pain relief

Hypnosis: Response expectancies?
Let’s explore the proposed mechanisms in hypnosis as I wander through the subject this week.
According to some researchers, response expectancies, or ‘the expectation of one’s own non-volitional reactions to situational cues’ are thought to play a major part in both hypnosis and placebo responding. Let’s translate that: a person’s belief that they will respond to something may lead to them actually responding. Possibly the original ‘mind over matter’!

Both hypnosis and placebo (or meaning response – see Dan Moerman for more details on this!) are complex effects that are not yet really understood, except to confound most RCT’s and to provide food for thought for philosophers and psychologists and lay people alike. In this paper, response expectancies were experimentally examined to see whether they have a mediating effect on the effect of ‘suggested’ or placebo analgesia. The methodology is a wonderful design developed by Barron & Kenny, where separate sets of mediator analyses are performed in which the no-treatment control condition is contrasted in turn with each of the treatments. Performing the analyses in this way isolates the mediator function of response expectancies in each treatment. Three regression equations were estimated, to in turn, identify the strength of the relationship between each variable. For more of the maths, go to this paper!

What did they do?
A group of students were recruited to take part in a study examining the effectivenes of ‘an experimental topical anaesthetic’. They were not informed initially that hypnosis was part of the study, to minimise the chance that they would inadvertently over-report their levels of pain to ‘give room’ to pain reduction with hypnosis.

Pain intensity was measured using an 11 point graphical scale 0 = no pain, 10 = pain as intense as one can imagine, and taken every 20 seconds while their finger was put in a pain stimulator for one minute (cruel people these psychology professors!).

Pain expectancy was measured using the same 11 point scale and the score was taken immediately after the baseline pain rating and indicated the level of pain the participants expected to be like if they put their finger in the device without any intervention.  During the experiment, participants were asked to use this rating immediately after they had experienced a pain control intervention (but without putting a finger in the stimulator) indicating what participants expected the pain would be like while using the pain intervention they had just experienced.

The Carleton University Responsiveness to Suggestion Scale (CURSS) was used to establish how how much each participant responded to suggestions contained in the scale. This is a measure of three types of suggestability: ‘Objective suggestibility’ : what participants think an observer would have seen them do in response to each suggestion.
‘Subjective suggestibility’ : indicates participants’ internal experience of each suggestion.
Involuntariness’: assesses the extent to which participants experienced each suggestion as occurring automatically and without a feeling of effort.

The torture instrument? This was A Forgione-Barber Strain Gauge Pain Stimulator. Details shall remain secret, suffice to say that it squashes the fingertip so that it hurts (ouch! remind me not to be a psychology student).

There were two phases to the experiment: the preparation phase, during which participants were given information about pain management, and offered the chance to try a pain intervention without actually submitting to the finger device. They were then asked to rate what they thought the pain would have been like had they actually had the device applied to their finger while using that coping strategy.

During the intervention phase, participants were administered the intervention while actually submitting to the pain device, and making intensity ratings.

The interventions

Hypnotic analgesia – in the preparation phase, the participants listened to a tape recording presenting information about hypnosis (correcting myths), using the actual hypnotic induction from the CURSS, information about hypnotic analgesia, and an opportunity to experience a short ‘glove anaesthesia’.  In the intervention phase, participants had the same glove anaesthesia hypnosis, but actually got the pain.

In the ‘imaginative analgesia’ condition, participants experienced the same glove analgesia suggestion used in the hypnotic analgesia condition, but without the hypnotic induction or information designed to correct misconceptions about hypnosis. The glove anaesthesia was represented as a ‘guided imagery’. In the preparation phase, participants were asked to ‘use your imagination’ to experience the glove analgesia, while in the intervention phase, the induction was given ‘live’, and you guessed it, the pain was live too.

The placebo condition involved an inert solution presented as an experimental, local, topical anaesthetic, but was actually oil of thyme, and iodine, presented in a brown bottle and labelled ‘Trivaricaine: Approved for Research Purposes Only’. During the preparation phase, participants were told about the effects of analgesia, with a lot of showmanship to demonstrate how ‘powerful’ the liquid was. During the intervention phase, participants had this liquid applied, received the pain, and rated their pain.

The final group were given a ‘no treatment’ condition – They waited the same length of time between the initial rating of pain expectancy as the other three groups, then received the same pain, and asked to re-rate their pain.

I won’t detail the rest of the methodology, but it followed a random assignment format to the four conditions, with equal numbers of males and females to each condition. Strategies were undertaken to minimise the potential for demand bias, ‘hold-back’ effect, and of course, participants were free to withdraw if they chose to.

As usual, I’m not going to go through all the statistical detail – it’s well-documented in the paper, and you should read it if you want to really scrutinise the quality of this study.

As hoped, there was an effect from giving people pain, and the scores differed depending on the pain interventions given – scores did change, with the no-treatment group reporting more intense pain than those in the placebo group, and those in either of the hypnotic groups.

