European Academy of Neurology guideline on the diagnosis of coma and other disorders of consciousness

Caring for Coma after Severe Brain Injury: Clinical Practices and Challenges to Improve Outcomes: An Initiative by the Curing Coma Campaign

Severe brain injury can result in disorders of consciousness (DoC), including coma, vegetative state/unresponsive wakefulness syndrome, and minimally conscious state. Improved emergency and trauma medicine response, in addition to expanding efforts to prevent premature withdrawal of life-sustaining treatment, has led to an increased number of patients with prolonged DoC. High-quality bedside care of patients with DoC is key to improving long-term functional outcomes. However, there is a paucity of DoC-specific evidence guiding clinicians on efficacious bedside care that can promote medical stability and recovery of consciousness. This Viewpoint describes the state of current DoC bedside care and identifies knowledge and practice gaps related to patient care with DoC collated by the Care of the Patient in Coma scientific workgroup as part of the Neurocritical Care Society's Curing Coma Campaign. The gap analysis identified and organized domains of bedside care that could affect patient outcomes: clinical expertise, assessment and monitoring, timing of intervention, technology, family engagement, cultural considerations, systems of care, and transition to the post-acute continuum. Finally, this Viewpoint recommends future research and education initiatives to address and improve the care of patients with DoC.

The Pupillary Light-Off Reflex in Acute Disorders of Consciousness

BACKGROUND

In intensive care patients with disorders of consciousness, the pupillary light reflex is a measure of pupillary parasympathetic function. By contrast, the pupillary light-off reflex leads to pupil dilation in response to an abrupt change from light to darkness ("light-off") and reflects combined parasympathetic and sympathetic pupillary function. To our knowledge, this reflex has not been systematically investigated in patients with disorders of consciousness. We hypothesized that the pupillary light-off reflex correlates with consciousness levels after acute brain injury.

METHODS

From November 2022 to March 2023, we enrolled 100 study participants: 25 clinically unresponsive (coma or unresponsive wakefulness syndrome) and 25 clinically low-responsive (minimally conscious state or better) patients from the intensive care units of a tertiary referral center, and 50 age-matched and sex-matched healthy controls. Exclusion criteria were active or chronic eye disease. We used automated pupillometry to assess the pupillary light-off reflex and the pupillary light reflex of both eyes under scotopic conditions in all study participants.

RESULTS

The pupillary light-off reflex was strongly correlated with consciousness levels (r = 0.62, p < 0.001), the increase in pupillary diameters being smallest in unresponsive patients (mean ± standard deviation 20% ± 21%), followed by low-responsive patients (mean ± standard deviation 47% ± 26%) and healthy controls (mean ± standard deviation 67% ± 17%; p < 0.001). Similar yet less pronounced patterns were observed for the pupillary light reflex. Twenty-one of 25 (84%) unresponsive patients had preserved pupillary light reflexes, but only seven (28%) had fully preserved pupillary light-off reflexes (p < 0.0001). Of these 7 patients, five (71%) regained awareness.

CONCLUSIONS

The pupillary light-off reflex may be more sensitive to consciousness levels than the pupillary light reflex. The clinical implications of this finding seem worthy of further investigation, particularly regarding possible benefits for neuromonitoring and prognostication after brain injury.

Care pathways for individuals with post-anoxic disorder of consciousness (CaPIADoC): an inter-society Consensus Conference

BACKGROUND

Accurate recognition of consciousness level and detection of neurological complications since the intensive care unit are crucial for an appropriate prognostication and tailored treatment in patients with post-anoxic disorder of consciousness (DoC).

OBJECTIVE

The present inter-society Consensus Conference aimed at addressing current debates on diagnostic and prognostic procedures.

METHODS

Twelve working groups involving 22 multidisciplinary professionals (membership of 9 Scientific Societies and 2 patients' family Associations) conducted a systematic literature review focused on 12 questions addressing diagnosis (n = 5) and prognosis (n = 7). The quality of evidence of the included studies was evaluated using the Oxford Centre for Evidence-Based Medicine Levels of Evidence. A Jury involving Scientific Societies and patients' family Associations provided recommendations based on the evidence levels and expert opinion.

RESULTS

An overall number of 1,219 papers was screened, and 21 were included in the review. Working groups produced a report on strengths and limits of evidence for each question. The overall suggestion was to use a multimodal assessment combining validated clinical scales, neurophysiological exams, and neuroimaging in diagnostic and prognostic procedure, to guide personalized treatment. A strong recommendation was to use standardized terminologies and diagnostic criteria for ensuring homogeneity and appropriateness in patients management.

CONCLUSION

This multidisciplinary Consensus Conference provided the first operational recommendations for a good clinical practice procedure for patients with post-anoxic DoC. A periodic review will be necessary based on future evidence from the literature and implementation of the present recommendations.

Repetitive transcranial magnetic stimulation frequency influences the hemodynamic responses in patients with disorders of consciousness

Repetitive transcranial magnetic stimulation (rTMS) emerges as a promising non-invasive neuromodulation technique for the treatment of patients with disorders of consciousness (DOC). The selection of rTMS parameters significantly influences the clinical therapeutic effects. However, the differences in spatiotemporal responsiveness of the brain under different rTMS stimulation frequencies remain unclear. In this pilot study, functional near-infrared spectroscopy (fNIRS) was used to evaluate the spatiotemporal differences in hemodynamic responses elicited by rTMS at different frequencies (1, 5, 10, 15, and 20 Hz) over left dorsolateral prefrontal cortex (F3). The results showed that the distribution patterns of the rTMS-evoked hemodynamic responses varied across different frequencies, indicating that rTMS frequency influences the hemodynamic responses in patients with DOC. Specifically, 10 Hz rTMS evoked strong positive hemodynamic responses over the frontal cortex, particularly in the right dorsolateral prefrontal cortex (R-DLPFC). Additionally, 20 Hz rTMS produced largepositive hemodynamic responses over the motor-related cortex, especially the right premotor cortex (R-PreM) and right primary sensorimotor cortex (PSMC). The current findings suggested that fNIRS can be used as a promising tool for evaluating the effects of rTMS in patients with DOC. Moreover, it provides useful guidance for the personalized design of rTMS parameters in a clinical environment.

Impact of Aphasia on Brain Activation to Motor Commands in Patients with Acute Intracerebral Hemorrhage

BACKGROUND

Brain activation to motor commands is seen in 15% of clinically unresponsive patients with acute brain injury. This state called cognitive motor dissociation (CMD) is detectable by electroencephalogram (EEG) or functional magnetic resonance imaging, predicts long-term recovery, and is recommended by recent guidelines to support prognostication. However, false negative CMD results are a particular concern, and occult aphasia in clinically unresponsive patients may be a major factor. This study aimed to quantify the impact of aphasia on CMD testing.

METHODS

We prospectively studied 61 intensive care unit patients admitted with acute primary intracerebral hemorrhage (ICH) who had behavioral evidence of command following or were able to mimic motor commands. All patients underwent an EEG-based motor command paradigm used to detect CMD and comprehensive aphasia assessments. Logistic regression was used to identify predictors of brain activation, including aphasia types and associations with recovery of independence (Glasgow Outcome Scale-Extended score ≥ 4).

RESULTS

Of 61 patients, 50 completed aphasia and the EEG-based motor command paradigm. A total of 72% (n = 36) were diagnosed with aphasia. Patients with impaired comprehension (i.e., receptive or global aphasia) were less likely to show brain activation than those with intact comprehension (odds ratio [OR] 0.23 [95% confidence interval 0.05-0.89], p = 0.04). Brain activation was independently associated with Glasgow Outcome Scale-Extended ≥ 4 by 12 months (OR 2.4 [95% confidence interval 1.2-5.0], p = 0.01) accounting for the Functional Outcome in Patients with Primary ICH score (OR1.3 [95% confidence interval 1.0-1.8], p = 0.01).

CONCLUSIONS

Brain activation to motor commands is four times less likely for patients with primary ICH with impaired comprehension. False negative results due to occult receptive aphasia need to be considered when interpreting CMD testing. Early detection of brain activation may help predict long-term recovery in conscious patients with ICH.

Management of severe acute encephalopathy in the ICU: an expert consensus statement from the french society of intensive care medicine

INTRODUCTION

Acute encephalopathy in the ICU poses significant diagnostic, therapeutic, and prognostic challenges. Standardized expert guidelines on acute encephalopathy are needed to improve diagnostic methods, therapeutic decisions, and prognostication.

METHODS

The experts conducted a review of the literature, analysed it according to the GRADE (Grading of Recommendation, Assessment, Development and Evaluation) methodology and made proposals for guidelines, which were rated by other experts. Only expert opinions with strong agreement were selected.

