A Brain Signature to Differentiate Acute and Chronic Pain in Rats

Abstract

The transition from acute pain to chronic pain entails considerable changes of patients at multiple levels of the nervous system and in psychological states. An accurate differentiation between acute and chronic pain is essential in pain management as it may help optimize analgesic treatments according to the pain state of patients. Given that acute and chronic pain could modulate brain states in different ways and that brain states could greatly shape the neural processing of external inputs, we hypothesized that acute and chronic pain would show differential effects on cortical responses to non-nociceptive sensory information. Here by analyzing auditory-evoked potentials (AEPs) to pure tones in rats with acute or chronic pain, we found opposite influences of acute and chronic pain on cortical responses to auditory inputs. In particular, compared to no-pain controls, the N100 wave of rat AEPs was significantly enhanced in rats with acute pain but significantly reduced in rats with chronic pain, indicating that acute pain facilitated cortical processing of auditory information while chronic pain exerted an inhibitory effect. These findings could be justified by the fact that individuals suffering from acute or chronic pain would have different vigilance states, i.e., the vigilance level to external sensory stimuli would be increased with acute pain, but decreased with chronic pain. Therefore, this auditory response holds promise of being a brain signature to differentiate acute and chronic pain. Instead of investigating the pain system per se, the study of pain-induced influences on cortical processing of non-nocicpetive sensory information might represent a potential strategy to monitor the progress of pain chronification in clinical applications.

Pain phenotypes classified by machine learning using electroencephalography features

“…Another important factor to consider is the pain state as a variable. The effects of experimentally-induced tonic versus phasic pain on EEG ( Hadjileontiadis, 2015 ; Levitt et al, 2017 ; Misra et al, 2017 ; Vijayakumar et al, 2017 ), as well as resting state versus evoked response potentials (ERP) ( Schulz et al, 2012 ; Huang et al, 2013 ; Bai et al, 2016 ) further clouds the relationship between clinical pain and neocortical oscillations, given that phasic, tonic and chronic pain may have distinct physiological patterns ( Apkarian et al, 2009 ; Guo et al, 2016 ). Other variables that should be controlled for in an EEG study are age and gender.…”

Pharmaceutical and Botanical Management of Pain Associated with Psychopathology: A Narrative Review

“…By contrast, chronic pain has an unlimited duration, lasting more than 3 months. Chronic pain differs from acute pain in the pathophysiological mechanisms and in its temporality in which the adaptive physiological process that characterizes is shown [9][10][11]. In 2019, a new classification of chronic pain was proposed by the World Health Organization (ICD-11) [12], according to its neurophysiological characteristics, as nociceptive, neuropathic, and nociplastic [6,12], see Table 2.…”

Differences in Postural Balance, Pain Sensitivity and Depression between Individuals with Acute and Chronic Back Pain

“…The transition from acute to chronic pain is determined by many pain features and individual characteristics [ 14 ]. In this sense, depression has been considered one of the main risk factors for pain chronification [ 15 , 16 , 17 ]. Thus, it has been reported that depression can predict the persistence of pain in muscle-skeletal injuries [ 18 ], contributes to the transition towards chronic pain [ 19 , 20 , 21 ], and is associated with postural instability in neurological disorders such as stroke [ 14 ] and Parkinson disease [ 20 ], as well as in the elderly [ 22 ].…”