A 58-year-old homeless man is brought to the emergency department after being found unresponsive on a sidewalk. The patient has been hospitalized on several occasions for alcohol and illicit drug intoxication. He also has a history of hypertension but is not adherent with medical therapy. On arrival, the patient is obtunded, febrile, and hypotensive. Physical examination reveals lung crackles and a new blowing diastolic murmur consistent with aortic regurgitation. Appropriate treatment is started, but the patient dies several days later. Autopsy examination shows symmetric, bilateral wedge-shaped strips of necrosis over the cerebral convexity, parallel and a few centimeters lateral to the interhemispheric cerebral fissure. Which of the following is the most likely cause of this patient's cerebral findings?

Question

A 58-year-old homeless man is brought to the emergency department after being found unresponsive on a sidewalk.  The patient has been hospitalized on several occasions for alcohol and illicit drug intoxication.  He also has a history of hypertension but is not adherent with medical therapy.  On arrival, the patient is obtunded, febrile, and hypotensive.  Physical examination reveals lung crackles and a new blowing diastolic murmur consistent with aortic regurgitation.  Appropriate treatment is started, but the patient dies several days later.  Autopsy examination shows symmetric, bilateral wedge-shaped strips of necrosis over the cerebral convexity, parallel and a few centimeters lateral to the interhemispheric cerebral fissure.  Which of the following is the most likely cause of this patient's cerebral findings?

Quizplus · Accepted Answer

11ec160b_39ca_b5f8_9249_bd4ffaffaf1a_MD0001_00 This patient with a history of drug use developed fever and new-onset aortic regurgitation, which are suggestive of endocarditis. His pulmonary edema (crackles) and hypotension are due to subsequent cardiogenic shock. On autopsy, the symmetric, bilateral wedge-shaped strips of necrosis over the cerebral convexity are characteristic of global cerebral ischemia. Profound systemic hypotension (eg, cardiogenic shock, cardiopulmonary arrest) diminishes blood supply to the entire brain, resulting in neuron cell death in areas that are vulnerable to hypoxia. This includes brain regions with high metabolic demand (eg, hippocampus, cerebellar Purkinje cells) and areas supplied by the distal-most branches of cerebral arteries (watershed zones). These border zones are located between areas supplied by the anterior, middle, and posterior cerebral arteries and are vulnerable because of low baseline perfusion pressure. The resulting necrosis occurs in bilateral, wedge-shaped strips that can extend from the frontal to occipital lobe and are located parallel and a few centimeters lateral to the interhemispheric fissure. (Choice A) Cerebral amyloid angiopathy typically affects patients over the age of 70 and results in lobar hemorrhages (eg, occipital, parietal) rather than ischemia. Amyloidosis can also cause cardiomyopathy, although patients typically develop right-sided heart failure (eg, edema, ascites) rather than valvular insufficiency. (Choice B) Although infectious endocarditis frequently causes embolization of bacterial vegetations, cardiac embolism would likely cause multiple scattered infarcts in an asymmetric pattern within different major vascular territories (eg, middle and anterior cerebral artery). This patient's symmetric, bilateral infarcts correspond to the cortical watershed regions and are more suggestive of global cerebral ischemia. (Choice D) Charcot-Bouchard aneurysms form as a result of chronic hypertension, and a rupture causes intracerebral hemorrhage typically involving deep brain structures (eg, basal ganglia, cerebellar nuclei, thalamus, pons). (Choice E) Saccular aneurysms, which occur at areas of weakness in cerebral arteries, typically cause subarachnoid hemorrhage after a rupture rather than cerebral ischemia. Patients usually have sudden-onset severe (thunderclap) headache and meningismus. Educational objective: Sustained cerebral hypoperfusion (eg, hypotension, shock) may cause global cerebral ischemia and watershed infarction. These watershed zones are located at the borders between areas perfused by the anterior, middle, and posterior cerebral arteries and typically appear as symmetric, bilateral wedge-shaped strips of necrosis over the cerebral convexity, parallel and adjacent to the interhemispheric fissure. __________ References: Border zone infarcts: pathophysiologic and imaging characteristics (http://www.ncbi.nlm.nih.gov/pubmed/21918038)

A 58-Year-Old Homeless Man Is Brought to the Emergency Department