Chronic pain: an update on burden, best practices, and new advances

Fibromyalgia is characterized by chronic widespread pain, fatigue, sleep disturbances and functional symptoms. The etiopathogenesis, diagnostic criteria and classification criteria of fibromyalgia are still debated and, consequently, so are the strategies for treating this condition. Fibromyalgia is the third most frequent musculoskeletal condition, and its prevalence increases with age. However, although diagnosis has improved with the evolution of more accurate diagnostic criteria, a considerable proportion of physicians still fail to recognize the syndrome. Many factors contribute to the development of fibromyalgia in a unique manner: genetic predisposition, personal experiences, emotional-cognitive factors, the mind-body relationship and a biopsychological ability to cope with stress. The multiple components of the pathogenesis and maintenance of the condition necessitate a multi-modal treatment approach. Individually tailored treatment is an important consideration, with the increasing recognition that different fibromyalgia subgroups exist with different clinical characteristics. Consequently, although an evidence-based approach to fibromyalgia management is always desirable, the approach of physicians is inevitably empirical, and must have the aim of creating a strong alliance with the patient and formulating shared, realistic treatment goals.

Fibromyalgia: an update on clinical characteristics, aetiopathogenesis and treatment

Introduction: Given our improved understanding of the role of central sensitization (CS) in many patients with chronic pain, it seems rational to account for CS during treatment. Areas covered: First, the treatment rationale based on the complex mechanisms underlying CS in patients having chronic pain is presented. Second, emphasis is given to explaining the concept of CS when providing treatment, as well as why patients and clinicians should focus on long-term rather than short-term treatment effects. Third, possible pharmacological and non-pharmacological treatment options are discussed. Expert opinion: Centrally acting drugs such as tricyclic compounds, serotonin-norepinephrine reuptake inhibitors, and α2δ ligands each target mechanisms that are often dysfunctional in patients having chronic pain and CS, but decades of clinical practice and clinical trials have not resulted in satisfactory outcomes. This comes as no surprise; CS comprises complex psycho-neuro-immunological interactions, while each of the tested drugs targets one or two of those mechanisms from a purely biomedical viewpoint. Clinicians willing to take CS into account should design an individually tailored multimodal treatment plan comprising pain neuroscience education, cognition-targeted exercise therapy, sleep management, stress management, and/or dietary intervention.

Treatment of central sensitization in patients with chronic pain: time for change?

Opioid use disorders (OUDs) are diseases of the brain with behavioral, psychological, neurobiological, and medical manifestations. Vulnerability to OUDs can be affected by factors such as genetic background, environment, stress, and prolonged exposure to μ-opioid agonists for analgesia. Two standard-of-care maintenance medications, methadone and buprenorphine-naloxone, have a long-term positive influence on health of persons with opioid addiction. Buprenorphine and another medication, naltrexone, have also been approved for administration as monthly depot injections. However, neither medication is used as widely as needed, due largely to stigma, insufficient medical education or training, inadequate resources, and inadequate access to treatment. Ongoing directions in the field include (i) personalized approaches leveraging genetic factors for prediction of OUD vulnerability and prognosis, or for targeted pharmacotherapy, and (ii) development of novel analgesic medicines with new neurobiological targets with reduced abuse potential, reduced toxicity, and improved effectiveness, especially for chronic pain states other than cancer pain.

Current status of opioid addiction treatment and related preclinical research

OBJECTIVES: Improvements in pain management might be achieved by matching treatment to underlying mechanisms for pain persistence Many authors argue for a mechanism-based classification of pain, but the field is challenged by the wide variation in the proposed terminology, definitions, and typical characteristics This study aimed to (1) systematically review mechanism-based classifications of pain experienced in the musculoskeletal system; (2) synthesize and thematically analyze classifications, using the International Association for the Study of Pain categories of nociceptive, neuropathic, and nociplastic as an initial foundation; and (3) identify convergence and divergence between categories, terminology, and descriptions of each mechanism-based pain classification MATERIALS AND METHODS: Databases were searched for papers that discussed a mechanism-based classification of pain experienced in the musculoskeletal system Terminology, definitions, underlying neurobiology/pathophysiology, aggravating/easing factors/response to treatment, and pain characteristics were extracted and synthesized on the basis of thematic analysis RESULTS: From 224 papers, 174 terms referred to pain mechanisms categories Data synthesis agreed with the broad classification on the basis of ongoing nociceptive input, neuropathic mechanisms, and nociplastic mechanisms (eg, central sensitization) "Mixed," "other," and the disputed categories of "sympathetic" and "psychogenic" pain were also identified Thematic analysis revealed convergence and divergence of opinion on the definitions, underlying neurobiology, and characteristics DISCUSSION: Some pain categories were defined consistently, and despite the extensive efforts to develop global consensus on pain definitions, disagreement still exists on how each could be defined, subdivided, and their characteristic features that could aid differentiation These data form a foundation for reaching consensus on classification

Systematic Review and Synthesis of Mechanism-based Classification Systems for Pain Experienced in the Musculoskeletal System.

Chronic pain is a common public health problem that has a detrimental impact on patient health, quality of life (QoL), and function, and poses a substantial socioeconomic burden. Evidence supports the redefinition of chronic pain as a distinct disease entity, not simply a symptom of injury or illness. Chronic pain conditions are characterized by three types of pain pathophysiology (i.e. nociceptive, neuropathic, and centralized pain/central sensitization) influenced by a cluster of coexisting psychosocial factors. Negative risk/vulnerability factors (e.g. mood or sleep disturbances) and positive resilience/protective factors (e.g. social/interpersonal relationships and active coping) interact with pain neurobiology to determine patients' unique pain experience. Viewing chronic pain through a biopsychosocial lens, instead of a purely biomedical one, clinicians need to adopt a practical integrated management approach. Thorough assessment focuses on the whole patient (not just the pain), including comorbidities, cognitive/emotional/behavioral characteristics, social environment, and QoL/functional impairment. As for other complex chronic illnesses, the treatment plan for chronic pain can be developed based on pain subtype and psychosocial profile, incorporating pharmacotherapy and self-management modalities. Preferred pharmacologic treatment of conditions primarily associated with nociception (e.g. osteoarthritis) includes acetaminophen and non-steroidal anti-inflammatory drugs, whereas preferred pharmacologic treatment of conditions primarily associated with neuropathy or central sensitization (e.g. fibromyalgia) includes tricyclic compounds, serotonin-norepinephrine reuptake inhibitors, and α2δ ligands. Education, exercise, cognitive behavioral therapy, and many other non-pharmacological approaches, alone or combined with pharmacotherapy, have been shown to be effective for any type of pain, although they remain underutilized due to lack of awareness of their benefits and reimbursement obstacles.

Kim D Jones

Papers

Reframing chronic pain as a disease, not a symptom: rationale and implications for pain management.