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Thyroidectomy - Surgical Steps with Illustrations

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Indications

• Thyroid cancer
• Symptomatic goitre (compressive symptoms: dysphagia, dyspnea, hoarseness)
• Hyperthyroidism unresponsive to medical management (Graves disease, toxic multinodular goitre)
• Suspicious or indeterminate thyroid nodules

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Types of Resection

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Preoperative Preparation

1. Biochemical assessment - thyroid function tests, serum calcium (to screen for concurrent hyperparathyroidism)
2. Neck ultrasound + FNA biopsy of suspicious nodules
3. For hyperthyroidism - render patient euthyroid with propylthiouracil or methimazole; Lugol's iodine within 10 days of surgery reduces gland vascularity
4. Voice assessment - preoperative laryngoscopy or transcutaneous laryngeal ultrasound to document baseline vocal cord function
5. Airway assessment - CT neck for deviation/tracheal compression, especially with large goitres

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Surgical Steps

Step 1 - Anesthesia and Positioning

• General endotracheal anesthesia; if intraoperative nerve monitoring (IONM) is planned, a specialized neuromonitoring ETT with vocal cord contact electrodes is used
• Patient supine, both arms tucked at sides
• Back raised 20 degrees (shoulder roll), neck extended to expose the anterior neck
• A "beach chair" position with a roll under the shoulders provides optimal exposure

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Step 2 - Skin Incision (Kocher's Incision)

• A collar (transverse) incision is made approximately 2 cm above the sternal notch, placed in a natural skin crease for cosmesis
• Length typically 4-6 cm; extended for large goitres
• Incision deepened through skin, subcutaneous fat, and the platysma muscle

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Step 3 - Raising Subplatysmal Flaps

• Superior flap raised to the level of the thyroid notch
• Inferior flap raised to the sternal notch
• Dissection proceeds in the avascular plane deep to the platysma

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Step 4 - Division of Strap Muscles and Exposure of the Thyroid

• The midline raphe between the sternohyoid muscles is divided vertically along the linea alba
• Strap muscles (sternohyoid and sternothyroid) are retracted laterally to expose the thyroid gland
• The isthmus can be divided at this stage to allow separate lobe mobilization and to work through a smaller incision
• The inferior thyroid vein is identified and ligated

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Step 5 - Mobilization of the Superior Pole

• The superior pole of the thyroid is retracted inferiorly and medially
• The avascular space between the cricothyroid muscle and the superior pole is developed by blunt dissection
• The superior thyroid artery and vein are individually ligated and divided close to the thyroid capsule - this protects the external branch of the superior laryngeal nerve (EBSLN)
• The EBSLN runs within 1 cm of the superior thyroid vessels in most patients and injury causes loss of the upper pitch register ("opera singer's nerve")

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Step 6 - Ligation of the Middle Thyroid Vein

• The middle thyroid vein drains the middle third of each lobe
• It is ligated and divided to allow medial rotation of the thyroid lobe for posterior dissection

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Step 7 - Identification and Preservation of the Recurrent Laryngeal Nerve (RLN)

• The RLN is the most critical structure to identify and protect during thyroidectomy
• On the right side - the RLN loops around the subclavian artery and approaches the tracheoesophageal groove obliquely from lateral to medial
• On the left side - the RLN loops around the aortic arch and ascends more medially in the tracheoesophageal groove
• The RLN is identified either where it crosses the inferior thyroid artery or at its entry into the larynx at the cricothyroid joint
• IONM (intraoperative neuromonitoring) via vagal stimulation provides real-time electromyographic confirmation of nerve integrity
• The nerve is traced and kept under direct vision throughout dissection

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Step 8 - Preservation of the Parathyroid Glands

• There are typically 4 parathyroid glands (superior and inferior pairs), each the size of a lentil (~50 mg)
• The superior parathyroids lie posterior to the upper thyroid lobe near where the RLN enters the larynx
• The inferior parathyroids are more variable in position - often near the inferior thyroid pole or within the thyrothymic ligament
• Each gland is identified and carefully preserved with its blood supply (branches of the inferior thyroid artery)
• If a gland is inadvertently removed or devascularized, it is minced and auto-transplanted into the sternocleidomastoid or brachioradialis muscle

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Step 9 - Ligation of the Inferior Thyroid Artery

• The inferior thyroid artery is a branch of the thyrocervical trunk from the subclavian artery
• It is ligated at the level of the tracheoesophageal groove, distal to the parathyroid branches, to preserve parathyroid blood supply

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Step 10 - Division of Berry's Ligament

• Berry's (suspensory) ligament is the posterolateral attachment of the thyroid to the tracheal rings
• It is the final attachment of the thyroid lobe to the trachea
• The RLN often passes within or immediately adjacent to Berry's ligament - this is the highest-risk point for nerve injury during dissection
• The ligament is carefully divided with fine scissors or energy device to release the lobe
• The freed lobe is now removed

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Step 11 - Hemostasis and Wound Closure

• Meticulous hemostasis is achieved with bipolar diathermy or energy-based devices (e.g., LigaSure, Harmonic)
• The wound is irrigated and inspected
• A drain (closed suction) may be placed if there is concern for ooze or in cases with large dead space - though routine drainage is not universally required
• The strap muscles are re-approximated with absorbable sutures in the midline
• The platysma is closed as a separate layer
• Skin is closed with subcuticular sutures or surgical glue for a cosmetically acceptable scar

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Key Structures at Risk

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Postoperative Care

• Monitor calcium (PTH within 1 hour of resection is most predictive of hypoparathyroidism)
• Calcium and vitamin D supplementation as needed
• Voice assessment before discharge
• Wound check at 1-2 weeks
• Thyroid hormone replacement after total thyroidectomy (levothyroxine)
• RAI ablation if indicated for differentiated thyroid cancer

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