Cortical activity evoked by an acute painful tissue-damaging stimulus in healthy adult volunteers

Abstract

Everyday painful experiences are usually single events accompanied by tissue damage, and yet most experimental studies of cutaneous nociceptive processing in the brain use repeated laser, thermal, or electrical stimulations that do not damage the skin. In this study the nociceptive activity in the brain evoked by tissue-damaging skin lance was analyzed with electroencephalography (EEG) in 20 healthy adult volunteers (13 men and 7 women) aged 21–40 yr. Time-frequency analysis of the evoked activity revealed a distinct late event-related vertex potential (lance event-related potential, LERP) at 100–300 ms consisting of a phase-locked energy increase between 1 and 20 Hz (delta-beta bands). A pairwise comparison between lance and sham control stimulation also revealed a period of ultralate stronger desynchronization after lance in the delta band (1–5 Hz). Skin application of mustard oil before lancing, which sensitizes a subpopulation of nociceptors expressing the cation channel TRPA1, did not affect the ultralate desynchronization but reduced the phase-locked energy increase in delta and beta bands, suggesting a central interaction between different modalities of nociceptive inputs. Verbal descriptor screening of individual pain experience revealed that lance pain is predominantly due to Aδ fiber activation, but when individuals describe lances as C fiber mediated, an ultralate delta band event-related desynchronization occurs in the brain-evoked activity. We conclude that pain evoked by acute tissue damage is associated with distinct Aδ and C fiber-mediated patterns of synchronization and desynchronization of EEG oscillations in the brain.

Neurophysiological assessment of acute pain in infants: a scoping review of research methods

“…In the studies conducted to date, the quantification of EEG ERPs has been completed with the highest degree of methodological consistency, complying with reporting standards for publication of ERP studies , and has consistently described a pain‐specific marker of central nervous system pain processing. While only one study has been published examining nociceptive ERPs evoked by a tissue damaging lance in adults, and the lance was applied to the palmar surface of the distal phalanx of the fifth finger as opposed to the lateral or medial aspect of the heel as in the infant studies, the findings of this study are consistent with the infant literature in that adults did demonstrate a distinct negative–positive ERP that presented at electrode site Cz approximately 100–300 ms after painful stimulus . The two studies that attempted to quantify infant emotional response to pain using left‐right EEG asymmetry found no evidence for reliable pain‐specific changes in EEG power or asymmetry indices, despite the detection of pain using behavioural measures .…”

“…Additionally, several of the studies appear to include the same infants across studies, which raises concerns related to potential selection bias as this was not reported. While the limited research utilising this method in adults have similar sample sizes , future research aiming to advance our understanding of optimal samples sizes to detect neurophysiological differences is needed.…”

What do we really know about newborn infant pain?

“…Electroencephalography, in contrast, is a non-invasive neurophysiological method that records the electrical activity of the brain at the scalp, largely from superficial regions, such as the somatosensory cortex, because voltage changes dissipate from deeper subcortical structures over a certain distance. It is possible to observe event-related changes in the EEG traces following certain stimuli, including noxious laser, pinprick and heel lance (Zhang et al 2012;Fabrizi et al 2013;Iannetti et al 2013). Recently, studies have identified an event-related potential in newborn infants and infants up to 1 year old, which is specific to noxious stimulation (Slater et al 2010b,c;Fabrizi et al 2011;Verriotis et al 2015).…”

Differential Suppression of Spontaneous and Noxious-evoked Somatosensory Cortical Activity by Isoflurane in the Neonatal Rat

“…Extracellular field recording, including electroencephalogram (EEG), electrocorticogram (ECoG) and local field potentials (intracortical activity) are commonly used to monitor ongoing spontaneous brain activity and levels of anesthesia in human and rodent neonates but are also used to record specific potentials evoked by a sensory stimulus. Somatosensory potentials evoked by experimental noxious cutaneous stimulation [8][9][10][11] are commonly used to measure pain activity in the adult human and rodent brain 12 . Specific nociceptive potentials are also evoked by single, clinically required skin breaking procedures in the human infant brain 13,14 and have been used in this age group to measure the postnatal development of cortical pain processing 10 .…”