Pain that lasts longer than three months
Medical conditionChronic pain or chronic pain syndrome is a type of pain that is also known by other titles such as gradual burning pain, electrical pain, throbbing pain, and nauseating pain. This type of pain is sometimes confused with acute pain and can last from three months to several years; various diagnostic manuals such as DSM-5 and ICD-11 have proposed several definitions of chronic pain, but the accepted definition is that it is "pain that lasts longer than the expected period of recovery."
Creating a pain mechanism prevents possible damage to the body, but chronic pain is a pain without biological value (doesn't have a positive effect). This pain has different divisions; cancer, post-traumatic or surgery, musculoskeletal and visceral are the most important of these divisions. Various factors cause the formation of chronic pain, which can be neurogenic (gene-dependent), nociceptive, neuropathic, psychological or unknown. Some diseases such as diabetes (high blood sugar), shingles (some viral diseases), phantom limb pain, hypertension and stroke also play a role in the formation of chronic pain. The most common types of chronic pain are back pain, severe headache, migraine, and facial pain.
Chronic pain can cause very severe psychological and physical effects that sometimes continue until the end of life. Analysis of the grey matter (damage to brain neurons), insomnia and sleep deprivation, metabolic problems, chronic stress, obesity and heart attack are examples of physical disorder; and depression, cognitive disorders, perceived injustice (PI) and neuroticism are examples of mental disorder.
A wide range of treatments are performed for this disease; drug therapy (types of opioid and non-opioid drugs), cognitive behavioral therapy and physical therapy are the most significant of them. Medicines are usually associated with side effects and are prescribed when the effects of pain become severe. Medicines such as aspirin and ibuprofen are used for milder pain and morphine and codeine for severe pain. Other treatment methods, such as behavioral therapy and physiotherapy, are often used as a supplement along with drugs due to their low effectiveness. There is currently no definitive cure for any of these methods, and research continues into a wide variety of new management and therapeutic interventions, such as nerve block and radiation therapy.
Chronic pain is considered a kind of disease; this type of pain has affected the people of the world more than diabetes, cancer and heart diseases. During several epidemiological studies conducted in different countries, wide differences in the prevalence of chronic pain have been reported from 8% to 55.2% in countries; for example, studies evaluate the incidence in Iran and Canada between 10% and 20% and in the United States between 30% and 40%. The results show that an average of 8% to 11.2% of people in different countries have severe chronic pain, and its epidemic is higher in industrialized countries than in other countries. According to the estimates of the American Medical Association, the costs related to this disease in this country are about 560 to 635 billion dollars.
Classification.
The International Association for the Study of Pain (IASP) defines chronic pain as a general pain without biological value that sometimes continues even after the healing of the affected area; a type of pain that cannot be classified as acute pain and lasts longer than expected to heal, or typically, pain that has been experienced on most days or daily for the past six months, is considered chronic pain. According to the DSM-5 index, a complication is "chronic" when the resulting complication (pain, disorder, and illness) lasts for a period of more than six months (this type of classification does not have any prerequisites such as physical or mental injury). The classification of chronic pain is not only limited to pains that arise in the presence of real tissue damage (secondary pains resulting from a primary event); the title "nociplastic pain" or primary pain is related to the pains that occur in the absence of a health-threatening factor, such as disease or damage to the body's somatosensory system, and as a result of permanent nerve stimulation.
The "International Statistical Classification of Diseases", in its 11th edition (ICD-11), proposed a seven-category classification for chronic pain:
Also, the World Health Organization (WHO) states that optional criteria or codes can be used in the classification of chronic pain for each of the seven categories of chronic pain (for example, ""diabetic" neuropathic" pain).
Another classification for chronic pain is "nociceptive" (caused by inflamed or damaged tissue that activates special pain sensors called nociceptors) and "neuropathic" (caused by damage or malfunction of the nervous system). The type of "nociceptive" itself is divided into two parts: "superficial" and "deep"; also, deep pains are divided into two parts: "deep physical" and "deep visceral" pain. "neuropathic" pains are also divided into "peripheral" (source The peripheral nervous system) and "central" (Central nervous system from the brain or spinal cord) are divided. Peripheral neuropathic pain is often described as "burning", "tingling", "electrical", "stabbing", or "pins and needles".
