ERGU: Thyroid Surgery

A thyroid nodule of ________ can be observed.

< 1 cm

What is helpful in preservation of the recurrent laryngeal nerve during a thyroidectomy?

A bipolar cautery is helpful in preservation of the recurrent laryngeal nerve during a thyroidectomy.

What is a nerve monitor?

A nerve monitor is used to determine the location of the recurrent laryngeal nerve by measuring action potentials. It stimulates the nerve to prevent touching the recurrent laryngeal nerve while dissecting.

What is a robotic thyroidectomy?

A robotic thyroidectomy is removal of the thyroid through the axilla. This is good in specific patients.

What is the most common imaging modality for thyroid disease?

A sonogram is the most common imaging modality for thyroid disease.

Epidemiology of Ectopic Thyroid Sex:

Epidemiology of Ectopic Thyroid Sex: F > M 1:7

How is external branch of the superior laryngeal nerve injury treated?

External branch of the superior laryngeal nerve injury is treated with speech therapy.

How is hypocalcemia post-thyroidectomy prevented?

Hypocalcemia post-thyroidectomy can be prevented with meticulous dissection. There is no reason to take out the parathyroid glands with the thyroid gland, and care must be taken to not devascularize the parathyroid glands.

A patient presents with hypocalcemia post thyroidectomy. What is the cause?

Hypocalcemia post-thyroidectomy is caused by inadvertent damage or removal of the parathyroid glands or supply to the parathyroid gland.

How is injury to the external branch of the superior laryngeal nerve prevented?

Injury to the external branch of the superior laryngeal nerve is prevented with meticulous dissection.

Endoscopy Thyroidectomy

Most endoscopic techniques have not been popular in the US. It is popular in Asian countries.

What is the most common thyroid cancer?

Papillary thyroid cancer is the most common thyroid cancer.

What is the one cancer in which metastatic cancer can be cured with surgery?

Papillary thyroid cancer is the one cancer in which metastatic cancer can be cured with surgery.

Why is an ultrasound performed when investigating thyroid disease? (6)

US: 1. confirms palpable thyroid nodule. 2. looks for additional nodules. 3. looks for suspicious characteristics of nodules. 4. US-directed FNA. 5. evaluates neck and FNA. 6. is used for follow up of nodules.

How can you differentiate between a thyroid cyst and a thyroglossal duct cyst?

You can differentiate between a thyroid cyst and a thyroglossal duct cyst by asking the patient to protrude the tongue. A thyroglossal duct cyst moves with protrusion of the tongue while a thyroid cyst does not move with protrusion of the tongue.

Most thyroid nodules are _______.

benign

The inferior thyroid veins drain into the _______

brachiocephalic vein.

Radioactive I-131 is indicated in ______.

high risk thyroid cancers

The middle thyroid veins drain into the ______.

internal jugular vein

The superior thyroid veins drain into the ______.

internal jugular vein

In patients with thyroid cancer < 1 cm with no lymph node involvement, a _______ is performed.

lobectomy

The thyroid is bound by _________ fascia along with (3).

pretracheal; the trachea, esophagus, and pharynx

Radioactive I-131 is not recommended for _______.

unifocal papillary microca

Thyroid nodules are more common in (sex).

women

How is unilateral vocal cord paralysis treated? (3)

1. Autocorrection: Corrective procedures may be delayed for at least 6 months to allow time for improvement in a reversible injury. 2. Medialization: Medialization is the most commonly used surgical correction. 3. Reinnervation

What are the two types of follicular cell thyroid cancer?

1. Differentiated 2. Anaplastic

How is bilateral vocal cord paralysis treated? (3)

1. Emergency Tracheotomy: Emergency tracheotomy may be required. 2. Endotracheal Intubation: Endotracheal intubation should be performed prior to tracheotomy. 3. Cordotomy and Arytenoidectomy: These are the most commonly performed surgical procedures to enlarge the airway and may permit decannulation of a tracheostomy.

What are the two major sources of thyroid cancer?

1. Follicular Cells 2. Parafollicular Cells (C Cells)

Routine Investigation for Thyroid Disease (7)

1. History 2. Physical Exam 3. Laryngoscopy: Are the vocal cords moving? Laryngoscopy can also rule out malignancy by ruling out vocal cord compression or paresis. 4. Thyroid Function Tests: TFTs determines thyroid function. 5. CBC 6. Calcium 7. Thyroid Antibodies: This will rule out autoimmune causes.

What are four categories of minimally invasive thyroidectomies?

1. Mini Incision 2. Endoscope Assisted 3. True Endoscopic 4. Robotic

Symptoms of Goiter (4)

1. Neck Swelling 2. Hoarseness: This is due to compression of the recurrent laryngeal nerve. Tracheal compression can also aid hoarseness. 3. Dysphagia: Dysphagia is due to compression of the esophagus. 4. Stridor: Stridor is due to recurrent laryngeal nerve involvement as well as compression of the trachea.