RESULTS

The synthesis of expert work and the application of the GRADE method resulted in 39 recommendations. Among the 39 formalized recommendations, 1 had a high level of evidence (GRADE 1 +) and 10 had a low level of evidence (GRADE 2 + or 2-). These recommendations describe indication for ICU admission, use of clinical scores and EEG for diagnosis, detection of complications, and prognostication. The remaining 28 recommendations were based on expert consensus. These recomandations describe common indications for blood and CSF studies, neuroimaging, use of neuromonitoring, and provide guidelines for management in the acute phase.

CONCLUSION

This expert consensus statement aims to provide a structured framework to enhance the consistency and quality of care for ICU patients presenting with acute encephalopathy. By integrating high-quality evidence with expert opinion, it offers a pragmatic approach to addressing the complex nature of acute encephalopathy in the ICU, promoting best practices in patient care and facilitating future research in the field.

Acute biomarkers of consciousness are associated with recovery after severe traumatic brain injury

Objective

Determine whether acute behavioral, electroencephalography (EEG), and functional MRI (fMRI) biomarkers of consciousness are associated with outcome after severe traumatic brain injury (TBI).

Methods

Patients with acute severe TBI admitted consecutively to the intensive care unit (ICU) participated in a multimodal battery assessing behavioral level of consciousness (Coma Recovery Scale-Revised [CRS-R]), cognitive motor dissociation (CMD; task-based EEG and fMRI), covert cortical processing (CCP; stimulus-based EEG and fMRI), and default mode network connectivity (DMN; resting-state fMRI). The primary outcome was 6-month Disability Rating Scale (DRS) total scores.

Results

We enrolled 55 patients with acute severe TBI. Six-month outcome was available in 45 (45.2±20.7 years old, 70% male), of whom 10 died, all due to withdrawal of life-sustaining treatment (WLST). Behavioral level of consciousness and presence of command-following in the ICU were each associated with lower (i.e., better) DRS scores (p=0.003, p=0.011). EEG and fMRI biomarkers did not strengthen this relationship, but higher DMN connectivity was associated with better recovery on multiple secondary outcome measures. In a subsample of participants without command-following on the CRS-R, CMD (EEG:18%; fMRI:33%) and CCP (EEG:91%; fMRI:79%) were not associated with outcome, an unexpected result that may reflect the high rate of WLST. However, higher DMN connectivity was associated with lower DRS scores (ρ[95%CI]=-0.41[-0.707, -0.027]; p=0.046) in this group.

Interpretation

Standardized behavioral assessment in the ICU may improve prediction of recovery from severe TBI. Further research is required to determine whether integrating behavioral, EEG, and fMRI biomarkers of consciousness is more predictive than behavioral assessment alone.

Influencing factors of hospitalization costs for intensive rehabilitation in patients with post-stroke disorder of consciousness

Objective

In China, patients requiring intensive rehabilitation often face a gap between acute treatment and sub-acute rehabilitation. This study evaluates the composition and determinants of post-acute hospitalization costs in stroke patients with disorders of consciousness (DoC).

Methods

Data from 133 stroke patients with DoC who underwent inpatient rehabilitation at a tertiary hospital from 2015 to 2020 were collected, including demographic characteristics, clinical features, and hospitalization costs. Descriptive statistical analysis and univariate analysis were performed, followed by path analysis and Bootstrap mediation tests to explore factors influencing hospitalization costs.

Results

The median hospitalization costs were $56,860.80. Rehabilitation costs accounted for the largest proportion of total hospitalization costs (36.55%). Direct factors influencing total costs included payment method, admission to the intensive care unit (ICU), pulmonary infection, and length of stay (LOS) (p < 0.05). The effect sizes ranked in descending order were LOS, ICU experience, payment method, and pulmonary infection. Bootstrap mediation tests revealed significant mediation effects (p < 0.05) of payment method, occupation, patient origin, hypertension, ICU experience, and death on total costs, indicating that these factors indirectly influenced costs by affecting LOS.

Conclusion

Greater attention should be given to meeting the rehabilitation needs of patients by expanding resources for intensive rehabilitation and ensuring continuous rehabilitation services. Comprehensive and effective measures should be implemented to address cost-influencing factors early, without compromising the quality of care.

Preliminaries to artificial consciousness: A multidimensional heuristic approach

The pursuit of artificial consciousness requires conceptual clarity to navigate its theoretical and empirical challenges. This paper introduces a composite, multilevel, and multidimensional model of consciousness as a heuristic framework to guide research in this field. Consciousness is treated as a complex phenomenon, with distinct constituents and dimensions that can be operationalized for study and for evaluating their replication. We argue that this model provides a balanced approach to artificial consciousness research by avoiding binary thinking (e.g., conscious vs. non-conscious) and offering a structured basis for testable hypotheses. To illustrate its utility, we focus on "awareness" as a case study, demonstrating how specific dimensions of consciousness can be pragmatically analyzed and targeted for potential artificial instantiation. By breaking down the conceptual intricacies of consciousness and aligning them with practical research goals, this paper lays the groundwork for a robust strategy to advance the scientific and technical understanding of artificial consciousness.

Magnetic resonance imaging in traumatic brain injury: a survey of clinical practitioners' experiences and views on current practice and obstacles

INTRODUCTION

Magnetic resonance imaging (MRI) has revolutionized our capacity to examine brain alterations in traumatic brain injury (TBI). However, little is known about the level of implementation of MRI techniques in clinical practice in TBI and associated obstacles.

METHODS

A diverse set of health professionals completed 19 multiple choice and free text survey questions.

RESULTS

Of the 81 respondents, 73.4% reported that they acquire/order MRI scans in TBI patients, and 66% indicated they would prefer MRI be more often used with this cohort. The greatest impediment for MRI usage was scanner availability (57.1%). Less than half of respondents (42.1%) indicated that they perform advanced MRI analysis. Factors such as dedicated experts within the team (44.4%) and user-friendly MRI analysis tools (40.7%), were listed as potentially helpful to implement advanced MRI analyses in clinical practice.

CONCLUSION

Results suggest a wide variability in the purpose, timing, and composition of the scanning protocol of clinical MRI after TBI. Three recommendations are described to broaden implementation of MRI in clinical practice in TBI: 1) development of a standardized multimodal MRI protocol; 2) future directions for the use of advanced MRI analyses; 3) use of low-field MRI to overcome technical/practical issues with high-field MRI.

Abnormal characteristics in disorders of consciousness: A resting-state functional magnetic resonance imaging study

AIMS

To explore the functional brain imaging characteristics of patients with disorders of consciousness (DoC).

METHODS

This prospective cohort study consecutively enrolled 27 patients in minimally conscious state (MCS), 23 in vegetative state (VS), and 25 age-matched healthy controls (HC). Resting-state functional magnetic resonance imaging (rs-fMRI) was employed to evaluate the amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), degree centrality (DC), and functional connectivity (FC). Sliding windows approach was conducted to construct dynamic FC (dFC) matrices. Moreover, receiver operating characteristic analysis and Pearson correlation were used to distinguish these altered characteristics in DoC.

RESULTS

Both MCS and VS exhibited lower ALFF, ReHo, and DC values, along with reduced FC in multiple brain regions compared with HC. Furthermore, the values in certain regions of VS were lower than those in MCS. The primary differences in brain function between patients with varying levels of consciousness were evident in the cortico-striatopallidal-thalamo-cortical mesocircuit. Significant differences in the temporal properties of dFC (including frequency, mean dwell time, number of transitions, and transition probability) were also noted among the three groups. Moreover, these multimodal alterations demonstrated high classificatory accuracy (AUC > 0.8) and were correlated with the Coma Recovery Scale-Revised (CRS-R).

CONCLUSION

Patients with DoC displayed abnormal patterns in local and global dynamic and static brain functions. These alterations in rs-fMRI were closely related to the level of consciousness.

Reconstructing Covert Consciousness: Neural Decoding as a Novel Consciousness Assessment

Determining the level of consciousness in patients with brain injury-and more fundamentally, establishing what they can experience-is ethically and clinically impactful. Patient behaviors may unreliably reflect their level of consciousness: a subset of unresponsive patients demonstrate covert consciousness by willfully modulating their brain activity to commands through fMRI or EEG. However, current paradigms for assessing covert consciousness remain fundamentally limited because they are insensitive, rely on imperfect assumptions of functional neuroanatomy, and do not reflect the spectrum of conscious experience. Neural decoding, in which stimuli and concepts are reconstructed from brain activity, offers a novel approach to covert consciousness assessment that overcomes many of these limitations. In this article, we discuss the current state of covert consciousness assessments, their shortcomings, the state of the science in neural decoding, the potential application of neural decoding to disorders of consciousness, and future directions that may help realize this potential. To do so, we searched PubMed and Google Scholar databases for pertinent articles published between January 1990 and September 2024, using the search terms "covert consciousness," "cognitive motor dissociation," "neural decoding," and "semantic decoding." Redefining covert consciousness with neural decoding may improve sensitivity, enhance granularity, and more directly address the question of what patients can experience after brain injury.

