ATLANTA, GEORGIA--An operation using electrodes to stimulate the brain has brought about a dramatic improvement in the condition of a man in a minimally conscious state, researchers reported here Sunday at the annual meeting of the Society for Neuroscience. While a just a single case study, the patient's remarkable recovery raises the hope that physicians may have uncovered a new way to treat serious brain injuries.
The patient suffered significant brain damage in an assault that happened in his early thirties. "This is about as severe a brain injury as you could survive," says research team member Nicholas Schiff, a neurologist at Weill Medical College of Cornell University in New York City. In 2004, six years after the beating, the man remained in what neurologists call a minimally conscious state. People in this condition have limited and sporadic awareness of their surroundings and are generally unable to communicate or respond to spoken instructions.
A magnetic resonance imaging (MRI) scan of the patient revealed substantial damage to the right frontal lobe of his brain, which mediates many higher cognitive functions, including abstract thought. Other kinds of scans that looked more directly at brain function, however, suggested that important neural circuits remained intact, if underactive. A functional MRI scan, for example, detected a promising pattern of neural responses to spoken language, says Schiff.
In 2004, hoping to boost the overall level of activity in the man's brain, the team, which was led by neurosurgeon Ali Rezai of the Cleveland Clinic in Ohio, implanted two electrodes into the man's central thalamus. The region is a crucial relay station between brain stem areas that mediate arousal and the cerebral cortex. When doctors turned the electrodes on, the man became noticeably more alert almost immediately, Schiff says. And over the course of 2 months, the injured man's scores improved on clinical measures of arousal, movement, and communication. Now, two years later, he can give an intelligible, accurate response about half the time when asked to name objects in photographs. Moreover, the man maintains this improved level of consciousness even when the electrodes are temporarily switched off for testing, suggesting that the stimulation has had a long-term strengthening effect on some neural circuits.
Deep brain stimulation has been used previously to treat Parkinson's disease, and some recent studies suggest it could help people with depression and other psychiatric disorders. But it has had only limited success in patients with consciousness disorders, says David Hovda, a neuroscientist who does clinical studies with brain injury patients at the University of California, Los Angeles. One likely reason is that not all brain injury patients have enough neural circuitry intact to benefit from this surgery. But using sophisticated imaging to identify those who do should improve the odds of success, Hovda says.
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