Conscious is define as awareness of oneself and the environment. Consciousness can be divide into wakefulness (being awake) and awareness (being aware). When evaluating consciousness, neurologists determine that patients are awake when their eyes open spontaneously or when they open in response to a stimulus. Neurologists determine that patients have awareness if they are able to perceive a stimulus in their environment and make a response that requires the ability to think, such as holding up two fingers when asked to do so.
Unconscious is a state which occurs when the ability to maintain an awareness of self and environment is lost. It involves a complete or near-complete lack of responsiveness to people and other environmental stimuli.
Coma a medical term for state of deep unconsciousness or deep sleep. People who are in that state cannot be woken up even by pain or light. Coma patients exhibit a complete absence of wakefulness and are unable to consciously feel, speak or move. Coma can result from various conditions. Some of these are intoxication, poisons, damages or diseases of the nervous system. It can also be the result of certain drugs.
The three major disorders of consciousness are coma vegetative state, and minimally conscious state. In coma, which typically is present for the first one to two weeks after brain injury, patients are not awake or aware, meaning that they do not open their eyes, have only reflex responses and are unaware of those around them.
If a coma lasts more than two or three weeks, it evolves into the vegetative state. In this state, unlike coma, wakefulness is present, which means that patients’ eyes open either spontaneously or in response to stimulus. However, as in coma, awareness is not present. If the vegetative state persists for more than three to six months, the term persistent vegetative state is applied.
If patients recover from the vegetative state, a condition known as the minimally conscious state may occur. In this state, patients may have subtle or inconsistent purposeful responses, such as attempting to speak or reach out for something. Some of these patients continue to improve, but others remain in this state and have severe neurologic impairment.
Predicted chances of recovery will differ depending on which techniques were use to measure the patient’s severity of neurological damage. Predictions of recovery are based on statistical rates, expressed as the level of chance the person has of recovering. Time is the best general predictor of a chance of recovery. The outcome for coma and vegetative state depends on the cause, location, severity and extent of neurological damage. A deeper coma alone does not necessarily mean a slimmer chance of recovery, similarly, milder comas do not ensure higher chances of recovery .