Chronic Pain

Not all people with chronic pain have a health problem diagnosed by a healthcare provider, but among those who do, the most frequent conditions are low-back pain or osteoarthritis, according to a national survey. Other common diagnoses include rheumatoid arthritis, migraine, carpal tunnel syndrome and fibromyalgia.

Chronic pain may result from an underlying disease or health condition, an injury, medical treatment (such as surgery), inflammation or a problem in the nervous system (in which case it is called “neuropathic pain”); or the cause may be unknown. Pain can affect quality of life and productivity, and it may be accompanied by difficulty in moving around, disturbed sleep, anxiety, depression and other problems.

Females are at greater risk for many pain conditions and often report a higher prevalence of chronic pain than men. Females are also likely to have more pain from certain diseases, such as cancer. In addition, some chronic pain disorders occur only in females while others occur predominantly in males. These include chronic fatigue syndrome, endometriosis, fibromyalgia, interstitial cystitis, vulvodynia and temporomandibular disorders.

Three theories that might explain the differences in pain experience are:

1. A gender-role theory assuming that it is more socially acceptable for females to report pain.
2. An exposure theory suggesting that females are exposed to more pain risk factors.
3. A vulnerability theory proposing that females are more vulnerable to developing certain types of pain, such as musculoskeletal pain.

Of these, the vulnerability theory is best supported by scientific evidence.

Cultural perspectives and identification in a specific racial or ethnic group can influence a patient's report of pain. Initial research also indicates that healthcare providers' expectations of a person's pain can be influenced by race or ethnicity. People of different races/ethnicities often experience different rates of clinically painful conditions. Some research has shown that African Americans, Asians and Hispanics demonstrate lower pain tolerance compared to Caucasians. Stereotypes also have resulted in the undertreatment of racial/ethnic minorities. Some studies suggest that there are disparities in pain management for a variety of conditions and treatment settings. They indicate that African Americans and Hispanics are more likely to have their pain undertreated than Caucasians.

The likelihood of experiencing pain and the type of care one receives differs for children and the very old, compared to young and middle-aged adults.

Pain is the number-one medical complaint of older Americans. Research suggests that more severe pain and pain that interferes with activities increases with age. Evidence also shows that older people are more vulnerable to severe or persistent pain and that the inability to tolerate severe pain also increases with age. Some of the most common causes of pain in older adults include joint pain, post-surgical pain, chronic disease and conditions associated with aging.

Chronic pain becomes more common as people grow older, at least in part because some health problems that can cause pain, such as osteoarthritis, become more common with advancing age. Pain management in the older population differs from that in younger people. For example, older people are much more likely to experience medication-related side effects than younger people.

Pain in children also requires special attention. Identifying the problem and getting a proper diagnosis can be particularly difficult because young children often are not able to describe the degree of pain that they are experiencing. Also, a child's pain is often undertreated for various reasons, one being there are few evidence-based recommendations regarding medication-prescribing practices for children and adolescents.

Although treating pain in children poses challenges to physicians and parents alike, children should never be undertreated. Specific tools and questionnaires for measuring pain in children have been developed that, when combined with feedback from parents, can help physicians select the most effective treatments.

Differences in our genes highlight how differently we experience pain. Scientists believe that genetic variations can determine your risk for developing chronic pain, how sensitive you are to painful stimuli, whether certain therapies will reduce your pain, and how you experience acute and/or chronic pain. Many genes contribute to pain perception, and mutations in one or more pain-related genes account for some of the variability of pain experiences.

Some people born insensate to pain (meaning they cannot feel pain) have a mutation in part of a gene that plays a role in electrical activity of nociceptors and other types of neurons. A different mutation in that same gene can cause a severe and disabling pain condition. Scientists have identified many genes involved in pain by screening large numbers of people with pain conditions for shared gene mutations. While genes play a role in determining your sensitivity to pain, they only account for a portion of this variability. Ultimately, your sensitivity to pain is governed by a complex interaction of genes, cognitions, mood, our environment and early life experiences.

The link between the nervous and immune systems is important. Cytokines, a group of proteins found in the nervous system, are also part of the immune system—the body's shield for fighting off disease and responding to injury. Cytokines can trigger pain by promoting inflammation, even in the absence of injury or damage. After a trauma, cytokine levels rise in the brain and spinal cord and at the site of the injury. Improvements in our understanding of the precise role of cytokines in producing pain may lead to new classes of drugs that can block the action of these substances to produce analgesia.

Pain can be classified as acute or chronic, and the two kinds differ greatly.

