Current priorities in the understanding and management of disorders of consciousness

Disorders of consciousness present a unique challenge to the clinician. Different pathological states may share a superficially similar presentation but the prognosis and the management required will depend crucially upon the pathologies involved as well as the age and the medical and social history of each patient. Important ethical issues arise whenever life-sustaining procedures are restricted according to assumed prognosis and also whenever the patient cannot communicate, because of the complexity of the relationships between current technical findings on imaging or electroencephalography and the subject’s understanding, awareness, thoughts and feelings.

This means that significant multidisciplinary expertise and variable resources need to be deployed over varied and sometimes unpredictable timescales. In an era in which health service providers increasingly seek predictability when assigning resources, proof of cost-effectiveness of the multidisciplinary expertise and technical resources required for such work is relatively hard to establish. The risk to service provision is thus that funding (always under pressure) is routed instead to fields that are easier to evaluate. This is especially the case where commercial funding (which is intrinsically more at risk from such unpredictability) is a resource on which a patient’s treatment depends. Isolating such expertise in a few special centres enables more technical research to be done and some progress to be made. But it leaves gaps in provision, difficulty in involving families in decision-making and inconsistency in providing them and the patient with continuing support throughout recovery and adaptation.

In concluding their major review of disorders of consciousness published in 2014, Giacino, Fins, Laureys, and Schiff (2014) observed, “Despite the rapidly growing body of evidence indicating that a substantial percentage of patients with DOC recover over time, a belief prevails that these disorders are hopeless and attempts to treat them futile. Consequently, many individuals with DOC” (in the USA)

are transferred directly from high-intensity acute care facilities to custodial settings that are ill-equipped to provide the necessary level of specialized assessment and treatment. A pressing need exists to develop a fully integrated system of care that is responsive to the complex needs of patients with DOC across the different phases of recovery. To this end, new health-care service delivery models must be developed that link academic medical centres, acute care and neurorehabilitation hospitals, and chronic care settings. (p. 12)

This recommendation is no less pressing today, in most countries, and illustrates the continuing need for continual updating of practice. This special issue of Neuropsychological.

Rehabilitation is intended to help by focussing on some recent developments in assessment of disorders of consciousness, imaging, treatment and ethical priorities. The papers in this issue are relevant to our understanding, to clinical practice and to the development of current services for patients with disorders of consciousness, the training and deployment of staff, and the provision of support for patients and families.

Assessment of disorders of consciousness

Assessment has many specific purposes, for example assigning a patient with a disorder of consciousness (DIC) consciousness to a defined subgroup such as Vegetative State (VS), Persisting VS (PVS), Minimally Conscious State (MCS) including its subdivision Akinetic Mutism (AM), and to the Locked-in Syndrome (LIS). Assessments involving direct interaction with an observer may be specifically designed to explore the important elements in such assignment, for example the level of awareness, which can be subdivided into internal self-awareness and external or sensory awareness, which appear to rely upon activation of distinct medial cortico-frontal as opposed to lateral parieto-frontal pathways (Vanhaudenhuyse et al., 2011). The paper in this volume relating to pain thresholds is of particular relevance here.

Of more direct relevance to day to day communication and interaction with the patient, assessments have been designed to explore the capacity to communicate, including a variety of alternatives to language, and the presence of other specific cognitive impairments. Their purpose may be to identify characteristics of the patient likely to be important in communication, motivation and engagement with rehabilitation and support, or to predict prognosis in relation to various possible levels of future functioning. Many of the papers in this issue are designed to explore these areas and to provide feedback to therapists and others involved with the patient that could help them understand the patient’s situation and how to optimise their care and their recovery. Assessment of family strengths and needs, and their relevance to the patient’s future recovery and support, will involve the identification of risk factors for mood disorders and flagging up specific individual needs for their therapy and support. For further comment upon the use and relevance of the assessments reported in this issue, the reader is referred to the papers themselves.

At present, bedside cognitive and functional assessment is still the gold standard in assigning patients to the major subcategories of DOC particularly for individual patients. This has to take account of factors that could mask signs of underlying consciousness, such as sensory (including visual) or motor loss, aphasia (see paper in this volume), epilepsy, intercurrent infection and sedative medication, or even at times a conscious decision by the patient to withdraw from responding. Objective physiological indicators of activity in anatomically defined pathways using scanning, markers of metabolic activity and electrophysiological analysis have greatly helped in the understanding of brain mechanisms and some are on the point of rivalling traditional interactive tests when applied to groups of subjects, for example in predicting eventual functional ability in MCS. Distinct clinical syndromes have been identified, but behavioural features often fluctuate and cross diagnostic borders within individual patients, possibly reflecting aberrant and intermittent dynamic changes in corticothalamic neuronal activity.

