Effect of acoustic stimuli in patients with disorders of consciousness: a quantitative electroencephalography study

Towards an electroencephalographic measure of awareness based on the reactivity of oscillatory macrostates to hearing a subject's own name

We proposed that the brain's electrical activity is composed of a sequence of alternating states with repeating topographic spectral distributions on scalp electroencephalogram (EEG), referred to as oscillatory macrostates. The macrostate showing the largest decrease in the probability of occurrence, measured as a percentage (reactivity), during sensory stimulation was labelled as the default EEG macrostate (DEM). This study aimed to assess the influence of awareness on DEM reactivity (DER). We included 11 middle cerebral artery ischaemic stroke patients with impaired awareness having a median Glasgow Coma Scale (GCS) of 6/15 and a group of 11 matched healthy controls. EEG recordings were carried out during auditory 1 min stimulation epochs repeating either the subject's own name (SON) or the SON in reverse (rSON). The DEM was identified across three SON epochs alternating with three rSON epochs. Compared with the patients, the DEM of controls contained more posterior theta activity reflecting source dipoles that could be mapped in the posterior cingulate cortex. The DER was measured from the 1 min quiet baseline preceding each stimulation epoch. The difference in mean DER between the SON and rSON epochs was measured by the salient EEG reactivity (SER) theoretically ranging from -100% to 100%. The SER was 12.4 ± 2.7% (Mean ± standard error of the mean) in controls and only 1.3 ± 1.9% in the patient group (P < 0.01). The patient SER decreased with the Glasgow Coma Scale. Our data suggest that awareness increases DER to SON as measured by SER.

The Effect of Video Call with Family Members on Physiological Parameters of Critically Ill Patients in Intensive Care Unit: A Quasi-experimental Study

Aim and background

There are not enough studies on the direct effect of virtual patient visits on patients' vital signs in intensive care. The aim of this study is to determine the effect of video calls made between conscious patients and their families on the patient's vital signs and to determine the level of satisfaction.

Materials and methods

The research was carried out quasi-experimentally. Study data were collected from 135 patients and their relatives. The data were collected from the vital signs monitoring form and the Glasgow Coma Scale (GCS). Satisfaction with the video call was measured with a score scale between 0 and 5. Video calls were conducted by an intensive care unit (ICU) nurse every day between 13:00 and 15:00 for 5 days. Physiological parameters were measured 30 minutes before, during, and 30 minutes after the video calls.

Results

The mean patient pulse rate (PR) value was 92.04 ± 12.87, respiratory rate (RR) value was 22.89 ± 3.63, and GCS total score was 14.01 ± 0.12 during the call. There was a statistically significant difference between these values measured during the video calls and the values measured before and after the interview (p < 0.00). The mean score of patient satisfaction with the video call was 4.80 ± 0.44; for relatives, the mean score was 4.87 ± 0.33.

Conclusion

This study revealed that video calls with family members affected PR, RR, and GCS of patients hospitalized in ICU.

Clinical significance

Video calls can be implemented in all ICUs where visits are restricted. This practice is well recognized by both families and patients.

How to cite this article

Uysal N, Vaizoğlu D. The Effect of Video Call with Family Members on Physiological Parameters of Critically Ill Patients in Intensive Care Unit: A Quasi-experimental Study. Indian J Crit Care Med 2023;27(10):732-736.

Evaluation of consciousness rehabilitation via neuroimaging methods

Accurate evaluation of patients with disorders of consciousness (DoC) is crucial for personalized treatment. However, misdiagnosis remains a serious issue. Neuroimaging methods could observe the conscious activity in patients who have no evidence of consciousness in behavior, and provide objective and quantitative indexes to assist doctors in their diagnosis. In the review, we discussed the current research based on the evaluation of consciousness rehabilitation after DoC using EEG, fMRI, PET, and fNIRS, as well as the advantages and limitations of each method. Nowadays single-modal neuroimaging can no longer meet the researchers` demand. Considering both spatial and temporal resolution, recent studies have attempted to focus on the multi-modal method which can enhance the capability of neuroimaging methods in the evaluation of DoC. As neuroimaging devices become wireless, integrated, and portable, multi-modal neuroimaging methods will drive new advancements in brain science research.

Cortical responses to auditory stimulation predict the prognosis of patients with disorders of consciousness

OBJECTIVE

This study aimed to assess the prognosis of patients with disorders of consciousness (DoC) using auditory stimulation with electroencephalogram (EEG) recordings.

