Investigating the specificity of the neurologic pain signature against breathlessness and finger opposition

Empathetic solicitude attenuates the affective and sensory dimensions of CO2-induced dyspnea: A randomized parallel arm experimental trial in healthy humans

Dyspnea testifies to profound suffering in patients and its relief is a priority for caregivers. This can be achieved by correcting causative disorders ("etiopathogenic" approach) or targeting the dyspnea itself ("symptomatic" approach), as is done for pain. Empathetic solicitude from caregivers has an intrinsic analgesic effect, but its effects on dyspnea have not been formally documented. This study tests the hypothesis that the empathetic solicitude behavior of a caregiver during experimental induction of acute and intense dyspnea would have a mitigating effect. In a double-blind, randomized, controlled experimental trial, 80 healthy participants were assigned to a neutral behavior arm or a solicitude behavior arm. During two successive visits (V1 and V2), dyspnea was induced through CO2-rebreathing and (i) assessed in an immediate manner using 10 cm affective and sensory visual analog scales (A-VAS and S-VAS) and (ii) post hoc using the Multidimensional Dyspnea Profile (MDP). A-VAS ratings at the end of the dyspnea challenge were significantly lower at V2 in the "solicitude behavior" arm than in the "neutral behavior" arm (6.69 [3.825-9.67] vs. 8.05 [6.43-10], p = 0.039). There were no significant differences between arms regarding S-VAS. MDP analysis showed that CO2-rebreathing induced dyspnea of the air hunger type, with statistically significant reductions in its intensity and both the sensory and affective dimensions of dyspnea. This study shows that empathetic solicitude can reduce the affective and sensory dimensions of experimentally induced dyspnea in healthy volunteers. Future studies should evaluate the impact of empathetic solicitude on clinical dyspnea.

Persistent disabilities 28 months after COVID-19 hospitalisation, a prospective cohort study

Background

Limited data are available on long-term respiratory disabilities in patients following acute COVID-19.

Patients and methods

This prospective, monocentric, observational cohort study included patients admitted to our hospital with acute COVID-19 between 12 March and 24 April 2020. Clinical, functional and radiological data were collected up to 28 months after hospital discharge.

Results

Among 715 patients hospitalised for COVID-19, 493 (69.0%) were discharged alive. We could access complete medical records for 268 out of 493 patients (54.4%); 138 out of 268 (51.5%) exhibited persistent respiratory symptoms and agreed with the data collection and follow-up. Patients were predominantly male (64.5%), with a mean±sd age of 58.9±15.3 years. At the last follow-up, the leading symptoms were asthenia (31.5%), dyspnoea (29.8%) and neuropsychological symptoms (17.7%). Lung function improved up to the last visit. Mean diffusing capacity of the lung for carbon monoxide (D LCO) was 77.8% of predicted value, total lung capacity (TLC) was 83.5% and O2 desaturation during exercise (O2 desaturation) was 2.3%. While D LCO improved over the entire period, TLC improved in the early phase and O2 desaturation in the late phase. Except for those with lung comorbidities, only one patient presented with minor functional and chest radiological alterations at 28 months.

Conclusion

Patients with acute COVID-19 discharged alive showed improved clinical symptoms, lung function parameters and radiological signs up to 28 months post-infection. Persistent symptoms consisted mainly of asthenia and dyspnoea, with lung function returning to normal. One patient without prior respiratory issues exhibited moderate pulmonary fibrosis.

Placebo treatment affects brain systems related to affective and cognitive processes, but not nociceptive pain

Drug treatments for pain often do not outperform placebo, and a better understanding of placebo mechanisms is needed to improve treatment development and clinical practice. In a large-scale fMRI study (N = 392) with pre-registered analyses, we tested whether placebo analgesic treatment modulates nociceptive processes, and whether its effects generalize from conditioned to unconditioned pain modalities. Placebo treatment caused robust analgesia in conditioned thermal pain that generalized to unconditioned mechanical pain. However, placebo did not decrease pain-related fMRI activity in brain measures linked to nociceptive pain, including the Neurologic Pain Signature (NPS) and spinothalamic pathway regions, with strong support for null effects in Bayes Factor analyses. In addition, surprisingly, placebo increased activity in some spinothalamic regions for unconditioned mechanical pain. In contrast, placebo reduced activity in a neuromarker associated with higher-level contributions to pain, the Stimulus Intensity Independent Pain Signature (SIIPS), and affected activity in brain regions related to motivation and value, in both pain modalities. Individual differences in behavioral analgesia were correlated with neural changes in both modalities. Our results indicate that cognitive and affective processes primarily drive placebo analgesia, and show the potential of neuromarkers for separating treatment influences on nociception from influences on evaluative processes.

Placebo treatment affects brain systems related to affective and cognitive processes, but not nociceptive pain

Placebo analgesia is a replicable and well-studied phenomenon, yet it remains unclear to what degree it includes modulation of nociceptive processes. Some studies find effects consistent with nociceptive effects, but meta-analyses show that these effects are often small. We analyzed placebo analgesia in a large fMRI study (N = 392), including placebo effects on brain responses to noxious stimuli. Placebo treatment caused robust analgesia in both conditioned thermal and unconditioned mechanical pain. Placebo did not decrease fMRI activity in nociceptive pain regions, including the Neurologic Pain Signature (NPS) and pre-registered spinothalamic pathway regions, with strong support from Bayes Factor analyses. However, placebo treatment affected activity in pre-registered analyses of a second neuromarker, the Stimulus Intensity Independent Pain Signature (SIIPS), and several associated a priori brain regions related to motivation and value, in both thermal and mechanical pain. Individual differences in behavioral analgesia were correlated with neural changes in both thermal and mechanical pain. Our results indicate that processes related to affective and cognitive aspects of pain primarily drive placebo analgesia.

Breathing control, brain, and bodily self-consciousness: Toward immersive digiceuticals to alleviate respiratory suffering

Breathing is peculiar among autonomic functions through several characteristics. It generates a very rich afferent traffic from an array of structures belonging to the respiratory system to various areas of the brain. It is intimately associated with bodily movements. It bears particular relationships with consciousness as its efferent motor control can be automatic or voluntary. In this review within the scope of "respiratory neurophysiology" or "respiratory neuroscience", we describe the physiological organisation of breathing control. We then review findings linking breathing and bodily self-consciousness through respiratory manipulations using virtual reality (VR). After discussing the currently admitted neurophysiological model for dyspnea, as well as a new Bayesian model applied to breathing control, we propose that visuo-respiratory paradigms -as developed in cognitive neuroscience- will foster insights into some of the basic mechanisms of the human respiratory system and will also lead to the development of immersive VR-based digital health tools (i.e. digiceuticals).

Neuroimaging enters the pain biomarker arena

Neuroimaging methods can be used to identify biomarkers of acute and chronic pain.