New Developments in the Understanding of Persistent Pain
New Developments in the Understanding of Persistent Pain
Purpose of review It is proposed that central rather than peripheral factors may be important in pain chronicity. We review recent empirical findings on these processes and discuss implications for treatment and prevention.
Recent findings The literature on neuroimaging of pain and on learning processes shows that learning-induced functional and structural brain changes involving sensorimotor, as well as limbic and frontal, areas are important in the transition from acute to chronic pain. These alterations share many similarities with brain changes in emotional disorders and the specificity for pain needs to be determined. Further important contributors to chronic pain may be disturbed processing of the body image, impaired multisensory integration and faulty feedback from interoceptive processes. These findings have led to new treatment approaches that focus on the extinction of aversive memories, restoration of the body image and normal brain function and include approaches such as brain stimulation, mirror training, virtual reality applications or behavioral extinction training.
Summary We propose that chronic pain is characterized by learning-related and memory-related plastic changes of the central nervous system with concomitant maladaptive changes in body perception. These alterations require new treatments that focus on the alteration of central pain memories and maladaptive body perception.
Recent scientific evidence suggests that chronic pain is greatly determined by learning processes that are accompanied by plastic changes on multiple levels of the nervous system. A fundamental distinction of memory mechanism is that of implicit or nondeclarative and explicit or declarative memory processes. Implicit memory processes refer to often nonconscious changes in behavior as a consequence of experience and involve nonassociative learning such as habituation and sensitization but also associative processes such as operant and respondent conditioning. Explicit learning usually refers to semantic and episodic memory processes that rely on the conscious reproduction of an encoded memory item. These memory processes also involve different brain structures and neuronal networks and may be differentially interacting in health and disease. For example, explicit memory depends on intact hippocampal structures, whereas some types of implicit emotional memory require an intact amygdala or striatum. Although both types of learning and memory processes are important in chronic pain, we have proposed that implicit learning processes may be more pronounced in chronic pain. As implicit learning processes change behavior without the person knowing about it, they may, therefore, be especially difficult to extinguish. We assume that the extinction or 'unlearning' rather than the acquisition of pain memories is the main problem in chronic pain; central and peripheral memory traces are closely interwoven and lead to alterations in the body image; and treatment can be viewed as extinction and relearning and needs to be provided on the basis of learning principles.
Abstract and Introduction
Abstract
Purpose of review It is proposed that central rather than peripheral factors may be important in pain chronicity. We review recent empirical findings on these processes and discuss implications for treatment and prevention.
Recent findings The literature on neuroimaging of pain and on learning processes shows that learning-induced functional and structural brain changes involving sensorimotor, as well as limbic and frontal, areas are important in the transition from acute to chronic pain. These alterations share many similarities with brain changes in emotional disorders and the specificity for pain needs to be determined. Further important contributors to chronic pain may be disturbed processing of the body image, impaired multisensory integration and faulty feedback from interoceptive processes. These findings have led to new treatment approaches that focus on the extinction of aversive memories, restoration of the body image and normal brain function and include approaches such as brain stimulation, mirror training, virtual reality applications or behavioral extinction training.
Summary We propose that chronic pain is characterized by learning-related and memory-related plastic changes of the central nervous system with concomitant maladaptive changes in body perception. These alterations require new treatments that focus on the alteration of central pain memories and maladaptive body perception.
Introduction
Recent scientific evidence suggests that chronic pain is greatly determined by learning processes that are accompanied by plastic changes on multiple levels of the nervous system. A fundamental distinction of memory mechanism is that of implicit or nondeclarative and explicit or declarative memory processes. Implicit memory processes refer to often nonconscious changes in behavior as a consequence of experience and involve nonassociative learning such as habituation and sensitization but also associative processes such as operant and respondent conditioning. Explicit learning usually refers to semantic and episodic memory processes that rely on the conscious reproduction of an encoded memory item. These memory processes also involve different brain structures and neuronal networks and may be differentially interacting in health and disease. For example, explicit memory depends on intact hippocampal structures, whereas some types of implicit emotional memory require an intact amygdala or striatum. Although both types of learning and memory processes are important in chronic pain, we have proposed that implicit learning processes may be more pronounced in chronic pain. As implicit learning processes change behavior without the person knowing about it, they may, therefore, be especially difficult to extinguish. We assume that the extinction or 'unlearning' rather than the acquisition of pain memories is the main problem in chronic pain; central and peripheral memory traces are closely interwoven and lead to alterations in the body image; and treatment can be viewed as extinction and relearning and needs to be provided on the basis of learning principles.
