How Do We Sense Pain?

In my 38 years as a Clinical Social Worker in the mental health profession I worked with many people who experienced physical pain. Some had acute pain and others chronic pain. Pain as a result of accidents or injury. Pain due to illnesses or medical conditions. Overall, the pain these people experienced resulted in emotional consequences that led them to seek mental health treatment.

For transparency sake, let me mention that I too have experienced physical pain in my life. In fact, I still experience pain on a daily basis (chronic pain). With this increased awareness, I have always been very interested in trying to help people deal emotionally with the pain they feel physically.

Although there is an abundance of research and related materials available regarding this subject, I’d like to discuss three topics which I’ve found to be most helpful to people in counseling.

This article is the first in a three part series titled When You or Your Loved One is in Pain:

1. How Do We Sense Pain?
2. Pain Versus Suffering
3. Mental Health Interventions to Reduce Physical Pain

Definitions of Pain

Charlie Brown, however, is only one source of information regarding definitions of pain! Let’s look at another:

Pain is “a more or less localized sensation of discomfort, distress or agony, resulting from the stimulation of specialized nerve endings.”

Dorland’s Medical Dictionary

How do we sense pain? Pain is a subjective experience, a phenomenon felt by every person differently. It’s difficult to describe pain in a one-size-fits-all way. We’ve developed pain scales to measure the quality and quantity of our pain. But the problem with this is that each person’s pain tolerance is different and we perceive the feeling of pain based on many things, such as our nervous system make-up and our emotional responses to painful experiences. One thing that has been agreed upon, however, is that pain is a message that tells us something is wrong.

It has been said that pain is the most common, costly, and disabling disorder we know. From chronic headaches to low back pain to arthritis, and so much more, pain impacts millions of people. Pain disrupts our jobs and our lives. It plays havoc with our emotional selves and our relationships with others. Pain has the power to color your world. It’s important then to understand how it is experienced in the body, how it impacts our emotions and lives, and how to manage it. We’ll look more in-depth at how pain impacts our emotions and lives as well as pain management techniques in parts 2 and 3 of this series. For now, let’s explore our perception of physical pain in our bodies.

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Let me pause briefly to mention an excellent resource on this topic, Reversing Chronic Pain, by Maggie Phillips, PhD. Many of the ideas and insights I have gleaned for this blog post…and plan to use for the next two posts in the series…have come from this book. Bruce N. Elmer, PhD blurbed about this book: “Maggie Phillips has written the first truly multi-modal, mind-body therapy self-help book for people with chronic pain. She offers usable, nuts-and-bolts techniques that can be used by readers in pain and pain professionals alike.”

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Types of Pain

In order to better understand and conceptualize, pain has been categorized into several different types. Below is an overview of some of the types of pain that are described in the medical and neurological world:

• Acute pain usually is experienced when you have an accident or injury to your body resulting in predictable patterns of pain that usually requires some type of treatment. Pain is considered acute if it lasts less than six months.
• Chronic pain is also known as persistent pain. According to the website, myDr, chronic pain can be caused by “ongoing tissue damage, such as in osteoarthritis. However, in some cases no physical cause for the pain can be found or pain persists long after the injury has healed.”
• Nociceptive pain, like acute pain, “is caused by any injury to body tissues, for example, a cut, burn, or fracture (broken bone). Postoperative pain and cancer pain are other forms of nociceptive pain. This type of pain can be aching, sharp or throbbing. Nociceptive pain can be constant or intermittent and may be worsened by movement or by coughing, depending on the area it originates from.” (myDr)
• Neuropathic pain is “caused by abnormalities in the system that carries and interprets pain – the problem may be in the nerves, spinal cord or brain. Neuropathic pain is felt as a burning, tingling, shooting or electric sensation. People with neuropathic pain may feel pain from stimuli that are not normally painful, such as light touch or cold. They can also be more sensitive than normal to stimuli that are usually painful.” (myDr)
• Muscle pain, based on physical mechanics of the body, is one of the most common types of pain. Muscle pain is characterized by muscle spasms that occur when the body contracts all the muscles near an injured or painful area of the body, in an attempt to protect or immobilize that body part. Unfortunately, spasms can result in further spasms due to the pain they generate themselves. Dr. Maggie Phillips refers to this in her book (see above) as a “vicious circle of pain-spasm-pain-spasm. So, what began as a beneficial protective device goes awry when the body becomes stuck in the mode of sounding the alarm.”
• Referred pain is another type of pain that is caused by muscle spasms. Referred pain is experienced in a different location from that of the spasm. Dr. Phillips writes, “For example, repetitive pain in the right arm, such as that resulting from carpal tunnel syndrome, may trigger pain in such “strange” places as the left shoulder or the thoracic mid-back area, because of a chain reaction through what are known as myofascial trigger points. Trigger points are created by injuries, straining of muscles, and various types of stress reactions.”
• Nerve pain is a type of pain experienced when nerves are injured. According to Reversing Chronic Pain, nerve pain may also occur “when damaged nerves regenerate imperfectly, causing new nerves to fire randomly and in error, so that they send pain signals to the brain even in the absence of pain.”

How Do We Sense Pain?

