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Thyroid Surgery - NEET PG Complete Guide

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1. HISTORICAL HIGH-YIELD POINTS

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2. INDICATIONS FOR THYROIDECTOMY

1. Hyperthyroidism - when nonsurgical management has failed or is not preferred
2. Goiter - with or without compressive symptoms (dysphagia, dyspnea, stridor)
3. Cancer / nodules - thyroid malignancy or suspicious nodules

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3. TYPES OF THYROID SURGERY (VERY HIGH-YIELD)

When to use which operation:

• Thyroid cancer - total thyroidectomy (facilitates radioiodine ablation and surveillance)
• Graves' disease - total or near-total thyroidectomy (ATA guideline); Dunhill operation was classic
• Toxic nodule / MNG - lobectomy or total thyroidectomy depending on extent
• Low-risk DTC (< 4 cm, no extrathyroidal extension, no nodes) - lobectomy acceptable per ATA 2015 guidelines
• Isthmus papillary cancer - isthmusectomy (selected cases)

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4. PREOPERATIVE PREPARATION

• Biochemical - TFTs, serum calcium, vitamin D
• Imaging - neck ultrasound (mandatory); CT neck/chest if substernal extension suspected
• FNA - for all suspicious nodules as indicated
• Laryngoscopy - check vocal cord function preoperatively if: prior neck/upper chest surgery, voice changes, known posterior extrathyroidal extension, extensive central nodal disease
• Render euthyroid before surgery:
  • Antithyroid drugs (carbimazole/PTU) + beta-blockers
  • Lugol's iodine / SSKI given 10 days pre-op for Graves' disease - reduces thyroid vascularity and bleeding

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5. SURGICAL TECHNIQUE - STEP BY STEP

Patient Positioning

• Supine, arms tucked
• Sandbag/roll between scapulae to extend the neck - brings thyroid anteriorly (especially helpful for substernal goiters)
• Head on foam/gel ring; back raised ~20 degrees
• Neck extended but not hyperextended (prevents postoperative posterior neck pain)

Incision

• Kocher collar incision - transverse, 3-5 cm (up to longer if needed), placed 1 cm below the cricoid cartilage in or parallel to a natural skin crease
• Extended through platysma
• Subplatysmal flaps raised:
  • Superiorly to thyroid cartilage
  • Inferiorly to suprasternal notch

Exposure

• Strap muscles divided in midline (linea alba of neck)
• Sternohyoid separated from sternothyroid by blunt dissection
• Strap muscles rarely need to be divided transversely - if needed, cut high to preserve ansa cervicalis innervation
• If tumor invades strap muscles - resect en bloc
• Middle thyroid veins ligated and divided first (allows medial retraction of lobe)

Superior Pole Dissection

• Thyroid retracted inferiorly and medially first
• Superior pole vessels individually ligated close to the thyroid (skeletonize them on the gland)
• Critical point: avoid the External Branch of Superior Laryngeal Nerve (EBSLN) - it runs along the cricothyroid muscle just medial to the superior pole and can be injured if ligation is done far from thyroid
• EBSLN injury: loss of high-pitched phonation (singer's nerve) - Cernea classification

Identification of RLN and Parathyroids

• Thyroid retracted anteromedially
• RLN found in tracheoesophageal groove
• Parathyroids usually within 1 cm of the crossing of the inferior thyroid artery and RLN
• Inferior thyroid artery ligated at branches close to thyroid surface (extracapsular dissection) - to preserve parathyroid blood supply

Ligament of Berry

• Most dangerous zone for RLN - the nerve is closest to the thyroid here and often passes through this ligament
• Do not use electrocautery near the RLN in this area
• Control bleeding with gentle pressure, then carefully ligate

Division

• If lobectomy: divide isthmus lateral to midline to minimize future hypertrophy of remnant
• Pyramidal lobe present in up to 80% of patients; must be dissected cephalad (can reach hyoid bone) until tissue tapers into fibrous band

Closure

• Strap muscles reapproximated with small gap at lower midline (allows blood to exit deeper space)
• Platysma closed with absorbable sutures
• Skin - fine subcuticular suture (cosmetic)
• No drain needed in majority of cases
• Valsalva maneuver by anesthesia to confirm hemostasis before closing

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6. KEY SURGICAL ANATOMY (EXAM FAVORITE)

Recurrent Laryngeal Nerve (RLN)

• RLN runs deep to inferior thyroid artery in most cases (may be anterior to it - variable)
• Best identified at level of cricoid cartilage
• ATA 2015: visual identification of RLN is strongly recommended in ALL cases
• Intraoperative neuromonitoring (IONM) may reduce transient RLN injury (especially in high-risk cases); does not reduce permanent injury significantly

External Branch of Superior Laryngeal Nerve (EBSLN)

• Supplies cricothyroid muscle (only intrinsic laryngeal muscle NOT supplied by RLN)
• Injury: loss of ability to raise pitch - damages professional singers
• Cernea Type 2A and 2B are at high risk during superior pole dissection
• Protected by: ligating superior pole vessels close to thyroid capsule

