In a patient with a large thyroid nodule (goiter) presenting with cough and throat discomfort, what is the most likely cause and how should it be evaluated and managed?

Large Thyroid Nodule Causing Cough and Throat Discomfort

The most likely cause is direct mechanical compression of the trachea by the goiter, and you should obtain a CT scan of the neck with contrast to assess the degree of tracheal compression and plan definitive surgical management with total thyroidectomy. 1

Primary Mechanism of Symptoms

The cough and throat discomfort are caused by mechanical compression and irritation of the trachea from the enlarged thyroid nodule. 2 Large goiters can cause:

• Tracheal compression and deviation leading to cough, dyspnea, and orthopnea 1, 3
• Direct local irritation of airway structures 2
• Extrinsic compression that may progress to tracheomalacia in long-standing cases 2

Less commonly, thyroid-related cough can result from inflammatory thyroiditis causing local irritation, though this typically improves with treatment of the underlying thyroid inflammation. 2

Essential Diagnostic Workup

Imaging Protocol

• CT scan of the neck with contrast is mandatory for any large thyroid nodule causing compressive symptoms 1, 3

  • CT is superior to ultrasound for determining the precise degree of tracheal compression 1, 3
  • CT identifies substernal or retrosternal extension that ultrasound cannot adequately visualize 1, 4, 3
  • CT assesses invasion of great vessels and upper aerodigestive tract structures 1
  • CT has less respiratory motion artifact than MRI, making it the preferred modality 3

• Ultrasound should be performed initially to confirm thyroid origin, characterize nodule morphology, and identify nodules requiring biopsy, but recognize its significant limitations in evaluating tracheal compression 1, 4

Functional Assessment

• Evaluate vocal cord mobility preoperatively using fiberoptic laryngoscopy, mirror indirect laryngoscopy, or ultrasound to identify baseline function 1, 4
• Assess for specific compression symptoms: dyspnea, orthopnea, stridor, obstructive sleep apnea, dysphagia, and dysphonia 1, 4
• Measure serum TSH to assess thyroid functional status 5, 6
• Evaluate cervical lymph nodes by ultrasound when thyroid nodules are identified 4

Tissue Diagnosis

• Fine-needle aspiration biopsy (FNAB) remains the preferred method for cytological diagnosis 4
• Core needle biopsy should be reserved for cases where FNAB is nondiagnostic, as it carries higher hemorrhage risk 4

Management Algorithm

Indications for Surgery (Total Thyroidectomy)

Proceed with total thyroidectomy for: 1

• Any compressive nodule causing tracheal deviation
• Suspected malignancy on cytology
• Progressive growth with increasing symptoms
• Symptomatic patients with dysphagia, choking sensation, or airway obstruction 5, 7

Critical surgical considerations:

• The surgeon must identify the recurrent laryngeal nerve during thyroidectomy to optimize voice outcomes and reduce injury risk 1, 3
• Large, long-standing goiters may cause tracheal deviation that complicates intubation, requiring careful perioperative airway management 1, 3
• Removal of large goiters may cause collapse of an already tracheomalacic airway 3

Alternative: Thermal Ablation

Thermal ablation may be considered only when ALL of the following criteria are met: 1, 4

• The nodule is definitively benign
• The patient refuses surgery OR has medical contraindications to surgery
• The patient is treated at an experienced center

Critical contraindications to thermal ablation include: 1, 4

• Any uncertainty about malignancy potential
• Diffuse sclerosing papillary carcinoma
• Malignancies other than papillary thyroid carcinoma

Critical Pitfalls to Avoid

• Do not delay surgery in patients with tracheal deviation and mediastinal extension, as acute airway distress can develop suddenly and require emergency intervention 1, 8
• Do not rely on ultrasound alone for surgical planning when tracheal compression is present—CT is essential 1, 3
• Do not assume benign goiters are safe to observe if they cause any degree of tracheal compression, especially with substernal extension, as sudden growth can seriously compromise respiration 9, 8
• Elective surgery should be performed at the first sign of tracheal compression, particularly if mediastinal extension is present, to prevent acute airway emergencies 8

Post-Treatment Monitoring

After Total Thyroidectomy

• Monitor for hypoparathyroidism 1
• Monitor for recurrent laryngeal nerve injury 1
• Monitor need for levothyroxine replacement 1

After Thermal Ablation

• Follow-up schedule includes assessments at 1,3,6, and 12 months during the first year 1, 4
• Ultrasound and contrast-enhanced ultrasound to assess ablation zone 1, 4