The Stress-Pain Cycle

What is the stress-pain cycle? Pain is one of the biggest driving forces that causes patients to seek physical therapy intervention. Whether it is from a traumatic injury, overuse, degeneration, post-surgery, or other factors, the vast majority of cases our physical therapists treat is musculoskeletal pain.

But what about the effect of STRESS on pain? No doubt, we are living through stressful times. Perhaps now more than ever, understanding the connection between stress, our response to it, and the symptoms of chronic pain is critical. In this special three part Stress & Pain series, we aim to explore the antagonistic relationship between pain and stress, its unwanted effects, and how to break the cycle.

Understanding Stress

First, let’s make a distinction between pain-related stress, and non-pain related stress: Pain-related stress refers to a person’s fear and perception of their physical pain. Studies show that if a person exaggerates their response to pain-related stress, it can heighten their physical pain and impede/lengthen recovery. Non-pain stressors include work, family, financial, and other personal sources of stress. If amplified, these too can increase the pain and inhibit healing.

The Role of Cortisol

It is important to understand the basics of what happens when there is a stress response. When we are presented with a stressful situation, our brain signals a release of specific hormones that help us manage, cope with, and/or avoid the hazardous stimulant. Cortisol, produced in the kidney, is one of these hormones. It helps us maintain blood glucose levels that regulate our energy and support proper organ function. Cortisol is also strong anti-inflammatory agent. When we are presented with a physical or psychological stressor, our cortisol levels increase. Therefore, cortisol is effective for helping us to manage short-term strain.

However, cortisol can be dangerous when released over a prolonged period of time due to chronic stress. Lengthy exposures to stress or repeated instances of stress can lead to cortisol dysregulation. This can happen if the stressor is physiological or psychological.

One animal study found that a decreased corticosterone (cortisol equivalent in rats) response occurred after eight days to two weeks of exposure to a stressful stimulus. When the cortisol response malfunctions in humans, there can be an unregulated inflammatory response, which can lead to various dangerous outcomes including free radical damage, cell death, and tissue degeneration. Stress-induced inflammation is connected to various disorders, including chronic low back pain, TMJ pain, chronic pelvic pain, fibromyalgia, osteoporosis, and rheumatoid arthritis, among others. Specific symptoms of stress-induced inflammation include tissue degeneration, low blood pressure, fatigue, depression, and pain. Therefore, we see this cycle:

The Stress-Pain Cycle

Prolonged stress –> cortisol dysregulation –> adverse symptoms and potential disorders –> pain (which itself is also a stressor).

Understanding Pain

The International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.” Several key factors that further define is that 1) pain is personal experience; 2) pain is different than just the activation of our sensory neurons, or nociception; 3) we learn the concept of pain through human development; 4) an individual’s pain should be respected; 5) verbal expression of pain is not the only indication that it exists; 6) pain can be harmful to one’s well-being, despite that it is also adaptive.

Acute Pain

Our sensory systems protect our bodies and help to identify, locate, and recognize tissue damage via the perception of pain. This concept explains acute pain, where an alarming signal is sent from damaged tissues in the body and transmitted through specific neurologic pathways to the brain. When we feel acute pain, it provides clues as to what disease or injury is occurring, which leads to a treatment to alleviate the source of pain.

Chronic Pain

More recently, pain has been viewed as a multi-dimensional entity that includes sensory, cognitive, and emotional aspects. This is certainly true of chronic pain. The simple definition of chronic pain is that it is pain that has persisted for more than three months. Both cognitive and emotional qualities can affect our perception of pain and how it is processed in our brains. Studies have shown that our brains’ pain pathways are altered by our attentional state, positive or negative emotions, and other factors that are directly unrelated to the pain itself.

Long-term Affects

Interestingly, studies have also found that prolonged pain experiences can lead to structural changes in the brain. This sort of plasticity, which describes changes to our nervous system, can become maladaptive in certain cases of chronic pain, and pain no longer is a guardian of our bodies’ health, but instead can turn into a disease itself. Studies of chronic low back pain, fibromyalgia, irritable bowel syndrome, and chronic headache pain found decreased gray matter in certain areas within the brain.

