Pain
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The primary brain dysfunctions leading to the onset of a migraine attack remain largely unknown. Other important open questions concern the mechanisms of initiation, continuation, and termination of migraine pain, and the changes in brain function underlying migraine transformation. Brief trains of high-frequency repetitive transcranial magnetic stimulation (rTMS), when applied to the primary motor cortex at suprathreshold intensity (⩾120% of resting motor threshold [RMT]), elicit in healthy subjects a progressive, glutamate-dependent facilitation of the motor evoked potentials (MEP). ⋯ Results showed a facilitatory MEP response during the trains in patients evaluated in the preictal phase, whereas inhibitory responses were observed during and after a migraine attack, as well as in CM patients. In the interictal phase, different responses were observed, depending on attack frequency: facilitation in patients with low and inhibition in those with high attack recurrence. Our findings suggest that changes in cortical excitability and fluctuations in the threshold for inhibitory metaplasticity underlie the migraine attack recurrence, and could be involved in the process of migraine transformation.
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The current cross-sectional study examined child and adolescent pain severity in relation to various domains of school functioning and, in line with self-determination theory, the potentially protective role of perceived teacher support of child/adolescent autonomy and competence. Data from a large representative sample of Flemish school children and adolescents (N=10650; 50.8% boys; age range 10-21years; mean age=14.33) was collected as part of the World Health Organization (WHO) collaborative Health Behaviour in School-Aged Children (HBSC) survey. Child/adolescent pain severity was graded based on a pediatric pain classification system adapted from that of Von Korff et al. ⋯ However, the association between pain grade and school absenteeism was less pronounced when children perceived their teachers to be highly supportive of competence and autonomy. Furthermore, teacher support of competence appeared to buffer against the harmful effects of severe pain upon instances of bullying experiences at school. Future research directions and implications for school-based interventions are discussed.
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Case Reports
Nerve resection, crush and re-location relieves complex regional pain syndrome type II: a case report.
This case report describes the remarkable recovery of a patient with very long-standing, medically intractable and disabling, lower-limb, complex regional pain syndrome type II following the resection, crushing, and relocation of sensory nerves.
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While raised levels of monocyte chemoattractant protein 1 (MCP-1) have been observed in patients with chronic muscle pain, direct evidence for its role as an algogen in skeletal muscle is still lacking. In the rat, MCP-1 induces a dose-dependent mechanical hyperalgesia lasting for up to 6weeks. Following recovery, rats exhibited a markedly prolonged hyperalgesia to an intramuscular injection of prostaglandin E2, hyperalgesic priming. ⋯ The AS treatment attenuated this hyperalgesia, whereas IB4-saporin abolished water-avoidance stress-induced muscle hyperalgesia and prevented stress-induced hyperalgesic priming. These results indicate that MCP-1 induces persistent muscle hyperalgesia and a state of latent chronic sensitization to other algogens, by action on its cognate receptor on IB4+ nociceptors. Because MCP-1 also contributes to stress-induced widespread chronic muscle pain, it should be considered as a player in chronic musculoskeletal pain syndromes.
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PI3-kinases (PI3Ks) participate in nociception within spinal cord, dorsal root ganglion (DRG), and peripheral nerves. To extend our knowledge, we immunohistochemically stained for each of the 4 class I PI3K isoforms along with several cell-specific markers within the lumbar spinal cord, DRG, and sciatic nerve of naive rats. Intrathecal and intraplantar isoform specific antagonists were given as pretreatments before intraplantar carrageenan; pain behavior was then assessed over time. ⋯ Intraplantar administration of the γ-antagonist prominently reduced pain behavior. These data suggest that each isoform displays specificity with regard to neuronal type as well as to specific tissues. Furthermore, each PI3K isoform has a unique role in development of nociception and tissue inflammation.