Chiropractor Chandler AZ

The Gate Control Theory of Pain

Pain is defined as “the unpleasant sensory and emotional experiences associated with actual or potential tissue damage.” (Kandel et al., 2013). According to Nobel laureate, Dr. Eric Kandel, “there are no purely painful stimuli… Pain is not the direct expression of a sensory event, but rather the product of elaborate processing by the brain of a variety of neural signals.” (Kandel et al., 2013). In other words, pain has both physiological and somatic origins, both of which are important in its treatment.

In 1965, Ronald Melzack and Patrick Wall published an article in Science magazine that changed the way the medical world conceives of pain. Their Gate Control Theory of Pain proposed that the relative balance of nociceptive and non-nociceptive afferent nerve signals in the dorsal horn influences the perception and transmission of pain (Kandel et al., 2013).

The term, ‘nociceptive,’ refers to small peripheral receptors that respond to painful stimuli by sending afferent signals to different parts of the brain. These “polymodal nociceptors” are activated by stimuli that can potentially damage the tissue within which they are embedded (Mendell, 2014).

Imagine a “gate” in the substantia gelatinosa- a group of cells in the grey area of the spinal dorsal horn that receive direct input from sensory mechano and thermoreceptors. Both large and small afferent fibers pass through this gate before projecting to T cells, that in turn project to the forebrain. Prolonged high intensity stimulation of the small nociceptive fibers creates an imbalance that disrupts inhibition by blocking large fiber input, enabling the pain signals to pass through the gate. (Mendell, 2014)

The brain can also modulate opening and closing of the gate, according to somatic input. Positive mood, distraction and relaxation close the gate, blocking processing of painful stimuli while negative emotions such as fear and anxiety open it. (Katz & Rosenbloom, 2015).

The Gate Control Theory is particularly important in the management of chronic pain, for which there is a large somatic component. Explaining to your patients that they can effectively manage chronic pain via some relatively simple lifestyle changes (see patient PDF) enables them to take back control over their bodies, to be more independent and lead happier, more fulfilling lives.

It is well established that chronic pain triggers and exacerbates, stress, anxiety and depression. As the Gate Control Theory clearly shows us, that relationship is bidirectional (Hunter et al., 2017). Helping your patients to recognize and manage their negative emotions will enable you to more effectively treat the physical symptoms of chronic pain.

References

Hunter, C., Goodie, J., Oordt, M & Dobmeyer, A. Integrated Behavioral Health in Primary Care: Step-by Step Guidance for Assessment and Intervention. Second Edition. pp. 161-174.

Kandell, E., Schwartz, J., Jessell, T., Siegelbaum, S. & Hudspeth, A. (2013). Principles of Neural Science. Fifth Edition. McGraw Hill. pp. 530-545.

Katz, J. & Rosenbloom, B. (2015). The golden anniversary of Melzack and Wall’s gate control theory of pain: Celebrating 50 years of pain research and management. Pain Research and Management. Vol. 20. No. 6. pp. 285-286

Mendell, L. (2014). Constructing and Deconstructing the Gate Theory of Pain. Pain. International Association for the Study of Pain. Vol. 155. No. 2. Pp. 210-216.

How Meditation and Relaxation Can Close the “Pain Gate”

You probably know intuitively that stress, anxiety and depression can increase your pain symptoms. What you may not be aware of is the biological basis for that idea: the Gate Control Theory of Pain.

In the mid-1960s scientists Ronald Melsack and Patrick Wall discovered what they described as a “gate” in the dorsal horn of the spinal cord, through which pain signals travel to the brain. This pain gate opens and closes based on two factors: the proportion of pain signals coming from small pain receptors in the skin, and the brain itself. (Dafny et al., 2020).

Processing inside the brain is what makes us feel pain, based on information received from different types of receptors in the skin that are sensitive to pressure and temperature. Feeling pain is a protective mechanism to prevent us from making injury to the tissue worse.

The rostral ventromedial medulla is a group of cells in the gray matter of the upper spinal cord that control descending pain pathways. Put simply, these cells can inhibit or turn off pain signals. Whereas signals from pain receptors in the skin activate “on” cells that turn on perception of pain, relaxation and meditation do just the opposite, by turning on the “off” cells that block it.

You might be thinking: “How can I relax with chronic pain?”

The answer lies in combining a variety of techniques: remaining physically active, changing negative thought patterns, staying connected to your family and social circle, using relaxation to control anxiety, and adhering to your physician’s recommendations for physical therapy and in some cases, medication (Hunter et al, 2017).

The most important thing to realize is that pain is something you have a certain amount of control over. When you begin to think of yourself as an active participant versus being a passive recipient of your body’s processes, you have taken the first step towards effective pain self-management.

