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GOITRE: CLASSIFICATION AND MANAGEMENT

MS ENT University Examination Answer (20 Marks)

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DEFINITION

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CLASSIFICATION OF GOITRE

I. BASED ON THYROID FUNCTION (Clinical Classification)

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II. BASED ON PATHOLOGICAL/STRUCTURAL TYPE (Bailey & Love, Table 55.3)

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III. WHO GRADING OF GOITRE (for field surveys / epidemiology)

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IV. BASED ON EPIDEMIOLOGY

• Endemic goitre - affects >10% of a population in a defined geographical area, mainly due to iodine deficiency. Common in mountainous regions (Alps, Himalayas, Andes, Rocky Mountains, Derbyshire/Yorkshire in UK).
• Sporadic goitre - occurs outside endemic areas; often due to dyshormonogenesis, goitrogens, or autoimmune causes.

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V. BASED ON ANATOMICAL EXTENT

• Cervical goitre - confined to the neck
• Retrosternal (substernal) goitre - extends below the thoracic inlet into the mediastinum
• Plunging goitre - intermittently descends into the chest with valsalva; returns on swallowing
• Wandering goitre - rare; loses all connection with the cervical gland

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AETIOLOGY OF SIMPLE GOITRE

1. Iodine deficiency - most important in endemic goitre; daily requirement ~0.1-0.15 mg iodine. Iodine-poor areas include mountainous ranges and areas with calcium-rich limestone soil (goitrogenic effect).
2. TSH stimulation - chronic low circulating thyroid hormones stimulate TSH secretion, driving thyroid follicular cell proliferation.
3. Dyshormonogenesis - enzyme deficiencies (often genetic) impairing thyroid hormone synthesis, causing TSH elevation and gland enlargement.
4. Goitrogens - dietary (cassava, brassica family - cabbage, turnips), drugs (lithium, amiodarone, propylthiouracil, carbimazole), excess iodine (Wolff-Chaikoff effect).
5. Immunoglobulins and growth factors - heterogeneous structural response leading to characteristic nodularity; certain clones of cells are particularly sensitive to growth stimulation, explaining nodule formation.

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CLINICAL FEATURES

• Neck swelling - moves up on swallowing (key sign: attached to trachea or thyroid)
• Pressure symptoms: dysphagia, stridor, dyspnoea, hoarseness (RLN compression/invasion)
• Features of hypo/hyperthyroidism depending on type
• Pemberton's sign - elevation of both arms causes facial flushing/venous engorgement/stridor (retrosternal goitre)

• Cervical swelling moving on deglutition
• Tracheal deviation
• Retrosternal dullness
• Features of toxicity (tremor, exophthalmos, tachycardia) if toxic goitre
• Vocal cord assessment on laryngoscopy

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INVESTIGATIONS

1. Thyroid Function Tests (TFT)

• TSH (most sensitive screening test), Free T3, Free T4
• Exclude hypo/hyperthyroidism

2. Thyroid Antibodies

• Anti-TPO, Anti-thyroglobulin - differentiate autoimmune thyroiditis from simple goitre

3. Ultrasonography (USG)

• Gold standard for nodule assessment when performed by trained operator
• Determines: number, size, echotexture, cystic vs. solid, vascularity (Doppler), suspicious features (microcalcifications, taller-than-wide shape, ill-defined margins, hypoechogenicity)
• Assesses: extent of enlargement, retrosternal extension, tracheal deviation/narrowing
• Multiple isoechoic nodules with cystic change in both lobes = almost certainly benign MNG
• Outperforms CT and MRI for nodule characterisation

4. Fine Needle Aspiration Cytology (FNAC)

• Required only for nodules demonstrating suspicious ultrasonographic features
• Must be done under ultrasound guidance to target the correct nodule
• UK/British reporting (Thy classification):

5. CT Scan of Neck and Chest

• Indicated when swallowing/breathing symptoms are present
• Best for assessing: tracheal deviation, oesophageal compression, retrosternal extension, extent of disease
• Note: CT arms-up position may underestimate retrosternal extent - surgeon must be aware of patient positioning during interpretation

6. Flexible Laryngoscopy

• Preoperative assessment of vocal cord mobility (mandatory before thyroid surgery)
• Unilateral cord palsy + ipsilateral suspicious nodule = highly suggestive of malignancy

7. Radioactive Iodine Scan (99mTc or 131I)

• Hot, warm, or cold nodule assessment
• Cold nodule has higher risk of malignancy (~10-15%)
• Useful for toxic nodules

8. Serum Calcitonin

• Elevated in medullary thyroid carcinoma (MTC)
• Some guidelines recommend routine testing for all thyroid nodules

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MANAGEMENT

A. MEDICAL MANAGEMENT

• Iodised salt - has strikingly reduced the incidence of endemic goitre worldwide
• Potassium iodide supplementation

