Disorders of consciousness

The vegetative state and other so-called disorders of consciousness present some of the most significant practical and ethical challenges in modern medicine. It is extremely difficult to assess residual cognitive function in these patients because their movements may be minimal or inconsistent, or because no cognitive output may be possible. In recent years, behavioral and neuroimaging techniques developed within the cognitive neurosciences have provided a number of new approaches for investigating these disorders, leading to significant advances in current understanding. In several cases, residual cognitive function and even conscious awareness have been demonstrated in patients who are assumed to be vegetative yet retain cognitive abilities that have evaded detection using standard clinical methods. In this article, I review these data, focusing primarily on the vegetative and minimally conscious states.