What is the most common cause of respiratory distress associated with goiter?

Causes of Respiratory Distress Associated with Goiter

Retrosternal goitrous extension is the most common cause of respiratory distress associated with goiter. 1

Pathophysiology of Goiter-Related Respiratory Distress

Goiters can cause respiratory distress through several mechanisms:

• Retrosternal extension: When thyroid tissue extends below the thoracic inlet into the mediastinum, it can cause significant tracheal compression, especially in confined spaces of the thoracic inlet 1
• Tracheal compression: Goiters can cause mass effect on the trachea, leading to dyspnea, orthopnea, obstructive sleep apnea, and stridor 1
• Recurrent laryngeal nerve palsy: While this can cause vocal cord dysfunction and some respiratory symptoms, it is less commonly the primary cause of significant respiratory distress 1
• Malignant tracheal invasion: Though serious when it occurs, this is less common than mechanical compression from benign goiter extension 1
• Hemorrhage in large goiter: Acute bleeding into a goiter can cause rapid expansion and respiratory compromise, but this is relatively uncommon 2, 3

Clinical Presentation

Patients with respiratory distress from goiter may present with:

• Progressive dyspnea, especially when lying flat 1, 4
• Stridor and inspiratory difficulty 5
• Obstructive sleep apnea symptoms 1
• Dysphagia and dysphonia due to compression effects 1, 6
• Acute respiratory failure, particularly during upper respiratory infections 6

Diagnostic Evaluation

For suspected goiter with respiratory symptoms:

• Ultrasound: First-line imaging to confirm thyroid origin and characterize goiter morphology 1
• CT scan: Superior for evaluating substernal extension and defining the degree of tracheal compression; preferred over MRI due to less respiratory motion artifact 1
• MRI: Alternative to CT but with more respiratory motion artifact 1

Management Considerations

For goiters causing respiratory compromise:

• Surgical removal is the definitive treatment for goiters causing respiratory distress 2, 3
• In cases of acute respiratory distress, tracheal intubation may be required prior to definitive surgical management 2, 5
• The transcervical approach is usually sufficient for removal, even for goiters extending to the aortic arch 3
• Preventive removal of large or substernal goiters should be considered even before respiratory symptoms become severe 2, 6

Important Clinical Pitfalls

• Long-standing tolerance of goiter does not preclude the possibility of sudden respiratory compromise 2, 6
• Respiratory symptoms from goiter may be misdiagnosed as asthma or other pulmonary conditions 4
• Retrosternal goiters may not be apparent on physical examination, requiring imaging for diagnosis 4, 5
• Intubation can be technically challenging in patients with significant tracheal compression 5

In conclusion, while several mechanisms can cause respiratory distress in patients with goiter, retrosternal extension with resulting tracheal compression is the most common cause, requiring prompt surgical intervention to prevent respiratory failure.