An altered brain state that can occur with altered brain structure. Many etiologies are associated with encephalopathy (toxins, cancer, metabolic disorders, CNS infections, increased cranial pressure, radiation, alcohol, psychotropic drugs, trauma, inadequate nutrition, decreased brain oxygen, and CNS injury). Consciousness is impaired with patients having a decreased/altered mental state and diffuse slowing of the EEG. Encephalopathy is often associated with seizures, loss of cognitive/memory, and personality changes, and can be associated with myoclonus and other neurologic impairments.