Changes in Intrinsic Connectivity Networks Topology Across Levels of Dexmedetomidine-Induced Alteration of Consciousness.

BACKGROUND: Human consciousness is generally thought to emerge from the activity of intrinsic connectivity networks (resting-state networks [RSNs]) of the brain, which have topological characteristics including, among others, graph strength and efficiency. So far, most functional brain imaging studies in anesthetized subjects have compared wakefulness and unresponsiveness, a state considered as corresponding to unconsciousness. Sedation and general anesthesia not only produce unconsciousness but also phenomenological states of preserved mental content and perception of the environment (connected consciousness), and preserved mental content but no perception of the environment (disconnected consciousness). Unresponsiveness may be seen during unconsciousness, but also during disconnectedness. Deep dexmedetomidine sedation is frequently a state of disconnected consciousness. In this study, we were interested in characterizing the RSN topology changes across 4 different and steady-state levels of dexmedetomidine-induced alteration of consciousness, namely baseline (Awake, drug-free state), Mild sedation (drowsy, still responding), Deep sedation (unresponsive), and Recovery, with a focus on changes occurring between a connected consciousness state and an unresponsiveness state. METHODS: A functional magnetic resonance imaging database acquired in 14 healthy volunteers receiving dexmedetomidine sedation was analyzed using a method combining independent component analysis and graph theory, specifically looking at changes in connectivity strength and efficiency occurring during the 4 above-mentioned dexmedetomidine-induced altered consciousness states. RESULTS: Dexmedetomidine sedation preserves RSN architecture. Unresponsiveness during dexmedetomidine sedation is mainly characterized by a between-networks graph strength alteration and within-network efficiency alteration of lower-order sensory RSNs, while graph strength and efficiency in higher-order RSNs are relatively preserved. CONCLUSIONS: The differential dexmedetomidine-induced RSN topological changes evidenced in this study may be the signature of inadequate processing of sensory information by lower-order RSNs, and of altered communication between lower-order and higher-order networks, while the latter remain functional. If replicated in an experimental paradigm distinguishing, in unresponsive subjects, disconnected consciousness from unconsciousness, such changes would sustain the hypothesis that disconnected consciousness arises from altered information handling by lower-order sensory networks and altered communication between lower-order and higher-order networks, while the preservation of higher-order networks functioning allows for an internally generated mental content (or dream).

[Fibromyalgia, where are we in 2023 ?] / Fibromyalgie, où en est-on en 2023 ?

Fibromyalgia remains a nebulous clinical entity for many practitioners. Actually, this pathology associates diffuse chronic pain with a host of somatic complaints, which may be variable from one patient to another. The difficulty resides also in establishing the diagnosis, which remains essentially clinical, in the absence of anatomical lesions, as well as biological or anatomopathological anomalies. Patients are usually confronted to a therapeutic wandering phase, of variable duration, before being recognized in their pathology. Management of fibromyalgia has to be multimodal, including physiotherapy, a cognitive-behavioural approach, and an individually tailored medical support.

La fibromyalgie reste une entité clinique nébuleuse dans l'esprit de nombreux praticiens. En effet, cette pathologie associe douleurs chroniques diffuses à une multitude de symptômes tels que des troubles du sommeil, des troubles cognitifs, ainsi que de nombreuses plaintes somatiques variables d'un patient à l'autre. La difficulté réside également dans l'établissement du diagnostic. Celui-ci reste avant tout clinique, en l'absence de lésions anatomiques, d'anomalies biologiques ou anatomo-pathologiques. Les patients passent, généralement, par une phase plus ou moins longue d'errance thérapeutique avant d'avoir une reconnaissance de leur pathologie. La prise en charge doit être multimodale, incluant une revalidation en kinésithérapie, une thérapie cognitivo-comportementale, et un accompagnement médical adapté au cas par cas.

Virtual reality hypnosis prior to radiofrequency thermocoagulation for patients with chronic pain: an exploratory clinical trial.

Background: The management of chronic pain may involve an array of tools, including radiofrequency thermocoagulation (Rf-Tc) of sensory nerve terminals. Like many other invasive procedures, Rf-Tc can generate anxiety in a lot of patients, either during the expectation of the procedure or in the course of it. Virtual reality hypnosis (VRH) is a promising tool for managing anxiety and pain in several situations, but its anxiolytic property has not been investigated in participants with chronic pain and going through a Rf-Tc procedure. Objectives: The goal of this study was to evaluate the effectiveness of VRH for reducing self-assessed anxiety in participants with chronic pain, when received in preparation for Rf-Tc. Materials and methods: This prospective, controlled trial was conducted in the Interdisciplinary Algology Centre of the University Hospital of Liège (Belgium). Participants were assigned to two groups: VRH or control (usual care). Assessment was carried-out at 4 time points: T0 (one week before Rf-Tc); T1 (pre-intervention, on the day of Rf-Tc); T2 (immediately after the VRH intervention outside of the Rf-Tc room); and T3 (right after Rf-Tc). Medical, sociodemographic data, anxiety trait and immersive tendencies were collected at T0. Anxiety state and pain intensity were assessed at each time points. Satisfaction was examined at T3. Results: Forty-two participants were quasi-randomly assigned to the VRH or control group. No statistically significant interaction group by time was observed regarding all measured variables, including primary endpoint. However, a significant effect of time was found for anxiety and pain when considering both groups together, toward a progressive reduction. Conclusion: In the context of our study, there appears to be no significant effect of VRH at reducing anxiety in participants with chronic pain undergoing Rf-Tc. Anxiety decreases along the procedure, while pain is attenuated by the local anesthetic infiltration of the Rf site. Our results suggest that the presence of a caregiver throughout the procedure might explain the progressive decrease in anxiety. Future randomized controlled trials are needed to precisely study the effectiveness of the VRH tool, and the possibility of using it as a complementary approach for anxiety during invasive procedures.

