PURPOSE

Extreme lateral interbody fusion (XLIF) is a method for stabilization of the lumbar spine. Intraoperatively, the surgeon identifies the lumbar nerve roots with a stimulator to prevent their injury. The objective of this study was to determine the extent to which shallow rocuronium-induced neuromuscular block must be intraoperatively reversed for reliable identification of nerve roots.

METHODS

General anesthesia (midazolam-propofol-sufentanil-oxygen/air/sevoflurane-rocuronium) was administered to all patients. Train-of-four (TOF) stimulation of the ulnar nerve at 15-s intervals and electromyographic response of the adductor pollicis muscle were used. During operation, the surgeon stimulated the lumbar nerve roots (5-10 mA) to identify their course. At the appearance of two twitches to the TOF stimuli, sugammadex (2 mg/kg) or neostigmine (0.04 mg/kg) was administered. When the response to nerve root stimulation appeared, the TOF ratio was recorded.

RESULTS

When the response to nerve root stimulation with 10 mA became detectable, the median (range) TOF ratios were 0.67 (0.50-0.81) and 0.65 (0.42-0.71) after sugammadex and neostigmine, respectively. Similarly, TOF ratios at the first detectable response to stimulation with 5 mA were 0.88 (0.67-0.93) and 0.83 (0.61-0.93). After sugammadex and neostigmine, the respective intervals until TOF ratio ≥0.90 were 2.0 (0.8-3.3) and 15.9 (7.3-28.8) min.

CONCLUSION

Intraoperative reversal of shallow rocuronium-induced block with either sugammadex or neostigmine is an efficient method. For reliable detection of lumbar nerve roots with a stimulating current of 10 mA, the block should be reversed to a TOF ratio of at least 0.70. For a current intensity of 5 mA, the TOF ratio should reach 0.90.