Are you living with chronic pain? (Part 1)
Chronic pain is a complex and distressing problem for an estimated 20% of people worldwide, and this number is increasing year on year. In the United States, annual costs related to health care delivery and lower worker productivity due to chronic pain is estimated to be around $600 billion dollars, far greater than heart disease ($309 billion), cancer ($243 billion), and diabetes ($188 billion). For many, the source is often unseen and persistent, for example, a slipped disc or trapped nerve. It can be mild or severe, it can be continuous as in osteoarthritis, or it can be intermittent as in migraines. However, in around one-third of cases, no physical cause for the pain can be found, or pain persists long after the injury has healed. In many cases, chronic pain is a disorder in itself rather than being the symptom of a disease process, and over time it may affect what we can do, our ability to work, our sleep patterns, and our overall quality of life.
What’s the difference between acute and chronic pain?
Acute pain is generally intense and short-lived, like an alarm telling us something is wrong, which stops once the underlying injury is identified and treated. If we cut or burn our finger, it causes tissue damage, which is registered by microscopic pain receptors known as nociceptors. When activated, the pain receptors send electrical signals via nerve fibres to an area in the neck called the dorsal horn, then up to the brain by means of chemical messengers called neurotransmitters. The end result is that we feel a sensation of pain in our finger.
Most of the time pain goes away after an injury heals, but if it persists beyond normal tissue healing time, which is generally three months, it can become chronic pain. Sometimes pain becomes chronic because the underlying problem doesn’t heal. For instance, arthritis causes inflammation and damage to the joints, and it may hurt as long as the inflammation lasts. Unfortunately, chronic pain may also occur despite healing and with no obvious injury to tissues. The problem may be due to damage to the peripheral nervous system (the nerves leaving the spinal cord) or central nervous system (the brain and spinal cord), which can give rise to pain, numbness, hyper-sensitivity, weakness and spasms, and can be very difficult to treat.
Are some people at higher risk of chronic pain than others?
There are several physical, psychological, social, and emotional risk factors associated with chronic pain, which can affect its duration and intensity. Historically, these have been classified as ‘modifiable’ and ‘non-modifiable’ and are specific to the individual;
Socio-economic
According to several population studies, the prevalence of chronic pain is inversely related to socio-economic factors. Those living in deprived neighbourhoods, with low incomes and low levels of education and employment, are not only more likely to experience chronic pain than people from more affluent areas, but are also more likely to experience more severe pain and a greater level of pain-related disability. This relationship, however, may be bidirectional because people with chronic pain may be less likely to be in work, and more likely to be dependent on state benefits and social housing because of their pain. Find more information here.
Mental health
Chronic pain is linked with depression, and depression is linked with chronic pain. A large population study demonstrated that patients who had consulted their general practitioner (GP) for ‘nerves, anxiety, tension, or depression’ had a higher risk of consulting about chronic pain than those who had not consulted their GP in this way (52.2% vs 38.0%). Because of the bidirectional relationship between chronic pain and mental health conditions, implementing strategies to improve mental health can also improve chronic pain. See the full report here.
Adverse childhood experiences
People who have experienced physical or emotional trauma as a child, such as a serious illness or the death of a parent, have a higher risk of chronic pain in their adult lives. Early stress in life can alter the function of the hypothalamic-pituitary-adrenal axis, affecting the stress response. A study of young adults with chronic pain found that over 80% reported at least one adverse childhood experience (ACE) in their lifetime. The most common ACE was having family members with mental health illnesses, and the more ACE’s, the greater the level of psychological distress and widespread chronic pain. See the full report here.
Genes
The relationship between chronic pain and genes is complex. There are known to be at least 150 genes associated with chronic pain in humans, and this number is ever-expanding, but so far, research has failed to identify any single genetic variant that contributes substantially to the risk of developing chronic pain. Whilst there is evidence of chronic pain clusters in family groups, there are also ‘maternal’ effects to consider. It is more likely that a combination of genes act at many levels to shape the experience of chronic pain, influencing emotional, behavioural, and biological processes. Find more information here.
Life-style
Pain can also lead to compensatory behaviours like overeating, smoking, drug, and alcohol use, which can independently or in combination, exacerbate symptoms of chronic pain. Find more information here and here.
Weight management: A large-scale survey with over 1 million people in the USA demonstrated a linear increment of chronic pain cases as Body Mass Index (BMI) increased. Relative to normal-weight people, overweight people reported 20% greater rates of recurring pain, and the rates go up to 68% for people with class I obesity, 136% for people with class II obesity, and 254% for people with morbid obesity. See the full report here.
