Retrosternal Goitre
On this page
Direct answer
When more than half of a goitre's mass lies below the thoracic inlet — the commonly quoted definition — it is a retrosternal (substernal) goitre, found in roughly 2-10% of goitres. Most descend from the neck into the anterosuperior mediastinum along the plane of least resistance, remaining connected by a pedicle and fed by the inferior thyroid artery; a true ectopic mediastinal thyroid with its own aortic blood supply is rare. Presentation ranges from an incidental chest X-ray mass to positional dyspnoea, stridor, dysphagia, hoarseness and superior vena cava obstruction (Pemberton's sign on raising the arms). Because the gland cannot be examined bimanually and the airway is at stake, contrast-enhanced CT of neck and chest is the investigation of choice, and surgical removal — almost always achievable through the cervical route in over 90% — is the treatment, since these goitres progressively compress rather than regress.
What you must remember
- Definition: more than 50% of the gland below the thoracic inlet; incidence commonly quoted at 2-10% of thyroidectomies.
- Mediastinal compartments: anterior-superior descent is usual (the gland follows the inferior thyroid artery plane); posterior descent into the posterior mediastinum is rarer and flips the recurrent laryngeal nerve relationship — the nerve then lies anterior to the gland, a trap during dissection.
- Pemberton's sign: facial plethora, distension of neck veins and respiratory distress when the arms are raised — the goitre occludes the thoracic inlet; it is the bedside signature of venous compression.
- Symptom set: dyspnoea worse on lying flat or raising arms, stridor, dysphagia, hoarseness, and SVC obstruction; many are asymptomatic and found incidentally.
- Investigation of choice: contrast-enhanced CT of neck and thorax delineating tracheal deviation, compression and the lower extent; ultrasound cannot see below the inlet, and isotope scanning has little role.
- Physiology tie-in: flow-volume loop shows flattening of both inspiratory and expiratory limbs — variable extrathoracic upper-airway obstruction — a favourite integrated question.
- Airway anaesthesia: fibreoptic or gas induction techniques are used; long-acting muscle relaxants are avoided until the airway is intubated and confirmed, because the compressed trachea may not be ventilatable once spontaneous effort is lost.
- Post-operative vigilance: tracheomalacia can cause collapse after extubation in long-standing compression — a low threshold for reintubation; also haematoma, recurrent laryngeal nerve and parathyroid risks of total thyroidectomy.
A typical exam case
A 62-year-old man reports breathlessness when lying flat for three months and a choking sensation when he raises his arms overhead. Examination shows a lower-neck fullness you can feel above the manubrium but not below, tracheal deviation to the right, and dilated chest-wall veins. The sequence the examiner wants: chest X-ray (mediastinal mass, tracheal deviation), contrast CT neck-thorax confirming a heterogeneous goitre with over 50% below the inlet and tracheal narrowing, vocal cord check by indirect laryngoscopy before any surgery (a pre-operative cord palsy changes consent and approach), then total or near-total thyroidectomy. The cervical approach with careful delivery of the gland delivers over 90% of retrosternal goitres; median sternotomy is reserved for the truly ectopic, the hugely descending inferior extension, or invasive disease. The unwritten fourth step is the post-extubation plan: keep the patient monitored overnight for tracheomalacia and haematoma, with reintubation equipment at the bed.
Where students slip
Two answers cost marks repeatedly. The first is imaging: "ultrasound neck" for a retrosternal goitre is wrong because the sternum is acoustic barrier — CT with contrast is the answer. The second is the approach: candidates jump to sternotomy, whereas the examinable truth is that the vast majority are removed through the neck because they retain their cervical pedicle; sternotomy belongs to ectopic mediastinal thyroid or invasive disease. Third, the Pemberton's sign question — ask what raising the arms does, and answer venous obstruction, not simply "airway compression". Finally, the flow-volume loop: flattened inspiratory and expiratory limbs localise the lesion to a fixed or variable extrathoracic obstruction — quoting the loop earns the integrated mark in physiology-cum-surgery stems.
Frequently asked questions
What defines a retrosternal goitre?
More than 50% of the thyroid mass lying below the thoracic inlet. Most remain connected to the cervical gland by a pedicle and share its inferior thyroid blood supply.
Which investigation is preferred?
Contrast-enhanced CT of the neck and chest, which maps tracheal compression, deviation and the inferior extent. Ultrasound is blind behind the sternum.
What is Pemberton's sign?
Facial plethora and respiratory distress on raising both arms, from thoracic inlet obstruction of venous return. It signals a goitre that will compress further with posture.
Which surgical approach is used for most retrosternal goitres?
The cervical approach succeeds in over 90% because the gland retains its neck attachment. Median sternotomy is needed only for ectopic, very large or invasive mediastinal glands.
Why delay muscle relaxation at induction?
With critical tracheal compression, spontaneous ventilation may be the only oxygenation until the airway is secured with a fibreoptic technique. Paralysing first risks a cannot-ventilate catastrophe.