Getting persistent pain and disability confused


As I read blogs and tweets and posts on social media, and even peer reviewed papers in journals, I often read that what we’re trying to do in sub-acute pain management is to prevent chronic pain from developing (note, when I talk about pain that goes on beyond healing, more than three months, or has no useful function, I may use the term “chronic” or I may use the more recent term “persistent” – they mean the same thing, except persistent has perhaps less baggage…).

I want to take aim at that focus – to prevent pain from persisting – and think carefully about it. Let’s take a 56 year old woman with a painful knee, a knee that’s been diagnosed as having osteoarthritis (OA). Now, although we have surgical management for OA (a knee replacement – uni-compartment or even a total knee replacement), in most cases surgeons are not enthusiastic about doing a knee replacement on a younger person, particularly someone who is active (plays netball, golf, runs, gardens). So if a knee replacement is not a thing – yet – what do we do? Most of us will know about the value of remaining active and fit, losing weight and maintaining good range of movement (see here for the NICE guidelines, 2017). We know that these things will maintain function – but they won’t stop cartilage deterioration (much, if at all), and they won’t stop the pain. No matter what we do – even medications are not always especially helpful – pain is likely to persist. Does that mean we’ve failed? Reading some of these blogs, it certainly seems it does.

Let’s take back pain – most of us will know back pain occurs periodically throughout life, from the time we’re teens, through to old age. In some people a single bout of back pain happens and then they’re fully recovered and never bothered again, but for many of us, we’ll be troubled with repeated bouts throughout our lives. And still others will have one bout than just never ends (Axen & Leboeuf-Yde, 2013; Vasseljen, Woodhouse, Bjorngaard, & Leivseth, 2013).  This is despite our best efforts to prevent the onset of low back pain, and to treat it effectively – pretty much all our treatments provide a small amount of help but only exercise has been shown to prevent a new bout after the first one (Choi, Verbeek, Wai-San Tam & Jiang, 2010) – and even then the evidence was “moderate” and only at one year.

So… when we begin to examine claims that by treating musculoskeletal problems early we can prevent pain from becoming chronic or ongoing, I think we need to stop and pause before letting the blood rush to our head.

If we can’t prevent pain from hanging around, what can we do? What is the aim of all this treatment?

Well, let’s take a quick look at the Global Burden of Disease (Hoy, March, Brooks, Blyth, Woolf, Bain et al, 2014). In this piece of work, “Out of all 291 conditions studied in the Global Burden of Disease 2010 Study, LBP ranked highest in terms of disability (YLDs), and sixth in terms of overall burden (DALYs). The global point prevalence of LBP was 9.4% (95% CI 9.0 to 9.8). DALYs increased from 58.2 million (M) (95% CI 39.9M to 78.1M) in 1990 to 83.0M (95% CI 56.6M to 111.9M) in 2010. Prevalence and burden increased with age.” [emphasis mine].

What this means is that although low back pain is not a fatal disease, that may well be the problem – people don’t die from low back pain, they live with disability all the days of their life. And worse, the burden of low back pain is increasing. And this is despite all the work we (you, me, the entire health system) is putting in.

If we can’t “get rid of” low back pain (and it looks like we don’t yet have the tools to do so), what are we trying to do?

Given our poor outcomes for completely curing low back pain, we need to aim to reduce the impact of pain on people’s lives.

And not just low back pain, but things like tennis elbow, frozen shoulder, neck pain, abdominal pain, pelvic pain, headache, migraine, osteoarthritis…

For a moment, let’s think about the effect on a person going through treatment, being promised that “pain education” will reduce their pain, that exercises will get rid of their pain, that gadget A or B will get rid of their pain, that treatment Y or Z will get rid of their pain. What do you think it feels like to be completely adherent about everything you’re being asked to do, but still feeling a failure because that pain does not go? Think of the language used by some of our colleagues – “failed back syndrome”? Who failed, exactly?

Before I get harangued for breathing the word that, ooops, our treatments don’t work very well, let me address the issue of “pain education” and pain intensity. Don’t forget that the only way we can know how much it hurts someone is by asking them. And our usual tool is that 0 – 10 scale, where 0 = no pain and 10 = most extreme pain imagined. Have you ever tried doing that on yourself? Seriously – how do you rate your own pain? Some of that pain rating is about how much we’re prepared to (capable of) putting up with. Some of that rating is about how bothered (fed up, distressed, frustrated) we are about our pain. Some of it is about “OMG I don’t know what this is and how long it’s going to go on for”.

What this means is that when someone gives an explanation it can –

  • make the experience less frightening,
  • less distressing,
  • more understandable,
  • less bothersome

and as a result, when we’re then asked for our pain intensity rating on that darned scale, we reduce the score we give our pain. It does not necessarily mean the pain has reduced in intensity – a pain scale is a means of communicating something about our experience, thus it’s a pain-associated behaviour with the purpose of communicating something. So if a person isn’t ‘convinced’ by our pain education, you know they’ll keep their score pretty high.

So, there are some people for whom we cannot reduce or get rid of their pain. It’s likely to persist. And it’s these people who can be viewed as “heartsink” patients, who hang around not getting better. Well, unless we begin looking at their experience and examine what they’re looking for (and believe me, it’s not pain reduction – it’s what pain reduction means they can do) we’re going to be stuck. And so will they. Let’s get it into our heads that pain reduction is not achievable for all, but reducing the impact of pain on life is something we can all help with. Let’s stop demonising the person who has to live with pain that doesn’t respond to all our ministrations and begin looking deeply at ourselves and why we avoid recognising that we can’t win ’em all. And let’s get on with the business of helping people do what’s important in their lives, irrespective of pain.

 

 

Axén, I., & Leboeuf-Yde, C. (2013). Trajectories of low back pain. Best Practice & Research Clinical Rheumatology, 27(5), 601-612. doi: http://dx.doi.org/10.1016/j.berh.2013.10.004

Choi, B. K. L., Verbeek, J. H., Wai-San Tam, W., & Jiang, J. Y. (2010). Exercises for prevention of recurrences of low-back pain. Occupational and Environmental Medicine, 67(11), 795-796. doi:10.1136/oem.2010.059873

Hoy, D., March, L., Brooks, P., Blyth, F., Woolf, A., Bain, C., . . . Buchbinder, R. (2014). The global burden of low back pain: Estimates from the global burden of disease 2010 study. Annals of the Rheumatic Diseases, 73(6), 968-974. doi:10.1136/annrheumdis-2013-204428

Vasseljen, O., Woodhouse, A., Bjorngaard, J.H., & Leivseth, L. (2013). Natural course of acute neck and low back pain in the general population: The HUNT study. Pain, 154(8), 1237-1244.

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Back to basics about psychosocial factors and pain – v


I’ve been writing about psychosocial factors and pain but I realise that I haven’t actually defined what I mean by psychosocial factors. The strange thing about this term is that it’s often conflated with “psychological” or “psychopathological” when it’s actually not. So… where to begin?

The Collins English Dictionary defines psychosocial as: “of or relating to processes or factors that are both social and psychological in origin”, while the Oxford English Dictionary defines it as “Of or relating to the interrelation of social factors and individual thought and behaviour.” According to the Oxford, it first appeared in the American Journal of Psychology in 1890 when it was used to describe the factors associated with the increase of alcoholism. An 1899 journal used it to describe “… psycho-social phenomena, such as language, customs, rights, religion etc., arising from the action of social elements with or upon the individual mind.”

So, the term is fairly recent but seems to have always been associated with broader influences on thoughts and behaviour – that is, a reciprocal response between what individuals think and do, and what helps to shape (and also responds to) what happens in the community.