Making Healthcare Decisions on Behalf of People in a Disorder of Consciousness. A "Risk-Making" Theory of Decisional Practices

Healthcare decisions evaluate treatment risks and benefits, using a shared decision-making process between patient and clinician. Healthcare workers (HCWs) offer treatments based on condition specific evidence and expert knowledge. The patient evaluates treatment choices from their individual perception of how helpful or harmful treatment might be. This is a "risk-taking" decision. Those in a disorder of consciousness (DOC) have unreliable or absent awareness. They cannot participate in the risk-taking decisional process outlined above. Instead, family members and HCWs evaluate the options and determine how much risk is acceptable. We propose this is a distinctly different decisional process called "risk-making," and that for those in a DOC it is influenced by multiple poorly understood factors. The different ways that decisions are made on their behalf may be negatively impacting their healthcare and creating a distributive justice need. A "risk-making" theory of DOC healthcare decision-making was developed via narrative literature review. It aims to explicate the realities of DOC decision-making practices, and surface rarely discussed assumptions and social factors possibly impacting DOC healthcare for discussion and future exploration.

Electroencephalographic differences between waking and sleeping periods in patients with prolonged disorders of consciousness at different levels of consciousness

Objective

This study aimed to explore differences in sleep electroencephalogram (EEG) patterns in individuals with prolonged disorders of consciousness, utilizing polysomnography (PSG) to assist in distinguishing between the vegetative state (VS)/unresponsive wakefulness syndrome (UWS) and the minimally conscious state (MCS), thereby reducing misdiagnosis rates and enhancing the quality of medical treatment.

Methods

A total of 40 patients with prolonged disorders of consciousness (pDOC; 27 patients in the VS/UWS and 13 in the MCS) underwent polysomnography. We analyzed differential EEG indices between VS/UWS and MCS groups and performed correlation analyses between these indices and the Coma Recovery Scale-Revised (CRS-R) scores. The diagnostic accuracy of the differential indices was evaluated using receiver operating characteristic (ROC) curves.

Results

1. The fractal dimension (Higuchi's fractal dimension (HFD)) of patients in the MCS tended to be higher than that of patients in the VS/UWS across all phases, with a significant difference only in the waking phase (p < 0.05). The HFD in the waking phase was positively correlated with the CRS-R score and exhibited the highest diagnostic accuracy at 88.3%. The Teager-Kaiser energy operator (TKEO) also showed higher levels in patients in the MCS compared to those in the VS/UWS, significantly so in the NREM2 phase (p < 0.05), with a positive correlation with the CRS-R score and diagnostic accuracy of 75.2%. The δ-band power spectral density [PSD(δ)] in the patients in the MCS was lower than that in those in the VS/UWS, significantly so in the waking phase (p < 0.05), and it was negatively correlated with the CRS-R score, with diagnostic accuracy of 71.5%.

Conclusion

Polysomnography for the VS/UWS and MCS revealed significant differences, aiding in distinguishing between the two patient categories and reducing misdiagnosis rates. Notably, the HFD and PSD(δ) showed significantly better performance during wakefulness compared to sleep, while the TKEO was more prominent in the NREM2 stage. Notably, the HFD exhibited a robust correlation with the CRS-R scores, the highest diagnostic accuracy, and immense promise in the clinical diagnosis of prolonged disorders of consciousness.

Impacts of long-term nasogastric tube feeding and tracheostomy on pharyngeal and laryngeal structure in ABI patients: an FEES study

OBJECTIVES

To investigate the characteristics of pharyngeal and laryngeal structure in patients with acquired brain injury (ABI), who were long time wearing nasogastric tube (NGT) with or without tracheostomy.

METHODS

103 ABI patients with NGT indwelled for more than 1 month were retrospectively studied and divided into two groups by whether or not undergoing tracheostomy. Age, gender, types of brain injury, course of the disease, disorders of consciousness, activities of daily living (ADL) and fiberoptic endoscopic examination of swallowing (FEES) were evaluated. The structure and function of pharyngeal and laryngeal were assessed by FEES, focusing on the morphology of the arytenoid cartilage, epiglottis, vocal folds, tongue base, and pharyngeal cavity.

RESULTS

Prolonged indwelling nasogastric tubes and tracheostomy tubes might lead to abnormal alterations of the structure and function in the arytenoid cartilage, epiglottis, tongue base, and pharyngeal cavity. Epiglottis shape abnormality, glossoptosis and pharyngeal stenosis were present in a larger proportion of the NGT-TRACH (nasogastric tube with tracheostomy) group than the NGT group (p < 0.05).

CONCLUSIONS

This study highlights potential physiological changes associated with prolonged placement of nasogastric tubes and tracheostomy tubes, which could impede the recovery of swallowing function and decannulation. We hope to provide valuable evidence to develop effective management strategies for ABI patients with NGT or tracheostomy.

A Review of Advances in Multimodal Treatment Strategies for Chronic Disorders of Consciousness Following Severe Traumatic Brain Injury

Background

Chronic disorders of consciousness (cDoC) resulting from severe traumatic brain injury (sTBI) are associated with significant challenges in treatment and recovery. This review explores multimodal interventions aimed at improving patient outcomes.

Methods

A systematic review was conducted on peer-reviewed studies from PubMed and Google Scholar published between 2000 and 2023. The review included clinical trials, observational studies, and case series that assessed interventions for improving consciousness and cognitive function in patients with cDoC following sTBI. Interventions considered included pharmacological treatments, non-invasive neuromodulation, rehabilitation therapies, and traditional medicine approaches.

Results

The review identifies several promising interventions. Hyperbaric oxygen therapy (HBOT), when combined with physical rehabilitation and non-invasive brain stimulation techniques like transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), has shown positive effects on consciousness and cognitive recovery. Non-invasive neuromodulation techniques have been linked to improvements in cortical activity and consciousness, with taVNS emerging as a novel approach. Additionally, traditional Chinese medicine, particularly herbal therapies, has demonstrated complementary benefits when integrated with modern rehabilitation methods. Personalized treatment strategies based on clinical characteristics, biomarkers, and genetic data were found to enhance recovery. Notably, integrating these modalities into personalized care protocols has shown enhanced efficacy, suggesting that individualized approaches are critical for improving outcomes.

Conclusion

Multimodal therapies show promise in enhancing recovery in cDoC patients after sTBI, but further research is needed to optimize treatment protocols and standardize clinical practices. The integration of traditional and modern therapies represents a potentially effective strategy for improving patient outcomes.

Cross-cultural adaptation and multicentric validation of the Italian version of the Simplified Evaluation of CONsciousness Disorders (SECONDs)

INTRODUCTION

The Coma Recovery Scale-Revised (CRS-R) is the recommended tool to assess consciousness in patients with prolonged Disorders of Consciousness (pDoC). However, the time needed to administer it may limit its use. A shorter tool has been validated: the Simplified Evaluation of CONsciousness Disorders (SECONDs). This multicentre study aimed to develop and validate a cross-cultural adaptation of the SECONDs into Italian.

METHODS

An interdisciplinary expert team, from both Fondazione Don Carlo Gnocchi and Istituto Neurologico Carlo Besta, led the translation processes. Independent certified translators were also involved in a blinded modality. Patients diagnosed with Unresponsive Wakefulness Syndrome (UWS) or Minimally Conscious State (MCS) admitted to 3 Italian rehabilitation units were enrolled. The CRS-R and SECONDs were administered in 5 sessions over two weeks by 3 blinded examiners at each center (3 times, with 2 sessions conducted by the same examiner). Weighted Fleiss' kappa and Spearman correlation coefficients were used to assess intrarater and interrater reliability and concurrent validity.

RESULTS

Sixty adults with pDoC were assessed: 23 women; median age: 64 years; 14 trauma, median post-onset time: 2 months. Intrarater and interrater reliability showed almost perfect agreement (kappa coefficients 0.968 and 0.935, respectively; p<0.001). The comparison of CRS-R vs. SECONDs on the same day or the best out of 5 SECONDs/CRS-R led to a substantial to almost perfect agreement both for the total score of the CRS-R and the SECONDs' Additional Index (ρ = 0.772-1.000; p<0.001) and for the consciousness diagnosis (k = 0.784-0.935; p<0.001). The disagreement rate between the overall best diagnosis of the SECONDs and the best CRS-R diagnosis was 6.7%.

CONCLUSION

The Italian version of the SECONDs has been cross-culturally adapted to serve as a shorter assessment tool for the diagnosis of pDoC. Our study shows its excellent reliability and concurrent validity when compared to the CRS-R.

