What an awakening. A man has been roused from a minimally conscious state by stimulating his brain with ultrasound.
The 25-year-old man, who had suffered a severe brain injury after a road traffic accident, progressed from having only a fleeting awareness of the outside world to being able to answer questions and attempt to walk.
He was the first person in the world to undergo an experimental procedure that stimulates the thalamus deep inside the brain, using pulses of ultrasound. 鈥淚t鈥檚 only in one person but it鈥檚 extremely exciting,鈥� says at the University of California, Los Angeles.
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Monti and his team have been searching for a way to help people with brain injuries that result in disorders of consciousness, for whom there are few treatments. One kind of disorder is a minimally conscious state, in which a person shows fluctuating signs of awareness, but cannot communicate.
Animal experiments suggested that stimulating the thalamus might help promote arousal. Rats under anaesthesia after thalamic stimulation, for example. But the thalamus is deep inside the brain, making it difficult to try on people.
It is possible to use deep brain stimulation. In 2007, a 38-year-old man who had been in a minimally conscious state for six years showed after receiving deep brain stimulation to his thalamus, but this involved implanting electrodes into his brain, a procedure that risks damaging other areas.
Monti鈥檚 team decided to try using low intensity ultrasound instead, which can safely modulate deep brain tissues without harming the surrounding areas.
Trying to communicate
They tried this technique on a patient who had been in a minimally conscious state for almost three weeks. Monti placed an ultrasound transducer on the patient鈥檚 temple, and used brain scans to check he had positioned it correctly. 鈥淸the temple] is the perfect window to the thalamus, which lies seven centimetres below,鈥� says Monti.
They then stimulated the man鈥檚 thalamus for 10 minutes, alternating between 30 seconds of ultrasound and 30 seconds rest.
Immediately afterwards, the man scored worse on tests of consciousness. 鈥淭his wasn鈥檛 surprising,鈥� says Monti. 鈥淭aking part in procedures like this fatigues the injured brain very quickly.鈥�
But the following morning was a different story. The patient was starting to vocalise and gesture in response to questions, behaviours he had not shown before treatment. 鈥淗e seemed to clearly understand language and was trying to communicate,鈥� says Monti.
Fist-bumping
Over the next three days the man started answering questions by nodding or shaking his head. 鈥淚 made a fist with my hand and said 鈥榗an you fist bump me?'鈥� says Monti. 鈥淗e was young, I thought he鈥檇 like that 鈥� and he immediately put out his fist out and bumped me, no pause or anything.鈥� A week later, the patient tried to walk.
But we can鈥檛 know yet whether his recovery might have been a coincidence. 鈥淚鈥檇 love to start yelling success, this is exactly what we hoped we would see,鈥� says Monti. 鈥淏ut we can鈥檛 get too excited before testing it on others. The patient could have spontaneously recovered in that period of time. It would have been serendipitous, but possible. But it鈥檚 extremely exciting and encouraging.鈥�
, associate professor of neurology at George Washington University, Washington DC, agrees that Monti鈥檚 report of the procedure is both interesting and promising. However, he also says that young individuals can recover spontaneously. 鈥淎 controlled trial in patients with various [disorders of consciousness] is warranted before making any definitive conclusions,鈥� he says.
Thalamic intervention
The thalamus is a kind of hub situated in the centre of the brain, which acts as a relay between many other regions. It is thought to be vital to sleep and wakefulness.
Monti says it鈥檚 not yet clear whether the thalamus underlies the fundamental aspects of conscious awareness, or if it is instead involved in helping patients produce behaviours that give a sign that they are aware of the world around them.
鈥淚t鈥檚 difficult to tease these two things apart,鈥� he says.
鈥淏y stimulating the thalamus, did we allow him to start integrating different areas of the brain and buzz him back into consciousness, or was he conscious before and we just gave him the ability to plan movements that showed us he was aware?鈥�
Monti asked the patient whether he was aware of having the procedure and he said no. 鈥淭his doesn鈥檛 tell us much though, because he could have been aware of the procedure and then experienced memory loss,鈥� says Monti.
His team is now hoping to test the procedure on 10 to 15 more people with disorders of consciousness. They also want to trial it on healthy people, to help understand the effects of stimulating the thalamus. 鈥淚鈥檇 love to know what happens if we inhibit the healthy person鈥檚 thalamus 鈥� would it prevent them from moving and answering questions or would it make them unconscious?鈥�
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