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Nature Reviews. Neuroscience Jul 2013Chronic pain is one of the most prevalent health problems in our modern world, with millions of people debilitated by conditions such as back pain, headache and... (Review)
Review
Chronic pain is one of the most prevalent health problems in our modern world, with millions of people debilitated by conditions such as back pain, headache and arthritis. To address this growing problem, many people are turning to mind-body therapies, including meditation, yoga and cognitive behavioural therapy. This article will review the neural mechanisms underlying the modulation of pain by cognitive and emotional states - important components of mind-body therapies. It will also examine the accumulating evidence that chronic pain itself alters brain circuitry, including that involved in endogenous pain control, suggesting that controlling pain becomes increasingly difficult as pain becomes chronic.
Topics: Attention; Brain; Chronic Pain; Cognition; Emotions; Humans; Pain Management; Pain Perception
PubMed: 23719569
DOI: 10.1038/nrn3516 -
Journal of Neurophysiology Jan 2013Several theoretical frameworks have been proposed to explain the physiological basis of pain, although none yet completely accounts for all aspects of pain perception.... (Review)
Review
Several theoretical frameworks have been proposed to explain the physiological basis of pain, although none yet completely accounts for all aspects of pain perception. Here, we provide a historical overview of the major contributions, ideas, and competing theories of pain from ancient civilizations to Melzack and Wall's Gate Control Theory of Pain.
Topics: Animals; History, 17th Century; History, 18th Century; History, 19th Century; History, 20th Century; History, 21st Century; History, Ancient; Humans; Pain; Pain Perception; Sensory Gating
PubMed: 23034364
DOI: 10.1152/jn.00457.2012 -
Current Molecular Pharmacology 2021Pain is often flammable, sharp and sometimes described as an electrical shock. It can be categorized in three different ways as nociceptive, neuropathic and... (Review)
Review
BACKGROUND
Pain is often flammable, sharp and sometimes described as an electrical shock. It can be categorized in three different ways as nociceptive, neuropathic and inflammatory. Nociceptive pain always originates in specific situations such as in trauma. Neuropathic pain results in nerve damage. In inflammatory pain, inflammatory mediators are involved in the sensitization of nociceptors. It is important to control the pain as it affects the individual physically, mentally, and socially.
OBJECTIVE
Recognizing pain physiopathology and pain pathways, defining the relationship between receptor and transmitter is critical in developing new treatment strategies. In this review, current information on the definitions, classifications, and physiological and chemical mechanisms involved in pain are reviewed.
METHODS
Various search engines were used to gather related articles/information. Only peer-reviewed journals were considered. Additional, books/chapters of standard publishers were also included in the article.
RESULTS
With a better understanding of the physiological and chemical mechanisms that play a role in pain, significant improvements have been made in pain treatment. Various oral or intravenous drugs, local injection treatments, physical and occupational therapy, electrical stimulation, alternative medicine applications, psychological support, and surgical applications are routinely performed in the treatment, dependent upon the type, severity and cause of the pain.
CONCLUSION
Improved understanding of pain physiopathology will serve as the basis for future improvements in the delivery of efficacious and reliable treatments, and is likely to rely on novel technological innovations.
Topics: Humans; Nociceptors; Pain; Pain Perception
PubMed: 32525788
DOI: 10.2174/1874467213666200611142438 -
The Journal of Pain Nov 2019Exercise is considered an important component of effective chronic pain management and it is well-established that long-term exercise training provides pain relief. In... (Review)
Review
Exercise is considered an important component of effective chronic pain management and it is well-established that long-term exercise training provides pain relief. In healthy, pain-free populations, a single bout of aerobic or resistance exercise typically leads to exercise-induced hypoalgesia (EIH), a generalized reduction in pain and pain sensitivity that occurs during exercise and for some time afterward. In contrast, EIH is more variable in chronic pain populations and is more frequently impaired; with pain and pain sensitivity decreasing, remaining unchanged or, in some cases, even increasing in response to exercise. Pain exacerbation with exercise may be a major barrier to adherence, precipitating a cycle of physical inactivity that can lead to long-term worsening of both pain and disability. To optimize the therapeutic benefits of exercise, it is important to understand how EIH works, why it may be impaired in some people with chronic pain, and how this should be addressed in clinical practice. In this article, we provide an overview of EIH across different chronic pain conditions. We discuss possible biological mechanisms of EIH and the potential influence of sex and psychosocial factors, both in pain-free adults and, where possible, in individuals with chronic pain. The clinical implications of impaired EIH are discussed and recommendations are made for future research, including further exploration of individual differences in EIH, the relationship between exercise dose and EIH, the efficacy of combined treatments and the use of alternative measures to quantify EIH. PERSPECTIVE: This article provides a contemporary review of the acute effects of exercise on pain and pain sensitivity, including in people with chronic pain conditions. Existing findings are critically reviewed, clinical implications are discussed, and recommendations are offered for future research.