When we think about pain, the most common “psychosocial” factors seem to be psychological – things like attention (vigilance), catastrophising (thinking the worst), negative affect (low mood), treatment seeking (behaviours associated with looking for help), avoidance (not doing, not approaching). What is lacking in clinical practice, in my humble opinion, is the relationship between how these factors develop and are maintained, and how those around an individual (both family and the wider community) respond to these factors. It’s not that there is no research into these relationships – it’s that research is complex, it’s tough to conduct experiments in this field, and effecting change once relationships are identified is pretty hard. More than that, health professionals typically see individuals, not people-in-context.

BUT here are some of the areas currently being explored.

Clinician behaviour – there would be few readers of this blog who are unfamiliar with Ben Darlow’s work on the power of what clinicians say (Darlow, Dowell, Baxter, Mathieson, Perry & Dean, 2013), though he’s not the first research to begin to look at this – Tamar Pincus and others have also reviewed the influence of practitioners beliefs on what they do for people with persistent pain (Parsons, Harding, Breen, Foster, Pincus, Vogel & Underwood, 2007).  The broad conclusions from this body of work, of which these two are tiny tips of a very large iceberg, is that what clinicians believe about pain and chronicity and hurt/harm influences both their treatment recommendations and their attitude towards people experiencing persistent pain, and has a direct effect on chronicity in the acute stages of a pain problem.

Family responses – Herta Flor and colleagues explored the impact of persistent pain on family relationships way back in the 1980’s, while much more recently,  Burns, Post, Smith, Porter et al (in press) investigated the interaction between spouse criticism and the effect on pain intensity and behaviour in people with persistent low back pain. Chan, Connelly & Wallace (2017) established that poor peer relationships influenced both emotional functioning and persistent pain amongst adolescents, while treatment seeking amongst adolescents was found to be associated with elevated treatment seeking in their parents (Stone & Wilson, 2016). Whether the relationships are genetic (in family patterns of persistent pain and disability), or learned (social learning theory) or a mix of both – it looks like how others respond and behave in relation to pain and disability has a strong influence on persistent pain in an individual.

Work – This, naturally, has been the place of many a study trying to establish a relationship between biomechanical factors and the onset and maintenance of pain, but it has also been the location for studies examining social relationships like supervisory responses, peer relationships, employer flexibility along with the personal effects of workplace stress on the body. I’m not going to review the myriad studies, but point you to a good systematic review of prognostic factors for return to work by Steenstra, Munhall, Irvin, Oranye, Passmore et al (2016) to demonstrate just how many factors have already been identified.

I’ve barely touched the surface of the social aspects influencing our experience of pain and disability. It’s evident that these factors have been identified – but let me ask you this: How often do you identify and then provide an intervention for these social factors? And if not, why not? And if not you – who?

 

Burns, J. W., Post, K. M., Smith, D. A., Porter, L. S., Buvanendran, A., Fras, A. M., & Keefe, F. J. (2017). Spouse criticism and hostility during marital interaction: effects on pain intensity and behaviors among individuals with chronic low back pain. Pain.
Chan, S. F., Connelly, M., & Wallace, D. P. (2017). The Relationship Between Pain Characteristics, Peer Difficulties, and Emotional Functioning Among Adolescents Seeking Treatment for Chronic Pain: A Test of Mediational Models. Journal of Pediatric Psychology, jsx074.
Darlow, B., Dowell, A., Baxter, G. D., Mathieson, F., Perry, M., & Dean, S. (2013). The enduring impact of what clinicians say to people with low back pain. The Annals of Family Medicine, 11(6), 527-534.
Flor, H., Turk, D. C., & Scholz, O. B. (1987). Impact of chronic pain on the spouse: marital, emotional and physical consequences. Journal of psychosomatic research, 31(1), 63-71.
Parsons, S., Harding, G., Breen, A., Foster, N., Pincus, T., Vogel, S., & Underwood, M. (2007). The influence of patients’ and primary care practitioners’ beliefs and expectations about chronic musculoskeletal pain on the process of care: a systematic review of qualitative studies. The Clinical journal of pain, 23(1), 91-98.
Steenstra, I. A., Munhall, C., Irvin, E., Oranye, N., Passmore, S., Van Eerd, D., … & Hogg-Johnson, S. (2016). Systematic review of prognostic factors for return to work in workers with sub acute and chronic low back pain. Journal of occupational rehabilitation, 1-13.
Stone, A. L., & Wilson, A. C. (2016). Transmission of risk from parents with chronic pain to offspring: An integrative conceptual model. Pain, 157(12), 2628-2639.

Back to basics about psychosocial factors and pain – iv


Part of the definition of pain is that it is “a sensory and emotional experience” – in other words, emotions of the negative kind are integral to the experience of pain. Is it any wonder that poets and authors have written so eloquently about the anguish of unrelieved pain? As I write this, I’ve been pondering the way “psychosocial” has been used when discussing pain, as if those factors aren’t experienced by “normal” people, as if the way we feel about pain and the way people who struggle with their pain feel are two entirely different things.

Chris Eccleston, someone I admire very much, writes about a “normal psychology of chronic pain” and makes some incredibly useful points: that pain is a normal feature of human life. Pain is an everyday occurrence (watch kids playing in a playground – every 20 minutes kids communicate about pain, Fearon et al, 1996). In New Zealand one in five people report experiencing pain lasting six months or longer. Pain really is all around us – and it’s normal and indeed part of the experience itself, to feel negative emotions such as fear, anger, sadness, anxiety, and such when we’re sore.

So why have emotions been lumped in with “other factors” as part of the negative way psychosocial factors are interpreted today? I personally think it’s partly a hangover, in NZ at least, from the way our stoic forebears viewed “weakness”. There wouldn’t be many families in New Zealand who haven’t heard something like “man up”, or “big boys don’t cry”, or “pull yourself together” with great All Blacks who played on despite broken ribs or arms – who didn’t give in when they were injured being held up as examples we should emulate. At the same time pain isn’t given much space in our health professional training programmes – and when it is, it’s primarily viewed in a neuroanatomical way, as we’re taught about spino-thalamic tracts, and nociceptors, and not much else. In fact, I think the gate control theory is still being taught as the main theory in some programmes (despite it being revised and replaced with more sophisticated models).

So what is normal? I really like Acceptance and Commitment Therapy, as you’ve possibly noticed. Amongst one of the many reasons I like it so much is its view of suffering. Within ACT, being psychologically inflexible is the problem – that is, working hard to avoid or control experiences we don’t want, getting caught up in thoughts as if they’re Truth instead of our mind’s opinion of things, being attached to someone’s idea of who and what we are, living in the past or predicting the future, and failing as a result to take actions that line up with what our personal values are. When we get stuck thinking there’s only one way to deal with a situation, and when we forget about what’s important in our lives because we’re working so hard to avoid certain experiences – these aren’t seen as pathological, but instead are just part of the way our mind/language and experience tangle us up. The beauty is that there are ways out of being stuck but they’re counter-intuitive.

What do I mean? Well if we all have negative emotions about pain, why do only some of us struggle with that experience and get stuck? For some people it’s because they’re trying so hard not to feel pain that they spend time and energy doing things to control it and in the process stop doing things that matter. Think of the many appointments and the ups and downs of hope that it will all go away with this magic thing – then despair as it doesn’t work. Just the amount of time people spend waiting for and attending appointments can take time away from being with family, working, living…Now to me, this is not psychopathology. This is what normal minds do – try to fix a problem using strategies that have always worked in the past.

At the same time, given pain is a negative experience, doesn’t it make sense to monitor what went on last time you tried to lift that box, go to work, drive the car… AND doesn’t it make sense to anticipate what might go wrong if you try it again? This isn’t about being depressed, anxious or any other kind of pathology – this is just what we’ve learned to do, and our minds are trying incredibly hard to make it work again.

