The Clinical journal of pain
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Comparative Study
Chronic Widespread Back Pain is Distinct from Chronic Local Back Pain: Evidence from Quantitative Sensory Testing, Pain Drawings, and Psychometrics.
Whether chronic localized pain (CLP) and chronic widespread pain (CWP) have different mechanisms or to what extent they overlap in their pathophysiology is controversial. The study compared quantitative sensory testing profiles of nonspecific chronic back pain patients with CLP (n=48) and CWP (n=29) with and fibromyalgia syndrome (FMS) patients (n=90) and pain-free controls (n = 40). ⋯ Even after long duration CLP presents with a local hypersensitivity for PPT, suggesting a somatotopically specific sensitization of nociceptive processing. However, CWP patients show widespread ongoing pain and hyperalgesia for different stimuli that is generalized in space, suggesting the involvement of descending control systems, as also suggested for FMS patients. Because mechanisms in nonspecific chronic back pain with CLP and CWP differ, these patients should be distinguished in future research and allocated to different treatments.
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Allodynia reflects the clinical correlate of central sensitization, but it is usually neglected in clinical headache management. We aimed to report the prevalence and previously unnoticed associations of allodynia in migraineurs by a nationwide face-to-face questionnaire-based study by physicians. ⋯ The duration, severity, and disability of migraine attacks, photophobia, phonophobia, and osmophobia, as well as premonitory signs, showed significant associations with allodynia in the general population. Moreover, migraineurs with aura or family history of migraine more often reported allodynia, and allodynic migraneurs were more sensitive to hormonal changes. Allodynia, which seems to indicate higher tendency to central sensitization, should be implemented in daily headache practice to predict the prognosis and high levels of migraineous involvement.
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Randomized Controlled Trial
Prior Opioid Use Does Not Impact the Response to Pregabalin in Patients With Fibromyalgia.
Fibromyalgia (FM) is a chronic pain disorder for which pregabalin is an approved treatment in the United States. Although opioids are not a recommended treatment option, they continue to be used by many FM patients. The impact of patients' prior opioid use on their subsequent response to pregabalin has not been assessed. ⋯ FM patients respond to treatment with pregabalin with significant improvements in pain scores irrespective of prior opioid use. These data could inform treatment decisions for FM patients with prior use of opioids.
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Case Reports
Single-Fiber Recordings of Nociceptive Fibers in Patients With HSAN Type V With Congenital Insensitivity to Pain.
Nerve growth factor (NGF) is a protein important for growth and survival, but also for modulation of sensitivity of nociceptors and sympathetic neurons. The purpose of the present study was to investigate the effects of reduced NGF signaling in patients with hereditary sensory and autonomic neuropathies type V, congenital insensitivity to pain, caused by a mutation of the NGFβ gene, including a characterization of single nociceptive fibers using microneurography (MNG). ⋯ The findings of grossly intact pain thresholds compared with anamnestic insensitivity of pain in deep somatic tissue such as bone suggest a gradient of impairment dependent on different NGF availability in various tissues. Even though these patients in some aspects report insensitivity to pain, they also report chronic spontaneous pain as their main symptom, strikingly highlighting differential mechanisms of insensitivity to evoked pain versus spontaneous pain.
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A standardized assessment of central sensitization can be performed with the Central Sensitization Inventory (CSI), an English questionnaire consisting of 25 items relating to current health symptoms. The aim of this study was to translate the CSI into Dutch, to perform a factor analysis to reveal the underlying structure, examine its discriminative power, and test-retest reliability. ⋯ The original CSI was translated into Dutch and did not reveal any problems during data acquisition. The domains represented by the 4 factors may be useful in setting up specific patient profiles and treatment targets. To conclude, the Dutch CSI revealed 4 distinguishable domains, showed good internal consistency for the total score and 3 out of 4 domains, good discriminative power, and excellent test-retest reliability.