Pain
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Randomized Controlled Trial
Limb-specific autonomic dysfunction in complex regional pain syndrome modulated by wearing prism glasses.
In unilateral upper-limb complex regional pain syndrome (CRPS), the temperature of the hands is modulated by where the arms are located relative to the body midline. We hypothesized that this effect depends on the perceived location of the hands, not on their actual location, nor on their anatomical alignment. In 2 separate cross-sectional randomized experiments, 10 (6 female) unilateral CRPS patients wore prism glasses that laterally shifted the visual field by 20°. ⋯ When prism glasses made the healthy hand appear to be on the affected side of the body midline, even though it was not, the healthy hand cooled down (Δ°C=-0.30 ± 0.15°C). Friedman's analysis of variance and Wilcoxon pairs tests upheld the results (P<0.01 for all). We conclude that, in CRPS, cortical mechanisms responsible for encoding the perceived location of the limbs in space modulate the temperature of the hands.
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Randomized Controlled Trial
A pain model with a neuropathic somatosensory lesion: Morton neuroma.
A randomized, double-blind, three-period cross-over study was performed to characterize the sensory phenotype and pain demographics in patients with Morton neuroma (n=27) and to explore the effects of local administration (2mL) of placebo and lidocaine (1 and 10mg/mL) around the neuroma. Using the pain quality assessment scale (PQAS), the highest rating was seen for unpleasant pain and intensity of deep pain and the lowest for sensitive skin. Ongoing pain was reported in 32% of patients. ⋯ Following placebo treatment, pain after step-ups was similar in patients with and without hyperalgesia, indicating that the presence of hyperalgesia does not affect the pain intensity evoked by step-ups or walking. This pain model in patients with Morton neuroma allows investigation of drugs in a cross-over design and provides an opportunity to explore drug effects on both pain and QST variables. Commonly, neuromas are surgically removed and can be characterized in depth in vitro, thereby allowing close links to be established between pathophysiology and drug effect.
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Randomized Controlled Trial
Transcutaneous electrical nerve stimulation reduces pain, fatigue and hyperalgesia while restoring central inhibition in primary fibromyalgia.
Because transcutaneous electrical nerve stimulation (TENS) works by reducing central excitability and activating central inhibition pathways, we tested the hypothesis that TENS would reduce pain and fatigue and improve function and hyperalgesia in people with fibromyalgia who have enhanced central excitability and reduced inhibition. The current study used a double-blinded randomized, placebo-controlled cross-over design to test the effects of a single treatment of TENS with people with fibromyalgia. Three treatments were assessed in random order: active TENS, placebo TENS and no TENS. ⋯ No changes in functional tasks were observed with TENS. Thus, the current study suggests TENS has short-term efficacy in relieving symptoms of fibromyalgia while the stimulator is active. Future clinical trials should examine the effects of repeated daily delivery of TENS, similar to the way in which TENS is used clinically on pain, fatigue, function, and quality of life in individuals with fibromyalgia.
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Randomized Controlled Trial
Disturbed sensory perception of changes in thermoalgesic stimuli in patients with small fiber neuropathies.
The assessment of functional deficits in small fibre neuropathies (SFN) requires using ancillary tests other than conventional neurophysiological techniques. One of the tests with most widespread use is thermal threshold determination, as part of quantitative sensory testing. Thermal thresholds typically reflect one point in the whole subjective experience elicited by a thermal stimulus. ⋯ Abnormalities seen in patients in comparison to healthy subjects were: (1) delayed perception of temperature changes, both at onset and at reversal, (2) longer duration of pain perception at peak temperature, and (3) absence of an overshoot sensation after reversal, ie, a transient perception of the opposite sensation before the temperature reached again baseline. The use of DTT increases the yield of thermal testing for clinical and physiological studies. It adds information that can be discriminant between healthy subjects and SFN patients and shows physiological details about the process of activation and inactivation of temperature receptors that may be abnormal in SFN.
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Randomized Controlled Trial
Children's selective attention to pain and avoidance behaviour: The role of child and parental catastrophizing about pain.
The present study investigated selective attention to pain in children, its implications for child avoidance behaviour, and the moderating role of dimensions comprising child and parental catastrophizing about pain (ie, rumination, magnification, and helplessness). Participants were 59 children (31 boys) aged 10-16 years and one of their parents (41 mothers). Children performed a dot-probe task in which child facial pain displays of varying pain expressiveness were presented. ⋯ Furthermore, child attentional avoidance was associated with greater avoidance behaviour (i.e., lower pain tolerance) among children reporting high levels of pain magnification and those whose parents reported greater rumination about pain. The current findings corroborate catastrophizing as a multidimensional construct that may differentially impact outcomes and attest to the importance of assessing both child and parental characteristics in relation to child pain-related attention and avoidance behaviour. Further research directions are discussed.