Bedside EEG test aids prognosis in patients with brain injury

A prognostic tool

The simple approach promises to be more accessible than fMRI, said Dr. Sokoliuk. “Putting an unresponsive coma patient in a scanner is very difficult and also much more expensive,” she said.

The next step, said Dr. Sokoliuk, is to repeat the study with a larger sample. “The number in the current study was quite small, and we can’t say if the sensitivity of the paradigm is strong enough to use it as a standard prognostic tool.”

To use it in clinical setting, “we really have to have robust measures,” she added.

She aims to conduct a collaborative study involving several institutions and more patients.

The research team plans to eventually build “an open-access toolbox” that would include the auditory streams to be played during EEG recordings and a program to analyze the data, said Dr. Sokoliuk. “Then, in the end, you would get a threshold or a value of tracking for phrases and sentences, and this could then classify a patient to be in a good-outcome or in bad-outcome group.”

She stressed this is a prognostic tool, not a diagnostic tool, and it should not be used in isolation. “It’s important to know that no clinician should only use this paradigm to prognosticate a patient; our paradigm should be part of a bigger battery of tests.”

But it could go a long way toward helping families as well as physicians. “If they know that the patient would be better in 3 months’ time, it’s easier for them to decide what should come next,” she said.

And it’s heartening to know that when families talk to their unresponsive loved one, the patient understands them, she added.
 

Promising basic research

Commenting on the study in an interview, Christine Blume, PhD, of the Center for Chronobiology, University of Basel (Switzerland), whose research interests include cognitive processing of patients with disorders of consciousness, described it as “very elegant and appealing” and the paradigm it used as “really promising.”

“However, we do, of course, not yet know about the prognostic value on a single-subject level, as the authors performed only group analyses,” said Dr. Blume. “This will require more extensive and perhaps even multicenter studies.”

It would also require developing a “solution” that “allows clinicians with limited time resources and perhaps lacking expert knowledge on the paradigm and the necessary analyses to apply the paradigm at bedside,” said Dr. Blume.

She agreed that a passive paradigm that helps determine whether a patient consciously understands speech, without the need for further processing, “has the potential to really improve the diagnostic process and uncover covert consciousness.”

One should bear in mind, though, that the paradigm “makes one essential assumption: that patients can understand speech,” said Dr. Blume. “For example, an aphasic patient might not understand but still be conscious.”

In this context, she added, “it’s essential to note that while the presence of a response suggests consciousness, the absence of a response does not suggest the absence of consciousness.”

Dr. Blume cautioned that the approach used in the study “is still at the stage of basic research.” Although the paradigm is promising, “I do not think it is ‘around the corner,’ ” she said.

The study was funded by the Medical Research Council. It was further supported by the National Institute for Health Research Surgical Reconstruction and Microbiology Research Center. Dr. Sokoliuk and Dr. Blume have disclosed no relevant financial relationships.

A version of this article first appeared on Medscape.com.