Thyroid Disorders and Relevant Surgical Procedures

Disorders of the Thyroid Gland

Benign Diseases of the Thyroid

Clinical Features of These Conditions

1. Thyroid cancer: Smooth, rounded swelling in midline of the neck, particularly in children and young adults.

2. Thyroglossal cyst: Fistulous opening that discharges clear fluid or pus.

3. Ectopic thyroid: Symptomless swelling near the foramen caecum of the tongue.

4. Hashimoto's: Mild thyroid enlargement, can be euthyroid or hyperthyroid initially, progresses to hypothyroid. Predominantly affects females.

5. Graves' disease: Diffuse enlargement causing symptoms of hyperthyroidism like weight loss, heat intolerance.

6. De Quervain's: Tenderness and recurrent episodes, typically euthyroid but can be hyperthyroid during acute phases.

7. Riedel's: Very hard, woody goitre suspicious of a tumour with possible compression symptoms.

Hyperplastic and Metabolic Disorders

General Features of Hyperplastic Disorders

1. Generally diffuse thyroid enlargement, often with normal function tests.

2. Physiological causes can lead to goitre and potential hypothyroidism if not monitored and managed.

3. Endemic goitre results from environmental factors that can be addressed via dietary adjustments.

4. Monitoring and early detection are crucial in childhood developmental defects to prevent associated hypothyroidism.

Factors Contributing to Goitre Development

• Iodine deficiency

• Genetic predisposition

• Environmental factors

• Hormonal imbalances

• Autoimmune diseases

Symptoms of Hyperthyroidism

1. Weight loss

2. Heat intolerance

3. Palpitations

4. Insomnia

5. Tremor

Thyrotoxicosis Symptoms

Metabolic:

• Heat intolerance

• Increased appetite with weight loss

• Diarrhea

• Menorrhagia

Cardiovascular:

• Palpitations

• Tachycardia

• Atrial Fibrillation

Neuropsychiatric:

• Hyperkinesis

• Insomnia

• Tremor

Ocular:

• Exophthalmos

Cutaneous:

• Pretibial myxedema

Compression Effects:

• A bulky goitre can lead to dysphagia and dyspnea.

Diagnosis of Thyroid Nodules

1. Ultrasound: To assess morphology of nodules.

2. Thyroid function tests: To assess hormone production.

3. Radioisotope Scanning: Useful for functional assessments.

4. CT Scanning: If malignancy is suspected.

5. MRI: To evaluate possible retrosternal extension.

6. Fine Needle Aspiration Cytology (FNAC): - For cytological analysis of nodules.

   • Distinguishes between benign and malignant nodules, guiding treatment decisions.

   • Minimally invasive, can be done without general anesthesia.

Effects of Parathyroid Hormone (PTH)

1. Increases osteoclastic activity: Facilitates bone metabolism, elevating plasma calcium levels.

2. Enhances renal tubular reabsorption of calcium: Reduces renal calcium loss.

3. Diminishes reabsorption of phosphate: Affects bone mineralization.

4. Promotes calcium absorption from the intestine: Enhances calcium availability from diet.

Hyperparathyroidism Causes:

• Single parathyroid adenoma

• Hyperplasia of all parathyroid glands

• Parathyroid carcinoma

• Genetic mutations

• Vitamin D deficiency

Signs:

• Muscle cramps

• Tetany

• Paraesthesia

• Chvostek’s sign

• Trousseau’s sign

Indications for Parathyroid Surgery

• Primary hyperparathyroidism due to adenoma

• Hyperplasia of all glands

• Parathyroid carcinoma

• Secondary hyperparathyroidism with refractory hypercalcemia

• Tertiary hyperparathyroidism post-renal transplantation

Risks Associated with Surgery

• Permanent hypoparathyroidism after thyroidectomy can result in complications requiring calcium and vitamin D supplementation.

• Careful surgical technique and preoperative mapping of the parathyroid glands can help minimize risks.

