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We utilized diffusion tensor imaging (DTI) to evaluate the cerebral white matter changes that are associated with phantom limb pain in patients with unilateral arm amputation. It was anticipated that this would complement previous research in which we had shown that changes in cerebral blood volume were associated with the cerebral pain network.
Learn More >Background and Purpose- Central poststroke pain (CPSP) is a disabling condition in stroke patients, and evidence suggests that altered corticospinal and motor intracortical excitability occurs in neuropathic pain. The objective of this study was to investigate changes in motor cortex excitability and sensorimotor interaction and their correlates with clinical manifestations and alterations in somatosensory systems in CPSP patients. Methods- Fourteen patients with CPSP but no motor weakness were compared with age- and sex-matched healthy controls for motor cortex excitability and sensorimotor interaction assessed by transcranial magnetic stimulation to measure resting motor thresholds, short-interval intracortical inhibition, intracortical facilitation, and afferent inhibitions. The sensory pathway was evaluated by quantitative sensory testing, contact heat evoked potential, and somatosensory evoked potentials. Clinical pain and quality of life were assessed with validated tools. Results- The duration of CPSP was 3.3±3.0 years (ranging 0.5-10 years), and pain significantly impaired quality of life. Compared with the unaffected hemisphere, the stroke hemisphere had higher thermal thresholds, lower contact heat evoked potential amplitudes, and prolonged cortical somatosensory evoked potential latencies. There was no difference in resting motor thresholds between the stroke and unaffected hemisphere or between patients and controls. CPSP patients had a reduction in short-interval intracortical inhibition in the stroke hemisphere compared with that in the unaffected hemispheres of patients and controls. No changes were noted in afferent inhibitions between the stroke and unaffected hemispheres. The short-interval intracortical inhibition of the stroke hemisphere was negatively correlated with self-rated health on a visual analog scale and positively correlated with cortical somatosensory evoked potential latencies. Conclusions- CPSP patients with intact corticospinal tracts showed reduced motor intracortical inhibition in the stroke hemisphere, suggesting defective gamma-aminobutyric acid-ergic inhibition. This disinhibition was associated with impaired quality of life and was related to dorsal column-medial lemniscus pathway dysfunction.
Learn More >Individuals with chronic pain who misuse prescription opioids are at high risk for developing opioid use disorder and/or succumbing to opioid overdose. The current study conducted a survey to evaluate sex-based differences in pain catastrophizing, opioid withdrawal, and current pain in persons with co-occurring chronic pain and opioid misuse. We hypothesized that women with chronic pain who misused prescription opioids would self-report higher pain ratings compared with men and that the relationship between pain catastrophizing and self-reported current pain would be moderated by symptoms of opioid withdrawal in women only.
Learn More >Initiating mechanisms of migraine headache remain poorly understood and a biomarker of migraine does not exist. Inflammation pertaining to the wall of cerebral arteries and brain parenchyma has been suggested to play a role in migraine pathophysiology.
Learn More >Over half of youth with chronic pain report sleep deficiency including difficulties falling asleep, maintaining sleep, feeling unrested, and experiencing short sleep duration. Sleep deficiency has been shown to play a causal role in the development or worsening of chronic pain, and is associated with a variety of negative consequences for youth with chronic pain. The purpose of this review is to provide a summary of the literature on the interrelationship of sleep and chronic pain in adolescents. We review the impact and prevalence of sleep disturbances, conceptual models of the interrelationship of sleep and pain, biobehavioral mechanisms and risk factors, sleep assessment, and treatment of sleep deficiency and chronic pain in adolescents. Our recommendations for future research include understanding biobehavioral mechanisms that underlie the link between chronic pain and sleep deficiency to help guide development and testing of treatments for co-occurring pain and sleep disturbance in adolescents.
Learn More >The International Classification of Headache Disorders lists different subtypes of medication overuse headache (MOH), according to the medication overused. The aim of this study is to evaluate whether the different subtypes correspond to clinically distinguishable phenotypes in a large population.
Learn More >The opioid epidemic is a significant public health crisis and prescription opioids are often used to manage chronic pain, despite questionable long-term efficacy. Furthermore, co-substance (mis)use is also common among individuals with chronic pain who use opioids. Alcohol has been consistently used to manage chronic pain, partly due to its acute analgesic properties. Cannabis has also recently garnered attention in the context of pain management, though research examining its efficacy for pain has produced mixed results. Nevertheless, there is accumulating evidence that concurrent substance co-use is positively associated with use and misuse of additional substances, particularly among individuals with chronic pain. Thus, the goal of this study was to examine the main and interactive effects of alcohol use problems and cannabis use problems in relation to opioid misuse among adults with chronic pain who use opioids.
Learn More >Recent research has suggested that the magnitudes of analgesic treatment effects estimated in clinical trials have decreased over time. Implications of these findings for future sample size calculations and clinical trial research designs have not been addressed. In this article, we examine the standardized effect size (SES) for average pain intensity (API) and worst pain intensity (WPI) outcomes from randomized clinical trials (RCTs) of analgesic treatments shown to be efficacious for chronic low back pain, fibromyalgia, osteoarthritis pain, painful diabetic peripheral neuropathy, and postherpetic neuralgia that were published between 1980 and 2016. API and WPI SESs have declined over time and are approximately 0.30 in the most recent trials. This is similar to the mean SESs found in recent RCTs of efficacious antidepressant medications for the treatment of depression. We propose that in many circumstances this value should be considered when conducting sample size determinations for phase 2 and 3 analgesic RCTs. Other methods to address the challenge of modest treatment effects by increasing trial efficiency and assay sensitivity are also briefly discussed. PERSPECTIVE: This article examines continuous pain intensity data obtained from analgesic treatment trials for chronic low back pain, fibromyalgia, osteoarthritis pain, painful diabetic peripheral neuropathy, and postherpetic neuralgia. Numerical declines in standardized effect sizes (SESs) were observed, with SESs being approximately 0.30 in the most recent trials.
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