Recent advances in functional neuroimaging have demonstrated novel potential for informing diagnosis and prognosis in the unresponsive wakeful syndrome and minimally conscious states. However, these technologies come with considerable expense and difficulty, limiting the possibility of wider clinical application in patients. Here, we show that high density electroencephalography, collected from 104 patients measured at rest, can provide valuable information about brain connectivity that correlates with behaviour and functional neuroimaging. Using graph theory, we visualize and quantify spectral connectivity estimated from electroencephalography as a dense brain network. Our findings demonstrate that key quantitative metrics of these networks correlate with the continuum of behavioural recovery in patients, ranging from those diagnosed as unresponsive, through those who have emerged from minimally conscious, to the fully conscious locked-in syndrome. In particular, a network metric indexing the presence of densely interconnected central hubs of connectivity discriminated behavioural consciousness with accuracy comparable to that achieved by expert assessment with positron emission tomography. We also show that this metric correlates strongly with brain metabolism. Further, with classification analysis, we predict the behavioural diagnosis, brain metabolism and 1-year clinical outcome of individual patients. Finally, we demonstrate that assessments of brain networks show robust connectivity in patients diagnosed as unresponsive by clinical consensus, but later rediagnosed as minimally conscious with the Coma Recovery Scale-Revised. Classification analysis of their brain network identified each of these misdiagnosed patients as minimally conscious, corroborating their behavioural diagnoses. If deployed at the bedside in the clinical context, such network measurements could complement systematic behavioural assessment and help reduce the high misdiagnosis rate reported in these patients. These metrics could also identify patients in whom further assessment is warranted using neuroimaging or conventional clinical evaluation. Finally, by providing objective characterization of states of consciousness, repeated assessments of network metrics could help track individual patients longitudinally, and also assess their neural responses to therapeutic and pharmacological interventions.

Different behavioural signs of consciousness can distinguish patients with an unresponsive wakefulness syndrome from patients in minimally conscious state (MCS). The Coma Recovery Scale-Revised (CRS-R) is the most sensitive scale to differentiate the different altered states of consciousness and eleven items detect the MCS. The aim of this study is to document the prevalence of these items. We analysed behavioural assessments of 282 patients diagnosed in MCS based on the CRS-R. Results showed that some items are particularly frequent among patients in MCS, namely fixation, visual pursuit, and reproducible movement to command, which were observed in more than 50% of patients. These responses were also the most probably observed items when the patients only showed one sign of consciousness. On the other hand, some items were rarely or never observed alone, e.g., object localisation (reaching), object manipulation, intelligible verbalisation, and object recognition. The results also showed that limiting the CRS-R assessment to the five most frequently observed items (i.e., fixation, visual pursuit, reproducible movement to command, automatic motor response and localisation to noxious stimulation) detected 99% of the patients in MCS. If clinicians have only limited time to assess patients with disorders of consciousness, we suggest to evaluate at least these five items of the CRS-R.

The Coma Recovery Scale-Revised (CRS-R) is the gold standard to assess severely brain-injured patients with prolonged disorders of consciousness (DoC). However, the amount of time needed to complete this examination may limit its use in clinical settings. We aimed to validate a new faster tool to assess consciousness in individuals with DoC. This prospective validation study introduces the Simplified Evaluation of CONsciousness Disorders (SECONDs), a tool composed of 8 items: arousal, localization to pain, visual fixation, visual pursuit, oriented behaviors, command-following, and communication (both intentional and functional). A total of 57 individuals with DoC were assessed on 2 consecutive days by 3 blinded examiners: one CRS-R and one SECONDs were performed on 1 day, whereas 2 SECONDs were performed on the other day. A Mann-Whitney U test was used to compare the duration of administration of the SECONDs versus the CRS-R, and weighted Fleiss' kappa coefficients were used to assess inter-/intra-rater reliability as well as concurrent validity. In the 57 participants, the SECONDs was about 2.5 times faster to administer than the CRS-R. The comparison of the CRS-R versus the SECONDs on the same day or the best of the 3 SECONDs led to "substantial" or "almost perfect" agreement (kappa coefficients ranging from 0.78 to 0.85). Intra-/inter-rater reliability also showed almost perfect agreement (kappa coefficients from 0.85 to 0.91 and 0.82 to 0.85, respectively). The SECONDs appears to be a fast, reliable and easy-to-use scale to diagnose DoC and may be a good alternative to other scales in clinical settings where time constraints preclude a more thorough assessment.

Near-death experiences (NDEs) are usually associated with positive affect, however, a small proportion are considered distressing. We aimed to look into the proportion of distressing NDEs in a sample of NDE narratives, categorise distressing narratives according to Greyson and Bush’s classification (inverse, void or hellish), and compare distressing and “classical” NDEs. Participants wrote down their experience, completed the Memory Characteristics Questionnaire (assessing the phenomenology of memories) and the Greyson scale (characterising content of NDEs). The proportion of suicidal attempts, content and intensity of distressing and classical NDEs were compared using frequentist and Bayesian statistics. Distressing NDEs represent 14% of our sample (n = 123). We identified 8 inverse, 8 hellish and 1 void accounts. The proportion of suicide survivors is higher in distressing NDEs as compared to classical ones. Finally, memories of distressing NDEs appear as phenomenologically detailed as classical ones. Distressing NDEs deserve careful consideration to ensure their integration into experiencers’ identity.

Patients in unresponsive wakefulness syndrome (UWS e recov- ery of eyes opening while no behavioral sign of consciousness [1]) and in minimally conscious state (MCS e recovery of reproducible purposeful behaviors [2]) have no access to conventional rehabili- tation program, apart from pharmacological or passive rehabilita- tion treatments. A few clinical controlled trials using transcranial direct current stimulation (tDCS) applied over the prefrontal cortex have shown promising results in patients in MCS [3e5]. tDCS has the advantage of being safe and easily performed at patient's bed- sides [6]. In the present study, we decided to stimulate the posterior parietal cortex in subacute and chronic patients in MCS since, based on the literature, it is a critical hub for consciousness recovery (for a review see Ref. [7]). We hypothesized that, by increasing the excit- ability of this critical region, patients might recover some signs of consciousness