Sensory Stimulation Threshold: A Viable Tool to Improve the Outcome of Lumbar Facet Radiofrequency Denervation?

BACKGROUND: Sensory stimulation threshold (SST) has been used as a surrogate marker to target a nerve branch for radiofrequency (RF) denervation; however, the validity of SST as a prognostic marker is still under debate. OBJECTIVE: To assess whether lower SST values correlate with better outcomes of radiofrequency denervation for facetogenic low back pain. DESIGN: Prospective cohort study. PATIENTS: Sixty-seven patients who underwent radiofrequency denervation for low back pain. METHODS: Correlations, between the average percentage of pain relief from diagnostic medial branch block (MBB) and RF denervation procedure outcome, and between SST and RF denervation procedure outcome, were analyzed using Spearman correlation coefficient (rs ). Wilcoxon rank sum test was performed to assess whether magnitude and duration of pain relief following RF denervation differed by the levels of SST (<0.5 and ≥0.5) or pain relief (<80% and ≥80%) from diagnostic MBB. RESULTS: There was a positive correlation between pain relief after diagnostic MBB and pain relief 2 weeks after denervation (rs 0.31, 95% CI 0.08 to 0.51, p < 0.01), but not between pain relief after MBB and pain relief 6 months after denervation, nor pain relief duration after denervation. There was a negative correlation between SST and pain relief 6 months after denervation (rs -0.41, 95% CI -0.59 to -0.18, p < 0.001). There was also a negative correlation between SST and pain relief duration after denervation (rs -0.33, 95% CI -0.53 to -0.09, p < 0.01). CONCLUSION: SST is a viable measurement with which to guide needle placement during RF denervation for lumbar facet pain, and enhances pain relief outcomes.

Electrical Grounding Improves Vagal Tone in Preterm Infants.

BACKGROUND: Low vagal tone (VT) is a marker of vulnerability to stress and the risk of developing necrotizing enterocolitis in preterm infants. Electric fields produced by equipment in the neonatal intensive care unit (NICU) induce an electric potential measurable on the skin in reference to ground. An electrical connection to ground reduces the skin potential and improves VT in adults. OBJECTIVES: We aimed to measure the electric field strengths in the NICU environment and to determine if connecting an infant to electrical ground would reduce the skin potential and improve VT. We also wished to determine if the skin potential correlated with VT. METHODS: Environmental magnetic flux density (MFD) was measured in and around incubators. Electrical grounding (EG) was achieved with a patch electrode and wire that extended to a ground outlet. We measured the skin potential in 26 infants and heart rate variability in 20 infants before, during, and after grounding. VT was represented by the high-frequency power of heart rate variability. RESULTS: The background MFD in the NICU was below 0.5 mG, but it ranged between 1.5 and 12.7 mG in the closed incubator. A 60-Hz oscillating potential was recorded on the skin of all infants. With EG, the skin voltage dropped by about 95%. Pre-grounding VT was inversely correlated with the skin potential. VT increased by 67% with EG. After grounding, the VT fell to the pre-grounding level. CONCLUSION: The electrical environment affects autonomic balance. EG improves VT and may improve resilience to stress and lower the risk of neonatal morbidity in preterm infants.

Chemotherapeutic drugs and human tumor cells cytokine network.

The ability of human tumor cell lines to produce various cytokines, chemokines, angiogenic and growth factors was investigated using Luminex multiplex technology. Media conditioned by tumor cells protected tumor cells from drug-induced apoptosis and stimulated tumor cell proliferation. Antibodies neutralizing IL-6, CXCL8, CCL2 and CCL5 blocked this stimulation. Treatment of tumor cells with doxorubicin and cisplatin resulted in a substantial increase in the production of IL-6, CXCL8, CCL2, CCL5, BFGF, G-CSF and VEGF. This stimulation was associated with drug-induced activation of NF-kappaB, AP-1, AP-2, CREB, HIF-1, STAT-1, STAT-3, STAT-5 and ATF-2 transcription factors and upregulation of IL-6, CXCL8, FGF-2, CSF-3 and CCL5 gene expression. Treatment of tumor cells with doxorubicin and antibodies neutralizing G-CSF, CCL2 or CCL5 had higher inhibitory effects than each modality used alone. These results indicate that chemokines and growth factors produced by tumor by binding to the cognate receptors on tumor and stroma cells could provide proliferative and antiapoptotic signals helping tumor to escape drug-mediated destruction. Clinical studies showed that antibodies neutralizing VEGF (Avastin/Bevacizumab) or blocking HER2/neu signaling (Herceptin/Trastuzumab) could increase the efficacy of chemotherapy, although these beneficial effects have been limited. It is possible that drug-stimulated production of growth and proangiogenic factors could counterbalance the effects of antibody therapy. In addition, numerous growth factors and chemokines share angiogenic and growth-stimulating properties, and thus reduction of a single factor is insufficient to completely block tumor growth. Thus, a broad disruption of tumor cytokine network is needed to further increase the efficacy of cancer therapy.