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NMB: Brain stem reflexes

Nondepolarizing neuromuscular blocking agents (NMBAs) are commonly used medications in the operating room. By competing with acetylcholine, these drugs bind to alpha subunits on nicotinic acetylcholine receptors to produce their effects. The effect of these medications is predominantly in the periphery, but may exert effects centrally, as well. Sakuraba et al demonstrated NMBAs exerting effects on respiratory control in the brainstem in neonatal rats. Thus, these drugs can impact neuronal acetylcholine receptors. Brainstem reflexes, however, may be preserved in patients receiving NMBAs. Brain stem auditory evoked potential, latency and amplitude of the cortical visual evoked potential, the latency of the spinal cord response, and the latency and amplitude somatosensory evoked potentials are not affected by NMBAs.

As NMBAs function at striated smooth muscle, reflexes which utilize smooth muscle (i.e. pupillary response) will also be preserved.


  1. Sakuraba S, Kuwana S, Ochiai R, et al. Effects of neuromuscular blocking agents on central respiratory control in the isolated brainstem-spinal cord of neonatal rat. Neurosci Res. 2003 Nov;47(3):289-98. Link
  2. Sloan TB. Nondepolarizing neuromuscular blockade does not alter sensory evoked potentials.J Clin Monit. 1994 Jan;10(1):4-10. Link