Smoking: People with chronic pain are more likely to smoke than those with no pain. Smoking is not only harmful to general health, but also to the musculoskeletal system because of an increased risk of bone thinning and fractures, decreased muscle mass, and tendon degeneration. Smokers are reported to have a lower pain threshold, and experience higher pain intensity scores, at a higher number of painful sites than non-smokers and former smokers. Find more information here.
Substance abuse: Opioid addiction and prescription drug abuse is a major public health concern in the United States, and chronic pain may be a contributing factor. Drugs and alcohol are commonly used by people to ‘self-medicate’ for chronic pain. However, regular use can result in them gradually developing a resistance to the analgesic effect, which can lead to a cycle of escalating drug and alcohol dependence. Find more information here.
Inactivity: Physical inactivity may be an important risk factor in the development of chronic pain. Patients who adopt passive coping strategies, such as ‘resting and taking medications’, were found to use three times the amount of healthcare appointments and have double the level of disability from pain in comparison with those who adopt active strategies such as exercise. Several reviews have concluded that exercise and physical activity have positive effects on chronic pain management, and exercise programmes are increasingly being offered by healthcare practitioners, for a variety of chronic pain conditions. Find more information here.
Insomnia: Sleep disorders have been shown to affect nearly half of people reporting chronic pain, with a quarter of chronic pain patients suffering from clinical insomnia. The association is bidirectional, with chronic pain causing poor sleep, and poor sleep increasing the intensity and duration of chronic pain. Find more information here.
Stress: The number one obstacle to pain control is stress. Pain increases when patients are tense and stressed, leading to feelings of fear and helplessness. Relaxation exercises and mindfulness techniques can help build resilience.
Standard medical treatments to manage chronic pain
Management of any type of chronic pain includes a combination of drug and non-drug therapies. Despite advances in medical technology, some pain may involve so many factors that it may not be possible to find the precise cause with X-rays, scans or laboratory tests. However, not knowing the cause of the pain doesn’t mean it doesn’t exist, or that the problems it creates aren’t real. Pain is personal. There is no standard instrument that enables a clinician to measure pain in an objective manner. No two people experience it in the same way, and while there isn't a cure for chronic pain, there are a variety of treatments;
Nonsurgical procedures
Epidural steroid injection: A procedure that can help relieve neck, arm, back, and leg pain caused by inflammation of the spinal nerves due to spinal stenosis or disc herniation. The injection includes both a corticosteroid and an anaesthetic numbing agent, which are delivered into the epidural space of the spine.
Nerve block injection: Also called a pain receptor block injection, this is an injection of anaesthetic on or near a nerve/pain receptor, that can temporarily block the joint or nerve pain, and is used as a diagnostic test to determine the source of the pain. The effects of a nerve/pain receptor block tend to be temporary, but if the block is successful, then a radiofrequency ablation may be recommended.
Radiofrequency ablation: Also called a rhizotomy, this is a minimally invasive procedure that burns or ablates the nerve fibres to reduce or stop the transmission of pain signals to the brain.
Lumbar sympathetic nerve block: An injection of a local anaesthetic and in some cases a corticosteroid, that is delivered into the sympathetic nerves; a cluster of nerve cell bodies along the front side of the spine.
Medications
Acetaminophen (US) / Paracetamol (UK): Usually recommended as a first-line treatment to manage mild to moderate pain.
Nonsteroidal anti-inflammatory drugs (NSAIDs) e.g. Aspirin, Ibuprofen, Naproxen, Diclofenac: Commonly used for arthritis and pain related to muscle sprains, strains, back and neck injuries. They decrease inflammation but are not usually effective against neuropathic pain.
COX-2 inhibitors e.g. Celecoxib: Developed to reduce common side effects associated with traditional NSAIDs, which block COX-1 and COX-2 enzymes, and can cause side effects such as stomach pain and bleeding, because COX-1 helps protect the lining of the stomach. However, COX-2 inhibitors only block COX-2, allowing COX-1 to function normally.
Tricyclic antidepressants e.g. Amitriptyline, Nortriptyline, Clomipramine, Doxepin
Serotonin and norepinephrine reuptake inhibitors (SNRIs) e.g. Duloxetine, Venlafaxine: Antidepressants work by increasing the amount of serotonin made by the brain. Although not specifically intended to treat chronic pain, they’ve been found to be an effective treatment for many chronic pain conditions, particularly neuropathic pain and fibromyalgia.