METHODS

We enrolled 72 patients with DoC in the study, which involved subjecting patients to auditory stimulation while EEG responses were recorded. Coma Recovery Scale-Revised (CRS-R) scores and Glasgow Outcome Scale (GOS) were determined for each patient and followed up for three months. A frequency spectrum analysis was performed on the EEG recordings. Finally, the power spectral density (PSD) index was used to predict the prognosis of patients with DoC based on a support vector machine (SVM) model.

RESULTS

Power spectral analyses revealed that the cortical response to auditory stimulation showed a decreasing trend with decreasing consciousness levels. Auditory stimulation-induced changes in absolute PSD at the delta and theta bands were positively correlated with the CRS-R and GOS scores. Furthermore, these cortical responses to auditory stimulation had a good ability to discriminate between good and poor prognoses of patients with DoC.

CONCLUSIONS

Auditory stimulation-induced changes in the PSD were highly predictive of DoC outcomes.

SIGNIFICANCE

Our findings showed that cortical responses to auditory stimulation may be an important electrophysiological indicator of prognosis in patients with DoC.

Quantitative analysis of early-stage EEG reactivity predicts awakening and recovery of consciousness in patients with severe brain injury

BACKGROUND

Decisions of withdrawal of life-sustaining therapy for patients with severe brain injury are often based on prognostic evaluations such as analysis of electroencephalography (EEG) reactivity (EEG-R). However, EEG-R usually relies on visual assessment, which requires neurophysiological expertise and is prone to inter-rater variability. We hypothesised that quantitative analysis of EEG-R obtained 3 days after patient admission can identify new markers of subsequent awakening and consciousness recovery.

METHODS

In this prospective observational study of patients with severe brain injury requiring mechanical ventilation, quantitative EEG-R was assessed using standard 11-lead EEG with frequency-based (power spectral density) and functional connectivity-based (phase-lag index) analyses. Associations between awakening in the intensive care unit (ICU) and reactivity to auditory and nociceptive stimulations were assessed with logistic regression. Secondary outcomes included in-ICU mortality and 3-month Coma Recovery Scale-Revised (CRS-R) score.

RESULTS

Of 116 patients, 86 (74%) awoke in the ICU. Among quantitative EEG-R markers, variation in phase-lag index connectivity in the delta frequency band after noise stimulation was associated with awakening (adjusted odds ratio=0.89, 95% confidence interval: 0.81-0.97, P=0.02 corrected for multiple tests), independently of age, baseline severity, and sedation. This new marker was independently associated with improved 3-month CRS-R (adjusted β=-0.16, standard error 0.075, P=0.048), but not with mortality (adjusted odds ratio=1.08, 95% CI: 0.99-1.18, P=0.10).

CONCLUSIONS

An early-stage quantitative EEG-R marker was independently associated with awakening and 3-month level of consciousness in patients with severe brain injury. This promising marker based on functional connectivity will need external validation before potential integration into a multimodal prognostic model.

Behavioral intervention approaches for people with disorders of consciousness: a scoping review

PURPOSE

This review was intended to provide an overall picture of work conducted during the last decade to assess the impact of behavioral intervention strategies on people with disorders of consciousness (i.e., comatose state, vegetative state/unresponsive wakefulness, or minimally conscious state). The intervention strategies considered were those not based on music or including music as a component of the intervention package.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) checklist, a scoping review was carried out to identify and provide a synthesis of eligible studies published in English during the 2010-2021 period. Three databases (i.e., PubMed, PsycINFO, and Web of Science) were employed for the literature search.

RESULTS

Forty studies met the inclusion criteria. Those studies were grouped into three categories based on whether they assessed the effects of: (i) verbal stories/messages, (ii) multiple stimulation, and (iii) response-contingent stimulation. Then, a narrative synthesis of the studies of each of the three categories was provided to specify the types of patients involved, the intervention and assessment conditions implemented, and the outcome attained.

CONCLUSIONS

The evidence reported in most of the studies might be considered encouraging and convincing. Even so, it might be very difficult to view the evidence of the various studies cumulatively and make general/conclusive statements due to a number of differences in the intervention conditions applied.Implications for rehabilitationAn informative picture of the studies using behavioral interventions with people with disorders of consciousness is essential to any professional working in the area.Such picture can be highly useful in providing a view of the intervention strategies used for those people, of the variations existing within and across strategies, and of the evidence available.An analysis of the strategies, their implementation and their effects may provide new insights for improving those strategies and eventually increasing their impact.The individuals charged with the implementation process (e.g., family members or nurses) may have a relevant influence on the overall impact of the strategy.

