Many patients emerge spontaneously from a vegetative state within a few weeks.[6] The chances of recovery depend on the extent of injury to the brain and the patient's age younger patients having a better chance of recovery than older patients. Generally, adults have a circa 50 percent chance and children a 60 percent chance of recovering consciousness from a PVS within the first 6 months in the case of traumatic brain injury. For non-traumatic injuries such as strokes, the recovery rate falls to 14% at one year.[21] After this period the chances that a PVS patient will regain consciousness are very low and most patients who do recover consciousness experience significant disability. The longer a patient is in a PVS, the more severe the resulting disabilities are likely to be. Rehabilitation can contribute to recovery, but many patients never progress to the point of being able to take care of themselves. Recovery after long periods of time in a PVS has been reported on several occasions and is often treated as a spectacular event.[citation needed]
There are two dimensions of recovery from a persistent vegetative state: recovery of consciousness and recovery of function. Recovery of consciousness can be verified by reliable evidence of awareness of self and the environment, consistent voluntary behavioral responses to visual and auditory stimuli, and interaction with others. Recovery of function is characterized by communication, the ability to learn and to perform adaptive tasks, mobility, self-care, and participation in recreational or vocational activities. Recovery of consciousness may occur without functional recovery, but functional recovery cannot occur without recovery of consciousness (Ashwal, 1994).