Traumatic brain injury (TBI) is a major cause of neurological impairment for which there is no effective treatment. Some 1.4 million new cases occur each year in the United States alone, and there is little evidence that those with impaired consciousness will show any improvement after an initial 12-month period. In the most severe cases, TBI can result in a lifetime in an unconscious or partially conscious state. But this grim prognisis may be set to change.

Severe impairment resulting from TBI, including loss of alertness, communication and goal-directed behaviour, has been assumed to result from broad damage to cerebral networks. But recent brain-imaging studies in humans suggest that significant connectivity may persist in some patients in the minimally conscious state (MCS) — a condition characterized by limited or intermittent signs of perception and responses to external stimuli. This convinced Nicholas Schiff, a neurologist at the Weill Cornell Medical College in New York, that patients in the MCS might benefit from deep-brain electrical stimulation (DBS).

Schiff's interest in severe brain injury was piqued by imaging work he did in the early 1990s with patients in the vegetative state. He and Weill medical ethicist Joseph Fins teamed up with MCS expert Joseph Giacino, a neuropsychologist at the JFK Johnson Rehabilitation Institute in Edison, New Jersey, and Ali Rezai, a neurosurgeon at the Cleveland Clinic in Ohio who pioneered therapeutic DBS. The four investigated whether electrical pulses from electrodes implanted in the central thalamus (an important regulator of alertness) could recruit and activate unused but functional cerebral networks in patients in the MCS. They hoped this might improve awareness, communication and other behaviours in such patients.

This began what Schiff describes as “a ten-year process of trying to get the work approved, despite the constant presumption of others that it would never work and wouldn't be worth doing.” The researchers persevered, conducting animal and imaging studies, and developing a surgical approach and an ethical framework for the procedure. This week, they report that DBS can promote significant functional improvements in a patient in the MCS, even 6 years after the initial injury (see page 600).

Their work centred on a single patient who was unable to follow commands consistently, communicate, or vocalize after severe TBI. The team implanted DBS electrodes bilaterally in the central thalamus, then used imaging and behavioural tests to follow and assess the effects of stimulation over an six-month period. The patient's alertness, awareness and motor control improved, and for the first time since his injury he was able to chew and swallow food. Most strikingly, he can now communicate through gestures, words and, at times, short sentences.

Fins stresses that this is not yet a therapy, only a first study that needs confirmation. But, he says, “it is an extraordinary development that, through a prosthetic intervention, this individual regained the ability to participate with the human community.”

Schiff emphasizes that the team's collaboration was essential to their success. He describes the work as “an innovation in neurosurgery”. But, he adds, it's also an innovation in how MCS patient behaviour is assessed and how doctors think about finding ethical ways to improve function in the severely injured brain.