Patients who survive catastrophic brain damage may be left permanently unaware—in the permanent vegetative state. Many doctors are likely to manage these patients at some point in their career.1 The diagnosis has been the subject of reports prepared by official bodies.2^–6 It has been defined as “a clinical condition of unawareness of self and environment in which the patient breathes spontaneously, has a stable circulation, and shows cycles of eye closure and opening which may simulate sleep and waking.”4 A wide range of causes has been reported, but head injury is probably the most common.5 6

The diagnosis of permanent vegetative state is of particular importance; once it has been made, active medical treatment may be stopped. In the leading English case of Bland in 1993, the House of Lords held that artificial nutrition and hydration (for example, feeding by percutaneous endoscopic gastrostomy tube) constituted medical treatment and that if a patient was permanently unaware of self and environment, it was lawful not to continue such medical treatment.7 Up to October 1998, court approval to stop active medical treatment had been given for 18 patients.

Criteria for diagnosing permanent vegetative state have been drawn up by various groups.2^–6 Although these criteria are the result of collective thought and wisdom, they are not always helpful in clinical practice. In contrast to the diagnosis of brain death, where a few specific clinical criteria can determine the state,8 the diagnosis of permanent vegetative state depends on providing evidence of a negative: a lack of awareness. The criteria developed have included incidental but irrelevant clinical observations (for example, response to ice water caloric testing4). Furthermore, they have failed to focus on the fundamental question of awareness, which has lead to difficulties in …