European journal of pain : EJP
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Randomized Controlled Trial
Effects of the carrier frequency of interferential current on pain modulation and central hypersensitivity in people with chronic nonspecific low back pain: A randomized placebo-controlled trial.
Interferential current (IFC) is commonly used for pain relief, but the effects of carrier frequency of the current and its action on pain mechanisms remain unclear. This randomized placebo-controlled trial tested the effects of IFC in people with chronic nonspecific low back pain. ⋯ These results suggest that although the IFC has changed some physiological mechanisms of pain and showed decrease frequency use of pain medication, there was no change in the primary aim, pain intensity. WHAT DOES THIS STUDY ADD?: The interferential current (IFC) presented advantages in the physiological measures of pain and showed decrease frequency use of pain medication. Future studies should investigate analgesic intake with IFC treatment.
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In recent years, changes in brain structure and function have been studied extensively in patients with complex regional pain syndrome (CRPS) following clinical observations of altered central processing of sensory stimuli and motor control. However, concerning MRI data, the evidence is complex to interpret due to heterogeneity in statistical methods and results. ⋯ Previously published MRI-based evidence for altered brain structure and function in rest in CRPS patients is not consistent and our data suggests that no such phenomenon exists. WHAT DOES THIS STUDY ADD?: This article does not replicate the previous found results. The reported evidence in MRI literature of aberrant neuroplasticity in CRPS patients is inconsistent in terms of localization, quantity and directionality of changes in brain structure and function.
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Cold-evoked potentials (CEPs) are known to assess the integrity of A-delta fibres and the spinothalamic tract. Nevertheless, the clinical value was not investigated previously. The aim of this study was to measure CEPs in 16 healthy subjects from the face, hand and foot sole and to investigate whether CEPs reliably detect A-delta fibre abnormalities. ⋯ CEPs were reliably recorded in healthy subjects at the hand, face and foot. Experimentally induced reversible A-delta fibre function loss was detected by CEPs. Functional recovery was assessed as well. This study is basis for further CEP evaluation studies and might be the first step for implementing CEPs in clinical routine for the early diagnosis of small-fibre disease. WHAT DOES THIS STUDY ADD?: Cold-evoked potentials are capable of reliably measuring A-delta fibre integrity, loss of function and functional recovery in healthy subjects, which is an essential prerequisite for diagnostic use in patients with small-fibre disease.
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There is evidence that sensitivity to noxious stimuli differs between the sexes and across the body, but few studies have investigated differences in the perception and experience of acute pain stimuli across the body in healthy individuals. ⋯ Moreover, these insights are helpful for the design of studies investigating pain experience in healthy persons in experimental or clinical settings. WHAT DOES THIS STUDY ADD?: We tested sensitivity to acute suprathreshold thermal stimulations across a range of body sites to investigate for potential variability. We found significant differences in the perceived intensity and unpleasantness of noxious and innocuous thermal stimuli at the wrist and lower back, compared with the shoulder and leg. These results suggest that pain experience is driven by receptor density or the relative functional importance of these sites.
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Habituation refers to the brain's inhibitory mechanism against sensory overload and its brain correlate has been investigated in the form of a well-defined event-related potential, N100 (N1). Fibromyalgia is an extensively described chronic pain syndrome with concurrent manifestations of reduced tolerance and enhanced sensation of painful and non-painful stimulation, suggesting an association with central amplification of all sensory domains. Among diverse sensory modalities, we utilized repetitive auditory stimulation to explore the anomalous sensory information processing in fibromyalgia as evidenced by N1 habituation. ⋯ Fibromyalgia patients failed to demonstrate auditory N1 habituation to repetitively presenting stimuli, which indicates their compromised early auditory information processing. Our findings provide neurophysiological evidence of inhibitory failure and cortical augmentation in fibromyalgia. WHAT'S ALREADY KNOWN ABOUT THIS TOPIC?: Fibromyalgia has been associated with altered filtering of irrelevant somatosensory input. However, whether this abnormality can extend to the auditory sensory system remains controversial. N!00, an event-related potential, has been widely utilized to assess the brain's habituation capacity against sensory overload. WHAT DOES THIS STUDY ADD?: Fibromyalgia patients showed defect in N100 habituation to repetitive auditory stimuli, indicating compromised early auditory functioning. This study identified deficient inhibitory control over irrelevant auditory stimuli in fibromyalgia.