Topics: Chronic Pain; Exercise; Humans; Hyperalgesia; Hypesthesia; Pain Perception; Pain Threshold
PubMed: 30904519
DOI: 10.1016/j.jpain.2019.03.005 -
Neurophysiologie Clinique = Clinical... Oct 2014We here review behavioral, neuroimaging and electrophysiological studies of hypnosis as a state, as well as hypnosis as a tool to modulate brain responses to painful... (Review)
Review
We here review behavioral, neuroimaging and electrophysiological studies of hypnosis as a state, as well as hypnosis as a tool to modulate brain responses to painful stimulations. Studies have shown that hypnotic processes modify internal (self awareness) as well as external (environmental awareness) brain networks. Brain mechanisms underlying the modulation of pain perception under hypnotic conditions involve cortical as well as subcortical areas including anterior cingulate and prefrontal cortices, basal ganglia and thalami. Combined with local anesthesia and conscious sedation in patients undergoing surgery, hypnosis is associated with improved peri- and postoperative comfort of patients and surgeons. Finally, hypnosis can be considered as a useful analogue for simulating conversion and dissociation symptoms in healthy subjects, permitting better characterization of these challenging disorders by producing clinically similar experiences.
Topics: Brain; Humans; Hypnosis; Hysteria; Nerve Net; Pain Perception
PubMed: 25306075
DOI: 10.1016/j.neucli.2013.09.006 -
Neuron Aug 2015Recent neuroimaging studies suggest that the brain adapts with pain, as well as imparts risk for developing chronic pain. Within this context, we revisit the concepts... (Review)
Review
Recent neuroimaging studies suggest that the brain adapts with pain, as well as imparts risk for developing chronic pain. Within this context, we revisit the concepts for nociception, acute and chronic pain, and negative moods relative to behavior selection. We redefine nociception as the mechanism protecting the organism from injury, while acute pain as failure of avoidant behavior, and a mesolimbic threshold process that gates the transformation of nociceptive activity to conscious pain. Adaptations in this threshold process are envisioned to be critical for development of chronic pain. We deconstruct chronic pain into four distinct phases, each with specific mechanisms, and outline current state of knowledge regarding these mechanisms: the limbic brain imparting risk, and the mesolimbic learning processes reorganizing the neocortex into a chronic pain state. Moreover, pain and negative moods are envisioned as a continuum of aversive behavioral learning, which enhance survival by protecting against threats.
Topics: Affect; Animals; Avoidance Learning; Brain; Humans; Nociception; Pain; Pain Perception
PubMed: 26247858
DOI: 10.1016/j.neuron.2015.06.005 -
Nature Neuroscience May 2023A painful episode can lead to a life-long increase in an individual's experience of pain. Fearful anticipation of imminent pain could play a role in this phenomenon, but...
A painful episode can lead to a life-long increase in an individual's experience of pain. Fearful anticipation of imminent pain could play a role in this phenomenon, but the neurobiological underpinnings are unclear because fear can both suppress and enhance pain. Here, we show in mice that long-term associative fear memory stored in neuronal engrams in the prefrontal cortex determines whether a painful episode shapes pain experience later in life. Furthermore, under conditions of inflammatory and neuropathic pain, prefrontal fear engrams expand to encompass neurons representing nociception and tactile sensation, leading to pronounced changes in prefrontal connectivity to fear-relevant brain areas. Conversely, silencing prefrontal fear engrams reverses chronically established hyperalgesia and allodynia. These results reveal that a discrete subset of prefrontal cortex neurons can account for the debilitating comorbidity of fear and chronic pain and show that attenuating the fear memory of pain can alleviate chronic pain itself.
