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Evoked potentials in the amplitude-time spectrum of the electroencephalogram are commonly used to assess the extent of brain responses to stimulation with noxious contact heat. The magnitude of the N- and P-waves are used as a semi-objective measure of the response to the painful stimulus: the higher the magnitude, the more painful the stimulus has been perceived. The strength of the N-P-wave response is also largely dependent on the chosen reference electrode site. The goal of this study was to examine which reference technique excels both in practical and theoretical terms when analyzing noxious contact heat evoked potentials (CHEPS) in the amplitude-time spectrum. We recruited 21 subjects (10 male, 11 female, mean age of 55.79 years). We applied seven noxious contact heat stimuli using two temperatures, 51°C, and 54°C, to each subject. During EEG analysis, we aimed to identify the referencing technique which produces the highest N-wave and P-wave amplitudes with as little artifactual influence as possible. For this purpose, we applied the following six referencing techniques: mathematically linked A1/A2 (earlobes), average reference, REST, AFz, Pz, and mathematically linked PO7/PO8. We evaluated how these techniques impact the N-P amplitudes of CHEPS based on our data from healthy subjects. Considering all factors, we found that mathematically linked earlobes to be the ideal referencing site to use when displaying and evaluating CHEPS in the amplitude-time spectrum.
Objectives: It is known that transition, as a shift of care, marks a vulnerable phase in the adolescents’ lives with an increased risk for non-adherence and allograft failure. Still, the transition process of adolescents and young adults living with a kidney transplant in Germany is not well defined. The present research aims to assess transition-relevant structures for this group of young people. Special attention is paid to the timing of the process.
Setting: In an observational study, we visited 21 departments of paediatric nephrology in Germany. Participants were doctors (n=19), nurses (n=14) and psychosocial staff (n=16) who were responsible for transition in the relevant centres. Structural elements were surveyed using a short questionnaire. The experiential viewpoint was collected by interviews which were transcribedverbatim before thematic analysis was performed.
Results: This study highlights that professionals working within paediatric nephrology in Germany are well aware of the importance of successful transition. Key elements of transitional care are well understood and mutually agreed on. Nonetheless, implementation within daily routine seems challenging, and the absence of written, structured procedures may hamper successful transition.
Conclusions: While professionals aim for an individual timing of transfer based on medical, social, emotional and structural aspects, rigid regulations on transfer age as given by the relevant health authorities add on to the challenge.
Trial registration: number ISRCTN Registry no 22988897; results (phase I) and pre-results (phase II).
Background and objectives: Our study aimed at examining the long-time inflammatory effects of rheumatoid arthritis (RA) as chronic immune-mediated disease on pain sensation and neuropathy development compared to healthy subjects (HS).
Methods: We used the quantitative sensory testing (QST) protocol of the German Research Network on Neuropathic Pain and Electroencephalography (EEG)–based contact heat evoked potentials (CHEPs) before and after topical capsaicin application. We recruited 16 RA patients in remission or low disease activity state (mean age: 59.38 years [± 10.18]) and 16 healthy subjects (mean age: 56.69 years [± 8.92]).
Results: The application of capsaicin cream on the thigh provoked a stronger effect in HS for both mechanical and heat pain thresholds (MPT and HPT, resp.), according to the area under the receiver operation characteristic (AUROC) (HS: HPT: 0.8965, MPT: 0.7402; RA: HPT: 0.7012, MPT: 0.6113). We observed contrary effects regarding changes in CHEPs (HS: g*max = − 0.65; RA patients: g*max = 0.72).
Conclusion: As the overall effect of topical capsaicin application was higher in HS for QST, we suggest the existence of a sensitization of TRPV1 channels in RA patients caused by long-time chronical inflammation, despite a lack of clinical signs of inflammation due to adequate treatment. The effect in CHEPs probably uncovers neuropathic symptoms. The effect of topical capsaicin on HPTs and CHEPs can act as a marker for the extent of sensitization and the development of neuropathic symptoms. Further studies are needed to prove if our proposed method can act as a marker for the success of anti-inflammatory treatment.
Highlights
• During the dying process, surges of higher-frequency activation can be seen in patients with unresponsive coma, raising concerns about possible conscious mental states.
• Parameterization of the power spectrum shows fundamental temporal changes during the last hour of dying.
• In the last minutes before death, parameterized neural activity is still fundamentally unique.
Abstract
Background: Cortical high-frequency activation immediately before death has been reported, raising questions about an enhanced conscious state at this critical time. Here, we analyzed an electroencephalogram (EEG) from a comatose patient during the dying process with a standard bedside monitor and spectral parameterization techniques.
Methods: We report neurophysiologic features of a dying patient without major cortical injury. Sixty minutes of frontal EEG activity was recorded using the Sedline™ monitor. Quantitative metrics of the frequency spectrum, the non-oscillatory 1/f characteristic, and signal complexity with Lemple-Ziv-Welch and permutation entropy were calculated. In addition to comparing the EEG trajectories over time, we provide a comparison to EEG records obtained from other studies with well-known vigilance states (sleep, anesthesia, and wake).
Results: Although we observed changes in high-frequency activation during the dying process, larger alterations of the aperiodic EEG components were also noted. These changes differed dramatically when compared to EEG records representative of wake, slow-wave sleep, or anesthesia. Although still fundamentally unique, the neuronal activity present in the dying brain is more similar to REM sleep than any other state we tested.
Conclusion: Even in patients with coma, temporal dynamics in quantitative EEG features (including the aperiodic components) can be observed in the final hour before death.