Attrition with spinal cord stimulation

The aim of this prospective study was to investigate whether spinal cord stimulation (SCS) significantly reduces pain intensity for up to 18-month follow-up in patients with chronic neuropathic pain. Forty-eight patients were recruited. Patients rated their pain using a Visual analog scale (VAS) and pain-related disability using the Oswestry Disability Index (ODI) at baseline (1 week prior to SCS surgery) and at 6-, 12-, and 18-month follow-up. Pain intensity significantly decreased from baseline to all 3 time points [F (3,135) = 16.264, p < 0.001]. The greatest difference in the reduction of pain intensity was observed between baseline (M = 7.20, SD = 1.34) and 6-month follow-up (M = 4.60, SD = 2.20), [t(47) = 6.741, p < 0.001]. However, when looking at differences between the 6-month follow-up and subsequent assessments, statistically significant increases in pain intensity from the 6-month to the 12-month follow-up [t(47) = -2.788, p = 0.008], and from the 6-month to the 18-month follow-up [t(47) = -3.339, p = 0.002] could be observed. Statistically significant changes were also observed for clinical changes in pain scores [F (2,94) = 4.972, p = 0.009. There was a significant decrease in the percentage of clinical change obtained from the 6-month (M = 33.19, SD = 35.63) to the 12-month follow-up (M = 23.76, SD = 33.62), [t(47) = 2.347, p = 0.025], and from the 6-month to the 18-month follow-up (M = 18.34, SD = 33.51), [t(47) = 3.072, p = 0.004]. A number of patients also reported higher levels of pain intensity at the 12-and 18-month follow-up than at baseline.Pain-related disability scores significantly decreased from baseline (M = 55.04, SD = 16.43) to the 6-month follow up (M = 46.98, SD = 19.05), [t(47) = 3.464, p = 0.001] and from baseline to the 12-month follow up (M = 48.49, SD = 20.94), [t(47) = 2.918, p = 0.005], but not during the 18-month follow up (M = 51.75, SD = 20.92), [t(47) = 1.330, p =.190]. There was a significant increase in pain-related disability between the 6- and the 18-month follow up [t(47) = -2.188. p = 0.034]. These findings suggest that the beneficial effect of SCS on pain intensity may diminish over time, and that the 6-month follow-up scores may reflect a placebo effect. © 2015 The Neurosurgical Foundation

Analysis of psychological characteristics impacting spinal cord stimulation treatment outcomes:a prospective assessment

Background: Psychological factors are recognised as influencing the outcome of spinal cord stimulation (SCS) although there is currently no consensus as to which factors impact upon SCS efficacy. Objective: To identify psychological characteristics that may impact the efficacy of SCS. Study Design: Prospective evaluation. Setting: Single secondary care center in Dudley, United Kingdom. Methods: Patients: Seventy-five patients were initially recruited and 56 patients (31 women and 25 men) were followed-up for 12-months. Intervention: SCS for the management of chronic non-cancer pain. Main Outcome Measures: Outcome measures assessed at baseline, 6 months, and 12 months following SCS implantation included the visual analogue scale (VAS), Oswestry disability index (ODI), hospital anxiety and depression (HAD) scale, and the pain coping strategies questionnaire (PCSQ). Results: Statistically significant improvements were observed for the VAS (P < 0.001), ODI (P = 0.011), anxiety (P = 0.042), and depression (P = 0.010) in the HAD scale and for the subscales reinterpreting pain sensation (P = 0.018), control over pain (P = 0.001), and ability to decrease pain (P < 0.001) of the PCSQ. We observed that depression and autonomous coping (control over pain, ability to reduce pain, and catastrophizing) may impact sensory aspects such as pain intensity and disability scores affecting the outcome of SCS treatment. Age at time of implant and duration of pain prior to implant were also found to impact SCS efficacy. Limitations: It has been reported that loss of analgesia may be experienced within 12 to 24 months following SCS implantation and therefore, it would be of interest to follow patients over a longer period. Conclusions: This study demonstrates that psychological aspects such as depression and autonomous coping may impact SCS treatment. Addressing these issues prior to SCS implantation may improve SCS long-term outcome. © 2015, American Society of Interventional Pain Physicians. All Rights Reserved

Pair Creation of Dilaton Black Holes in Extended Inflation

Dilatonic Charged Nariai instantons mediate the nucleation of black hole pairs during extended chaotic inflation. Depending on the dilaton and inflaton fields, the black holes are described by one of two approximations in the Lorentzian regime. For each case we find Euclidean solutions that satisfy the no boundary proposal. The complex initial values of the dilaton and inflaton are determined, and the pair creation rate is calculated from the Euclidean action. Similar to standard inflation, black holes are abundantly produced near the Planck boundary, but highly suppressed later on. An unusual feature we find is that the earlier in inflation that the dilatonic black holes are created, the more highly charged they can be.Comment: 23 pages, LaTeX, 6 figures; submitted to Phys. Rev.

