Nerve Monitoring Program


Voice Preservation in Thyroid Surgery

Surgery on the thyroid gland requires special attention and expertise because of the close proximity of the thyroid to the recurrent laryngeal nerves (nerves that power the vocal cords). The vocal cords rest within the larynx in the neck and move as we speak, swallow, and breathe. If the nerves that innervate these structures are damaged during thyroid surgery, the patient’s ability to speak, swallow, and breathe can be significantly affected.

This complication, recurrent laryngeal nerve injury, occurs in up to 5 to 10 percent of thyroid surgeries nationally. Injury can occur on one side (when surgery is performed on one side of the thyroid) or on both sides (if the entire thyroid is removed). This can lead to vocal cord paralysis, a very significant complication of thyroid surgery.

Thyroid anatomy diagram

If the nerve is injured on only one side, patients typically experience a reduction in the power of their voices, often resulting in a breathy voice, which sometimes sounds like a whisper. They may also experience swallowing problems, termed “dysphagia.” Patients with dysphagia can cough when they drink and sometimes when they eat solid food. Since a functioning vocal cord also serves to protect the airway, coughing can also occur when saliva mistakenly travels into the airway, even when the patient is not eating. 

If the recurrent laryngeal nerve is injured on both sides, breathing can be dangerously affected. With bilateral paralysis, the vocal cords come to rest in the midline and the patient’s breathing is usually severely impaired. In these cases, patients often require tracheotomy tubes to breathe. 

In addition to the recurrent laryngeal nerves, the superior laryngeal nerve, a branch of the recurrent laryngeal nerves, is also susceptible to injury. In these cases, voice projection, especially when singing, and the upper registers of voice can be affected, making thyroid surgery especially intimidating for professional voice artists. 

A pioneer in voice preservation during thyroid surgery, Dr. Gregory Randolph of Mass. Eye and Ear developed and researched neural monitoring technology to stimulate these nerves and to monitor their function during surgery. He has written numerous research articles, authored two textbooks, and directs surgical education courses at Harvard Medical School, teaching surgeons throughout the country and around the world techniques of neural monitoring during thyroid surgery. Our surgeons routinely use nerve monitoring technology during thyroid and parathyroid surgery. Nerve monitoring technicians reviewing neural output during thyroid surgery. Nerve monitoring technicians reviewing neural output during thyroid surgery. 

Here at Mass. Eye and Ear, we have a unique nerve monitoring program in which highly trained technicians monitor the nerve signals in the operating room and communicate directly with the operating surgeon during the procedure. In many hospitals where nerve monitoring is also performed, the surgeon must not only concentrate on the surgery but must perform the nerve monitoring function themselves simultaneously. Our program allows surgeons to concentrate on the surgical procedure while technicians are expertly monitoring nerve function. 

Our physicians established this program in 1998 and have since performed more than 3,500 successful cases. We share our expertise through global health initiatives around the world, including bringing this monitoring technology to Africa, China, Russia, and India.

Scientific Resources


The drawing on this page was published in Surgery of the Thyroid and Parathyroid Glands, Randolph, GW, Page 736, Copyright Elsevier (2012).