The good news is, there’s good news, so read on :-)
One in five Americans suffer from chronic pain and most of them believe they do so because of an injury or breakdown of their tissues. This is called the biomedical model. The biomedical model assumes that injury and pain are the same issue; therefore, an increase in pain is seen as sign of increased tissue injury. Similarly, it is believed that increased tissue injury leads to more pain. This model (called the Cartesian model of pain) is over 350 years old, and is no longer believed to be correct. While there is, in acute pain, often a correlation (although varied, and never absolute) between tissue injury and pain, in chronic pain this correlation falls apart.
One reason for this is that tissue injuries heal, and pain that persists months after an injury can logically not be due to said tissue injury. Sometimes there is not even a distinct injury precipitating the onset of pain, but the onset is gradual. Pain is also highly dependent on our attention, stress, emotions, learned behaviors, beliefs and expectations, including beliefs about what the pain means, whether we feel safe or not, whether we feel empowered or helpless. Psychological factors have actually been found to be more predictive of the development of chronic pain than physical ones.
Modern pain neuroscience has enhanced our understanding of pain
The fundamental thing that modern pain neuroscience research has shown is that chronic chronic pain may not correctly represent the health of the tissue, but may be due to extra-sensitive nerves and modulated by our beliefs and expectations.
You could describe the peripheral nerves leading out to our tissues as wires picking up various signals (touch, temperature, pressure etc) and our brain as the processor that interprets these signals. In a well-functioning system the signals are interpreted correctly. Touch is interpreted as touch, movement as movement etc. But this system can malfunction, and the nervous system can start to misinterpret or over-interpret these signals, so that eg stimulation of receptors in muscles and tendons that should result in a sensation of movement instead results in a sensation of pain.
Pain is created and experienced in the brain
Nociception is the word we give our ability to detect potentially harmful stimuli. It is a protective process that helps us avoid harm by either creating a reflex to pull away from the stimulus, for example a thumb tack you just stepped on, or a sensation that is so unpleasant (read:painful) that it results in behavioral strategies on our part to avoid the stimulus (to look around and step carefully in order to avoid stepping on more thumb tacks). Our “wires” lead the signal of a certain input to the brain, the “central processor”, which then makes an executive decision about whether the stimulus is worthy of our attention, and if so, how much of it. If the brain interprets the signal as a result of a potentially harmful phenomenon, it creates a sensation of pain. Worry, fear, negative beliefs and expectations, previous experiences and many other psychological factors affect the brain's decision-making process.
In some people the alarm system gets stuck at a higher level of sensitivity. With the alarm system extra sensitive and close to the “firing level,” it does not take a lot of movement, stress or activity to activate the alarm system. When this happens, it is natural to think that something must be wrong, even though there is no injury or damage to your body. This is called central sensitization. Central sensitization produces hypersensitivity to pain and other sensations by changing the sensory response elicited by normal inputs. Now even those inputs that usually evoke innocuous sensations such as touch, movement etc may be perceived as pain or other worrysome sensations.
Pain in a person with central sensitization may arise spontaneously without any sensory input such as touch, movement or pressure and it can be elicited by normally harmless stimuli such as gentle touch (this is called allodynia). It is exaggerated and prolonged in response to normally painful stimuli (hyperalgesia), and spreads beyond the original painful area (secondary hyperalgesia).(By the way, these fancy terms are just names for the phenomena we observe, not an additional diagnostic label to be worried about!)
The pain in central sensitization is in other words not proportionate to what is going on in the body.
Sometimes this heightened level of responsiveness of the nervous system is felt only in particular part of the body. Chronic episodic pain is pain that, as the name implies, occurs in episodes, instead of always feeling the same. Pain can be triggered by eg stress, and fear of pain and disability can be a powerful stressor. Individuals with chronic or recurring pain therefore have to work diligently at controlling their thoughts and emotions through education, awareness -building practices such as meditation and other means of keeping levels of stress and catastrophizing thoughts low.
Why do some people develop chronic pain?