How is an ectopic thyroid treated? (4)

1. Observation: If the thyroid is small, it can be observed. 2. Medical Therapy: Thyroxine supplements can be used to suppress TSH. 3. Surgery: If symptomatic, the thyroid can be removed. 4. I-131

What are the three types of differentiated thyroid cancer?

1. Papillary Thyroid Cancer 2. Follicular Thyroid Cancer 3. Hurthle Cell Thyroid Cancer

What are the two types of medullary thyroid cancer?

1. Sporadic 2. Familial/Syndromic

Special Investigations for Thyroid Disease (5)

1. Thyroid Scan 2. Sonogram: A sonogram is the most common imaging modality for thyroid disease. 3. CT Scan 4. MRI 5. FNA: This aids in the histology of the thyroid disease.

Differential diagnosis of thyroid nodules include: (5).

1. adenomas. 2. colloid/hyperplastic nodules. 3. cysts. 4. thyroiditis. 5. malignancy.

Risk factors for thyroid cancer include: (5)

1. age. 2. sex. 3. history of low dose radiation to the neck. 4. rapid growth. 5. a sudden change in size of a nodule.

The lymph nodes dissected in thyroid cancer include: (2)

1. central neck dissection (CND) for cN1. 2. lateral neck dissection for clinically positive disease.

Indications for total thyroidectomy include: (5)

1. grossly palpable disease in both lobes. 2. a high risk patient with a high-risk tumor (i.e. high-risk pathology). 3. radiated patient. 4. a young patient with large nodal metastasis to facilitate radioactive iodine therapy. 5. a patient with distant metastasis likely to require radioactive iodine therapy.

Complications of thyroid surgery include: (6)

1. hemorrhage. 2. nerve damage. Nerve damage may occur to the recurrent laryngeal nerve or the superior laryngeal nerve, as the paratracheal lymph nodes are closely related to these nerves, leading to voice and airway complications. 3. hypoparathyroidism. 4. infection. 5. scar. 6. damage to the trachea and esophagus.

In patients with thyroid cancer between one to four cm and no lymph node involvement, a (2) are indicated.

1. lobectomy OR 2. thyroidectomy "Thyroid lobectomy alone may be sufficient initial treatment for low risk papillary and follicular carcinomas; however, the treatment team may choose total thyroidectomy to enable RAI therapy or to enhance follow-up based upon disease features and/or patient preferences."

Thyroid nodules indicated for surgery include: (9)

1. malignant or suspicious cytology. 2. a rock hard mass. 3. vocal cord paralysis. 4. neck node involvement. 5. compressive symptoms. 6. cosmetic reasons. 7. a patient's concern with malignancy. 8. a recurrent cyst or cyst > 4 cm. 9. increasing size on follow-up exams.

Methods of lymph node dissection include:

1. modified neck dissection. 2. preserving the SCM, with preservation of the IJV, accessory nerve, and submandibular gland (Level I). 3. radical neck dissection. A radical neck dissection is rarely indicated. * Berry picking is not recommended, as there is a high incidence of neck recurrence.

A lingual thyroid is mostly seen in females, particularly during (3).

1. puberty. 2. pregnancy. 3. menopause. * This is because plasma TSH increases, leading to hypertrophy of the ectopic tissue.

Thyroglossal duct cysts are lined with (3).

1. respiratory epithelium. 2. squamous epithelium. 3. both.

The thyroid gland is deep to the (2).

1. sternothyroid muscle. 2. sternohyoid muscle.

The blood supply of the thyroid is (3).

1. superior thyroid artery. The superior thyroid artery supplies the superior and anterior portions and is a branch of the external carotid artery. 2. inferior thyroid artery. The inferior thyroid artery supplies the inferior and posterior portions and is a branch of the thyrocervical trunk. 3. thyroid ima artery. The thyroid ima artery is a branch from the brachiocephalic trunk.

The thyroid gland is drained by (3).

1. superior thyroid veins. The superior thyroid veins drain into the internal jugular vein. 2. middle thyroid veins. The middle thyroid veins drain into internal jugular vein. 3. inferior thyroid veins. The inferior thyroid veins drain into the brachiocephalic vein.

The thyroid gland wraps around (2).

1. the cricoid cartilage. 2. the superior tracheal rings.

The recurrent laryngeal nerve can be clipped during a thyroidectomy at/near: (3).

1. the tracheoesophageal groove during paratracheal nodal dissection. 2. the crossing of the inferior thyroid artery. 3. the ligament of Berry, which contains small vessels.

A total or near-total thyroidectomy is indicated if (4):

1. thyroid cancer is > 4 cm. 2. there is gross extrathyroidal extension. The capsule of the thyroid spread into the surrounding muscles or into the trachea. 3. there are clinically apparent LN mets (cN1). 4. there are clinically apparent distant mets (cM1).

What is a thyroglossal duct cyst?

