Chronic pain is pain that persists or recurs for longer than 3 months. It is also described as burning, electrical, throbbing, or nauseating pain. This type of pain contrasts with acute pain, which is associated with a specific cause, typically resolves when the cause is treated, and decreases over time. Chronic pain can last for years. Persistent pain often serves no apparent useful purpose.
The most common types of chronic pain include back pain, severe headache, migraine, and facial pain. Chronic pain can lead to severe psychological and physical effects that may persist for a lifetime. Physical complications can include damage to brain Neuron (grey matter loss), insomnia and sleep deprivation, metabolic disorders, chronic stress, obesity, and heart attack. Mental health consequences may include depression and neurocognitive disorders.
A wide range of treatments are used for chronic pain; drug therapy including opioid and non-opioid drugs, cognitive behavioral therapy and physical therapy are the most common interventions. Medications such as aspirin and ibuprofen are used for mild pain whereas morphine and codeine are prescribed for severe pain. Non-pharmacological treatments, such as behavioral therapy and Physical therapy, are often used as complementary approaches due to their limited effectiveness when used alone. There is currently no definitive cure for chronic pain, and research continues into new management and therapeutic options, such as nerve block and radiation therapy.
An average of 8% to 11.2% of people in different countries experience severe chronic pain, with higher incidence in industrialized countries. Epidemiology studies show prevalence in countries varying from 8% to 55.2% (for example 30-40% in the US and 10-20% in Iran and Canada). Chronic pain affects more people than diabetes, cancer, and heart disease. According to the estimates of the American Medical Association, the costs related to chronic pain in the US are about US$560-635b.
Subcategories of MG30 are:
Primary chronic pain (MG30.0) has subcategories:
Specific pain syndromes can be placed in these categories.
The pathophysiological etiology of chronic pain remains unclear. Many theories of chronic pain
These changes in neural structure can be explained by neuroplasticity. When there is chronic pain, the somatotopic arrangement of the body (the distribution view of nerve cells) is abnormally changed due to continuous stimulation and can cause allodynia or hyperalgesia. In chronic pain, this process is difficult to reverse or stop once established. EEG of people with chronic pain showed that brain activity and synaptic plasticity change as a result of pain, and specifically, the relative activity of beta wave increases and Alpha wave and decrease.
Inefficient management of dopamine secretion in the brain can act as a common mechanism between chronic pain, insomnia and major depressive disorder and cause its unpleasant side effects. Astrocytes, microglia and satellite glial cells also lose their effective function in chronic pain. Increasing the activity of microglia, changing microglia networks, and increasing the production of and by microglia may exacerbate chronic pain. It has also been observed that astrocytes lose their ability to regulate the excitability of neurons and increase the spontaneous activity of neurons in pain circuits.
Chronic pain is associated with fibromyalgia.
Chronic pain can significantly reduce individuals' quality of life, productivity, and wages, worsen existing health issues, and provoke the onset of new conditions like major depression, , and substance use disorders.
Many of the often-used medications for chronic pain carry risks for side effects and complications. For example, chronic use of opioids is associated with decreased life expectancy and increased mortality of patients relative to non-users. Acetaminophen, a frequently used drug in chronic pain management, can cause hepatotoxicity when taken in excess of four grams per day, and even therapeutic doses administered to pain patients with chronic liver disease may cause hepatotoxicity. Long-term risks and side effects of opioids, another class of analgesic, include constipation, drug tolerance and Drug dependence, nausea, indigestion, arrhythmia (e.g., QT prolongation during methadone treatment), endocrine gland disruptions promoting amenorrhea, erectile dysfunction, and gynecomastia, and fatigue. A major public health and clinical concern in and since the 2010s has been opioid overdose, especially in the context of an opioid epidemic in the United States.
As of 2011, drug treatments for chronic non-cancer pain reduced pain by 30%, although effectiveness varied widely by modality, diagnosis, and population studied. This reduction in pain can significantly improve patients' performance and quality of life. However, the general and long-term prognosis of chronic pain shows decreased function and quality of life. Also, this disease causes many complications and increases the possibility of death of patients and suffering from other chronic diseases and obesity. Similarly, patients with chronic pain who require opioids often develop drug tolerance over time, and this increase in the amount of the dose taken to be effective increases the risk of side effects and death.