Anti-seizure medications e.g. Gabapentin, Pregabalin, Carbamazepine, Topiramate, Clonazepam: Also found to relieve chronic pain, these anti-seizure medications are widely used for the treatment of neuropathic pain.
Opioids e.g. Codeine, Oxycodone, Tramadol: Cousins of the drugs derived from opium, such as heroin and morphine. Although they deliver very effective pain relief, they should only be used for chronic pain as a last resort because of the high risk of addiction over the longer term.
Physical therapy
Exercise: People with chronic pain face a dilemma; activity may increase pain, especially at first, but a lack of activity is likely to lead to long-term problems such as poor fitness, increased weight, stiff joints, and muscle weakness. This is particularly true for people who have joint pain associated with arthritis. These problems can then, in turn, cause an increase in pain and lead to other health problems. For any of us, getting started can be difficult. We all ache when we’ve not exercised for a long time. This is a sign that the body is rebuilding muscles and tendons, not a sign of damage. But for people with chronic pain, these aches and pains can be more severe, so they should always speak to their doctor first. A referral to a physiotherapist can help patients learn safe and effective exercises to improve general fitness, and also increase the strength or movement of the muscles or joints associated with their pain.
Heat and ice packs: Ice calms inflammation. Heat warms up the muscles so that they move more easily. Both can help with pain.
Graded Motor Imagery (GMI): A chronic pain treatment that uses our brain’s own plasticity and neural connections to treat our chronic pain. The therapy uses techniques such as visualizing movement without actually moving, using mirrors to trick our brain into thinking that we’re moving a weaker or painful body part when we’re actually moving a stronger body part, and using left-right discrimination exercises to recalibrate crucial parts of our brain that help in pain recovery. GMI helps us regain confidence in physical strength and re-learn motor control, while reconfiguring how we respond to pain.
Sensory re-education: When we suffer a serious injury or illness, chronic pain can occur when the nervous system, overwhelmed by constant, severe pain signals, goes haywire and continues to sense pain even after the injury has healed. Sensory re-education for chronic pain can help desensitize our nervous system to these pain signals so that they’re no longer overwhelming. The re-education protocol usually uses light stimuli on both the unaffected and affected areas so that the brain can begin to compare sensations between the two, and gradually decrease sensitivity in the affected area.
Transcutaneous electrical nerve stimulation (TENS): A TENS machine aims to block, or partially block, pain signals as they pass through the spinal cord on their way to the brain. It does this by passing a mild electrical current through the skin via sticky pads. The sensation of vibration produced by the TENS machine makes it more difficult for nerves in the spine to pass pain messages up to the brain. It is a similar, although more reliable way of reducing pain by ‘rubbing it better’.
Surgical procedures
Surgery is considered only when all nonsurgical and medical treatments have been explored, because surgery involves cutting or interrupting the nerves that carry the pain signals, and there is a risk of a loss of sensation in the affected area;
Spinal cord stimulation: A small device, similar to a pacemaker, is implanted under the skin and transmits mild electrical pulses to the nerve fibres of the spinal cord. Spinal cord stimulation therapy masks pain signals before they reach the brain, and results in a tingling sensation instead of pain.
Intrathecal pain pumps: A small pump is placed under the skin of the abdomen, which delivers pain medication through a catheter directly to the area around the spinal cord. Because medication is delivered straight to the site of the pain, symptoms can be controlled with a much smaller dose of medication than required when taken orally, so the risk of side-effects is reduced.
Psychotherapy
The experience of chronic pain isn’t just about treating the underlying physiological cause, it’s also about managing the thoughts, feelings and behaviours that accompany it. Psychologists are experts in helping people cope with the emotional aspects of pain and will develop an individually tailored treatment plan. This may involve teaching relaxation techniques, changing old beliefs about pain, building new coping skills, and addressing any anxiety, depression or insomnia that accompanies the pain.
What about complementary and alternative medicines?
Complementary and alternative medicines (CAM) offer a broad range of therapies that address the mind-body dynamics of chronic pain, and my next blog will look at a selection that clinical trials have concluded are the most effective. In the meantime, if you are considering making any changes to your treatment, please be sure to discuss them with your doctor first.
Thank you for reading this blog post. If you have any thoughts to share, or ideas for future posts, please do let me know. I would love to hear from you.