Using deep brain stimulation, scientists have engineered marked improvements in a patient who could barely eat or speak. T.V. Jayan reports
A hands-on neurosurgeon, Milind Deogaonkar has every reason to feel lucky. After all, this Indian doctor — who headed the neurosurgery department of the National Neurosciences Centre, Calcutta, for three years — was recently witness to history in the making. Currently a staffer at the Cleveland Clinic in the US, Deogaonkar was among a team of physicians and neuroscientists who breathed back life into a patient trapped in a minimally conscious state.
The 39-year-old man (identity withheld) was languishing in a vegetative state when in a revolutionary surgical procedure nearly two years ago the scientists inserted a brain pacemaker. The success, however, came to light only recently when the researchers — drawn from three institutions — reported the work in Nature early this month.
The patient, beaten up during a robbery in 1998, suffered severe brain injury that left him in a minimally conscious state. He could barely keep his eyes open or move his fingers. For six years, he was fed through a tube and did not have any functional limb movement. Before the surgery, he could only mouth words such as “yes†or “no†and even these were hardly audible.
Minimally conscious state refers to a state in which patients show occasional signs of being awake and organised behaviour, and is distinct from a persistent vegetative state or coma. Currently, there are no reliable means for improving recovery from this extended loss of consciousness, which can occur following traumatic brain injury. The glimpses of consciousness such patients exhibit are usually rare, fleeting and unsustainable. Most of those in such a condition are cared for in nursing homes, without the benefits of rehabilitation or status-changing treatment.With the brain pacemaker, however, the scientists have made a beginning, bringing a ray of hope for hundreds of thousands of such patients and their families worldwide.
In this remarkable breakthrough, the scientists made use of an emerging procedure called deep brain stimulation (DBS) — a technique that uses the minutest quantities of electric current supplied through electrodes drilled deep inside the brain with millimetre accuracy. The effect was telling. Over a period of time, it brought marked changes in the patient’s ability to communicate. There was a perceptible improvement in motor movements as well. The man can now communicate through language and gestures, eat through the mouth and drink from a cup, the scientists claim.
No reported medical intervention has so far been able to achieve this. “There have been rare incidents of people in such a state recovering consciousness. But that happened because of the brain’s ability to spring back. And such restoration of consciousness happens normally within a year. It’s almost impossible after a gap of six years,†said Deogaonkar.
But Deogaonkar’s senior colleague at Cleveland, Ali Rezai, and his collaborators from Weill Cornell Medical College, New York, and JFK Johnson Rehabilitation Institute, New Jersey, took up the challenge. “We knew that some patients in the minimally conscious state — including our subject — retain functioning of brain networks above the brainstem,†explained Nicholas Schiff of Weill Cornell, the first author of the Nature paper. Activity within these neural networks is supported by cells in the central thalamus. “The thalamus is the Grand Central Station where signals from sensory organs converge before being despatched to higher cortical regions of the brain for processing,†Deogaonkar, who did his initial medical studies at Mumbai’s KEM Hospital, told KnowHow.
Lateral X-ray image showing DBS implants (top) and Dr Ali Rezai
Courtesy: Cleveland Clinic Foundation
The scientists conjectured that directing electrical impulses to this area would help amplify the existing low level of activity. One way of doing this is deep brain stimulation, which received US Food and Drug Administration approval in 2002. Although expensive, DBS has in the last few years become the last post of treatment for diseases such as Parkinson’s and other neurological disorders relating to depression and anxiety.
Lateral X-ray image showing DBS implants (top) and Dr Ali Rezai
Courtesy: Cleveland Clinic Foundation
DBS surgery targets deep-brain structures using state-of-the-art navigation and brain mapping tools. Tiny electrodes are implanted in these deep-brain structures and connected to programmable pacemaker batteries in the chest. In this particular case, the procedure was performed in two stages that lasted nearly 10 hours, the scientists said.
The researchers, who followed up the patient 480 days after the surgery, said he could now speak a sentence with as many as 16 words at a stretch and chew and swallow his food. “It’s a very compelling change,†said Rezai, a 40-year-old Iranian-American doctor who is regarded as the foremost DBS expert in the US.
Will the DBS-treated patient continue to improve? The scientists say they do not have an answer yet. But the brain’s innate plasticity means the man can build on the gains already achieved.
Although it is difficult to comment on the impact of the technology, the researchers assert that it would definitely be useful in a subset of brain injury patients in the minimally conscious state. “It provides an option where there are none,†said Deogaonkar, who would have had conducted India’s first deep brain stimulation for Parkinson’s disease in Calcutta a few years ago but for the poor financial status of the patient. The medical procedure alone costs nearly Rs 4.5 lakh.
“The clinical improvements (achieved by the scientists) were modest but significant. The report does not suggest that DBS ‘cures’ the condition. However, it emphasises that improvements can be made by patients even long after an injury,†observed Paul Matthews, professor of clinical neurosciences at Imperial College London.
Rezai and his collaborators, too, caution that the extent to which their results might apply to other patients is unknown, and that expectations raised by their findings should be tempered. But they certainly have plans to undertake a larger study involving 12 such patients.
“If this achievement is replicated, its success could usher in a whole new era for the treatment of patients in the minimally conscious state,†said Joseph Fins of Weill Cornell, co-author of the study who specialises in medical ethics.
Needless to say, the patient’s family is very happy with the progress made so far. “I still cry whenever I see him, but these are tears of joy,†said his mother. While he rarely opened his eyes earlier, he now follows her around the room with his eyes and tells her in a clear and audible voice: “I love you, mummy.â€
Source: The Telegraph (Kolkata, India)