Parathyroid Glands

• Superior parathyroids - more constant in position, near superior pole, posterior surface of thyroid
• Inferior parathyroids - more variable, near inferior pole, anterior to RLN
• Blood supply: branches of inferior thyroid artery (primarily)
• Identification: yellowish-tan, soft; bleeds when cut (unlike fat which does not)
• If inadvertently removed: confirm on frozen section + autotransplant into sternocleidomastoid

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7. COMPLICATIONS - VERY HIGH YIELD

A. Recurrent Laryngeal Nerve Injury

• Incidence: ~1-2% permanent in experienced hands
• Management of unilateral permanent: voice therapy, medialization procedures (thyroplasty)

B. Hypoparathyroidism / Hypocalcemia

• Most common serious complication after total thyroidectomy
• Causes: devascularization, manipulation, or inadvertent removal of parathyroids
• Transient (most common) vs permanent (< 1-2%)
• Hungry Bone Syndrome - especially in hyperthyroid patients after total thyroidectomy: severe prolonged hypocalcemia despite normal PTH (high bone turnover absorbs calcium); associated low phosphate, low magnesium, high potassium

• Perioral tingling, fingertip numbness
• Chvostek's sign (tapping facial nerve - facial twitch)
• Trousseau's sign (BP cuff inflation - carpopedal spasm)
• Severe: tetany, laryngospasm, seizures

• Oral calcium + calcitriol supplementation
• Monitor serum calcium / intraoperative PTH post-closure
• Preoperative calcitriol in high-risk patients (Graves' disease, reoperative surgery)

C. Postoperative Neck Hematoma

• Incidence ~1%
• Presentation: neck swelling, pain, respiratory distress (compresses trachea)
• Emergency management: open the wound at bedside immediately to decompress, then return to OR for formal exploration
• Can be life-threatening due to airway compromise

D. Thyroid Storm (Thyrotoxic Crisis)

• Occurs in 1-5% of hospitalized thyrotoxic patients
• Triggered by: surgery (especially if patient not euthyroid), trauma, infection, cessation of antithyroid drugs
• Burch-Wartofsky scoring system (1993) - grades severity based on temperature, CNS, GI/hepatic, cardiovascular, precipitating event
• Treatment: PTU (blocks synthesis + peripheral conversion), beta-blockers, hydrocortisone, Lugol's iodine (after PTU), cooling, supportive care

E. External Branch SLN Injury

• Loss of high-pitched phonation, voice fatigue
• Missed on routine post-op voice assessment (cord moves normally)

F. Other Complications

• Tracheal injury (rare)
• Esophageal injury (rare)
• Chylous fistula (left-sided dissections, thoracic duct injury)
• Wound infection, seroma
• Hypothyroidism (expected after total thyroidectomy - treated with levothyroxine)

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8. SPECIFIC CLINICAL SCENARIOS

Graves' Disease Surgery

• Render euthyroid pre-op: carbimazole + propranolol
• Add Lugol's iodine for 10 days before surgery (Wolff-Chaikoff effect - reduces vascularity)
• Preferred operation: total or near-total thyroidectomy
• Higher risk of hypoparathyroidism (start prophylactic calcitriol)

Thyroid Cancer Surgery

• Papillary / Follicular (DTC): total thyroidectomy for tumors > 4 cm, bilateral disease, extrathyroidal extension, nodal disease; lobectomy acceptable for low-risk unifocal < 4 cm
• Medullary thyroid cancer: total thyroidectomy + central neck dissection (Level VI); check calcitonin and CEA; rule out pheochromocytoma before surgery (RET mutation, MEN2)
• Anaplastic: poor prognosis; surgery rarely curative; role is airway management

Substernal Goiter

• Usually extirpated via cervical approach (same Kocher incision)
• Median sternotomy or thoracotomy needed if: truly intrathoracic blood supply, tumor components, or unable to deliver via neck
• Higher risk of RLN injury (nerve distorted)

Minimally Invasive Thyroidectomy

• Mini-incision: 3 cm, no flap, deliver thyroid into wound
• Endoscopic approaches: axillary, anterior chest, breast - scar-free neck
• Transoral (through mouth) - newest approach
• Robotic assistance available for all remote-access approaches
• Benefits over open not clearly established for all patients

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9. NEET PG HIGH-YIELD QUICK FACTS

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10. POSTOPERATIVE FOLLOW-UP

• After total thyroidectomy: levothyroxine replacement (weight-based); serum calcium monitoring 1-2 days post-op; TSH suppression if cancer
• After lobectomy: thyroid function test at 6 weeks; ~15-20% will need levothyroxine if remaining lobe insufficient
• Thyroid cancer follow-up: serum thyroglobulin + neck ultrasound; radioiodine ablation if indicated (total thyroidectomy needed for RAI to work)
• Most patients discharged within 2-24 hours; return to normal activity within 1 week

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