Mental disorders can amplify pain signals and make symptoms more severe. In addition, comorbid psychiatric disorders, such as major depressive disorder, can significantly delay the diagnosis of pain disorders. Major depressive disorder and generalized anxiety disorder are the most common comorbidities associated with chronic pain. Patients with underlying pain and comorbid mental disorders receive twice as much medication from doctors annually as compared to patients who do not have such co-morbidities. Studies have shown that when coexisting diseases exist along with chronic pain, the treatment and improvement of one of these disorders can be effective in the improvement of the other.
Patients with chronic pain are at higher risk for suicide and . Research has shown approximately 20% of people with suicidal thoughts, and between 5 and 14% of patients with chronic pain commit suicide. Of patients who attempted suicide, 53.6% died of gunshot wounds, and 16.2% died of opioid overdose.
Sleep disturbance, and insomnia due to medication and illness symptoms are often experienced by those with chronic pain.
Severe chronic pain is associated with increased risk of death over a ten-year period, particularly from heart disease and respiratory disease. Several mechanisms have been proposed for this increase, such as an abnormal stress response in the body's endocrine system. Additionally, chronic stress seems to affect risks to heart and lung (cardiovascular) health by increasing how quickly plaque can build up on artery walls (arteriosclerosis). However, further research is needed to clarify the relationship between severe chronic pain, stress and cardiovascular health.
People with chronic pain tend to have higher rates of depression and although the exact connection between the comorbidities is unclear, a 2017 study on neuroplasticity found that "injury sensory pathways of body pains have been shown to share the same brain regions involved in mood management." Chronic pain can contribute to decreased physical activity due to fear of making the pain worse. Pain intensity, pain control, and resilience to pain can be influenced by different levels and types of social support that a person with chronic pain receives, and are also influenced by the person's socioeconomic status.
In a study, Mendelian randomization was used to identify Causality between chronic pain and certain psychiatric, cardiovascular, and inflammatory conditions that were initially thought to be unrelated to pain. It was found that exposure to depression increases the likelihood of reporting pain, but not the other way around. Exposure to coronary diseases increases the risk of developing chronic pain, and vice versa. An increase in body mass index modestly raises the likelihood of experiencing pain, while high blood HDL levels reduce the probability of suffering from chronic pain. Regarding inflammatory traits, exposure to asthma increases the likelihood of experiencing pain, and vice versa.
Chronic pain of different causes has been characterized as a disease that affects brain structure and function. MRI studies have shown abnormal anatomical and functional connectivity, even during rest involving areas related to the processing of pain. Also, persistent pain has been shown to cause grey matter loss, which is reversible once the pain has resolved.
One approach to predicting a person's experience of chronic pain is the biopsychosocial model, according to which an individual's experience of chronic pain may be affected by a complex mixture of their biology, psychology, and their social environment.
Chronic pain may be an important contributor to suicide.
A multimodal treatment approach is essential for better pain control and outcomes, as well as minimizing the need for high-risk treatments such as opioid medications. Managing comorbid depression and anxiety is critical in reducing chronic pain. Patients with chronic pain should be carefully monitored for severe depression and any suicidal thoughts and plans. Periodic referral of the patient to the doctor for physical examination and to check the effectiveness of treatment too is necessary, and the rapid and correct treatment and management of chronic pain can prevent the occurrence of potential negative consequences on the patient's life and increase in healthcare costs.
As of 2024, the patient is encouraged to play a major role in the management of their pain.
Some people with chronic pain may benefit from opioid treatment while others can be harmed by it.
People with non-cancer pain who have not been helped by non-opioid medicines might be recommended to try opioids if there is no history of substance use disorder and no current mental illness.
A 2023 review said that future chronic pain diagnosis and treatment would be more personalized and precision based.
Various other nonopioid medicines can be used, depending on whether the pain is a result of tissue damage or is neuropathic (pain caused by a damaged or dysfunctional nervous system).
There is limited evidence that cancer pain or chronic pain from tissue damage as a result of a conditions (e.g. rheumatoid arthritis) is best treated with opioids.
For neuropathic pain other drugs may be more effective than opioids, such as tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and anticonvulsants.
Some atypical antipsychotics, such as olanzapine, may also be effective, but the evidence to support this is in very early stages. In women with chronic pain, hormonal medications such as oral contraceptive pills ("the pill") might be helpful. When there is no evidence of a single best fit, doctors may need to look for a treatment that works for the individual person.
Nefopam may be used when common alternatives are contraindicated or ineffective, or as an add-on therapy. However it is associated with adverse drug reactions and is toxic in overdose.
