Severe brain injuries lead to disorders of consciousness after coma. During this awakening
period, detection of arousal is critical to the adaptation of medical strategy, but global
paralysis, including facial expression, make the clinical assessment very difficult.
Emotional facial expressions are a significant part of this clinical assessment. They are
both a landmark of the internal state of the patient (comfort versus discomfort) and a
landmark of the relational level with his environment. Visible emotional facial expression is
a large temporal phenomenon lasting a couple of seconds, while a microexpression is barely
noticeable and very brief. These micro expressions are usually produced when one tried to
voluntary hide emotional expressions. In this study, we hypothesize that some patients
awakening from coma could still produce microexpression before being able to produce visible
emotional facial expressions. This ability to produce micro-expression could be an early
landmark of relational awakening in severe brain lesions.