Imagined movements in spinal cord injury pain patients improves pain and restores cortical activation patterns to normal

A recent study (reported at IASP 2010 in Montreal) enrolled 13 patients with pain below the level of spinal cord injury into a 6-week training program employing 30 mins of imagined movements and sensation in painful limbs every day. Participants kept daily pain diaries and functional MRI (fMRI) scanning was performed both before and after the training program. Healthy controls were also scanned at baseline for comparison purposes.

The fMRI scan below shows activity in normal subjects in response to executed movement of the right hand. Activity is primarily in the primary motor and somatosensory cortices and supplementary motor area.

This next image shows brain activity in response to the same movement in spinal cord injury patients before imagery training. Notice that activity in motor circuits is considerably lower compared to normals.

This final image shows brain activity in the same spinal cord injury patients after the 6-wk mental imagery program. The activation maps look very similar to the healthy controls, with activity in the motor pathways.

Imagining pain can make it so

Perhaps one of the ways in which chronic pain reinforces itself is because people are exposed to the pain either constantly or repeatedly (in the case of recurring pain conditions) and so become exceedingly familiar with how it feels. This familiarity can fuel more complete and vivid imagining of the pain experience, which may very well exacerbate the pain. Indeed, it may very well that it is not fear per se that is the problem when people anticipate pain, but rather than they are imagining what the pain will feel like and it is the mental “picture” of the pain in advance of any actual pain, which evokes fear.

Evidence now exists that simply imagining pain can actually activate much of the same pain circuits in the brain that are typically involved during the experiencing of painful stimuli.

Allodynia is a condition in which normally innocuous or even pleasurable tactile sensations are perceived as painful. Kramer et al (2008) showed that by imagining touch as painful (imagined allodynia) activates the same neural structures as actual allodynia. They divided healthy participants into two groups. The first group had previously been exposed to experimentally induced allodynia within the past 6 months. The second group had no experience with allodynia and so did not know what touch-evoked pain is like. Both groups received tactile stimulation on hand and then the other, but they were asked to imagine that the sensation on the right hand was painful. Non-painful tactile stimulation activated contralateral S1 and S2 (see top panel of figure below). During imagination of allodynic pain in the right hand, there was activation in the ACC and Insula and medial frontal cortex in addition to contralateral S1 and bilateral S2 (see lower panel of figure below).

Thus, people who have had prior experience with allodynia are able to conjure up the experience in their imaginations and when they do, the brain regions normally associated with painful touch sensations become activated. Those with more allodynia experience showed more pronounced activation in the contralateral S1, mid insula, inferior frontal cortices, ACC and ipsilateral amygdala (see figure below):

The terrible privacy of pain

I am currently involved in conducting a study in which chronic pain patients keep a diary of their daily events, whom they’re with and how they feel. Before beginning the study they must come to an Orientation session. It has been very tiring running what seems to be an endless stream of these sessions but the opportunity to meet and talk to such a wide range of people of chronic pain patients, many of whom have suffered with their pain for many years, has been extremely inspirational. Their individual experiences differ, of course, but one thing that many of them identified as most troubling was that they felt totally alone in their pain. One woman told me that when she exerted extra effort to manage her pain, others around her thought that she wasn’t experiencing pain and so they withdrew their concern, offered less help. In a way stoicism is punished — the more they attempted to cope, the less support they received!

Pain is intensely private — perhaps the most private and subjective of all health ailments. There is no blood test or x-ray or any other objective measure that will identify people in pain or indicate how much pain their in or how much they’re suffering. Now, of course, one thing that you can do is to educate family and friends about your pain and to remind them that your efforts at management do not mean the pain has been eliminated. But it is apparent to me that people who have not experienced something themselves cannot never truly understand it. And that’s why there’s no substitute for networking with others who know what it’s like, who understand, who can commiserate, who can offer valuable information and practical advice. Local support groups can be useful but online support sites offer many advantages including groups with very specific types of certain conditions (local groups may not have enough people, but the Internet is open to the world), access to support and help at any time, and is more friendly to people who are shy and introverted.

