“…Furthermore, the 1 mA stimulation current used for CIONM is not believed to engender concomitant or subsequent adverse vagal effect leading to central (headache, numbness), cardiac (arrhythmias, bradycardia), pulmonary (bronchospasm), or gastrointestinal (nausea, vomiting) symptoms (9,11,15,17,26,27,30,31). Studies (22,25) that applied stimulation current up to 5.0 mA for CIONM, observed an increased variability in heart rate, implying autonomic nervous system imbalance. The elicited parasympathetic activation was not associated with a compensatory increase in sympathetic activity and remained subclinical.…”