An analysis of the brainwaves of 104 people with brain injury, all of whom did not respond to spoken commands to move, has concluded that 15% are hearing and trying to process commands despite not showing any physical movement.

Half of the 16 patients whose brainwaves showed a response via EEG were able to respond physically by the time they were discharged from the hospital and 44% were able to function independently for eight-hour periods one year after their injury, researchers reported in the New England Journal of Medicine.

By comparison, among the 88 patients whose EEGs did not show a response to spoken commands, only 26% were able to comply before they were discharged and just 14% were functioning independently by the 12-month mark.

In ICU patients with acute brain injury, “prediction of recovery is quite challenging and often inaccurate”, said lead author Dr Jan Claassen, medical director of the neurological intensive care unit at Columbia University’s Neurological Institute in New York.