The case of the disappearing pain

Last summer I was teaching a course in Positive Psychology at the University of Toronto. The summer courses are compressed from the normal 12 weeks to only 5 weeks so the schedule can be very challenging. One day during this period I was bending down to pick something up at home when a horrible snapping sensation occurred in my lower back, quickly followed by violent and excruciatingly painful muscle spasms running down my back and legs. My muscles had tightened up such that I was leaning to one side and couldn’t straighten myself. The pain was intense. Just thinking about moving caused painful muscle spasms.

This was actually not the first time I had this problem. I had first experienced in when I was in my early twenties attending grad school in Memphis. The pain is very intense and debilitating and lasts for about a month before easing. But this time was different. I had a course to teach. I had to get up in front of class and lecture for 2-3 hours twice a week. How the hell was I going to do this? I didn’t want to send out a notice canceling a lecture, not just because I’m such a devoted teacher but because I really loved to teach. I didn’t want to cancel because I would feel cheated. But I could barely stand for 3 minutes let alone 3 hours. What could I do?

Well, I decided that, dammit, I was going to teach that class if I had to do it while sitting, or even laying down! So I asked my wife to drive me to school. She walked with me to class while I pushed our baby stroller so that I would have something to hold on to while walking, and she helped me to hook up my computer to the projector. I took a chair and put in front of the class and sat down on the chair. I was in a great deal of pain. The trip in from the car was very tiring. I announced to the class what had happened to me and that I may have to lecture while sitting and then I began my lecture. As I was talking I felt the compulsion to get up and move around, to point to the screen, to animate myself.

I then attempted to stand up to do so and when I did I noticed a most remarkable thing. I felt almost no pain. That’s right — almost no pain! I stood and delivered the entire 2 1/2 hour lecture with almost no pain. But that’s not all. I was so happy that I had succeeded in delivering the lecture and that my pain had substantially receded that I walked with my wife to a nearby Starbucks to treat myself to a Latte. As I began to walk towards the coffee place, I could feel the pain returning, my muscles tightening, my body contorting once again. By the time we reached Starbucks I was racked in pain once again.

How did this happen? I believe that this most remarkable case of disappearing pain was caused by a large dose of endogenous opioids (endorphins) elicited by a threat. It has long been known that the perception of the threat of injury elicits the fight-or-flight response, one component of which is the release of opioids to numb pain. This natural analgesia is adaptive for if organisms were hobbled by pain while attempting to escape threat, they would likely not survive. For me, a failure to deliver that lecture represented a threat in many ways. It was the first full undergrad class I had taught so I felt the need to prove myself. I wanted to get great student evaluations so that I would get the opportunity to teach again. To have canceled that class would have thus posed a substantial threat to me.

For me this event was a personal reminder that we have evolved to survive and that when we think we just can’t make it, the body reveals a strength that we never knew it had.

How the National Institutes of Health (NIH) spends its money

Want to know how much the NIH is spending on research in various areas? Check out their Research Portfolio Online Reporting Tool (RePORT) athttp://report.nih.gov/budget_and_spending/index.aspx. Yes, I already checked on how much they devote to chronic pain research… It’s was 1% of their 2008 budget! Doesn’t sound like enough considering that chronic pain affects 30% of Americans!

Technology Review article on how chronic pain associated with changes in the brain

I discovered an article appearing in a 2007 issue of Technology Review magazine discussing pioneering research showing that persisting pain is associated with distinct changes in the brains of people suffering from chronic pain.

For example, one study by A.V. Apkarian at Northwestern University found that one part of the prefrontal cortex known to be involved in decision making appears to have shrunk in chronic pain patients, while another part involved in emotion is hyperactive, suggesting that the emotional component of the pain experience grows over time, while the sensory facet diminishes.

The changes in brain morphology and function associated with chronification of pain, is often referred to as maladaptive plasticity. Neural plasticity refers to the brain’s ability to re-wire itself in response to experience (learning) and even injury. This, of course, is mostly a good thing. But as we know from our propensity to take on bad habits, the brain’s ability to learn is not limited to learning good things.

Check out the article athttp://www.technologyreview.com/biomedicine/19715/

MD Anderson Pain Research Group

The Department of Symptom Research at the MD Anderson Cancer Center is a multidisciplinary team consisting of researchers and practitioners who are concerned with developing and implementing better methods of cancer symptom assessment and treatments. They have clinical trials underway focusing on educational, behavioral and medical interventions for cancer pain and fatigue.

