One in four patients in vegetative or minimally conscious state able to perform cognitive tasks, study finds

cjb250 — Wed, 14 Aug 2024 21:00:11 +0000

Severe brain injury can leave individuals unable to respond to commands physically, but in some cases they are still able to activate areas of the brain that would ordinarily play a role in movement. This phenomenon is known as ‘cognitive motor dissociation’.

To determine what proportion of patients in so-called ‘disorders of consciousness’ experience this phenomenon – and help inform clinical practice – researchers across Europe and North America recruited a total of 353 adults with disorders of consciousness, including the largest cohort of 100 patients studied at Cambridge ̽��ֱ�� Hospitals NHS Foundation Trust.

Participants had mostly sustained brain injury from severe trauma, strokes or interrupted oxygen supply to the brain after heart attacks. Most were living in specialised long-term care facilities and a few were living at home with extensive care packages. ̽��ֱ��median time from injury for the whole group was about eight months.

Researchers assessed patterns of brain activation among these patients using functional magnetic resonance imaging (fMRI) or electroencephalography (EEG). Subjects were asked to repeatedly imagine performing a motor activity (for example, “keep wiggling your toes”, “swinging your arm as if playing tennis”, “walking around your house from room to room”) for periods of 15 to 30 seconds separated by equal periods of rest. To be able to follow such instructions requires not only the understanding of and response to a simple spoken command, but also more complex thought processes including paying attention and remembering the command.

̽��ֱ��results of the study are published today in the New England Journal of Medicine.

Dr Emmanuel Stamatakis from the Department of Clinical Neurosciences at the ̽��ֱ�� of Cambridge said: “When a patient has sustained a severe brain injury, there are very important, and often difficult, decisions to be made by doctors and family members about their care. It’s vitally important that we are able to understand the extent to which their cognitive processes are still functioning by utilising all available technology.”

Among the 241 patients with a prolonged disorder of consciousness, who could not make any visible responses to bedside commands, one in four (25%) was able to perform cognitive tasks, producing the same patterns of brain activity recorded with EEG and/or fMRI that are seen in healthy subjects in response to the same instructions.

In the 112 patients who did demonstrate some motor responses to spoken commands at the bedside, 38% performed these complex cognitive tasks during fMRI or EEG. However, the majority of these patients (62%) did not demonstrate such brain activation. This counter-intuitive finding emphasises that the fMRI and EEG tasks require patients to have complex cognitive abilities such as short-term memory and sustained concentration, which are not required to the same extent for following bedside commands.

These findings are clinically very important for the assessment and management of the estimated 1,000 to 8,000 individuals in the UK in the vegetative state and 20,000 to 50,000 in a minimally conscious state. ̽��ֱ��detection of cognitive motor dissociation has been associated with more rapid recovery and better outcomes one year post injury, although the majority of such patients will remain significantly disabled, albeit with some making remarkable recoveries.

Dr Judith Allanson, Consultant in Neurorehabilitation, said: “A quarter of the patients who have been diagnosed as in a vegetative or minimally conscious state after detailed behavioural assessments by experienced clinicians, have been found to be able to imagine carrying out complex activities when specifically asked to. This sobering fact suggests that some seemingly unconscious patients may be aware and possibly capable of significant participation in rehabilitation and communication with the support of appropriate technology.

“Just knowing that a patient has this ability to respond cognitively is a game changer in terms of the degree of engagement of caregivers and family members, referrals for specialist rehabilitation and best interest discussions about the continuation of life sustaining treatments.”

̽��ֱ��researchers caution that care must be taken to ensure the findings are not misrepresented, pointing out, for example, that a negative fMRI/EEG result does not per se exclude cognitive motor dissociation as even some healthy volunteers do not show these responses.

Professor John Pickard, emeritus professorial Fellow of St Catharine's College, Cambridge, said: “Only positive results – in other words, where patients are able to perform complex cognitive processes – should be used to inform management of patients, which will require meticulous follow up involving specialist rehabilitation services.”

̽��ֱ��team is calling for a network of research platforms to be established in the UK to enable multicentre studies to examine mechanisms of recovery, develop easier methods of assessment than task-based fMRI/EEG, and to design novel interventions to enhance recovery including drugs, brain stimulation and brain-computer interfaces.