Case report: Monitoring consciousness with fNIRS in a patient with prolonged reduced consciousness following hemorrhagic stroke undergoing adjunct taVNS therapy

Disorders of consciousness (DoC) resulting from severe brain injury present substantial challenges in rehabilitation due to disruptions in brain network connectivity, particularly within the frontal-parietal network critical for awareness. Transcutaneous auricular vagus nerve stimulation (taVNS) has emerged as a promising non-invasive intervention; however, the precise mechanisms through which it influences cortical function in DoC patients remain unclear. This study describes the effects of taVNS on fronto-parietal network connectivity and arousal in a 77-year-old female patient with unresponsive wakefulness syndrome (UWS). The patient received bilateral taVNS for 1 h daily over 3 months, with functional connectivity (FC) in the frontoparietal network assessed using functional near-infrared spectroscopy (fNIRS) and behavioral responsiveness evaluated through the Coma Recovery Scale-Revised (CRS-R). After taVNS intervention, mean FC was enhanced from 0.06 (SD = 0.31) to 0.33 (SD = 0.28) in the frontal-parietal network. The frontal-parietal were subdivided into 12 regions of interest (ROIs) and it was determined that the FC between the left dorsolateral prefrontal cortex (DLPFC) and the left prefrontal ROIs was 0.06 ± 0.41 before the intervention and 0.55 ± 0.24 after the intervention. Behavioral improvements were evidenced by an increase in CRS-R scores from 2 to 14, marking the patient's transition from UWS to minimally conscious state plus (MCS+). Additionally, regions associated with auditory and sensory processing showed increased cortical engagement, supporting the positive impact of taVNS on cortical responsiveness. This suggests its value as a non-invasive adjunctive therapy in the rehabilitation of DoC patients. Further studies are necessary to confirm these effects in a wider patient population and to refine the strategy for clinical application of taVNS.

Functional near-infrared spectroscopy for the assessment and treatment of patients with disorders of consciousness

Background

Advances in neuroimaging have significantly enhanced our understanding of brain function, providing critical insights into the diagnosis and management of disorders of consciousness (DoC). Functional near-infrared spectroscopy (fNIRS), with its real-time, portable, and noninvasive imaging capabilities, has emerged as a promising tool for evaluating functional brain activity and nonrecovery potential in DoC patients. This review explores the current applications of fNIRS in DoC research, identifies its limitations, and proposes future directions to optimize its clinical utility.

Aim

This review examines the clinical application of fNIRS in monitoring DoC. Specifically, it investigates the potential value of combining fNIRS with brain-computer interfaces (BCIs) and closed-loop neuromodulation systems for patients with DoC, aiming to elucidate mechanisms that promote neurological recovery.

Methods

A systematic analysis was conducted on 155 studies published between January 1993 and October 2024, retrieved from the Web of Science Core Collection database.

Results

Analysis of 21 eligible studies on neurological diseases involving 262 DoC patients revealed significant findings. The prefrontal cortex was the most frequently targeted brain region. fNIRS has proven crucial in assessing brain functional connectivity and activation, facilitating the diagnosis of DoC. Furthermore, fNIRS plays a pivotal role in diagnosis and treatment through its application in neuromodulation techniques such as deep brain stimulation (DBS) and spinal cord stimulation (SCS).

Conclusion

As a noninvasive, portable, and real-time neuroimaging tool, fNIRS holds significant promise for advancing the assessment and treatment of DoC. Despite limitations such as low spatial resolution and the need for standardized protocols, fNIRS has demonstrated its utility in evaluating residual brain activity, detecting covert consciousness, and monitoring therapeutic interventions. In addition to assessing consciousness levels, fNIRS offers unique advantages in tracking hemodynamic changes associated with neuroregulatory treatments, including DBS and SCS. By providing real-time feedback on cortical activation, fNIRS facilitates optimizing therapeutic strategies and supports individualized treatment planning. Continued research addressing its technical and methodological challenges will further establish fNIRS as an indispensable tool in the diagnosis, prognosis, and treatment monitoring of DoC patients.

Comprehensive evaluation and diagnosis of persistent vegetative state after hypoxic-ischemic encephalopathy: a case report

We report a case of a 39-year-old woman with persistent vegetative state (PVS) following cardiac arrest and a right lower extremity fracture. Despite comprehensive rehabilitation for over 4 months, there was no improvement. Neuroelectrophysiological and neuroimaging assessments showed poor brain function, and the coma recovery scale-revised scale results suggested low arousal probability. Furthermore, patients with PVS exhibit autonomic reactivity and physiological responses to external stimuli. It is important to note that while these reactions may manifest as responsiveness to external stimuli, they should be interpreted as automatic physiological responses rather than indicative of consciousness.

A Multimodal Consistency-Based Self-Supervised Contrastive Learning Framework for Automated Sleep Staging in Patients With Disorders of Consciousness

Sleep is a fundamental human activity, and automated sleep staging holds considerable investigational potential. Despite numerous deep learning methods proposed for sleep staging that exhibit notable performance, several challenges remain unresolved, including inadequate representation and generalization capabilities, limitations in multimodal feature extraction, the scarcity of labeled data, and the restricted practical application for patients with disorder of consciousness (DOC). This paper proposes MultiConsSleepNet, a multimodal consistency-based sleep staging network. This network comprises a unimodal feature extractor and a multimodal consistency feature extractor, aiming to explore universal representations of electroencephalograms (EEGs) and electrooculograms (EOGs) and extract the consistency of intra- and intermodal features. Additionally, self-supervised contrastive learning strategies are designed for unimodal and multimodal consistency learning to address the current situation in clinical practice where it is difficult to obtain high-quality labeled data but has a huge amount of unlabeled data. It can effectively alleviate the model's dependence on labeled data, and improve the model's generalizability for effective migration to DOC patients. Experimental results on three publicly available datasets demonstrate that MultiConsSleepNet achieves state-of-the-art performance in sleep staging with limited labeled data and effectively utilizes unlabeled data, enhancing its practical applicability. Furthermore, the proposed model yields promising results on a self-collected DOC dataset, offering a novel perspective for sleep staging research in patients with DOC.

Predicting Long-Term Outcome of Prolonged Disorder of Consciousness in Children Through Machine Learning Based on Conventional Structural Magnetic Resonance Imaging

BACKGROUND

The prognosis of prolonged disorders of consciousness (pDoC) in children has consistently posed a formidable challenge in clinical decision-making.

OBJECTIVE

This study aimed to develop a machine learning (ML) model based on conventional structural magnetic resonance imaging (csMRI) to predict outcomes in children with pDoC.

METHODS

A total of 196 children with pDoC were included in this study. Based on the consciousness states 1 year after brain injury, the children were categorized into either the favorable prognosis group or the poor prognosis group. They were then randomly assigned to the training set (n = 138) or the test set (n = 58). Semi-quantitative visual assessments of brain csMRI were conducted and Least Absolute Shrinkage and Selection Operator regression was used to identify significant features predicting outcomes. Based on the selected features, support vector machine (SVM), random forests (RF), and logistic regression (LR) were used to develop csMRI, clinical, and csMRI-clinical-merge models, respectively. Finally, the performances of all models were evaluated.

RESULTS

Seven csMRI features and 4 clinical features were identified as important predictors of consciousness recovery. All models achieved satisfactory prognostic performances (all areas under the curve [AUCs] >0.70). Notably, the csMRI model developed using the SVM exhibited the best performance, with an AUC, accuracy, sensitivity, and specificity of 0.851, 0.845, 0.844, and 0.846, respectively.

CONCLUSIONS

A csMRI-based prediction model for the prognosis of children with pDoC was developed, showing potential to predict recovery of consciousness 1 year after brain injury and is worth popularizing in clinical practice.

Consciousness trajectories and functional independence after acute brain injury in children with prolonged disorder of consciousness

AIM

To explore the trajectories of consciousness recovery and prognosis-associated predictors in children with prolonged disorder of consciousness (pDoC).

METHOD

This single-centre, retrospective, observational cohort involved 134 (87 males, 47 females) children diagnosed with pDoC and hospitalized at the Department of Rehabilitation at the Children's Hospital of Chongqing Medical University in China. The median onset age was 30 (interquartile range [IQR] 18-54) months, with onset ages ranging from 3 to 164 months. Least absolute shrinkage and selection operator (LASSO) regression and logistic regression analyses were performed to identify the independent predictors of consciousness recovery at 1 year after brain injury. Discrimination and calibration were assessed using 1000 bootstrap resamples. The potential predictors of resultant living independence were also explored.

RESULTS

The predictors for consciousness recovery at 1-year postinjury were: traumatic brain injury (odds ratio [OR]: 3.26, 95% confidence interval [95% CI]: 1.21-9.46), electroencephalogram (EEG) grade IV or below based on Young's classification (OR: 3.41, 95% CI: 1.38-8.70), and no bilateral impairments in the basal ganglia (OR: 3.75, 95% CI: 1.50-9.91) or posterior cingulate (OR: 5.61, 95% CI: 2.20-15.54). A nomogram was constructed with the area under the curve of 0.845 (95% CI: 0.780-0.911). Additionally, EEG grade IV or below, and the absence of bilateral impairments in the frontal lobes and occipital lobes were associated with favorable functional outcomes.

INTERPRETATION

These findings underscore the importance of comprehensive early-stage assessments in evaluating consciousness and function, assisting clinicians and families in making clinical decisions.

