This article is reproduced with the permission of New Scientist for exclusive use by Nova users.

Man roused after six years of minimal consciousness
01 August 2007
NewScientist.com news service

HE WAS assaulted in 1999 and suffered such a severe head injury that the swelling and bleeding forced his brain through the base of his skull. Three months later, the 38-year-old man had emerged from a deep coma into what is known as a minimally conscious state (MCS). Though barely conscious, he woke and slept, showed very occasional signs of awareness and made unreliable attempts to communicate. Now, six years on, doctors have used electrodes implanted into his brain to rouse him to the point where he can speak, eat solid food and control his limbs.

Neurologist Nicholas Schiff of the Weill Cornell Medical College in New York knew from brain scans that large regions of the patient's cerebral hemispheres, including the language regions, were undamaged. But overall his brain was much less active than normal, apparently because areas that trigger wakefulness or arousal by stimulating a region called the thalamus had been damaged and compressed.

Schiff's team also knew from other patients with brain injuries - such as the Massachusetts man Terry Wallis, who came round nearly 20 years after losing consciousness - that such people could harbour "residual function" in undamaged but unconnected regions. They therefore decided to try and artificially stimulate the thalamus by inserting a pair of electrodes directly into it. The technique, known as deep brain stimulation (DBS), has been used as a kind of brain pacemaker for conditions such as Parkinson's disease, chronic pain and tremors, as well as to treat depression and obsessive-compulsive disorder.

After the electrodes had been implanted, Schiff's team allowed the patient to recover for 50 days before turning on the electrodes for 12 hours a day. After a five-month tuning and testing period, the team began a rigorous controlled trial during which the electrodes were only used during alternate months, and the patient's condition was assessed by people unaware of whether they were switched on or not.

When the electrodes were on, the patient's eyes were open for longer, and he was able to make coordinated movements, chew and swallow solid food, follow instructions, and speak intelligibly (Nature, DOI: 10.1038/nature06041). Although the formal trial ended 18 months ago, the man's improvement continues, Schiff says. While his movement is limited after six years of unconsciousness and he has amnesia, he can now eat normally. "The most significant improvement for his carers and family has been the ability to communicate," Schiff adds.

"Clearly this has profound implications for his quality of life," says Adrian Owen of the UK Medical Research Council's Cognition and Brain Sciences Unit in Cambridge. It also suggests that the current practice of discontinuing treatment of MCS patients early and sending them home, will have to be re-evaluated. However, the treatment is complex and may not be suitable for everyone.

"Before this study it was thought that nothing could or should be done for this neglected group of patients," agrees Joseph Fins, an ethics expert at Weill who co-authored the Nature paper. "Now we have a moral obligation to do further research."

Even if DBS does work in other patients, deciding when to intervene could be difficult. There are real concerns about whether all patients would wish to prolong life in a state of partial recovery.

From issue 2615 of New Scientist magazine, 01 August 2007, page 14

For the latest from New Scientiist visit www.newscientist.com