A “Guest Post” by Angel Young, Student Physical Therapist
Since the 17th century, humans have understood pain to be a message from the body that something has been damaged or is not working as it should. We believe that there is a physical problem in the area where the pain is felt, and that the greater the pain, the more damage has been done. This makes sense because it is consistent with our experience of pain. If we bump our knee against the coffee table, we feel pain in our knee. If we bump our knee hard it hurts a lot, but if we bump it lightly, the pain is less. You may be surprised to learn that the latest research shows that pain is more far complicated than this.
Only in the last few decades has our understanding of pain evolved. While our traditional understanding of pain works well to explain acute (recent onset) pain, chronic (ongoing) pain can behave very differently. Thanks to the complexity and creativity of our brains, our nervous systems can exaggerate or distort pain signals, causing us to perceive that damage is occurring where it is not. Chronic pain can become its own animal, far removed from what is actually going on with our tissues. Our perception of pain may not be giving us accurate information about what is going on with our bodies. Pain may be felt in areas where there is no actual tissue damage. For example, one feel pain with direct contact at the elbow, but the actual pain problem can be elsewhere – enmeshed in one’s central nervous system.
The term central sensitization is used to describe a condition that is the hallmark of chronic pain. In central sensitization, the nervous system stays on high alert and can cause the brain to perceive harmless stimuli as dangerous and therefore painful. For example, normal changes in temperature, movement, or light pressure can be perceived by an overactive nervous system as highly painful, despite there being no actual danger or damage to the underlying body part. Because of the role of central sensitization, chronic pain can be incredibly difficult to treat. In these situations, applying treatment to the area where pain is perceived is insufficient to affect the sensitivity of the more global neurological system. It is common for people suffering from chronic pain to undergo test after test and treatment after treatment, chasing a perceived injury that really does not have any clear structural presence and thus does not respond.
People with central sensitization tend to have high rates of stress, anxiety, and depression. While we do not entirely understand why this is, we do know that the relationship between pain and stress can cause a vicious, self-enforcing cycle that can culminate in a lot of misery. There are many reasons for this cycle. One reason is that chronic pain can cause people to engage less in physical activity. They are unable to enjoy the benefits of exercise, including stimulating the body’s natural healing process, reducing stress, and calming the nervous system. In addition, fear of pain may prevent us from working, socializing, and engaging in activities that we enjoy. This has the compounded effect of creating more stress, anxiety, and depression, which can in turn cause our nervous system to generate even more pain signals.
Does this concept of central sensitization mean that chronic pain is all in your head? Yes and no. Ultimately, all pain is in our heads, since all sensations arriving from our body tissues are ultimately interpreted as either dangerous or safe by our brains. Regardless of whether or not there is a connection to specific tissue damage, the pain that is felt is very real and must be addressed. However, in addition to addressing the original structural problem and movement impairments that may have resulted from an original injury, in chronic pain conditions the nervous system as a whole must also be calmed down and gradually taught to be less reactive to what it perceives as potential threats.
What does the new pain science tell us about recovering from chronic pain?
- Central sensitization must be addressed. Physical therapists are on the front line of researching and developing new solutions for dealing with chronic pain that address central sensitization. Some of these interventions include graded exercise, manual therapy techniques, graded motor imagery, and even mirror techniques.
- The earlier that acute pain is treated, the better. Acute injuries are easier to manage and take less recovery time than chronic injuries. Once an injury becomes chronic, there may be the added complication of dealing with the effects of central sensitization.
- Don’t be afraid to move. As an old physical therapy adage goes, “Motion is Lotion.” The body is designed to move. Movement can stimulate nutrition delivery and, therefore, healing, especially in areas of poor blood flow such as in cartilage. Physical therapists can prescribe appropriate types and levels of exercise to encourage healing, strengthen muscles for joint support, and minimize pain.
- Movement impairments must be addressed. Chronic pain often begins as micro-trauma – repeated day-to-day wear and tear of the body due to improper body mechanics or musculoskeletal imbalances. Because the initial pain in these situations is slight, people often wait until the pain is much worse or a more serious injury occurs before addressing the underlying problem. Your physical therapist should be able to properly identify and correct movement impairments to prevent micro-trauma and injury.
- A holistic approach to pain treatment is necessary – sleep, stress reduction, and nutrition are all important for healing. We all know that pain can cause lack of sleep. But studies also show that the opposite can be true – that lack of sleep can increase stress, impede healing, and perpetuate chronic pain. Stress can also exacerbate chronic pain by heightening the activity of the nervous system.
- Medical Imaging isn’t everything, especially with chronic back pain. MRI imaging has been shown to have a very low correlation with low back pain. Seeing a disc bulge or nerve root compression on an MRI may have the effect of validating and creating an expectation for the pain that you already feel. But it is important to note that many of us have bulging discs or nerve compression, yet have no symptoms. In fact, one recent study shows that more than 35% of adults without back pain have imaging showing disc problems. The take home message here is that imaging may not completely explain the pain that you feel.
- Don’t bottle it all up. Chronic pain has been shown to correlate with stress, anxiety, depression, and trauma. Consider working with counselors or other mental health professionals to address these issues when they occur. Managing this type of symptom can go a long way towards resolving chronic pain symptoms.
For more information about the current science about pain, here are a couple of resources:
Understanding Pain in Less than 5 Minutes
Central Sensitization in Chronic Pain
Please also ask your physical therapist if you have questions about managing pain.