The nature of consciousness in anaesthesia.

Neuroscientists agree on the value of locating the source of consciousness within the brain. Anaesthesiologists are no exception, and have their own operational definition of consciousness based on phenomenological observations during anaesthesia. The full functional correlates of consciousness are yet to be precisely identified, however rapidly evolving progress in this scientific domain has yielded several theories that attempt to model the generation of consciousness. They have received variable support from experimental observations, including those involving anaesthesia and its ability to reversibly modulate different aspects of consciousness. Aside from the interest in a better understanding of the mechanisms of consciousness, exploring the functional tenets of the phenomenological consciousness states of general anaesthesia has the potential to ultimately improve patient management. It could facilitate the design of specific monitoring devices and approaches, aiming at reliably detecting each of the possible states of consciousness during an anaesthetic procedure, including total absence of mental content (unconsciousness), and internal awareness (sensation of self and internal thoughts) with or without conscious perception of the environment (connected or disconnected consciousness, respectively). Indeed, it must be noted that unresponsiveness is not sufficient to infer absence of connectedness or even absence of consciousness. This narrative review presents the current knowledge in this field from a system-level, underlining the contribution of anaesthesia studies in supporting theories of consciousness, and proposing directions for future research.

Complementary treatment comparison for chronic pain management: A randomized longitudinal study.

BACKGROUND: In chronic pain, it seems that the effect of cognitive-behavioral therapy (CBT) is boosted when it is combined with hypnosis. The aim of this study was to assess the efficacy of self-hypnosis combined with self-care (i.e., a type of CBT) compared to music/self-care, self-care and psychoeducation/CBT and to evaluate their long-term effects. METHODS: An open label randomized clinical trial enrolled patients with chronic pain and was carried out at the University Hospital of Liège (Belgium). Patients were randomized into four groups: self-hypnosis/self-care, music/self-care, self-care, psychoeducation/CBT (7 monthly sessions of 2 hours). Two follow-up sessions were delivered at 6- and 12-month. Levels of pain, fatigue intensity, anxiety, depression, insomnia severity, disability, health locus of control, mental and physical quality of life and attitudes (control, disability, harm, emotion, medical cure, medication, solicitude) towards pain were assessed before and after the treatments, and at follow-up. RESULTS: 203 patients were randomized: 52 in self-hypnosis/self-care, 59 in music/self-care, 47 in self-care, and 45 in psychoeducation/CBT. No group effect was found. A significant time effect was showed. Directly after the treatment, all groups decreased in pain attitudes and physical quality of life. Perceived control increased. At 6-month, all patients kept their levels of physical quality of life and perceived control, and showed decrease in pain intensity, harm, emotion and medical cure. At 12-month, scores that had change previously remained ameliorated, a decrease in insomnia severity and an increase in internal locus of control were observed. CONCLUSIONS: The present findings are encouraging as they display long-term beneficial effects of complementary biopsychosocial-based treatments in chronic pain. It seems that patients continued to apply the learnt strategies as improvements were observed one year after the treatments had ended.

General Anesthesia: A Probe to Explore Consciousness.

General anesthesia reversibly alters consciousness, without shutting down the brain globally. Depending on the anesthetic agent and dose, it may produce different consciousness states including a complete absence of subjective experience (unconsciousness), a conscious experience without perception of the environment (disconnected consciousness, like during dreaming), or episodes of oriented consciousness with awareness of the environment (connected consciousness). Each consciousness state may potentially be followed by explicit or implicit memories after the procedure. In this respect, anesthesia can be considered as a proxy to explore consciousness. During the recent years, progress in the exploration of brain function has allowed a better understanding of the neural correlates of consciousness, and of their alterations during anesthesia. Several changes in functional and effective between-region brain connectivity, consciousness network topology, and spatio-temporal dynamics of between-region interactions have been evidenced during anesthesia. Despite a set of effects that are common to many anesthetic agents, it is still uneasy to draw a comprehensive picture of the precise cascades during general anesthesia. Several questions remain unsolved, including the exact identification of the neural substrate of consciousness and its components, the detection of specific consciousness states in unresponsive patients and their associated memory processes, the processing of sensory information during anesthesia, the pharmacodynamic interactions between anesthetic agents, the direction-dependent hysteresis phenomenon during the transitions between consciousness states, the mechanisms of cognitive alterations that follow an anesthetic procedure, the identification of an eventual unitary mechanism of anesthesia-induced alteration of consciousness, the relationship between network effects and the biochemical or sleep-wake cycle targets of anesthetic agents, as well as the vast between-studies variations in dose and administration mode, leading to difficulties in between-studies comparisons. In this narrative review, we draw the picture of the current state of knowledge in anesthesia-induced unconsciousness, from insights gathered on propofol, halogenated vapors, ketamine, dexmedetomidine, benzodiazepines and xenon. We also describe how anesthesia can help understanding consciousness, we develop the above-mentioned unresolved questions, and propose tracks for future research.