As neuromuscular blockade during LSR monitoring decreases the amplitude of EMG, partial neuromuscular blockade is usually maintained during general anesthesia for MVD. However, there have been no evidence of which degree of partial neuromuscular blockade should be performed or no neuromuscular blockade could be performed during LSR monitoring. Therefore, we performed a randomized controlled trial to evaluate the effect of different degree of partial neuromuscular blockade, including no neuromuscular blockade on the LSR monitoring for MVD surgery.