1. Acute pain usually results from a specific injury, disease and/or inflammation. It generally comes on suddenly, for example, after physical trauma or surgery, and can be accompanied by anxiety or emotional distress. Normally, acute pain is a protective response to tissue damage resulting from injury, disease, overuse, or environmental stressors. The cause of acute pain can be diagnosed and treated. The pain is self-limiting, meaning it is confined to a given period of time and severity. Acute pain, however, can become chronic.
2. Chronic pain is a medical disease that can be made worse by environmental and psychological factors. Chronic pain persists over a long period and can be challenging to manage. People with chronic pain often suffer from more than one painful condition. They also have an increased risk for developing problems with physical functioning, cognition and emotional reactions. There may be common mechanisms that put some people at higher risk for developing multiple pain disorders. It is not known whether these disorders share a common cause.

There is no way to objectively measure pain. Only the person experiencing pain can describe how much pain they feel. After learning about your pain history and other medical concerns, your healthcare provider may conduct physical exams and clinical assessments, and order diagnostic tests and imaging to assess pain intensity and diagnose or rule out any conditions.

Healthcare providers have many approaches and technologies to help identify the cause of pain, including:

• A musculoskeletal and neurological examination in which the physician tests movement, reflexes, sensation, balance and coordination.
• Laboratory tests (e.g., blood, urine and cerebrospinal fluid) can help the physician diagnose infection, cancer, nutritional problems, endocrine abnormalities and other conditions that may cause pain.
• Electrodiagnostic procedures including electromyography (EMG), nerve conduction studies, evoked potential (EP) studies and quantitative sensory testing measure the electrical activity of muscles and nerves. They help physicians evaluate muscle symptoms that may result from a disease or an injury to the body's nerves or muscles. EMG tests muscle activity and identifies which muscles or nerves are affected by weakness or pain. Nerve conduction studies (usually performed along with an EMG) record how nerves are functioning. EP studies measure electrical activity in the brain in response to sight, sound or touch stimulation. Quantitative sensory testing can establish thresholds for sensory perception that can then be compared to normal values. These tests are used to detect abnormalities in sensory function and nerve disorders.
• Imaging, especially magnetic resonance imaging (MRI), provides a look inside the body's structures and tissues, such as the brain and spinal cord. MRI uses magnetic fields and radio waves to differentiate between healthy and diseased tissue. Ultrasound imaging uses high-frequency sound waves to obtain images inside the body.
• Nerve blocks not only treat but can also help to diagnose the cause of pain. A person's response to a nerve block may help the provider to determine what is causing the pain or where it is coming from, since pain signals can spread throughout the body.
• Psychological assessments often are performed when assessing chronic pain. There is a high prevalence of depression, anxiety and emotional distress associated with chronic pain (and vice versa), and often the diagnoses can be hard to separate. A provider may ask a patient to complete psychological questionnaires or ask how the person is feeling emotionally.
• X-rays produce pictures of the body's structures, such as bones and joints. Bone scans can help diagnose and track infection, fractures or other bone disorders.

The goal of pain management is to improve function—enabling you to work, attend school and participate in daily activities. The many treatment options will vary depending on the type of pain, its duration and your access to care.

The best way to prevent, assess and treat chronic pain is the biopsychosocial treatment model. This model allows you, your healthcare providers and your caregivers to view pain as a dynamic interaction among and within the biological, psychological and social factors that are unique to you. It provides the best foundation for tailoring the most comprehensive pain management program for you.

Interdisciplinary treatment—which involves team members from different healthcare specialties working collaboratively to set goals, make decisions, and share resources and responsibilities—is based on the biopsychological model that is important when assisting chronic pain sufferers.

For the most part, the medications, procedures, interventions and therapies listed below have been shown in clinical trials to help relieve or manage pain associated with a specific condition(s), but none have been proven fully effective in relieving all types of pain. Discuss with your healthcare provider which treatment, or combination of treatments, will be most effective for you and your pain condition. It is important to remember that, while not all pain is curable, all pain can be treated. Common treatments include:

