroid glands, which reside near the thyroid. Damage to the parathyroid glands can result in hypocalcemia due to hypoparathyroidism, most patients will have calcium supplemented post-thyroidectomy. Often hypocalcemia is temporary. Chvostek and Trousseau's signs are the classic signs of severe hypocalcemia/hypoparathyroidism [29]. Chvostek sign is twitching of facial muscles when tapping on the patient's cheek just anterior to the ear, where the seventh cranial nerve, the facial nerve, resides [29]. Trousseau's sign is an involuntary contraction of wrist and hand muscles when a blood pressure cuff compresses the patient’s arm [29]. These signs occur because the low calcium decreases the neuronal potential required at the motor endplate [29]. If parathyroid tissue is damaged intraoperatively, it could be re-implanted into the sternocleidomastoid muscle and regain secretory functions [30]. Listen to our previous episode on parathyroid physiology for more details! 

Total thyroidectomy will result in hypothyroidism- and this should be intuitive to you now! Therefore, hormone replacement, in the form of Synthroid or levothyroxine, will be required long-term. 

Finally, there is a risk of post-op neck hematoma, causing compression on vascular structures resulting in significant edema and obstruction of the airway [10]. A neck hematoma requires urgent evacuation [10].

Patients who underwent a hemithyroidectomy and had malignant pathology results may be recommended to have a completion total thyroidectomy performed [17]. This should be counseled pre-operatively.

Pathology Results and Follow Up

The most common cause of a thyroid nodule is a benign follicular adenoma, but it is important to be aware of the different thyroid cancer pathologies.

Papillary thyroid cancer is the most common and luckily, generally is the least concerning thyroid cancer, and it often has the best prognosis. However, there are different variants of papillary thyroid cancer. This is important to keep in mind, as some rarer variants, such as the tall cell variant, unfortunately, have a much poorer prognosis. Follicular thyroid cancer is more aggressive than papillary but still carries a good prognosis [10,16]. Medullary thyroid cancer is commonly found in patients with multiple endocrine neoplasms or MEN disease, where, as the name implies, these patients develop multiple different endocrine neoplasms [10,16]. Specifically, MEN 2a and 2b are associated with medullary thyroid cancer [10,31,32]. MEN 2a, also known as Sipple syndrome is characterized by medullary thyroid cancer, pheochromocytoma (a type of adrenal gland tumor), and parathyroid hyperplasia [10,31,32]. MEN 2b is characterized by medullary thyroid cancer, pheochromocytoma, and a specific phenotype typically described with thick lips and tongue, with a thin, slender build [10,31,32]. MEN 1, also known as Wermer syndrome, is not associated with thyroid cancer but rather is characterized by pituitary adenomas, parathyroid hyperplasia, and pancreatic islet cell tumors [10,31,32]. Anaplastic thyroid cancer is the most aggressive thyroid cancer. It has high recurrence rates, commonly presents with rapid and extensive lymphatic spread, and survival can be in the order of six months [10,33]. Often, surgical treatment is no longer viable, and palliative care is most appropriate [10,13]. Palliative chemotherapy or radiation therapy may be offered to patients with anaplastic thyroid cancer [16]. Finally, patients may also have primary lymphoma of the thyroid, with non-Hodgkin's B Cell lymphoma being the most common [10].

If a patient has had a total thyroidectomy, thyroid cancer recurrence can be followed by measuring thyroxine levels. This is true for all except medullary thyroid cancer which should be followed by measuring calcitonin.

Broad strokes thyroidectomy

Now… you are on your otolaryngology rotation and joining the team for a thyroidectomy in the OR tomorrow, what are some key things you should know?

Thyroidectomy starts with opening the skin, it is important to know the layers of the neck when approaching the thyroid: you will go through the skin, subcutaneous tissue, fat, platysma, investing layer, and the pre-tracheal layer of the deep cervical fascia [16].

You may be asked what the strap muscles are? These are pairs of four muscles: the thyrohyoid, omohyoid, sternohyoid, and sternothyroid, which can be remembered with the acronym, TOSS. They move the hyoid bone during swallowing, and their origins and insertions are intuitively named. The strap muscles, specifically the sternothyroid and sternohyoid, are divided along the midline raphe (an avascular plane dividing the muscles at the midline over the thyroid gland) to access the thyroid gland during surgery [16].

The recurrent and external branches of the superior laryngeal nerves are at risk of injury during thyroidectomy. What are some ways to identify the recurrent laryngeal nerve? The five landmarks would be the tracheoesophageal groove, the tubercle of Zuckerkandl, a postero-lateral extension of the thyroid lobe, Berry’s ligament, a suspensory ligament attaching the thyroid to the trachea, and the inferior thyroid artery [16,34]. The external branch of the superior laryngeal nerve resides within “Joll’s Triangle”, which is defined superiorly by the superior attachment of the strap muscles, medially by the neck midline, and laterally by the upper pole of the thyroid lobe and the superior thyroid vessels [34].

The superior parathyroid glands classically are deep to the recurrent laryngeal nerves, whereas the inferior parathyroid glands are typically superficial [35].

Finally, to avoid a post-op hematoma, you will notice that when closing the strap muscles of the neck, they are not tightly approximated inferiorly. Instead, a small space is left to allow blood to flow out. The main reason for approximating the strap muscles is to avoid a “button-hole” effect, which is when the overlying skin can stick to the trachea in the post-operative period, leaving a dimple in the skin.

This script was written by Kalpesh Hathi, it was revised by Dr. Travis Pickett, Dr. Christopher Chin, Aileen Feschuk, Emily Cheng, and Katie Oxford.

We would like to extend our sincerest thanks to the Saint John Regional Hospital Department of Surgery within the Horizon Health Network for their generous support.

Thank you so much for listening to our podcast! We hope you’ll tune in to our next episode! Please head to our website at www.theotoapproach.com for our show notes, and to sign up for our newsletter to stay up to date with our latest episodes.

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