INTERVIEW: Pain Management Challenges: Research, Access, Costs, Education and Public Awareness

Abstract

Barry J Sessle graduated from dental school in Sydney, Australia, in 1963 and went on to complete a Masters in oral biology. This reinforced his emerging interest in research, which eventually led to his PhD in Sydney and postdoctorate work in dental neuroscience at the NIH. He joined the University of Toronto Faculty of Dentistry, Canada, in 1971 and was Dean of the Faculty from 1990 to 2001. He is currently Professor, Faculty of Dentistry, and Canada Research Chair, and a former President of the International Association for the Study of Pain (IASP), the Canadian Pain Society (CPS) and the International Association of Dental Research. Dr Sessle has received many distinctive awards and honors. For example, he is the only dentist to be elected to the Royal Society of Canada and the Canadian Academy of Science (in 1996). He is also the only dentist or dental academic to be President of either the IASP or CPS. He was honored by the American Academy of Orofacial Pain during their annual meeting in 2004 and given an award for his dedication to pain research, service and teaching. This is only the second such award given in the 30 years of the organization‘s existence. In 2004, he was awarded the Institute of Musculoskeletal Health and Arthritis (IMHA) Quality of Life Research Award in recognition of the highest rank IMHA-related grant in 2004 for the Canadian Institutes of Health Research competitions. Dr Sessle is also a renowned lecturer, presenting 15–20 lectures internationally each year and, in addition, has published 11 books and over 330 papers. He is editor-in-chief of the Journal of Orofacial Pain, and a member of the Editorial Advisory Board of Pain Management. In this article, Dr Sessle discusses his career and current work with the Launch Editor, Laura Dormer.

Q What originally led to your interest in craniofacial pain & its mechanisms?

I have both dental and neuroscience training, which in the 1960s was an unheard of combination. I graduated from the University of Sydney with a dental degree, studied for a Masters degree in oral biology and then undertook a PhD in neuroscience. Towards the end of my dental training I then realized how little we knew about orofacial pain, and especially the role that underlying neural mechanisms might be playing. I thought that insight into this could be gained if one were to conduct research in the neuroscience field, so it was those gaps in knowledge that drove me to undertake a PhD in this area. However, at that time, I am not even sure neuroscience was a commonly used word! There were very few people working in the neuroscience field, compared with today when the Annual Meeting of the Society of Neuroscience, largely a North American-based society, typically attracts an attendance of 30,000–35,000 people. My career developed hand-in-hand with the explosion of neuroscience research.

I was very lucky because almost the only person conducting research in trigeminal neuroscience (i.e., neuroscience related to the trigeminal nerve that innervates the face, mouth and jaw) was in Sydney. I was guided by individuals at the University of Sydney to Ian Darian-Smith, a professor at the University of New South Wales, and became his first PhD student.

Another stroke of fortune followed this. I wanted to carry on my research at the postdoctoral level and, as most Australians do, wanted to leave the country for a while and experience other parts of the world and broaden my expertise. It just so happened that Ron Dubner, who subsequently became a pioneer in pain research in both the trigeminal and spinal systems, was just setting up his laboratory at the US NIH, and I became his first visiting scientist.

Towards the end of my 2-year stay with Dr Dubner a colleague of his in Toronto was looking for a scientist who might be interested in orofacial sensory motor function, which led to me moving there in 1971, and where I have been ever since. A lot of things fell into place for me as I established my career.

Q Are there any other colleagues you have worked with that have influenced the path your research has taken?

In addition to Professor Darian-Smith and Dr Dubner, I should also mention that soon after I finished my dentistry studies I was very well guided by professors in oral pathology and oral biochemistry, who pointed me in the direction of a research/academic career. As I was studying dentistry it became clear to me that I did not have the full interest and drive to be ‘drilling and filling‘ teeth for the rest of my life. However, I had developed a keen interest in oral biology and, therefore, those professors were instrumental in fostering the early phase of my career.

I have been fortunate enough to work with a large number of collaborators. It is important to work with colleagues who bring particular expertise that one is not so rich in. We currently have collaborators in Australia, Japan and Scandinavia, and on-site here in Toronto we have around a dozen people, including both scientists and graduate students.

Throughout my career, everybody I have worked with has always been very collegial; any collaborations I have had have always added value and broadened my insights and expertise, and I am very grateful to all those with whom I have worked.

Q You currently hold the Canada Research Chair in Craniofacial Pain & Sensorimotor Function; what research areas are you currently focusing on?