Thyroid Cancer

Malignant Diseases of the Thyroid

Clinical Features

1. Papillary carcinoma: Firm thyroid lump, excellent prognosis with even local metastases.

2. Follicular carcinoma: Similar presentation to papillary but with older demographics and no clear cervical lymphatic spread.

3. Anaplastic carcinoma: Diffuse hard enlargement with possible tracheal involvement, very poor prognosis.

4. Medullary carcinoma: Hard lump often associated with MEN II syndrome.

Preoperative Preparation for Thyroid Surgery

1. Ensure euthyroid status with medication.

2. Administer Lugol's iodine to reduce vascularity of the gland.

3. Conduct preoperative laryngoscopy to evaluate vocal cord function.

4. Dietary adjustments to minimize thyroid hormone levels.

5. Psychological evaluation to ensure readiness for surgery.

Treatment for Hyperthyroidism

1. Anti-thyroid drugs

2. Radioactive iodide therapy

3. Surgical management - Aimed to remove enough tissue to prevent hyperthyroidism.

   • Avoid excessive removal to prevent hypothyroidism and be cautious of complications.

4. Beta-adrenergic blocking drugs

5. Lifestyle modifications

Subtotal Thyroidectomy

• Definition: Removing most of the thyroid while retaining a small portion.

• Goals include curing hyperthyroidism while preserving function.

• Emphasis on preserving recurrent laryngeal nerves to minimize post-op hypothyroidism.

Postoperative Care Following Thyroid Surgery

1. Monitor for signs of hypocalcemia.

2. Evaluate potential vocal cord paralysis.

3. Check thyroid hormone levels.

4. Provide calcium supplements if necessary.

5. Regular follow-up for monitoring recurrence of disease.

Inspection Techniques in Neck Surgery

• Position: Inspect the neck in an extended position.

• Check for wounds, scars, inflammations, tumors, lymph nodes, bronchial cysts, carotid glomus.

• Observe for dilated jugular veins indicating superior vena cava compression.

• Cape Edema: May indicate mediastinal tumors.

• Notably, thyroid swellings will rise and fall during swallowing.

Operative Technique of Thyroidectomy

1. Collar incision above the suprasternal notch.

2. Dissection down to suprasternal notch and up to thyroid cartilage.

3. Central incision between strap muscles.

4. Continue dissection, ligate middle thyroid vein.

5. Identify upper pole vessels for ligation.

6. Ligation of lower pole vessels.

7. Displace lateral lobe anteriorly and identify critical vascular and nerve structures.

8. Excise targeted portions while preserving key anatomical structures, if necessary.

Criteria for Total Thyroidectomy

1. Presence of malignancy within the gland.

2. Goitre causing compressive symptoms.

3. Multinodular goitre with suspicion of malignancy.

4. Patient preference after discussing risks and benefits.

5. Recurrent hyperthyroidism not controlled by other means.

Preservation of Parathyroid Glands

1. Prevent postoperative hypoparathyroidism which leads to hypocalcemia.

2. Maintain calcium homeostasis.

3. Reduced risk of permanent hypocalcemia from inadvertent damage during surgery.

4. Ensure uninterrupted production of parathyroid hormone (PTH).

Complications of Thyroidectomy

Intraoperative Complications

1. Uncontrollable hemorrhage from slipped ligature.

2. Recurrent laryngeal nerve damage: results in hoarseness or laryngeal obstruction requiring tracheostomy if bilateral.

3. Damage to adjacent structures (trachea, esophagus).

Early Postoperative Complications

• Major hemorrhage: requires emergency intervention.

• Mediastinal hemorrhage: presents with hypovolemic shock.

• Laryngeal edema: requires immediate intubation.

• Thyrotoxic crisis management: involves beta-blockade and emergency treatment.

Later Postoperative Complications

• Hypoparathyroidism: presents with muscle cramps and tetany.

• Unilateral recurrent laryngeal nerve damage: hoarseness affects voice quality.

• Long-term complications include hypothyroidism and recurrent thyrotoxicosis if insufficient tissue was removed.