Some people with chronic pain benefit from opioid treatment and others do not; some are harmed by the treatment. Possible harms include reduced sex hormone production, hypogonadism, infertility, impaired immune system, falls and fractures in older adults, neonatal abstinence syndrome, heart problems, sleep-disordered breathing, physical dependence, addiction, abuse, and overdose.
It is difficult for doctors to predict who will use opioids just for pain management and who will go on to develop an addiction. It is also challenging for doctors to know which patients ask for opioids because they are living with an opioid addiction. Withholding, interrupting or withdrawing opioid treatment in people who benefit from it can cause harm.
Among older adults psychological interventions can help reduce pain and improve self-efficacy for pain management. Psychological treatments have also been shown to be effective in children and teens with chronic headache or mixed chronic pain conditions.
Implementing dietary changes, which is considered a biological-based alternative medicine practice, has been shown to help improve symptoms of chronic pain over time. Adding supplements to one's diet is a common dietary change when trying to relieve chronic pain, with some of the most studied supplements being: acetyl-L-carnitine, alpha-lipoic acid, and vitamin E. Vitamin E is perhaps the most studied out of the three, with strong evidence that it helps lower neurotoxicity in those with cancer, multiple sclerosis, and cardiovascular diseases.
Hypnosis, including self-hypnosis, has tentative evidence. Hypnosis, specifically, can offer pain relief for most people and may be a safe alternative to pharmaceutical medication. Evidence does not support hypnosis for chronic pain due to a spinal cord injury.
Preliminary studies have found medical marijuana to be beneficial in treating neuropathic pain, but not other kinds of long term pain. , the evidence for its efficacy in treating neuropathic pain or pain associated with rheumatic diseases is not strong for any benefit and further research is needed. For chronic non-cancer pain, a recent study concluded that it is unlikely that are highly effective. However, more rigorous research into cannabis or cannabis-based medicines is needed.
Tai chi has been shown to improve pain, stiffness, and quality of life in chronic conditions such as osteoarthritis, low back pain, and osteoporosis. Acupuncture has also been found to be an effective and safe treatment in reducing pain and improving quality of life in chronic pain including chronic pelvic pain syndrome.
Transcranial magnetic stimulation for reduction of chronic pain is not supported by high quality evidence, and the demonstrated effects are small and short-term.
Spa therapy could potentially improve pain in patients with chronic lower back pain, but more studies are needed to provide stronger evidence of this.
While some studies have investigated the efficacy of St John's Wort or nutmeg for treating neuropathic (nerve) pain, their findings have raised serious concerns about the accuracy of their results.
KT tape has not been shown to be effective in managing chronic non-specific low-back pain.
Myofascial release has been used in some cases of fibromyalgia, chronic low back pain, and tennis elbow but there is not enough evidence to support this as method of treatment.
Some investigators have argued that it is this neuroticism that causes acute pain to turn chronic, but clinical evidence points the other way, to chronic pain causing neuroticism. When long term pain is relieved by therapeutic intervention, scores on the neurotic triad and anxiety fall, often to normal levels.
It has been suggested that catastrophizing might play a role in the experience of pain. Pain catastrophizing is the tendency to describe a pain experience in more exaggerated terms than the average person, to think a great deal more about the pain when it occurs, or to feel more helpless about the experience. People who score highly on measures of catastrophization are likely to rate a pain experience as more intense than those who score low on such measures. It is often reasoned that the tendency to catastrophize causes the person to experience the pain as more intense. One suggestion is that catastrophizing influences pain perception through altering attention and anticipation, and heightening emotional responses to pain. However, at least some aspects of catastrophization may be the product of an intense pain experience, rather than its cause. That is, the more intense the pain feels to the person, the more likely they are to have thoughts about it that fit the definition of catastrophization.
With a large proportion of the global population enduring prolonged periods of social isolation and distress, one study found that people with chronic pain from COVID-19 experienced more empathy towards their suffering during the pandemic.
Management
Overview
Medications
Nonopioids
Opioids
Psychological treatments
Exercise
Other interventions
Alternative medicine
Epidemiology
Psychological aspects
Personality
Comorbidity with trauma
Comorbidity with depression
Effect on cognition
Social and personal impacts
Social support
Racial disparities
Perceptions of injustice
Chronic pain and COVID-19
Relationship with conventional medicine
Effect of chronic pain in the workplace
See also
Notes
Further reading
External links
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