• Acupuncture involves the application of needles to precise points on the body to relieve pain. It is part of a category of healing called traditional Chinese medicine (TCM). Evidence of the effectiveness of acupuncture for pain relief is conflicting and clinical studies to investigate its benefits are ongoing.
• Analgesic refers to the class of drugs that includes most “painkillers.” This includes classes of non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen and naproxen, as well as acetaminophen and opioids (which have a narcotic effect and can induce sedation and pain relief). Nonprescription or over-the-counter (OTC) pain relievers are generally used for mild to moderate pain. Prescription opioid pain relievers, sold through a pharmacy under the direction of a physician, are used for moderate to severe acute pain and are usually prescribed for short periods of time.
• Anticonvulsants are used to treat seizure disorders because they dampen abnormally fast electrical impulses. They also are prescribed by physicians to treat various pain conditions, particularly neuropathic pain.
• Antidepressants are often used to treat chronic pain and are particularly used to help manage musculoskeletal pain, neuropathic pain and headache-related pain.
• Anti-inflammatory diets (nutrition) are another approach to chronic pain management. Research suggests that some people with chronic pain can benefit from eating anti-inflammatory foods to help reduce their level of pain with limited negative side effects.
• Beta-blockers are medications that inhibit one arm of the sympathetic nervous system and adrenal “fight-or-flight” hormones. Propranolol and timolol are used to prevent migraine headaches.
• Biofeedback is used to treat many common pain problems, most notably headache and back pain. Biofeedback enables individuals to learn how to change physiological activity for the purpose of improving health and performance. The biofeedback machine provides rapid and accurate feedback that helps people become aware of, follow and gain control over certain bodily functions, including muscle tension, heart rate, breathing rate and skin temperature.
• Botox (botulinum toxin) is a U.S. Food and Drug Administration (FDA)–approved treatment for chronic migraines (those that last for or occur for 15 or more days a month). Botox is injected around pain fibers that are involved in headaches. Botox enters the nerve endings and blocks the release of chemicals involved in pain transmission.
• Calcitonin gene-related peptide (CGRP) monoclonal antibodies are a class of FDA-approved medications to help prevent frequent migraines. Some of the new medications include erenumab (Aimovig), fremanezumab (Ajovy) and galcanezumab (Emgality).
• Chiropractic care may ease back pain, neck pain, headaches and musculoskeletal conditions. It involves “hands-on” therapy designed to adjust the relationship between the body's structure (mainly the spine) and its functioning. Chiropractic spinal manipulation includes the adjustment and manipulation of the joints and adjacent tissues. Such care may also involve therapeutic and rehabilitative exercises. A review of numerous clinical trials to assess the effectiveness of spinal manipulations concludes that there is only low-quality evidence of their benefit for acute and subacute low back pain. For chronic back pain however, there is evidence of small to moderate treatment relief.
• Cognitive-behavioral therapy (CBT) is a well-established treatment for pain that involves helping an individual improve coping skills—pacing day-to-day activities, addressing negative thoughts and emotions that can amplify pain, and learning relaxation methods to help prepare for and cope with pain and changes in the nervous system. It is used for chronic pain, postoperative pain, cancer pain, and with transitions from acute to chronic pain.
• Counseling can give an individual pain sufferer much needed support, whether it comes from family, group, or individual counseling. Support groups can provide an important supplement to drug or surgical treatment. Psychological treatment also can help people learn how to better handle physiological changes produced by pain.
• Electrical stimulation, including implanted electric nerve stimulation, and deep brain or spinal cord stimulation, is the modern-day version of age-old practices in which the nerves or muscles are stimulated by heat or massage. The following techniques require specialized equipment and trained personnel:
  • TENS (transcutaneous electrical stimulation) uses tiny electrical pulses, delivered through the skin to nerve fibers, to cause changes in muscles, such as numbness or contractions. This in turn produces temporary pain relief. TENS can activate subsets of peripheral nerve fibers that can block pain transmission at the spinal cord level.
  • Peripheral nerve stimulation uses electrodes placed surgically or percutaneously (injected through the skin) on a peripheral nerve. The individual is then able to send an electrical current as needed to the affected nerve, using a controllable electrical generator.
  • Spinal cord stimulation uses electrodes surgically or percutaneously inserted between the spine's protective covering (the dura) and the spinal column. The individual can send a pulse of electricity to the spinal cord using an implanted electrical pulse generator that resembles a cardiac pacemaker.
  • Deep brain stimulation is considered a more extreme treatment and involves surgical stimulation of the brain, usually the thalamus or motor cortex. It treats chronic pain in cases that do not respond or have stopped responding to less invasive or conservative treatments.
• Exercise may also be a part of the pain treatment regime for most people. A physician or physical therapist can recommend an appropriate routine. Participation in some form of exercise, physical activity and stretching may help individuals with pain better manage their symptoms, handle daily activities, and maintain flexibility and muscle strength. Exercise, sleep, and relaxation can all help reduce stress, thereby helping to alleviate pain. Supervised exercise has been proven to help many people with low back pain.
