Intraoperative Nerve Monitoring Could Cause Heart Attack

Stimulation of the vagus nerve as part of intraoperative neuromonitoring (IONM) during thyroid surgery can result in severe cardiac complications, according to two new case reports.

Researchers at Skane University Hospital (Lund, Sweden) presented their findings on IONM of the recurrent laryngeal nerve in two patients. The first patient was an 81-year-old woman with type 2 diabetes and hypertension who was admitted for parathyroid surgery due to primary hyperparathyroidism. Following vagal stimulation with a 1 mA electrical current profound bradycardia occurred, which proceeded to cardiac arrest within a few seconds.

The sinus rhythm recovered after cardiopulmonary resuscitation (CPR) with external heart massage and atropine and ephedrine administration. The second patient was a 76-year-old man who was undergoing thyroid surgery to remove a large lesion in the neck. After 1 mA electrical current stimulation of the vagal nerve during dissection, the patient experienced asystole. He responded to intravenous ephedrine and cardiac massage. The case reports were published online on February 1, 2016, in Head & Neck.

“These two cases demonstrate that stimulation of the vagus nerve during intraoperative neuro-monitoring can lead to profound cardiac events,” concluded lead author Martin Almquist, MD, PhD, and colleagues. “Consideration should be given to these potential complications when utilizing IONM.”

IONM involves the use of electrophysiological methods such as electroencephalography (EEG), electromyography (EMG), and evoked potentials to monitor the functional integrity of neural structures during surgery. The purpose of IONM is to reduce the risk to the patient of iatrogenic damage to the nervous system, and to provide functional guidance to the surgeon and anesthesiologist.

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Skane University Hospital