Assisted by tiny electrodes implanted in his brain, a man who had been in a coma-like state for six years regained the ability to drink from a cup, comb his hair and speak in short sentences, researchers said Wednesday.
Within hours of receiving what researchers described as a pacemaker for the brain, the man opened his eyes and tracked the movement of people in his hospital room.
More than a year later, the man's progress has continued, and recently he recited the first 16 words of the Pledge of Allegiance, researchers said.
The report, published in the journal Nature, challenges the belief that patients in minimally conscious states for prolonged periods are untreatable, researchers said.
"This is a real landmark," said neuroscientist Adrian Owen of the Medical Research Council's Cognition and Brain Sciences Unit in Cambridge, England, who was not involved in the research. "This suggests a possible treatment for some patients."
Researchers said the technology would not benefit every minimally conscious patient. The cause and severity of brain injuries vary widely, they said, and specific brain connections must remain intact for the treatment to work.
Still, "the report provides hope," said Dr. Paul Matthews, a professor of clinical neuroscience at Britain's Imperial College London who was not connected to the study. "It emphasizes that improvements can be made by patients even long after an injury."
In a minimally conscious state, a patient shows intermittent signs of awareness but is generally unable to communicate with the outside world. It is less severe than persistent vegetative state, in which a patient is awake but lacks awareness of self or surroundings.
The late Terri Schiavo had been in a persistent vegetative state for 15 years when her husband won a bitter court battle to have her feeding tube removed in 2005.
There are 100,000 to 300,000 minimally conscious patients in the U.S., researchers said, and most of them are cared for in long-term nursing homes.
The man in the study suffered severe brain injury after he was robbed, beaten and left for dead. Researchers did not identify him but said he is 38 and lives in an East Coast facility.
Before treatment, the man occasionally nodded his head and mouthed "yes" or "no" but seldom opened his eyes. Unable to swallow, he received nourishment through a feeding tube.
Using computer-generated maps and image-guided navigation equipment, researchers implanted tiny electrodes in the man's thalamus, a brain area involved in attention, movement and other control functions. The electrodes were attached by wires to programmable pacemaker batteries implanted in the man's chest.
The device, called a deep brain stimulator, delivers electrical pulses to the brain and is approved to treat such neurological disorders as Parkinson's disease.
No one is certain exactly why the device worked.
Study author Joseph T. Giacino of the JFK Johnson Rehabilitation Institute in Edison, N.J., said researchers believed that electrical impulses from the device amplified the low level of activity in the man's brain. The device improved the efficiency of signals that drive speech and function to get them working better, he said.
Giacino said it was possible that the man would continue to improve, although use of his limbs would remain severely limited because of muscle contractures resulting from his long period of immobility. For example, Giacino said, the man can bring a toothbrush to his mouth but lacks the coordination to use it.
The man's mother, who also remained anonymous, said that before his treatment, she had signed a "do not resuscitate" order for her son.
"Now he can cry and laugh and say 'Mommy' and 'Pop,' " she said during a news briefing. "I cry every time I see my son, but now it's tears of joy."
The study, which also involved researchers from Weill Cornell Medical College in New York City and the Cleveland Clinic in Ohio, was funded by the National Institute of Neurological Disorders and Stroke, the National Institute on Disability and Rehabilitation Research and other sources.
The study is continuing, and researchers said they hoped to eventually test the device in 12 minimally conscious patients.