Objective assessment of visual pursuit in patients with disorders of consciousness: an exploratory study

Collection of the digital data from the neurological examination

This review presents the status quo of how far the digitalization of elements of the neurological examination has progressed. Our focus was on studies that assessed the examination conducted in person, rather than through telemedicine platforms. Five hundred and twenty studies were included in this systematic review. The digital tools covered ten elements of the neurological examination: gait (173, 33%), motor system (149, 29%), eyes (85, 16%), cognitive functions (53, 10%), sensory system (47, 9%), balance (35, 7%), other movements (24, 5%), other cranial nerves (24, 5%), coordination (10, 2%), and autonomic nervous system (9, 2%). Most of the tools were portable (442, 85%), and in 215 studies (41%) the devices were wearable. The cost of the digital tools used was described and discussed in 167 (32%) studies. Most devices (61%) had a low complexity, and half required high additional analytic effort.

Quantitative evaluation of the consciousness level of patients in a vegetative state using virtual reality and an eye-tracking system: A single-case experimental design study

ABSTRACTIt is important to distinguish patients in a minimally conscious state (MCS) from patients in a vegetative state (VS) when assessing disorders of consciousness (DOC) as prognosis, selection of therapy, and drug treatment could differ accordingly. Clinical evaluation of a patient's eye movements, such as visual startle, visual fixation, and visual pursuit, provides valuable evidence but is often subject to misdiagnosis. To minimize such misdiagnosis caused by human judgment, a virtual reality (VR) technology-based quantitative assessment method with an eye-tracking system is proposed in this study. The new VR system presented 3 stimuli to 20 healthy participants, and visual response data were recorded to define valid responses to each stimulus. Further, the newly defined stimuli were presented to five chronic patients in VS, and the system classified three of them as showing visual fixations that could not be verified through clinical assessment beforehand. The proposed system, as verified through such experimentation, suggests quantitative and objective evaluation methods for examining three visual functions of patients with DOC.

Simplified evaluation of CONsciousness disorders (SECONDs) in individuals with severe brain injury: A validation study

BACKGROUND

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.

OBJECTIVE

We aimed to validate a new faster tool to assess consciousness in individuals with DoC.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

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

BACKGROUND AND PURPOSE

Patients with acquired brain injury and acute or prolonged disorders of consciousness (DoC) are challenging. Evidence to support diagnostic decisions on coma and other DoC is limited but accumulating. This guideline provides the state-of-the-art evidence regarding the diagnosis of DoC, summarizing data from bedside examination techniques, functional neuroimaging and electroencephalography (EEG).

METHODS

Sixteen members of the European Academy of Neurology (EAN) Scientific Panel on Coma and Chronic Disorders of Consciousness, representing 10 European countries, reviewed the scientific evidence for the evaluation of coma and other DoC using standard bibliographic measures. Recommendations followed the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. The guideline was endorsed by the EAN.

RESULTS

Besides a comprehensive neurological examination, the following suggestions are made: probe for voluntary eye movements using a mirror; repeat clinical assessments in the subacute and chronic setting, using the Coma Recovery Scale - Revised; use the Full Outline of Unresponsiveness score instead of the Glasgow Coma Scale in the acute setting; obtain clinical standard EEG; search for sleep patterns on EEG, particularly rapid eye movement sleep and slow-wave sleep; and, whenever feasible, consider positron emission tomography, resting state functional magnetic resonance imaging (fMRI), active fMRI or EEG paradigms and quantitative analysis of high-density EEG to complement behavioral assessment in patients without command following at the bedside.

CONCLUSIONS

Standardized clinical evaluation, EEG-based techniques and functional neuroimaging should be integrated for multimodal evaluation of patients with DoC. The state of consciousness should be classified according to the highest level revealed by any of these three approaches.

