“…The pathogenesis remains unknown and several theories have been proposed; it could be due to high intracranial pressure with partial venous obstruction leading to deep distension of the medullary vein, to preferential preservation of blood flow in the posterior circulation compared to the anterior circulation partial relief of elevated intracranial pressure by transtentorial herniation, other explanations include preserved brain tissue, petechial hemorrhage, and mineralized neurons for high-density areas on CT, and severe edema and/or tissue destruction for low-density areas on CT. Although the white sign may be discrete on imaging its recognition is essential because lumbar punctures may result in downward herniation due to a pressure gradient between the supra- and subtentorial compartments [2] , [3] , [4] , [5] , [6] .…”