Thyroidectomy: It’s Not All About the Nerve
Total thyroidectomy is a common procedure that can be associated with several complications. Most are mild, but some can be devastating to quality of life. If you think nerve injury is the most common complication, you are wrong. The most frequent complication following total thyroidectomy is hypoparathyroidism (hypoPT).
The 2018 American Thyroid Association (ATA) Statement on Postoperative Hypoparathyroidism is a very interesting and valuable document. Although it does not address the use of NIRAF or ICG, many of the concepts discussed remain important and highly relevant to all surgeons performing thyroid surgery. The reported rates of transient and permanent hypoparathyroidism are as high as 38% and 3%, respectively. Fortunately, severe symptomatic cases are rare; however, when they occur, they can have a major impact on patients’ quality of life. Therefore, all surgeons performing thyroid surgery should be aware of the potential impact of this complication.
What can the patient feel?
Paresthesias in the hands and around the mouth are usually the earliest symptoms.
Muscle cramps and spasms, which may progress to laryngospasm.
Neuropsychiatric symptoms, including confusion, aggression, depression, and irritability.
Seizures in severe cases.
What can we see in the patient?
Chvostek’s sign: facial muscle contraction elicited by tapping over the facial nerve in the preauricular region.
Trousseau’s sign: flexion of the wrist, thumb, and metacarpophalangeal joints, with extension of the other fingers, induced by occlusion of the brachial artery with a cuff inflated above systolic blood pressure.
QT interval prolongation, which may predispose to ventricular arrhythmias, including ventricular fibrillation.
All these symptoms and signs can render patients unable to perform their daily activities. That is why the surgeon must make every effort to ensure that the parathyroid glands are left in situ, with an adequate blood supply and venous drainage. Why? Because the mechanisms underlying postoperative hypoparathyroidism include mechanical or thermal trauma, inadvertent removal, injury to the arterial blood supply, and impairment of venous drainage. In fact, vascular injury is relatively easy to cause because the parathyroid blood supply, which usually arises from branches of the inferior thyroid artery, is very fragile.
Are there risk factors for hypoparathyroidism? Of course there are.
Bilateral thyroidectomy (simultaneous or staged)
Autoimmune thyroid disease (Graves’ disease, lymphocytic thyroiditis)
Central compartment dissection (prophylactic or therapeutic)
Previous gastric bypass or other malabsorptive procedures (increased risk of calcium and vitamin D deficiency, and greater vulnerability to postoperative hypocalcemia)
Simultaneous thyroidectomy and parathyroidectomy
Previous neck surgery (reoperations)
Inexperienced surgeon
The best way to avoid postoperative hypoparathyroidism is to reduce the extent of thyroid surgery (whenever appropriate), favouring a unilateral procedure. In this way, the contralateral parathyroid glands can be protected, ensuring that at least one parathyroid is functioning at the end of the procedure.
Good surgical technique is of paramount importance. A surgeon should be able to identify the parathyroid glands, bearing in mind that they are very small, have a colour similar to that of the surrounding structures, and have a highly variable anatomical location. Dissection should remain close to the thyroid capsule, medial to the parathyroid glands, gently pushing the perithyroidal tissue away (hopefully with the parathyroid glands within). I usually use blunt dissection with a peanut dissector—it works very well. This allows vascular ligation to be performed distal to the branches supplying the parathyroid glands.
Remember: the aim is not simply to leave the parathyroid glands in situ. The aim is to leave them in situ and functioning.
The use of surgical loupes has been associated with a reduction in the rate of inadvertent parathyroid removal, from 7.8% to 3.8%, as well as a reduction in clinical hypocalcemia, from 33% to 12.7%. Energy devices can cause thermal injury; however, their use also has advantages, particularly in reducing bleeding complications. Keeping the energy device 3–5 mm away from the parathyroid gland can help reduce the risk of thermal injury.
Surgeons must keep one principle in mind: in thyroid surgery, we do not search for the parathyroids; we find them. Several studies have reported that actively searching for and identifying three or four parathyroid glands may increase the rate of postoperative clinical hypocalcemia. Additionally, the inferior parathyroid glands are more frequently preserved, possibly because their embryological development with the thymus means that they may be located farther from the thyroid gland.
A final word about parathyroid autotransplantation. Some authors have advocated its use as a means of preventing postoperative hypoPT. However, several studies have shown that autotransplantation increases the rate of transient hypoparathyroidism, without reducing the incidence of permanent hypoparathyroidism. Therefore, autotransplantation should only be performed when the gland is clearly devascularized at the end of surgery. How can you determine this? By assessing the color of the gland and/or by using ICG angiography. But that is another story…
Do you want to know more about ICG and NIRAF? Click here.
In the end, hypoparathyroidism can be a devastating and difficult-to-treat complication. Surgeons should use a meticulous thyroidectomy technique to preserve the parathyroid glands in situ and maintain their normal function. Whenever appropriate, reducing the extent of thyroidectomy from bilateral to unilateral surgery is the most effective way to avoid this complication.
Many patients have the misconception that thyroid surgery is a simple procedure, coming to the consultation primarily concerned about nerve preservation, and often requesting a total rather than a partial thyroidectomy. Educating patients that nerve injury is not the most common complication, that hypoparathyroidism can have a significant negative impact on quality of life, and that, whenever appropriate, reducing the extent of thyroidectomy is the most effective way to minimize the risk of hypoparathyroidism is the responsibility of all physicians.
Patients must be fully aware of the risks associated with their decision and accept those risks before undergoing surgery.
Link to ATA Statement:
Dr. Carlos Eduardo Costa Almeida
General Surgeon
Comentários