When I mentioned that a solution might be counter-intuitive, what I mean is recognising that trying to control or avoid an experience that comes with us wherever we go because it’s part of us, can trip us up. Instead, we might do better if we soften our attempts to control or avoid our experience of pain. Maybe spending time exploring pain and doing things alongside pain is possible – especially if the things we want to do are important to us. Don’t believe me? Think about marathon runners – they feel the pain (hit the wall) and still keep running! Why? Because it’s important to them to get to the end.

Now I’m not suggesting that ALL people will find this approach helpful, and I’m NOT denying that many people with persistent pain experience depression, anxiety, rotten sleep and generally feel demoralised. What I AM saying is that if we approach everyone with the misguided idea that psychosocial factors exist only in “those people”, we’re wrong. Any one of us will experience negative emotions if pain is present – and even more if pain persists. This is a normal response to a challenging and inherently aversive experience. Of course, if we’ve experienced depression, adverse life events, turmoil in our home and work life, and the stigma of not being believed, the potential to then become angry, depressed, and fed up is only greater. Let’s not make a negative experience worse by stigmatising people with the notion that “psychosocial factors” makes them any different from anyone else.

 

Eccleston, C. (2011). A normal psychology of chronic pain. Psychologist, 24(6), 422-425.

Fearon, I., McGrath, P.J., Achat, H. (1996). ‘Booboos’: The study of everyday pain among young children. Pain, 68, 55-62.

Vowles, K. E., Witkiewitz, K., Levell, J., Sowden, G., & Ashworth, J. (2017). Are reductions in pain intensity and pain-related distress necessary? An analysis of within-treatment change trajectories in relation to improved functioning following interdisciplinary acceptance and commitment therapy for adults with chronic pain. Journal of consulting and clinical psychology, 85(2), 87.

Back to basics about psychosocial factors and pain – iii


Last week I discussed some of the areas in the brain, and basic principles, that are currently thought to influence our pain experience. This week I thought I’d introduce one of my favourite ways of considering pain mechanisms, mainly because it helps me think through the four main kinds of mechanisms, and can influence our treatment approach. At this stage I want to raise my hand to acknowledge the following:

  • My gratitude to Dr John Alchin, longtime friend and colleague, who first pointed this paper out to me and has shared it with hundreds of people who go to see him at the local tertiary pain management centre.
  • We know this is a simplified, under-developed approach to mechanisms underpinning pain, but it’s helpful nevertheless.
  • Most of our patients will have a combination of mechanisms involved in their experience, not just one.
  • This approach to mechanisms doesn’t include the psychological or social – just the primary biological processes.
  • Throughout this blog, when I use the word “pain” I mean the experience we have once whatever mechanisms involved filter up through to our awareness. So while I talk about peripheral mechanisms, they’re only experienced as pain once we become aware of them – and that process involves a whole lot of what I discussed in my last post .

Clifford Woolf wrote this paper in 2010, and although the research into mechanisms has continued unabated, I think it provides clinicians with a reasonable guide to considering how best to tackle treatment. He begins by dividing the mechanisms into “useful” and “useless” pain – ie pain that is useful for adaptation, survival, warning, alerts. Just as it’s possible to have dysfunction or disease of our cardiac, pulmonary, gastro-intestinal, and skeletal systems, I think it’s just as plausible that we can have something go wrong with our nociceptive system. In fact, because of its complexity, it seems probable to me at least that there are many different ways this system can fail to work properly. But more about that shortly! Let’s begin with the useful pain.

Nociceptive pain – is considered to be pain that is, as Woolf puts it, our “early-warning physiological protective system”. When we touch something super cold, super hot, or a chemical that can harm us (think chilli pepper!), or meet a mechanical force that activates mechano receptors, our high threshold nociceptors are activated – well in advance of tissue damage, I quickly add. This process activates withdrawal – even in simple single-celled animals – and saves us from harm. When combined with behavioural responses including vocalisation, grimaces and other pain behaviours, we signal to everyone around us that we’re in danger, and others shouldn’t do what we’ve just done (Melzack, Dennis, Kosterlitz & Terenius, 1980).  For me, the cool thing about nociceptive pain is that once you’ve removed that stimulus (got rid of the chilli on your lips, let go of the ice-cube or the hot mug of coffee, or shifted in your seat to relieve your butt) the pain simply goes away. Just like that. How cool?!

Inflammatory pain – is also a useful pain to have. Unlike nociceptive pain, inflammation involves disruption to the tissues, triggering a release of a whole bunch of neurochemicals and cells that quickly lower the point at which nociceptors will fire (making you much more sensitive to mechanical, chemical and temperature input), and increasing the blood supply to allow foreign material, dead cells and spent neurochemicals to be whisked away. Inflammation is reasonably easy to see in the periphery (though not so easy in the internal organs because the innervation is more diffuse) and you’ll all have had it – think sunburn (I know you’re not meant to, but everyone gets sunburned at least once, especially in our NZ sun). With sunburn you’re red, hot and often swollen, and you really know it when you step into the shower! That experience of ouch! to your usual shower temperature (and the ouch! when you towel down) is allodynia, or the experience of pain when a usually comfortable stimulus is applied. You’ll experience hyperalgesia if your mate comes along and slaps you on your sunburned shoulders!

Now both of these mechanisms are useful because they alert us to threat, they make it more difficult to move around, and we often respond to them with changes in our behaviour that act as a signal to others around us. Let’s turn the attention to two mechanisms where there is something gone awry with the nervous system – in other words, useless pain.

Neuropathic pain – is defined by IASP as “pain caused by a lesion or disease of the somatosensory nervous system.” What this means is that there must be an identifiable lesion in the nervous system somewhere – something that can be imaged or tested to demonstrate damage. This could be in the periphery – think of radial nerve entrapment with its characteristic tingling, deep aching and burning over the distribution of the nerve. It could be in the spinal cord itself – think of a complete spinal cord injury where the person is unable to move from the lesion down, and who also gets the same tingling, aching, burning and electric shock pain over the same area. A simple example would be radicular pain where the nerve root is compressed – and this can be seen on imaging, and where the pain is experienced over the same nerve distribution. The final group in this nasty set of neuropathies is when someone has a stroke, where part of the brain is damaged leading to intractable, deep, aching pain with electric shock-like pain just to make it nastier. For a great paper reviewing neuropathic pain, Finnerup and colleagues wrote one published in 2016 (see below), describing a grading system to indicate possible, probable and confirmed neuropathic pain. The hallmark of this pain is that it doesn’t represent tissue damage except in the area of the nervous system where the lesion is located. In other words, that pain down the leg is not where the problem lies in radicular pain – it’s near the spinal cord. So this pain doesn’t have a function for survival – it’s just a horrid nuisance.

The final mechanism is poorly understood – even less well understood than neuropathic pain. This is where ostensibly the nervous system appears intact. The pain experience might be in multiple parts of the body, it could be just in the head (migraine, for example), or it could be just in the shoulder (frozen shoulder maybe?), or it might be everywhere (fibromyalgia). The name isn’t even completely determined – it’s called “dysfunctional” by Woolf, and he collapsed this and neuropathic pain into one mechanism, but I prefer to keep it separate because it’s more helpful for management especially when a neuropathy might be amenable to surgery. Another term, and one I like, is nociplastic – referring to the idea that it’s the unhelpful neuroplasticity of our nervous system that has over-responded to potential threat (Kosek, Cohen, Baron et al, 2016). Some would argue that this mechanism is partly a general tendency to a lower nociceptive threshold, maybe genetic, maybe behavioural (ie we’ve learned to monitor and respond to threat perhaps because of early life experiences), perhaps a diathesis-stress where the predisposition exists but it’s not brought into expression until a stressor, perhaps a virus or an injury, exerts an influence on homeostasis.