Research hotspots and trends in the application of electroencephalography for assessment of disorders of consciousness: a bibliometric analysis

Objective

Disorders of consciousness (DoC) result from severe traumatic brain injury and hypoxia or ischemia of brain tissues, leading to impaired perceptual abilities. Electroencephalography (EEG) is a non-invasive and widely applicable technology used for assessing DoC. We aimed to identify the research hotspots in this field through a systematic analysis.

Methods

Relevant studies published from January 1, 2004 to December 31, 2023 were retrieved from the Web of Science Core Collection database. The data were analyzed and visualized using CiteSpace, VOSviewer, and SCImago Graphica.

Results

In total, 1,639 relevant publications were retrieved. The country with the highest number of publications was the United States, the most productive institution was Harvard University, the journal with the highest output was Clinical Neurophysiology, and the journal with the highest total number of citations was Neurology. The author with the most publications was Steven Laureys and the most common keyword was "vegetative state."

Conclusion

The field is undergoing rapid development, characterized by a proliferation of advanced technologies and an increased emphasis on international collaboration. The document offers an impartial perspective on the advancements of the research study for the benefit of the researchers.

Optimizing Neurobehavioral Assessment for Patients with Disorders of Consciousness: Proposal of a Comprehensive Pre-Assessment Checklist for Clinicians

BACKGROUND

Clinicians are challenged by the ambiguity and uncertainty in assessing level of consciousness in individuals with disorder of consciousness (DoC). There are numerous challenges to valid and reliable neurobehavioral assessment and classification of DoC due to multiple environmental and patient-related biases including behavioral fluctuation and confounding or co-occurring medical conditions. Addressing these biases could impact accuracy of assessment and is an important aspect of the DoC assessment process.

METHODS

A pre-assessment checklist was developed by a group of interdisciplinary DoC clinical experts and researchers based on the existing literature, current validated tools, and expert opinions. Once finalized, the checklist was electronically distributed to clinicians with a range of experience in neurobehavioral assessment with DoC. Respondents were asked to use the checklist prior to completing a neurobehavioral assessment. A survey was also provided to respondents to obtain feedback regarding checklist feasibility and utility in optimizing the behavioral assessments.

RESULTS

Thirty-three clinicians completed the survey after using the checklist. Over half of the respondents were a combination of physicians, neuropsychologists, and physical therapists. All respondents served the adult DoC population and 42% percent had over ten years of clinical experience. Eighty percent reported they found the format of the checklist useful and easy to use. All respondents reported the checklist was relevant to preparing for behavioral assessment in the DoC population. Eighty-four percent reported they would recommend the use of the tool to other clinicians.

CONCLUSIONS

The use of a pre-assessment checklist was found to be feasible and efficacious in increasing interdisciplinary clinician's ability to optimize the patient and environment in preparation for neurobehavioral assessment. Initial results of clinicians' perception of the utility of a pre-assessment checklist were positive. However, further validation of the tool is needed with larger sample sizes to improve representation of clinical use across disciplines and care settings.

Parallel EEG-fNIRS assessments of covert cognition in behaviorally non-responsive ICU patients: A multi-task feasibility study in a case of acute motor sensory axonal neuropathy

BACKGROUND

Repeat neurological assessment is standard in cases of severe acute brain injury. However, conventional measures rely on overt behavior. Unfortunately, behavioral responses may be difficult or impossible for some patients. As a result, patients who recover consciousness before the ability to express so may go undetected. Recent studies have demonstrated the efficacy of incorporating functional neuroimaging into clinical assessment protocols. The objective of the current study is to assess the feasibility of a multi-task, multimodal bedside technique to evaluate sensory and cognitive function in behaviorally non-responsive patients.

METHODS

We deployed a novel assessment paradigm to evaluate sensory and cognitive processing in one 63-year-old unresponsive patient with acute motor sensory axonal neuropathy (AMSAN). We collected parallel bedside EEG-fNIRS activity during hierarchical auditory processing, movie listening, and motor imagery.

RESULTS

We found appropriate hemodynamic activation in the patient's middle and superior temporal gyri to simple sounds and activation in their superior temporal gyrus, left angular and precentral gyri during speech. During movie listening, the patient produced patterns of EEG and fNIRS activity that were statistically indistinguishable from healthy controls. The patient also showed appropriate fNIRS and source-localized EEG activation of motor areas during motor imagery. Upon recovering, the patient correctly recalled multiple aspects of our assessment procedures.

CONCLUSION

In sum, our assessment protocol effectively captures neural markers of sensory and cognitive function in behaviorally non-responsive patients. Crucially, while AMSAN is distinct from brain injury, the patient's assumed dissociation between behavior and awareness provided an ideal test case to validate our protocol.

Electrophysiological Signatures of Alpha Coma

PURPOSE

Recent research on quantitative EEG in coma has proposed several metrics correlating with consciousness level. However, the heterogeneous nature of coma can challenge the generalizability of these measures. This study investigates alpha-coma, an electroclinical pattern characterized by a widespread, nonreactive alpha rhythm often linked to poor outcomes. The aim was to quantify the electrophysiological features of alpha-coma and compare them to the alpha rhythm in awake controls, seeking clearer insights into quantitative EEG analysis in comatose states.

METHODS

Fourteen alpha-coma patients were retrospectively selected from University Hospitals of Geneva and age-matched with 14 healthy control subjects from an open-source dataset. EEG data were preprocessed and analyzed to extract power spectra, spectral decay (aperiodic activity), sample entropy, and functional connectivity.

RESULTS

Alpha-coma patients did not differ in alpha power but exhibited significantly higher levels of spectral decay ( p < 0.001), suggesting a convergence toward an inhibitory state. Sample entropy was significantly higher in alpha-coma patients ( p = 0.01), indicating an increase in the cortical complexity in alpha-coma compared with healthy subjects.

CONCLUSIONS

Alpha-coma shows increased aperiodic activity and EEG complexity, despite similar alpha power and clustering coefficient. The increased aperiodic activity aligns with findings in other comatose patients, including those sedated or with subcortical dysfunction. However, the increased entropy contradicts existing literature, suggesting that alpha-coma may represent a state of widespread cortical dysfunction likely resulting from nonhierarchical, turbulent brain activity. This indicates that the loss of consciousness does not guarantee consistent cortical measures across the whole spectrum of EEG patterns.

Global glucose metabolism rate as diagnostic marker for disorder of consciousness of patients: quantitative FDG-PET study

Objective

This study was to employ 18F-flurodeoxyglucose (FDG-PET) to evaluate the resting-state brain glucose metabolism in a sample of 46 patients diagnosed with disorders of consciousness (DoC). The aim was to identify objective quantitative metabolic indicators and predictors that could potentially indicate the level of awareness in these patients.

Methods

A cohort of 46 patients underwent Coma Recovery Scale-Revised (CRS-R) assessments in order to distinguish between the minimally conscious state (MCS) and the unresponsive wakefulness syndrome (UWS). Additionally, resting-state FDG-PET data were acquired from both the patient group and a control group consisting of 10 healthy individuals. The FDG-PET data underwent reorientation, spatial normalization to a stereotaxic space, and smoothing. The normalization procedure utilized a customized template following the methodology outlined by Phillips et al. Mean cortical metabolism of the overall sample was utilized for distinguishing between UWS and MCS, as well as for predicting the outcome at a 1-year follow-up through the application of receiver operating characteristic (ROC) analysis.

Results

We used Global Glucose Metabolism as the Diagnostic Marker. A one-way ANOVA revealed that there was a statistically significant difference in cortical metabolic index between two groups (F(2, 53) = 7.26, p < 0.001). Multiple comparisons found that the mean of cortical metabolic index was significantly different between MCS (M = 4.19, SD = 0.64) and UWS group (M = 2.74, SD = 0.94,p < 0.001). Also, the mean of cortical metabolic index was significantly different between MCS and healthy group (M = 7.88, SD = 0.80,p < 0.001). Using the above diagnostic criterion, the diagnostic accuracy yielded an area under the curve (AUC) of 0.89 across the pooled cohort (95%CI 0.79-0.99). There was an 85% correct classification between MCS and UWS, with 88% sensitivity and 81% specificity for MCS. The best classification rate in the derivation cohort was achieved at a metabolic index of 3.32 (41% of the mean cortical metabolic index in healthy controls).

Conclusion

Our findings demonstrate that conscious awareness requires a minimum of 41% of normal cortical activity, as indicated by metabolic rates.

Guideline: Neurorehabilitation in patients with disorder of consciousness. Recommendations from the Spanish Society of Neurorehabilitation

INTRODUCTION

Clinical practice guidelines in neurorehabilitation for adults with disorders of consciousness by the Spanish Neurorehabilitation Society. This document is based on a review of international clinical practice guidelines published between 2015 and 2022.