Imaging

Structural imaging MRI is the method of choice for visualising the location and extent of brain damage in chronic DOC. In the acute setting, however, CT scanning is easier to achieve and more sensitive to acute haemorrhage and lesions that require immediate surgery. Quantitative diffusion tensor imaging (DTI) techniques permit assessment of both primary and secondary structural white matter damage, for example in the corpus callosum and dorsolateral brainstem, where it implies a poorer prognosis. In DOC, metabolism is particularly impaired in the lateral and medial frontoparietal associative cortices; recovery of consciousness is associated with recovery of activity in this frontoparietal “awareness network” in which frontoparietal midline structures are thought to be important for internal, stimulus-independent or “self” consciousness, whereas lateral frontoparietal cortices are important for external or sensory awareness (Vanhaudenhuyse et al., 2011). Correlating such objective data with clinical evaluation case by case might succeed in progressively deepening our understanding of the mechanisms involved, and eventually in improving not only the specificity of different forms of stimulation and rehabilitation input but also the accuracy of prognosis. However at present, this technology is mainly available in specialised academic units where it is used in research studies, rather than in routine clinical services that serve the general population.

Treatment and rehabilitation

In general, the essence of rehabilitation is to engage and communicate with the patient so as to be in a position to understand the patient’s emotional state, priorities, wishes and needs, and to facilitate behaviour that promotes their awareness, communication, decision-making, sense of wellbeing and autonomy. None of this may be possible in some DOC. Progress is seldom linear or smooth. For example in early phases of recovery of consciousness, automatic elements of behaviour may surface before awareness of saliency in the environment is restored; as time passes and awareness improves, automatic behaviours may thus appear to regress to some extent until the ability to switch attention freely between internal and external stimuli recovers. The factors listed above in relation to cognitive and behavioural bedside assessment will continue to be crucial here.

Physical and emotional discomfort is important to detect and managing both is a day to day priority. The recovery of day to day memory will improve awareness but at the same time increase the risk of rumination and depression. Because patients have individual personalities and expectations, the nature and sequences of the goals espoused by the team will differ from case to case, which complicates attempts to compare the progress that has been made by different groups of patients with different approaches in different rehabilitation settings.

A further complication is that the trajectory of recovery of individuals varies much more than the composite trajectory of a large group. Some individuals make steady progress while others proceed by bursts of improvement alternating with plateaus, that might express no more than an inherent tendency of that individual to lose interest in or tolerance of an exercise programme quite quickly, while being willing to resume it after a break – thus taking longer, but eventually overtaking a more consistent patient and reaching a better level of long term function. The mean prognosis for a group of subjects may provide a useful guideline (Royal College of Physicians, 2013) but cannot be blindly adopted for any individual within the group, since some individuals will do better than expected while others will do worse. This needs to be understood and guidelines adjusted accordingly when commissioning services.

A good rehabilitation service needs to take a long term and individualised view of its patients, and offer flexibility in its timetabling. The value of this is hard to capture in a research study, and hard to get permission for in a commercial organisation whose expectations have been determined by published group trajectories.

Ethical priorities

Such considerations lead directly to ethical issues (Royal College of Physicians, 2013), given the practical and technical difficulty of monitoring the patient’s subjective experiences, wishes and level of suffering, and the expense of continuing care and evaluation. The treating team will also have an ethical duty to provide members of the patient’s family with regular information and to enlist their help in monitoring the patient’s responses, and in sharing their views as to what the patient’s opinions of the situation are likely to have been.

The provider of the hospital or community service treating the patient has also to decide how long to continue to provide expert and intensive care, taking account of the changes in prognosis that inevitably occur as time passes after the injury. At the societal level, is the current pattern of distribution of rehabilitation resources, providing treatment by drugs, therapies and social support ethically sound? Whose responsibility is it to monitor and direct such provision?

Finally, are there any situations in which ensuring a slightly fuller recovery of conscious awareness in a particular individual would be unethical? In most developed countries, the Courts are likely to play a key if ultimate role in safeguarding the rights of the patient to treatment and life support, and in permitting life support to be withdrawn. But Courts can act only if cases are referred to them and there is thus an ethical duty on providers of services in each country to be aware of the laws governing the decisions that providers are allowed to make, and the circumstances in which referral must be made to the Court for advice or for a ruling.

Disclosure statement

No potential conflict of interest was reported by the author.