Research and Education Highlights

Baseline functional connectivity of key nodes in pain processing and modulation determine subsequent pain ratings of an ecologically valid model of orofacial pain

Posted on 14-10-2021 — Neuroimaging studies have identified that individual differences in pain sensitivity are related to structural gray matter differences and functional connectivity between brain regions involved in pain processing. However, experimental pain models in these laboratory studies are limited in ecological validity, as they do not mimic the persistent pain that typically occurs in real-life experiences. UTCSP members Dr. Iacopo Cioffi and Dr. Massieh Moayedi and colleagues investigated whether baseline structure and function of key brain regions involved in ascending and descending pain pathways correlate with subsequent peak pain intensity ratings induced by an ecologically and clinically relevant orofacial pain model.

UTCSP members showcase their pain research at Neuroscience 2019

Posted on 18-11-2019 — From October 19 to 23 2019, the Society for Neuroscience hosted their 49th Annual Meeting in Chicago, IL. It was undoubtedly an important and lively event with 27,832 attendees from 75 countries, 13,677 abstract presentations, and 833 sessions. This platform provided the opportunity for UTCSP scientists and trainees to showcase their exciting research through poster and oral presentations. The three main nanosymposiums on pain this year were: 1) Pain and Itch Behavior, Circuitry, and Novel Techniques, 2) Pain Imaging and Perception, and 3) New Approaches for Pain Assessment and Treatment. UTCSP trainees were among the speakers of these sessions.

Project ECHO Ontario Chronic Pain and Opioid Stewardship: minimizing distances and amplifying evidence-based care

Posted on 18-11-2019 — The Project extension for community healthcare outcomes (Project ECHO) is a bidirectional teaching strategy that aims to disseminate knowledge and to increase the implementation of best practice in primary care in remote areas. Ontario has implemented the project since 2014 as the ECHO Ontario Chronic Pain and Opioid Stewardship. This unique educational model offers training via videoconferencing for primary care providers (PCP) to deliver specialised care for chronic pain disorders.

The link between pain and memory in the medial temporal lobe

Posted on 13-09-2019 — The medial temporal lobe (MTL) is primarily thought to be responsible for memory and cognition. However, several functional neuroimaging studies have shown the involvement of this brain region in both the response to experimental pain in healthy individuals and in patients with chronic pain. Interestingly, the well-known case of patient H.M., who underwent bilateral MTL resection for epilepsy, had reported an unusually high tolerance for heat pain. These previous findings suggest the involvement of the MTL in nociception and pain modulation, in addition to its well-recognized role in memory.

Children with anxiety recall more pain 1 year post-surgery

Posted on 13-09-2019 — When recalling post-operative pain, patients who have a negatively-biased recall of pain (i.e. recalled pain is worse than originally reported pain) are at greater risk for the development of chronic pain. In this study by UTCSP scientists, Joel Katz, Jennifer Stinson, and colleagues sought to identify risk factors that promote negatively-biased recall of post-surgical pain in children. In this prospective study, the authors followed patients at several timepoints throughout their first year post-surgery and asked whether anxiety pre- and post-surgery in children was correlated with negatively-biased recall of their post-operative pain. Specifically, they assessed 3 forms of anxiety: pain anxiety (anxiety during, or in anticipation of, pain), anxiety sensitivity (sensitivity to the symptoms experienced with anxiety), and pain catastrophizing (helplessness or magnification of pain) and three aspects of their current and recalled pain intensity: pain at rest, pain during movement, and pain unpleasantness.

Gabapentin upregulates GABAA receptor δ subunit – a novel mechanism of action

Posted on 27-05-2019 — Gabapentin (also known as Neurontin) is clinically prescribed for the treatment of seizures, pain, and anxiety. While gabapentin is known to modulate voltage-gated calcium channels, some studies have suggested the effects of gabapentin are also dependent on GABAergic inhibition. However, gabapentin neither binds GABA receptors nor increases GABA release, thus its precise mechanisms of action remain unclear and is what UTCSP scientists, Dr. Beverly Orser, Dr. Robert Bonin, and collaborators, aimed to uncover.

