First tracheal ring fracture in a complex thyroid surgery

Highlights • Graves’ disease treated by one of three approach which are pharmacological, 131I-radiotherapy, or thyroidectomy.• Methimazole and Carbimazole are considered the first line of treatment for Graves’ disease.• Most of thyroidectomy complications are rare and transient.• Tracheal injury accounts for less than 1 % of all thyroidectomy complications.


Introduction
Thyroidectomy is one of the common and safe procedures done by the endocrine surgeons to treat both benign and malignant thyroid diseases, with very low complications rate. However, there are some rare complications that might suddenly appear during thyroidectomy, tracheal injury is one of them. Tracheal injury accounts for less than 1 % of all thyroidectomy complications. It is usually recognized and repaired intraoperatively, however late recognition can lead to serious and life-threatening complications such as tracheal necrosis and contamination [1,2]. This work has been reported in line with the SCARE criteria [3].

Case report
A 48-year-old gentleman, was medically free, presented to the endocrine clinic with history of palpitation, heat intolerance, fine tremor and unintentional weight loss. On September 2018, the patient was diagnosed with Graves' disease and was started on Propylthiouracil (PTU) and Propranolol since that time. The patient was not responding to medical treatment and was referred to our endocrine surgery clinic for total thyroidectomy.
During the total thyroidectomy, the surgery was complicated by first tracheal ring fracture. A small tracheal laceration that happened on the right side between the cricoid cartilage and first tracheal ring during shaving the thyroid from the trachea. Interestingly, the tracheal injury was repaired with 3 Prolene stiches.

Discussion
Graves' disease is an autoimmune disease that affect thyroid gland mainly. It results from overproduction of thyroid hormone which caused by stimulation of the thyroid gland through binding of pathogenic antibodies thyroid receptor antibodies (TRAb) which also called thyroid stimulating immunoglobulin (TSI) that synthesized by the B lymphocyte to the thyroid stimulating hormone (TSH) receptors. It is characterized by hyperthyroidism, goiter due to the effect of TSI on the thyroid gland, and in some patients, graves' ophthalmopathy that might include exophthalmos, chemosis, lid-lag and lid-retraction as a result of the inflammation, and proliferation of the extraocular muscles and retro-orbital connective and adipose tissues secondary to the effect of TSI and cytotoxic  T lymphocyte. It is the most common cause of hyperthyroidism in the iodine sufficient areas, account for 60-80 % of all cases. Many studies found that the incidence is around 24.8 patients per 100,000 per year. Graves' disease is more common in female, suggested by some data that reports approximately 2 % of female and 0.2 % of male develops graves' disease during their life. [4][5][6][7][8]

