Pain Mechanisms and Treatments (19)
Pancreatic and Hepatic Oncology Research (19)
Neuroendocrine Tumor Research Advances (13)
Botulinum Toxin and Related Neurological Disorders (13)
Anesthesia and Pain Management (12)
Lee JU, Ma JE, Sartori Valinotti JC, Rooke TW, Sandroni P , et al.
Vascular medicine (London, England) •
Erythromelalgia is a rare disorder characterized by episodic burning pain with redness and warmth of the extremities. Topical and systemic medications are the mainstay of management. We reviewed the published evidence for using procedural interventions to manage erythromelalgia, including their proposed mechanism of action and possible adverse effects, and included information in this review on epidural infusion, sympathetic ganglion block, sympathectomy, pulsed radiofrequency, spinal cord stimulation, dorsal root ganglion stimulation, brain stimulation, transcranial magnetic stimulation, and botulinum toxin injections. Both successful and unsuccessful outcomes have been reported. Although these procedural interventions extend the therapeutic options for erythromelalgia, the evidence for their use is limited. Case reports and small case series comprise most of the evidence. Based on our review, a multidisciplinary approach to management may be needed for patients with erythromelalgia.
Pagani-Estévez GL, Sandroni P, Davis MD, Watson JC
Journal of the American Academy of Dermatology •
Corticosteroids (CS) may benefit certain patients with erythromelalgia. Our objective was to determine clinical predictors of corticosteroid-responsive erythromelalgia. Patients with erythromelalgia who received CS were identified and stratified into corticosteroid nonresponders (NRs), partial corticosteroid responders (PSRs), complete corticosteroid responders (CSRs), and steroid responders (SRs = PSRs + CSRs). In the study variable analysis, P < .05 was considered statistically significant. The median (interquartile range) age of the 31-patient cohort was 47 years (26-57 years), and 22 (71%) were female. Fourteen (45%) were NRs, 17 (55%) SRs, 8 (26%) PSRs, and 9 (29%) CSRs. A subacute temporal profile to disease zenith (<21 days) was described in 15 (48%) patients, of whom 13 (87%) were SRs (P = .003; odds ratio [OR] = 0.069 [95% confidence interval {CI}, 0.011-0.431]). Six (67%) CSRs reported a disease precipitant (eg, surgery, trauma, or infection; P = .007; OR = 12.667 [95% CI, 2-80.142]). SR patients received CS sooner than NR at 3 (3-12) versus 24 (17-45) months (P = .003). A high-dose CS trial (≥200 mg prednisone cumulatively) was administered to 17 (55%) patients, of whom 13 (76%) were SRs (P = .012; OR = 8.125 [95% CI, 1.612-40.752]). This was a retrospective case series. An infectious, traumatic, or surgical precipitant and subacute presentation may portend CR erythromelalgia. A transient "golden window" where CS intervention is useful may exist before irreversible nociceptive remodeling and central sensitization occurs.
Fouillet A, Watson JF, Piekarz AD, Huang X, Li B , et al.
Molecular pain •
Background The Na1.7 subtype of voltage-gated sodium channels is specifically expressed in sensory and sympathetic ganglia neurons where it plays an important role in the generation and transmission of information related to pain sensation. Human loss or gain-of-function mutations in the gene encoding Na1.7 channels (SCN9A) are associated with either absence of pain, as reported for congenital insensitivity to pain, or with exacerbation of pain, as reported for primary erythromelalgia and paroxysmal extreme pain disorder. Based on this important human genetic evidence, numerous drug discovery efforts are ongoing in search for Nav1.7 blockers as a novel therapeutic strategy to treat pain conditions. Results We are reporting here a novel approach to study Na1.7 function in cultured rat sensory neurons. We used live cell imaging combined with electrical field stimulation to evoke and record action potential-driven calcium transients in the neurons. We have shown that the tarantula venom peptide Protoxin-II, a known Na1.7 subtype selective blocker, inhibited electrical field stimulation-evoked calcium responses in dorsal root ganglia neurons with an IC of 72 nM, while it had no activity in embryonic hippocampal neurons. The results obtained in the live cell imaging assay were supported by patch-clamp studies as well as by quantitative PCR and Western blotting experiments that confirmed the presence of Na1.7 mRNA and protein in dorsal root ganglia but not in embryonic hippocampal neurons. Conclusions The findings presented here point to a selective effect of Protoxin-II in sensory neurons and helped to validate a new method for investigating and comparing Na1.7 pharmacology in sensory versus central nervous system neurons. This will help in the characterisation of the selectivity of novel Na1.7 modulators using native ion channels and will provide the basis for the development of higher throughput models for enabling pain-relevant phenotypic screening.