Pain
-
Headache disorders are highly prevalent and debilitating, with limited treatment options. Previous studies indicate that many proinflammatory immune cells contribute to headache pathophysiology. Given the well-recognized role of regulatory T (Treg) cells in maintaining immune homeostasis, we hypothesized that enhancing Treg function may be effective to treat multiple headache disorders. ⋯ Furthermore, treating mice with ld-IL2 1 to 7 days after mild traumatic brain injury effectively prevented as well as reversed the development of behaviors related to acute and chronic post-traumatic headache. In a model of medication overuse headache, Ld-IL2 completely reversed the cutaneous hypersensitivity induced by repeated administration of sumatriptan. Collectively, this study identifies ld-IL2 as a promising prophylactic for multiple headache disorders with a mechanism distinct from the existing treatment options.
-
Sodium channel Nav1.7, encoded by the SCN9A gene, is a well-validated target that plays a key role in controlling pain sensation. Loss-of-function mutations of Nav1.7 can cause a syndrome of profound congenital insensitivity to pain in humans. Better understanding of how the loss of Nav1.7 leads to loss of pain sensibility would help to decipher the fundamental mechanisms of nociception and inform strategies for development of novel analgesics. ⋯ We observed, however, that after rimonabant administration, Nav1.7 loss-of-function but not WT rats displayed abnormal behaviours, such as enhanced scratching, caudal self-biting, and altered facial expressions; the underlying mechanism is still unclear. Dorsal root ganglion neurons from Nav1.7 loss-of-function rats, although hypoexcitable compared with WT neurons, were still able to generate action potentials in response to noxious heat and capsaicin. Our data indicate that complete loss of dorsal root ganglion neuron excitability is not required for insensitivity to pain and suggest that endogenous opioid and cannabinoid systems are not required for insensitivity to pain in the absence of Nav1.7 channels in this rat Nav1.7 loss-of-function model.
-
This review identified prospective cohort studies in the general population, which showed incidence (23 papers) and risk factors (37 papers) for fibromyalgia and chronic widespread pain. Median incidence of physician diagnosed fibromyalgia in the general population was 4.3 per 1000 person-years (range = 0.33-18.8) but 14.0 (1.2-32.7) if medical illness was present. ⋯ The strongest associations were with sleep disorders, headaches and other pains, depression, and illness behaviour. These data suggest strongly that there are many aetiological routes into fibromyalgia, and future research could be enhanced by studying the underlying mechanisms relating to these risk factors.
-
The use of long-term opioid therapy for chronic pain remains common, yet data on long-term outcomes, especially after dose escalation, are sparse. This study examined potential benefits and harms associated with prescription opioid dose escalation. Participants from 2 institutions were enrolled in a 2-year prospective cohort study. ⋯ Sexual functioning worsened over time. There were no significant changes in the full sample on pain disability, sleep functioning, or experiencing a fall. In summary, patients prescribed stable doses of long-term opioid therapy may demonstrate small changes in key pain-related outcomes over time, but prescription opioid dose escalation status is unrelated to clinical outcomes.
-
Randomized Controlled Trial
Intergroup anxiety in pain care: impact on treatment recommendations made by White providers for Black patients.
Race disparities in pain care are well-documented. Given that most black patients are treated by white providers, patient-provider racial discordance is one hypothesized contributor to these disparities. Research and theory suggest that providers' trait-level intergroup anxiety impacts their state-level comfort while treating patients, which, in turn, impacts their pain treatment decisions. ⋯ This study provides important new information about intrapersonal and interpersonal contributors to race disparities in chronic pain care. These findings suggest that intergroup anxiety and the resulting situational discomfort encroach on the clinical decision-making process by influencing white providers' decisions about which pain treatments to recommend to black patients. Should these findings be replicated in future studies, they would support interventions to help providers become more aware of their trait-level intergroup anxiety and manage their state-level reactions to patients who are racially/ethnically different from themselves.