Auditory event-related potentials based on name stimuli: A pilot study

In recent years, diagnostic studies of brain disorders based on auditory event-related potentials (AERP) have become a hot topic. Research showed that AERP might help to detect patient consciousness, especially using the subjects' own name (SON). In this study, we conducted a preliminary analysis of the brain response to Chinese name stimuli. Twelve subjects participated in this study. SONs were used as target stimuli for each trial. The names used for non-target stimuli were divided into three Chinese character names condition (3CC) and two Chinese characters names condition (2CC). Thus, each subject was required to be in active (silent counting) and passive mode (without counting) with four conditions [(passive, active) × (3CC, 2CC)]. We analyzed the spatio-temporal features for each condition, and we used SVM for target vs. non-target classification. The results showed that the passive mode under 3CC conditions showed a similar brain response to the active mode, and when 3CC was used as a non-target stimulus, the brain response induced by the target stimulus would have a better interaction than 2CC. We believe that the passive mode 3CC may be a good paradigm to replace the active mode which might need more attention from subjects. The results of this study can provide certain guidelines for the selection and optimization of the paradigm of auditory event-related potentials based on name stimulation.

Psychophysiological Effects of Biographical Interventions in People With Unresponsive Wakefulness Syndrome and Minimally Conscious State

Background

Various music interventions can evoke favorable behavioral responses or physiological reactions in people with disorders of consciousness (DOC), such as coma, unresponsive wakefulness syndrome (UWS), and minimally conscious state (MCS). However, it appears that no study thus far has investigated the effects of music on the endocrine system of people with DOC.

Objective

This explorative study aimed to investigate the effects of biographical music and biographical language on the physiological and endocrine systems of people with UWS and MCS.

Method

A cohort of 20 people with DOC (10 women, 10 men; age range 19–77) received 20 min of biographical music and biographical language. Before and afterward, they were exposed to silence. Physiological and hormonal measurements were conducted before, during, and after the interventions.

Results

Paired t-tests showed a significant decrease of salivary cortisol in the condition with biographical language interventions.

Conclusion

Biographical interventions can modulate reactions in the endocrine system in people with DOC. Further studies are needed to establish whether and how individuals living with DOC show psychoneuroendocrine responses to music and other arts-based interventions.

Quantitative EEG may predict weaning failure in ventilated patients on the neurological intensive care unit

Neurocritical patients suffer from a substantial risk of extubation failure. The aim of this prospective study was to analyze if quantitative EEG (qEEG) monitoring is able to predict successful extubation in these patients. We analyzed EEG-monitoring for at least six hours before extubation in patients receiving mechanical ventilation (MV) on our neurological intensive care unit (NICU) between November 2017 and May 2019. Patients were divided in 2 groups: patients with successful extubation (SE) versus patients with complications after MV withdrawal (failed extubation; FE), including reintubation, need for non-invasive ventilation (NIV) or death. Bipolar six channel EEG was applied. Unselected raw EEG signal underwent automated artefact rejection and Short Time Fast Fourier Transformation. The following relative proportions of global EEG spectrum were analyzed: relative beta (RB), alpha (RA), theta (RT), delta (RD) as well as the alpha delta ratio (ADR). Coefficient of variation (CV) was calculated as a measure of fluctuations in the different power bands. Mann-Whitney U test and logistic regression were applied to analyze group differences. 52 patients were included (26 male, mean age 65 ± 17 years, diagnosis: 40% seizures/status epilepticus, 37% ischemia, 13% intracranial hemorrhage, 10% others). Successful extubation was possible in 40 patients (77%), reintubation was necessary in 6 patients (12%), 5 patients (10%) required NIV, one patient died. In contrast to FE patients, SE patients showed more stable EEG power values (lower CV) considering all EEG channels (RB: p < 0.0005; RA: p = 0.045; RT: p = 0.045) with RB as an independent predictor of weaning success in logistic regression (p = 0.004). The proportion of the EEG frequency bands (RB, RA RT, RD) of the entire EEG power spectrum was not significantly different between SE and FE patients. Higher fluctuations in qEEG frequency bands, reflecting greater fluctuation in alertness, during the hours before cessation of MV were associated with a higher rate of complications after extubation in this cohort. The stability of qEEG power values may represent a non-invasive, examiner-independent parameter to facilitate weaning assessment in neurocritical patients.

