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The patient was diagnosed with a pure sensory stroke and received appropriate treatment. Her symptoms improved, and she returned home to live with her daughter after a few weeks of physical rehabilitation. Five years later, the patient dies of a large myocardial infarction. On autopsy, there are two 5- to 6-mm cavities in the deep structures of her brain filled with clear fluid. Which of the following processes is most likely responsible for the patient's brain findings?
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Lacunes are small (<15 mm) cavitary infarcts located within the basal ganglia, posterior limb of the internal capsule, pons, and cerebellum. The infarcts result from occlusion of the small penetrating arteries that supply these deep brain structures (eg, lenticulostriate arteries), most commonly in the setting of chronic uncontrolled hypertension or diabetes mellitus.
Lipohyalinosis and microatheromas are believed to be the primary causes of lacunar infarcts. Lipohyalinosis occurs secondary to leakage of plasma proteins through damaged endothelium and is characterized by hyaline thickening of the vascular wall, collagenous sclerosis, and accumulation of mural foamy macrophages. Microatheromas result from atherosclerotic accumulation of lipid-laden macrophages within the intimal layer of a penetrating artery near its origin off the parent vessel. These changes predispose to small-vessel occlusion and infarction of CNS tissue with liquefactive necrosis and the formation of a fluid-filled cavity.
(Choice A) Multiple sclerosis is an autoimmune demyelinating disease of the CNS. The CNS lesions in multiple sclerosis do not form cavities; instead, they appear grossly as pink patches in the white matter tracts.
(Choices B and C) Embolism due to carotid atherosclerosis or mitral valve disease (eg, bacterial endocarditis) most commonly causes cortical infarcts. Although small embolic fragments (ie, microemboli) released from atherosclerotic lesions or valvular disease may be the cause of some lacunar infarcts, lipohyalinosis/microatheromas are a much more common etiology.
(Choice E) Malignant neoplasms tend to cause space-occupying lesions rather than small cavities. The center of a large tumor may cavitate due to insufficient perfusion, with resultant necrosis and hemorrhage.
Educational objective:
Lacunar infarctions are the result of small-vessel occlusion (due to lipohyalinosis and microatheroma formation) in the penetrating vessels supplying the deep brain structures. Uncontrolled hypertension and diabetes mellitus are major risk factors for this condition.