• In early hyperplastic goitre: L-thyroxine 0.15-0.2 mg/day for a few months may cause regression
• The nodular stage is largely irreversible - thyroxine has limited benefit in MNG
• More than half of benign nodules regress in size over 10 years (spontaneous regression)
• Caution: TSH suppression risks osteoporosis and atrial fibrillation, especially in elderly

• Alternative to surgery in toxic MNG or Graves' disease in patients unfit for surgery
• May also reduce size of non-toxic goitre by ~30-40%
• Contraindicated in pregnancy, suspected malignancy, very large goitres causing compression
• Risk of radiation thyroiditis, transient worsening of symptoms

• Stop offending drug if possible; substitute alternative medications

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B. SURGICAL MANAGEMENT

Indications for Surgery in Goitre

1. Suspected malignancy - FNAC Thy4 or Thy5, suspicious USG features, dominant/rapidly growing nodule
2. Follicular neoplasm (Thy3) - all should be excised as cytology cannot distinguish follicular adenoma from carcinoma
3. Pressure symptoms - dysphagia, stridor, dyspnoea not responding to medical therapy
4. Retrosternal/substernal extension - especially if symptomatic or in young patients
5. Toxic goitre - Graves' disease or toxic MNG unresponsive or unsuitable for medical/radioiodine treatment
6. Cosmetic disfigurement - if significant
7. Patient preference after adequate counselling

Contraindications/Relative Caution

• Elderly patients with incidentally discovered retrosternal goitre - may observe rather than treat prophylactically

Types of Thyroid Surgery

Surgery for Specific Conditions

• Near-total or total thyroidectomy preferred
• Reduces recurrence risk vs. subtotal approach
• Total thyroidectomy: immediate control of toxicity, 100% risk of hypothyroidism (thyroid replacement mandatory), 5% permanent hypoparathyroidism
• Subtotal thyroidectomy: variable return to euthyroid (up to 12 months), lifelong risk of recurrence (~5%) and late failure (up to 100% at 30 years)

• Surgery after achieving euthyroid state with antithyroid drugs (carbimazole/PTU)
• Total vs. subtotal thyroidectomy comparison (see table above)
• Total thyroidectomy preferred in most modern practice

• Vast majority (>95%) can be removed via transcervical (collar) incision
• Blood supply originates in the neck - ligate, divide, then use gentle blunt finger dissection to free mediastinal component
• Division of isthmus may facilitate delivery
• Sternotomy required for: malignant disease, previous thyroid operations, no cervical thyroid tissue, goitre diameter exceeding thoracic inlet, posterior mediastinal extension
• Joint planning with thoracic surgery in high-risk cases

Complications of Thyroid Surgery

• Haemorrhage/haematoma - can cause acute airway compromise (emergency: open wound at bedside)
• RLN injury - unilateral: hoarseness; bilateral: stridor, emergency tracheostomy
• Wound infection

• Hypocalcaemia (hypoparathyroidism) - tetany, Chvostek's/Trousseau's signs; treat with IV calcium gluconate acutely, then oral calcium/vitamin D
• Seroma

• Hypothyroidism (requires lifelong thyroxine replacement)
• Recurrent hyperthyroidism (after subtotal resection)
• Keloid scar
• Superior laryngeal nerve (external branch) injury - loss of high-pitched voice, fatigue of voice

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RETROSTERNAL GOITRE - SPECIAL NOTE (Common ENT Exam Topic)

• Defined as thyroid enlargement that extends below the thoracic inlet into the superior mediastinum
• Incidence: <1% of all goitres have significant intrathoracic extension
• Blood supply: from superior and inferior thyroid arteries in the neck (not from mediastinal vessels) - this is why transcervical removal is almost always possible
• Symptoms: dysphagia, dyspnoea, stridor, facial oedema, SVCO features
• Pemberton's sign - raised arms causes venous obstruction and facial flushing
• Investigation: CT scan (defines extent, tracheal compression, vascular relationships)
• Management: surgery via collar incision; sternotomy reserved for special situations (see above)

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COMPLICATIONS OF UNTREATED GOITRE

1. Tracheal obstruction - lateral displacement or anteroposterior compression; retrosternal extension impacting thoracic inlet
2. Acute respiratory obstruction - haemorrhage into a nodule causing sudden enlargement
3. Secondary thyrotoxicosis - transient hyperthyroid episodes occur in up to 30% of MNG patients
4. Carcinoma - increased incidence (usually follicular) in endemic areas and longstanding nodular goitres. Dominant or rapidly growing nodules must always be aspirated
5. Dysphagia - oesophageal compression
6. SVCO - superior vena cava obstruction (retrosternal goitre)
7. Recurrent laryngeal nerve palsy

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SUMMARY TABLE FOR QUICK REVISION

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• Bailey and Love's Short Practice of Surgery, 28th Edition (Chapter 55: Thyroid)
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Vol. 1
• Cummings Otolaryngology Head and Neck Surgery, 7th Edition
• Sabiston Textbook of Surgery