Thyroidectomy

Learning objectives

Thyroidectomy is the surgical removal of all or part of the thyroid gland
The surgery is performed to treat thyroid disorders including thyroid cancer, a noncancerous enlargement of the thyroid (goiter), and overactive thyroid (hyperthyroidism)
A skin crease incision is made approximately 4 cm above the sternum
The recurrent laryngeal nerves and parathyroid glands should be preserved

Total thyroidectomy: The entire thyroid gland is removed
Near-total thyroidectomy: Both lobes of the thyroid are removed except for a small amount of thyroid tissue (on one or both sides) in the vicinity of the recurrent laryngeal nerve entry point and the superior parathyroid gland
Partial thyroidectomies
- Hemithyroidectomy or unilateral thyroid lobectomy: One lobe of the thyroid is removed
- Isthmusectomy: The band of tissue (thyroid isthmus) connecting the two lobes of the thyroid is removed
- Open thyroid biopsy: The thyroid nodule is removed directly (rarely performed)

Thyrotoxicosis

2% of females, 0.02% of males
Graves disease (hyperthyroidism) in younger women is the most common cause (up to 80%)
Multinodular goiter (older patients)
Toxic solitary nodule
Other causes: Thyroiditis, pregnancy, drug-induced (amiodarone)

Thyroid malignancy

Papillary (80%)
- 30-40 years old
- 95% 10-year survival rate
Follicular (10%)
- May be hormone producing
- Older population
- 85% 10-year survival rate
Medullary (8%)
- Older patients
- May be associated with multiple endocrine neoplasias
- May produce calcitonin
- 65% 10-year survival rate
Anaplastic (1%)
- Mean survival 6 months from diagnosis

Hypothyroidism → need for lifelong thyroid hormone replacement
Recurrent laryngeal nerve palsy
- Unilateral damage: Temporary or permanent hoarseness
- Bilateral damage: Airway obstruction and acute respiratory distress
  → emergency tracheostomy may be required
Damage to the parathyroid glands → temporary or permanent hypoparathyroidism and hypocalcemia
Anesthetic complications
Infection
Hemorrhage/hematoma which may compress the airway → acute respiratory distress
Stich granuloma
Chyle leak

Preoperative assessment

Detailed history and examination

Airway
- Marked tracheal deviation
- Stridor or respiratory distress, especially when supine
- Assess vocal cords movement to recognize preexisting laryngeal nerve palsy
Cardiovascular system
- Hyperthyroidism can cause tachycardia, atrial fibrillation, or heart failure
- Large goiters may obstruct venous drainage, and superior vena cava obstruction can occur with retrosternal spread
Eyes
- Protect the eyes from intraoperative drying or trauma in case of lid retraction and exophthalmos
Other conditions
- May be part of multiple endocrine neoplasia syndromes, and conditions such as diabetes mellitus, hyperparathyroidism, and pheochromocytoma must be considered

Drug treatment in hyperthyroidism

Patients should be clinically and biochemically euthyroid before surgery

Carbimazole: Inhibits iodination of tyrosyl residues in thyroglobulin
Propylthiouracil: Same as carbimazole but also reduces peripheral deiodination of T4 to T3
β-blockers: Control cardiovascular effects; propranolol also decreases the extrathyroidal conversion of T4 to T3
Iodine: Give potassium iodine for 7-10 days preoperatively