Brain zap rouses people from years of vegetative state

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Treatment might be possible (Image: Michele Constantini/plainpicture)

People in a vegetative state showed signs of awareness after electric brain stimulation and minimally conscious people were able to communicate again

TALK about an awakening. People who have been in a minimally conscious state for weeks or years have been temporarily roused using mild electrical stimulation.

Soon after it was applied to their brains, 15 people with severe brain damage showed signs of consciousness, including moving their hands or following instructions using their eyes. Two people were even able to answer questions for 2 hours before drifting back into their previous uncommunicative state.

"I don't want to give people false hope these people weren't getting up and walking around but it shows there is potential for the brain to recover functionality, even several years after damage," says Steven Laureys at the University of Lige in Belgium, who led the research.

People with severe brain trauma often fall into a coma. If they "awaken", by showing signs of arousal but not awareness, they are said to be in a vegetative state. This can improve to a state of minimal consciousness, where they might show fluctuating signs of awareness, which come and go, but have no ability to communicate.

External stimulation of the brain has been shown to increase arousal, awareness and aspects of cognition in healthy people. So Laureys and his colleagues wondered if it would do the same in people with severe brain damage. They used transcranial direct current stimulation (tDCS), which doesn't directly excite the brain, but uses low-level electrical stimulation to make neurons more or less likely to fire.

The team worked with 55 people who had experienced a traumatic brain injury or lack of oxygen to the brain and were in a minimally conscious or vegetative state. They placed electrodes over their left dorsolateral prefrontal cortex an area involved in memory, decision-making and awareness. Then they delivered 20 minutes of stimulation to some of the people and a sham treatment to the others. The next day, the two groups received the opposite therapy.

During brain stimulation, 13 people with minimal consciousness and two people in a vegetative state showed signs of awareness that were observed neither before the stimulation nor after the sham treatment.

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Brain zap rouses people from years of vegetative state