Total Thyroidectomy

Definition and Nomenclature

• Sabiston Textbook of Surgery, p. 1522

Indications

1. Thyroid cancer - differentiated, medullary, or anaplastic thyroid carcinoma
2. Hyperthyroidism - Graves disease, toxic multinodular goiter, when nonsurgical management has failed or is not preferred
3. Goiter - with or without local compressive symptoms (tracheal compression, dysphagia, dyspnea)
4. Thyroid nodules - indeterminate or suspicious on FNA biopsy

• Current Surgical Therapy 14e, p. 898; Sabiston Textbook of Surgery, p. 1522

Surgical Anatomy

• Each lobe is fed by two arteries: the superior thyroid artery (branch of external carotid) and the inferior thyroid artery (from thyrocervical trunk)
• Venous drainage via three named veins: superior, middle, and inferior thyroid veins

• External branch of the superior laryngeal nerve (EBSLN): innervates the cricothyroid muscle, controlling high-pitch voice projection. It travels close to the superior thyroid artery. The Cernea classification describes its relationship to the superior pole:

• Type 1: crosses > 1 cm above the superior pole (safest)
• Type 2A: crosses within 1 cm above the superior pole
• Type 2B: crosses below the superior border of the superior pole (highest risk)
• Recurrent laryngeal nerve (RLN):
  • Left RLN: loops around the aortic arch, ascends in the tracheoesophageal groove
  • Right RLN: loops around the subclavian artery, ascends more laterally
  • A non-recurrent inferior laryngeal nerve (prevalence ~0.5%) occurs with an aberrant retro-esophageal right subclavian artery - it lies in a near-transverse trajectory and must be identified preoperatively

• Two glands per side (superior and inferior), classically posterior to the thyroid
• Superior glands are more predictable, lying within 2-5 mm of the RLN
• Inferior glands are more variable, on average 7-10 mm from the RLN
• Ectopic glands occur in ~15% of patients (retroesophageal, intrathyroidal, or in the thyro-thymic ligament/mediastinum)
• Current Surgical Therapy 14e, p. 898-899

Preoperative Preparation

• Biochemical assessment: TFTs (TSH, free T4), serum calcium (especially in MEN2A)
• Imaging: Neck ultrasound; CT for substernal extension or airway assessment
• FNA biopsy: for nodular or malignant disease
• For hyperthyroidism: render the patient euthyroid preoperatively with antithyroid drugs ± beta-blockers; Lugol's iodine solution or SSKI may be added within 10 days of surgery for Graves disease to reduce gland vascularity
• Voice and laryngeal assessment:
  • All patients: noninvasive voice history and assessment
  • Selective laryngoscopy for: prior voice changes, prior cervical surgery, posterior extrathyroidal extension, or bulky nodal metastases
  • Preoperative vocal cord dysfunction found in up to 3.5% with benign disease and up to 8% with cancer; notably up to 20% of paralyzed cords are associated with a normal voice
  • Transcutaneous laryngeal ultrasound is emerging as a noninvasive alternative (sensitivity/specificity 93-100%/97-100%)
• Sabiston Textbook of Surgery, p. 1523-1524

Anesthesia and Positioning

• General endotracheal anesthesia (most cases)
• If intraoperative nerve monitoring (IONM) planned: specialized neuromonitoring ETT with vocal cord contact electrodes; muscle relaxants are contraindicated
• Position: supine, both arms tucked, back raised ~20-30 degrees (reverse Trendelenburg), neck extended with a shoulder roll
• Excessive extension is uncomfortable postoperatively; inadequate extension crowds the field
• Total IV anesthesia (TIVA) may reduce coughing and improve recovery quality
• Local anesthesia with cervical plexus blocks is described but uncommon
• Scott-Brown's Otorhinolaryngology, p. 1060-1067; Sabiston Textbook of Surgery, p. 1524

Operative Technique

Incision and Exposure

• Transverse collar incision along Langer's lines, typically 2-3 cm above the clavicular heads
• Carried through the platysma; subplatysmal flaps raised inferiorly to the clavicles and superiorly to the thyroid cartilage
• Strap muscles (sternohyoid, sternothyroid) lifted off the thyroid capsule in the midline along avascular planes
• Middle thyroid vein exposed and ligated between thyroid and IJV
• For large/firm glands: sternothyroid muscle may be divided high (near thyroid cartilage insertion) to improve lateral exposure; preserve the ansa cervicalis

