Late recovery from permanent traumatic vegetative state heralded by event-related potentials

Prognostication in Prolonged and Chronic Disorders of Consciousness

Patients with prolonged disorders of consciousness (DOCs) longer than 28 days may continue to make significant gains and achieve functional recovery. Occasionally, this recovery trajectory may extend past 3 (for nontraumatic etiologies) and 12 months (for traumatic etiologies) into the chronic period. Prognosis is influenced by several factors including state of DOC, etiology, and demographics. There are several testing modalities that may aid prognostication under active investigation including electroencephalography, functional and anatomic magnetic resonance imaging, and event-related potentials. At this time, only one treatment (amantadine) has been routinely recommended to improve functional recovery in prolonged DOC. Given that some patients with prolonged or chronic DOC have the potential to recover both consciousness and functional status, it is important for neurologists experienced in prognostication to remain involved in their care.

When, How, and to What Extent Are Individuals with Unresponsive Wakefulness Syndrome Able to Progress? Neurobehavioral Progress

Accurate estimation of the neurobehavioral progress of patients with unresponsive wakefulness syndrome (UWS) is essential to anticipate their most likely clinical course and guide clinical decision making. Although different studies have described this progress and possible predictors of neurobehavioral improvement in these patients, they have methodological limitations that could restrict the validity and generalization of the results. This study investigates the neurobehavioral progress of 100 patients with UWS consecutively admitted to a neurorehabilitation center using systematic weekly assessments based on standardized measures, and the prognostic factors of changes in their neurobehavioral condition. Our results showed that, during the analyzed period, 34% of the patients were able to progress from UWS to minimally conscious state (MCS), 12% of the total sample (near one third from those who progressed to MCS) were able to emerge from MCS, and 10% of the patients died. Transition to MCS was mostly denoted by visual signs, which appeared either alone or in combination with motor signs, and was predicted by etiology and the score on the Coma Recovery Scale-Revised at admission with an accuracy of 75%. Emergence from MCS was denoted in the same proportion by functional communication and object use. Predictive models of emergence from MCS and mortality were not valid and the identified predictors could not be accounted for.

When, How, and to What Extent Are Individuals with Unresponsive Wakefulness Syndrome Able to Progress? Functional Independence

Accurate estimation of the functional independence of patients with unresponsive wakefulness syndrome (UWS) is essential to adjust family and clinical expectations and plan long-term necessary resources. Although different studies have described the clinical course of these patients, they have methodological limitations that could restrict generalization of the results. This study investigates the neurobehavioral progress of 100 patients with UWS consecutively admitted to a neurorehabilitation center using systematic weekly assessments based on standardized measures, and the functional independence staging of those patients who emerged from a minimally conscious state (MCS) during the first year post-emergence. Our results showed that one year after emergence, most patients were severely dependent, although some of them showed extreme or moderate severity. Clinically meaningful functional improvement was less likely to occur in cognitively-demanding activities, such as activities of daily living and executive function. Consequently, the use of specific and staging functional independence measures, with domain-specific evaluations, are recommended to detect the functional changes that might be expected in these patients. The information provided by these instruments, together with that obtained from repeated assessments of the preserved consciousness with standardized instruments, could help clinicians to adjust expectations and plan necessary resources for this population.

Consciousness recovery after various periods in vegetative state

BACKGROUND

Recent studies suggest that late recovery from vegetative state (VS) is more prevalent today than previously thought. This study examined the decline in the rate of recovery from VS with time after admission to rehabilitation, and established a new time frame, in which the odds of recovery from VS remain substantial.

METHODS

Data of 206 patients with VS after traumatic and non-traumatic brain injuries (TBI and NTBI), who were treated at the Loewenstein Rehabilitation Hospital (LRH), in Raanana, Israel, between 2003 and 2015, and described in a previous publication, were further analysed. Rate of recovery from VS was monitored at several time points after admission to intensive care and consciousness rehabilitation (ICCR).

RESULTS

The odds of consciousness recovery were at least 54% at admission to ICCR, and 48%, 33%, 19%, and 7% at 3, 6, 9, and 12 months after admission, respectively.