"Superficial pain" is the result of the activation of pain receptors in the skin or superficial tissues; "deep somatic pain" is caused by stimulation of pain receptors in ligaments, tendons, bones, blood vessels, fascia, and muscles. (this type of pain is constant but weak) and "deep visceral pain" is pain that originates from one of the body's organs. Deep pain is often very difficult to localize and occurs in multiple areas of the body when injured or inflamed. In the "deep visceral" type, the feeling of pain exists in a place far from the injury, for this reason it is also called vague pain.
Etiology.
Chronic pain has many pathophysiological and environmental causes and can occur in cases such as neuropathy of the central nervous system, after cerebral hemorrhage, tissue damage such as extensive burns, inflammation, autoimmune disorders such as rheumatoid arthritis, psychological stress such as headache, migraine or abdominal pain (caused by emotional, psychological or behavioral) and mechanical pain caused by tissue wear and tear such as arthritis. In some cases, chronic pain can be caused by genetic factors which interfere with neuronal differentiation, leading to a permanently lowered threshold for pain.
The pathophysiological etiology of chronic pain remains unclear. Many theories of chronic pain fail to clearly explain why the same pathological conditions do not invariably result in chronic pain. Patients' anatomical predisposition to proximal neural compression (in particular of peripheral nerves) may be the answer to this conundrum. Proximal neural lesion at the level of the dorsal root ganglion (DRG) may drive a vicious cycle of chronic pain by causing postural protection of the painful site and consequent neural compression in the same spinal region. Difficulties in diagnosing proximal neural lesion may account for the theoretical perplexity of chronic pain.
Pathophysiology.
The mechanism of continuous activation and transmission of pain messages, leads the body to an activity to relieve pain (a mechanism to prevent damage in the body), this action causes the release of prostaglandin and increase the sensitivity of that part to stimulation; Prostaglandin secretion causes unbearable and chronic pain. Under persistent activation, the transmission of pain signals to the dorsal horn may produce a pain wind-up phenomenon. This triggers changes that lower the threshold for pain signals to be transmitted. In addition, it may cause non-nociceptive nerve fibers to respond to, generate, and transmit pain signals. Researchers believe that the nerve fibers that cause this type of pain are group C nerve fibers; these fibers are not myelinated (have low transmission speed) and cause long-term 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 and theta waves 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 chemokines and cytokines 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.
Management.
Pain management is a branch of medicine that uses an interdisciplinary approach. The combined knowledge of various medical professions and allied health professions is used to ease pain and improve the quality of life of those living with pain. The typical pain management team includes medical practitioners (particularly anesthesiologists), rehabilitation psychologists, physiotherapists, occupational therapists, physician assistants, and nurse practitioners. Acute pain usually resolves with the efforts of one practitioner; however, the management of chronic pain frequently requires the coordinated efforts of a treatment team. Complete, longterm remission of many types of chronic pain is rare.
Chronic pain may originate in the body, or in the brain or spinal cord. It is often difficult to treat. Epidemiological studies have found that 8–11.2% of people in various countries have chronic widespread pain. Various non-opioid medicines are initially recommended to treat chronic pain, depending on whether the pain is due to tissue damage or is neuropathic. Psychological treatments including cognitive behavioral therapy and acceptance and commitment therapy may be effective for improving quality of life in those with chronic 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.
Nonopioids.
Initially recommended efforts are non-opioid based therapies. Non-opioid treatment of chronic pain with pharmaceutical medicines might include acetaminophen (paracetamol) or NSAIDs.
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. 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.
Interventional pain management may be appropriate, including techniques such as trigger point injections, neurolytic blocks, and radiotherapy. While there is no high quality evidence to support ultrasound, it has been found to have a small effect on improving function in non-specific chronic low back pain.
Psychological treatments, including cognitive behavioral therapy and acceptance and commitment therapy can be helpful for improving quality of life and reducing pain interference. Brief mindfulness-based treatment approaches have been used, but they are not yet recommended as a first-line treatment. The effectiveness of mindfulness-based pain management (MBPM) has been supported by a range of studies.
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.
While exercise has been offered as a method to lessen chronic pain and there is some evidence of benefit, this evidence is tentative. For people living with chronic pain, exercise results in few side effects.
Opioids.
In those who have not benefited from other measures and have no history of either mental illness or substance use disorder treatment with opioids may be tried. If significant benefit