METHOD

A total of 7 articles, corresponding to 5 clinical practice guidelines published between 2015 and 2022, were selected by the group of authors from a pool of 48 bibliographic references extracted from various databases in accordance with predefined search criteria. Following this review, forty recommendations were formulated and subjected to evaluation by an expert committee using a 9-point Likert scale: 1-3 (inappropriate recommendation), 4-6 (uncertain recommendation), and 7-9 (appropriate recommendation), following the methodology of the "Modified Nominal Group Technique." Any recommendation endorsed by at least 75% of the experts as "appropriate" (with a score of 7-9) was considered accepted.

CONCLUSIONS

This document presents 40 recommendations categorised according to the level of evidence provided by the reviewed studies. These recommendations represent a consensus among experts and pertain to various aspects related to: 1) clinical assessment, 2) complementary diagnostic tests, 3) prognosis, and 4) treatment in this specific population.

Advances in neuroimaging in disorders of consciousness

Disorders of consciousness (DoC) are a heterogeneous spectrum of clinical conditions, including coma, unresponsive wakefulness syndrome, and minimally conscious state. DoC are clinically defined on the basis of behavioral cues expressed by the patients, on the assumption that such behavioral responses of the patient are representative of the patient's degree of consciousness impairment. However, many studies have highlighted the issues arising from formulating a DoC diagnosis merely on behavioral assessment. Overcoming the limitations of behavioral assessment, neuroimaging provides a direct window on the cerebral activity of the patient, bypassing the motor, perceptual, or cognitive deficits that might hamper the patient's ability to produce an appropriate behavioral response. This chapter provides an overview of available molecular, functional, and structural neuroimaging evidence in patients with DoC. This chapter introduces the neuroimaging tools available in the clinical settings of nuclear medicine and neuroradiology and presents the evidence on the role of neuroimaging tools to improve the clinical management of DoC patients, from the standpoint of differential diagnosis and prognosis. Last, we outline the open questions in the field, and point at actions that are urgently needed to fully exploit neuroimaging tools to advance scientific understanding and clinical management of DoC.

Non-pharmacologic interventions in disorders of consciousness

Severely brain-injured patients with disorders of consciousness pose significant challenges in terms of management, particularly due to the limited therapeutic options available. Despite the potential for some patients to benefit from interventions even years after the injury, clinicians often lack clear and reliable treatment strategies to promote patient recovery. In response to this clinical need, the field of neuromodulation has emerged as a promising alternative to traditional pharmacologic therapies. Both invasive and noninvasive brain stimulation techniques offer diverse possibilities for restoring physiologic neural activity and enhancing functional network integrity in these complex neurological disorders. This chapter offers a comprehensive overview of current neuromodulation techniques, exploring their potential applications and analyzing the existing evidence for their efficacy. Specifically, we describe transcranial electrical stimulation, transcranial magnetic stimulation, deep brain stimulation, low-intensity focused ultrasound, vagal nerve stimulation (including transcutaneous methods), spinal cord stimulation, and median nerve stimulation. While certain approaches show promise for patients with disorders of consciousness, there remains a pressing need for large-scale interventional clinical trials that will play an essential role for elucidating the underlying mechanisms of recovery and for refining stimulation parameters. This, together with the development of tailored individual interventions will move the field forward and optimize therapeutic outcomes.

Best Evidence Summary for the Improvement and Management of Disorders of Consciousness in Patients With Severe Brain Injury

BACKGROUND AND PURPOSE

The treatment effect of consciousness after brain injury is currently uncertain. Thus, this study aimed to retrieve the evidence from neurologists around the world on the management of consciousness disorders in patients with severe brain injury and evaluate and summarize the evidence, providing the guidance on the related management for clinicians.

METHODS

Following the evidence summary report standard of Fudan University Center for Evidence-Based Nursing, clinical guidelines, expert consensuses, systematic reviews, and evidence summaries were systematically retrieved from UpToDate; BMJ Best Practice; Guidelines International Network; the Cochrane Library; Embase; PubMed; Sinomed; Web of Science; CNKI; WanFang database; American Academy of Neurology (AAN); American Congress of Rehabilitation Medicine (ACRM); European Academy of Neurology; and National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR). The publishing timeline for articles was limited from January 2017 to January 2024.

RESULTS

Fourteen articles were finally identified. The 26 best pieces of evidence were recommended by inducting and integrating the evidence from these articles, covering the following seven aspects: consciousness assessment, multidisciplinary team, intervention in facilitating arousal, sensory stimulation programs, drug administration, rehabilitation program, and prevention of complications.

CONCLUSION

This study summarized the evidence of consciousness management in patients with brain injury, providing guidance for clinicians to develop and apply those interventions to improve the patient's clinical outcomes and quality of life. In addition, relevant factors such as the clinical environment and cooperation with the patient's family members should be evaluated and adjusted before applying such evidence. Future studies should focus on more targeted randomized clinical trials.

The social and family evaluation (SAFE) scale for caregivers of individuals with disorders of consciousness: preliminary results

BACKGROUND

Caregivers' involvement in the diagnostic and monitoring processes of the level of consciousness of patients with Disorders of Consciousness (DoC) is strongly encouraged by international guidelines, as current literature suggests a better chance to detect behavioural responses when caregivers are involved in clinical assessments. Since caregivers' involvement during clinical assessments can be difficult, the Social And Family Evaluation (SAFE) scale has been recently proposed as a standardised tool that caregivers can autonomously use to collect their opinions about the level of consciousness of patients with DoC, based on the behaviours manifested by the patients in a given time-window.

OBJECTIVE

Providing preliminary results concerning SAFE adoption.

METHODS

22 patients with DoC were assessed through the Coma Recovery Scale-revised (CRS-r), while their caregivers filled-in the SAFE.

RESULTS

The SAFE showed a very high internal consistency, very high test-retest reliability, and high criterion validity when correlated to the CRS-r total score. Moreover, in line with the literature, the SAFE allowed the detection of some behaviours indicative of a higher level of consciousness than those detected by clinicians through the CRS-r in more than half of the sample.

CONCLUSION

Overall, these preliminary data are promising for the adoption of the SAFE to collect the opinions of the caregivers about the level of consciousness of patients with DoC, especially in those settings where it would be otherwise difficult to monitor the patients, such as long-term care structures and at home, as a tool for telemedicine allowing the monitoring of patients in remote settings.

Parametrization of the dying brain: A case report from ICU bed-side EEG monitoring

BACKGROUND

Cortical high-frequency activation immediately before death has been reported, raising questions about an enhanced conscious state at this critical time. Here, we analyzed an electroencephalogram (EEG) from a comatose patient during the dying process with a standard bedside monitor and spectral parameterization techniques.

METHODS

We report neurophysiologic features of a dying patient without major cortical injury. Sixty minutes of frontal EEG activity was recorded using the Sedline™ monitor. Quantitative metrics of the frequency spectrum, the non-oscillatory 1/f characteristic, and signal complexity with Lemple-Ziv-Welch and permutation entropy were calculated. In addition to comparing the EEG trajectories over time, we provide a comparison to EEG records obtained from other studies with well-known vigilance states (sleep, anesthesia, and wake).

RESULTS

Although we observed changes in high-frequency activation during the dying process, larger alterations of the aperiodic EEG components were also noted. These changes differed dramatically when compared to EEG records representative of wake, slow-wave sleep, or anesthesia. Although still fundamentally unique, the neuronal activity present in the dying brain is more similar to REM sleep than any other state we tested.

CONCLUSION

Even in patients with coma, temporal dynamics in quantitative EEG features (including the aperiodic components) can be observed in the final hour before death.

Emerging ethical issues in patients with disorders of consciousness: A clinical guide

Clinicians who manage patients with disorders of consciousness (DoC) commonly encounter challenging ethical issues. Consciousness disorders include the vegetative state, the minimally conscious state, and covert consciousness resulting from cognitive-motor dissociation. The practice landscape of ethical issues encompasses making the correct diagnosis; making and communicating an accurate prognosis despite irreducible uncertainty; conducting effective shared decision-making with a lawful surrogate decision-maker to deliver goal-concordant care; providing optimal medical, rehabilitative, and palliative care across the spectrum of care sites: acute inpatient, neurorehabilitative, chronic, and palliative; respecting the human rights of and advocating for DoC patient, an historically under-served population and, when appropriate, properly participating in decisions to withhold or withdraw life-sustaining therapy. Research and translational issues in DoC patients include the challenges posed by emerging diagnostics and therapeutics and their prudential integration into clinical practice in the service of patients and their families. Our conceptual analysis of these ethical issues and our practical advice to address them comprise the subject material of this chapter.

