|LETTER TO EDITOR
|Year : 2021 | Volume
| Issue : 2 | Page : 193-198
Surgical management of retrosternal (intrathoracic) goitre
KN Vijayan, Mohamad Safwan, S Akash
Department of General Surgery, Kerala Institute of Medical Sciences, Thiruvananthapuram, Kerala, India
|Date of Submission||25-Mar-2021|
|Date of Decision||05-Apr-2021|
|Date of Acceptance||07-Apr-2021|
|Date of Web Publication||15-Nov-2021|
Dr. Mohamad Safwan
Department of General Surgery, Kerala Institute of Medical Sciences, Thiruvananthapuram - 695 011, Kerala
Source of Support: None, Conflict of Interest: None
The neck is 'a space with no bottom' as described by Lahey and Swinton. Large multinodular goitre in the neck enlarges and descends to the chest for variable extent. Such goitre is called plunging or secondary retrosternal goitre. Rarely, these can be primary intrathoracic goitre from ectopic thyroid tissue. Large retrosternal goitre produces pressure symptoms and may become toxic or malignant. Thyroidectomy is the treatment of choice for retro-sternal goitre which carries great challenge for the surgeons. Here, our objectives to present (1) characteristic features of primary and secondary intrathoracic goitre. (2) Basic evaluation and concise pre-operative assessment for thyroidectomy and (3) surgical steps of the procedure emphasising on safety for a large intrathoracic goitre. Most of the cases of retrosternal goitre can be removed safely via a cervical approach.
Keywords: Intrathoracic goitre, retrosternal goitre, thyroidectomy
|How to cite this article:|
Vijayan K N, Safwan M, Akash S. Surgical management of retrosternal (intrathoracic) goitre. Kerala Surg J 2021;27:193-8
| Introduction|| |
Retrosternal goitre was first described by Albrecht Von Haller in 1749, as the extension of thyroid tissue below the upper opening of the chest. The synonyms are substernal, mediastinal complete or incomplete, intrathoracic, plunging or parasitic retrosternal goitre.
The definition of retrosternal goitre is still not uniform. The commonly accepted definition is as a goitre when more than 50% of the mass is located in the mediastinum., More precise definition include goitre lying 2 fingerbreadths below the thoracic inlet with the patient in a supine position, or goitre extension of at least 3 cm below the cervico-thoracic isthmus at computed tomography (CT) scan performed with a hyperextended neck.,
Up to 90% of retrosternal goitre is located in the anterior mediastinum, 10% in posterior mediastinum below the aortic arch and <1% seen as aberrant/ectopic mediastinal position. Retrosternal goitre can be classified as primary or secondary types.
Primary intrathoracic goitre, is very rare forming approximately <1% of mediastinal goitre. It develops from ectopic/aberrant thyroid tissue in the chest, derives blood supply exclusively from the aortic arch, innominate arteries, internal mammary or other thoracic vessels and has no connection to thyroid tissue in the neck. Cervical thyroid can be present or absent with no history of thyroidectomy. Sternotomy, thoracotomy or video-assisted thoracoscopy (VATS) may be required for safe surgery.
Secondary intrathoracic goitre, constitutes of more than 90%, up to 30% of large cervical goitre can have a retrosternal extension. It develops from a downwards extension of cervical thyroid tissue into the chest. Blood supply is from cervical thyroid mainly inferior thyroid artery. It could be a plunging or exophytic goitre with narrow thin connection with cervical thyroid lobe. Rarely, it could be a parasitic nodule developing in the chest due to attachment and migration of thyroid tissue from the lower pole following incomplete previous thyroidectomy/lobectomy. Up to 95%–98% of secondary intrathoracic goitre can be removed through the neck, except goitre extending to the posterior mediastinum, below arch of aorta, recurrent intrathoracic goitre, large exophytic goitre with the long thin narrow connection to cervical part, parasitic goitre or malignant goitre with infiltration which warrant sternotomy. Sternotomy, thoracotomy or VATS procedure may be required for removal.
