Bioethics Blogs

Charting the Unpredictable: Using fMRI patterns to determine outcome in acutely comatose patients

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Every year in Canada around 50,000 people suffer brain injuries, with those experiencing severe traumas often becoming comatose for days or weeks post-incident. While there exists a battery of physiological prognostic indicators, such as pupillary light reflex (or lack thereof), and patterns of EEG activity, there remains a significant subset of patients who retain an indeterminate prognosis even after their completion. The use of sophisticated imaging techniques like fMRI has provided a modern way of mapping residual cognitive function in newly comatose patients. Currently, three fMRI studies have looked at the preservation of neural connectivity of two brain networks as potential markers of outcome. While all these studies found a (modest) positive correlation between the BOLD signal strength of the intact network and better patient outcome, significant further work is required before the technique could become clinically useful.

Dr. Charles Weijer of Western University, stresses, however, that this imminent research raises several ethical concerns: patients do not have decisional capacity, time restraints may not permit the proper procurement of surrogate informed consent, critically ill patients are clearly a vulnerable population, and it is not clear how the fMRI study results would impact patient prognosis and treatment decisions. As well, there exist practical concerns including the intra-hospital transport of patients to the fMRI machine, and the time needed outside of the ICU to perform the scans.

As a recent graduate in neuroscience another particular concern struck me – why had the researchers of the previous fMRI studies only considered two networks? The first mapped the preservation of activity in S1 after a stimulus to the hand, while the following two studies assessed the resting state connectivity of the default mode network.

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.