Thyroid Surgery
Chapter notes (PDF)PDFThyroid surgery (thyroidectomy) is performed for malignancy, compressive goitre, hyperthyroidism refractory to medical therapy, and cosmesis. Key complications include recurrent laryngeal nerve injury and hypoparathyroidism.
Key Facts
- Indications: Thyroid cancer, compressive symptoms (dysphagia, stridor), retrosternal goitre, failed medical management of hyperthyroidism, cosmesis, suspicious/indeterminate cytology
- Recurrent laryngeal nerve (RLN) injury: Most feared complication; unilateral = hoarse voice (~1-2%); bilateral = stridor/airway compromise - EMERGENCY
- Hypoparathyroidism: Transient ~20-30%; permanent ~1-2%; presents with hypocalcaemia (perioral tingling, Chvostek's/Trousseau's signs)
- Post-operative calcium monitoring: All patients require serial calcium checks (6-hourly for 24-48 hours)
- Thyroid storm can be triggered peri-operatively in uncontrolled hyperthyroidism - ensure euthyroid pre-operatively
- Haematoma: Expanding neck haematoma → airway compromise; emergency - open wound at bedside, evacuate clot
- Types: Total thyroidectomy (cancer, bilateral disease), hemithyroidectomy/lobectomy (unilateral disease, diagnostic), subtotal (Graves' - less common now)
- Pre-operative laryngoscopy: Assess vocal cord function before surgery - medicolegal requirement
Overview
Key Facts
Thyroid surgery requires detailed anatomical knowledge and meticulous technique. Understanding the complications and their management is essential for all surgical trainees.
Epidemiology
~10,000 thyroidectomies performed annually in England. Most common indication: Thyroid cancer (~30%), followed by multinodular goitre (~25%) and hyperthyroidism (~15%).
Aetiology
Indications for thyroid surgery:
- Confirmed or suspected thyroid malignancy (Thy4/Thy5 on cytology)
- Compressive goitre (dysphagia, dyspnoea, stridor)
- Retrosternal goitre
- Toxic multinodular goitre or Graves' disease (failed medical/radioiodine)
- Cosmesis
Pathophysiology
Anatomical considerations:
- Recurrent laryngeal nerve: Runs in tracheo-oesophageal groove; left hooks under aortic arch; right hooks under subclavian artery; enters larynx behind cricothyroid joint
- External branch of SLN: Runs with superior thyroid artery; injury → weak, monotonous voice (difficulty projecting)
- Parathyroid glands: Usually 4 glands; superior (from 4th pharyngeal pouch) more constant position; inferior (from 3rd pouch) more variable
- Berry's ligament: Posterior suspensory ligament - RLN at highest risk at this point
Clinical Presentation
Pre-operative Assessment
- TFTs: Ensure euthyroid (especially in hyperthyroidism - carbimazole/propranolol pre-operatively)
- Vocal cord assessment: Flexible nasendoscopy - document pre-operative function
- Imaging: US neck, CT if retrosternal extension suspected
- Cytology/histology: FNA result (Thy1-5 classification)
- Calcium/PTH: Baseline
Post-operative Complications
Early:
Expanding neck swelling
airway compromise
EMERGENCY
- Hypocalcaemia: Usually within 24-48 hours; perioral tingling, tetany
- RLN injury: Hoarseness (unilateral); stridor (bilateral)
- SLN injury: Weak voice, difficulty projecting
- Wound infection: Uncommon
Late:
- Permanent hypoparathyroidism (~1-2%): Lifelong calcium/alfacalcidol
- Hypothyroidism: After total thyroidectomy - requires lifelong levothyroxine
- Keloid scar
Red Flags
- Expanding neck swelling post-op - haematoma, open at bedside
- Stridor post-op - bilateral RLN injury or oedema; assess airway urgently
- Symptomatic hypocalcaemia - IV calcium gluconate 10mL 10% over 10 minutes
Differential Diagnosis
| Complication | Presentation | Immediate Action |
|---|---|---|
| Haematoma | Expanding neck, stridor, dyspnoea | Open wound at bedside, evacuate clot, return to theatre |
| Bilateral RLN palsy | Stridor, respiratory distress post-op | Re-intubation, ENT review, may need tracheostomy |
| Unilateral RLN palsy | Hoarseness | ENT review, speech therapy, usually recovers |
| Hypocalcaemia | Perioral tingling, carpopedal spasm | IV calcium gluconate, oral calcium + alfacalcidol |
| Thyroid storm | Fever, tachycardia, agitation peri-op | IV propranolol, Lugol's iodine, hydrocortisone, dantrolene |
Diagnosis / Investigation
Pre-operative
- TFTs: Confirm euthyroid status
- Calcium, PTH: Baseline
- US neck: Nodule characteristics, lymph nodes
- FNA cytology: Thy classification (1-5)
- CT neck/thorax: If retrosternal extension
- Flexible nasendoscopy: Vocal cord assessment
Post-operative
- Serial calcium: Every 6 hours for 24-48 hours; corrected calcium
- PTH: Measured at 4-6 hours post-op; predicts hypocalcaemia
- Vocal assessment: Voice quality; formal laryngoscopy if concerns
- Histology: Final pathology for cancer staging
Management
Haematoma (Emergency)
- Expanding neck haematoma = airway emergency
- At the bedside: Remove clips/sutures, evacuate clot, call for help
- Return to theatre: Definitive haemostasis
- Keep skin closure trolley at bedside for all thyroid patients
Hypocalcaemia
- Symptomatic: IV calcium gluconate 10mL 10% over 10 minutes (can repeat)
- Ongoing replacement: Oral calcium carbonate 1-2g TDS + alfacalcidol 0.25-1mcg OD
- Monitor calcium daily until stable
- Most transient cases resolve within 1-6 months
- Permanent: Lifelong calcium + vitamin D analogues
RLN Injury
- Unilateral: Hoarse voice; ENT review; speech therapy; most recover within 6-12 months
- Bilateral: Stridor - may need re-intubation or tracheostomy; ENT urgent review
- Medicolegal: Pre-op laryngoscopy documentation is essential
Post-thyroidectomy Thyroid Replacement
- Total thyroidectomy: Levothyroxine started immediately (1.6 mcg/kg/day)
- TSH suppression: For differentiated thyroid cancer - TSH target <0.1 mU/L (initial)
- Hemithyroidectomy: ~30% will need levothyroxine; monitor TFTs at 6 weeks
Referral Criteria
- Suspected thyroid malignancy - MDT
- Compressive goitre - surgical referral
- Failed medical management of hyperthyroidism - endocrine surgeon
Prognosis
- Overall mortality of thyroid surgery: <0.1%
- RLN injury: Temporary ~5-8%; permanent ~1-2%
- Hypoparathyroidism: Temporary ~20-30%; permanent ~1-2%
- Haematoma: ~1-2% - potentially life-threatening if unrecognised
- Thyroid cancer: Excellent prognosis for differentiated cancer (papillary/follicular) - >95% 10-year survival
- Higher-volume surgeons have lower complication rates
Other Relevant Information
Thy Classification (FNA Cytology)
| Category | Interpretation | Action |
|---|---|---|
| Thy1 | Non-diagnostic | Repeat FNA |
| Thy2 | Benign | Reassure/follow-up |
| Thy3a | Atypical (equivocal) | Repeat FNA or diagnostic lobectomy |
| Thy3f | Follicular neoplasm | Diagnostic lobectomy |
| Thy4 | Suspicious of malignancy | Surgery |
| Thy5 | Malignant | Surgery |