Improving Voice Outcomes After Thyroid Surgery – Review of Safety Parameters for Using Energy-Based Devices Near the Recurrent Laryngeal Nerve

Abstract

Technological advances in thyroid surgery have rapidly increased in recent decades. Specifically, recently developed energy-based devices (EBDs) enable simultaneous dissection and sealing tissue. EBDs have many advantages in thyroid surgery, such as reduced blood loss, lower rate of post-operative hypocalcemia, and shorter operation time. However, the rate of recurrent laryngeal nerve (RLN) injury during EBD use has shown statistically inconsistent. EBDs generate high temperature that can cause iatrogenic thermal injury to the RLN by direct or indirect thermal spread. This article reviews relevant medical literatures of conventional electrocauteries and different mechanisms of current EBDs, and compares two safety parameters: safe distance and cooling time. In general, conventional electrocautery generates higher temperature and wider thermal spread range, but when applying EBDs near the RLN adequate activation distance and cooling time are still required to avoid inadvertent thermal injury. To improve voice outcomes in the quality-of-life era, surgeons should observe safety parameters and follow the standard procedures when using EBDs near the RLN in thyroid surgery

Effects of Intraoperative Neural Tunnel in Protecting Recurrent Laryngeal Nerve: Experiences in Open, Trans Breast, and Transoral Endoscopic Thyroidectomy

“…Furthermore, the “liquid–gas flow” generated by EBDs can also be a risk factor for RLN thermal injury ( 9 , 14 ). RLN thermal injury is severe and can lead to paralysis of the VC ( 15 , 16 ). Notably, it would be quite effective to isolate the RLN with lateral thermal spread and liquid–gas flow.…”

Improving Voice Outcomes after Thyroid Surgery and Ultrasound-Guided Ablation Procedures

“…With the modernization of thyroid surgery, advances have included the use of energy-based devices (EBD) as an extension from the “clamp-and-tie” technique that Theodore Kocher fathered in the 19th century. Today, hemostasis can be achieved in multiple ways: clamp-and-tie, electrocautery (monopoloar or bipolar), with hemostatic clips, and more advanced EBD that use thermal, ferromagnetic, or ultrasonic energy to ligate, seal and dissect tissue ( 36 ). Even though more advanced techniques with EBD have demonstrated reduced pain, wound drainage, decreased rates of neck hematoma and even hypocalcaemia ( 37 – 40 ), the results for EBD are inconsistent in terms of rates of RLN injury compared with conventional approaches ( 41 , 42 ).…”

“…Several studies have demonstrated that traction and thermal injury are the first and second most common causes of iatrogenic RLN injury during thyroidectomy ( 39 , 43 , 44 ). As one would expect, the use of EBDs can generate high temperatures that can spread to critical structures such as the RLN causing indirect thermal spread or direct thermal injury ( 36 ). Thus, various guidelines are published to ensure that surgeons maintain a safe distance between the activated EBD tip and the surrounding soft tissue ( 36 ).…”

“…As one would expect, the use of EBDs can generate high temperatures that can spread to critical structures such as the RLN causing indirect thermal spread or direct thermal injury ( 36 ). Thus, various guidelines are published to ensure that surgeons maintain a safe distance between the activated EBD tip and the surrounding soft tissue ( 36 ). It is also recommended that enough time lapses for the tip or blade to cool sufficiently before using the device to dissect tissue or work close to the RLN.…”

“…Studies have demonstrated that thermal injury can cause irreversible changes to the nerve, damaging the endoneurium with temperatures at little as 60 Celsius ( 48 ). Most EBDs reach temperatures that exceed 200 Celsius when they are activated, and more than 350 Celsius with monopolar electrocautery ( 36 ). Additional care should be taken to avoid inadvertent injury to nearby structures when operating in a wet surgical field, as high temperature steam can be generated if the EBD is activated ( 49 ).…”