Causes by diffuse cortical damage.
Patients appear awake, have sleep wake cycles.
The may suck and chew food and turn head toward stimuli and may weep.
Cannot eat, are incontinent, and show no evidence of understanding or complex behaviors.
poor meaningful prognosis for recovery when:
Traumatic etiology lasting >12 months; Young adults may recover after prolonged periods;
Cardiac arrest with PVS> 72 hours;
Metabolic causes with PVS > 3 months