A persistent vegetative state (PVS) or post-coma unresponsiveness (PCU) is a disorder of consciousness in which patients with severe brain damage are in a state of partial arousal rather than true awareness. After four weeks in a vegetative state (VS), the patient is classified as being in a persistent vegetative state. This diagnosis is classified as a permanent vegetative state some months (three in the US and six in the UK) after a non-traumatic brain injury or one year after a traumatic injury. The term unresponsive wakefulness syndrome may be alternatively used, as "vegetative state" has some negative connotations among the public. Definition
There are several definitions that vary by technical versus laymans usage. There are different legal implications in different countries. Medical definition
Per the British Royal College of Physicians of London, a persistent vegetative state is "a wakeful unconscious state that lasts longer than a few weeks is referred to as a persistent (or continuing) vegetative state". "Vegetative state"
The vegetative state is a chronic or long-term condition. This condition differs from a coma: a coma is a state that lacks both awareness and wakefulness. Patients in a vegetative state may have awoken from a coma, but still have not regained awareness. In the vegetative state patients can open their eyelids occasionally and demonstrate sleep-wake cycles, but completely lack cognitive function. The vegetative state is also called a "coma vigil". The chances of regaining awareness diminish considerably as the time spent in the vegetative state increases.
In the US, courts have required petitions before termination of life support that demonstrate that any recovery of cognitive functions above a vegetative state is assessed as impossible by authoritative medical opinion. In England, Wales and Scotland, the legal precedent for withdrawal of clinically assisted nutrition and hydration in cases of patients in a PVS was set in 1993 in the case of Tony Bland, who sustained catastrophic anoxic brain injury in the 1989 Hillsborough disaster. An application to the Court of Protection is no longer required before nutrition and hydration can be withdrawn or withheld from PVS (or minimally conscious – MCS) patients.This legal grey area has led to vocal advocates that those in PVS should be allowed to die. Others are equally determined that, if recovery is at all possible, care should continue. The existence of a small number of diagnosed PVS cases that have eventually resulted in improvement makes defining recovery as "impossible" particularly difficult in a legal sense. This legal and ethical issue raises questions about autonomy, quality of life, appropriate use of resources, the wishes of family members, and professional responsibilities. Signs and symptoms
Most PVS patients are unresponsive to external stimuli and their conditions are associated with different levels of consciousness. Some level of consciousness means a person can still respond, in varying degrees, to stimulation. A person in a coma, however, cannot.