Persistent vegetative state

**Definition:** Subacute or chronic state of severe disturbance of consciousness lasting at least a month, characterised by the recovery of cyclic arousal states mimicking sleep/wake cycles after a severe brain injury. Patients with this condition are unresponsive and show no evidence of awareness of themselves or their environment. Cardiopulmonary and visceral autonomic regulation is maintained by the brainstem.

**Long definition:** Patients in a vegetative state are awake but are unaware of self or of the environment. The authors of the article "Persistent vegetative state after brain damage. A syndrome in search of a name. Lancet. 1972, Jennett and Plum, cited the Oxford English Dictionary to clarify their choice of the term "vegetative": to vegetate is to "live merely a physical life devoid of intellectual activity or social intercourse" and vegetative describes "an organic body capable of growth and development but devoid of sensation and thought". Persistent vegetative state has been arbitrarily defined as a vegetative state still present one month after acute traumatic or non-traumatic brain damage but does not imply irreversibility. Permanent vegetative state denotes irreversibility. The Multi-Society Task Force on PVS concluded that three months following a non-traumatic brain damage and 12 months after traumatic injury, the condition of VS patients may be regarded as 'permanent'. These guidelines are best applied to patients who have suffered diffuse traumatic brain injuries and post anoxic events; other non-traumatic aetiologies may be less well predicted and require further considerations of etiology and mechanism in evaluating prognosis. Even after these long and arbitrary delays, some exceptional patients may show some limited recovery. Particularly patients suffering non-traumatic coma without cardiac arrest who survive in vegetative state for more than three months. The diagnosis of vegetative state should be questioned when there is any degree of sustained visual pursuit, consistent and reproducible visual fixation, or response to threatening gestures, but these responses are observed in some patients who remain in vegetative state for years. It is essential to establish the formal absence of any sign of conscious perception or deliberate action before making the diagnosis.