Ultimately, pain is an experience that we’ve all had, and one that has individual meaning for each of us based on our previous experiences, predictions for the future, current goals, culture and biology. What a mechanisms-based approach to pain management might mean is better and more accurate management for each one. So we’d be looking to remove that bunion so people can walk more easily; reduce the inflammation in an auto-immune disease; decompress a squished nerve in neuropathic pain and look to altering plasticity in nociplastic pain. But pain is weird and as I said at the very beginning, it’s entirely possible to have more than one mechanism involved – and because pain is not just biology, we’d be foolhardy to think that just by down-tuning the intensity, everyone so treated will go “back to normal”. More on that next week!

 

 

Finnerup NB, Haroutounian S, Kamerman P, et al. Neuropathic pain: an updated grading system for research and clinical practice. Pain. 2016;157(8):1599-1606. doi:10.1097/j.pain.0000000000000492.
Kosek, E., Cohen, M., Baron, R., Gebhart, G. F., Mico, J. A., Rice, A. S., … & Sluka, A. K. (2016). Do we need a third mechanistic descriptor for chronic pain states?. Pain, 157(7), 1382-1386.

Melzack, R., Dennis, S. G., Kosterlitz, H. W., & Terenius, L. Y. (1980). Phylogenetic evolution of pain-expression in animals. Pain and Society, 13-26.

Woolf CJ. What is this thing called pain? The Journal of Clinical Investigation. 2010;120(11):3742-3744. doi:10.1172/JCI45178.

Back to basics about psychosocial factors and pain (ii)


But what about the bio? No, not the biographical, the biological! It’s something I often get asked – like “if you think pain is psychological/psychosocial factors play a part then you’re obviously not including the biological” – oh woe is me, for no, pain definitely involves the biological. But it’s not quite as simple as we’ve come to believe.

Let’s begin at the very beginning. Can we have pain – and not know about it?

The answer is – no, and that’s exactly why anaesthetics are used. The distinction between pain and nociception is that it’s entirely possible for nociception to be occurring all the time, even while unconscious, whereas pain can only be experienced by a conscious person. What this means is nociception is about activity in the nociceptive system right up until the point at which we become conscious of it. And the point at which we become conscious of the ouch shifts depending on a bunch of things, one of which is how much attention we have available, our current goals, whether we’ve had this experience before, what we think the experience is about, and what we’ve learned about this experience from our community.

So, I’m going to discuss pain biology from the brain down instead of nociceptive fibres because our brains are not just blank pages waiting for information to hit it – but actively filter, select and augment information to (a) keep us alive and safe, and (b) help us reach our goals. Louis Gifford put this nicely – our brain is sampling from our context, cognitive set, mood, chemical and structural inputs (neurodegeneration, metabolic changes and plasticity) as well as our current sensory input (which is the bit we usually start from). What the brain then does is generate outputs – the experience of pain, movements, immune response, endocrine responses, and what goes on in our somatosensory system (Gifford, 1998).

What parts of the brain are active when we feel pain?

Well, there are at least three parallel cortical processes – one is essentially about where we hurt and involves the S1 or somatosensory cortex, the parietal operculum, the cingulate cortex and the posterior insula. The second is about attention or salience and involves the anterior cingulate cortex, the amygdala and the anterior insula. The third is about generating and integrating a behavioural response – and involves the frontal cortex (orbitofrontal, anterolateral and prefrontal), the middle cingulate cortex, and the posterior cingulate cortex. (Fenton, Shih, & Zoltan, 2015).

Now before I go any further, I want to point out that our understanding of these networks is based on various brain imaging studies – and brain imaging studies do not show the “what it is like” to experience pain. Our understanding is incomplete still because imaging technology is still evolving (see Borsook, Sava & Becerra (2010) for more information). But it is from the studies that we begin to  get an understanding of the complexity of the processes and networks involved in producing our experience – no wonder some feel overwhelmed by the sheer volume of information we could explore when trying to understand pain! Especially if our focus has traditionally been on peripheral to spinal nociceptive processing – by the time we get to the brain we’re overloaded and it just seems a bit hard to comprehend.

When we investigate what Melzack calls the “neuromatrix” we need to remember that our understanding is incomplete. What we do know is there is no “pain matrix” but instead there is a salience matrix where simultaneous processing across multiple locations in the brain occur. These locations include areas generally associated with emotions, areas associated with cognitions, and with location and response generation. And importantly, there is never a time when these areas are completely inactive – there is constant activity throughout the networks, meaning that when a stimulus arrives from the periphery, it arrives into an active “salience” network – always determining the question “compared with what is happening right now (goals and alertness) how dangerous/important is this really?”

For a lovely image showing the various areas of the brain involved in processing this experience – click here for the full article – take a look at this image from Denk, McMahon & Tracey (2014)

Now if you’re wondering why I haven’t covered the brainstem and spinal cord etc – do not worry, these will be coming soon! But I won’t be discussing nociception because this is usually discussed in undergraduate training and is often the focus and only aspect of pain covered!

Next time – delving into mechanisms!

What are the implications of the complexity of central processing?

  1. The brain is not simply waiting for information – it actively seeks information relevant to survival
  2. Psychological processes such as attention, emotion and decision-making are biological
  3. The point at which we become aware of pain shifts depending on inputs (bottom up) as well as salience, emotions and consciousness (top down) and contextual factors including what we learn from our socio-cultural environment

And what this means is that psychosocial factors are integral to a biopsychosocial framework for understanding pain. In other words – it is not possible to divide the experience of pain into biological, psychological or social only, except for teaching/learning purposes.

 

 

Borsook, D., Sava, S., & Becerra, L. (2010). The pain imaging revolution: advancing pain into the 21st century. Neuroscientist, 16(2), 171-185. doi:10.1177/1073858409349902

Denk, F., McMahon, S. B., & Tracey, I. (2014). Pain vulnerability: A neurobiological perspective. Nat Neurosci, 17(2), 192-200. doi:10.1038/nn.3628

Fenton, B. W., Shih, E., & Zolton, J. (2015). The neurobiology of pain perception in normal and persistent pain. Pain Management, 5(4), 297-317.

Gifford, L. (1998). Pain, the Tissues and the Nervous System: A conceptual model. Physiotherapy, 84(1), 27-36. doi:10.1016/S0031-9406(05)65900-7

Back to basics about psychosocial factors in pain (i)


From time to time I see a flurry of tweets or Facebook posts about pain and psychosocial factors. Many of them are informative, intriguing and empathic, but some are just plain wrong. The ones I most get upset about are those arguing that because someone has “psychosocial factors” their pain must be psychological in origin, followed closely by the idea that psychosocial factors equate to psychopathology. This is a series of back to basics posts where I hope to set these things right.

Pain, according to the current definition, is

“an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage”[7] is derived from a 1964 definition by Harold Merskey,[8] and it was first published in 1979 by IASP in PAIN, number 6, page 250.

An associated note, which should be read alongside this definition is:

Note: The inability to communicate verbally does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment. Pain is always subjective. Each individual learns the application of the word through experiences related to injury in early life. Biologists recognize that those stimuli which cause pain are liable to damage tissue. Accordingly, pain is that experience we associate with actual or potential tissue damage. It is unquestionably a sensation in a part or parts of the body, but it is also always unpleasant and therefore also an emotional experience. Experiences which resemble pain but are not unpleasant, e.g., pricking, should not be called pain. Unpleasant abnormal experiences (dysesthesias) may also be pain but are not necessarily so because, subjectively, they may not have the usual sensory qualities of pain. Many people report pain in the absence of tissue damage or any likely pathophysiological cause; usually this happens for psychological reasons. There is usually no way to distinguish their experience from that due to tissue damage if we take the subjective report. If they regard their experience as pain, and if they report it in the same ways as pain caused by tissue damage, it should be accepted as pain. This definition avoids tying pain to the stimulus. Activity induced in the nociceptor and nociceptive pathways by a noxious stimulus is not pain, which is always a psychological state, even though we may well appreciate that pain most often has a proximate physical cause.

