Stefan Elbers

12 Chapter 1 ACUTE PAIN VERSUS CHRONIC PAIN From a neuroscientific perspective, the experience of pain is most likely to emerge from an activated pattern of functionally connected cortical areas (Brodal, 2017). This network reaches down via the thalamus, the spinothalamic tract, and peripheral nerve fibers to the nociceptors throughout the body (Brodal, 2017). At numerous levels in this sensory system, the amplitude of the signal can be modified, thereby influencing the pain response (Kosek et al., 2016). In many instances, this flexibility is regarded as an adaptive process (Clauw et al., 2019; McCarberg & Peppin, 2019; Tabor & Burr, 2019). For example, temporary local peripheral sensitization caused by inflammation processes in injured tissues promotes vigilance and behaviours protective of vulnerable tissue during the process of healing (Basbaum et al., 2009). However, alterations in sensitivity independent of tissue damage allow for the possibility of persistent pain without an underlying pathological substrate in local tissues or even the activation of peripheral nociceptors. In these instances, pain loses its warning function and shifts from being a symptom to a disease in its own right. This is reflected in the ICD-11 framework, where pain can be classified as a symptom related to an underlying disease, but also as a disease in itself (Treede et al., 2015, 2019). Importantly, the existence of sensitizing mechanisms across the nociceptive system does not imply that all chronic pain is independent of local pathology. The multiple parenting option of the ICD-11 provides the option to combine multiple categories to classify mixed conditions accordingly. Although neuroscientific studies have provided empirical support for modulating mechanisms across the nociceptive network, the experience and consequences of chronic pain cannot be completely understood through this paradigm (Doleys, 2017). As many authors have discussed, it is not a nervous system that suffers from chronic pain, but a person in interaction with their social context (Doleys, 2017; Eccleston, 2018; Hruschak & Cochran, 2017; Thacker & Moseley, 2012). It is therefore important also to consider the transition from acute to chronic pain through psychological and social lenses. Many studies in the psychological domain have emphasized the importance of associative learning processes in the transition from acute to chronic pain (e.g. Moseley & Vlaeyen, 2015;Vlaeyen et al.,2016).Apain experience demands attention,often interrupting ongoing physical and psychological processes (Berryman et al., 2013; Moore et al., 2019). What follows is an evaluation where people attempt to make sense of the potential threat and decide an appropriate protective response (Seymour, 2019). This process involves making inferences from sensory input (both interoceptive and salient contextual information), combined with previously learned cognitive and emotional associations, such as beliefs and fears (Phelps et al., 2021). Irrespective of the type of response at a particular moment,