Cancer pain and neuropathic pain are associated with A β sensory neuronal plasticity in dorsal root ganglia and abnormal sprouting in lumbar spinal cord.

Evidence suggests that there are both nociceptive and neuropathic components of cancer-induced pain. We have observed that changes in intrinsic membrane properties and excitability of normally non-nociceptive Aβ sensory neurons are consistent in rat models of peripheral neuropathic pain and cancer-induced pain. This has prompted a comparative investigation of the intracellular electrophysiological characteristics of sensory neurons and of the ultrastructural morphology of the dorsal horn in rat models of neuropathic pain and cancer-induced pain.

Rat model of cancer-induced bone pain: changes in nonnociceptive sensory neurons in vivo.

Introduction: Clinical data on cancer-induced bone pain (CIBP) suggest extensive changes in sensory function. In a previous investigation of an animal model of CIBP, we have observed that changes in intrinsic membrane properties and excitability of dorsal root ganglion (DRG) nociceptive neurons correspond to mechanical allodynia and hyperalgesia.

Objectives: To investigate the mechanisms underlying changes in nonnociceptive sensory neurons in this model, we have compared the electrophysiological properties of primary nonnociceptive sensory neurons at <1 and >2 weeks after CIBP model induction with properties in sham control animals.

Differences in electrophysiological properties of functionally identified nociceptive sensory neurons in an animal model of cancer-induced bone pain.

Background: Bone cancer pain is often severe, yet little is known about mechanisms generating this type of chronic pain. While previous studies have identified functional alterations in peripheral sensory neurons that correlate with bone tumours, none has provided direct evidence correlating behavioural nociceptive responses with properties of sensory neurons in an intact bone cancer model.

Results: In a rat model of prostate cancer-induced bone pain, we confirmed tactile hypersensitivity using the von Frey test.

iCanCope with Pain™: User-centred design of a web- and mobile-based self-management program for youth with chronic pain based on identified health care needs.

Background: While there are emerging web-based self-management programs for children and adolescents with chronic pain, there is currently not an integrated web- and smartphone-based app that specifically addresses the needs of adolescents with chronic pain.

Objectives: To conduct a needs assessment to inform the development of an online chronic pain self-management program for adolescents, called iCanCope with Pain™.

Methods: A purposive sample of adolescents (n=23; 14 to 18 years of age) was recruited from two pediatric chronic pain clinics in Ontario.

Pain-QuILT: clinical feasibility of a web-based visual pain assessment tool in adults with chronic pain.

Background: Chronic pain is a prevalent and debilitating problem. Accurate and timely pain assessment is critical to pain management. In particular, pain needs to be consistently tracked over time in order to gauge the effectiveness of different treatments.

A systematic review of the effectiveness of knowledge translation interventions for chronic noncancer pain management.

Background: Reliable evidence detailing effective treatments and management practices for chronic noncancer pain exists. However, little is known about which knowledge translation (KT) interventions lead to the uptake of this evidence in practice.

Objectives: To conduct a systematic review of the effectiveness of KT interventions for chronic noncancer pain management.

Pain-QuILT: assessing clinical feasibility of a Web-based tool for the visual self-report of pain in an interdisciplinary pediatric chronic pain clinic.

Objectives: To evaluate clinical feasibility of the Pain-QuILT (previously known as the Iconic Pain Assessment Tool) from the perspective of adolescents with chronic pain and members of their interdisciplinary health team. The Pain-QuILT (PQ), a web-based tool that records the visual self-report of sensory pain in the form of time-stamped records, was directly compared with standard interview questions that were transformed to a paper-based tool.

Methods: Qualitative, semi-structured interviews were used to refine the PQ.

Peripheral neuropathy induces cutaneous hypersensitivity in chronically spinalized rats.

Background/objectives: The present study was aimed at the issue of whether peripheral nerve injury-induced chronic pain is maintained by supraspinal structures governing descending facilitation to the spinal dorsal horn, or whether altered peripheral nociceptive mechanisms sustain central hyperexcitability and, in turn, neuropathic pain. We examined this question by determining the contribution of peripheral/spinal mechanisms, isolated from supraspinal influence(s), in cutaneous hypersensitivity in an animal model of peripheral neuropathy.

Methods: Adult rats were spinalized at T8-T9; 8 days later, peripheral neuropathy was induced by implanting a 2-mm polyethylene cuff around the left sciatic nerve.