Music Stimulation for People with Disorders of Consciousness: A Scoping Review

Music stimulation is considered to be a valuable form of intervention for people with severe brain injuries and prolonged disorders of consciousness (i.e., unresponsive wakefulness/vegetative state or minimally conscious state). This review was intended to provide an overall picture of work conducted during the last decade to assess the impact of music on behavioral and non-behavioral responses of people with disorders of consciousness. Following the PRISMA-ScR checklist, a scoping review was carried out to identify and provide a synthesis of eligible studies published in English during the 2010–2021 period. Three databases (i.e., PubMed, PsycINFO, and Web of Science) were employed for the literature search. Thirty-four studies met the inclusion criteria. Those studies were grouped into three categories based on whether they assessed the effects of: (i) recorded music, (ii) interactive music, or (iii) response-contingent music. A narrative synthesis of the studies of each of the three categories was eventually provided. While the studies of all three categories reported fairly positive/encouraging results, several methodological questions make it difficult to draw conclusions about those results and their implications for intervention programs in daily contexts.

Auditory Stimulation Modulates Resting-State Functional Connectivity in Unresponsive Wakefulness Syndrome Patients

Passive listening to music is associated with several psychological and physical benefits in both, healthy and diseased populations. In this fMRI study, we examined whether preferred music has effects on the functional connectivity within resting-state networks related to consciousness. Thirteen patients in unresponsive wakefulness syndrome (UWS) and 18 healthy controls (HC) were enrolled. Both groups were exposed to different auditory stimulation (scanner noise, preferred music, and aversive auditory stimulation). Functional connectivity was analyzed using a seed-based approach. In HC, no differences were found between the three conditions, indicating that their networks are already working at high level. UWS patients showed impaired functional connectivity within all resting-state networks. In addition, functional connectivity of the auditory network was modulated by preferred music and aversive auditory stimulation. Hence, both conditions have the potential to modulate brain activity of UWS patients.

Exploring the neural correlates of self-related names in healthy subjects

OBJECTIVES

This study aimed to clarify the neural correlates and underlying mechanisms of the subject's own name (SON) and the unique name derived from the SON (SDN).

METHODS

A name that was most familiar to the subject (SFN) was added as a self-related reference. We used 4 auditory stimuli-pure tone (1000 Hz), SON, SDN, and SFN-to evaluate the corresponding activated brain areas in 19 healthy subjects by using functional magnetic resonance imaging.

RESULTS

Our results demonstrated that pure tone activated the fewest brain regions. Although SFN was a very strong self-related stimulus, it failed to activate many midline structures. The brain regions activated by SON and SDN were very similar. SFN as a self-related stimulus was less self-related compared with SDN. What's more, the additionally activated fusiform gyrus and parahippocampal gyrus of SDN might revealed its processing path.

CONCLUSIONS

SDN, which has created by us, is a new and self-related stimulus similar to SON. They might provide a useful reference for consciousness assessment with SON and SDN.

Novel sensory paradigms for neuromodulation in disorders of consciousness in traumatic brain injury

PURPOSE OF REVIEW

Traumatic brain injury (TBI) represents a major cause of mortality and disability worldwide. In cases of severe TBI, disorders of consciousness (DoC) can occur and therapeutic options for these conditions are few and of limited efficacy. Sensory stimulation, an instrument to improve arousal and awareness, is frequently applied in the neurorehabilitation of DoC, but scientific evidence supporting its efficacy is limited. Our aim is to review the recent literature concerning novel sensory paradigms used in sensory stimulation protocols in DoC following TBI.

RECENT FINDINGS

Recent studies on sensory stimulation have investigated different types of stimulation protocols, focusing on the issue of how to demonstrate that improvements are related to the treatment applied and not to spontaneous recovery. Moreover, these studies have also shown that paraclinical tests should be useful not only to discover signs of awareness when behavioural assessment fails to do so, but also to measure the effects of sensory stimulation.

SUMMARY

Future studies about novel types of sensory stimulation, whose effects should be possibly measured through paraclinical approaches, are recommended in order to increase the probability that the proper individualized stimulation is administered for each patient.

Clinical Research: Auditory Stimulation in the Disorders of Consciousness

Due to the complex situation of disorder of consciousness (DOC) patients, the assessment of conscious states of these patients has become a huge challenge for a long time (Laureys et al., 2010). At present, the main clinical diagnostic method to assess the conscious state of a DOC patient is the use of a relevant behavior scale like the Coma Recovery Scale-Revised (CRS-R). In this article, we will focus on auditory stimulation and select some representative auditory stimulus, like calling names and music stimulation, to discuss the function and application of the auditory stimulus in patients with DOC and provide guidance for future research.