CONCLUSIONS

The rate of recovery from VS decreases significantly with time, but contrary to previous consensus, 6-12 months after admission to ICCR, the odds of recovery from VS after TBI and NTBI remain substantial.

Longitudinal assessments highlight long-term behavioural recovery in disorders of consciousness

Accurate diagnosis and prognosis of disorders of consciousness is complicated by the variability amongst patients' trajectories. However, the majority of research and scientific knowledge in this field is based on cross-sectional studies. The translational gap in applying this knowledge to inform clinical management can only be bridged by research that systematically examines follow-up. In this study, we present findings from a novel longitudinal study of the long-term recovery trajectory of 39 patients, repeatedly assessed using the Coma Recovery Scale-Revised once every 3 months for 2 years, generating 185 assessments. Despite the expected inter-patient variability, there was a statistically significant improvement in behaviour over time. Further, improvements began approximately 22 months after injury. Individual variation in the trajectory of recovery was influenced by initial diagnosis. Patients with an initial diagnosis of unresponsive wakefulness state, who progressed to the minimally conscious state, did so at a median of 485 days following onset-later than 12-month period after which current guidelines propose permanence. Although current guidelines are based on the expectation that patients with traumatic brain injury show potential for recovery over longer periods than those with non-traumatic injury, we did not observe any differences between trajectories in these two subgroups. However, age was a significant predictor, with younger patients showing more promising recovery. Also, progressive increases in arousal contributed exponentially to improvements in behavioural awareness, especially in minimally conscious patients. These findings highlight the importance of indexing arousal when measuring awareness, and the potential for interventions to regulate arousal to aid long-term behavioural recovery in disorders of consciousness.

Recovery from vegetative state of patients with a severe brain injury: a 4-year real-practice prospective cohort study

Patients who have suffered severe traumatic or nontraumatic brain injuries can show a progressive recovery, transitioning through a range of clinical conditions. They may progress from coma to a vegetative state (VS) and/or a minimally conscious state (MCS). A longer duration of the VS is known to be related to a lower probability of emergence from it; furthermore, the literature seems to lack evidence of late improvements in these patients. This real-practice prospective cohort study was conducted in inpatients in a VS following a severe brain injury, consecutively admitted to a vegetative state unit (VSU). The aim of the study was to assess their recovery in order to identify variables that might increase the probability of a VS patient transitioning to MCS. Rehabilitation treatment included passive joint mobilisation and helping/placing patients into an upright sitting position on a tilt table. All the patients underwent a specific assessment protocol every month to identify any emergence, however late, from the VS. Over a 4-year period, 194 patients suffering sequelae of a severe brain injury, consecutively seen, had an initial Glasgow Coma Scale score ≤ 8. Of these, 63 (32.5%) were in a VS, 84 (43.3%) in a MCS, and 47 (24.2%) in a coma; of the 63 patients admitted in a VS, 49 (57.1% males and 42.9% females, mean age 25.34 ± 19.12 years) were transferred to a specialist VSU and put on a slow-to-recover brain injury programme. Ten of these 49 patients were still in a VS after 36 months; of these 10, 3 recovered consciousness, transitioning to a MCS, 2 died, and 5 remained in a VS during the last 12 months of the observation. Univariate analysis identified male sex, youth, a shorter time from onset of the VS, diffuse brain injury, and the presence of status epilepticus as variables increasing the likelihood of transition to a MCS. Long-term monitoring of patients with chronic disorders of consciousness should be adequately implemented in order to optimise their access to rehabilitation services.

The natural history of continuing improvement in an individual after a long period of impaired consciousness: The story of I.J

AIM

Recovery of consciousness and recovery of function among patients with prolonged disorders of consciousness rarely occur. Those patients who do regain consciousness typically remain with severe disability. The aim of this retrospective study is to suggest that continuing improvement is possible in a survivor of catastrophic brain injury after being in a prolonged state of disordered consciousness.

CASE STUDY

This retrospective single case study follows the progress of a 29 year old man, I.J, who sustained a severe traumatic brain injury following an assault in October 2011. He was in a vegetative state for 15 months and in a minimally conscious state for a further 4 months. This was followed by a slow and steady recovery of motor and cognitive functions. At 3 years post-injury I.J is considered to be moderately disabled. He is now living in the community with continuing outpatient support. On the disability rating scale his level of functioning is rated as mildly dependent.

