Thyroidectomy: exposure and mobilisation of the gland
THE CONTEXT
Dissection during thyroidectomy requires careful exposure of the gland while protecting laryngeal nerves and parathyroid blood supply.
Strap muscles and neurovascular exposure
•
Develop the plane between the muscle layers, elevating sternohyoid laterally until the ansa cervicalis is seen, then mobilise sternothyroid from the gland while protecting its delicate vasculature.
•
The strap muscles may be divided superiorly if greater exposure is required. An artery and vein usually pass between the two strap muscles superolaterally and may be injured by excessive blunt dissection.
•
After identifying the internal jugular vein, dissect medially and deeply to identify the common carotid artery and the vagus nerve between the vessels.
•
Stimulate the vagus nerve to confirm that the nerve monitor functions. An unexpectedly short latency on the right should raise consideration of a non-recurrent right laryngeal nerve.
•
At completion of exposure, minimal blood loss should have occurred.
Upper pole mobilisation
•
Place Langenbeck retractors beneath sternohyoid, medial and lateral to the upper pole, to display the superior thyroid vascular pedicle.
•
Control the pedicle with ties or a bipolar energy device. This mobilises the superior pole, preserves the superior parathyroid blood supply and minimises risk to the superior laryngeal nerve.
•
The superior laryngeal nerve may be seen passing medially towards the cricothyroid muscle.
•
During superior pole mobilisation, avoid dissection below the cricoid cartilage because the recurrent laryngeal nerve is at risk there.
Mobilisation of the remaining gland
•
Gentle traction on the fascia over the gland reveals a plane that can be followed inferiorly. Avoid excessive lateral dissection to protect the recurrent laryngeal nerve.
•
Much of the fascia can be mobilised bluntly; occasional vessels require bipolar cautery.
•
Identify the trachea in the midline below the isthmus. Stay on the cartilage and close to the gland to protect vessels contributing to the inferior parathyroid vascular arcades.