Conditioned pain modulation is not unidirectional: both hyper- and hypoalgesia can arise depending on the stimulus

Posted on 28-02-2019 — The advent of technology and mobile health apps has transformed the way people monitor, manage, and communicate health-related information. For pain, “Manage My Pain” is a mobile health app used by thousands of individuals to measure and manage their pain. It also has the capacity for large-scale, real-world data collection to advance pain research, treatment, and policy. In particular, data mining and machine learning methods can be used to analyze multimodal and dynamic features as well as build models for prediction. This may ultimately help us understand how pain changes across time within users and to allow for the development of effective coping strategies. 

Large-scale data analysis of pain volatility from users of the “Manage My Pain” app

Posted on 28-02-2019 — The advent of technology and mobile health apps has transformed the way people monitor, manage, and communicate health-related information. For pain, “Manage My Pain” is a mobile health app used by thousands of individuals to measure and manage their pain. It also has the capacity for large-scale, real-world data collection to advance pain research, treatment, and policy. In particular, data mining and machine learning methods can be used to analyze multimodal and dynamic features as well as build models for prediction. This may ultimately help us understand how pain changes across time within users and to allow for the development of effective coping strategies. 

Sexual dimorphism in pain hypersensitivity mechanisms is conserved across rodent species

Posted on 19-12-2018 — Sex differences in the role of spinal microglia, immune cells of the central nervous system, in pain signalling have only recently been discovered using mouse models. Now, in this study conducted by UTCSP scientists in Dr. Michael Salter’s group and collaborators, they showed that this sex difference is conserved across species by examining rats. Rats are an excellent species to test if sex differences in microglia involvement of chronic pain are conserved because certain immune responses and immune-related genes differ between mice and rats.

Diffusion tensor imaging as a clinically translatable prognostication tool for neurosurgery

Posted on 19-12-2018 — Outcomes of neurosurgical treatments for chronic pain are typically evaluated using clinical diagnostic measures. These measures, while important, are limited because they do not provide objective information about treatment effects nor offer any prognostic value. Advanced modalities of imaging may be used as a tool to monitor the effects of treatment and predict whether patients will achieve long-term pain relief.

Prediction of response to ketamine treatment using quantitative sensory testing and brain imaging in patients with neuropathic pain

Posted on 25-10-2018 — Neuropathic pain is often difficult to treat, significantly affecting quality of life. Intravenous infusion of ketamine is a growing treatment option for patients with neuropathic pain and has been shown to provide effective and long-term pain relief. However, almost half of patients that receive this therapy do not achieve analgesic effectiveness and the factors that predict response to ketamine treatment remain unknown.

Microglial pannexin-1 as a target for joint pain

Posted on 25-10-2018 — Arthritis is a debilitating condition that causes chronic joint pain. While the pathology of arthritis is characterized by peripheral joint inflammation, the associated pain arises from activation of nociceptive circuits from the periphery that converge in the spinal cord. Since such activity can lead to central sensitization through activation of microglia, a central nervous system-resident immune cell, it is possible that microglia drive joint pain.

Reviewing psychological interventions for post-surgical pain

Posted on 16-03-2018 — Chronic post-surgical pain (CPSP) is pain following surgery that persists beyond the expected recovery period, and which cannot be explained by known biological causes. Psychological and behavioural interventions including cognitive behavioural therapy (CBT), acceptance commitment therapy (ACT) and mindfulness-based psychotherapy can reduce pain, distress, and disability associated with CPSP. Recently, strong evidence has been presented suggesting that psychological intervention could be an important part of the surgical process, and could assist patients who are pre- or post-surgery from ever developing pathological pain. However, the body of literature on behavioural interventions for CPSP is limited. UTCSP members Dr. Joel Katz and Dr. Hance Clarke, lead author Dr. Judith L. Nicholls, and colleagues performed a systemic review of randomized controlled trials (RCTs) on psychological interventions for CPSP.