Management
Hyperthyroid due to Graves' disease treated by one of three approach which are pharmacological, 131 I-radiotherapy, or thyroidectomy. The choice of appropriate approach depends on many factors, but the main goals of treatment are to restore thyroid function, prevent recurrence and hypothyroidism. The first approach is antithyroid drugs: propylthiouracil (PTU), and thionamide derived antithyroid drugs include methimazole and carbimazole are considered the first line of treatment for Graves' disease. These drugs decrease level of thyroid hormones (T 3 and T 4 ) by inhibiting Thyroid peroxidase (TPO) action which play a role in the synthesis of thyroid hormones. In addition to that, PTU prevent the peripheral conversion of T 4 to T 3. American Thyroid Association (ATA) and American Association of Clinical Endocrinologists (AACE) guidelines suggested that all the patient who are candidate for antithyroid drugs should be treated with methimazole except women in the first trimester of pregnancy, during thyroid storm, and patients who develop adverse events secondary to methimazole. The main adverse events of antithyroid drugs are hepatitis, jaundice, urticaria, rash, lupus like syndrome, and agranulocytosis [9][10][11].
The second approach to treat patients with Graves' disease is 131 I-radiotherapy which acts by destruction of thyroid tissue leading to hypothyroidism in most of the patients. It is indicated in the patients who are not candidate for antithyroid drugs, or who want definitive treatment without the risk of surgery. However, it is contraindicated in pregnancy and breast feeding [9,10].
The third modality to treat the patients with Graves' disease is thyroidectomy which is the definitive treatment for these patients. But it is the least chosen modality due to the risk of complications although the rate of recurrence of Graves' after surgery is 0 %. The complication rate after surgery is more drastic than the other modality, however, the complications are rare and transient in most of the cases. The complications might include hypocalcemia, recurrent laryngeal nerve injury, hypoparathyroidism, hematoma, and wound infection. It is indicated when there is failure in medical treatment, refusal or low uptake of 131 I, large goiter that cause compressive symptoms, malignancy suspicion, Graves' ophthalmology, and pregnancy planning in the near future. Regarding the extant of thyroidectomy, total thyroidectomy is better than sub-total, although many recent studies reported that there is no difference in the complications rate expect the rate of recurrence is higher in sub-total thyroidectomy [5,7,9,10,12].
Preparations should be considered before surgery to decrease the risk of developing some complications that include euthyroid state before surgery to decrease risk for thyroid storm. This could be achieved by using antithyroid medication 1-3 months before surgery, however, there are some patient required urgent surgery, in these cases, ␤-blocking drugs, potassium iodine, dexamethasone, and cholestyramine are recommended. Administration of potassium iodine for 10-14 days also can be used to decrease thyroid vascularity that minimize intraoperative blood loss [13,14].
One of the rare complications of thyroidectomy is tracheal injury. It accounts for less than 1 % of all thyroid complications. There are many preoperative, intraoperative, and postoperative risk factors that can lead to tracheal injury that includes goiter. Many studies reported that continuous compression on the trachea by large goiter can lead to tracheal weakness and tracheomalacia which is define as weakness of the tracheal cartilages and hypotonia of the elastic elements. Female gender is considered another risk factor for tracheal injury. Regarding intraoperative causes include prolong intubation, high cuff pressure that lead to vasoconstriction, decrease blood supply to trachea, and subsequently tracheal damage, inability to recognize thyroid plane of dissection in the case of multi-nodular goiter, and lastly uncontrolled postoperative cough [2,15,16].
Diagnosis of the tracheal injury can be intraoperative or postoperative, the common signs of tracheal injury are Pneumo- Fig. 2. management of tracheal injury [18]. mediastinum and subcutaneous emphysema. Tracheal injury can managed conservatively or surgically depend on the size of the injury, in some cases delay discovery of the injury can lead to tracheal necrosis which should be managed by debridement to revitalize the trachea. Small injury without air leakage in the mediastinum managed conservatively by bed rest, antibiotics, and cough suppression followed by primary closure of the wound by suture if the conservative management failed. In contrast large wound or contaminated wound managed by different methods but the most effective method is closure with suture with or without muscle flap, (Fig. 2) [17][18][19].

Conclusion
Tracheal injury is a rare but life-threatening complication of thyroidectomy, that can be managed easily if discovered early. Indications of thyroidectomy should be studied very well before making any decision, although putting those rare complications in our consideration is another matter. Awareness about these rare complications, and their risk factors can help in preventing them and decreasing their mortality and morbidity.

Declaration of Competing Interest
No conflict of interest to declare Sources of funding no source of funding

Ethical approval
Institutional Review Board approval. Case Report is presented anonymously.

Consent
Informed written consent was taken from patient

Author contribution
Raja Husain: writing the paper, submission Asayil Alnasser: writing the paper Mohammed Al Duhileb: writing and revision of the paper Tariq Madkhali: revision of the paper

Registration of research studies
Not Applicable (Case Report; not an interventional study).

Guarantor
Mohammed Al Duhileb Department of Surgery, king Fahad specialist hospital, Dammam, Saudi Arabia.