30 June 2026 : Review article
Muscle-Specific Differences in Neuromuscular Block and Quantitative Neuromuscular Monitoring: A Narrative Review
Paweł Radkowski
ABCDEFG 1,2,3, Dawid Kamil Malicki BCDEF 4, Florian Trachte CDEF 5,6, Hubert Oniszczuk CDEF 7*
DOI: 10.12659/MSM.951168
Med Sci Monit 2026; 32:e951168
Introduction
Neuromuscular Conduction
Measurement of Neuromuscular Transmission Depending on Muscle Group: The TOF Method
Adductor Pollicis Muscle
Diaphragm
Muscles of the Arm and Forearm
Orbicularis Oculi Muscle
Corrugator Supercilii Muscle
Laryngeal Muscles
Pharyngeal Muscles
TOF-Cuff Measurements on the Lower Leg
Foot Muscles
Discussion
Future Directions
Conclusions
References
Table 3 Comparison of facial and peripheral monitoring sites: relationship to laryngeal adductor behavior and clinical interpretation.
| Muscle monitored | Correlation with laryngeal adductor muscles | Onset of blockade vs adductor pollicis | Resistance to NMBAs | Recovery vs adductor pollicis | Reversal characteristics | Main clinical role |
|---|---|---|---|---|---|---|
| Corrugator supercilii | Strong | Later onset | Higher resistance | Faster recovery | Lower dose of sugammadex sufficient (eg, ~2 mg/kg) | Best facial predictor of intubating conditions |
| Orbicularis oculi | Moderate | Earlier onset | Moderate resistance | Faster recovery | TOF=1.0 may occur with residual block | Useful for onset only; unsafe for extubation |
| Adductor pollicis | Poor (airway muscles) | Reference | Lower resistance | Slowest recovery | Requires higher reversal doses | Gold standard for recovery and extubation |
| NMBA – neuromuscular blocking agent; TOF – train-of-four. Correlation with laryngeal adductor muscles primarily refers to similarity in onset and early recovery of neuromuscular blockade. Recovery at facial sites occurs earlier than recovery at peripheral muscles and does not reliably reflect restoration of pharyngeal or airway-protective muscle function. A TOF ratio of 1.0 measured at the orbicularis oculi does not exclude residual neuromuscular weakness. | ||||||