The object of this experiment, however, wasn’t to establish whether hypnosis had an effect – it was to examine the effect of expectancy on pain intensity, and to look at suggestibility.

First up, suggestibility ‘subjective and involuntariness dimensions of hypnotic suggestibility moderated the effect of the hypnotic analgesia treatment’ – what this means is that aspects of suggestibility do influence how effective hypnotic analgesia can be.

Then expectancies: ‘the effect of each of the three treatment conditions on pain intensity was partially mediated by response expectancies. The extent of mediation by response expectancies appeared to be greater in the placebo condition than in the hypnotic and imaginative analgesia conditions.’

What does this mean? The expectation that pain will be reduced influenced each of the treatment implemented – and more so on the placebo treatment.

Now that’s interesting!
Something about the beliefs that people place on not just the ‘active ingredients’ but the showmanship, ritual, and ‘hype’ involved in a treatment has an effect on how much pain relief a person achieves. Doesn’t that make you think about advertising for pharmaceuticals, the interpersonal skills involved in treatment – and how careful we need to be when discussing treatment options. However well-intentioned, I don’t think we can realistically offer impartial advice on different treatment options because we’re human – so how can a patient not be influenced by our (inadvertent) enthusiasm?

Milling, L. (2009). Response expectancies: a psychological mechanism of suggested and placebo analgesia Contemporary Hypnosis, 26 (2), 93-110 DOI: 10.1002/ch.379

Placebo and social observational learning
One of the greatest enigma in health is the human response to placebo. Placebo itself is an inert substance or treatment that has no effect – yet humans can respond with physiological changes as if the substance was active. For years some unscrupulous medical practitioners have used this response in people experiencing chronic pain as evidence that their pain is ‘all in the head’, or that their problem is ‘psychosomatic’, whereas other even less scrupulous snake oil merchants have used this as a way to sell things like crystals, colour therapy and even coloured lotions for the ‘healing’ of pain and other assorted symptoms.

Colloca and Benedetti are two of the most respected researchers into the phenomenon of human response to placebo. They have used a wide range of experimental methodologies to investigate placebo, and this one is yet another to add to their extensive repertoire.

In this study, hoping to investigate the effect of learning through observing someone experience placebo analgesia as compared with first-hand experience and verbal suggestion alone. The premise is that some placebo analgesia is influenced by expectancy, some by conditioning, some by reinforcement – and in this experiment, by social observational learning.

Social observational learning is where an individual watches another person and learns through ‘vicarious learning’.
In this experiment, the participants were asked to sit beside a person who had been trained to simulate the
experimental session. This person ‘always rated as painful the stimuli paired to red light and as non-painful the stimuli paired to green light. In this way, he simulated an analgesic benefit following the presentation of the green light.’ After observing this, the participant underwent his or her own experimental session.

The other two conditions were – one in which the person was conditioned using an electric shock paired with the red light, and were told a ‘sub-threshold’ electric shock would be delivered paired with a green light. An electric shock was never paired with the green light at all, leading to a conditioned response where the green light produced an analgesic effect. As the authors state: ‘It is important to stress that the stimulus intensity was surreptitiously reduced, so that the subjects believed that the green light anticipated analgesic effects’. This is a standard conditioning process used in Colloca and Benedetti’s placebo experiments.

The final condition was one in which the participants were told that the green light would be paired with an analgesic just before the shock was delivered – the subjects were told ‘that a green light would anticipate a stimulus that was made analgesic by delivering a sub-threshold electrical shock on their middle finger. Conversely, a red light would anticipate the deactivation of this electrode and thus a painful stimulation on the dorsum of the hand. Actually, all the stimuli were set to go off at the same time as the light.’

What were the results? Quite startling, actually! The subjects who had observed the analgesic effect in the demonstrator rated the green-stimuli consistently less painful than the red-stimuli. And every single green-stimulus was rated lower than the red. This effect simply from watching someone else apparently receiving an analgesia – when actually nothing was being delivered.

The experiential group, those that went through the conditioning procedure themselves, also reported reduced pain when the electric shock was paired with a green light. And finally those who were given a verbal instruction that they would experience analgesia paired with the green light also reported lower pain, but this dropped off fairly quickly after the initial instruction.

So there you have it – somehow by watching someone else obtain an effect, these participants developed a strong and sustained analgesic effect. What is it they were seeing? We’re not sure yet – but Colloca and Benedetti suggest that empathy has something to do with it, because there was a relationship between empathy and the response as measured on the Empathic Concern subscale of the Interpersonal Reactivity Index, a measure often used to investigate trait empathy. This wasn’t demonstrated for other subscales of the IRI.

What can we learn from this? Well, firstly it’s important to recognise that this is an experimental situation in a lab with volunteers – all female – who may not be like you or me! But findings like this can suggest that when we observe someone else reporting and behaving as if a treatment provides good results, we are likely to have a similar effect, provided of course we’re high in empathy. Similarly, but not quite as strongly, we respond to being conditioned ourselves to experience analgesia through a placebo.

