Delirium's an acute and relatively sudden (developing over hours to days) decline in attention-focus, perception, and cognition. Bickerstaff defines delirium as a state in which the patient appears out of touch with his surroundings and's spontaneously producing evidence of his confusion and disorientation by muttering, rambling, shouting, often offensively and continuously, with evidence of delusion and hallucination, and often with so much associated motor activity that physical exhaustion o… (More on Delirium)