Superior Pole Dissection

• Develop the avascular cricothyroid space (space of Reeve) between the superior pole and cricothyroid muscle
• Isolate the superior thyroid artery with closed-tip blunt dissection
• Identify the EBSLN (visually or with nerve monitor) before ligation
• Divide the superior pedicle as close to the gland as possible to protect the EBSLN

Inferior Pole Dissection

• Retract inferior pole superiorly; ligate inferior thyroid vein branches close to the gland
• Avoid straying deep and lateral (risks injury to the parathyroids and RLN)

RLN Identification and Parathyroid Preservation

• The RLN is at greatest risk at: (1) the ligament of Berry, (2) during ligation of branches of the inferior thyroid artery, and (3) at the thoracic inlet
• The nerve should be identified and traced along its entire course
• IONM allows direct or vagal stimulation-based monitoring of RLN integrity
• Superior parathyroid glands: posterior to the RLN plane; inferior glands: anterior
• Any devascularized or inadvertently removed parathyroid tissue confirmed by frozen section or intraoperative PTH aspiration should be minced and autotransplanted into the sternocleidomastoid muscle

Isthmus Division

• Dissection extended under the isthmus; divided so that the isthmus (and pyramidal lobe if present) is included with the specimen
• Current Surgical Therapy 14e, p. 899-900; Sabiston Textbook of Surgery, p. 1525-1527

Minimally Invasive Approaches

• Transaxillary thyroidectomy: remote access; avoids a neck scar
• Transoral thyroidectomy: vestibular approach; no visible scar
• Robotic thyroidectomy: extends the reach and dexterity of minimally invasive approaches
• These offer cosmetic advantages; fundamental surgical steps remain the same

Postoperative Care

• Outpatient thyroidectomy is appropriate for selected patients who: (1) live within driving distance of the hospital, (2) have reliable adult support at home for 24 hours, (3) have no significant perioperative comorbidities or anticoagulant use
• The majority of neck hematomas occur within the first 6 hours; standard observation was historically overnight but outpatient management is now evidence-supported for low-risk cases
• Thyroid hormone replacement (levothyroxine) is required after total thyroidectomy; started postoperatively
• Calcium/calcitriol supplementation: many high-volume centers use prophylactic calcium ± calcitriol after total thyroidectomy, especially in high-risk groups (Graves disease, pediatric patients)

Complications

1. Recurrent Laryngeal Nerve Injury

• Temporary injury: 4-10% of cases
• Permanent injury: 0.5-2% (up to fourfold higher in children)
• Unilateral: hoarse/breathy voice, vocal fatigue, dysphagia, aspiration
• Bilateral: midline vocal cord positioning → airway compromise → may need tracheostomy
• Risk factors: low surgeon volume, reoperative surgery, extensive malignancy, Graves disease, large substernal goiter

2. Hypoparathyroidism

• Most common complication of thyroid surgery
• Temporary: up to 5-15% (resolves within 6 months in most)
• Permanent: 1-3%
• Manifests as symptomatic hypocalcemia (tetany, perioral tingling, Chvostek's/Trousseau's signs)
• Risk factors: bilateral neck exploration, central neck dissection, reoperative surgery, Graves disease, pediatric age
• Near-infrared parathyroid autofluorescence shows promise for intraoperative identification but current data show mixed results

3. Postoperative Neck Hematoma

• Incidence: 0.1-1.1%
• The primary danger is tracheal compression causing rapid airway compromise (not blood loss)
• Presents with: pain, incision oozing, ecchymosis, firm neck swelling, and potentially stridor
• Requires immediate return to the operating room for hematoma evacuation
• Risk factors: male sex, advanced age, bilateral operation, Graves disease, anticoagulant use

4. EBSLN Injury

• Causes: vocal fatigue, decreased high-pitch ability, reduced voice projection
• Rates estimated at 2.5-28% (wide range due to diagnostic difficulty; laryngoscopy often normal; confirmed by EMG)
• Sabiston Textbook of Surgery, p. 1527-1529

Surgeon Volume and Outcomes

• Surgeon experience is a well-established, modifiable determinant of outcomes
• Higher-volume surgeons have fewer complications, shorter stays, and lower costs
• A study of 16,954 patients showed outcomes improved with increasing volume up to a threshold of 26 total thyroidectomies per year on restricted cubic spline analysis
• Sabiston Textbook of Surgery, p. 1522