| Diagnosis|| |
The diagnosis of retrosternal goitre is commonly made in the fifth or sixth decades of life with a female-to-male ratio of 4:1. Goitre remains asymptomatic for many years. About 20%–40% are discovered as an incidental finding on an X-ray chest done for cough, dyspnoea, dysphagia, dysphonia, etc. Many are referred by chest physician. Up to 30% of large cervical goitre will have the retrosternal extension. Diagnosis is made on history, clinical examination, image findings and laboratory investigations. Clinical history of neck swelling associated with symptoms of thyroid dysfunction and thoracic inlet compression may be evident in some patients. Clinical findings include neck swelling with restricted mobility inability to feel the lower limit, tracheal deviation, evidence of engorged veins of neck and chest with positive Pemberton Sign. The majority are euthyroid and some subclinical or true hyperthyroid. Cervical goitre may not be palpable is about 30% of patients.
| Investigations|| |
They include thyroid function test, serum calcium along with pre-operative evaluation, X-ray neck and thoracic inlet to assess tracheal compression by the goitre, ultrasonography of neck for the basic examination and evaluation of thyroid within the neck, CT scan of the neck and chest preferably without contrast (as the contrast may delay post-operative treatment if the goitre is malignant) to assess the extent of sub-sternal component and to delineate vascular anatomy, MRI neck complementary for exceptional precision, nuclear scan may be rarely required (as it may help to differentiate from thymoma, teratoma and lymphoma). Barium swallow may show displaced or compressed oesophagus by the goitre. Laryngoscopy was done for the assessment of vocal cord. Fine-needle aspiration biopsy is always not mandatory as it may produce acute dyspnoea. Pulmonary function test is to assess lung status in large retrosternal goitre and to document the presence of underlying lung pathology. Cardiac assessment is also mandatory for symptomatic patients.
| Treatment|| |
Surgery is the treatment of choice. Asymptomatic patient may develop life-threatening emergency complications. Treatment with thyroid suppression or anti-thyroid drugs is not effective.
Informed consent explaining the procedure, the possibility of difficult intubation, delayed extubation, sternotomy, tracheostomy, blood transfusion, post-operative hypocalcaemia, voice change, etc., shall be taken. Pre-operative nebulisation and a short course of steroid therapy may be helpful in some cases.
Marking of a low collar incision in a sitting position in ladies may be useful to avoid a low-level scar over the sternum. Position-supine position with both arms tucked by the patient's side and with a folded blanket or sandbag keeping behind the scapula to allow a passive cervical extension. Anaesthesia-Endotracheal Anaesthesia General with or without using video laryngoscopy and the tube is secured away from the surgical field. Drape the neck and chest anticipating sternotomy, infiltration of local anaesthetic along with the collar or kocher' incision site [Figure 1]. [Figure 2] shows extensive mobilisation of the subplatysmal flap with suture retraction. [Figure 3] shows bilateral lateral mobilisation of sternocleidomastoid muscles from strap muscles . [Figure 4] shows vertical incision of midline cervical fascia [Figure 4]. Mobilise sternohyoid muscles laterally [Figure 5]. Ligate and divide anterior jugular veins, and suture retracts the sternohyoid muscles [Figure 6] and [Figure 7]. Sternothyroid is also gently separated from thyroid and divide upper attachment and keep retracted [Figure 8]. Palpate and identify if possible the infra-isthmic part of displaced/compressed trachea. Prominent inferior thyroid veins may be ligated and divided as close to the infra-isthmic portion as possible, taking care of inferior parathyroids and possibly deviated recurrent laryngeal nerve (RLN). The superior pole of the less involved side is mobilised first. Harmonic device or good bipolar diathermy will be useful. Pull the superior pole medially and anteriorly with a Babcock forceps and divide the vessels on the exposed lateral aspect of the less vascular area. Retract the superior pole laterally and downwards to open the space between the lobe and thyroid cartilage (reeds space) to avoid injury to the external laryngeal nerve and cricothyroid muscle. Divide the superior thyroid vessel individually as close to the thyroid as possible. The upwards extension of the superior pole can be mobilised similarly by re-application and traction of the lobe as before. Try to identify and preserve the superior parathyroid. The less involved nonetrosternal side need not be removed at this stage if there is apprehension for the safety of para-thyroids and RLN of the large retrosternal goitre lobe. Divide the isthmus so that the blood from