Pain
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Randomized Controlled Trial Clinical Trial
Effect of pre- or post-traumatically applied i.v. lidocaine on primary and secondary hyperalgesia after experimental heat trauma in humans.
Hyperalgesia on intradermal capsaicin application can be attenuated by systemic application of local anesthetics. We tested whether low doses of local anesthetics applied pre- or post-traumatically can reduce heat trauma-induced primary and secondary hyperalgesia in humans. Six healthy volunteers consented to the randomized, double-blind, and cross-over designed study. ⋯ Thus, local anesthetics at concentrations that do not block nerve conduction substantially affect ongoing central changes in pain processing that are induced by a real tissue trauma. A significant preemptive effect could not be demonstrated. The anti-hyperalgesic effect of lidocaine is likely based on action of central (spinal) sites, but peripheral sites may also be addressed.
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Case Reports
Patterns of spread in complex regional pain syndrome, type I (reflex sympathetic dystrophy).
There are reports that complex regional pain syndrome, type I (reflex sympathetic dystrophy; CRPS-I/RSD) can spread from the initial site of presentation, but there are no detailed descriptions of the pattern(s) of such spread. We describe a retrospective analysis of 27 CRPS-I/RSD patients who experienced a significant spread of pain. Three patterns of spread were identified. 'Contiguous spread (CS)' was noted in all 27 cases and was characterized by a gradual and significant enlargement of the area affected initially. 'Independent spread (IS)' was noted in 19 patients (70%) and was characterized by the appearance of CRPS-I in a location that was distant and non-contiguous with the initial site (e.g. ⋯ In some it may be due to a local spread of pathology (CS); in others it may be a consequence of a generalized susceptibility (IS). In the MS case, spread may be due to abnormal neural functioning spreading via commissural pathways. Alternatively, we discuss the possibility that all three kinds of spread may be due to aberrant CNS regulation of neurogenic inflammation.
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Our understanding of the natural history of chronic pain in the community is limited. This is partly due to the lack of a validated measure of chronic pain severity known to be responsive to change over time. The Chronic Pain Grade questionnaire has been shown to be valid and reliable for use in a general population as a self-completion questionnaire. ⋯ The majority of SF-36 scores changed in the hypothesized directions. Changes in CPG scores were significantly correlated with changes in most of the SF-36 domains. We concluded that the CPG is a useful and valid objective instrument for measuring change in severity of chronic pain over time and could be used in longitudinal studies of chronic pain severity.