The final sentence in the note is important, distinguishing between the experience of pain and the biological apparatus transmitting information from the nociceptors, ending in a bunch of places in the brain. I personally dispute the sentence “many people report pain in the absence of tissue damage or any likely pathophysiological cause; usually this happens for psychological reasons” because (recall when it was first written) science has moved on and we now have good evidence supporting the notion that abnormal processing is involved in cases such as migraine (Iyengar, Ossipov & Johnson, 2017; Pietrobon, 2017) and fibromyalgia (Schmidt-Wilcke & Diers, 2017; Tour, Lofgren, Mannerkorpi, Gerdle, Larsson, Palstam et al, 2017). As a side note, I love science because we can revisit beliefs and revise our understanding as more information is collected – whether we’ll ever get to the “truth” is debatable, but we can get closer and closer as we continue learning (see Bhaskar).

Back to basics. It’s evident that ALL pain is a psychological experience and therefore will be influenced by our current goals, past experiences and predictions for the future. And these aspects of attention, motivation, memory and decision-making are present in all of us and for every sensory experience. Take sound, for example. I’m sitting at home listening to a large truck rumbling away, dumping construction materials in the section two doors down. That sound is so like the deep rumble and thud of an earthquake that I’m aware I’m on edge because, after more than 10,000 earthquakes since the first one in the Canterbury region this day seven years ago, my nervous system has learned to be on high alert – who knows what could happen next?

Seven years of learning, 10,000 earthquakes-worth of learning, lots of emotions and lots of very real and scary outcomes. It affects people. In the same way, pain, which we learn about from birth, is influenced by personal experience, by other people’s experiences, and by prevailing community attitudes. This is not psychopathology – at least, not for me though some people have experienced PTSD as a result of the earthquakes we’ve been through. You’d likely do that if you were trapped in a building with no way out, and countless aftershocks continuing while rescuers try to get to you. Most people in Christchurch, however, have simply learned to be aware of sights and sounds that signal a quake – and quickly get back to usual once the sounds have gone. Similarly, most people who experience pain, don’t have a mental health problem – they’ve learned, as we all do, that pain is unpleasant, and learn to avoid situations where pain is likely to occur. In our society, experiencing pain is not viewed as “normal” and indeed, some people have called us “algophobic” – afraid of pain (Kugelmann, 2016). This means we’ve learned to look for ways to get rid of our pain, even if it’s not very intense – because pain means something is “not right” with us.

And one of the functions of pain is to alert us to the potential that something is threatening our bodily integrity, and withdraw or avoid such situations (ie, to learn from them). And as a species we’re designed to be social, so we also display behaviour when we’re hurt that others can see – thus helping spread the word “don’t do that dumb thing!” (Steinkopf, 2016).

To summarise: pain is an experience we’ve all had, and yet it remains something we don’t fully understand. Irrespective of the modality of sensory experience, humans are hard-wired to make sense of, and act upon, experiences based on prior learning, current goals and future predictions, within a context that is inherently social. We’re actively engaged in making sense of our experiences so we can remain safe and give and receive support from those around us. While the experience is psychological, the apparatus producing that experience is biological, filtered through our social and contextual experiences. Like taste, sound, and colour – pain is inherently subjective.

Next post – does this mean the biological is redundant?

Iyengar, S., Ossipov, M. H., & Johnson, K. W. (2017). The role of calcitonin gene–related peptide in peripheral and central pain mechanisms including migraine. Pain, 158(4), 543.
Kugelmann, R. (2016). Constructing Pain: Historical, psychological and critical perspectives. Taylor & Francis.
Pietrobon, D. (2017). Lessons from familial hemiplegic migraine and cortical spreading depression. Neurobiological Basis of Migraine.
Schmidt-Wilcke, T., & Diers, M. (2017). New Insights into the Pathophysiology and Treatment of Fibromyalgia. Biomedicines, 5(2), 22.
Steinkopf, L. (2016). An evolutionary perspective on pain communication. Evolutionary Psychology, 14(2), 1474704916653964. doi:doi:10.1177/1474704916653964
Tour, J., Löfgren, M., Mannerkorpi, K., Gerdle, B., Larsson, A., Palstam, A., … & Schalling, M. (2017). Gene-to-gene interactions regulate endogenous pain modulation in fibromyalgia patients and healthy controls—antagonistic effects between opioid and serotonin-related genes. Pain, 158(7), 1194.

Knee pain – and central sensitisation


Last week I started to discuss central sensitisation indicators in people with osteoarthritic knees, based on a paper by Lluch, Nijs, Courtney, Rebbeck, Wylde & Baert, et al (2017). I’m going to continue with this topic this week, because with the rise of osteoarthritis in the general population and particularly the impact of an aging population, I think we will all need to think hard about how we conceptualise osteoarthritis, and what we do for management. While efforts within my own Department (CReaTE – tissue engineering) involve developing new ways to remodel knee-joint tissues, we know that it will be some years before this approach is widely available (human trials haven’t started yet), and given the relative lack of funding for joint replacements, I think developing effective assessment and rehabilitation for painful knees is a real area of development.

So last week I discussed using simple measures such as >5 on a 0 – 10 VAS (NRS), pain drawings/maps showing radiating pain or widely distributed pain, the pattern of pain fluctuation (during activity, with an increase after activity), and using a couple of fairly simple questionnaires to help identify those most likely experiencing more than the “simple” OA pain we’ve learned about. And as always, identifying psychosocial factors which can lead to increased disability and distress is important.

Along with the clinical interview, we usually incorporate physical examination or physical performance testing. There are some indicators that might be useful such as inconsistent responses to our usual physical examination (ie testing increases pain even though some of them shouldn’t do so) – this should not be interpreted as a sign that the person is “faking bad” or exaggerating their experience. I can’t emphasise this enough! It’s possible that anxiety on the part of a person can wind the nervous system up – leading to what is usually non-nociceptive input being interpreted as nociceptive (Courtney, Kavchak, Lowry et al, 2010).

Another indicator is the presence of widespread hypersensitivity to mechanical stimuli – it’s a common finding in people who have central sensitisation and includes increased response to pressure and touch. You could, as a clinician, use a pressure algometer both close to the knee, and further away, to establish over-excitability of the nociceptive pathways. Interpreting findings using pressure algometry is not straightforward because there is overlap between those with OA and those without, but it’s possible to use norms from the general population (such as Nesiri, Scaramozzino, Andersen et al, 2011). It’s a bit of a challenge because of the overlap between the two populations, but can add to the clinical picture. Pain (allodynia) on light touch or being stroked with a cottonwool ball around the knee, is definitely a clue that something’s up.

Both thermal hyperalgesia and tactile hypoaesthesia (reduced sensitivity to von Frey fibre testing) have been associated with central sensitisation – if you don’t have formal testing apparatus, the back of a warmed teaspoon placed on the skin for 10 seconds should be experienced as hot but not painful in someone who isn’t tending to central sensitisation, and you can use cottonbuds (or cottonwool) to identify loss of sensation acuity, provided you do so in a systematic way (the authors suggest starting where it’s most painful and stimulating the skin in a wheel spoke pattern, gradually widening out).

Putting it all together

Any single test, on its own, is unlikely to be a good predictor of central sensitisation, but when combined with the information you obtain from the person, along with the relevant questionnaires, should begin to help develop a picture of who is likely to have a less-than-ideal response to planned trauma. What we do about reducing the potential for central sensitisation is still  begin hotly debated but we DO know that giving good information about pain mechanisms, and encouraging graded exposure and graded activity can be helpful. Given that exercise is a good approach for reducing the impact of osteoarthritis in the knee, for those with the additional burden of central sensitisation, I think swimming or hydrotherapy could also be helpful, as could mindfulness and even mindful movement like tai chi, yoga or xi gong.