There are genetic differences in our pain threshold (how quickly we would characterize a stimulus as painful). Hormonal levels affect our sensitivity to pain. As an example, low level of the sex hormone estrogen, as experienced during certain parts of the menstrual cycle and even more so in menopause increase pain sensitivity. Cold this be part of the reason why middle-aged women are the group most often diagnosed with fibromyalgia? More than anything, our thoughts, beliefs and expectations affect pain.
Sometimes an acute injury leads to an adaptation to pain (think of someone with acute low back pain and how they tend to move) that includes altered movement strategies and a decreased levels of movement that in turn set the stage for chronic pain and malfunction that seems seamlessly connected to the initial injury, but actually is arising from the changes we, consciously and not, made in response to the acute pain. Now the initial injury or muscle spasm is long gone, but the patient has made permanent changes to how they view and use their bodies which create ongoing pain.
Central sensitization represents a more fundamental shift in how the nervous system perceives pain, and all of the reasons for this aren’t well understood just yet. However, we know that anxiety, stress and depression are also present in 30–45% of patients. Other factors that may contribute to symptoms include endocrine dysfunction, psychosocial distress, trauma, and disrupted sleep.
Adversity in childhood can set the stage for central sensitization, and so can traumatic events leading to PTSD.
It is as if though the brain learns that the world is a dangerous place and remains a bit more on high alert, and over-interprets potential signals of danger.
Examples of situations where you’ll find central sensitization are whiplash that persists a long time after the original accident. Fibromyalgia is the prototypic example of central sensitization. Less often, but in a percentage of cases of low back pain, tendon problems, shoulder pain, osteoarthritis, rheumatoid arthritis, pain following cancer treatment, tennis elbow, headaches, shoulder pain, tendonitis of the elbow, knee and ankle central sensitization plays a role. Sometimes central sensitization presents as a heightened sensitivity to pain that seems to move from place to place or be felt in many body regions at the same time. Opiod use can actually lead to an increased pain sensitivity, so called Opioid-induce hyperalgesia.
It may be helpful to think about sensitization in chronic pain as existing on a spectrum, so that you don't either have it or don't have it, but may have more or less of it. All of this also means that when you experience acute pain, you can think and behave in ways that may help prevent chronic pain.
Incorrect beliefs about the nature of pain and a belief that the body is inherently fragile, and subsequent avoidance of movement out of fear of further damaging what the patient believes is an already damaged body, are called Fear Avoidance Beliefs and have been strongly correlated with chronic pain.
If you have had pain for a long time and haven't been getting better, you know or suspect that central sensitization plays a role in the pain you’re feeling, or have been wondering why seemingly innocuous activities often make you hurt so much, or lead you into a spiral of pain, take heart! The reason central sensitization develops in the first place is the so called plasticity of the nervous system, in other words it’s ability to change and learn. If your nerves have learned to become too trigger-happy and your brain has learned to exaggerate signals they can also gradually learn to calm down. Working with a qualified healthcare provider and trusting that the sometimes initially counter-intuitive things you’re learning are true is key. After all, pain in central sensitization feels just the same as any other pain, and it can at first be hard for some patients to understand that it is not a discrete physical injury that is driving the pain, but rather a hypersensitivity of the nerves.
It can also be hard for patients with chronic pain to take in the fact that pain does not go away by waiting for "healing" (of tissues that aren't injured) to take place before increasing movement. That is actually placing the cart before the horse. Even acute pain heals faster and better when appropriate movement is part of the treatment plan!
Here are some key points to consider:
- People with central sensitization and other people that are "sensitive to pain" are not weak. They experience more pain than others and cope with it. However, their pain threshold is low and therefore they experience more and more intense pain than others, from less intense stimuli.
- People with chronic pain need to move towards normal movement gradually. Increasing activity too quickly or engaging in activity that causes too much pain will simply rile up the already sensitive nervous system and cause increased central sensitization. This can lead to a vicious cycle of the patient believing that the are injured, leading to more fear, movement avoidance and, in cases of central sensitization, a heightened level of sensitization.
