Speak kindly – your comatose patient may be listening

At least ‘one quarter of people with brain injuries who seem unresponsive can hear things going on around them and might even be able to use brain-computer interfaces to communicate‘, according to a recent article in Nature.

We have little idea of how many patients there are in the UK with Prolonged (more than six months) Disorders of Consciousness (PDOC) following an acute brain injury. Estimates vary between 5 and 20,000. Of these, some are described as being in a Vegetative State (VS), able to breathe without artificial support but unable to respond to commands and showing no evidence of awareness. They may live for years in this state, given food, water, and nursing care. Others said to be in a Minimally Conscious State (MCS), have at least some awareness of themselves and may be able to perform purposeful movements.

In 2020, the Royal College of Physicians (RCP) published its updated National Guidelines on the management of patients with PDOC. The focus was on developments in assessment since their 2013 guidance, given advances in imaging techniques and electrophysiology. They concluded that, while there may be a place for functional MRI (fMRI) and Positron Emission Tomography (PET) scans and sophisticated electroencephalograms (EEGs) in research, ‘they do not form part of the standard assessment battery’ and that diagnosis ‘rests on clinical observation of behaviours that may suggest awareness of self and the environment’.

Response to the guidance was quick. Scolding et al. took issue with the RCP’s rejection of the routine use of advanced imaging technology. They pointed to ‘a 2016 systematic review and meta-analysis of 37 studies involving more than a thousand patients that showed some 20% to be covertly aware, implying that ‘some tens of thousands of patients worldwide have been erroneously assumed to be “awake but unaware”, sometimes for decades at a time’. They concluded that, ‘given the clinical, ethical and legal importance of determining whether patients with prolonged disorders of consciousness are legally competent or at least able to express their views and feelings,  the Royal College of Physicians requires urgent review’.

Fast-forward to August 2024, an article entitled ‘Cognitive Motor Dissociation in Disorders of Consciousness’ was published in the New England Journal of Medicine NEJM. The authors studied 353 brain-injured patients and found that ‘they may perform cognitive tasks [in response to verbal commands] that are detected fMRI and EEG’ – a phenomenon known as Cognitive Motor Dissociation (CMD).

Two hundred forty-one of the participants had no observable response to spoken commands, and 112 participants did. The presence or absence of an observable response to commands was assessed with the Coma Recovery Scale-Revised (CRS–R).

Using one or both of fMRI and EEG techniques, CMD was discovered in 60 of the 241 (25%) and in 43 of the 112 (38%). That is, approximately one in four participants without an observable response to verbal commands performed a cognitive task on fMRI and/or EEG, and one in three participants with an observable response to commands.

As reported in the journal Nature, 25% of outwardly unresponsive people who showed brain activity tended to be younger than those who did not, to have suffered brain injuries that were from physical trauma, and to have been living with their injuries for longer than the others.

Further research is clearly needed around consciousness-recovery trajectories over time and across different brain injuries, but this is the first large, multi-centred, multi-national investigation of its kind. It supports Scolding’s (above) call for a review of RCP guidance.

Implications of the recent study include:

• some brain-injured patients, previously thought to be unconscious, may be conscious and able to communicate their feelings about what is in their own ‘best interests,’ which in turn will affect decisions made by their family and medical teams caring for them. If it can be shown that they have capacity, the decision-making process around ongoing care will radically change
• potentially, fewer PDOC patients will have clinically assisted nutrition and hydration withdrawn and die by dehydration and sedation
• the process by which ‘brain death’ is assessed ought to change. Medical care today takes a materialistic and utilitarian approach to death. Consciousness (by which is meant higher-order cognitive functioning) and a degree of self-awareness are considered the prime evidence of the presence of life, without which it may be forfeited. The ability to show that some patients considered cortically dead can communicate meaningfully should drive investment and increase access to functional imaging and electrophysiology techniques, currently only available in specialised units.

Surely, the accumulating evidence in support of Cognitive Motor Dissociation, calls for review of the RCP’s guidance lest we inadvertently dehydrate to death those who can hear us make that bedside decision. And speak kindly; there is a higher chance than previously recognised that your comatose patient is listening.