• Hypnosis, in general, is used to control physical function or response—that is, the amount of pain an individual can withstand. How hypnosis works is not fully understood, and there is limited research suggesting its effectiveness. Some believe that hypnosis enables individuals to improve their ability to concentrate and/or relax.
• Injections are sometimes used to deliver pain relief medication locally, including:
  • Facet injections target the facet joints (small stabilizing joints in the spine between and behind vertebrae). A person may get pain relief from the local anesthetic and may notice longer lasting relief starting two to five days after injection.
  • Steroid injections work by decreasing inflammation and reducing the activity of the immune system. Injecting steroids into one or two local areas allows doctors to directly deliver a high dose of medication.
  • Sacroiliac joint injection is used to diagnose the source of a person's pain, as well as to provide therapeutic pain relief associated with sacroiliac joint dysfunction. The injection provides pain relief by reducing inflammation within the joint.
  • Trigger point injections involve injecting a small amount of local anesthetic, sometimes with a steroid medication, directly into a painful trigger point (a specific site on the muscles that causes pain when pressed during an exam).
• Low-power lasers have been used by some healthcare providers as a treatment for pain. This low intensity light therapy (not thermal) triggers biochemical changes within cells and may have an effect on pain, inflammation and tissue repair, but this method is considered experimental.
• Marijuana (cannabis) continues to remain highly controversial as a medical treatment to manage pain. Scientific studies are underway to test the safety and usefulness of cannabis for treating different medical conditions. Although marijuana has not been approved for any medical use at the federal level, several states and the District of Columbia permit the use of medical marijuana as a treatment.
• Marinol is an FDA-approved medication with the active ingredient dronabinol, a synthetic form of tetrahydrocannabinol (THC) used to treat chemotherapy-induced nausea and vomiting. Initial research has found that Marinol was no more effective than placebo for post-surgical and nerve-related pain, and only slightly more effective than placebo for chronic non-cancer pain.
• Muscle relaxants are used to relax and reduce tension in muscles. Muscle relaxants are not a class of drugs, which means that they do not all have the same chemical structure or work the same way in the brain. The term “muscle relaxers” describes a group of drugs that act as central nervous system depressants and have sedative properties for musculoskeletal pain.
• Anxiolytics include medications in the class of benzodiazepines, used to decrease central nervous system activity. These drugs can act as muscle relaxants and are sometimes used to manage anxiety.
• >Nerve blocks use drugs, chemical agents or surgical techniques to interrupt the relay of pain messages between specific areas of the body and the brain. Nerve blocks may involve local anesthesia, regional anesthesia or analgesia, or surgery, and are routinely used for traditional dental procedures. Nerve blocks can be used to prevent or even diagnose pain and may involve injection of local anesthetics to numb the nerve and/or steroids to reduce inflammation.
  • Neurolytic blocks employ injection of chemical agents such as alcohol, phenol or glycerol, or the use of radiofrequency energy, to kill nerves responsible for transmitting nociceptive signals. Neurolytic blocks are most often used to treat cancer pain or pain in the cranial nerves.
  • Sympathectomy, also known as sympathetic blockade, typically involves injecting local anesthetic next to the sympathetic nervous system (involved with regulating heart rate, breathing, blood pressure and response to stressful or dangerous situations). The procedure is often performed to treat neuropathic pain of a limb (e.g., complex regional pain syndrome) as well as vascular disease pain and other conditions.
  • Surgical blocks are performed on cranial, peripheral or sympathetic nerves. They are most often used to relieve cancer pain and extreme facial pain, such as that experienced with trigeminal neuralgia. There are several types of surgical nerve blocks and they are not without problems and complications. Nerve blocks can cause muscle paralysis and, in many cases, result in partial numbness. For that reason, the procedure should be reserved for a select group of individuals and should only be performed by skilled surgeons. Types of surgical nerve blocks include:
    • Spinal dorsal rhizotomy, in which the surgeon cuts the root or rootlets of one or more of the nerves radiating from the spinal cord.
    • Cranial rhizotomy and trigeminal rhizotomy, performed as a treatment for extreme facial or cancer pain.
• Physical therapy and rehabilitation may help to decrease pain and improve mobility by increasing function, controlling pain and aiding recovery. Individuals may engage in a number of physical therapy treatments simultaneously. A few of the most common forms in addition to the above are:
  • Traction to decrease pain and improve mobility in the spine.
  • Joint mobilization, such as when a physical therapist passively moves the joints of the body in specific directions to help decrease pain and improve mobility.
  • Heat to increase circulation to the injured tissues, relax the muscles and provide pain relief. Ice helps decrease pain and control inflammation.
  • Kinesiology taping uses a flexible tape to support body parts and muscles to reduce bruising/swelling and provide pain relief.
