Each day, ten individuals across the United Kingdom enter a coma as a result of a blow to the head (also known as a traumatic brain injury, or TBI). Patients in coma are unresponsive to external stimulation and breathe with support from a mechanical ventilator. A significant proportion of coma survivors will develop a prolonged disorder of consciousness (PDOC), such as the vegetative state, in which they appear to be awake but show no signs of being aware of themselves or of their environments. However, if a patient with a PDOC is able to move in response to verbal commands (e.g. “Give me a thumbs-up”) they are considered to be at least minimally conscious. Once this ability has been identified, rehabilitation can focus on training the individual to use this action to communicate (e.g. “Thumbs-up for yes”).
More accurate methods for predicting the level of recovery after coma are required. Electroencephalography, or EEG, is a portable form of brain-imaging that records the tiny electrical signals generated by the brain via a series of electrodes placed on the scalp. By measuring the brain’s response to external stimuli, it may be possible to improve the accuracy of prognosis in coma (i.e. predicted level of recovery).
We will test the predictive power of EEG responses to speech in a group of post-traumatic patients recovering from coma who do not immediately regain consciousness after withdrawal of sedation. During the year after this assessment, we will determine each patient’s level of recovery through interviews and, in some cases, a further EEG assessment and multiple behavioural assessments. The more accurate methods of prognosis that come from this research will result in more appropriate provision of limited rehabilitation resources post-coma, thereby reducing healthcare costs.