Back Pain and Difficult Emotions

1
Back Pain and Difficult Emotions

The emotion of chronic pain
The emotion of chronic pain. Gwyn Photography/DigitalVision/Getty Images

My guess is that you know from personal experience depression and chronic back pain can come as a package. In fact, depression a common problem in people with painful spines. Sullivan, et. al., in their study published in the July 1992 issue of Pain, reported that people with chronic low back pain had about 3-4 times more depression than those in the general population.

And the more back pain you have, the more depression you may experience, according to Currie and Wang, in their 2004 study, which was also published in Pain (January) entitled "Chronic back pain and major depression in the general Canadian population."  The research in this study identified a direct linear relationship between the two.

Currie and Wang also found that while 5.9% of people in the general population had depression, the number jumped to 19.8% in the chronic back pain only population.

What creates this scenario - this connection between spine pain and your psychiatric health? The answer may well lie in your brain.

Sources

Currie, S.R., Wang, J. Chronic back pain and major depression in the general Canadian population. Pain. 2004 Jan.

Sagheer, M.A., Khan, M.F., Sharif, S. Association between chronic low back pain, anxiety and depression in patients at a tertiary care centre. J Pak Med Assoc. 2013 Jun;63(6):688-90.

Sullivan, M.J., Reeson, K., Mikail, S., Fisher, R. The treatment of depression in chronic low back pain: review and recommendations. Pain. 1992 Jul;50(1):5-13.

2
The Journey of a Pain Signal

Nerve cells.
Nerve cells. PASIEKA/Science Photo Library/Getty Images

To begin to understand the relationship between chronic back or neck pain and difficult emotions, we need to know something about how the nervous system creates feelings of pain. Key to our discussion is the central nervous system, which consists of your brain and your spinal cord.

Pain comes about when some type of stimulus - either mechanical, thermal and/or chemical - is elicited at a nerve ending (you have nerve endings all over your body) and travels to the spinal cord where it is then routed up to and interpreted by the brain.  

The central nervous system, especially the spinal cord, provides a "freeway" for nerves to relay these thermal, mechanical and/or chemical messages.  

While the real-time process of what causes you to feel pain is much more complicated, this is it in a nutshell.

Sources:

Guyton & Hall. Textbook of Medical Physiology. 11th Edition. Elseiver Saunders. 2006. Philadelphia. 2006.

Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Sunderland (MA): Sinauer Associates; 2001.

3
Acute and Chronic Pain Signals

Freeway
Freeway. Chris Hepburn/The Image Bank/Getty Images

But there's acute pain and there's chronic pain. Each has a different type of originating stimulus, travels a different route to the brain and ends in the brain in a different place.

The easiest way to understand and apply this distinction to your situation is with an analogy.

You might think of acute pain as fast and chronic pain as slow. The speed of transmission of the signals that eventually become your felt pain is slower for chronic pain than it is for acute.

Although each type of pain signal travels through the same main nerve-to-brain "freeway," so to speak (called the spinothalamic tract,) each originates from an entirely different set of pain fibers. 

The type of nerves carrying messages that will be interpreted as acute pain are thin, and can transmit their signals at a speed that's up to 150 meters per second (authors vary on this number). On the other hand, the kind of nerves that carry chronic pain are thicker and slower and transmit at speeds only up to 2 about meters per second.

So the analogy goes like this: Acute pain signals are akin to travel in a souped up race car on a smooth, empty freeway, while chronic pain is a ride in the old clunker.

Related: Compare acute pain signals to chronic pain signals.

Source:

Guyton & Hall. Textbook of Medical Physiology. 11th Edition. Elseiver Saunders. 2006. Philadelphia. 2006.

4
Acute Pain Processing Basics

Acute pain processing is fast - like a ride in an extreme performance race car.
Acute pain processing is fast - like a ride in an extreme performance race car. Colin Anderson/Photographer's Choice/Getty Images

The marvel that is your nervous system is equipped to respond very quickly when you are in danger of true harm. This is for your protection and is especially evident when the pain is acute. Let's take an example.

Say you burn your hand while taking a piping hot, fresh baked apple pie out of the oven. Most likely, you'll feel intense pain a second or two after you've touched the sizzling dish. 

As we talked about on the previous slide, it will only take but a second or two for you to feel this burning pain, which was elicited by a thermal stimulus (your hot baking dish). The nerves that the thermal stimulus travel on en route to the brain, again, are thin and fast, and can transmit the signals at a speed of almost 1/10th of a mile per second. Because of this, needless to say, you're very quickly notified that your hand hurts after this type of incident.

Another notable feature about acute pain signals is that they make it all the way up to your cortex - basically your "thinking cap."  The cortex is a very nimble interpreter of signals and therefore enables you to identify the exact location of the pain (in this case your hand.)

Once the brain decides the event is not causing you any real harm, it decreases the intensity of the communication signals associated with this singular event. In the case of the burned hand, after awhile you may feel some discomfort, but the extreme pain is gone.

Related:  Get to Sleep Despite Pain

Source:

Guyton & Hall. Textbook of Medical Physiology. 11th Edition. Elseiver Saunders. 2006. Philadelphia. 2006.

5
Chronic Pain Processing Basics

Chronic pain processing by the nervous system can be slow and stop and go - like riding in an old clunker.
Chronic pain processing by the nervous system can be slow and stop and go - like riding in an old clunker. Heritage Images/Hulton Archive/Getty Images

While both pathways connect to the "thinking cap" mentioned above, the chronic pain tract appears to connect to several areas of the lower part of your brain that associate the experience of pain with suffering. The ability of these endpoints to interpret the signals they receive is rudimentary compared to the "thinking cap" cortex.

The signals that travel through the chronic pain pathway are generally felt as diffuse, dull, continuous and/or throbbing; they are not succinct.

People with this type of pain tend to have difficulty pinpointing the exact location. Identifying the general region is usually as far as they get.   

Another difference between chronic and acute pain signals to the brain is that the originating stimulus for chronic pain is, for the most part, chemical in nature, while acute pain stimuli are mechanical and thermal.  

Related: 5 Ways You may be Triggering Your Sciatica

Source:

Guyton & Hall. Textbook of Medical Physiology. 11th Edition. Elseiver Saunders. 2006. Philadelphia. 2006.

6
The Limbic System and Your Chronic Pain

The thalamus acts like a switch board that routes pain signals to various places in the brain.
The thalamus acts like a switch board that routes pain signals to various places in the brain. FPG/Retrofile/GettyImages

But the story doesn't end there. The area in the brain where the chronic pain signals terminate (called the thalamus) functions like a master switchboard that relays the signals to other places in the brain. One nearby area with a lot of connections to this dispatch central is called your limbic system. The limbic system consists of a number of structures that regulate things like drive, stress responses and emotions such as fear, and anxiety. The limbic system regularly receives pain signals from the thalamus.

About the thalamus and limbic system, Whitten, et al. in their report published in the Fall 2005 issue of the Permanente Journal entitled Treating Chronic Pain: New Knowledge, More Choices" says, "the complex interactions of all these areas define the patient's perception of pain."

Well, wow, you may say. That's complicated! True, and this is just a drop in the bucket when it comes to how pain is processed by your brain.  

So what can you do to help yourself have a better day in the face of chronic neck or back pain? How about taking Whitten, et al's advice and employ strategies help you process less pain?

Whitten, Christine, MD, Donovan, Marilee, RN, PhD, Cristobal, Kristene, MS. Treating Chronic Pain: New Knowledge, More Choices. Clinical Contributions. The Permanente Journal. Fall 2005. Vol. 9. No. 4.

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