Peripheral drive in Aα/β-fiber neurons is altered in a rat model of osteoarthritis: changes in following frequency and recovery from inactivation.

Purpose: To determine conduction fidelity of Aα/β-fiber low threshold mechanoreceptors in a model of osteoarthritis (OA).

Methods: Four weeks after cutting the anterior cruciate ligament and removing the medial meniscus to induce the model, in vivo intracellular recordings were made in ipsilateral L4 dorsal root ganglion neurons. L4 dorsal roots were stimulated to determine the refractory interval and the maximum following frequency of the evoked action potential (AP).

Understanding the information and service needs of young adults with chronic pain: perspectives of young adults and their providers.

Objective: To qualitatively explore the information and service needs of young adults (YAs) with chronic pain to inform the development of a web-based chronic pain self-management program.

Methods: A convenience sample of YAs (n=17; aged 18 to 29 y) with chronic pain was recruited from 2 adult tertiary care multidisciplinary chronic pain clinics in Ontario. Interdisciplinary health care professionals who had worked in chronic pain for at least 1 year were also recruited from these sites.

Lumbar facet joint compressive injury induces lasting changes in local structure, nociceptive scores, and inflammatory mediators in a novel rat model.

Objective. To develop a novel animal model of persisting lumbar facet joint pain. Methods.

Adapting the Iconic Pain Assessment Tool Version 2 (IPAT2) for adults and adolescents with arthritis pain through usability testing and refinement of pain quality icons.

Objectives: To evaluate usability and pain iconography of the Iconic Pain Assessment Tool Version 2 (IPAT2), a self-report instrument that combines word descriptors and representative images (icons) to assess pain quality, intensity, and location, among adults and adolescents with arthritis.

Methods: Adults with inflammatory arthritis and adolescents with juvenile idiopathic arthritis partook in a single, semistructured, audio-recorded interview to evaluate: (1) the concreteness (object representativeness) and semantic distance (pain representativeness) of the IPAT2 iconography; (2) participants' current pain; and (3) perceptions and likes/dislikes of the IPAT2. Quantitative data were summarized descriptively and a line-by-line coding analysis identified key concepts from interview transcripts.

Changes in functional properties of A-type but not C-type sensory neurons in vivo in a rat model of peripheral neuropathy.

Background: The aim of this study was to compare primary sensory neurons in controls and in an animal neuropathic pain model in order to understand which types of neurons undergo changes associated with peripheral neuropathy. On the basis of intracellular recordings in vivo from somata, L4 sensory dorsal root ganglion neurons were categorized according to action potential configuration, conduction velocity, and receptive field properties to mechanical stimuli.

Methods: Intracellular recordings were made from functionally identified dorsal root ganglion neurons in vivo in the Mosconi and Kruger animal model of peripheral neuropathic pain.

Functional changes in muscle afferent neurones in an osteoarthritis model: implications for impaired proprioceptive performance.

Background: Impaired proprioceptive performance is a significant clinical issue for many who suffer osteoarthritis (OA) and is a risk factor for falls and other liabilities. This study was designed to evaluate weight-bearing distribution in a rat model of OA and to determine whether changes also occur in muscle afferent neurones.

Methodology/principal Findings: Intracellular recordings were made in functionally identified dorsal root ganglion neurones in acute electrophysiological experiments on the anaesthetized animal following measurements of hind limb weight bearing in the incapacitance test.

Excitability of Aβ sensory neurons is altered in an animal model of peripheral neuropathy.

Background: Causes of neuropathic pain following nerve injury remain unclear, limiting the development of mechanism-based therapeutic approaches. Animal models have provided some directions, but little is known about the specific sensory neurons that undergo changes in such a way as to induce and maintain activation of sensory pain pathways. Our previous studies implicated changes in the Aβ, normally non-nociceptive neurons in activating spinal nociceptive neurons in a cuff-induced animal model of neuropathic pain and the present study was directed specifically at determining any change in excitability of these neurons.

Neuropathic pain as a process: reversal of chronification in an animal model.

Peripheral neuropathic pain arises from trauma to sensory nerves. Other types of acute neurotrauma such as stroke and spinal cord injury are treated immediately, largely to prevent secondary damage. To pursue the possibility that neuropathic pain may also be amenable to early treatment, a rat model of neuropathic pain was induced using a 2-mm polyethylene cuff implanted around one sciatic nerve.