Conclusion

People living with OA in their knees often spend many years having difficulty managing their pain before they are able to have surgery. From recent research in New Zealand, I don’t think many people are offered a pain “education” approach, and indeed, I’d bet there are a lot of people who don’t get referred for movement-based therapy either. Misunderstanding is rife in OA, with some people uncertain of the difference between osteoarthritis and rheumatoid arthritis, and others very worried that they’re going to “wear the joint out” if they exercise. While OA isn’t as sexy as low back pain, doesn’t have the economic cost of low back pain, and has a reasonable surgical option – it is still a significant problem for many people. Helping those people be more confident to move, helping reduce their uncertainty about the effect of movement on their joints, and giving them an opportunity to think differently about their knee pain would be a real step forward. Surgery, while helpful for many, is either not available or unsuccessful for others, and it’s time we attended to their needs as well.

 

Courtney CA, Kavchak AE, Lowry CD, et al. (2010). Interpreting joint pain: quantitative sensory testing in musculoskeletal management. Journal of Orthopaedic Sports Physical Therapy. 40:818–825.

Lluch Girbes E, Meeus M, Baert I, et al. (2015) Balancing “hands-on” with “hands-off” physical therapy interventions for the treatment of central sensitization pain in osteoarthritis. Manual Therapy. 20:349–352.

Lluch, E., Nijs, J., Courtney, C. A., Rebbeck, T., Wylde, V., Baert, I., . . . Skou, S. T. (2017). Clinical descriptors for the recognition of central sensitization pain in patients with knee osteoarthritis. Disability and Rehabilitation, 1-10. doi:10.1080/09638288.2017.1358770

Neziri AY, Scaramozzino P, Andersen OK, et al. (2011). Reference values of mechanical and thermal pain tests in a pain-free population. European Journal of Pain. 15:376–383.

Knee pain – not just a simple case of osteoarthritis


Knee osteoarthritis is, like so many chronic pain problems, a bit of a weird one. While most of us learned that osteoarthritis is a fairly benign disease, one that we can’t do a whole lot about but one that plagues many of us, the disability associated with a painful knee is pretty high – and we still don’t have much of a clue about how the pain we experience is actually generated.  Cartilage doesn’t have nociceptive fibres, yet deterioration of cartilage is the hallmark of osteoarthritis, though there are other structures capable of producing nociceptive input around the knee joint. Perhaps, as some authors argue, knee osteoarthritis is a “whole organ disease with a complex and multifactorial pathophysiology involving structural, psychosocial and neurophysiological factors” (Arendt-Nielsen, Skou, Nielsen et al, 2015).

Central sensitisation, or the process in which spinal cord and the brain become “wound up” or more responsive to input than normal, and seems to be a factor in the pain some people experience when they have osteoarthritic knees (Fingleton, Smart, Moloney et al, 2015; Finan, Buenaver, Bounds, Hussain, Park, Haque et al, 2013), particularly in women (Bartley, King, Sibille, et al, 2016). The problem is, few people are routinely screened for central sensitisation before they receive surgical treatment (a good question is whether pain-related research is a factor in orthopaedic assessment). Why should we think about screening? Well, outcomes for joint replacements in knee OA are not as good as they are for hip OA, and a good proportion of people have more than one surgery to attempt to revise the joint but ultimately don’t obtain a satisfactory resolution of their pain.

The authors of this very useful clinically-relevant paper “Clinical descriptors for the recognition of central sensitization pain in patients with knee osteoarthritis” (Lluch, Nijs, Courtney, Rebbeck, Wylde, Baert, Wideman, Howells and Skou, 2017) openly acknowledge that although the idea of central sensitisation in humans is appealing, and seems to answer a number of important questions, the actual term “central sensitisation” can, at this time, only be measured in animal models. The use of the term in humans is not yet agreed upon, and a term I find appealing is “nociplastic”, or in other words, plasticity of the nervous system underpinning an increase in responsiveness to “actual or potential tissue damage” (to quote from the IASP definition of pain). They argue that central sensitisation may not exist in a dichotomous “yes you have it” or “no you don’t”, but instead may from a continuum from a lot to a little, and they note that pain sensitivity also exists on a continuum (a bell-shaped curve).

So what’s a good clinician to do? We can’t all go out and get involved in conditioned pain modulation or in using brain imaging, yet it seems important to establish who might respond well to joint replacement vs who might need additional input so they get a good outcome. And something that’s not going to add too much expense or complexity to an assessment process that, at least in New Zealand, is rationed because of cost. (oops, sorry not “rationed” just “waitlist management”).

The first step as described by Lluch and colleagues involves the “subjective” assessment – I loathe the word “subjective” because this is the person’s own experience, and doesn’t need to be tainted with any suggestion that it’s inaccurate or can’t be trusted. ‘Nuff said. During an interview portion of an assessment, the authors suggest using some simple measures: reports of pain above 5/10 on a numeric rating scale where 0 – no pain, 10 – extreme pain. They add increased weight to this report if there is little significant found on simple imaging of the knee, because central sensitisation is thought to be less relevant where there is severe structural changes in the knee joint.

A pain drawing can be helpful – radiating pain, pain on the contralateral leg, and pain in other body sites can be an indication of central sensitisation, while pain that is localised just to the joint itself may be an indication that a surgical approach will be more likely to help. Using the Widespread Pain Index score >7 and painDETECT score >19 (seeVisser, et al, 2016) may be a relatively simple process for clinicians to use to identify those with troublesome pain.

The behaviour of pain with/without movement may be a useful indicator: those that find movement painful, or who report increased pain after engaging in physical activity might be responding to central sensitisation, given that OA pain is usually associated with rest. Add to this a discussion about what relieves the pain and what doesn’t (where easing up on mechanical demands should reduce pain while with central sensitisation, this may not occur), and those with pain that continues after movement may need more help with central sensitisation than those who don’t.

The authors also suggest two questionnaires that may help to spot the person experiencing central sensitisation – the painDETECT or the Central Sensitisation Inventory. At this point I’m not entirely certain that the CSI measures only central sensitisation (it may simply measure somatic attention, or distress), so I’d interpret the findings carefully and make sure the clinical picture confirms or doesn’t… while the painDETECT has been used to identify those with neuropathic pain, and may be appropriate though it hasn’t been strongly confirmed for use with knee OA (it was developed for low back pain). While you’re at it, you should also assess for psychosocial factors such as the tendency to think the worse, low mood, feeling helpless, and perhaps factors such as not liking your job, having limited family support, and maybe self-medicating with alcohol and tobacco or other substances.

Finally, for today’s post (yes I’ll carry on to the clinical tests next week!), response to pharmacology may also be a useful approach to identifying those with central sensitisation. Poor response to NSAIDs (the mainstay for knee OA in NZ), weak opioids (like codeine), and perhaps not responding to things like heat or joint mobilisation, may also be useful predictors.

In summary, there are numerous indicators one can use to help establish who might not respond well to a peripheral-only treatment. While some of these measures are used routinely by enlightened clinicians, there are plenty of people who think of these responses as an indication of “poor coping” or someone who REALLY needs surgery. Unless surgeons and those who work with people with knee OA begin to examine the literature on pain in knee OA, I think we’ll continue to have patients who receive surgery when perhaps it’s not the best thing for them. More on this next week.

 

 

 

Arendt-Nielsen L, Skou ST, Nielsen TA, et al. (2015). Altered central sensitization and pain modulation in the CNS in chronic joint pain. Current Osteoporosis Reports, 13:225–234.

Bartley EJ, King CD, Sibille KT, et al. (2016) Enhanced pain sensitivity among individuals with symptomatic knee osteoarthritis: potential sex differences in central sensitization. Arthritis Care Research (Hoboken). ;68:472–480.

