DISORDERS OF CONSCIOUSNESS - DIFFERENTIAL-DIAGNOSIS AND NEUROPATHOLOGIC FEATURES

Disorders of consciousness present intriguing challenges to the neurol ogist and neurorehabilitation specialist. Assessment is constrained by the lack of reliable methods of assessing consciousness, and there ar e no treatment interventions known to influence the course of recovery from these conditions. In addition, the relationship between the clin ical features associated with these disorders and their corresponding pathophysiologic substrate is also unclear. Our understanding of disor ders of consciousness has not kept pace with the advances in neurosurg ical management that have decreased mortality following severe injury. There is still considerable confusion regarding differential diagnosi s and prognostication concerning states of severely altered consciousn ess, The purpose of this article is to discuss the content and neural basis of consciousness and to review the terminology most often used t o describe altered states of consciousness, The neurobehavioral criter ia for differentiating among specific syndromes associated with severe alterations in consciousness are presented. Representative case studi es are utilized to illustrate the characteristic clinical profiles of coma, vegetative state, persistent and permanent vegetative state, min imally conscious state, akinetic mutism, and locked-in syndrome. Areas of ambiguity and controversy are emphasized and future directions for research are suggested.