this side to the large retrosternal side becomes cut-off. It also helps in mobilising the isthmic attachment between the trachea and the retrosternal goitre side. This may help in mobilisation and delivery of the retrosternal side later. Divide and ligate the compressed capsular vessels over the infra isthmic part of retrosternal goitre taking care of a possible deviated RLN on that side. Ligate and divide middle thyroid veins on either side. Vertically expose the space between the carotid artery and thyroid on each side from hyoid to sternum [Figure 9]. Compressed goitre will become prominent and become well exposed. Mobilise the pyramidal lobe downwards up to the isthmus. Mobilise the superior pole of the retrosternal goitre lobe. Try to identify and preserve the superior parathyroid. Dissect and widely open the space between the thyroid and common carotids. Divide and ligate the middle thyroid veins if not already done. Divide and ligate the capsular vessels over the retrosternal lobe in a lateral to the medial direction just above the sternal level. Keeping dissection as close to the capsule as possible in a bloodless field the cervical part of the RG can be mobilised medially to see the inferior thyroid artery coming under the carotid and the RLN on the posteromedial aspect within the trachea-oesophagal groove or mass medially. In case of recurrent goitre or enlarged Riedel's lobe, the RLN may be found in an anterior position. The inferior parathyroid identification may be difficult. Dissection of superior thyroid artery, carotids, internal jugular vein and recurrent laryngeal nerve are depicted in [Figure 10], [Figure 11], [Figure 12]. The RLN found can be fully tracked and the remaining part of Berry's ligament divided to free the side from the tracheal attachment [Figure 13]. By all these measures the most of the vascular connection from the neck except the branch from inferior thyroid is divided. Gentle traction by holding with gauze or with a large silk suture and by rocking movements and blunt finger dissection retrosternal goitre can be mobilised slowly upwards. The remaining lower polar vessels are ligated or sealed with Harmonic device as the specimen can be removed. Sternotomy may be needed if there is difficulty in removing the retrosternal goitre due to very large size or infiltration to anterior mediastinal structures or for uncontrollable bleeding. Inter-costal Drainage may be indicated for pneumothorax or haemothorax. If the safety of RLN and parathyroid is assured, the other lobe when found abnormal can also be removed. Devascularised parathyroid should be transplanted in the ipsilateral sternocleidomastoid muscles. Use of nerve stimulator devices is complimentary. The visual method still remains the gold standard. After successful cervical thyroidectomy, if the strap muscles were divided and if sternocleidomastoid muscles are retracted, it can be sutured back with 3-o vicryl sutures. The strap muscles are sutured in the midline with interrupted using 3-o vicryl after keeping a suction drain [Figure 14]. The platysma is closed with interrupted 3 o vicryl and skin closed with sub-cuticular absorbable suture. [Figure 15] shows the excised specimen. For patients with evidence of tracheomalacia try for delayed extubation after 24–48 h in the theatre. If dyspnoea persists exclude bilateral RLN injury by vocal cord examination and patient needs tracheostomy. Post-operative management should be in the intensive care unit.
|Figure 6: Ligation and division of anterior jugular veins and sternohyoid muscles|
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|Figure 8: Suture enlarged thyroid gland with retrosternal extension with retracted strap muscles|
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|Figure 11: Exposing internal jugular vein and carotid artery after mobilisation of the retrosternal portion of the thyroid|
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|Figure 14: Strap muscles and sternocleidomastoid muscles are sutured back with interrupted using 3-o vicryl after keeping a suction drain|
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Complications include post-operative haemorrhage or haematoma, pneumothorax, haemothorax or rarely chylothorax, hypocalcaemia, either temporary or permanent, RLN palsy either temporary or permanent and injury to the phrenic nerve, cervical sympathetic chain.
| Conclusion|| |
Surgical removal of retrosternal goitre is a challenging procedure which can be safely performed in most cases by cervical approach. Complications are slightly higher than that for a cervical goitre. Thyroidectomy for intra-thoracic primary goitre, retrosternal extending to posterior mediastinum, below aortic arch, infiltrating malignant or recurrent or large parasitic goitre sternotomy, thoracotomy or VATS may be required in such cases.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15]