My interest in the subject of pain was piqued when I studied for my Interactive Guided Imagery(sm) certification through the Academy for Guided Imagery. David E. Bresler, PhD was my mentor throughout this program. In addition to his expertise in Interactive Guided Imagery(sm), Dr. Bresler was the former Director of the UCLA Pain Control Unit. He has written extensively on the topic of pain, including his book, Free Yourself From Pain. In this book, Dr. Bresler describes pain in a very reader-friendly way:

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OK, But How Does It Really Work? The Pain Pathway

At this point, it’s time for a confession. I am fascinated with how the brain works. This is just one of the more geeky things about me. I love to understand as much as possible about how people behave…how they feel…how they think. There are many ways to investigate all of this. Looking at how our brains function is just one. How do we sense pain? If you’re up for a wee bit of scientific exploration, come on board! I promise it will be only for a moment or two…or three.

One of the best ways I know to explain something is through storytelling. If I can put an image along with an explanation, then I have a better chance of understanding it. My story is a slightly re-imagined retelling of the explanation given on the myDr website (thank you all for your explanation!). Here goes:

1. Imagine that you’ve pricked your finger with something sharp. You feel pain…but how? Pricking your finger causes tissue damage to the skin on your finger. This tissue damage is registered by tiny pain receptors in your skin.
2. Each tiny pain receptor in your finger is actually one end of a nerve cell (called a neurone). That neurone is connected at the other end to a long nerve fiber (called an axon). And that long nerve fiber is bundled with many other long nerve fibers that are called a peripheral nerve. So…we are progressively moving from smaller to larger nerves. And…here’s the cool thing…what started in your finger is now moving it’s way up your arm. But where is it heading, you might wonder?
3. To the spinal cord in your neck! More specifically, it’s going to an area in your spinal cord called the dorsal horn. Here, electrical signals are transmitted from one neurone to another across junctions (called synapses) by means of chemical messengers (called neurotransmitters). Can you imagine this? All of the activity that happens in the dorsal horn? I sort of think of the dorsal horn as a place like Grand Central Station on water. Here comes a neurone! OK guys, we’ve got to get it’s electrical signal over to the other terminal. It’s headed west! All right, I’ve got transport for it on Neurotransmitter One…all aboard!
4. But, it doesn’t end there. Once that neurone has safely crossed the junction, without losing it’s connectivity, it is then signaled all the way up to the brain!
5. Our pain receptor friend has made it to the brain. We’re almost home! The signals pass to the thalamus, which is another sorting station, a little bit like the Grand Center dorsal horn. The thalamus, however, makes major decisions about where the signals go next. It can go to three different locations: 1) the somatosensory cortex (responsible for physical sensation, 2) the frontal cortex (in charge of thinking), and the limbic system (linked to emotions). We made it!
6. And here, my friends, is the Cliff Notes conclusion of this story:

Coming to a Speedy Conclusion

Aren’t our bodies remarkable? I know pain is not a pleasant feeling, but isn’t it something to marvel at the complexities of our bodies and how they function?

Have you ever thought about how quickly we register physical sensations? Just consider the finger pricking scenario above. If you pricked your finger, how long is it before you feel the pain of it? Imagine, too, the sheer distance that those receptors have to travel just to reach the brain. Talk about speed!

According to James Dillard, MD in his book, The Chronic Pain Solution, there is some research indicating that “dull pain or itching travels 0.5-2.0 miles per second; sharp or burning pain travels 5-35 miles per second, and soothing touch travels 35-75 miles per second.” This means that the sensation of a soothing touch can out-pace dull pain or itching…and possibly be perceived by the brain faster than sharp or burning pain! When I read this, it made me think about the possibility of soothing touch over-riding pain as a pain management technique…thanks to our wonderful nervous system!

Related to this is a much researched topic called the Gate Control Theory of Pain. First proposed in 1965 by Ronald Melzack and Patrick Wall, the Gate Theory of Pain “asserts that non-painful input closes the nerve ‘gates’ to painful input, which prevents pain sensation from traveling to the central nervous system.” (Wikipedia)

In her book, Reversing Chronic Pain, Dr. Maggie Phillips writes about the Gate Control Theory of Pain:

“Pioneer pain researchers Melzack and Wall discovered that certain circumstances ‘open the pain gates’ governed by the dorsal horn in the back of the spinal cord so that pain messages are relayed without interruption to the pain centers in the brain, and that other experiences ‘close the gates’ and stop the pain signals from ever reaching the brain.” She goes on to write: “Soothing sensations such as direct pressure and the touch of massage travel up to seven times faster, for example, than sharp or burning pain. This means that if soothing as well as painful sensations enter the dorsal horn at the same time, the faster, more pleasant sensation will prevail, blocking transmission of the slower, painful one. This fact brings good news for the pain patient!”

Maggie Phillips, PhD

Although more recently there has been some research that questions some of the findings made in the Gate Control Theory of Pain, it is my belief that this information is still valuable and pertinent in the scientific study of pain. I have personally utilized soothing sensations to compete with the painful sensations in my body, with positive results. This was also reported to be helpful by my clients I counseled with in the past.

How do we sense pain? Pain is real. Pain impacts our lives in many ways. I believe that one of the best lines of defense we have to deal with any problem, such as pain, is to understand more about it. When we understand something…the what, why, and how of something…we are more capable of planning our response to it.

We’ll continue this discussion, When You or Your Loved One is in Pain, next time. As always, your feedback is appreciated!

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