When a person enters a persistent vegetative state, she has no knowledge of her surroundings and is unable to communicate or react to situations voluntarily. Unlike someone in a coma, a person in a persistent vegetative state can still be considered alert. The brain of a patient in a vegetative state is not dead, as the brain stem is still fully functioning. In order to be considered in a persistent vegetative state, someone must be in a vegetative state for a least a month.
Several conditions can lead to a persistent vegetative state, including trauma or injury to the brain. A person can end up in a vegetative state after a gunshot wound or after an automobile accident. Some children are born with brain injuries. A vegetative state can also occur if someone is suffocated or almost drowns. Infections such as meningitis can also cause a vegetative state if not treated properly. A condition that causes a person's brain to degenerate over time, such as Alzheimer's or Parkinson's disease, can also lead to a persistent vegetative state as the disease progresses.
When in a persistent vegetative state, a person cannot speak or understand that he is being spoken to. He usually is incontinent, as he cannot control his muscles. Usually, a person in a vegetative state will need a feeding tube but will be able to breathe without a respirator.
A patient in a vegetative state cannot feel pain. She will most likely not notice that she is hungry or thirsty. Patients will react to stimuli, though. For instance, if a patient in a vegetative state is poked or pinched, she will most likely move involuntarily in response to the poke or pinch.
Patients in a persistent vegetative state will open and close their eyes. They will still fall asleep and wake up. When awake, they may follow objects with their eyes as if aware of what is going on. Even though a patient may be awake, there will be no activity in the brain.
While some patients may come out of a vegetative state after a month, if someone remains in a persistent vegetative state for longer than one year, the odds of him ever regaining the ability to speak, walk, and be conscious are very low. Patients who do come out of the vegetative state may have permanent disabilities. Usually, patients in a vegetative state do not survive for longer than five years.