Conceptualizations of consciousness and continuation of care among family members and health professionals caring for patients in a minimally conscious state

BACKGROUND

The American Academy of Neurology recently emphasized the importance of communicating with patients' families to better reflect patient values in clinical care. However, little is known about how decisions about continuing rehabilitative care made by family caregivers and healthcare providers working with minimally conscious patients are informed by conceptualizations of consciousness and moral status.

METHODS

We explored these issues in interviews with 18 family caregivers and 20 healthcare professionals caring for minimally conscious patients. Data were analyzed using thematic content analysis.

RESULTS

Results suggest that family members and healthcare professionals share similar views of what consciousness is ("being there") and what it is indicated by ("a look in the eyes," and/or an "ability to do"/agency). They also share a belief that the presence (or "level") of consciousness does not determine whether rehabilitative care should be discontinued. Rather, it should be determined by considerations of suffering and well-being. Providers were more likely to view suffering as rationale for discontinuation of care, while family members viewed suffering as an indicator of and motivator for potential recovery.

CONCLUSION

Findings can help optimize family-provider communications about minimally conscious patients by acknowledging shared assumptions and interpretations of consciousness, as well as key areas where perspectives diverge.Implications for rehabilitationFamily and professional caregivers' interpretations of consciousness and suffering are implicated in decisions about continuing rehabilitation for minimally conscious patients.Family members and healthcare providers both rely to some extent on non-observable evidence to evaluate consciousness, which may be an adaptive and philanthropic response to clinical uncertainty.Acknowledging shared assumptions and interpretations of consciousness, as well as diverging perspectives, can help to optimize family-provider communications.

Which behaviours are first to emerge during recovery of consciousness after severe brain injury?

BACKGROUND

Early detection of consciousness after severe brain injury is critical for establishing an accurate prognosis and planning appropriate treatment.

OBJECTIVES

To determine which behavioural signs of consciousness emerge first and to estimate the time course to recovery of consciousness in patients with severe acquired brain injury.

METHODS

Retrospective observational study using the Coma Recovery Scale-Revised and days to recovery of consciousness in 79 patients (51 males; 34 with traumatic brain injury; median [IQR] age 48 [26-61] years; median time since injury 26 [20-36] days) who transitioned from coma or unresponsive wakefulness syndrome (UWS)/vegetative state (VS) to the minimally conscious state (MCS) or emerged from MCS during inpatient rehabilitation.

RESULTS

Visual pursuit was the most common initial sign of MCS (41% of patients; 95% CI [30-52]), followed by reproducible command-following (25% [16-35]) and automatic movements (24% [15-33]). Ten other behaviours emerged first in less than 16% of cases. Median [IQR] time to recovery of consciousness was 44 [33-59] days. Etiology did not significantly affect time to recovered consciousness.

CONCLUSION

Recovery of consciousness after severe brain injury is most often signalled by reemergence of visual pursuit, reproducible command-following and automatic movements. Clinicians should use assessment measures that are sensitive to these behaviours because early detection of consciousness is critical for accurate prognostication and treatment planning.

Public perception of the vegetative state/unresponsive wakefulness syndrome: a crowdsourced study

BACKGROUND

The vegetative state (VS)/unresponsive wakefulness syndrome (UWS) denotes brain-injured, awake patients who are seemingly without awareness. Still, up to 15% of these patients show signs of covert consciousness when examined by functional magnetic resonance imaging (fMRI) or EEG, which is known as cognitive motor dissociation (CMD). Experts often prefer the term unresponsive wakefulness syndrome to avoid the negative connotations associated with vegetative state and to highlight the possibility for CMD. However, the perception of VS/UWS by the public has never been studied systematically.

METHODS

Using an online crowdsourcing platform, we recruited 1,297 lay people from 32 countries. We investigated if vegetative state and unresponsive wakefulness syndrome might have a different influence on attitudes towards VS/UWS and the concept of CMD.

