Stress and Pain

Stress and Its’ Role in the Pain Continuum

Stress is the single most important aspect of life, and it can be considered both a good and bad stimulus. Whether you are experiencing the euphoric high experienced after 30 minutes of intense exercises or suffering from “white coat syndrome” where your symptoms are at an all-time high; it is stress that is responsible for how we feel, specifically it is our stress-response.

The human stress-response is a beautiful mechanism that occurs in our bodies with the purpose of maintaining allostasis, dynamic equilibrium. To better understand this concept, consider a seesaw from the good ol’ days. Imagine you have a kid on either side working together to move the seesaw up and down. Each time the kid opposite of you pushes off the ground it causes you to fall towards the ground (stress), but you catch yourself and push off the ground (stress-response). So long as this continues we have allostasis (balance). But what happens if that kid does not push off the ground and you are stuck in the air? Yes stress, but this time the stressor is providing a different input to your system and your stress-response may lead to a cascade of events including loss of balance, high blood pressure, low back pain, and the list can go on and on. So in other words, how a stressor is inputted matters.

Every input our bodies encounter, the stress-response system becomes activated. Whether it be from internal input such as abnormal cellular division (cancer) or an external input that may arrive from a fall or a bout of exercise, the body has to decide how it will respond and produce an output that will attempt to re-establish homeostatsis, a balanced state of a system. This output can be pain.

Pain!!!

Pain tends to get a bad rap because it is an unpleasant experience. However I view pain differently—as a gift. Pain is a useful symptom and is a motivator for behavioral change. Thus, pain lets us know when there is a threatening input. One example would be bumping into a hot stove. It is pain that protects us and causes us to remove our hand from the burner. Some people do not have this luxury; those suffering from pain asymbolia. These folks cannot perceive pain, and it has been documented that they have lost toes without knowledge. Now I do not know about you, but I am thankful I can feel when my body is being stressed by pain so I can change what I am doing.

So How Is Pain Outputted?

I believe knowledge about where and how pain is produced is critically important. First, what is pain? Pain is an emergent output of the brain in response to a nociceptive signal transmitted to the brain. Let me explain this statement further. When we are injured or experiencing nociceptive (danger) signals, our Central Nervous System (CNS) becomes highly active trying to evaluate if our bodies are in a threatening environment. If our brain concludes we are in danger a pain output is produced. However, the context of the stressor must also be considered. You see the pain experience is highly subjective to the brain’s interpretation of the context of your environmental situation. Consider these two examples:

1. You have just sprained an ankle, but your child or loved one is in front of a speeding bus and only you can save them. Your brain evaluates this situation and allows you to rush over and pull them out of the way despite your injured ankle. This is one example of analgesia, the inability to feel pain. To mask the feeling of pain your body is flooded with hormones. This hormone response is defined by your emotional connection to the scenario and results in the release of endogenous morphine. These opiod compounds are neurotransmitters synthesized and released by the pain-producing parts of the brain. This is not by mistake because they like to bind to your pain receptors and alter the brain’s environmental output and blunt the pain response.

2. You herniated a disc in your back 10 years ago when you fell during a hike. Your back has had a low level of residual pain ever since, but has not limited your ability to hike. However, you have not been on the trail you fell on 10 years ago. Now you decide to go on another hike, but this time on the trail you fell on. Your back begins to flare up during the hike. Why? Context. Your body does not forget how you were injured in the past. This is important because research shows that both physical and emotional stressors activate pain pathways in similar manners. This means that by hiking on the trail you fell on you may be experiencing an emotional stressor, thus a pain output is generated. But you may ask, “Isn’t this abnormal because the stressor was not threatening?” No! It is completely normal. You have persistent pain, which reduces nerve sensitivity, making it easier to sound the danger bells (more on this to come). This exemplifies hyperalgesia, an abnormally elevated response to a stressor. Another example of this concept is a papercut. They always hurt so bad!

With these examples in mind we can see there is a continuum of pain that relies on our stress-response (analgesia→hyperalgesia). How our body interprets stress depends on many sensory cues found within our environment and can yield very different responses in different people. Tissue damage(stress) does not equate to pain experienced. This statement is not well understood, but is the fundamental basis for why we need to reconceptualise our views of our pain experiences. To begin to do so let us look at the process of how our body interprets nociceptive signals and outputs pain.

We have danger sensors all over our bodies. When these sensors are activated and reach a critical level, a message via our ascending (towards the brain) fibers is sent to the spinal cord. In response the spinal cord releases excitatory chemicals into the synapse(connection site) with the 2nd order neuron. When these neurons receive enough excitatory input a message is shot up to the brain for further interpretation. The brain then decides if our body is in danger and responds accordingly. In response to a threat our body can and will activate many systems to get us out of danger.

Know Pain For No Pain!

To further reconceptualise we have to appreciate and understand this systemic response. Let us dive deeper into the concept of hyperalgesia. Remember this is a heightened stress-response. Tissue damage causes inflammation and acutely it will promote healing, but when it persists it can cause decreased sensitivity throughout the nervous system. This means that our bodies can more easily produce pain. Think about a home security system that has been set at the highest level. It can be set off by the smallest signal like a fly, yet the response is the same as if it were a burglar, the alarm sounds. When inflammation persists our bodies act like the overactive alarm system and sound the alarms when there is no actual threat. But this does not have to be the case.

Current knowledge shows that focus cannot be solely placed on the tissues with regards to managing pain. Pain is modulated by many factors: somatic, psychological, and even social domains can be involved. These can be understood through a Bio-psycho-social model. This model recognizes the importance of the alarm system sensitivity, fears, attitudes, and beliefs about pain. How we understand and cope with pain affects our pain experience as well as our lives. Knowledge about what pain is is critical in our ability to overcome pain and return to our prior level of function. It is paramount to understand and believe that our hurts are not harmful to our body, but rather an intelligently designed protective mechanism. Pain is normal. Pain is a defender. Pain is a gift. Pain is an emergent output of the brain and knowledge is our output liberator.

References:

Robert Sapolsky: Why Zebra’s Don’t Get Ulcers.

Neuro Orthopaedic Institute: Explain Pain.

Ifast University: Lance Goyke: Homeostasis and Hyperflexibility: Stress, stretching, and what to do with your most difficult clients

#stress #pain #sympathetic