Experts debate benefits of routine nerve monitoring in thyroid surgery

Issue: October 2012

QUEBEC CITY — Although many clinicians use intraoperative nerve monitoring during thyroid surgery, data do not necessarily associate the practice with improved outcomes. The question of whether it should be used routinely was up for discussion at the American Thyroid Association 82nd Annual Meeting.

Potential benefits

Jennifer E. Rosen, MD, FACPS, assistant professor of surgery and molecular medicine at Boston University School of Medicine, said that nerve monitoring may be beneficial from a cost standpoint, explaining that post-operative permanent nerve injury and post-operative permanent hypothyroidism are the driving force behind the majority of lawsuits in thyroid surgery.

She also highlighted several uses for intraoperative nerve monitoring in thyroidectomy. For instance, it offers more than visual confirmation when identifying the recurrent laryngeal nerve, Rosen said. Additionally, nerve monitoring can help identify abnormalities in the anatomy of the nerve and aid in dissection. Further, she noted, nerve monitoring has value as a prognostic tool in terms of postoperative neural function.

The major question, however, is whether intraoperative nerve monitoring prevents nerve injury or paralysis during thyroidectomy. Although data are not completely positive, this may be due to several factors, according to Rosen, such as whether the surgeon performs pre-operative and post-operative laryngoscopy and in what setting; how many procedures the surgeon performs per year; what techniques are used; and more.

If a surgeon is going to use nerve monitoring, he or she should do it routinely, Rosen said. The surgeon should also perform pre- and post-operative laryngoscopy and voice assessment, as well as be very aware and knowledgeable about the type of equipment and approach to surgery that is being used.

“Based on the preponderance of evidence and an interpretation of the strengths and limitations of the data on which we base our decisions, and with some qualifications based on the type of surgery, the setting and the surgeon, then yes, [intraoperative nerve monitoring] should be done routinely,” she said.

A lack of data

However, David J. Terris, MD, FACS, Porubsky Professor and chairman of the department of otolaryngology at Georgia Health Sciences University and surgical director of the Thyroid Center, pointed out that the published scientific evidence does not support the routine use of nerve monitoring in thyroid surgery.

“It’s important to consider this in two different ways: what is the logic behind nerve monitoring vs. what about the data actually supporting the use of nerve monitoring? We want to consider those separately,” he said.

Terris cited four studies that failed to prove a connection between nerve monitoring and improved functional outcomes in thyroid surgery. For example, results from a trial conducted at 63 centers in Germany and involving 29,998 nerves demonstrated no differences in the nerve monitoring group when compared with the nerve identification and dissection group (although each of these methods were superior to an approach where the nerve is not sought and identified) . Similarly, researchers for another study involving 1,804 nerves at risk concluded no benefit to nerve monitoring (although both nerve monitoring and nerve stimulation and twitch palpation without nerve monitoring were able to predict nerve injury).

The potential for added costs, including a $300 endotracheal tube, additional time in the operating room and from $500 to $1,000 in surgical fees, is another possible downside to nerve monitoring, according to Terris. Complications such as airway obstruction, tongue necrosis and increased parasympathetic tone associated with clamping the vagus nerve are also concerns, he said. Moreover, clinicians may become reliant on the technology for identifying the nerve.

“One concern is training a new generation of surgeons who have inferior anatomical skills,” he said. “The bottom line is that [nerve monitoring] adds expense; has its own potential for complications; induces a false sense of security; and there’s no evidence that it does what it’s supposed to do, which is prevent injury.” Despite these shortcomings, Dr. Terris indicated that he himself generally uses nerve monitoring because of subtle advantages associated with it, and incremental surgical information that it provides. – by Melissa Foster

For more information:
Rosen J. Advances in thyroid surgery — two debates: Should nerve monitoring be used routinely? Presented at: the American Thyroid Association 82nd Annual Meeting; Sept. 19-23, 2012; Quebec City.

Disclosure: Rosen reports no relevant financial disclosures. Terris has directed thyroid courses sponsored by Johnson & Johnson.