Finan PH, Buenaver LF, Bounds SC, Hussain S, Park RJ, Haque UJ, et al. (2013). Discordance between pain and radiographic severity in knee osteoarthritis: findings from quantitative sensory testing of central sensitization.  Arthritis & Rheumatism, 65, 363-72. doi:10.1002/art.34646

Fingleton C, Smart K, Moloney N, et al. (2015). Pain sensitization in people with knee osteoarthritis: a systematic review and meta-analysis. Osteoarthritis and Cartilage, 23:1043–1056.

Kim SH, Yoon KB, Yoon DM, Yoo JH & Ahn KR. (2015). Influence of Centrally Mediated Symptoms on Postoperative Pain in Osteoarthritis Patients Undergoing Total Knee Arthroplasty: A Prospective Observational Evaluation.  Pain Practice, 15, E46-53. doi:10.1111/papr.12311

Lluch, E., Nijs, J., Courtney, C. A., Rebbeck, T., Wylde, V., Baert, I., . . . Skou, S. T. (2017). Clinical descriptors for the recognition of central sensitization pain in patients with knee osteoarthritis. Disability and Rehabilitation, 1-10. doi:10.1080/09638288.2017.1358770

Visser EJ, Ramachenderan J, Davies SJ, et al. (2016). Chronic widespread pain drawn on a body diagram is a screening tool for increased pain sensitization, psycho-social load, and utilization of pain management strategies. Pain Practice, 16, 31-37

Conversations about cannabis for chronic pain


The debate about cannabis and derivatives for persistent pain continues to grow in New Zealand, and elsewhere in the world. Many people I’ve treated and who are living with persistent pain say they like to use cannabis (in a variety of forms) to help with pain intensity and sleep, adding their voices to those wanting “medicinal” cannabis to be approved. In the few patients I’ve worked with who have managed to obtain a cannabis product (in NZ it has to be legally prescribed and will generally be in the form of Sativex or similar) the effect doesn’t seem as profound as the real thing (whether smoked, vaped, or in edibles).

Here’s my current position, for what it’s worth. Right now I think cannabis legislation needs an overhaul. Cannabis doesn’t seem to fit into the same class as synthetic drugs (often called “herbal highs” or synthetic “cannabis”) – for one, the plant probably contains a whole lot of substances that have yet to be fully analysed, and for another, I have yet to see a death reported from cannabis use, yet in Auckland, NZ, alone this year there have been around 9 people who have died from taking the synthetic substance, whatever it is. Cannabis seems to cause less harm than legal substances like alcohol and tobacco, and in many places in the world it’s been legalised with some interesting effects on use of opioids.

Ever since Professor David Nutt visited New Zealand a few years back, I’ve been convinced it’s time for a rethink on cannabis laws, but at the same time I’m not ready to support wholesale legalisation of “medical” marijuana. Here are a few reasons why:

  • When a doctor prescribes a drug, he or she is able to rely on the manufacturer making a consistent product, with a consistent amount of “active” ingredients, and a consistent quality. At present, with the exception of the two versions available in New Zealand, this can’t be guaranteed. Plants vary in the combination of active chemicals in them, and storage and age of the product influence the availability of those chemicals when inhaled or ingested. Just as we don’t suggest people go and grow their own opium poppies because we know that opioids are effective analgesics, I don’t think it’s time to allow people to grow their own cannabis for medicinal purposes, such as treating pain. A doctor can’t know just how much of a dose a person can get because in NZ we don’t yet have a controlled environment for cannabis production.
  • When a doctor prescribes a drug, he or she is also guided by the indications for use. So, although some medical practitioners prescribe “off-label” use for medications (a good example is nortriptyline, an antidepressant used often for pain reduction), generally there are good double-blinded, randomised controlled trials to determine whether the active drug is more effective than placebo. When we read about cannabis use for medicinal reasons we hear of its use for cancer (mainly nausea, but also pain), neuropathic pain, and in the general media we hear of its use for migraine, period pain, abdominal pain, fibromyalgia, osteoarthritis – there’s very few pain disorders that cannabis isn’t seen to be appropriate. But the truth is, we don’t really know which kind of pain (the underlying mechanism) will respond, and what pains don’t respond. It’s still a bit of a mystery – mind you, this is not any different from other medications for pain for which N=1 seems to be the mantra.

Why might I support a change to marijuana laws?

Well, an interesting study from the Northeastern United States, and published in the journal Pain, looked at the perspectives of people enrolled in legal medical marijuana clinics. It was quite a large study of 984 people, so should represent a good cross-section of those using the drug within a legal system. Participants were asked to complete an online survey, and their responses were analysed by a psychologist who was “not a cannabinoid expert”, arranging the data into themes and subthemes. (As an aside, apparently this was carried out using a “Grounded Theory perspective” based on Corbin and Strauss – BUT essentially the researchers didn’t follow grounded theory methodology throughout, and instead it should be called a thematic analysis using inductive coding. Pedant, yes!). The data was then examined to quantify the responses (another violation of GT methodology), and re-examined by another co-author for verification.

What they found was a group of people, over half women, with 2/3 indicating they’d been diagnosed with chronic pain by a medical professional. Diagnoses varied, but most (91%) had low back and neck pain, 30% with neuropathic pain, 23% with postsurgical pain, nearly 22% with abdominal pain, 20% with chronic pain after trauma/injury, 7% with cancer pain and 5% with menstrual pain.  Most people smoked cannabis either by joint, pipe or bong; some used a vaporiser, some had edibles or a tincture, and least, some sort of ointment.

The participants indicated it was on average 75% effective at reducing/treating symptoms, which is extraordinary when you realise that traditional forms of medication for neuropathic pain may reduce pain by 50% in around 1  in 4 people (Woolf, 2010). Participants spent around $3118 each year, but this was skewed because concentrates cost $3910, while topicals were $814. Joints were more expensive than vaporised product ($260 different!).

Analysing the positives of cannabis, participants reported pain relief, or at least being able to tolerate the pain more easily; while sleep benefits was the next most significant theme. Participants were encouraged that cannabis doesn’t have overdose potential, it’s natural, there are a wide range of strains with different characteristics, and limited potential for dependence.

There were numerous other positive aspects to using cannabis this way, according to the participants: things like “feeling normal”, “I am more active and able to do things I want”, being “distracted” from the pain, “able to focus”, and “able to relax”.

Negative perspectives included the cost (too expensive – in NZ Sativex is around $1000 a month – not covered by NZ pharmaceutical subsidies); some people didn’t like the smell, the effects on lungs and breathing, appetite changes (and gaining weight), and some emotional effects like anxiety or paranoia. Stigma and judgement by others also features, as did the difficulty accessing the drug, and conflict about the different laws applying to cannabis use – noting that the US has different federal and state laws.

Overall, the responses from these participants suggest a benign, mainly positive response to a drug, with negatives primarily around the social aspects – stigma from health providers, other people thinking of the participants as stoners, the legal situation and so on. For me, the limitations of this study really preclude any major judgement as to benefit or otherwise. We only know what this group of people believed, they have a vested interest in promoting benefits because negatives won’t support their belief that this is a viable treatment option, we don’t know the effect on function (particularly objective data), and we have no way of verifying the diagnoses individuals reported as the reason for prescription.

My conclusion?

It’s way past time to discuss cannabis use, health risks and health benefits. To have an open discussion about use for medicinal reasons, we need to remove the current barrier: the legal situation. While people have a vested interest in promoting the benefits over risks or adverse effects, we’re not going to have a very clear picture of what happens with ongoing use. I don’t support the use of cannabis as a medicinal product – to me there are far too many unknowns, and I think we risk wedging open a gate that has, until now, been useful for limiting the risk from pharmaceutical harms. We need to subject cannabis to the same level of rigour as any other pharmaceutical product being introduced to the market.