Topics: Mice; Animals; Chronic Pain; Memory, Long-Term; Fear; Brain; Prefrontal Cortex; Hyperalgesia; Pain Perception
PubMed: 37024573
DOI: 10.1038/s41593-023-01291-x -
Neuropharmacology Aug 2020The opioid epidemic has led to a serious examination of the use of opioids for the treatment of pain. Opioid drugs are effective due to the expression of opioid... (Review)
Review
The opioid epidemic has led to a serious examination of the use of opioids for the treatment of pain. Opioid drugs are effective due to the expression of opioid receptors throughout the body. These receptors respond to endogenous opioid peptides that are expressed as polypeptide hormones that are processed by proteolytic cleavage. Endogenous opioids are expressed throughout the peripheral and central nervous system and regulate many different neuronal circuits and functions. One of the key functions of endogenous opioid peptides is to modulate our responses to pain. This review will focus on the descending pain modulatory circuit which consists of the ventrolateral periaqueductal gray (PAG) projections to the rostral ventromedial medulla (RVM). RVM projections modulate incoming nociceptive afferents at the level of the spinal cord. Stimulation within either the PAG or RVM results in analgesia and this circuit has been studied in detail in terms of the actions of exogenous opioids, such as morphine and fentanyl. Further emphasis on understanding the complex regulation of endogenous opioids will help to make rational decisions with regard to the use of opioids for pain. We also include a discussion of the actions of endogenous opioids in the amygdala, an upstream brain structure that has reciprocal connections to the PAG that contribute to the brain's response to pain.
Topics: Amygdala; Animals; Humans; Opioid Peptides; Pain; Pain Management; Pain Perception; Periaqueductal Gray; Receptors, Opioid
PubMed: 32422213
DOI: 10.1016/j.neuropharm.2020.108131 -
Nature Neuroscience Jul 2020General anesthesia (GA) can produce analgesia (loss of pain) independent of inducing loss of consciousness, but the underlying mechanisms remain unclear. We hypothesized...
General anesthesia (GA) can produce analgesia (loss of pain) independent of inducing loss of consciousness, but the underlying mechanisms remain unclear. We hypothesized that GA suppresses pain in part by activating supraspinal analgesic circuits. We discovered a distinct population of GABAergic neurons activated by GA in the mouse central amygdala (CeA neurons). In vivo calcium imaging revealed that different GA drugs activate a shared ensemble of CeA neurons. CeA neurons also possess basal activity that mostly reflects animals' internal state rather than external stimuli. Optogenetic activation of CeA potently suppressed both pain-elicited reflexive and self-recuperating behaviors across sensory modalities and abolished neuropathic pain-induced mechanical (hyper-)sensitivity. Conversely, inhibition of CeA activity exacerbated pain, produced strong aversion and canceled the analgesic effect of low-dose ketamine. CeA neurons have widespread inhibitory projections to many affective pain-processing centers. Our study points to CeA as a potential powerful therapeutic target for alleviating chronic pain.
Topics: Anesthetics, General; Animals; Central Amygdaloid Nucleus; Female; GABAergic Neurons; Male; Mice; Neural Pathways; Pain; Pain Perception
PubMed: 32424286
DOI: 10.1038/s41593-020-0632-8 -
Acta Obstetricia Et Gynecologica... Sep 2021Endometriosis is challenging to treat. It is a painful and chronic inflammatory disorder that impacts up to 10% of women of reproductive age. Despite available surgical...
INTRODUCTION
Endometriosis is challenging to treat. It is a painful and chronic inflammatory disorder that impacts up to 10% of women of reproductive age. Despite available surgical and medical treatment options, recurrence of symptoms is common. Available studies suggest that exercise may have a therapeutic effect on chronic inflammation and thereby on pain perception. This review evaluates whether exercise can decrease pain perception in women with symptomatic endometriosis.
MATERIAL AND METHODS
This systematic review was conducted according to PRISMA by searching databases Medline and Embase to locate randomized controlled trials and observational studies. Risk of bias was investigated using the Cochrane Collaboration Tool for the Evaluation of Randomized Controlled Trials and the ROBINS-I quality assessment scale. Inclusion criteria were women of reproductive age, laparoscopically confirmed diagnosis of endometriosis, and intervention of any type of exercise. All manuscripts were evaluated by two of the authors and when in doubt a third author was consulted. This review was registered in PROSPERO on November 14, 2020 (CRD42020212309).
RESULTS
Six articles fulfilled the inclusion criteria and were included in this systematic review. Concerning exercise, two studies showed significant decrease in pain relief but the remaining studies showed either negative or no impact on pain relief. A meta-analysis could not be conducted because of the considerable heterogeneity among the included studies.
CONCLUSIONS
The present review does not indicate any beneficial effect of exercise on pain in women with endometriosis. There is a need for randomized controlled trials with correct power calculation, well-defined study groups and training programs to be able to answer the question of whether exercise can improve the pain experience in patients with endometriosis.
Topics: Endometriosis; Exercise Therapy; Female; Humans; Pain Perception; Pelvic Pain
PubMed: 33999412
DOI: 10.1111/aogs.14169