The term 'state of prolonged unconsciousness' can be summarized as a COMA, which is a medical condition in which a person is unresponsive and has minimal brain activity for an extended period of time. It is usually caused by a traumatic brain injury, stroke, or other medical conditions. COMA patients may show some reflexive responses to stimuli, but are unable to respond to commands or communicate. Treatment for a COMA depends on the cause and severity of the condition.