by using 1927 Egas Moniz, mentor of neurology in Lisbon and Nobel Prize for Physiology or Medicine in 1949, released cerebral angiography, Whereby both normal and abnormal blood vessels in and round the brain could be visualized with great accuracy. In its early days this method likewise carried both immediate and long term risks, Many of them referable to deleterious effects of the positive contrast substances that were used for injection into the circulation. Techniques have become very refined in recent decades, With one in 200 patients or less experiencing ischemic sequelae from the