The Canada Research Chair program was set up by the federal government around 2000, with the aim of minimizing the ‘brain drain‘ in Canada. The Canada Research Chairs were established at senior (Tier 1) and junior (Tier 2) levels, to encourage senior researchers to remain in the country and at the junior level to provide academic positions for exceptional young investigators or attract Canadians back if they are working elsewhere. The salary for each of these chairs is supported by the federal government, thereby reducing some of the financial burden on the universities. A total of 2000 of these positions were established, encompassing all academic disciplines, including health.

My research is mainly supported by both the Canadian Institutes of Health Research (CIHR) and also by the US NIH. For the last 30–40 years this has focused on two major areas. One focus is on pain, and, not unrelated, my second focus is on motor control mechanisms in the brain controlling movement of the face, jaw and tongue. In more recent years I have tended to link the two; for example, looking at the movement effects of pain and the mechanisms in the brain that may be involved. A bridge between these two areas of focus is not only what effects pain may have on the motor system, but also the neuroplasticity of the brain (structural and/or functional changes that occur in the brain) related to both pain and motor function; for example, how you learn a new motor skill as you are maturing, or how your motor system adapts to pain or other changes in the external environment. As a dentist, I also am particularly interested in how patients adapt to new oral prostheses or a restorative procedure they have undergone. At present we are particularly interested in studying the neuroplastic mechanisms in the cerebral sensory-motor cortex that control orofacial movements, using animal models, in particular, and also some correlated human studies. We are looking at ways the sensory-motor cortex changes to allow for adaptation to an altered oral state, and how the sensory-motor cortex is involved in the acquisition of new motor skills that might involve the orofacial area.

In my pain research we continue to be particularly interested in the primary afferent and brain stem mechanisms involved in pain in the face, mouth and jaws, and looking at what processes are involved in modulating those mechanisms. In particular at the moment our focus is not only on neuronal mechanisms, but also on non-neural processes that might have a role to play. We are especially interested in neural processes that involve purinergic mechanisms and NMDA mechanisms. On the non-neural side, we are interested in the role that glial cells may be playing in modulating the transmission of pain signals from the face, mouth and jaw.

Q What would you consider to be your greatest achievement in the field?

It is hard to pinpoint a specific achievement, as I have published around 350 papers and book chapters, and books related to different aspects of my research. I believe I have significantly contributed to elucidating the brain mechanisms that underlie the transmission of pain signals from the face, mouth and jaw, and some of the neurochemical and non-neural processes that modulate the transmission of those pain signals. This has provided insight and helped to explain some of the clinical features of many acute and chronic pain conditions that we see in the craniofacial region, as well as providing insight into how a number of therapeutic approaches that are used to manage these pain conditions may operate. By providing these insights into transmission processes and their controlling mechanisms we have helped improve understanding in the field and in the long run, and the main reason for all of this research, helped patients who have chronic pain, particularly in the craniofacial region.

Q What are the biggest challenges we face in managing pain?

The challenges we face in pain management are multidimensional. In addition to my current pain research, I am also an advocate for the pain field and there are a number of important challenges.

On the research side, there is the challenge of increasing our understanding of the mechanisms by which an acute injury can transition sometimes into chronic pain, and why this occurs in only some individuals, whether that is humans or other animal species. Why do some individuals develop chronic pain after what, in some cases, seems a trivial injury, and others do not? Why is it that in some other, more general systemic diseases or disorders that involve pain, such as diabetes or cancer, some individuals experience more pain than others? Genetic and environmental factors are the two most likely sets of influences bearing on these questions. Another related challenge is that in the case of most chronic pain conditions, particularly in the craniofacial region, we still do not know the etiology of the condition. We are beginning to learn more about the mechanisms underlying the pathogenesis and mechanisms contributing to chronicity but we also need to gain insight into the processes controlling the transmission process, in order to identify potential targets for drug development.

There are other, broader challenges that may vary from one country to another. In Canada there is the problem of access to appropriate and timely pain management. A number of recent surveys, supported by the Canadian Pain Society, have indicated that there are very long waiting times for treatment; on average, several weeks or months. This is particularly serious, as it has been documented that if acute pain or injury is not treated effectively early on, it can develop into a chronic pain condition and become worse and worse if it is not treated properly.