CONCLUSION

This study shows that continuing recovery to a level of moderate disability is possible, even after a prolonged disorder of consciousness. Intense multi-disciplinary long-term rehabilitation and cranioplasty may be contributing factors for such an unexpected recovery.

Task instructions modulate the attentional mode affecting the auditory MMN and the semantic N400

Event-related potentials (ERPs) have been proven to be a useful tool to complement clinical assessment and to detect residual cognitive functions in patients with disorders of consciousness. These ERPs are often recorded using passive or unspecific instructions. Patient data obtained this way are then compared to data from healthy participants, which are usually recorded using active instructions. The present study investigates the effect of attentive modulations and particularly the effect of active vs. passive instruction on the ERP components mismatch negativity (MMN) and N400. A sample of 18 healthy participants listened to three auditory paradigms: an oddball, a word priming, and a sentence paradigm. Each paradigm was presented three times with different instructions: ignoring auditory stimuli, passive listening, and focused attention on the auditory stimuli. After each task, the participants indicated their subjective effort. The N400 decreased from the focused task to the passive task, and was extinct in the ignore task. The MMN exhibited higher amplitudes in the focused and passive task compared to the ignore task. The data indicate an effect of attention on the supratemporal component of the MMN. Subjective effort was equally high in the passive and focused tasks but reduced in the ignore task. We conclude that passive listening during EEG recording is stressful and attenuates ERPs, which renders the interpretation of the results obtained in such conditions difficult.

Neurophysiological and behavioral responses to music therapy in vegetative and minimally conscious States

Assessment of awareness for those with disorders of consciousness is a challenging undertaking, due to the complex presentation of the population. Debate surrounds whether behavioral assessments provide greatest accuracy in diagnosis compared to neuro-imaging methods, and despite developments in both, misdiagnosis rates remain high. Music therapy may be effective in the assessment and rehabilitation with this population due to effects of musical stimuli on arousal, attention, and emotion, irrespective of verbal or motor deficits. However, an evidence base is lacking as to which procedures are most effective. To address this, a neurophysiological and behavioral study was undertaken comparing electroencephalogram (EEG), heart rate variability, respiration, and behavioral responses of 20 healthy subjects with 21 individuals in vegetative or minimally conscious states (VS or MCS). Subjects were presented with live preferred music and improvised music entrained to respiration (procedures typically used in music therapy), recordings of disliked music, white noise, and silence. ANOVA tests indicated a range of significant responses (p ≤ 0.05) across healthy subjects corresponding to arousal and attention in response to preferred music including concurrent increases in respiration rate with globally enhanced EEG power spectra responses (p = 0.05-0.0001) across frequency bandwidths. Whilst physiological responses were heterogeneous across patient cohorts, significant post hoc EEG amplitude increases for stimuli associated with preferred music were found for frontal midline theta in six VS and four MCS subjects, and frontal alpha in three VS and four MCS subjects (p = 0.05-0.0001). Furthermore, behavioral data showed a significantly increased blink rate for preferred music (p = 0.029) within the VS cohort. Two VS cases are presented with concurrent changes (p ≤ 0.05) across measures indicative of discriminatory responses to both music therapy procedures. A third MCS case study is presented highlighting how more sensitive selective attention may distinguish MCS from VS. The findings suggest that further investigation is warranted to explore the use of music therapy for prognostic indicators, and its potential to support neuroplasticity in rehabilitation programs.

