Central Enhancement of Evoked Electromyographic Monitoring of Neuromuscular Function †

Abstract

Central neural influences on neuromuscular transmission may explain the frequent failure of evoked electromyographic (EEMG) responses to return to control values during offset of neuromuscular block. This study, performed in conscious subjects, did not demonstrate any change in EEMG response of either the first dorsal interosseous muscle during onset of ulnar nerve block or the flexor hallucis brevis during onset of subarachnoid block. It is concluded that central enhancement of EEMG response via a neural mechanism does not explain the observed failure of EEMG monitoring of neuromuscular block.

Differential effect of pancuronium at the adductor pollicis, the first dorsal interosseous and the hypothenar muscles. An electromyographic and mechanomyographic dose‐response study

“…EEMG amplitude and duration of the three muscles in our study were greater than those found by Kalli (24). A baseline drift of the EEMG has been described during the first 1&15 min from induction of anaesthesia (25,26). We did, however, not observe any drift in the EEMG during a post-induction period of 8-10 min before administration of pancuronium.…”

Effect of three anaesthetic techniques on isometric skeletal muscle strength

“…Whereas the main part of this central sympathetic out¯ow innervates organs such as the heart, lungs, sweat glands, and skin, only a minor component reaches the skeletal muscle and has no measurable in¯uence on muscle tone, as was demonstrated by Smith during spinal anaesthesia. 24 Moreover, during static exercise in humans, central command was found to contribute very little to the activation of sympathetic out¯ow in skeletal muscle. 25 However, peripheral afferent impulses from muscle mechanoreceptors (muscle spindles), Golgi tendon organs, and chemosensitive endings in muscles in¯uence sympathetic nerve activity and skeletal muscle tension by re¯ex mechanisms.…”

Influence of serum concentrations of catecholamines and i.v. or volatile anaesthesia on evoked electromyography in the hand

“…The decrease in the baseline EEMG response which occurs during general anaesthesia is currently unexplained, but previous work has shown that it is not caused by the central neural effects of general anaesthesia [7], changes in the impedance of the electrodes used to record the EMG [10] or changes in skin or muscle temperatures [11]. The decrease in the EEMG response also does not seem to occur in awake subjects [7].…”

“…Evoked electromyographic (EEMG) monitoring of neuromuscular function is unreliable in 5-42% of patients because the first response (Tl) to train-offour (TOF) stimulation does not return to the preblock baseline value during the offset of neuromuscular block [1][2][3]. A decrease in the Tl response of the EEMG also occurs during the first 15-20 min of general anaesthesia without neuromuscular blocking agents [4][5][6], but not in awake volunteers [7]. The reasons why the EEMG response decreases during anaesthesia are unknown, but changes in serum concentrations of catecholamines during anaesthesia are one possible cause [8].…”