Deep Brain Stimulation Offers Hope for MCS
A 38-year old man in a minimally conscious state (MCS) from a closed head injury experienced improvement following deep brain stimulation of the midline and adjacent thalamic nuclei. The individual was six years post injury and was inconsistently responsive. His MRI showed right frontal encephalomalacia and a right thalamic infarct. A functional PET scan showed preservation of his language areas. A titration of deep brain stimulation (DBS) was followed leading up to 12 hours per day. The individual maintained longer periods of eye contact, regained some functional use of objects and produced intelligible speech. He swallowed food and drank from a cup for the first time since his injury. Neuropsychological tests showed improvement when the DBS device was "on" and a decline when the device was "off".
This study was carefully designed to replace the arousing and cohering effects on the cortex of the thalamic reticular neurons. As our understanding of brain functions continues to enhance, studies of this kind can become more targeted. This individual was not in Persistent Vegetative State (PVS) and he had intact language areas. Other individuals with Diffuse Axonal Injury (DAI) may not be capable of transmitting signals to the cortex due to the damaged neural tracts and may not benefit from this approach. Studies of this type, while not generalizable to all severe brain injuries and disorders of consciousness continue to offer us hope for improvement.