In turn, it is certainly concerning to consider how this affects the rest of our functional, bodily systems. These diminutive changes to our brain tissues have detrimental interactions on our sensory, immune, and cognitive processes. These abnormal changes likely also describe how an acute pain can become chronic; that is, a temporary pain that changes into a permanent problem.

It is clear that dealing with a chronic pain state is physically and cognitively stressful, and could easily turn into a self-perpetuating cycle! Knowing how to recognize and manage our pains is of the utmost importance, especially since most of us are juggling much more in life than just trying to take care of our bodies! If we are privileged enough to be able to impart some control and management over our pains and stresses, we must try.

Managing Stress & Pain

It is clear that the body and brain connection is extremely complex and multifaceted. There are genetic, psychological, physical, personality, and environmental factors that can all affect how we perceive pain and how that pain manifests. Self-regulation of pain describes the capability of one to adapt to the pain condition by maintaining control, guiding, or changing one’s reactions and behaviors. This can allow for successful management of pain.

Medication Management vs. Physical Therapy

Oftentimes, patients are prescribed analgesics and antidepressants to treat pain. However, when a contributing source of the pain is affected by or coming from the brain, these medications have been proven to have limited efficacy with only short-term effects.

In physical therapy, our focus is primarily on the physical contributors to pain, versus the non-pain related stressors in the pain experience. However, it is important for us as PTs to identify our patients who may be struggling with stress management. Then, we can further educate and empower our patients to address potential issues beyond just their physical ailments. Of course, this may entail a multidisciplinary approach, with potential referrals to psychotherapists and other mental health professionals. What other factors might also be vital for a physical therapist and patient to consider when treating the stress/pain cycle?

Developing Sleep Hygiene

We all know sleep is absolutely critical to survival, but stress can cause sleep problems. Researchers have found that sleep deprivation can directly increase pain sensitivity. One study found that just one night of total sleep deprivation in healthy humans impaired descending neural pathways, causing increased excitability of spinal receptors, thus elevating sensory sensitivities. Now think of how chronic sleep deprivation could have an effect on a person over time, especially one that is already dealing with a painful condition. Another study found that even reduced sleep duration of less than 6 hours led to decreased pain thresholds immediately the following day. Promoting healthy sleep habits and developing better “sleep hygiene” can help to break this stress/pain cycle. One study found that a sleep hygiene treatment had profound positive effects on patients with fibromyalgia as an alternative treatment option.

The Role of Exercise

Exercise is another factor that must be considered that is hugely beneficial to us physiologically. A meta-analysis found that aerobic exercise can lead to decreased pain perception as well as an acute improvement in mood. In fact, there is a correlation between exercise and less damaging effects of stress both physically and mentally; as well as evidence that exercise can increase one’s resilience to stress. Of course, as physical therapists, we promote home exercise programs to directly “fix” the problem(s) our patients come to us with. However, addressing a patient’s regular exercise routine, especially one that is aerobic in nature, can have additional benefits in relieving their pain and stress.

Relaxation Techniques

Lastly, relaxation techniques can also have positive influences on reducing the pain and stress cycle for a variety of individuals. These techniques help to elicit the body’s “relaxation response”, which is the opposite of the stress response. As we relax, our blood pressure, breathing rate, and heart rate all decrease. Such relaxation techniques include breathing exercises (diaphragmatic breathing, breath classes); guided imagery or visualization (picturing scenes, objects, ideas that help you feel calm); biofeedback-assisted relaxation (using an electronic device to help you monitor your heart and breath rate, blood pressure, stress levels) ; progressive muscular relaxation (consciously tensing muscles and then relaxing them); and autogenic training (using mental exercises to focus on relaxing). Studies have found this to be effective in treating post-surgical pain, low back pain, headache pain. The effect however is low, and would be worth further research. However, being aware of these relaxation techniques can still be helpful for anyone dealing with stress.

Hopefully this three-part series on how the stress/pain cycle works can empower all of us- as patients, practitioners, and humans- to be aware of how our mental health may be affecting our physical condition. Let’s not forget to work on sleeping better, exercising more consistently, and making conscientious efforts to relax. Certainly, all of us have been under duress for a while and having more tools in our toolbox to keep our bodies healthy and our minds happy will serve us well into this new year!

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