Pain
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Comparative Study
Do patients with chronic pain selectively attend to pain-related information?: preliminary evidence for the mediating role of fear.
Preliminary evidence from a study using a modified Stroop paradigm suggests that individuals with chronic pain selectively attend to pain-related information. The current study was conducted in an attempt to replicate and extend this finding. Nineteen patients with chronic pain stemming from musculoskeletal injury and 22 healthy control subjects participated. ⋯ Ther., 34 (1996) 545-554), those with low anxiety sensitivity shifted attention away from stimuli related to pain whereas those with high anxiety sensitivity responded similarly to dot-probes regardless of the parameters of presentation. These results suggest that the operation of the information processing system in patients with chronic pain may be dependent on a patient's trait predisposition to fear pain. Theoretical and ecological implications are discussed.
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A chronic, loose constriction of the sciatic nerve in rat produces behavioral signs of spontaneous pain and cutaneous hyperalgesia (Bennett and Xie, Pain, 33 (1988) 87-107) as well as an abnormal spontaneous activity and adrenergic sensitivity of certain dorsal root ganglion (DRG) cells with axons in the injured nerve (Kajander et al., Neurosci. Lett., 138 (1992) 225-228; Xie et al., J. Neurophysiol., 73 (1995)1811-1820). ⋯ None of the fibers from uninjured nerve responded to NE or clonidine (500 microM). Since the experiments were carried out in vitro in the intact DRG, the existence of spontaneous activity in DRG cells in nerve-injured rats was independent of any blood borne chemicals, such as norepinephrine. We hypothesize that abnormal activity and adrenergic sensitivity in injured DRG neurons are due to an intrinsic alteration of the cell body membrane.
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Clinical Trial Controlled Clinical Trial
Attention and somatic awareness in chronic pain.
Empirical methods are used to explore the relationship between chronic pain, somatic awareness and attention. Using a primary task paradigm, 46 chronic pain patients performed an attentionally demanding task. ⋯ Further analysis revealed that these patients also reported high negative affect. These findings are discussed in terms of their theoretical implications for the concept of hypervigilance and their clinical implications for chronic pain control.
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Case Reports Clinical Trial
A longitudinal study of somesthetic perceptual disorders in an individual with a unilateral thalamic lesion.
Several aspects of tactile, thermal and pain perception were evaluated in an individual (R. S.) with a hemorrhagic lesion centered in her left lateral thalamus. Over a 4-year period, psychophysical evaluations were undertaken every 6-8 months, and five magnetic resonance (MR) studies were conducted. ⋯ The only change in psychophysical performance related to her right foot was a transient but intense thermal allodynia several months prior to her spontaneous pain. The MR studies over this 4-year period showed changes in the extent of edema, gliosis and/or ischemia that could be related to perceptual changes. Thus, the conspicuous observations in this thalamic lesion case were: (i) differential effects upon the various pain modalities (mechanical, heat and cold); (ii) development of thermal allodynia without mechanical allodynia, including an ipsilateral effect; (iii) a deficit in positive affective responses to temperature; and (iv) the different time courses for changes in evoked somesthetic capacity versus spontaneous paresthesias and pathological pain.