On the other hand, I think removing legal barriers to recreational use is about balancing the benefits and harms of this substance against other substances used for similar reasons. Alcohol and tobacco are well-known for harmful effects. Prohibition of alcohol did not work. Tobacco smoking is reducing over time courtesy of a committed campaign documenting harms, as well as raising the price via taxation. We can’t campaign around health harms for a product that isn’t legal. We can’t establish useful regulation over who produces it, who can buy it, where it can be used, the effects on work injury/vehicle injury, we can’t represent the undoubted benefits, and we look, to many people, to hold a double-standard.

And sneaking cannabis use in under the guise of “medicinal” use just isn’t on, in my humble opinion. Let’s not put medical practitioners in an unenviable situation where they’re asked to prescribe a product that is not yet examined to the level we expect for every other pharmaceutical product on the market. Let’s spend some precious research funding to establish WHO cannabis helps, WHAT it helps with, and HOW it helps – and most importantly, let’s look at whether it helps produce outcomes that surpass other approaches to persistent pain. We need to face it, currently our treatments are not very good.

 

Piper, B. J., Beals, M. L., Abess, A. T., Nichols, S. D., Martin, M. W., Cobb, C. M., & DeKeuster, R. M. (2017). Chronic pain patients’ perspectives of medical cannabis. Pain, 158(7), 1373-1379.

Woolf, C: (2010). Review: Overcoming obstacles to developing new analgesics, Nature Medicine (Supplement); 16,11: 1241 – 47

Great expectations – and low back pain


Have you ever wondered why there are so many treatments for low back pain? Like there are actually hundreds of different ways to “treat” back pain… yet the truth is, none of them work for everyone. Actually, most of them seem to help pass the time until low back pain settles of its own accord. Until it’s back again (no pun intended!).

This post is prompted after reading a string of general news articles discussing the common non-specific low back pain – under various guises of “dead butt syndrome“, “Dr Tom: Ouch I’ve hurt my back” and the like – I think it’s time for a frank discussion about the natural history of low back pain, as found in large epidemiological studies. There’s no doubt that low back pain is a problem around the world, and I think it’s partly due to unmet expectations (along with a whole lot of other variables). The Global Burden of Disease found low back pain to be the most common reason for days lived with disability around the world – that’s more than anaemia, depression, hearing loss, migraine!

Low back pain is common in every single country in the world.

Dunn, Hestbaek & Cassidy (2013) examined the prevalence of low back pain across the life span – they found that many of us view low back pain as a simple “yes/no” question – do you have it, or don’t you. They point out that people with no back pain at the time of a survey are not all the same: some might never have had a bout ever, while some might have had several bouts but just don’t have one right now. These presentations are not the same! Those who have had a previous episode will have developed an understanding of back pain on the basis of what happened, and this will influence their expectations, and subsequent response, to treatments.

Dunn, Hestbaek & Cassidy found that children/adolescents have a point prevalence (ie at the time of the survey, they reported they had back pain) of 12%. As people get older the prevalence continues to be around 12%. The elderly, those over 60 (that doesn’t really feel old to me!), seem to have a prevalence similar to people in middle age, and activities affected by low back pain seem to increase as we age.

Given the lifetime prevalence of low back pain is around 80% (or more), following people up over time seems to paint a different picture from the point prevalence studies: it’s not the same 12% of people that has low back pain all the time. Some studies show that at least 40% of people do recover within a year of an episode (see Hestbaek, Leboeuf-Yde, & Manniche, 2003). A Danish study with 5 year follow-up found around 23% of people consistently reported no pain days during the previous year (during the study) but around 10% reported more than 30 days of back pain every time they were asked. So, while long-term low back pain isn’t common in the adult population, most people do have a couple of bouts over long periods of time.

What are the risk factors? Well one clear risk factor is having had a previous episode, although this isn’t a consistent predictor for long-term back pain. Perhaps we should take a look more closely at the natural course of acute neck and low back pain – from the Norwegian longitudinal studies. From one city in Norway, these researchers screened 9056 people between 20 – 67 years old to identify those with a brand new bout of neck or back pain in the previous month – 219 people were identified, then followed for 12 months. What these researchers found was pain decreasing rapidly in the first month, irrespective of treatment, thereafter though, back pain didn’t change for the rest of the year especially for those with pain in the neck as well as the back at the first assessment, and for those who had 4 or more pain sites in the beginning.

Now what’s really interesting about this study is that the pain reduction people experienced, particularly in low back pain, was pretty close to the pain reduction people achieved whether they had treatment, or not. Hmmmm. Next question: what if we look at all the treatments people get, and those who are in the control group, and pooled that information to find out what happens? Artus, van der Windt, Jordan & Croft examined whether just taking part in a study on low back pain might influence outcomes – so they pooled 70 RCTs and 19 cohort studies, and both sets of data showed “a rapid improvement in the first six weeks followed by a smaller further improvement until 52 weeks. there was no statistically significant different in pooled standardised mean change (a measure used to compared the pooled within-group change in pain in RCTs with cohort studies) – get this, at any time point.

But wait, there’s more!

Axen & Leboeuf-Yde (2013) looked at the trajectories of low back pain over time. They summarised four studies in primary care or the general population, finding that over the course of between 12 weeks and 12 months, participants could be divided into two to four groups: one group remained uncomfortable, perhaps staying that way over the whole 12 months (around 10 – 21%); one group also remained uncomfortable but they reported their pain as “moderate” or “mild” – around 36%; another approximately 30% experienced fluctuating or intermittent low back pain; and finally, the group we love – those who recovered and remained that way, around 30 – 58%.

This is not the picture we hear in the media. This is not what we were taught. And yes, I know there are problems with pooled data because individualised responses get ironed out. But what all this says to me is – our patients come to us expecting that low back pain should completely resolve. The reality is that for a lot of people, back pain will come and go throughout the lifetime.

What does this mean to me?

Isn’t it time to give people an idea that if they have a bout of back pain, chances are high they’ll have another. Complete resolution of low back pain may not occur for a large number of people. A new bout of low back pain may not mean a new “injury” (given we don’t know why many people develop back pain in the first place). Learning to self-manage a bout of back pain is likely to save people a load of heartache, not to mention a lot of money. And maybe it’s the latter that means it’s very hard to find clear, effective messages about just how safe a painful back is. It’s far easier to sell a message of vulnerability, of the need for treatment for that “unhappy spine” as a chiropractor in Christchurch calls it. And of course, if we continue to allow the expectation that all pain should be gone, we’re going to be in business for a very long time…

 

Artus, M., van der Windt, D., Jordan, K.P., & Croft, P.R. (2014). The clinical course of low back pain: A meta-analysis comparing outcomes in randomised clinical trials (rcts) and observational studies. BMC Musculoskeletal Disorders, 15, 68.

Axén, I., & Leboeuf-Yde, C. (2013). Trajectories of low back pain. Best Practice & Research Clinical Rheumatology, 27(5), 601-612. doi: http://dx.doi.org/10.1016/j.berh.2013.10.004

Dunn, K.M., Hestbaek, L., & Cassidy, J.D. (2013). Low back pain across the life course. Best Practice & Research in Clinical Rheumatology, 27(5), 591-600.

Hestbaek L, Leboeuf-Yde C, Engberg M, Lauritzen T, Bruun NH, Manniche C. (2003). The course of low back pain in a general population. Results from a 5-year prospective study. Journal of Manipulative & Physiological Therapeutics, 26(4):213–9.

Hestbaek L, Leboeuf-Yde C, Manniche C. (2003). Low back pain: what is the long-term course? A review of studies of general patient populations. European Spine Journal, 12(2):149–65.

Vasseljen, O., Woodhouse, A., Bjorngaard, J.H., & Leivseth, L. (2013). Natural course of acute neck and low back pain in the general population: The HUNT study. Pain, 154(8), 1237-1244.