A rare instance of retrosternal goitre presenting with obstructive sleep apnoea in a middle-aged person

Abstract

INTRODUCTION

In endemic goitre areas, 20% of the population over 70 will have retrosternal goitre.¹² Obstructive sleep apnoea (OSA) occurs when there are repeated episodes of complete or partial blockage of the upper airway during sleep.

PRESENTATION OF CASE

A 55-year-old man was being treated for obstructive sleep apnoea, came with stridor worsening over the 2 and was advised CPAP ventilation. In our institution, he was diagnosed to have goitre with retrosternal extension with no hypo/hyperthyroidism. He was an obese (BMI – 30 Kg/m²) male with a short, broad neck and clinically no obvious swelling in the neck. He had stridor, with positive Kocher's test as well as Pemberton's sign. His TFT's were normal and CT scan revealed widening of superior mediastinum. Patient was pre-medicated with low dose (0.1 μg) fentanyl, and induced with inhalational anaesthesia (sevoflourane). Endotracheal intubation was done using 6 no. ET tube, without muscle relaxation, and the thyroid was removed through a conventional Kocher's incision. Thyroid was enlarged 25 cm by 10 cm in retrosternal position. Postoperatively, pt was reversed and shifted to ICU, was monitored for the next 24 hours. He was extubated uneventfully the next morning. Patient had a good post-op recovery and was discharged on the 7th post-op day.

DISCUSSION

Terms such as retrosternal, substernal, intrathoracic, or mediastinal have been used to describe a goitre that extends beyond the thoracic inlet. However, there is a lack of consensus regarding the exact definition of a retrosternal goitre (RSG).¹ The majority of patients present with shortness of breath or asthma like symptoms (68.8%), as was the case in the studied patient. Other modes of presentation include neck mass (75%), hoarseness of voice (37.5%), dysphagia (31.3%), stridor/wheezing (19%), or SVC obstruction. Upper airway obstruction due to thyroid gland has been reported up to 31%² and difficulty in intubation has been reported in 11%.³ Central airway obstruction produces symptoms of dyspnoea, stridor, or obstructive pneumonia and is often misdiagnosed as asthma.⁴ The CT scan was the most useful tool showing the nature and extent of the lesion in the reported case. In a recent publication, the CT scan was considered the gold-standard preoperative radiological investigation.⁵ Surgery is the only effective treatment for retrosternal goitres. In most cases, suppressive therapy with thyroxine is ineffective in reducing the size of multinodular goitres;^7,8 radio-iodine therapy is both generally ineffective in large goitres⁸ and may induce acute inflammation and swelling of the gland with the potential for airway obstruction. The operation of choice is usually a total thyroidectomy. Only around 2% of patients undergoing thyroidectomy for retrosternal goitre will require surgical access other than a standard collar incision (either manubriotomy, sternotomy or thoracotomy).⁹

CONCLUSION

Despite all the advances in investigative modalities, retrosternal goitre still exists in 20% of patients over 70 years in endemic regions. It has to be recognised that it can be a cause of obstructive sleep apnoea. Early detection and prompt management goes a long way in decreasing the morbidity and mortality in patients with RSG.

1. Introduction

As described by Candela in 2007, any goitre that descends below the plane of the thoracic inlet or grows into the anterior mediastinum for more than 2 cm is considered retrosternal. In endemic goitre areas, 20% of the population over 70 will have retrosternal goitre.¹² Obstructive sleep apnoea (OSA) occurs when there are repeated episodes of complete or partial blockage of the upper airway during sleep. In this article, we present a patient with OSA who was subsequently found to have a retrosternal goitre.

2. Case report

A 55-year-old diabetic and hypertensive man, being treated for obstructive sleep apnoea, presented with stridor worsening over the previous two years interfering in his daily life. His sleep was disturbed due to sudden apnoea and a choking sensation at night, stridor at rest and hoarseness. He was being treated with CPAP ventilation.

He was an elderly male, obese (BMI – 30 kg/m²) with a short, broad neck and clinically no obvious swelling in the neck. He had stridor, with Kocher's test and Pemberton's sign positive. His thyroid function tests were within normal limits. His chest X-ray showed widening of superior mediastinum.

On CT, there was a large exophytic well-defined heterogeneously enhancing nodule arising from the lower pole of the right lobe of the thyroid gland with retrosternal extension measuring 5.83 cm × 5.22 cm in max dimensions and 7.55 cm in supero-inferior extent, with a dystrophic calcific focus in its lower portion, causing severe lateral compression of trachea with minimum diameter of 0.38 cm at the site of compression with deviation towards the left. Indirect laryngoscope examination was not possible as patient was severely breathless on attempting the same (Figs. 1–4).

Fig. 1.

