Brain-computer interface enables unresponsive ICU patients to control sounds
· News-MedicalUnresponsive ICU patients in a new Columbia study were able to raise and lower the frequency of a beeping tone with their minds, via noninvasive EEG electrodes that recorded and translated their brainwaves.
The study opens the door to noninvasive brain-computer interfaces that could allow seemingly comatose patients with hidden consciousness to communicate with doctors and family members.
"Our brain-computer interface is only a first step, but it shows that, in principle, we could hopefully in the future give some of these patients a voice."
Hidden consciousness is common
In 2019, his team used standard EEG technology and AI to analyze the brain waves of unresponsive, brain-injured patients and detected signs of hidden consciousness in 15% of the patients. The number shocked the critical care field, which had only documented the phenomenon in a few cases before then.
Though these patients did not respond to commands from their physicians-to blink, make a fist, or wriggle their toes-analysis of the EEG recordings showed that the patients tried to comply but were unable to move their muscles. Claassen's team later found evidence that this dissociation between cognitive and motor functions is caused by a communication breakdown between the brain regions responsible for higher-order cognition and regions that control muscle movement.
In Claassen's studies, patients with cognitive motor dissociation, or CMD, are more likely to regain consciousness and recover a significant amount of day-to-day functioning. Though CMD identification techniques are still not available outside of research studies, they may help physicians in the future identify patients with the best odds of recovery.
Communicating with unresponsive patients
But for an unresponsive, hospitalized patient with severe, acute brain injury, this approach is not ideal.
Instead, Claassen's team attached EEG wires to the heads of patients-a routine part of monitoring brain-injured patients-and trained the patients to control the computer using these EEG waves.
In the study, Claassen's team tested the system with 41 clinically unresponsive patients with acute brain injury a few days after they were hospitalized.
Following a brief training period, about one in three patients were able to control the beeping tones using their thoughts alone, including all patients with CMD that was detected through a separate exam. Surprisingly, these patients were able to control the beeping within a few days of severe brain injury.
Though a previous study has shown that fMRI can be used to obtain answers to simple yes or no questions from a single unresponsive patient, fMRI is not practical for routine use.
Next steps
Study participants and their family members said that having a brain-computer interface for their loved one was helpful and offered advice about ways to improve the technology, including adding personalized features, such as the voice of a loved one, culturally relevant details, and functions to detect pain, hunger, and awareness.
"Our goal is to refine the system so that patients can tell their doctors and loved ones how they are feeling-if they are in pain or hungry, for instance-with more direct communication."
"Patients with hidden consciousness or cognitive motor dissociation are unable to show any expression or communicate in any way," Claassen says. "I think that's where our work can be fundamentally transformative."
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