Presse Med
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The 'mesocircuit hypothesis' proposes mechanisms underlying the recovery of consciousness following severe brain injuries. The model builds up from a single premise that multifocal brain injuries resulting in coma and subsequent disorders of consciousness produce widespread neuronal death and dysfunction. Considering the general properties of cortical, thalamic, and striatal neurons, a lawful and specific circuit-level mechanism is constructed based on these known anatomical and physiological specializations of neuronal subtypes. ⋯ Many studies have examined predictions of the mesocircuit model; here we first present the model and review the accumulated evidence for several predictions of model across multiple stages of recovery function in human subjects. Recent studies linking the mesocircuit model, the ABCD model, and interactions with the frontoparietal network are reviewed. Finally, theoretical implications of the mesocircuit model at the neuronal level are considered to interpret recent studies of deep brain stimulation in the central lateral thalamus in patients recovering from coma and in new experimental models in the context of emerging understanding of neuronal and local circuit mechanisms underlying conscious brain states.
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Patients with disorders of consciousness (DoC) represent a group of severely brain-injured patients with varying capacities for consciousness in terms of both wakefulness and awareness. The current state-of-the-art for assessing these patients is through standardised behavioural examinations, but inaccuracies are commonplace. Neuroimaging and electrophysiological techniques have revealed vast insights into the relationships between neural alterations, andcognitive and behavioural features of consciousness in patients with DoC. ⋯ Instead, for consciousness to arise, we need preserved thalamo-cortical circuits, in addition to sufficient connectivity between distinctly differentiated brain networks, underlined by connectivity both within, and between such brain networks. Finally, we present recent advances and future perspectives in computational methodologies applied to DoC, supporting the notion that progress in the science of DoC will be driven by a symbiosis of these data-driven analyses, and theory-driven research. Both perspectives will work in tandem to provide mechanistic insights contextualised within theoretical frameworks which ultimately inform the practice of clinical neurology.
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This manuscript explores the international variability in the diagnosis and management of disorders of consciousness (DoC). The identification, evaluation, intervention, exploration, prognostication and limitation of therapy for patients with DoC is reviewed through an international lens. The myriad factors that impact the diagnosis and management of DoC including 1) financial, 2) legal and regulatory, 3) cultural, 4) religious and 5) psychosocial considerations are discussed. ⋯ It is necessary to promote equity in access to expertise and resources for patients with DoC to enhance the care of patients with DoC worldwide. Improving understanding and management of patients with DoC requires harmonization of existing datasets, development of registries where none exist and establishment of international clinical trial networks that include patients in all phases along the spectrum of care. The work of international organizations like the Curing Coma Campaign can hopefully minimize international variability in the diagnosis and management of DoC and optimize care.
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Several methods have been proposed to foster recovery of consciousness in patients with disorders of consciousness (DoC). ⋯ Personalised sensory stimulation, median nerve stimulation, transcranial direct current stimulation (tDCS), amantadine and zolpidem all have favourable risk-benefit ratios and are easy to implement in clinical practice. These treatments should be proposed to every patient with chronic DoC. Comprehensive patient management should also include regular lifting, pain assessment and treatment, attempts to restore sleep and circadian rhythms, implementation of rest periods, comfort and nursing care, and a rehabilitation program with a multi-disciplinary team with expertise in this field. More invasive treatments may cause adverse effects and require further investigation to confirm preliminary, encouraging results and to better define responders' intervention parameters. Scientific studies are essential and given the severity of the disability and handicap that results from DoC, research in this area should aim to develop new therapeutic approaches.