Part of the problem with access to timely, appropriate care is that a lot of clinicians especially at the primary care level, be it family physicians, dentists, nurses, physiotherapists and so on, do not have a good grounding in pain and pain management, despite their years as health professional students and as healthcare practitioners. A study, supported by the Canadian Pain Society, surveyed the formal pain content in the curricula of many health professional programs (i.e., medicine, dentistry, pharmacy, nursing, physiotherapy and occupational therapy) in Canada [1]. As a comparator, the study looked at the formal pain content in veterinary medicine schools in Canada. Information was obtained for over 40 programs, and the mean formal pain content in the dental and medical schools in Canada (not counting my own university, where we have a specific program that addresses this) was 15–16 h throughout the whole 4–5-year program. There were some schools (medical, dental and some others) that had none at all! By contrast, at the veterinary medicine schools the formal content averaged 87 h. I would make the tongue-in-cheek point that our furry, domesticated friends are receiving treatment from people who are much more knowledgeable about pain management than our human patients are. The situation is probably comparable in many countries; for example, a similar study was carried out in Britain that found strikingly similar data [2].

Another challenge is public awareness, particularly that of policymakers, regarding the crisis we are facing in pain. Surveys carried out throughout Europe, as well as Canada, the USA and other countries, indicate that chronic pain occurs in 15–30% of the adult population, and the associated socioeconomic costs are enormous. It has been estimated in Canada that the direct health costs for chronic pain are around CAN$6 billion a year. If you also factor in lost productivity, lost tax revenue and so on, this increases to over CAN$30 billion a year [3]. In the USA, surveys have found the costs to be in the order of US$100–200 billion a year [4]. To put that in perspective, that is equivalent to what it has been costing the USA for every year of the Iraq war ($100–150 billion a year). Most people are not aware of this, including policymakers, so those of us in the pain field have a lot of work to do to raise awareness of this issue and to encourage those who are in power to improve the healthcare system and to reduce the huge socioeconomic burden of pain.

A further problem is the very low levels of funding for pain research, which is remarkably disproportionate to the level of the health problem. For example, another survey supported by the Canadian Pain Society found that on average, pain research in Canada is being funded at a level of approximately CAN$15–20 million a year, whereas research into cancer, which is no more prevalent, is funded at approximately $400 million a year [5]. Funding for pain research in Canada represents less than 1% of the total CIHR budget. Despite the prevalence of chronic pain in Canada being around 18–20%, less than 1% of funding is going into that field. Surveys in the USA have also shown that less than 1% of NIH funding goes to pain research. Again, this is a challenge that needs to be addressed with the policymakers, to increase awareness of the pain crisis and the need to channel more funding into pain research to improve our understanding of pain and ways to improve its management [5].

Q To what extent do you think we are currently able to manage the psychological factors of pain?

Although I am not an expert on psychological factors, my thoughts on this go back to the deficiency in education of most healthcare professionals, not appreciating, for example, the extent of the multidimensionality of pain, particularly chronic pain. There are many different factors that influence the expression of pain in a patient, and many of these are so-called ‘psychological‘ factors. These can be related to: cognition, the person‘s understanding of the pain; any emotional factors that may be impacting on them at that time, such as stress and anxiety; and the motivation to obtain pain treatment. Management approaches that tap into these aspects might help the patient at least live with their pain, although not necessary cure their pain, and thereby improve their quality of life and functioning. Many chronic pain conditions are very functionally disabling, and more attention needs to be given to these aspects.

Q Finally, what do you think will be the hot topics in pain research over the next few years, and what are the future directions of your research?

Major research areas will include the investigation of the mechanisms involved in the transition from acute injury to chronicity, the role that genetic and environmental factors might be playing, and the role of non-neural elements, such as glial cells. There is recent evidence from our group and others that glial cells seem to play a crucial role in the development and maintenance of chronic pain states, at least in animal models. The basic science pain field is gaining much more insight into some of the intracellular signaling mechanisms and molecular processes that are involved in pain transmission, signaling and modulation. These are particularly hot research topics, from the basic science point of view, and this is information that may have clinical significance. We also need to pay more attention to utilizing animal models of chronic pain; a lot of the pain information that has been gained in the pain field over the last 30–40 years or more is from acute pain models. While much of this information does translate and provide insights into chronic pain, more insights would be gained by wider use of chronic pain models. In our own research, we have several chronic orofacial pain models of inflammatory and neuropathic pain, and that is an area where we will focus.

We will also be continuing our sensory-motor cortex research. We will be looking further at the role that neuroplasticity and adaptive mechanisms in the sensory-motor cortex may play in controlling jaw, face and tongue movements, and in our ability to function and adapt to changes in the oral cavity, including pain. We are finding that considerable neuroplastic changes occur in the sensory-motor cortex in our animal models, not only with respect to pain, but also, for example, if we extract or replace teeth. These are the areas where my sensory-motor research program will be focused.

Financial & competing interests disclosure

Barry J Sessle is a member of the national Cymbalta advisory committee of Lilly, Canada, and research grant review committee of Pfizer, Canada, and recipient of a research grant from Pfizer, Canada. He has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.