• Placebos are defined as substances without any therapeutic effect that are typically used as a control factor in clinical studies to determine the effectiveness of a medical treatment. Placebos are inactive substances, such as sugar pills, or harmless procedures such as saline injections, and may be prescribed more for the psychological benefit than for any physiological effect. Placebos, however, do offer some individuals pain relief. Although placebos have no direct effect on the underlying causes of pain, evidence from clinical studies suggests that many respond well to them. This is known as the placebo response, which is defined as the observable or measurable change that can occur after administration of a placebo. One significant component responsible for the effect of placebo is the degree to which people expect the treatment to work. Placebos work in part by stimulating the brain's own analgesics.
• Relaxation and mindfulness are ways for people to respond to the physical sensation of pain, which can have a major impact on how the body's nervous system creates and perceives pain. An individual's automatic reactions to pain, often unconsciously, can amplify the pain-generating activity of the nervous system. Relaxation strategies (e.g., imagery, progressive muscle relaxation, autogenic relaxation) and mindfulness techniques (exercises that help the individual observe physical, cognitive, and emotional reactions and make skillful choices to relieve pain) are evidence-based practices that help shift the nervous system back toward a non-pain state.
• Rest, Ice, Compression, and Elevation (R.I.C.E.) are four components prescribed by many orthopedists, coaches, trainers, nurses and other professionals for temporary muscle or joint injuries, such as sprains or strains.
• Radiofrequency ablation (RFA) uses an electrical current produced by a radio wave to heat up a small area of nerve tissue to decrease pain signals from that specific area. The degree of pain relief can vary depending on the cause and location of the pain. Some individuals can experience pain relief for up to six months to a year.
• Serotonergic agonists—triptans like sumatriptan, naratriptan and zolmitriptan—are used specifically for acute migraine headaches because they block pain pathways in the brain. Taken as pills, shots or nasal sprays, they can relieve many symptoms of migraine.
• Surgery may be recommended for some people with pain that significantly affects their daily functioning. Surgery may be considered when less invasive treatments have not been helpful. However, surgical procedures are not always successful and may not be appropriate for everyone.
• Topical pain creams and gels are sprayed on or rubbed into the skin over painful muscles or joints. Although they are all designed to relieve pain, they have different ingredients. Topical pain creams and gels (e.g., compounded pain creams to treat specific pain) are sometimes prescribed by a physician, while others can be bought over the counter. There is limited evidence about the effectiveness of such creams. Below are the most common ingredients in products available without a prescription.
  • Capsaicin (pronounced cap-SAY-sin) is a chemical found in chili peppers and is also a primary ingredient in prescription or over-the-counter pain-relieving creams as a treatment for several pain conditions, including shingles. This topical cream may be helpful for deep pain. It works by reducing the amount of substance P—a compound thought to be involved in the synaptic transmission of pain and other nerve impulses—that is found in nerve endings and interferes with the transmission of pain signals to the brain. Individuals can become desensitized to the compound, however, perhaps because of long-term capsaicin-induced damage to nerve tissue. Some people cannot tolerate the burning sensation they experience when using capsaicin cream.
  • Counterirritants include ingredients such as menthol, methylsalycylate (oil of evergreen) and camphor. They are called counterirritants because they create a burning or cooling sensation that distracts the person from the pain.
  • Salicylates are the same ingredients that give aspirin its pain-relieving quality and are found in some creams. When absorbed into the skin, they may help with pain, particularly in joints close to the skin, such as fingers, knees and elbows.

Pain is the number-one medical complaint of older Americans. Research suggests that more severe pain and pain that interferes with activities increases with age. Evidence also shows that older people are more vulnerable to severe or persistent pain and that the inability to tolerate severe pain also increases with age. Some of the most common causes of pain in older adults include joint pain, post-surgical pain, chronic disease and conditions associated with aging.

Pain management in the older population differs from that in younger people. For example, older people are much more likely to experience medication-related side effects than younger people.

Pain in children also requires special attention. Identifying the problem and getting a proper diagnosis can be particularly difficult because young children often are not able to describe the degree of pain that they are experiencing. Also, a child's pain is often undertreated for various reasons, one being there are few evidence-based recommendations regarding medication-prescribing practices for children and adolescents.

Although treating pain in children poses challenges to physicians and parents alike, children should never be undertreated. Specific tools and questionnaires for measuring pain in children have been developed that, when combined with feedback from parents, can help physicians select the most effective treatments.

Consider participating in a clinical trial so clinicians and scientists can learn more about migraine and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.