Progesterone prevents development of neuropathic pain in a rat model: Timing and duration of treatment are critical.

Background: Progesterone is emerging as an important protective agent against various injuries to the nervous system. Neuroprotective and remyelinating effects have been documented for this neurosteroid, which is synthesized by, and acts on, the central and peripheral nervous systems. Neuropathic pain is a severe, persistent condition that is generally resistant to treatment, and poses major personal, social, and economic burdens.

The selective neuronal nitric oxide synthase inhibitor 7-nitroindazole has acute analgesic but not cumulative effects in a rat model of peripheral neuropathy.

Chronic neuropathic pain that may arise from various nerve injuries or insults remains notoriously difficult to manage. The neuronal isoform of the enzyme nitric oxide synthase (nNOS) has been shown to be involved in the spinal transmission of nociception in animal models of chronic pain. The aim of this study is to evaluate the effect of single dose and repeated administration of a selective nNOS inhibitor.

Evaluation of the Iconic Pain Assessment Tool by a heterogeneous group of people in pain.

The Iconic Pain Assessment Tool (IPAT) is a novel web-based instrument for the self-report of pain quality, intensity and location in the form of a permanent diary. Originally designed for people with central poststroke pain, the tool is being adapted for a larger, more diverse patient population. The present study aimed to collect evaluative feedback on the IPAT from a heterogeneous sample of individuals with chronic pain.

Changes in Abeta non-nociceptive primary sensory neurons in a rat model of osteoarthritis pain.

Background: Pain is a major debilitating factor in osteoarthritis (OA), yet few mechanism-based therapies are available. To address the need to understand underlying mechanisms the aim of the present study was to determine changes in sensory neurons in an animal model of OA pain.

Results: The model displayed typical osteoarthritis pathology characterized by cartilage degeneration in the knee joint and also manifested knee pathophysiology (edema and increased vasculature permeability of the joint) and altered nociception of the affected limb (hind paw tenderness and knee articulation-evoked reduction in the tail flick latency).

Alteration of sensory neurons and spinal response to an experimental osteoarthritis pain model.

Objective: To verify the biologic links between progressive cellular and structural alterations within knee joint components and development of symptomatic chronic pain that are characteristic of osteoarthritis (OA), and to investigate the molecular basis of alterations in nociceptive pathways caused by OA-induced pain.

Methods: An animal model of knee joint OA pain was generated by intraarticular injection of mono-iodoacetate (MIA) in Sprague-Dawley rats, and symptomatic pain behavior tests were performed. Relationships between development of OA with accompanying pain responses and gradual alterations in cellular and structural knee joint components (i.

Sensory and vascular changes in a rat monoarthritis model: prophylactic and therapeutic effects of meloxicam.

Objective And Design: The objective of this study was to determine the ability of meloxicam prophylaxis and therapy to blunt the effect of complete Freund's adjuvant (CFA) induced monoarthritis.

Materials And Methods: First the validity of this animal model was established by examining joint changes at multiple levels after injecting CFA into the tibio-tarsal joint. Next, meloxicam (5 mg/kg) or vehicle was administered on days 0-7 (prophylactic) and on days 7-16 (therapeutic) in separate groups of animals.

Delayed onset of changes in soma action potential genesis in nociceptive A-beta DRG neurons in vivo in a rat model of osteoarthritis.

Background: Clinical data on osteoarthritis (OA) suggest widespread changes in sensory function that vary during the progression of OA. In previous studies on a surgically-induced animal model of OA we have observed that changes in structure and gene expression follow a variable trajectory over the initial days and weeks. To investigate mechanisms underlying changes in sensory function in this model, the present electrophysiological study compared properties of primary sensory nociceptive neurons at one and two months after model induction with properties in naïve control animals.

The need for knowledge translation in chronic pain.

One in five Canadians suffers from some form of persistent or chronic pain. The impact on individual lives, families and friends, the health services sector and the economy is huge. Reliable evidence is available that the burden of persistent pain can be markedly reduced when available knowledge is applied.

Physiological evidence of a postsynaptic inhibition of the tail flick reflex by a cannabinoid receptor agonist.

Current evidence indicates that cannabinoids are antinociceptive and this effect is in part mediated by spinal mechanisms. Anatomical studies have localized cannabinoid CB(1) receptors to pre- and postsynaptic sites within the spinal cord. However, behavioural tests have not clearly indicated the relative importance of each of these sites.