Laminar necrosis and watershed infarcts are most suggestive of

Decreased brain perfusion may be generalized (global) or localized. Global ischemia results from generalized decreased blood flow, such as with shock, cardiac arrest, or hypoxic episodes (e.g., near drowning or carbon monoxide poisoning). Global hypoxia results in watershed (border zone) infarcts, which typically occur at the border of areas supplied by the anterior and middle cerebral aeries, and laminar necrosis, which is related to the sho, penetrating vessels originating from pial aeries. The Purkinje cells of the cerebellum and the pyramidal neurons of Sommer's sector in the hippocampus are paicularly sensitive to hypoxic episodes. Atherosclerosis, which predisposes to vascular thrombi and emboli, is related to regional ischemia. Hypeension damages parenchymal aeries and aerioles, producing small ischemic lesions (lacunar infarcts). Fat emboli, related to trauma of long bones, lodge in small capillaries to form petechiae. Venous sinus thrombosis is related to systemic dehydration, phlebitis, and sickle cell disease. Ref - Harrison's internal medicine 20e pg 1117, 2039-2040