Pain
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Comparative Study
Central poststroke pain and reduced opioid receptor binding within pain processing circuitries: a [11C]diprenorphine PET study.
Based on concepts that endogenous opioids participate in neural transmission of pain, the present study in central poststroke pain (CPSP) patients investigated changes in opioid receptor (OR) binding in neural structures centrally involved in the processing of pain. Five patients with central pain after lesions in the brain stem, thalamus or parietal cortex and twelve healthy volunteers underwent a [11C]diprenorphine positron emission tomography study. Binding potentials were calculated using a reference region model in all subjects. ⋯ Individual extracted binding values disclosed a reduced binding in these regions in all patients independent from the particular lesion site. The poststroke pain syndrome is associated with a characteristic pattern of reduced OR binding within the neural circuitry processing pain. It is suggested that an imbalance of excitatory-inhibitory mechanisms in certain brain structures, as evidenced in decreased [11C]diprenorphine binding, is one of the causes or the consequences of poststroke pain.
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Comparative Study
Development and validation of the Neuropathic Pain Symptom Inventory.
This study describes the development and validation of the Neuropathic Pain Symptom Inventory (NPSI), a new self-questionnaire specifically designed to evaluate the different symptoms of neuropathic pain. Following a development phase and a pilot study, we generated a list of descriptors reflecting spontaneous ongoing or paroxysmal pain, evoked pain (i.e. mechanical and thermal allodynia/hyperalgesia) and dysesthesia/paresthesia. Each of these items was quantified on a (0-10) numerical scale. ⋯ It included: (i) assessment of the test-retest reliability of each item, (ii) determination of the factorial structure of the questionnaire and analysis of convergent and divergent validities (i.e. construct validity), and (iii) evaluation of the ability of the NPSI to detect the effects of treatment (i.e. sensitivity to change). The final version of the NPSI includes 10 descriptors (plus two temporal items) that allow discrimination and quantification of five distinct clinically relevant dimensions of neuropathic pain syndromes and that are sensitive to treatment. The psychometric properties of the NPSI suggest that it might be used to characterize subgroups of neuropathic pain patients and verify whether they respond differentially to various pharmacological agents or other therapeutic interventions.
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Comparative Study
Pattern-reversal visual-evoked potentials in children with migraine and other primary headache: evidence for maturation disorder?
Recently, evidence for a disturbed maturation of cerebral information processing in migraine came from studies investigating the auditory-evoked contingent negative variation and the auditory-evoked potential from childhood to adulthood. This study is to clarify whether age-dependent development is altered also for the processing of visual stimuli in migraine. Components of pattern-reversal visual-evoked potentials at four different spatial frequencies (which can preferentially activate the magno- and the parvocellular visual system) were compared between children aged 6 and 18 years with primary headache (N = 123; 67 migraine without aura, MO; 32 migraine with aura, MA; 24 tension-type headache, TH) in the headache-free interval and healthy controls (N = 82). ⋯ In headache-free controls, N135 latency reduction between pre- and post-puberty age was most pronounced at high spatial frequency. The main 'decline' of N135 latency with increasing age was shifted to lower spatial frequencies in the headache subgroups. The results give evidence that maturation of visual processing is partly disturbed in migraineurs.
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Comparative Study
Sex differences in pain perception and anxiety. A psychophysical study with topical capsaicin.
Much evidence indicates that women experience painful stimuli as more intense than men do. Nevertheless, some data suggest that sustained low-level pain may be more disturbing to men than to women. The current experiment evaluated the hypothesis that pain is more disturbing for men than for women by comparing across genders sensory and emotional aspects of pain evoked by capsaicin. ⋯ After removing the capsaicin, there was no overall effect of sex on either intensity (P = 0.18) or unpleasantness (P = 0.37) of the residual sensation. However, men still showed a positive correlation between anxiety and the intensity and unpleasantness of the sensation. Our data confirm with the topical capsaicin model that women rate pain higher than men, but despite their lower pain ratings, males have more anxiety related to pain.