Giving the minimally conscious and locked-in a voice
Imagine finding yourself in a hospital bed. All around you, you hear doctors and family members saying that you are incapable of understanding them or making decisions, but you aren’t able to speak to tell them that in fact you can. Unfortunately, this nightmare scenario is a reality for thousands of people misdiagnosed as being in a coma. In fact, it is estimated that over 40 % of those diagnosed as being in a vegetative state are later reclassified as being at least minimally conscious. “Some people who appear to be in a coma may actually be conscious to some degree,” says Dr Christoph Guger, a researcher with the EU-funded ComAware project. “The challenge is differentiating patients who are in a coma from those in a minimally conscious state when, to the naked eye, they all appear unresponsive.” To make matters more challenging, a patient’s state-of-alertness may fluctuate throughout the course of a day. “If the assessment is given during a period of inactivity, that patient could be misdiagnosed as being in a coma even when their brain is active the rest of the day,” adds Dr Guger. “Yet this misdiagnosis will form the basis of their treatment for months – even years – to come.” To give medical professionals the means to make a more accurate diagnosis, the ComAware project has developed a brain-computer interface (BCI) system called mindBeagle. BCI systems detect brain activity using electroencephalography (EEG) and interpret the meaning of any detected activity via machine-learning algorithms. “This system has the potential to allow patients to make their own decisions and interact with their environments by answering yes/no questions,” says Dr Guger. The mindBeagle system Using auditory and vibro-tactile stimulation to elicit typical brain responses, mindBeagle gives people in locked-in syndrome or those in unresponsive wakefulness states the ability to answer yes-or-no questions using only their thoughts. The patient simply wears an EEG cap containing 16 electrodes that are attached to their scalp. Vibration motors are also placed in each hand, where they deliver subtle vibrations. Next, the patient is asked to respond to yes-or-no questions. To answer, they focus on their hands – left for ‘yes’ and right for ‘no’ – activity that the EEG cap is able to detect as p300 brain waves. The algorithms then identify these brain waves and associates them with either the left or right hand, flashing the corresponding answer on a computer screen. Important results During testing, 9 out of 12 locked-in and 2 out of 10 unresponsive patients were able to answer yes/no questions correctly. “This is an extremely important result, first and foremost because the family gets objective proof that their loved one understands them, motivating them to visit more regularly,” says Dr Guger. “It is also important for medical professionals as it gives them better insight into whether or not the patient will ever fully ‘wake up’.” Most importantly, however, it is the patient who benefits from improved treatment and the ability to communicate their thoughts with others. “For this reason alone, every single patient presenting a disorder of consciousness should be treated with such a system,” adds Dr Guger.
ComAware, mindBeagle, coma, vegetative state, minimally conscious, brain-computer interface (BCI), electroencephalography