nestled

I’m so easily distr….oooh look! Shiny!


ResearchBlogging.org
Wouldn’t it be great if there was a simple way to help people avoid focusing on their pain, allowing them to just watch a TV programme or something, and not be bothered by some painful procedure? This is a dream for those health professionals who have to carry out painful procedures like take blood, drill teeth, change dressings, stretch body parts and so on. It’s also an area of great interest for researchers, because studying how distraction affects our experience of pain shows us a great deal about how our brains detect threat, process incoming information, encourage an adaptive response and so on. It’s probably also a really interesting area for people who like to inflict pain on others – in the name of science.

While the form of pain is different in experimental pain studies compared with chronic pain, we have learned a great deal about “psychosocial” factors through the many and varied experiments carried out. This study is yet another, but this time asked people with chronic pain to participate in a study that incorporated mechanical temporal summation, a distraction task, thermal threshold and tolerance testing, pressure threshold and tolerance testing, cuff pressure testing, followed finally by a conditioned pain modulation test. That’s a lot of pain!

The distraction test involved asking the participants to squeeze a handgrip dynamometer with their dominant hand. Two readings were averaged, and the participants told to “maintain a grip strength as uniformly as possible”, using their nondominant hand, with the maximal grip strength aiming to reach 20% of the dominant hand. This while the participants were undergoing a mechanical dot probe test.

In addition to these painful experiments, participants also completed a number of psychometric questionnaires: The Brief Pain Inventory, The Beck Depression Inventory, the Pain Anxiety Symptoms Scale and the Pain Catastrophising Scale. All well-known measures often used in chronic pain management.

After some statistical wizardry, what did these researchers find?

Well, very interestingly indeed, what they found was that people who tended to score highly on the PCS obtained a greater effect (reduction of reported pain intensity) on the temporal summation test than those people with lower PCS scores.

This is interesting for several reasons. The first is that temporal summation of pain was greater in the people who catastrophise – and this is a group of people who usually fare quite poorly in clinical situations including both acute and chronic pain. What I mean by this is that people who tend to catastrophise often become more distressed, have difficulty distracting themselves from their pain, and can “think the worst”and  therefore become more disabled by their pain. This applies in many different situations such as after orthopaedic trauma (Williamson, Gabbe, Cameron, Edwards, Richardson et al, 2009), after knee joint replacement (Riddle, Wade, Jiranek & Kong, 2010), low back pain (Sieben, Vlaeyen, Tuerlinckx and Portegijs, 2002) and many more. In this situation, however, they seem to fare better when they’re being distracted by doing something else – even something as simple and boring as squeezing a dynamometer.

The authors of this paper suggest that their experiment may have uncovered an important aspect of catastrophising – that when people are specifically tasked with something to distract their attention away from the painful stimulus, catastrophising has less effect. This could mean that an important aspect of catastrophising is the degree to which a stimulus grabs attention (or should I say, the degree to which people who catastrophise have their attention grabbed by something “interesting” or “threatening”).

It also suggests that perhaps one way of helping people who tend to catastrophise would be to facilitate distraction when they have to undergo painful procedures. Perhaps even use distraction as an effective means to reduce their overall pain experience, even in chronic pain – although this is pretty speculative.

Of course there are many if’s and buts about this study. The kind of painful stimuli used in this study is very different from that experienced by people with chronic pain in daily life.  These findings differ from some others in the literature, and it’s difficult to know how or why – perhaps the pain intensity was different, perhaps people who have to sustain attention over a long period of time such as for this study have some strange learning effects going on, and perhaps there are some other physiological effects of these kinds of acute pain tests. We don’t know.

What is really interesting, though, is that for once catastrophising had a benefit – and maybe we can learn more about how to use this benefit for people who otherwise struggle with their pain.

 

Riddle, D. L., Wade, J. B., Jiranek, W. A., & Kong, X. (2010). Preoperative pain catastrophizing predicts pain outcome after knee arthroplasty. Clinical Orthopaedics & Related Research, 468(3), 798-806.

Schreiber, K., Campbell, C., Martel, M., Greenbaum, S., Wasan, A., Borsook, D., Jamison, R., & Edwards, R. (2014). Distraction Analgesia in Chronic Pain Patients Anesthesiology DOI: 10.1097/ALN.0000000000000465

Sieben, J. M., Vlaeyen, J. W., Tuerlinckx, S., & Portegijs, P. J. (2002). Pain-related fear in acute low back pain: the first two weeks of a new episode. European Journal of Pain: Ejp., 6(3), 229-237.

Williamson, Owen D, Gabbe, Belinda J, Cameron, Peter A, Edwards, Elton R, Richardson, Martin D, & Group, on behalf of the Victorian Orthopaedic Trauma Outcome Registry Project. (2009). Predictors of Moderate or Severe Pain 6 Months After Orthopaedic Injury: A Prospective Cohort Study. Journal of Orthopaedic Trauma, 23(2), 139-144 110.1097/BOT.1090b1013e3181962e3181929.

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