MEP and EMG monitoring are highly sensitive to neuromuscular blockade, making complete paralysis unsuitable for these procedures. To ensure effective monitoring, the use of neuromuscular blocking agents (NMBAs) must be planned in close coordination with the surgical and monitoring teams. For endotracheal intubation where neuromonitoring will follow shortly, a short-acting NMBA or none at all is recommended. Succinylcholine is often chosen for its rapid recovery, though alternatives or non-NMBA methods should be used for patients who cannot receive succinylcholine. When using rocuronium or vecuronium, rapid reversal with sugammadex might be necessary but could complicate further muscle relaxation needs during the procedure.
Intermediate-duration nondepolarizing NMBAs like rocuronium, vecuronium, and cisatracurium are appropriate when immediate baseline neuromonitoring is not needed. These agents are beneficial for surgeries such as craniotomies, where initial paralysis aids in positioning, but it is essential to ensure relaxation has worn off before monitoring begins.
Throughout surgery, nondepolarizing NMBAs should either be avoided or meticulously monitored during EMG monitoring. During MEP monitoring, it's crucial to maintain enough neuromuscular function for accurate readings while also ensuring sufficient relaxation to prevent movement. Paralysis levels should be monitored continuously with a train-of-four (TOF) peripheral nerve stimulator, targeting two of four twitches or a single twitch at 10-20% of baseline. When TOF monitoring is impractical due to surgical positioning, neuromonitoring technologists can measure TOF in specific muscles being monitored, recognizing that NMBA effects may differ between muscle groups.
