The diagnosis of a permanent vegetative state is made when a patient is found to be unaware of himself or herself and the environment and there is no prospect of any change in this state by any means. Although the clinical characteristics and diagnosis of the condition have been established, the clinical diagnosis is not easy as there is a spectrum from the vegetative state to full awareness. The border between these two states is referred to as the low awareness state. No absolute definition exists for low awareness state.
The diagnosis of a permanent vegetative state is made when a patient is found to be unaware of himself or herself and the environment and there is no prospect of any change in this state by any means. Although the clinical characteristics and diagnosis of the condition have been established, the clinical diagnosis is not easy as there is a spectrum from the vegetative state to full awareness. The border between these two states is referred to as the low awareness state. No absolute definition exists for low awareness state. Generally, however, the patient behaves in a way that implies that at times he or she may be able to extract meaning from a stimulus and may be able to respond in a goal directed way. Usually the state is intermittent, with only vegetative responses being present at other times. Rarely, it may be possible to establish some form of rudimentary communication. We do not know if patients have any day-to-day memory or appreciation of their situation or whether they can experience somatic or emotional pain or pleasure.
Diagnosis of permanent vegetative state
The patient shows no behavioural evidence of awareness of self or environment
There is brain damage, usually of known cause, consistent with the diagnosis
There are no reversible causes present and
At least six (and usually 12) months have passed since onset
See
Ethical Issues in Diagnosis and Management of Patients in the Permanent Vegetative State , British Medical Journal February 1, 2001