Charged Nariai Black Holes With a Dilaton

The Reissner-Nordstrom-de Sitter black holes of standard Einstein-Maxwell theory with a cosmological constant have no analogue in dilatonic theories with a Liouville potential. The only exception are the solutions of maximal mass, the Charged Nariai solutions. We show that the structure of the solution space of the Dilatonic Charged Nariai black holes is quite different from the non-dilatonic case. Its dimensionality depends on the exponential coupling constants of the dilaton. We discuss the possibility of pair creating such black holes on a suitable background. We find conditions for the existence of Charged Nariai solutions in theories with general dilaton potentials, and consider specifically a massive dilaton.Comment: 20 pages, LaTeX, 4 figures, submitted to Phys. Rev.

Pair Creation of Black Holes During Inflation

Black holes came into existence together with the universe through the quantum process of pair creation in the inflationary era. We present the instantons responsible for this process and calculate the pair creation rate from the no boundary proposal for the wave function of the universe. We find that this proposal leads to physically sensible results, which fit in with other descriptions of pair creation, while the tunnelling proposal makes unphysical predictions. We then describe how the pair created black holes evolve during inflation. In the classical solution, they grow with the horizon scale during the slow roll-down of the inflaton field; this is shown to correspond to the flux of field energy across the horizon according to the First Law of black hole mechanics. When quantum effects are taken into account, however, it is found that most black holes evaporate before the end of inflation. Finally, we consider the pair creation of magnetically charged black holes, which cannot evaporate. In standard Einstein-Maxwell theory we find that their number in the presently observable universe is exponentially small. We speculate how this conclusion may change if dilatonic theories are applied.Comment: 29 pages, LaTeX, 3 figures, submitted to Phys. Rev. D; minor typos corrected, missing minus sign in Eq. (3.11) inserte

QT interval dynamics in patients with ST-elevation MI

BackgroundAn association between excessively prolonged QT and ventricular arrhythmia in patients with ST-elevation myocardial infarction has been described; however, the QT dynamics, characterization, and long-term predictive value are not well known.ObjectiveTo characterize QT interval dynamics in patients undergoing ST elevation myocardial infarction (STEMI) and determine its association with mortality.MethodsA retrospective analysis of 4,936 consecutive patients, hospitalized for STEMI between 01/2013–12/2021. Patients with less than three electrocardiograms (ECGs) during index hospitalization were excluded. Baseline demographics, cardiovascular history, clinical risk factors, treatment measures, laboratory results, and mortality data were retrieved from the hospital’s electronic medical records.ResultsWe included 1,054 patients and 5,021 ECGs in our cohort with a median follow-up of 6 years [interquartile range (IQR) 4.3–7.4 years]. The QT was longer in women in comparison to men (428.6 ms ± 33.4 versus 419.8 ms ± 32.52, P-value = 0.001). QT prolongation was greater in females, elderly patients, and patients with STEMI caused by occlusion of the left anterior descending (LAD) coronary artery. We determined QT cutoff to be 445 ms. This value of QT divided our cohort upon arrival into a long QT group (217 patients, 26% of the cohort) and a “normal” QT group (835 patients, 74% of the cohort). The long QT group experienced an increase in combined short and long terms all-cause mortality. The QT upon arrival, on day 2 of hospitalization, and before discharge from the hospital, correlated with long-term mortality.ConclusionQT duration is often prolonged during STEMI; this prolongation is associated with increased mortality and adverse events. Gender is an important mediator of QT dynamics

Quantum Global Structure of de Sitter Space

I study the global structure of de Sitter space in the semi-classical and one-loop approximations to quantum gravity. The creation and evaporation of neutral black holes causes the fragmentation of de Sitter space into disconnected daughter universes. If the black holes are stabilized by a charge, I find that the decay leads to a necklace of de Sitter universes (`beads') joined by near-extremal black hole throats. For sufficient charge, more and more beads keep forming on the necklace, so that an unbounded number of universes will be produced. In any case, future infinity will not be connected. This may have implications for a holographic description of quantum gravity in de Sitter space.Comment: 37 pages, LaTeX2e, 10 figures. v2: references adde