Maybe an experiment like this will see the end of celebrity endorsement of magnetic underlays for the bed?!

Colloca, L., & Benedetti, F. (2009). Placebo analgesia induced by social observational learning Pain DOI: 10.1016/j.pain.2009.01.033
Colloca L, Benedetti FPlacebo analgesia induced by social observational learning, PAIN (2009),

Pain management: CBT or a CBT perspective?

There is a bit of a misconception about CBT for chronic pain management. Some people think that it consists only of cognitive behavioural therapy as it is used for depression or other mental health problems. And this often means people think mainly of cognitive therapy as conducted by clinical psychologists – meaning that clinicians from other professions can lack confidence to be involved.

I thought today I’d outline the views of one of the ‘founding fathers’ of the cognitive behavioural perspective for chronic pain, Dennis Turk. In a paper by Turk and colleagues Kimberley Swanson from University of Washington School of Medicine, Department of Anesthesiology, Seattle, and Eldon Tunk, Emeritus Professor in the Department of Psychiatry and Behavioural Neurosciences, McMaster University, Ontario, the psychological models used to conceptualize chronic pain—psychodynamic, behavioural (respondent and operant), and cognitive-behavioural are described. They also briefly review treatments based on these models.

One of the main points of this editorial paper is, in their words, ‘to differentiate the cognitive-behavioural perspective from cognitive and behavioural techniques and suggest that the perspective on the role of patients’ beliefs, attitudes, and expectations in the maintenance and exacerbation of symptoms are more important than the specific techniques.’ (more…)

History of pain and pain management

One of my colleagues at Burwood Pain Management Centre presented an interesting education session on the history of pain management – it made us all feel very grateful we are now in modern times because electric eels placed on the painful part, bloodletting and death from ingesting all manner of herbal potions just don’t appeal! (Oh, but it’s ‘natural’!)

The presentation did make me curious (OK so that’s my strangeness outed – as if you didn’t know!) so I thought I’d see what information’s about on the internet on the history of pain treatment and management.

Just before I link to some of the sites I found, I thought I’d give you this wonderful image – and it’s in modern times…

Anyway, The John C. Liebeskind History of Pain Collection contains some of the most authoritative and extensive collections of post-World War II pain history documents.

The focus of this collection is ‘on the origins, growth, and development of the international, interdisciplinary pain field’ and one of the major achievements is the exhibit called ‘The Relief of Pain and Suffering’ which contains some great information on the attempts to relieve pain prior to the 19th Century.

It has several wonderful engravings of late 1800’s pharmaceuticals such as the one below – note it is recommended for children ’10 drops every four hours’.

The UCLA Online Biomedical Library also has links to a large number of allied internet resources. One of the ones that really tickled my fancy was History of Medicine Images collection. If you search ‘pain’ 85 images depicting pain and pain relief in history are located – and if you didn’t feel squeamish looking at that bloodletting picture above, some of these will certainly turn your stomach! They’re primarily old engravings and line drawings of things like ‘The blacksmith turned toothpuller’ and ‘woman in labour’. Information about copyright is provided, so you can see how to access these images for use in presentations perhaps!

Now turning to more modern times, our fascination with magnetic, electric, hot and cold devices with special ‘healing’ properties hasn’t waned. While I can accept that in the 1800’s, when evidence-based methods were scarce, I cannot understand why we have open advertising for things that just don’t stand up to close scrutiny. I clearly recall people coming to Pain Management with magnets like these in the mid-1990’s…, and the ‘magnetic underlay’ can still be bought today – endorsed by prominent sportspeople and the like. The history of electric devices for pain relief goes as far back as the electric eel mentioned above, but carried on with ‘Dr Bell’s Electro Appliance’, an electrified belt that was advertised as ‘This appliance is for Sexual Debility, Nerve Troubles, Stomach kidney, Liver, Bowel or Bladder weakness, Rheumatism and other congested or weakened conditions of the system…’.

More recently? Well, this link leads us to an Electric Sympathetic Block for pain relief, and this link for transcutaneous spinal electroanalgesia. I’m not sure of the efficacy of this type of treatment – but it doesn’t seem to have developed too far from the original electric eel to the painful part, just perhaps a little less ‘natural’.

I hope you’ve enjoyed this diversion into the history of pain treatments – and that I haven’t scared you off coming back! Please, if you’ve got about 5 – 10 minutes, click into my Questionnaire on pain management strategies. I’m really keen to find out what definitions we use for coping strategies, and whether there is any agreement on what we use them for, and why we use them. Congratulations to the person who was first!! A social worker by trade, but I know nothing more about him/her, but thanks for being the first to answer!

Friday funny! or ‘Look how far we’ve come’

If you ever think that things in our world haven’t improved a bit, take a look at this advertisement!

See? Hopefully we won’t see anything like that again – there are a few other adverts I’d like to see the back of too, like the ‘magnetic woollen underlay to relieve pain’ and the ‘back brace’. Until they go, we’ll just have to be satisfied with this.