Toward Improving Diagnostic Strategies in Chronic Disorders of Consciousness: An Overview on the (Re-)Emergent Role of Neurophysiology

Abstract

The differential diagnosis of patients with Disorder of Consciousness (DoC), in particular in the chronic phase, is significantly difficult. Actually, about 40% of patients with unresponsive wakefulness syndrome (UWS) and the minimally conscious state (MCS) are misdiagnosed. Indeed, only advanced paraclinical approaches, including advanced EEG analyses, can allow achieving a more reliable diagnosis, that is, discovering residual traces of awareness in patients with UWS (namely, functional Locked-In Syndrome (fLIS)). These approaches aim at capturing the residual brain network models, at rest or that may be activated in response to relevant stimuli, which may be appropriate for awareness to emerge (despite their insufficiency to generate purposeful motor behaviors). For this, different brain network models have been studied in patients with DoC by using sensory stimuli (i.e., passive tasks), probing response to commands (i.e., active tasks), and during resting-state. Since it can be difficult for patients with DoC to perform even simple active tasks, this scoping review aims at summarizing the current, innovative neurophysiological examination methods in resting state/passive modality to differentiate and prognosticate patients with DoC. We conclude that the electrophysiologically-based diagnostic procedures represent an important resource for diagnosis, prognosis, and, therefore, management of patients with DoC, using advance passive and resting state paradigm analyses for the patients who lie in the “greyzones” between MCS, UWS, and fLIS.

Paths to Oblivion: Common Neural Mechanisms of Anaesthesia and Disorders of Consciousness

“…However, the brain is a paradigmatic example of a complex system 3 , and different perturbations of its precise functioning can serve as a path towards loss of consciousness. Examples of such perturbations range from transient pharmacological (general anaesthetic) interventions having widespread effects on neuromodulation [4][5][6][7] , to chronic disorders of consciousness arising from traumatic or anoxic injuries of diverse location and extent, often including changes to the physical connectivity between brain regions [8][9][10][11][12] .…”

Virtual Reality Based Cognitive Rehabilitation in Minimally Conscious State: A Case Report with EEG Findings and Systematic Literature Review

“…However, the data of our case-report are consistent with those from the studies we reviewed, showing that patient’s responses are not always easily interpretable using clinical scales only. By comparing previous studies regarding the use of other physiological indices and VR, we believe that our approach could be a valid tool to define DoC and reach the differential diagnosis, taking into account that around 40% of patients with UWS and MCS are misdiagnosed in clinical practice [ 76 ]. A quantitative assessment of command-following tasks (as per our combined EEG-VR approach) can be particularly helpful in dealing with differential diagnosis of these patients.…”

Critical Illness Polyneuropathy and Myopathy and Clinical Detection of the Recovery of Consciousness in Severe Acquired Brain Injury Patients with Disorders of Consciousness after Rehabilitation

“…Finally, the use of a multimodal evaluation by combining clinical evaluation and instrumental tools (electroencephalography (EEG), somatosensory-evoked potentials, or functional neuroimaging) is now recommended to improve clinical classification and prognostication of people with DoC [ 37 , 38 ]. Neurophysiological tests, EEGs in particular [ 39 ], have proven to be valuable tools to be used alongside the clinical scale to reduce the risk of misdiagnosis in patients with DoC [ 40 ]; the presence of CIPNM should be a further reason to recommend such assessments. Furthermore, with a diagnosis of CIPNM, the application of complementary diagnostic tools, such as the motor behavior tool, as proposed for the motor/cognitive dissociation [ 29 ], but also the practice of focusing CRS-R motor assessment on facial muscles may help to reduce misdiagnosis.…”