Inside View 33.4 | Page 11

Issue 33.4 FALL 2024 said study corresponding author Dr . Nicholas Schiff , the Jerold B . Katz Professor of Neurology and Neuroscience in the Feil Family Brain and Mind Research Institute at Weill Cornell Medicine , a neurologist at NewYork-Presbyterian / Weill Cornell Medical Center and administrative lead of the consortium . “ I think we now have an ethical obligation to engage with these patients , to try to help them connect to the world .”
The patients in the study were evaluated at New York-Presbyterian / Weill Cornell Medical Center , New York-Presbyterian / Columbia University Irving Medical Center , The Rockefeller University Hospital and Massachusetts General Hospital in the United States , and in medical centers at the University of Cambridge , the University of Liege , and the University of Paris . The Icahn School of Medicine at Mount Sinai served as the coordinating center of the study and conducted the statistical analysis of the patient data .
Cognitive-motor dissociation is thought to be closer to the better-known “ locked-in ” state that isolates an intact brain , typically through either strokes or degeneration of only the motor neurons in amyotrophic lateral sclerosis . But it is seen in patients with more extensive brain injuries who otherwise seem mostly or entirely unaware of their surroundings .
For the study , the researchers enrolled a total of 353 adults with “ disorders of consciousness ,” usually stemming from severe traumatic brain injuries or interrupted oxygen supply to the brain following strokes or heart attacks . Most were under care at home or in longterm care facilities , and the median time from injury was about eight months .
The researchers repeatedly asked each patient to perform a series of continuous motor tasks ( e . g ., “ keep wiggling your toes ”), as well as motor-related cognitive tasks (“ keep imagining wiggling your toes ”) for multiple bouts of 15 to 30 seconds of performance separated by equal length rest periods , using rigorous protocols the investigators had designed and validated to avoid false positives .
Of the 241 patients who were unable to demonstrate bedside command following , 25 % were able to perform the cognitive tasks — matching patterns of EEG- and / or fMRI-measured brain activity seen in healthy subjects in response to the same commands .
While a higher percentage ( 38 %) of the 112 patients who demonstrated motor response to spoken commands at the bedside performed these cognitive tasks , the majority of these patient controls did not demonstrate the cognitive performance . This further dissociation emphasizes that the fMRI and EEG mental imagery tasks demand the sustained use of several cognitive resources , such as short-term memory , that are not required for following bedside commands or even simple communication . The fact that one quarter of the motor-unresponsive patients with cognitive-motor dissociation successfully performed the tasks suggests that many seemingly unconscious patients may be aware and capable of cognition , the researchers said .
“ Some patients with severe brain injury do not appear to be processing their external world . However , when they are assessed with advanced techniques such as task-based fMRI and EEG , we can detect brain activity that suggests otherwise ,” said lead study author Dr . Yelena Bodien , an investigator for the Spaulding-Harvard Traumatic Brain Injury Model Systems and Massachusetts General Hospital ’ s Center for Neurotechnology and Neurorecovery . “ These results bring up critical ethical , clinical and scientific questions – such as , how can we harness that unseen cognitive capacity to establish a system of communication and promote further recovery ?”
In the United States alone , the number of people estimated to be in a chronic vegetative state ranges from 5,000 – 42,000 , while estimates for those in a minimally conscious state range from 112,000 to 280,000 individuals .
The findings are likely to lead to several new lines of research . One is to investigate easier methods of detecting this dissociation — methods that , unlike task-based fMRI and EEG , could be used in a greater variety of clinics .
Another is to explore the potential clinical value of detecting cognitive-motor dissociation , since prior studies suggest that patients with this condition may have a greater chance of recovery compared with those who cannot perform cognitive tasks .
“ Just knowing that a patient has this ability to respond cognitively can be a game-changer in terms of life-support decisions and the degree of engagement of caregivers and family members ,” Dr . Schiff said .
He added that the findings should also lead to studies of specific interventions — likely including brain-computer interfaces — to improve the quality of life for these patients and further boost their chances of recovery .
“ What we need here is what we in our consortium have been trying to get started for 20 years : a sustained effort to benefit patients who have disorders of consciousness with systematic medical research , technology development and better clinical infrastructure ,” Dr . Schiff said .
Dr . Barry Coller , physician-in-chief of The Rockefeller University Hospital , led the effort to develop a model clinical infrastructure to support the research and credits Dr . Schiff and Dr . Joseph J . Fins , the E . William Davis , Jr ., MD Professor of Medical Ethics at Weill Cornell Medicine and chief of the Division of Medical Ethics at Weill Cornell Medicine and NewYork-Presbyterian / Weill Cornell Medical Center , with conceiving the study . “ I realized the importance of bringing hope to these patients and their loved ones ,” Dr . Coller said . “ We are proud to be a part of this pioneering research , which has creatively harnessed all of the power of modern science , and we are very gratified by the results .” g
10