Patient in pre-operative state.

Fig. 2.

CT scan images – showing the retrosternal extent of the goitre.

Fig. 3.

Gross specimen of thyroid.

Fig. 4.

Microscopic view of the colloid adenomatous goitre.

The patient was pre-medicated with low dose (0.1 μg) fentanyl, and induced with inhalational anaesthesia (sevoflourane). Endotracheal intubation was achieved with a number 6 endotracheal tube, without muscle relaxation, which would have comprised the airway resulting in disastrous consequences and was mechanically ventilated. The thyroid was removed through a conventional Kocher's incision.

At surgery, the right lobe of thyroid was enlarged and nodular measuring 15 cm × 10 cm with 10 cm × 10 cm retrosternal extension. The left lobe measured 15 cm × 8 cm, and was nodular. Right upper and left lower parathyroids and on the right side the recurrent laryngeal nerve was elongated and pushed downwards by the retrosternal extension and was identified and preserved.

The patient was extubated uneventfully the next morning. He made a good post-operative recovery and was discharged on the seventh day. Histological examination confirmed colloid adenomatous goitre. After a month the patient complained of insomnia but had no symptoms of obstructive sleep apnea. He could now lie down in supine position without any complaints. He required about two months of Miloset (3 mg HS) for his sleep rhythm to return to normal.

3. Discussion

Terms such as retrosternal, substernal, intrathoracic, or mediastinal have been used to describe a goitre that extends beyond the thoracic inlet. However, there is a lack of consensus regarding the exact definition of a retrosternal goitre (RSG).¹ The significant variability found in the literature regarding the clinical presentation and the surgical management of RSG can at least in some part, be explained by the different definitions employed.

The natural history of retrosternal goitre is of a slow relentless increase in size, often presenting as an incidental finding on a chest X-ray in the fifth or sixth decade of life. The most common symptom is a feeling of pressure, due to the compression of the airway or great veins in the neck.⁶

The majority of patients present with shortness of breath or asthma like symptoms (68.8%) as was the case in the studied patient. Other modes of presentation include neck mass (75%), hoarseness of voice (37.5%), dysphagia (31.3%), stridor/wheezing (19%), or SVC obstruction. Upper airway obstruction due to thyroid gland has been reported up to 31%² and difficulty in intubation has been reported in 11%.³ Central airway obstruction produces symptoms of dyspnoea, stridor, or obstructive pneumonia and is often misdiagnosed as asthma.⁴

Thyrotoxic features are reported in less than 10% of RSG cases.² The CT scan was the most useful tool showing the nature and extent of the lesion in the reported case. In a recent publication, the CT scan was considered the gold-standard preoperative radiological investigation.⁵

Prospective studies document the incidence of carcinoma development in goitres at 1.3–3.7 new cases per 1000 patients.^10,11 A recent review of evidence-based management of sub-sternal goitres concluded that the incidence of malignant transformation is equivalent in retrosternal goitres to those residing entirely in the neck.⁹

Surgery is the only effective treatment for retrosternal goitres. In most cases, suppressive therapy with thyroxine is ineffective in reducing the size of multinodular goitres^7,8; radio-iodine therapy is both generally ineffective in large goitres⁸ and may induce acute inflammation and swelling of the gland with the potential for airway obstruction.

The operation of choice is usually a total thyroidectomy, eliminating the need for potential secondary surgery due to regrowth of retained thyroid tissue. That said, on many occasions the retrosternal growth is often confined to just one side of the thyroid allowing the possibility of more limited surgery.¹ Only around 2% of patients undergoing thyroidectomy for retrosternal goitre will require surgical access other than a standard collar incision (either manubriotomy, sternotomy or thoracotomy).⁹ The thyroid is usually removed through a conventional thyroid incision in the neck, but occasionally division of the upper part of the breast bone (sternum) is necessary, a procedure called a manubriotomy.⁵ For access in which the cervical approach is not adequate, an intrathoracic approach should be employed including manubriotomy, full sternotomy and lateral thoracotomy.⁹

4. Conclusion

The possibility of a retrosternal goitre should be borne in mind when evaluating patients with breathing difficulties in goitre-endemic areas.

Conflict of interest statement

None.

Funding

None.

Ethical approval

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Author contribution

The study was conceptualized by Dr. Jude Rodrigues and designed by Dr. Renny Furtado. Quality control of data and algorithm and manuscript review were also done by Dr. Jude Rodrigues. The data were acquired by Dr. Sanyam Falari. Data were analysed and interpreted by Dr. Nivedita Mitta. Dr. Nivedita Mitta also prepared the manuscript. Statistical analysis was done by Dr. Shantata Kudchadkar. The manuscript was edited by Dr. Renny Furtado.