Pain
-
Review Meta Analysis Guideline
Interventional management of neuropathic pain: NeuPSIG recommendations.
After reviewing available evidence the Neuropathic Pain Special Interest Group could only recommend:
- Epidural injections for herpes zoster neuropathic pain.
- Steroid injections for radiculopathy.
- Spinal cord stimulator for failed back surgery syndrome or Complex Regional Pain Syndrome type 1
-
Endogenous TRPV1 agonists such as oxidized linoleic acid metabolites (OLAMs) and the enzymes releasing them [eg, cytochrome P450 (CYP)] are up-regulated after inflammation in the rat. However, it is not known whether such agonists are elevated in human inflammatory pain conditions. Because TRPV1 is expressed in human dental pulp nociceptors, we hypothesized that OLAM-CYP machinery is active in this tissue type and is increased under painful inflammatory conditions such as irreversible pulpitis (IP). ⋯ These data suggest that LA metabolites produced in human inflamed tissues act as TRPV1 agonists and that the metabolite production can be targeted by CYP inhibition. In addition, immunohistochemical analysis of 2 CYP isoforms, CYP2J and CYP3A1, were shown to be predominately expressed in immune cells infiltrating the inflamed dental pulp, emphasizing the paracrine role of CYP enzymes in OLAM regulation. Collectively, our data indicate that the machinery responsible for OLAM production is up-regulated during inflammation and can be targeted to develop potential analgesics for inflammatory-induced dental pain.
-
Human association studies of common genetic polymorphisms have identified many loci that are associated with risk of complex diseases, although individual loci typically have small effects. However, by envisaging genetic associations in terms of cellular pathways, rather than any specific polymorphism, combined effects of many biologically relevant alleles can be detected. The effects are likely to be most apparent in investigations of phenotypically homogenous subtypes of complex diseases. ⋯ A risk index representing combined effects of 6 SNPs from the serotonergic pathway was associated with greater odds of localized TMD (odds ratio 2.7, P=1.3 E-09), and the result was reproduced in a replication case-control cohort study of 639 people (odds ratio 1.6, P=0.014). A risk index representing combined effects of 8 SNPs from the T-cell receptor pathway was associated with greater odds of TMD with widespread pain (P=1.9 E-08), although the result was not significant in the replication cohort. These findings illustrate potential for clinical classification of chronic pain based on distinct molecular profiles and genetic background.
-
The aim of this study was to assess the function of the thermo-nociceptive system in 25 patients with long-lasting, medium-to-severe refractory complex regional pain syndrome (CRPS)-1 using behavioral (detection rates and reaction times) and electrophysiological (event-related brain potentials) responses to brief (50 milliseconds) and intense (suprathreshold for Aδ-nociceptors) carbon dioxide laser stimuli delivered to the affected and contralateral limbs, and by comparing these responses to the responses obtained in the left and right limbs of age- and sex-matched healthy controls. Compared with healthy controls and compared with the contralateral limb, the detection rate of pricking pain related to the activation of Aδ-fibers was markedly reduced at the affected limb. Furthermore, reaction times were substantially prolonged (>100 milliseconds in 84% of patients and >300milliseconds in 50% of patients). ⋯ Taken together, our results show that in the majority of patients with chronic CRPS-1, thermo-nociceptive pathways are dysfunctional. A number of pathological mechanisms involving the peripheral nervous system and/or the central nervous system could explain our results. However, the primary or secondary nature of these observed changes remains an open question.