Evoked potentials in patients with disorders of consciousness

Acute coma in the intensive care unit and persistent disorders of consciousness (DoC) in neuro-rehabilitation are frequent in patients with hypoxic-ischemic encephalopathy after cardiac arrest (CA), traumatic brain injury, intracranial hemorrhage, or ischemic stroke. Reliable prognostication of long-term neurologic outcomes cannot be made by clinical examination alone in the early phase for many patients, and thus, additional investigations are necessary. Evoked potentials provide inexpensive, real-time, high temporal resolution, bedside, quantifiable information on different sensory pathways into the brain including local and global cortical processing. Short-latency somatosensory evoked potentials can reliably predict poor neurologic long-term outcome in the early phase after CA and are recommended by guidelines as one investigation within an early multimodal assessment. Middle-latency and event-related or cognitive evoked potentials provide information on the integrity of more advanced cortical processing, some closely related to consciousness. This information can help to identify those comatose patients with a good prognosis in the acute phase and help to better understand their precise clinical state and the chances of further recovery in patients with persistent DoC in neuro-rehabilitation. Further studies are necessary to improve the applicability of research findings in the clinical sphere.

A scientific approach to diagnosis of disorders of consciousness

Disorder of consciousness (DoC) are the shared clinical manifestation of severe brain injuries resulting from a variety of etiologies. The nosology of DoC, as well as the armamentarium of methods available to diagnose it, has rapidly evolved. As a result, the diagnosis of DoC is complex and dynamic. We offer an evidence-based approach to DoC diagnosis, highlighting the challenges and pitfalls therein. Accordingly, we summarize the contemporary taxonomy of DoC and its development. We discuss the standardized behavioral diagnostic tools that form the foundation of DoC diagnosis, the evidence for their use, and their limitations. We also highlight recent advances in functional MRI (fMRI) and electroencephalography (EEG) techniques to increase the sensitivity and specificity of DoC diagnosis. We discuss the concept of covert consciousness (i.e., cognitive motor dissociation) as a discrete diagnostic category of DoC, as well as its diagnostic implications. Finally, we underscore issues of neuroethics and equity raised by contemporary models of DoC.

Electrophysiology in disorders of consciousness

Electroencephalography (EEG) has emerged as a powerful tool in the diagnosis, characterization, and prognostication of patients with disorders of consciousness (DoC). EEG is a well-established monitoring tool for the treatment of specific patient populations with impaired consciousness, such as those with status epilepticus and cardiac arrest. The interrogation of neuronal circuitry using evoked and event-related potentials adds prognostic information in comatose individuals. Novel paradigms integrating transcranial magnetic stimulation may provide insights into the underpinnings of arousal and awareness. Covert consciousness, or willful brain activation to motor commands in behaviorally unresponsive patients, may be diagnosed using EEG recordings and has been linked to better outcomes. These advanced EEG methods are increasingly being explored and integrated into the management of DoC patients.

Definitions, diagnostic criteria, and clinical assessment scales in disorders of consciousness

Disorders of consciousness (DoC) are neurologic conditions characterized by severe alteration in level of consciousness. Categories of DoC may include coma, unresponsive wakefulness syndrome/vegetative state, minimally conscious state (MCS; can be further categorized into MCS+ and MCS- based on the presence or absence of language-related behaviors), emergence from MCS, confusional state or delirium, and cognitive motor dissociation (CMD). CMD is a recently defined condition in which the patient fails to demonstrate observable behavioral responses on bedside assessment but demonstrates covert cognitive processing on functional imaging or EEG studies. Accurate differential diagnosis in DoC is aided by adherence to basic principles of assessment, including use of standardized assessment scales. Clinicians should serially administer standardized assessment tools to ensure valid interpretation of results and optimize diagnostic accuracy. Among standardized scales, the Coma Recovery Scale-Revised is most widely used and has the strongest psychometric validity in assessing DoC. The Neurocritical Care Society's Curing Coma Campaign has proposed a slate of DoC common data elements that is expected to improve the consistency and precision of DoC research.

Revolutionizing treatment for disorders of consciousness: a multidisciplinary review of advancements in deep brain stimulation

Among the existing research on the treatment of disorders of consciousness (DOC), deep brain stimulation (DBS) offers a highly promising therapeutic approach. This comprehensive review documents the historical development of DBS and its role in the treatment of DOC, tracing its progression from an experimental therapy to a detailed modulation approach based on the mesocircuit model hypothesis. The mesocircuit model hypothesis suggests that DOC arises from disruptions in a critical network of brain regions, providing a framework for refining DBS targets. We also discuss the multimodal approaches for assessing patients with DOC, encompassing clinical behavioral scales, electrophysiological assessment, and neuroimaging techniques methods. During the evolution of DOC therapy, the segmentation of central nuclei, the recording of single-neurons, and the analysis of local field potentials have emerged as favorable technical factors that enhance the efficacy of DBS treatment. Advances in computational models have also facilitated a deeper exploration of the neural dynamics associated with DOC, linking neuron-level dynamics with macroscopic behavioral changes. Despite showing promising outcomes, challenges remain in patient selection, precise target localization, and the determination of optimal stimulation parameters. Future research should focus on conducting large-scale controlled studies to delve into the pathophysiological mechanisms of DOC. It is imperative to further elucidate the precise modulatory effects of DBS on thalamo-cortical and cortico-cortical functional connectivity networks. Ultimately, by optimizing neuromodulation strategies, we aim to substantially enhance therapeutic outcomes and greatly expedite the process of consciousness recovery in patients.

Navigating uncertainty: a reflexive thematic analysis of rehabilitation staff's perception of communicative interactions in Disorders of Consciousness and Posttraumatic Amnesia

PURPOSE

This study aims to improve our understanding of how communicative interaction is perceived by experienced rehabilitation staff working with patients with Disorders of Consciousness (DoC) and Posttraumatic Amnesia (PTA).

METHOD

This qualitative study involved five workshops guided by modified Nominal Group Technique with 22 professionals from six disciplines. Reflexive thematic analysis was employed for analysis.

RESULTS

Four main themes were developed: (1) Watching carefully for any reaction, (2) The Challenge of careful interpretation, (3) Framing the interaction, and (4) Valued knowledge for involving and communicating with the patient. Rehabilitation professionals exhibited awareness of minimal communicative behaviors but reported regular focus shifts from natural interactions to testing and validating behaviors as part of their clinical reasoning. The emphasis on reliability reflected insecurity in their interpretations. Although spontaneous interactions were recognized, they were often undervalued in favor of reproducible behaviors. Participants also stressed the importance of sharing communicative strategies to ensure consistent patient care.

CONCLUSION

The findings highlight the tension between ethical awareness and clinical reasoning, with staff prioritizing reliability over spontaneous communication. Structured support, training, and interprofessional collaboration are essential to help rehabilitation professionals navigate the complexities of DoC and PTA, ensuring that communicative interactions are effectively supported throughout recovery.

EEG-based responses of patients with disorders of consciousness and healthy controls to familiar and non-familiar emotional videos

OBJECTIVE

To investigate the differences in the brain responses of healthy controls (HC) and patients with disorders of consciousness (DOC) to familiar and non-familiar audiovisual stimuli and their consistency with the clinical progress.

METHODS

EEG responses of 19 HC and 19 patients with DOC were recorded while watching emotionally-valenced familiar and non-familiar videos. Differential entropy of the EEG recordings was used to train machine learning models aimed to distinguish brain responses to stimuli type. The consistency of brain responses with the clinical progress of the patients was also evaluated.

RESULTS

Models trained using data from HC outperformed those for patients. However, the performance of the models for patients was not influenced by their clinical condition. The models were successfully trained for over 75% of participants, regardless of their clinical condition. More than 75% of patients whose CRS-R scores increased post-study displayed distinguishable brain responses to both stimuli.

CONCLUSIONS

Responses to emotionally-valenced stimuli enabled modelling classifiers that were sensitive to the familiarity of the stimuli, regardless of the clinical condition of the participants and were consistent with their clinical progress in most cases.

SIGNIFICANCE

EEG responses are sensitive to familiarity of emotionally-valenced stimuli in HC and patients with DOC.

Altered Mental Status at the Extreme: Behavioral Evaluation of Disorders of Consciousness

Disorders of consciousness represent altered mental status at its most severe, comprising a continuum between coma, the vegetative state/unresponsive wakefulness syndrome, the minimally conscious state, and emergence from the minimally conscious state. Patients often transition between these levels throughout their recovery, and determining a patient's current level can be challenging, particularly in the acute care setting. Although healthcare providers have classically relied on a bedside neurological exam or the Glasgow Coma Scale to aid with assessment of consciousness, studies have identified multiple limitations of doing so. Neurobehavioral assessment measures, such as the Coma Recovery Scale-Revised, have been developed to address these shortcomings. Each behavioral metric has strengths as well as weaknesses when applied in the acute care setting. In this review, we appraise common assessment approaches, outline alternative measures for fine-tuning these assessments in the acute care setting, and highlight strategies for implementing these practices in an interdisciplinary manner.

Resting-State EEG Signature of Early Consciousness Recovery in Comatose Patients with Traumatic Brain Injury

BACKGROUND

Resting-state electroencephalography (rsEEG) is usually obtained to assess seizures in comatose patients with traumatic brain injury (TBI). We aim to investigate rsEEG measures and their prediction of early recovery of consciousness in patients with TBI.