- People with central sensitization, and indeed most patients with chronic pain, need education more than any other treatment modality in order to understand why they are hurting and to change the trajectory of their situation. Treating muscles and joints alone doesn’t help when the problem is in the nervous system. Passive treatments such as massages and acupuncture will not stop muscles that don't get adequate amounts of movement to stop signaling through pain.
Learn to understand chronic pain. It is important to understand that you are not hurting simply
because of a broken body or injured body part. Understand that pain may not correctly
represent the health of the tissue, but may be due to extra-sensitive nerves or incorrect usage of
Understand that movement, properly introduced and performed, is your friend and will not
injure you. Your body is not fragile! Feeling sore after movement does not mean that you have
been injured or hurt.
Approach movement through graded exposure. Graded exposure means that you are, through
gradually increasing exposure to movement, decreasing the sensitivity of the nervous system
and correcting movement-related pain associations. Your fear of movement, pain and of
"getting hurt" will decrease slowly but surely through gradual, positive experiences .
Find the right provider. Some healthcare professionals may not be quite familiar with current
pain neuroscience. If you are only being treatment with drugs, passive treatment modalities or,
conversely being encouraged to completely disregard pain and work
harder, find a provider that can more appropriately guide you through the
process. You need to find and accept a "Goldilocks-level" of gradually increasing exposure to
Learn to not interpret initial discomfort as a sign that your body is being hurt or injured. Your
body is not fragile. Learn to not focus on sensations of discomfort, and be disciplined abut
redirecting you attention to other sensations and phenomena. What part of your body feels
good? Were you able to make some progress with your exercise program? Did you tolerate
more movement before reaching a familiar level of discomfort? A
brain that fears the sensations it experiences creates much more pain than the
brain of person that is informed and feels safe, not scared. Fear of the pain
itself also increases the intensity of pain.
Focus on progress and ability, not on pain and disability.
Think long-term. No matter how seductive various treatments that only temporarily relieve pain
may be, understand that they are not a way out of chronic pain, and actually
may distract you from the important work at hand. When you are
tired it may feel like you need coffee, and coffee would of course temporarily
help. But the actual problem is not that you haven’t had enough coffee, it is
that you haven’t had enough sleep, and that is the problem you actually need to
solve. If you continue to drink coffee instead of getting some sleep, you’ll
soon be in deep trouble. Remember, the problem doesn’t primarily lie within
the tissues, but in the sensitized nerves, incorrect beliefs and incorrect movement.
You need active work even more than passive treatments.
Knowledge is power. When your brain understands that the
sensations you are noticing are not a sign of danger to your body, it will
actually immediately produce less pain! Remember, the type and amount of pain we
experience is very directly and strongly dependent on our beliefs about the
pain and what it means. Be your own coach and remind yourself of this every day!
A healthy body feels pain sometimes, and gets better by adapting to activity,
not by avoiding it. Waiting for pain to completely go away before returning to
activity is putting the cart before the horse, because resting makes
you weaker, not better adapted for activity. But sudden dramatic increases in
activity may be just as ill advised to the sensitized person. Start low and go
slow is a useful mantra. The body in chronic pain is like a scared cat. You can’t
force it, but you can entice it, and gradually convince it that it is safe to come
out to play.
You are not a passive recipient of pain. It may not feel like it, but pain is a process that takes
place within your own brain, and you have a lot of control over it. By educating yourself,
disciplining your thoughts, finding proper guidance for movement and lifestyle (deep sleep, a
good diet, emotional support, mindfulness and other aspects of a health-supporting lifestyle all
have immense effects on the amount of pain we feel) and trusting your body's inherent strength and capability you can make powerful changes that help you suffer less.
Remember, the way out of chronic pain lies not in avoiding it, but in understanding it and transcending it. You transcend it by understanding its very nature, that it is not warning or guiding you, but deceiving you. It is simply a sign of a nervous system set on high alert, of having ended up in the dead end of avoiding pain instead of confronting it. The opportunity available to us is to slowly but surely reclaim our health and freedom to move and enjoy life.
Do you have questions about how to address or avoid chronic pain? Comment below!