Defining the Diversity of Pain Processing Neurons in the Spinal Cord

Posted on 16-03-2018 — The superficial dorsal horn (SDH) of the spinal cord is responsible for the relaying of all pain information from the periphery up to the brain where it becomes part of our sensory experience. However, the neurons in these layers do not just serve as a relay station, but also as a hub. The vast majority of neurons in these layers are actually interneurons that receive and process pain information, in a complicated network of excitatory and inhibitory communication. The exact function and structure of this network is still being investigated, however deficits in inhibition and overexcitation have been implicated in the manifestation of clinical chronic pain symptoms.

A multidisciplinary approach to the care of chronic postsurgical pain: a case report by the Transitional Pain Service

Posted on 16-05-2017 — The serious risks of opioid use (including side effects, dependence, tolerance, and overdose mortality) have raised concerns about safe opioid prescribing and management. Opioid-dependent chronic pain patients who undergo major surgery are especially vulnerable. The current postsurgical care provides little guidance and education for patients to manage their pain. The Toronto General Hospital Transitional Pain Service (TPS) is a novel team that provides specialized, multidisciplinary care for chronic postsurgical pain patients. In a recent case report, UTCSP members Dr. Hance Clarke, Dr. Joel Katz, and colleagues describe the postsurgical care by the TPS team of a patient with complex chronic pain and high opioid dependence.

Reflecting on the 2017 UTCSP Annual Scientific Meeting

Posted on 14-03-2017 — On February 28th, the UTCSP held its Annual Scientific Meeting at the Toronto Rehabilitation Institute. After a welcome and introduction by Drs. Hance Clarke, Rob Bonin, and Bonnie Stevens, attendees had the opportunity to hear from several speakers, including UTCSP faculty and trainees with expertise in both basic and clinical pain research.

Structural neuroimaging reveals the peripheral and central contributions to trigeminal neuralgia pain

Posted on 14-03-2017 — Trigeminal neuralgia (TN) is a chronic neuropathic facial pain disorder, considered as one of the most painful conditions known to medicine. The characteristic feature of TN involves severe episodes of electric shock-like unilateral facial pain. Since a viable animal model of TN has not been established, the etiology and pathophysiological mechanisms of TN remains elusive. In a recent review article, UTCSP members Drs. Danielle DeSouza, Mojgan Hodaie, and Karen Davis discuss their body of work on how structural magnetic resonance imaging (MRI), including diffusion tensor imaging (DTI), can reveal peripheral and CNS abnormalities of TN.

A microglial pannexin-1 mechanism is critical for morphine withdrawal

Posted on 14-03-2017 — Morphine is the gold standard medication for pain management due to its potent analgesic properties. Unfortunately, morphine is also associated severe withdrawal symptoms including nausea, chills, and severe headaches. These symptoms often negatively impact a patient’s attempts to stop opiate-based therapies. As a result, there is significant interest in trying to alleviate negative side effects without attenuation of morphine’s analgesic effect. However, the current understanding of the mechanisms underlying withdrawal is limited.

Opioids, musculoskeletal disorders, and work-related outcomes

Posted on 23-01-2017 — Musculoskeletal disorders (MSDs) such as strains, sprains, fractures, and arthritis are a common cause of work disability and absenteeism. Current guidelines suggest that opioid medications should be prescribed for MSDs only when pain is severe and unresponsive to non-opioid analgesics. However, in some cases best practice guidelines are not being followed and opioids are overprescribed for MSDs, potentially contributing to work disability. 

A sweet solution for reducing procedural pain in neonates

Posted on 23-01-2017 — Sweet solutions have been repeatedly demonstrated to be analgesic in neonates undergoing medical procedures. Despite the extent of evidence for the efficacy of this intervention, clinical trials continue to be conducted using placebo/no-treatment groups. Thus, Dr. Bonnie Stevens and colleagues conducted a cumulative meta-analyses (CMAs) on the impact of sugar solutions on behavioural pain outcomes.