Patients suffering from locked-in syndrome similar could one day be able to communicate with a new mind-reading cap which is small enough to use at home.
Experts at Western University in London, Canada, have devised a device for measuring brain signals by using electrodes contained in the cap, reported New Scientist.
The two devices produced so far represent a breakthrough by being much smaller than conventional fMRI scanners, which are too bulky for most patients' homes. It is hoped the new caps will boost quality of life by allowing disabled users to communicated with loved ones and friends.
By measuring brain activity, the new mind reading caps could potentially aid diagnosis by showing doctors if a patient is conscious and not unconscious in a persistent vegetative state, thereby cutting the risk of misdiagnosis.
Being locked-in means patients are aware of stimuli, such as voices, but are incapable of responding in any way. Formula One Michael Schumacher is reportedly in a similar condition, after suffering catastrophic head injuries in a ski crash. He is said to have wept at the sound of his children's voice and can only communicate using one eyelid.
Adrian Owen of Western University said: "The possibility is that we are missing people with some sort of complete locked-in syndrome."
Owen estimated up to 20% of patients diagnosed as being in a vegetative state actually have some levels of consciousness.
With the new portable mind-reading device, vibrating pads are placed on the arm of a patient who then focuses their attention on one or another pad, as they answer yes-or-no questions.
"I think we may be able to send people home with some variation of an EEG. We will get there," Owen told a conference in London.