The role of early electroclinical assessment in improving the evaluation of patients with disorders of consciousness

We all share the need to optimise the evaluation of patients with disorders of consciousness (DOC), given the high rate of misdiagnosis of vegetative state based on clinical examination. We believe that one way to do this is to optimise assessment from the early stages, in order to reduce discontinuity between the hospital and rehabilitation phases. While clinical observation remains the "gold standard" for the diagnostic assessment of patients with DOC, neurophysiological investigations (electroencephalography, short latency evoked potentials and event-related potentials) could help to further understanding of the pathophysiology underlying the state of unresponsiveness, differentiate coma from other apparently similar conditions (i.e., locked-in and locked-in-like syndromes), and potentially integrate prognostic evaluation with monitoring of the evolution of the clinical state. Moreover, these techniques have the considerable advantage of being available at the bedside. Discontinuity between the hospital and rehabilitation phases is rightly considered to be one of the critical points in the assessment of patients with DOC. In our view, a continuum of expert neurological assessment that begins with monitoring of the acute phase (focusing on evolution of primary brain damage and secondary complications) and follows through to the patient's discharge from the intensive care unit (focusing on the pathophysiology of brain damage and prognostication based on clinical, neuroimaging and neurophysiological tests) could help to: i) optimise the rehabilitation programme according to the expectations of recovery; ii) provide a basis for comparison with subsequent periodic re-evaluations; iii) ensure uniformity of assessment regardless of the heterogeneity of care facilities; and iv) characterise a subset of patients who, showing discrepancies between neurophysiological tests and clinical status, are more likely to undergo unexpected recovery.

Persistent vegetative and minimally conscious states

The diagnosis and management of patients with persistent vegetative (PVS) and minimally conscious (MCS) states entail powerful medical, ethical and legal debates. The recent description of the MCS highlights the crucial role of unexpected and well-documented recoveries of cognitive functions. Functional neuroimaging has provided new insights for assessing neuropathology and cerebral activity in these patients, providing information on the presence, degree, and location of any residual brain function in patients with PVS or MCS. We present a review on this topic, emphasizing the clinical and neuroimaging assessment of these states, with some of our recent results in this area. We conclude that the development of rehabilitation techniques for patients with PVS and others suffering long-lasting effects of brain injury is a crucial challenge for actual and future generations of neuroscientists.

Late recovery from post-traumatic vegetative state

AIM

Late recovery of consciousness after 12 months in vegetative state is very rare and is almost invariably associated with severe disability. The aim of this study was to report that late recovery with moderate disability is possible, even after several months in vegetative state.

CASE REPORT

This study describes the case of a 22-year-old male student who recovered consciousness from vegetative state 19 months after a traumatic brain injury which had occurred in December 2000. A further slow recovery of motor and cognitive functions up to a moderate disability was observed over 7 years after the brain injury. The patient now lives in the community, speaks, walks and undertakes daily living as well as outdoor leisure activities independently, has resumed his previous university studies and has a part-time non-competitive job.

CONCLUSIONS

This case demonstrates that attaining a condition of independent living is possible even after more than 1 year of post-traumatic vegetative state, with an improvement of motor and cognitive functions that can continue for years. Cranioplasty and long-term rehabilitation programmes may be among the variables potentially influencing this unexpected recovery.

Intrathecal baclofen in patients with persistent vegetative state: 2 hypotheses

Sporadic cases of recovery from persistent vegetative state (PVS) after administration of intrathecal baclofen (ITB) have been reported without giving any possible explanation for its paradoxical effect. We summarize our recent findings on 5 patients with PVS treated with ITB and make some speculations on the mechanisms responsible for the observed clinical improvement. The patients developed spasticity and were judged eligible for ITB therapy. Two weeks after pump implantation, patients began to show a clinical improvement that, at the end of the 6 months' follow-up, was stable in all but 1 patient, ranging from a mere increased alertness to a full recovery of consciousness, as revealed by changes of the Coma Recovery Scale-Revised (CRS-R) score. Our findings suggest that ITB might favor a variable degree of clinical improvement. A proposal for a pharmacodynamic explanation of this effect has not been formally put forward. We hypothesize 2 possible mechanisms: first, a modulation confined to spinal cord segmental activities and to neuronal centripetal outputs reaching the cortex; and second, a modulation of sleep-wake cycles that, although present, may be dysregulated and interfere with alertness and awareness. Although our research is confined to a few subjects, it provides follow-up information by means of the CRS-R that is a validated standardized neurobehavioral instrument expressly designed for use in patients with PVS. Our observations indicate that further systematic investigation of the mechanisms and the putative clinical applications of ITB should be undertaken.