Dr. Neha Dangayach and Drs. Yelena Bodien and Brian Edlow discuss the concept of cognitive motor dissociation (CMD) in neurocritical care, highlighting its implications for patient assessment and treatment.
Show reference:
Neurology Minute
Clinical Implementation of fMRI and EEG to Detect CMD
(upbeat music) - Thank you, Brian and Yelena. I just had an amazing conversation for the Neurology podcast with you. And please, please check out that episode on cognitive motor dissociation. And on this terrific paper that Brian and Yelena have published recently in Neurology Clinical Practice on lessons that they have learned as they try to implement functional MRI and EEG for detecting cognitive motor dissociation for patients with disorders of consciousness. So Yelena, if you could share what is cognitive motor dissociation? - So cognitive motor dissociation describes a phenomenon that we observe in patients who sustained a severe brain injury and subsequently have a disorder of consciousness. So patients who are typically in coma or in a vegetative state or unresponsive weightfulness syndrome, these are patients who are not following commands behaviorally at the bedside. However, when you assess them with task-based functional MRI or with EEG, you put headphones in their ears and you ask them to imagine opening and closing their hand. Despite the fact that they do not open and close their hand at the bedside assessment, they can imagine doing it as we can determine by the fact that they have brain pattern activations that are consistent with being able to imagine a command or an EEG pattern of activation consistent with imagining something. So cognitive motor dissociation refers to patients who physically, motorically are not able to follow commands, but upon assessment of task-based MRI or EEG, we see that their level of cognitive functioning is a lot higher than what we can detect by simply looking at their physical output. - Thank you, Elena and Brian, in your paper, you highlighted several key lessons on implementing functional MRI and EEG for detecting cognitive motor dissociation. What are some key takeaways for our listeners of the neurology minute? - Along with many colleagues in the field who have been doing research for patients with disorders of consciousness back to the since the 2010s and even before with Adrian Owens' paper in 2006, first showing that covert consciousness can be detected in individuals who appear unresponsive at the bedside, we had to learn several lessons as we transitioned from the research application of these tests to their clinical application, which was concurrent with the publication of the US guideline in 2018, endorsing task-based functional MRI and EEG for the detection of covert consciousness, followed by the European guideline in 2020. Once those guidelines were published, we launched an effort for the implementation of these tools being used for clinical purposes, and there were a series of ethical, clinical, regulatory and logistical lessons that we had to learn and navigate over the next several years. The one that I would like to highlight briefly is that of family communication. We had to develop new protocols to ensure that we communicated these results in a carefully worded, compassionate manner. For many of us in the clinical community, these are new tests and we're still trying to find the right words to describe these concepts. So ensuring that we describe cognitive motor dissociation or covert consciousness in a manner that is readily accessible to family members is critically important. And also I would like to highlight the importance of communicating the limitations of these tests. In particular, task-based functional MRI and EEG have high false negative rates. Even in a healthy conscious individuals, the false negative rate is 25%. And therefore, when we talk to families about a negative result, it is essential for us to acknowledge that high false negative rate. It does not mean that their loved one is incapable of generating conscious thought. And a negative test result does not predict poor outcomes. On the other hand, evidence for merging from our colleagues at Columbia in Jan Klossen's group have shown that the presence of covert consciousness in the ICU, like the presence of overt behavioral signs of consciousness, appears to predict long-term recovery of functional independence. And so we need to make sure that we are communicating the implications of a positive result and a negative result with families who's loved ones are currently in the intensive care unit. - Thank you, Brian and Yelena, for sharing your expertise. And do check out the paper published in Neurology Clinical Practice on Functional MRI and EEG. And what are the lessons that you can learn as you try to develop these kinds of programs and how do you think about access to these technologies? But as Brian mentioned on the podcast as well, do not forget the bedside clinical examination and performing a coma recovery scale and a faster version of that developed by Yelena and Kligs is also something that can very much be part of your toolkit in assessing patients with disorders of consciousness. Thank you so much for joining us today. (upbeat music) (upbeat music) [MUSIC] [BLANK_AUDIO]