Increasing systolic and pulse pressure with bradycardia and respiratory irregularity are signs of increased intracranial pressure, leading to cerebral herniation and fatal brainstem compression. This phenomenon, the vasopressor response, is generally known as the Cushing reflex based on Harvey Cushing's experimental work in Europe in 1901 and 1902. However, similar experiments had been carried out decades earlier by others, notably Paul Cramer, Ernst von Bergmann, Ernst von Leyden, Georg Althann, Friedrich Jolly, Friedrich Pagenstecher, Henri Duret, Bernard Naunyn, and Julius Schreiber. Cushing initially failed to give credit to the work of these predecessors. Nonetheless, he studied the brain's reaction to compression more carefully than previous researchers and offered an improved explanation of the pathophysiology of the phenomenon named after him.