The term covering abnormal brain function without infection (see ENCEPHALITIS) in which there are signs of cerebral irritation from numerous possible causes. Examples are HYPERTENSIVE ENCEPHALOPATHY, SPONGIFORM ENCEPHALOPATHY, WERNICKE'S ENCEPHALOPATHY and lead encephalopathy. In the first, which occurs in the later stages of chronic GLOMERULONEPHRITIS, or URAEMIA, the headache, convulsions and delirium which constitute the main symptoms are likely to be due to a deficient blood supply to the brain.