Stimulating consciousness

How can we help severely brain-damaged people to regain consciousness? Researchers from the University of Liège’s Coma Science Group showed that in some patients in a minimally conscious state, transcranial direct current stimulation encourages the recovery of cognitive and motor skills. But while 43 % of the patients in a minimally conscious state who were studied showed a temporary improvement, 57 % of them manifested no change at all. Furthermore, patients in a vegetative state/unresponsive wakefulness syndrome don’t benefit in any way from transcranial direct current stimulation. Why? Researchers from the Coma Science Group are currently trying to find an answer to this question. Publication in the journal, Neurology.

In general, a coma lasts several hours, several days or several weeks. As soon as the patient opens their eyes – if they have survived -, they abandon this state either to regain consciousness, albeit sometimes in the form of locked-in syndrome, or to enter into a vegetative/unresponsive or minimally conscious state.

Patients in coma show no voluntary behavioural response to stimulations from their environment and their sleep-wake cycles have disappeared. They never open their eyes, even after intense nociceptive stimulation.

Patients in a vegetative state/unresponsive wakefulness syndrome maintain the ability to open their eyes, as well as other autonomous functions, such as controlling their breathing. Their movements are involuntary and, although their eyes are open when in a state of wakefulness, they have no awareness of their environment. On the contrary, patients in a minimally conscious state have a fluctuating awareness of their environment and they may execute voluntary movements – visually following an object that is moving in space, smiling, respond to a simple command, etc. Nevertheless, they are incapable of communicating their thoughts to those around them.

Electric stimulations

Headset-stimulation-tDCSAs regards patients in a vegetative state/unresponsive wakefulness syndrome or in a minimally conscious state, specialised centres deploy different strategies to encourage a return to a state of consciousness worthy of this name, where the patient is able to communicate. Sometimes their limbs are mobilised, sometimes music therapy is applied, or sometimes the patient is placed in special light conditions...  "The problem is that none of these approaches have proven their effectiveness", points out Professor Steven Laureys, head of the Coma Science Group at the University of Liège (Cyclotron Research Centre and the Neurology Department at Liège’s university hospital). Of course, some patients recover, but it is incredibly difficult to show that the aftercare given contributed to their recovery.

To untangle this web, there is no other solution than to carry out randomised double-blind placebo-controlled studies. And yet, up until now, there has only been one study of this kind. Published in 2012 by Joseph Giacino’s team from the New Jersey Neuroscience Institute, it showed that by administering amantadine (a nonspecific drug that was initially used for Parkinson’s disease followed by multiple sclerosis) four weeks after coming out of a coma, there was some improvement in the cognitive and motor responses of patients in a vegetative/unresponsive state and a minimally conscious state.

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