Chronic pain is problem experienced by major individuals. In America, chronic pain affects more individuals than cancer, diabetes, and coronary heart disease combined! Pain is a complex issue and is often misunderstood. This blog post will cover some of the latest research on what we know about chronic pain.
Normally, pain occurs to alert you of a threat and protect you from danger. The threat can be actual danger or the potential of danger. For example, if you tear a ligament in your ankle, it hurts. This is to alert you to the damaged tissue and to take care of it until it heals. Your body then goes through the staging of healing to rebuild the ligament. First there is inflammation, then scar tissue formation, and finally tissue remodeling. Given enough time, the ligament is healed and the pain stops.
However, sometimes this process doesn’t work like it is supposed to. Sometimes the pain persists long after the tissues have healed. This is called chronic pain, which is typically defined as pain that has lasted for over three months. The most common types of chronic back in order are: (1) low back pain; (2) headache; (3) neck pain; and (4) facial pain (The American Academy of Pain Medicine).
To understand chronic pain, let’s go over a little neuroscience first. Tissues (such as muscles, ligaments, and tendons) contain receptors that sense movements, chemicals, and temperature. When these receptors are triggered, they send an electrical message from the tissue to the spinal cord. Once at the spinal cord, the message is transferred to the spinal cord, which is then carried to the brain for processing. Once the message is at the brain, the brain needs to interpret the message and plan an appropriate reaction.
While there are no “pain receptors” per se, we do have nociceptors, which are sensory receptors that relay messages from the tissues to the brain. If the message is perceived as a threat by the brain, the brain will create pain to protect you (and your tissues!). The brain can also ignore the message if it is not important (for example, do you notice that your socks are touching your feet all day? Probably not).
In chronic pain, the nervous system begins to adapt as more and more danger messages are sent from the tissues to the brain. The nociceptors connecting the tissues and the brain begin to become more sensitive to the chemicals used to transmit the danger message, by increasing the rate of production or the ratio of nociceptors. This results in a lower threshold to activate the nociceptors, causing things that used to hurt to hurt more often, called hyperalgesia. Nerves that do not normally send danger messages can also start to trigger danger signals, which causes things which didn’t hurt before to start hurting (this is called allodynia).
The brain also adapts to the increase in danger signals. The brain connects multiple areas of your brain with each painful experience forming what is called a neurotag matrix. When you go through a similar experience, the brain can trigger the neurotag matrix and recreate the experience to protect you. For example, think about if you were in a car accident. You may have a neurotag matrix that includes the type of car you were in and where the accident was. When you have something that reminds you of the car accident, such as walking by the place you were in the accident, you may shudder or experience pain. This is a result of activation of the neurotag matrix. As the danger signals are triggered more frequently, the brain creates more receptors allowing for the neurotag to be more easily activated.
The brain can also blur the area of the brain responsible for the sensory information of that part of the body, a process known as smudging. Think of this as a blurry picture of that part of the body. The pain may become more vague and diffuse. So now instead of just your big toe hurting, your whole foot now begins to hurt. Remember that you brain is trying to protect you and your tissues from danger.
The good news is that the brain is constantly rewiring and creating new connections, a process called neuroplasticity. This means that while the brain can change due to pain, it can also be reversed to get rid of the pain.
Usually your tissues are as healed as they are going to be once chronic pain has set in. In chronic pain, the way your nervous system is processing the danger signals has been altered, causing prolonged pain. In a way, your brain has been duped into thinking that you and your tissues are still in danger when they aren’t. This isn’t to say that the pain you experience isn’t real, it is real. The difference is the problematic area has changed from the damaged tissue (muscle, ligament, or tendon) to a sensitized nervous system (nerves and brain).
Dealing with chronic pain can be difficult and confusing. Many individuals look for a structural cause for their persistent pain on an X-ray or MRI, which typically reveals little besides some natural aging. Chronic pain is a complex issue. Biological, psychological, and social factors can all contribute to the development and persistence of chronic pain. A structured approach is often helpful in dealing with chronic pain. Knowing that pain is a protective mechanism and that its presence does not necessarily indicate damage to a tissue will aid in the road to recovery. Graded exposure to exercises can also help beat chronic pain (in fact, this is one of the most supported methods for chronic pain!).
The road to recovery may not be easy, but it is possible.
The video below is a great animation explaining chronic pain