Thyroid Disease And Surgery

Surgery has a significant role in the management of thyroid disease in patients with simple goitre, thyroid nodules, thyrotoxicosis, thyroid cancer and exophthalmos.

Most euthyroid multinodular goitres do not necessarily require surgery or medical therapy. Serial thyroid ultrasound is useful to follow the size of individual nodules. Larger multinodular goitres require either CT or MRI scan in order to exclude tracheal compression and to assess thyroid size. The definitive treatment for toxic multinodular goitres is biopsy of suspicious nodules or surgical excision, followed by radio-iodine therapy. Surgery is indicated in simple goitre if:

• There is clinical or radiological evidence of compression
• Substernal goitres: are best removed surgically, as biopsy is difficult and clinical observation without frequent CT or MRI scans is impossible
• The goitre continues to grow
• Cosmetic reasons if large or unsightly.

Near total thyroidectomy is now the most common procedure. This reduces the risk of recurrence but makes hypothyroidism almost inevitable. Indications for thyroidectomy in hyperthyroidism are¹:

• Patient preference, e.g. fear of radio-iodine
• Children (radio-iodine or prolonged drug treatment remain an option)
• Pregnancy (medical treatment is usually preferred)
• Large goitre (particularly multinodular goiter, with local compressive symptoms)
• Severe reaction to anti-thyroid drugs (but radio-iodine remains an option)
• Severe ophthalmopathy (medical therapy remains an option)
• Suspicious nodule plus hyperthyroidism (perform fine needle aspiration cytology first)
• Complex situations, e.g. poor compliance with anti-thyroid drugs and radio-iodine is refused.

Indications for surgery on thyroid nodules:

• Malignant or suspicious fine needle aspiration cytology
• Larger nodule with repeated non-diagnostic fine needle aspiration
• Continued growth of nodule after fluid removal and thyroid hormone therapy
• Symptomatic nodules (pain or pressure)
• Continued patient anxiety
• Some clinicians recommend surgical removal of all nodules of diameter over 4 cm
• Hot nodules: a hyperthyroid hot nodule should be treated with radio-iodine or surgery. Surgical thyroid lobectomy is effective and safe therapy for hot nodules, and the risk of hypothyroidism after a hemithyroidectomy is low.

Well-differentiated thyroid cancer

Bilateral total or near-total thyroidectomy with appropriate nodal dissection is the procedure of choice for all but the smallest papillary carcinomas.²

Medullary thyroid carcinoma

• Treatment is surgical, consisting of bilateral, near- total thyroidectomy, central lymph node compartment dissection, and exploration of the jugular lymph node chain³
• Pre-operative screening for phaeochromocytoma is mandatory prior to surgery for medullary thyroid carcinoma, because hypertensive crisis may develop if surgery is performed on a patient with an unsuspected phaeochromocytoma (associated with medullary thyroid carcinoma in MEN Type II).

Anaplastic thyroid carcinoma

• Commonly presents as a rapidly-growing mass, often with symptoms of compression of neck structures and early development of distant metastases
• When complete resection is possible, surgical resection followed by external radiation may be beneficial
• More often, resection is not possible but external radiation may control aggressive local neck disease.

• Thyrotoxic patients should have treatment with propranolol and/or carbimazole to ensure they are euthyroid at operation
• Potassium iodide has also been used
• In view of the possible operative damage to the recurrent laryngeal nerve, the vocal cords should also be checked prior to thyroid surgery.

Possible complications following thyroid surgery are⁴:

• Bleeding: may cause tracheal compression
• Recurrent laryngeal nerve injury:
  • Innervates all of the intrinsic muscles of the larynx, except the cricothyroid muscle
  • Patients with unilateral vocal fold paralysis present with postoperative hoarseness
  • Presentation is often subacute and voice changes may not present for days or weeks
  • Unilateral paralysis may resolve spontaneously
  • Bilateral vocal fold paralysis may occur following a total thyroidectomy, and usually presents immediately after extubation
  • Both vocal folds remain in the paramedian position, causing partial airway obstruction.
• Hypoparathyroidism: the resulting hypocalcaemia may be permanent but is usually transient. The cause of transient hypocalcaemia postoperatively is not clearly understood.
• Thyrotoxic storm: is an unusual complication of surgery but is potentially lethal
• Superior laryngeal nerve injury:
  • The external branch provides motor function to the cricothyroid muscle
  • Trauma to the nerve results in an inability to lengthen a vocal fold and thus to create a higher-pitched sound
  • The external branch is probably the most commonly injured nerve in thyroid surgery
  • Most patients do not notice any change but the problem may be career-ending for a professional singer.
• Infection: occurs in 1-2% of all cases. Peri-operative antibiotics are not recommended for thyroid surgery.
• Hypothyroidism.

In one recent large study, the rate of complications following thyroid surgery were as follows⁵:

• Persistent hypoparathyroidism in 1.7%, and temporary hypoparathyroidism in 8.3%
• Permanent recurrent laryngeal nerve palsy in 1.0% of patients and transient palsy in 2.0%
• The superior laryngeal nerve was damaged in 3.7%.