Perhaps the most well-known accomplishment of this center is the development of the Brief Pain Inventory (BPI), which was developed by Dr. Charles Cleeland for the rapid assessment of pain in people with cancer. Here’s a link to the BPI User’s Guide.

Pain & the Law

At first I thought that this sounded only slightly more interesting than any other area of law, which is to say, not very interesting. However, the people behind this site are concerned with some very important issues in the management of pain.

We now know that opioid therapy can be effective at reducing pain and improving quality of life. Further, we know that the use of opioids is not associated with the degree of addiction and abuse previously thought to be the case. Despite this, opioid therapy is not being offered to so many pain patients who stand to greatly benefit from its use. It is believed that current laws and regulations, intended to curb misuse and abuse, have the unintended consequence of discouraging their application. Physicians claim that there is a threat of legal sanctions and penalties associated with the use of opioids, and this compels them to steer clear of opioid therapy.

The site is a collaboration between the Center for Health Law Studies at Saint Louis University, and the American Society of Law, Medicine and Ethics, funded by a grant from the Mayday Fund. I encourage you to take a look at this site.

The website can be found at http://www.painandthelaw.org/index.php.http://www.painandthelaw.org/index.php

Important questions about the placebo response

The placebo response is a wonderful demonstration of the potential of the mind to bring about almost magical healing powers. But though there has been an amazing surge of knowledge about the placebo response over the last several years, there is still much we don’t know, and I think the most exciting times are yet to come. Here are some of the questions I think are particularly interesting, mainly because their answers have important clinical implications.

Not everyone is a “placebo responder”. Why? Perhaps we’ve been looking at this question the wrong way. We’ve been asking, “what makes a placebo responder?” The answer to this question has proven elusive. Perhaps we should be asking, “what prevents someone from being a placebo responder?” We actually already have one answer to this latter question. A fascinating study by Benedetti et al (1995) has shown that Cholecystokinin(CCK) acts to limit placebo responses. When given a CCK antagonist (e.g., proglumide) a considerably larger placebo response occurs. So CCK limits the placebo response and a drug that removes CCK from the picture, removes this limit. For this reason, the CCK antagonist proglumide has been called a “placebo amplifier”.

The CCK discovery is a fascinating one but the question of what limits the placebo is far from fully answered. CCK cannot turn non-placebo responders into responders.

Swearing found to increase pain tolerance

Participants in a recent study at Keele University in the UK were told that the researchers were investigating the degree of stress that various forms of language elicit during stressful experiences and then asked to plunge their hand into a tank of cold water and keep it there for as long as they could while repeating a word of their choice.

They found that swearing people could keep their hand submerged significantly longer than their non-swearing counterparts, perceived the sensation as less painful and exhibited a greater increase in heart rate (see figure below).

The authors suggest that swearing might increase fear-related emotional responses, which have been linked to analgesia responses. They also posit that swearing might elicit aggressive tendencies, which can prompt greater stoicism or machismo. Both of these putative mechanisms are purely speculative and it remains to be seen why exactly swearing helps to reduce pain sensitivity.

PubMed Link: http://www.ncbi.nlm.nih.gov/pubmed/19590391

Nightshirt worn to bed unobtrusively measures stages of sleep

The grand majority of sleep research requires that participants spend at least one night and sometimes many nights in a sleep lab hooked up to equipment capturing a wide array of measures including brain and muscle activity, eye and body movements, and respiration. Getting people to come to a sleep lab has several disadvantages. It's inconvenient for individuals who must disrupt their lives to participate and it necessitates sleeping in a strange environment, away from family.

Recently, a number of interesting products have appeared that claim to be able to measure various objective indices related to sleep.

One of the more interesting I've seen is the Somnus night shirt. The shirt uses thin and flexible respiration sensors that have been directly applied to the shirt's fabric. The shirt's developers claim that respiration data are all that's needed to detect whether someone is awake or asleep and their stage of sleep. For example, during REM sleep, respiration is irregular, whereas in non-REM sleep respiration follows a regular pattern.

I've emailed the company to find out more about the shirt, including what studies have been conducted verifying the validity of their claims and the accuracy of the shirt. If they work, such portable, inexpensive devices that can be used by individuals at home opens up many exciting new research and clinical possibilities.

Link to the company's website.

Link to an article about the device in Technology Review.