̽��ֱ��research reported here was primarily funded by the James S. McDonnell Foundation. ̽��ֱ��work in Cambridge was supported by the National Institute for Health and Care Research UK, MRC, Smith’s Charity, Evelyn Trust, CLAHRC ARC fellowship and the Stephen Erskine Fellowship (Queens’ College).

Reference
Bodien, YG et al. Cognitive Motor Dissociation in Disorders of Consciousness. NEJM; 14 Aug 2024; DOI: 10.1056/NEJMoa2400645

Adapted from a press release from Weill Cornell Medicine

Around one in four patients with severe brain injury who cannot move or speak – because they are in a prolonged coma, vegetative or minimally conscious state – is still able to perform complex mental tasks, a major international study has concluded in confirmation of much smaller previous studies.

When a patient has sustained a severe brain injury, there are very important, and often difficult, decisions to be made by doctors and family members about their care

Emmanuel Stamatakis

Witthaya Prasongsin (Getty Images)

Male patient in a hospital bed - stock image

Acknowledgements

̽��ֱ��multidisciplinary Cambridge Impaired Consciousness Research Group, led by Emeritus Professors John Pickard (Neurosurgery) & David Menon (Anaesthesia) and Drs Judith Allanson & Emmanuel A. Stamatakis (Lead, Cognition and Consciousness Imaging Group), started its research programme in 1997, partly in response to emerging concern over the misdiagnosis of the vegetative state. This pioneering work has only been possible by having access to the world class resources of the Wolfson Brain Imaging Centre, the NIHR/Wellcome Clinical Research Facility at Addenbrooke’s Hospital, the MRC Cognition and Brain Sciences Unit (Professors Barbara Wilson & Adrian Owen), the Royal Hospital for Neuro-disability (Putney) and the Central England Rehabilitation Unit (Royal Leamington Spa).

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Looking into the brain

bjb42 — Tue, 04 Jan 2011 16:15:11 +0000

Neurosurgeon Professor John Pickard is chairman and clinical director of the centre, which uses state-of-the-art positron emission tomography (PET) and magnetic resonance imaging (MRI). “Nobody else in the world has got the kind of facilities that we have,” he says. “These unique facilities have enabled a number of breakthroughs in research. We now have new insights into what happens in the brain as patients emerge from a coma, as well as which parts of the brain are affected by hydrocephalus (‘water on the brain’).”

Doctors are now able to predict the risk of a stroke and distinguish between different types of dementia. Researchers have also used the MRI equipment in new ways to detect how malignant brain tumours spread through the brain and hence focus radiotherapy more appropriately. Other research breakthroughs include the identification of areas of the brain involved in appetite and recognition of facial emotion, leading to new concepts of how brain malfunction may lead to eating disorders and autism. And knowledge gained at the WBIC has helped researchers design new equipment such as the patented scanner that combines PET with MRI, tackling the key problem of how to localise and resolve in fine detail the distribution of novel chemicals within the living brain.

̽��ֱ��Centre’s mission is to advance the understanding and management of the most challenging and critically ill of patients with disorders of the brain, spinal cord and mind from initial illness through rehabilitation to final outcome.

In the last 20 years, death rates for people with acute brain injury have been almost halved because of good medical care. And that does not mean simply keeping people alive – the proportion of severely disabled patients and those in a vegetative state has fallen too. “We are trying to improve the management of patients with acute brain injury and to explore exciting new drugs,” says Pickard. He believes strongly that society still does not understand the need for urgency in managing patients with all forms of ‘brain attack’ and the need for timely rehabilitation. For example, people should act far more quickly on signs of a minor stroke – like short periods when a person is unable to speak – because so much can be done to help. “One of the problems we have to change is the perception of the general public that once you have had a stroke, there is nothing you can do about it. That is not true. If you have a stroke and have treatment, you can avoid ending up in a nursing home for the next 10 or 20 years.” he says.

www.wbic.cam.ac.uk/

̽��ֱ��Wolfson Brain Imaging Centre is a unique venture that brings together scientists and doctors from Cambridge ̽��ֱ�� and Cambridge’s Addenbrookes Hospital for the development of new treatments for patients with brain disorders.

We are trying to improve the management of patients with acute brain injury and to explore exciting new drugs,

John Pickard

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̽��ֱ�� of Cambridge - John Pickard

One in four patients in vegetative or minimally conscious state able to perform cognitive tasks, study finds

Looking into the brain