Page 55 - GTM-2-2

Global Translational Medicine New insights into chronic pain management

Chronic pain develops after an injury or a disease, loses
signal value, and begins to exist according to its own
rights without accompanying symptoms of other diseases.
Chronic pain is maladaptive and has no beneficial
biological significance and is characterized by spontaneous
pain as well as evoked pain in response to noxious or non-
noxious stimuli [3-5] .
Chronic pain differs in terms of their biology,
pathogenesis, clinic, treatment, and prognosis [6,7] . The
pathogenesis of chronic pain includes interactions between
sensory, autonomic, motor, emotional, and cognitive
spheres. Key mechanisms of pain consist of neuronal
plasticity and peripheral sensitization in primary sensory
neurons of dorsal root ganglia and trigeminal ganglia [8-10]
and central sensitization in pain processing neurons of
the spinal cord and brain [11-13] . The core of the pathogenic
mechanism of pain is functional changes in the central
nervous system (CNS) participating in pain control, that Figure 1. Current chronic pain model. Biopsychosocial model of chronic
is, descending noradrenergic and serotoninergic system. pain describes pain and disability as a multidimensional, dynamic
integration among physiological, psychological, and social factors that
This phenomenon is referred to as “augmented central influence one another. The main contributing conditions for chronic pain
pain processing” or “disturbance of sensory processioning are psychosocial factors.
information” . Reorganization in the antipain system
[14]
at the neurochemical level appears serotonin and The role of psychological factor was indicated in recent
noradrenalin imbalance and serotoninergic brainstem systematic reviews, where chronic pain patients report
pathways influence on 5НТ3 spinal nerve receptors . about negative affect statistically more often than pain-
[15]
The biopsychosocial model of pain dominates the free controls [30-32] . Influence of premorbid personality
scientific community’s understanding of chronic pain and psychological characteristics as a risk factor for
(Figure 1). Primary factors leading to chronic pain the development of chronic pain was detected in
development are not identifiable pathology or distraction, musculoskeletal and functional pain models in prospective
but psychological, social, and emotional stress . These studies [18,33-36] . Twenty-month longitudinal study indicated
[16]
can explain that the antipain supraspinal structures, such that the most often psychopathological syndromes
as anterior cingulate cortex, right dorsolateral prefrontal predicted chronic pain and the pain-related disability
cortex, left middle frontal gyrus, and left lateral occipital were depression and anxiety . Psychological distress also
[21]
cortex, as well as periaqueductal gray (PAG) region and promotes pain chronicity and disability.
basal main functions, regulate cognition, emotional One of the main ways of controlling chronic
processes, and behavior [6,7] . These interactions shed light pain is targeting CNS mechanisms that influence its
on the inseparable affinity between nociception and neuroplastic changes, particularly the descending
patients behavior, including mood changes when chronic noradrenergic and serotoninergic system. Tricyclic
pain develops .
[16]
antidepressant (amitriptylin) was the first treatment
Affective disorders such as depression, anxiety, and used in fibromyalgia, a classical type of chronic pain. The
distress are among the most potent and robust predictors of trials demonstrated pain reversal, fatigue decrease, and
the transition from acute to chronic pain [17-19] . Psychosocial sleep disorder normalization in fibromyalgia patients [37] .
processes either exist within an individual as pre-existing Randomized, double-blind, and placebo-controlled
“vulnerability” factor (e.g., distress [20-22] , trauma [23,24] ) or trial indicated low efficacy of selective serotonin
emerge for the first time in response to the experience reuptake inhibitors (SSRI) (e.g., fluoxetine, sertraline,
of ongoing pain (e.g., fear-avoidance behavior , self- citalopram, and paroxetine) in fibromyalgia. Serotonin
[25]
efficacy [26,27] ). These psychosocial factors then influence and noradrenaline reuptake inhibitor (venlafaxine,
individual variability in pain-related outcomes. duloxetine, and milnacipran) were more effective than
The most common psychological factors that can SSRI. Medications of this group, such as tricyclics,
develop persistent pain are depression, anxiety, emotional inhibit the serotonin (5-hydroxytryptamine or 5HT) and
distress, negative emotions, thoughts, and behavior [28-30] . the noradrenalin transporters, but do not influence other

Volume 2 Issue 2 (2023) 2 https://doi.org/10.36922/gtm.312