Thyroid Surgery
Thyroid 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:
- Haematoma (1-2%): 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 |