A thyroglossal duct cyst is a congenital anomaly that presents as a superficial cyst in the midline of the neck anterior to the trachea and superior to the thyroid from the foramen cecum to the thyroid due to the failure of the thyroglossal duct to involute. In about 70% of cases, microscopic foci of ectopic thyroid gland tissue can be found, usually within the cyst wall.

How is a thyroglossal duct cyst treated?

A thyroglossal duct cyst is treated with surgical excision of the cyst with the middle third of the hyoid bone in a procedure called Sistrunk's procedure.

What is an ectopic thyroid?

An ectopic thyroid is an abnormal location of the thyroid gland due to the failure to descend normally during development. The thyroid can be arrested at any location on its path of descent, from foramen cecum to any part of the neck.

Papillary thyroid carcinoma is associated with ______ mutations.

BRAF

What is the most common molecular marker of thyroid cancer?

BRAF is the most common molecular marker of thyroid cancer.

How does bilateral vocal cord paralysis present? (3) When does it present?

Bilateral vocal cord paralysis presents immediately after extubation with biphasic stridor, respiratory distress, or both.

Follicular thyroid carcinoma is associated with ______ mutations.

RAS

What is recurrent laryngeal nerve injury?

Recurrent laryngeal nerve injury results in true vocal fold paresis or paralysis. It occurs in 1 to 2% of thyroid surgeries.

How is hypocalcemia post-thyroidectomy treated?

Severe hypocalcemia post-thyroidectomy is treated with IV calcium gluconate.

Surgery Type: Endoscopic Surgery Invasiveness: Expense:

Surgery Type: Endoscopic Surgery Invasiveness: minimally invasive Expense: maximally expensive

The location of the inferior parathyroid gland is more variable than the superior parathyroid gland. Why?

The location of the inferior parathyroid gland is more variable than the superior parathyroid gland. This is because the inferior parathyroid glands are derived from the third pharyngeal pouch while the fourth parathyroid gland is derived from the fourth pharyngeal pouch.

What is the lymphatic drainage of the thyroid?

The lymphatic drainage of the thyroid is the pretracheal, prelaryngeal, and paratracheal lymph nodes (Level VI/central compartment lymph nodes) to the deep cervical lymph nodes (Levels I, III, IV, and V).

What is the most common ectopic thyroid site?

The most common ectopic thyroid site is the lingual thyroid.

What is the pyramidal lobe of the thyroid?

The pyramidal lobe of the thyroid is an anatomical variant that represents a persistent remnant of the thyroglossal duct. It is present in 10-30% of the population.

What is the second most common thyroid cancer?

The second most common thyroid cancer is follicular carcinoma.

How does the thyroid develop?

The thyroid develops from the median endodermal thickening on day 24 of development. The median endodermal thickening develops into the thyroid diverticulum by the 5th week of life. Around Week 7, the thyroid diverticulum forms two lobes, and the thyroid gland descends to its normal anatomical position in the anterior neck via the thyroglossal duct. The thyroglossal duct involutes by the 10th week of gestation. Around the end of three months, the thyroid gland begins to function.

What is the thyroid gland?

The thyroid gland is an endocrine gland encapsulated in a thin fibrous capsule located at the anterior neck at the level of the C5-T1 vertebrae. The thyroid is about 4 to 5 cm in length, 2 to 3 cm in greatest transverse dimension, and 1.5 to 2 cm in greatest anterior-posterior dimension. The isthmus is about 1 cm in greatest transverse and vertical dimensions.

What is the treatment for metastatic thyroid cancer?

The treatment for metastatic thyroid cancer is thyroidectomy with resection of the metastasis (neck and mediastinal neck dissection or isolated lung or bone metastasis).

How does unilateral vocal cord paralysis present? (4) When does it present?

Unilateral vocal cord paralysis presents with hoarseness or breathiness that may not manifest for days to weeks post-op. Other potential sequelae are dysphagia and aspiration.

What is the clinical relevance of the pyramidal lobe?

When performing a thyroidectomy, all tissue must be removed for effective outcomes.

How does injury to the external branch of the superior laryngeal nerve present?

When the external branch of the superior laryngeal nerve is injured, the patient has a weak voice for high pitched tones as well as an altered singing voice.

Thyroid follicular cells are derived from ______.

endoderm

The superior thyroid artery is a branch of the _______.

external carotid artery (ECA)

The superior parathyroid gland originates from the ________.

fourth pharyngeal pouch

The external branch of the superior laryngeal nerve is also known as the _______.

nerve of Galli-Curci Amelita Galli-Curci was a singer whose external branch of the superior laryngeal nerve was affected.

The inferior thyroid artery supplies: (2)

the inferior and posterior portions of the thyroid

The superior thyroid artery supplies: (2)

the superior and anterior portions of the thyroid

The inferior parathyroid gland originates from the ________.

third pharyngeal pouch

The inferior thyroid artery is a branch of the ________.

thyrocervical trunk