July 31, 2007

deep brain stimulation in a minimally conscious state, as published in Nature

Scientists commented on a report that the stimulation of the brain of a 38-year-old man using implanted electrodes had considerably improved his ability to communicate.

Paul Matthews, Professor of Clinical Neurosciences, Imperial College, London, said:

“Scientists have known that structures deep in the brain control consciousness and that injury to them can cause a minimally conscious state or coma. Deep brain stimulation is a now routinely performed type of neurosurgical procedure that can modulate functions in these deep brain structures. Although based on a study of only a single patient, this report suggests that deep brain stimulation may be adapted to benefit at least some patients with minimally conscious states. The report provides hope that there is an alternative to supportive care and conventional neurorehabilitation alone.

“The causes and severity of brain injury vary between minimally conscious state patients. Although we do not know precisely which brain connections are important, we may expect that some specific connections must be intact for deep brain stimulation to have a beneficial effect. The current study is based on a single case. More experience with the approach is needed to understand which patients may be expected to benefit.

“The clinical improvements were modest but significant. The report does not suggest that deep brain stimulation ‘cures’ minimally conscious state. However, it emphasises that improvements can be made by patients even long after an injury.”

Prof Tipu Aziz, Professor Of Neurosurgery, University Of Oxford, said:

“The minimally conscious or persistent vegetative state is as yet to be accurately defined but simply stated is a state in which a person loses higher cerebral functions but maintains a sleep wake cycle. There are some studies that are suggestive of the fact that deep brain stimulation of the centrum medianum parafascicularis complex to activate the cortex can raise patients from this state (1). However, there are also cases of patients recovering spontaneously a long time after injury from such a state (2) and therefore one cannot draw any firm conclusions. This would appear to be another such report and again extrapolation to the general management of such patients is not possible.

“The ethics of intervention in such patients is still very difficult. In the case of spontaneous recovery described (2), the person clearly stated that she wanted no active intervention in the event of brain injury yet 10 years later made a reasonable recovery. From a personal view point I would not be able to accept any interventions to prolong life in such a state. Much more needs to be done into the research of the best management of such patients but there is little funding to do so.”

Professor Marwan Hariz, Head of the Unit of Functional Neurosurgery, Institute of Neurology, UCL, said:

“This groundbreaking paper should at least have had the honesty to quote similar studies performed on tens, if not hundreds of similar patients in Japan and in various European countries since the late 1960s. Instead, it appears as if the authors, who are otherwise very knowledgeable of deep brain stimulation and its applications, are acting as pioneers, since they have chosen to completely neglect extensive published work published over the last 40 years, analysing the effect of deep brain stimulation in the thalamus and elsewhere, in patients with various types of post traumatic coma. While the authors should be congratulated on their study published here, they ought to as soon as possible correct this serious mistake.”