The second very important step starting out is to break the pain cycle that is exacerbated by reacting to physical pain with helplessness, anxiety and frustration. Although self-talk is helpful, it is usually not enough. Following are several relaxation techniques that can help you to refocus your mind on more positive thoughts.

Deep Breathing

Deep breathing, also known as diaphragmatic breathing, is a technique for refocusing your thoughts on internal versus external cues, while at the same time taking more oxygen into your body. As you know, human beings need oxygen to survive. The purpose of our circulation system is to move oxygen from the lungs to various organs and muscles throughout the body.

You can practice deep breathing by lying on a comfortable surface on your back, or if your pain makes this position uncomfortable, in a seated or semi-reclined position. Make sure that the area is quiet and the temperature comfortable.

Place one hand on the top of your sternum, located just below your collarbone. The second hand goes on your diaphragm: a large, dome-shaped muscle located at the top of your abdomen, just below your breasts.

Many individuals (particularly women), use their chest muscles to breathe. This isn’t the most efficient way to get oxygen into the body. To practice breathing with your diaphragm, focus on taking air in through your belly. You should see the hand resting on the diaphragm move up before the hand on your sternum when you initiate a breath. Inhale through the nose and exhale through the mouth, breathing slowly so that you can take in as much oxygen as possible. One trick for taking deeper breaths is to exhale forcefully. Do this by gently pressing down on the diaphragm as you expel air from your body. The more air you expel, the more you can take in.

Now shut your eyes and relax, continuing to breathe using your diaphragm. It may help to count your breaths. You should be breathing very slowly: about 12-14 breaths per minute. By practicing the diaphragmatic breathing technique every day, you will become more proficient at it, and may notice that you begin to use the diaphragm more in your daily activities.

Progressive Muscle Relaxation

Progressive muscle relaxation is a technique for releasing tension in your muscles. When you are in pain, the muscles in the area that is hurting tend to tighten up, and that can make the pain worse. Once again, you can practice this technique lying down, or in a semi-recumbent or seated position.

Beginning with your legs, think about tensing the muscles as you breathe in, and relaxing as you exhale. If you have practiced the diaphragmatic breathing described above, you should be able to breathe deeply and slowly as you do this. After tensing the leg muscles several times, move up to the hands and then the arms, doing the same thing. Follow this with your abdomen, shoulders, head and neck.

What makes this technique effective is that it forces you to focus on one area of the body at a time, and (equally important) take your focus away from the pain. Try to schedule a 15-minute period during the day to practice progressive muscle relaxation, and you should see your pain levels gradually drop.

Guided Imagery

When we talk about seeing things in the mind’s eye, we are referring to the process of using the imagination to create “internal scenery.” By imagining yourself in peaceful surroundings, you can temporarily take your mental focus off of pain.

Once again, it helps to have a system. Begin with a few minutes of diaphragmatic breathing to slow your respiration rate and relax your muscles. Now close your eyes. Think about a place in nature that makes you feel safe and happy. It might be lying on your back in a field of wildflowers, or sitting by a stream watching the water lap over the rocks in the creekbed.

As you know, nothing in nature stands still. That’s the secret sauce behind guided imagery. As you imagine yourself in this natural setting, thoughts about pain and discomfort will gradually drift away. For example, you could imagine that each thought is sitting on a cloud passing overhead, or on leaves that fall from trees surrounding the creekbed, only to be swept downstream.

A second guided imagery technique involves giving your pain shape and form: something small that you can pick up in your hands. As you hold the pain in your hands, move it around and look at every aspect of it. What does the pain look like? Can you imagine this pain looking less threatening? After all, if it is small enough to hold in your hands, you should realize that pain is something you can control.

Now get rid of the pain. Toss it to the side. Remember that you are the decision maker, who determines what role this pain will play in your life.

Some Final Thoughts

While some individuals find these relaxation techniques easy to use, others have more difficulty. You may find that listening to music helps you to get in the best frame of mind for practicing relaxation, that there is a special room in your house that works best, or you might even want to try a mobile app.

Healthline rated the following among its “best for 2020” apps for treating anxiety:

Controlling your pain depends in large part upon the power of positive thought. You feel what you think. Learning to control your emotional responses and you can more effectively manage your pain.

References

Dafny, N. (2020). Pain Modulation and Mechanisms. Neuroscience Online. UTHealth/McGovern Medical School. nba.uth.tmc.edu.

Healthline (2020). Best Anxiety Apps of 2020. Healthline.com

Hunter, C., Goodie, J., Oordt, M. & Dobmeyer, A. (2017). Integrated Behavioral Health in Primary Care: Step-by-Step Guidance for Assessment and Intervention. Second Edition. pp. 161-174.