Disorders of consciousness are medical conditions that inhibit consciousness.[1] Some define disorders of consciousness as any change from complete self-awareness to inhibited or absent self-awareness and arousal. This category generally includes minimally conscious state and persistent vegetative state, but sometimes also includes the less severe locked-in syndrome and more severe but rare chronic coma.[1][2] Differential diagnosis of these disorders is an active area of biomedical research.[3][4][5] Finally, brain death results in an irreversible disruption of consciousness.[1] While other conditions may cause a moderate deterioration (e.g., dementia and delirium) or transient interruption (e.g., grand mal and petit mal seizures) of consciousness, they are not included in this category.