Dr. Harvey Cushing is known as the "father of neurosurgery," given credit for laying the foundation upon which the whole field of brain surgery is built. At the time he began to concentrate on improving the results of brain surgery in the early 20th century, such surgery was nearly 100 percent fatal. As a result of removing a tumor from Gen. Leonard Wood, his study of the pituitary gland led to identification of what is known as Cushing's syndrome. Cushing's Law states that an increase in intracranial tension causes an increase in blood pressure. The blood pressure remains higher, however, than the intracranial pressure, thus preventing the brain from being shut off from its blood supply. His work by 1932 led to a reduction of the mortality rate in brain surgery to 10 percent.