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What is Electromyography (EMG)?

Electromyography EMG measures the electrical signal during depolarization at the neuromuscular junction. The muscle action potential is the electrical signal that can be measured after neuromuscular transmission.

Tetragraph EMG monitor is a better indicator of adequate recovery from neuromuscular block and readiness for safe tracheal extubation than the acceleromyography monitor.

Nemes et al | Anesthesiology 2021

Ipsilateral and Simultaneous comparison of responses from Acceleromyography- and Electromyography- based Neuromuscular Monitors

Any place, any case

With TetraGraph EMG technology, you can easily and accurately assess your patients’ depth of paralysis to guide your decisions during any case, regardless of arm position or placement under surgical drapes that may interfere with the anesthesiologist’s access.

  • Robotic surgery 
  • Laparoscopy 
  • Neurosurgical 
  • Orthopedic
  • Thoracic 

TetraGraph EMG vs. AMG

  • TetraGraph measures the compound muscle action potentials (CMAPs), which are indicative of neuromuscular receptor function; these are reliable physiologic signals that can be measured
  • EMG is the ONLY technique that does not rely on or require thumb movement. No motion is measured with EMG
  • TetraGraph can be used in all types of surgeries and any patient position
  • TetraGraph provides reliable measurements regardless of involuntary patient movements in patients emerging from anesthesia
  • AMG requires normalization due to reverse fade phenomenom, this is not required with EMG

EMG – The new Gold Standard in NMT monitoring

Like other technologies, EMG involves stimulation of a peripheral nerve and measurement of the response that is generated by the contraction of the innervated muscle. The difference from other technologies is that EMG measures an electrical event that occurs at the neuromuscular junction; the activation of postsynaptic receptors by acetylcholine (a chemical process) that converts it to a mechanical response (excitation- contraction coupling), that results in muscle contraction. Because measurement of function does not depend on physical movement (as MMG, AMG or KMG require), EMG is a better indicator of pure neuromuscular function- EMG is the new gold standard.

Why EMG?

EMG measures the first signal


EMG measures the first signal

EMG is the only technique that measures the compound muscle action potential (CMAP). The muscle action potential is the first signal that can be measured after neuromuscular transmission. 

No overestimated recovery


No overestimated recovery

It has been demonstrated in clinical publications that other techniques, such as KMG and AMG tend to overestimate the degree of neuromuscular recovery compared to electromyography (EMG).

Arm can be tucked

No Limitations

Arm can be tucked

EMG techniques can be used independently of the hand position and does not require free movement of the thumb. 

EMG tells the story

Neuromuscular Transmission Stages and Related Neuromuscular Transmission Technologies

Neuromuscular Transmisson (NMT) is the transfer of an impulse between a nerve and a muscle across neuromuscular junction. EMG measures the compound action potential, which is the first signal we are able to measure during neuromuscular transmission. Therefore, EMG is most specifically suited to monitor the effect of muscle relaxants without any mechanical interferences.

  • Action potential

  • Acetylcholine release

  • Channel opening

  • Endplate potential

  • Depolarization
    Muscle membrane

    EMG measurement

  • Electromechanical coupling

  • Muscle contraction

    • Tactile measurement
    • MMG measurement
    • AMG measurement
    • KMG measurement
    • CMG measurement


Nemes et al- Ipsilateral and Simultaneous comparison of responses from Acceleromyography- and Electromyography- based Neuromuscular Monitors, Anesthesiology 2021 Oct 1;135(4):597-611

Lee W. -The latest trend in neuromuscular monitoring; return of the electromyography, Anesth Pain Med 2021 April 30;16 (2):133-137

Murphy G.S, Brull S.J- Quantitative Neuromuscular Monitoring and Postoperative Outcomes: A Narrative Review, Anesthesiology 2022 Feb 1;136(2):345-361

Renew J.R et al- Comparison of the TetraGraph and TOFscan for monitoring recovery from neuromuscular blockade in the Post Anesthesia Care Unit, Journal of Clinical Anesthesia 71 (2021) 110234

Salminen J et al. Comparison of train-of-four ratios measured with Datex-Ohmeda´s M-NMT mechano-sensor and M-NMT electro-sensor. Journ of Clin Monitoring and Computing, 2016; 30(3),295-300

Naguib M, et al. Consensus Statement on perioperative Neuromuscular Monitoring. Anest Analg. 2018; 127(1):71-80

Naguib et al. Conceptual and technical insights into the basis of neuromuscular monitoring. Anaesthesia 2017;72:16-37

Liang SS, et al. An ipsilateral comparison of acceleromyography and electromyography during recovery from nondepolarizing neuromuscular block under general anesthesia in Humans. Anesth Analg 2013; 117:373-9

Murphy GS. Neuromuscular Monitoring in the Perioperative Period. Anesth Analg 2018; 126:464-468

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