The Vegetative State Updated

Abstract

The vegetative state is characterized by the absence of awareness, voluntary or otherwise purposeful behavioral responses to external stimuli, and communication in the severely brain damaged. It is thought to result from an anatomical/functional disconnection between the brainstem and cortex as a result of diffuse axonal damage/impairment. Early assistance/rehabilitation and the logistic and medical/paramedical resources made available in the 1990s have improved survival and outcome. About 80% of posttraumatic patients recover consciousness (50–60% within 3–4 months and about 60% with good recovery at discharge) so long-term observation has become possible and changed our perspectives. Responsiveness to pain or emotional stimuli and brain processing at varying levels of functional complexity have been documented by advanced fMRI, PET, and electrophysiological studies. The evidence indicates retained regional connectivity and partial functional integrity in the absence of the integrative processes necessary to consciousness. Evolution into a minimally conscious state is common and preliminary to recovery and is observable even after 1–5 years. The boundaries between the vegetative and minimally conscious states are somehow blurred and experience suggests sequential phases in a recovery process, rather than independent conditions. Systematic investigation on the vegetative and minimal conscious states pathophysiology and a close revision of the nosographic and diagnostic criteria are warranted.