RESULTS

Participants randomized to be inquired about the vegetative state believed that CMD was less plausible (mean estimated frequency in unresponsive patients 38.07% ± SD 25.15) than participants randomized to unresponsive wakefulness syndrome (42.29% ± SD 26.63; Cohen's d 0.164; p = 0.016). Attitudes towards treatment withdrawal were similar. Most participants preferred unresponsive wakefulness syndrome (60.05%), although a sizeable minority favored vegetative state (24.21%; difference 35.84%, 95% CI 29.36 to 41.87; p < 0.0001). Searches on PubMed and Google Trends revealed that unresponsive wakefulness syndrome is increasingly used by academics but not lay people.

DISCUSSION

Simply replacing vegetative state with unresponsive wakefulness syndrome may not be fully appropriate given that one of four prefer the first term. We suggest that physicians take advantage of the controversy around the terminology to explain relatives the concept of CMD and its ethical implications.

Functional MRI Motor Imagery Tasks to Detect Command Following in Traumatic Disorders of Consciousness

Severe traumatic brain injury impairs arousal and awareness, the two components of consciousness. Accurate diagnosis of a patient’s level of consciousness is critical for determining treatment goals, access to rehabilitative services, and prognosis. The bedside behavioral examination, the current clinical standard for diagnosis of disorders of consciousness, is prone to misdiagnosis, a finding that has led to the development of advanced neuroimaging techniques aimed at detection of conscious awareness. Although a variety of paradigms have been used in functional magnetic resonance imaging (fMRI) to reveal covert consciousness, the relative accuracy of these paradigms in the patient population is unknown. Here, we compare the rate of covert consciousness detection by hand squeezing and tennis playing motor imagery paradigms in 10 patients with traumatic disorders of consciousness [six male, six acute, mean ± SD age = 27.9 ± 9.1 years, one coma, four unresponsive wakefulness syndrome, two minimally conscious without language function, and three minimally conscious with language function, per bedside examination with the Coma Recovery Scale-Revised (CRS-R)]. We also tested the same paradigms in 10 healthy subjects (nine male, mean ± SD age = 28.5 ± 9.4 years). In healthy subjects, the hand squeezing paradigm detected covert command following in 7/10 and the tennis playing paradigm in 9/10 subjects. In patients who followed commands on the CRS-R, the hand squeezing paradigm detected covert command following in 2/3 and the tennis playing paradigm in 0/3 subjects. In patients who did not follow commands on the CRS-R, the hand squeezing paradigm detected command following in 1/7 and the tennis playing paradigm in 2/7 subjects. The sensitivity, specificity, and accuracy (ACC) of detecting covert command following in patients who demonstrated this behavior on the CRS-R was 66.7, 85.7, and 80% for the hand squeezing paradigm and 0, 71.4, and 50% for the tennis playing paradigm, respectively. Overall, the tennis paradigm performed better than the hand squeezing paradigm in healthy subjects, but in patients, the hand squeezing paradigm detected command following with greater ACC. These findings indicate that current fMRI motor imagery paradigms frequently fail to detect command following and highlight the need for paradigm optimization to improve the accuracy of covert consciousness detection.

Mirror efficiency in the assessment of visual pursuit in patients in minimally conscious state

OBJECTIVE

Visual pursuit should be tested with a mirror in patients with disorders of consciousness. This stimulus was indeed more efficient than a person or an object, and the auto-referential aspect was supposed to be the key feature. The present study tested the hypothesis that the mirror was more efficient because of its self-aspect.

METHODS

The mirror was compared (1) to the patient's picture and to the picture of a famous face, in 22 patients in minimally conscious state and (2) to the patient's picture and a fake mirror, which had dynamical and bright aspects of the mirror, without reflecting the face, in 26 other patients in minimally conscious state.

RESULTS

The mirror was more efficient than the patient's picture, which was not statistically different from the famous face. The second part of the study confirmed the statistical difference between the mirror and the picture. However, the fake mirror was neither statistically different from the mirror nor from the picture.

CONCLUSIONS

Although our results suggest that the hypothesis proposed by previous studies was partly wrong, they confirm that the mirror is the best stimulus to use when assessing visual pursuit.