The effect of neuromuscular blockade on pedicle screw stimulation thresholds.

Study Design. Nerve root stimulation thresholds were studied relative to the level of neuromuscular blockade in patients undergoing lumbar decompression surgery. Objectives. To determine what levels of intraoperative neuromuscular blockade can be used during pedicle screw stimulation. Background Data. Previous studies of intraoperative pedicle screw stimulation thresholds have failed to determine the effect of neuromuscular blockade on the stimulation threshold. Methods. Twenty-one roots in 10 patients undergoing lumbar decompression surgery were studied at different levels of neuromuscular blockade. Ninety-five nerve root thresholds were determined relative to level of blockade. Results. Neuromuscular blockade below 80% provides nerve root thresholds similar to thresholds without blockade. Conclusions. Neuromuscular blockade should be less than 80% when using pedicle screw electrical stimulation testing.