A 70-year-old woman with a history of unilateral extremity weakness and seizures is found unresponsive at home by her home health care nurse. On arrival of emergency medical services, she is found to have no pulse or spontaneous respirations and is declared dead. Autopsy shows a large thrombus occluding the left anterior descending coronary artery. Additional cerebral findings are shown in the exhibit.
Which of the following most accurately describes the pathogenesis of this patient's brain lesion?

Question

A 70-year-old woman with a history of unilateral extremity weakness and seizures is found unresponsive at home by her home health care nurse.  On arrival of emergency medical services, she is found to have no pulse or spontaneous respirations and is declared dead.  Autopsy shows a large thrombus occluding the left anterior descending coronary artery.  Additional cerebral findings are shown in the exhibit. 
 Which of the following most accurately describes the pathogenesis of this patient's brain lesion?

Quizplus · Accepted Answer

11ec160b_39d4_ee37_9249_6333476d1d20_MD0001_00 The autopsy image shows a coronal section of the brain with evidence of past necrosis (eg, cystic cavity, volume loss, and enlarged ventricle). These findings are consistent with an old cerebral infarct, which was likely responsible for this patient's chronic neurologic symptoms (eg, extremity weakness and seizures). Interruption in blood supply to an area of the brain, such as by thrombosis or embolism, induces irreversible ischemic changes in neurons. Release of lysosomal enzymes from ischemic neurons and responding inflammatory cells (eg, neutrophils, macrophages) results in tissue degradation in the affected region (liquefactive necrosis). Over time, phagocytic cells remove the necrotic tissue, leaving a cavity, while astrocytes proliferate around the periphery to form a scar (gliosis). Liquefactive necrosis is characteristic of irreversible CNS injury because of the brain's high cholesterol content and lack of supporting architecture. It also occurs in other body tissues in the setting of severe infection/inflammation (eg, bacterial abscess, fungal infection) because of the release of hydrolytic enzymes from reacting inflammatory cells. (Choice A) Early fibroblast migration to an area of injury occurs outside of the CNS and results in the formation of granulation tissue and fibrous scarring. In the CNS, tissue repair and scar formation are performed by astrocytes. (Choice B) A granulomatous reaction against parasites within the CNS occurs in neurocysticercosis. However, multiple cystic lesions or residual calcified granulomas would be expected. (Choice C) Multiple sclerosis is a chronic inflammatory demyelinating disease characterized grossly by multiple periventricular lesions (ie, demyelinating plaques). Cystic cavity formation does not occur. (Choice D) Although glioblastoma multiforme can present with areas of cystic necrosis on gross examination, these areas classically are part of a diffuse, poorly delineated, heterogenous mass with midline shift away from the affected tissue. Educational objective: Liquefactive necrosis is characterized by complete digestion and removal of necrotic tissue with formation of a cystic cavity. Irreversible ischemic CNS injury is typically followed by liquefactive necrosis due to the release of lysosomal enzymes from inflammatory cells and damaged neurons.

A 70-Year-Old Woman with a History of Unilateral Extremity Weakness