METHODS

This is a retrospective study of comatose patients with TBI who were admitted to a trauma center (October 2013 to January 2022). Demographics, basic clinical data, imaging characteristics, and EEGs were collected. We calculated the following using 10-min rsEEGs: power spectral density, permutation entropy (complexity measure), weighted symbolic mutual information (wSMI, global information sharing measure), Kolmogorov complexity (Kolcom, complexity measure), and heart-evoked potentials (the averaged EEG signal relative to the corresponding QRS complex on electrocardiography). We evaluated the prediction of consciousness recovery before hospital discharge using clinical, imaging, and rsEEG data via a support vector machine.

RESULTS

We studied 113 of 134 (84%) patients with rsEEGs. A total of 73 (65%) patients recovered consciousness before discharge. Patients who recovered consciousness were younger (40 vs. 50 years, p = 0.01). Patients who recovered also had higher Kolcom (U = 1688, p = 0.01), increased beta power (U = 1,652 p = 0.003) with higher variability across channels (U = 1534, p = 0.034) and epochs (U = 1711, p = 0.004), lower delta power (U = 981, p = 0.04), and higher connectivity across time and channels as measured by wSMI in the theta band (U = 1636, p = 0.026; U = 1639, p = 0.024) than those who did not recover. The area under the receiver operating characteristic curve for rsEEG was higher than that for clinical data (using age, motor response, pupil reactivity) and higher than that for the Marshall computed tomography classification (0.69 vs. 0.66 vs. 0.56, respectively; p < 0.001).

CONCLUSIONS

We describe the rsEEG signature in recovery of consciousness prior to discharge in comatose patients with TBI. rsEEG measures performed modestly better than the clinical and imaging data in predicting recovery.

The Antagonism Hypothesis: A New View on the Emergence of Consciousness

PURPOSE

The generation of consciousness poses a complex scientific challenge. Neuroscience and biological sciences have extensively studied this phenomenon, yielding numerous theories and hypotheses. However, to date, no reliable evidence has emerged to exclude any hypothesis conclusively, nor has any theory garnered unanimous agreement. This study aims to offer novel insights for further in-depth study on consciousness.

METHOD

A new theoretical hypothesis was proposed based on reviews and comments from predictive processing theory, information theory, thermodynamics, and neuroscience.

FINDINGS

This study argues that, first, it is necessary to clarify that the core implication of the concept of consciousness is first-person perception. Accordingly, the study of consciousness is based on this premise. Second, on this basis, the antagonistic hypothesis of consciousness generation was proposed. This hypothesis holds that consciousness arises from the antagonism of mature individual experiences that cannot be seamlessly integrated with the function of addressing and navigating these conflicts.

CONCLUSION

The antagonism hypothesis is a new concept regarding the generation of consciousness that deserves further study.

The Recovery of Consciousness via Evidence-Based Medicine and Research (RECOVER) Program: A Paradigm for Advancing Neuroprognostication

Background

Neuroprognostication for disorders of consciousness (DoC) after severe acute brain injury is a major challenge, and the conventional clinical approach struggles to keep pace with a rapidly evolving literature. Lacking specialization, and fragmented between providers, conventional neuroprognostication is variable, frequently incongruent with guidelines, and prone to error, contributing to avoidable mortality and morbidity.

Recent Findings

We review the limitations of the conventional approach to neuroprognostication and DoC care, and propose a paradigm entitled the Recovery of Consciousness Via Evidence-Based Medicine and Research (RECOVER) program to address them. The aim of the RECOVER program is to provide specialized, comprehensive, and longitudinal care that synthesizes interdisciplinary perspectives, provides continuity to patients and families, and improves the future of DoC care through research and education.

Implications for Practice

This model, if broadly adopted, may help establish neuroprognostication as a new subspecialty that improves the care of this vulnerable patient population.

Participatory Development of an International Information Brochure on the Multimodal Assessment of Disorders of Consciousness

BACKGROUND

Disorders of consciousness (DoC) refers to a group of clinical conditions of altered consciousness. To improve their diagnosis and prognosis, multimodal assessment can be of great importance. Informal caregivers of people with DoC who are confronted with new technologies as such can benefit from interventions to expand their health literacy, i.e., the ability to use information to make health decisions for oneself and others.

METHODS

We developed an information brochure on multimodal assessment for DoC in a participatory process, with decisions made by a steering group. The process was based on a methodological framework for the development of patient decision aids that built on the International Patient Decision Aid Standards (IPDAS).

RESULTS

On the background of a broad variety of needs, the priority was to focus on the explanation of multimodal testing and provide information about its uncertainty. Its development aimed at enhancing informal caregivers' understanding of implications of results from multimodal assessment and its relevance for prognosis. It should avoid the portrayal of information that could lead to the impression of false hope or suboptimal rehabilitation care. Informal caregivers rated its usability and acceptability highly, though they preferred less technical language.

CONCLUSION

The participatory process was crucial to the project. Future studies should investigate the effectiveness of the brochure in fostering informal caregivers' health literacy.

PATIENT OR PUBLIC CONTRIBUTION

Informal caregivers of people with DoC were deliberately included in the steering group and they participated in a field test of the prototype brochure.

Arterial Spin Labeling Magnetic Resonance Imaging for Acute Disorders of Consciousness in the Intensive Care Unit

BACKGROUND

To investigate patients with disorders of consciousness (DoC) for residual awareness, guidelines recommend quantifying glucose brain metabolism using positron emission tomography. However, this is not feasible in the intensive care unit (ICU). Cerebral blood flow (CBF) assessed by arterial spin labeling magnetic resonance imaging (ASL-MRI) could serve as a proxy for brain metabolism and reflect consciousness levels in acute DoC. We hypothesized that ASL-MRI would show compromised CBF in coma and unresponsive wakefulness states (UWS) but relatively preserved CBF in minimally conscious states (MCS) or better.

METHODS

We consecutively enrolled ICU patients with acute DoC and categorized them as being clinically unresponsive (i.e., coma or UWS [≤ UWS]) or low responsive (i.e., MCS or better [≥ MCS]). ASL-MRI was then acquired on 1.5 T or 3 T. Healthy controls were investigated with both 1.5 T and 3 T ASL-MRI.

RESULTS

We obtained 84 ASL-MRI scans from 59 participants, comprising 36 scans from 35 patients (11 women [31.4%]; median age 56 years, range 18-82 years; 24 ≤ UWS patients, 12 ≥ MCS patients; 32 nontraumatic brain injuries) and 48 scans from 24 healthy controls (12 women [50%]; median age 50 years, range 21-77 years). In linear mixed-effects models of whole-brain cortical CBF, patients had 16.2 mL/100 g/min lower CBF than healthy controls (p = 0.0041). However, ASL-MRI was unable to discriminate between ≤ UWS and ≥ MCS patients (whole-brain cortical CBF: p = 0.33; best hemisphere cortical CBF: p = 0.41). Numerical differences of regional CBF in the thalamus, amygdala, and brainstem in the two patient groups were statistically nonsignificant.

CONCLUSIONS

CBF measurement in ICU patients using ASL-MRI is feasible but cannot distinguish between the lower and the upper ends of the acute DoC spectrum. We suggest that pilot testing of diagnostic interventions at the extremes of this spectrum is a time-efficient approach in the continued quest to develop DoC neuroimaging markers in the ICU.

Rasch Analysis of the Chinese Version of the Nociception Coma Scale-Revised in Patients with Prolonged Disorders of Consciousness

OBJECTIVES

The aim of this study was to analyze the Chinese version of the Nociception Coma Scale-Revised in patients with prolonged disorders of consciousness within the framework of Rasch modeling, including investigating the invariance of total scores across different etiologies of disorders of consciousness.

DESIGN

Prospective psychometric study.

PARTICIPANTS

Patients with prolonged disorders of consciousness from the Rehabilitation and Neurology units in hospital.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE

The Nociception Coma Scale-Revised was undertaken by trained raters and the Coma Recovery Scale-Revised was used to assess patients' consciousness. The psychometric properties within the Rasch model including item-person targeting, reliability and separation, item fit, unidimensionality, and differential item functioning were assessed.

RESULTS

84 patients with prolonged disorders of consciousness (mean age 53 years; mean injury 5 months; 42 with Minimally Conscious State and 42 with Unresponsive Wakefulness Syndrome) of 252 observations were enrolled in the study. Through the procedure of repeated assessment and differential item function, a lower item bias Rasch set was purified. The Rasch model assumptions were examined and met, with item reliability and validity meeting the recommended threshold.

CONCLUSIONS

The Chinese version of the Nociception Coma Scale-Revised demonstrated unidimensionality, good reliability and separation, and good item fit, but dissatisfied person fit and item-person targeting. The verbal subscale showed a notable discrepancy between person responses and the difficulty of the items, suggesting limited clinical significance.