A 70-year-old right-handed woman comes to the emergency department with left-sided visual loss that she noticed on awakening in the morning. She has no headache, slurred speech, difficulty swallowing, weakness, or difficulty walking. Her other medical problems include hypertension, atrial fibrillation, and hyperlipidemia. Blood pressure is 170/102 mm Hg and pulse is 90/min and irregular. On neurologic examination, she is alert and oriented to person, place, and time. Her speech is fluent, and she follows complex commands. Examination of her visual fields shows left homonymous hemianopia with macular sparing. There is decreased sensation over the left side of her body. The remainder of the neurologic examination is within normal limits. Non-contrast head CT demonstrates an area of focal parenchymal hypoattenuation, as shown in the image below. Which of the following cerebral arteries is most likely to be compromised in this patient?

Question

A 70-year-old right-handed woman comes to the emergency department with left-sided visual loss that she noticed on awakening in the morning.  She has no headache, slurred speech, difficulty swallowing, weakness, or difficulty walking.  Her other medical problems include hypertension, atrial fibrillation, and hyperlipidemia.  Blood pressure is 170/102 mm Hg and pulse is 90/min and irregular.  On neurologic examination, she is alert and oriented to person, place, and time.  Her speech is fluent, and she follows complex commands.  Examination of her visual fields shows left homonymous hemianopia with macular sparing.  There is decreased sensation over the left side of her body.  The remainder of the neurologic examination is within normal limits.  Non-contrast head CT demonstrates an area of focal parenchymal hypoattenuation, as shown in the image below.  Which of the following cerebral arteries is most likely to be compromised in this patient?

Quizplus · Accepted Answer

11ec160b_35b6_65a4_9249_9d4a51af1b7e_MD0001_00 **(Axial images are interpreted as if viewed from the patient's feet, so the patient's right side is shown on the left side of the image.) This patient likely suffers from an embolic stroke due to her underlying atrial fibrillation. Non-contrast head CT demonstrates an area of focal parenchymal hypoattenuation and occipital horn effacement consistent with an evolving infarct in the distribution of the right posterior cerebral artery (PCA). The PCA branches off the basilar artery at the level of the pontomesencephalic junction and supplies cranial nerves III and IV and other structures in the midbrain. It also supplies the thalamus, medial temporal lobe, splenium of the corpus callosum, parahippocampal gyrus, fusiform gyrus, and occipital lobe. The most common finding in PCA territory infarction is contralateral hemianopia, often with macular sparing due to collateral circulation from the middle cerebral artery. Involvement of the lateral thalamus frequently results in contralateral paresthesias and numbness affecting the face, trunk, and limbs. A variety of cortical symptoms can also occur, including dyslexia, visual agnosia (eg, impaired visual recognition of objects), and prosopagnosia (eg, inability to recognize faces). (Choice A) The anterior cerebral artery distribution includes the inferior frontal, medial frontal, and superior medial parietal lobes; anterior 4/5 of the corpus callosum; olfactory bulb and tract; anterior portions of the basal ganglia; and internal capsule. (Choice B) The anterior choroidal artery is the last branch off the internal carotid artery before it trifurcates. It supplies the posterior limb of the internal capsule, optic tract, lateral geniculate body, choroid plexus, uncus, hippocampus, and amygdala. (Choice C) The artery of Percheron branches off either the right or left PCA and supplies the bilateral thalami and dorsal midbrain. It is considered to be a rare normal variant and can be seen in patients with bilateral thalamic or dorsal midbrain strokes. (Choice D) The basilar artery supplies a large portion of the brain, including most of the brainstem and bilateral cerebellar hemispheres. (Choice E) The middle cerebral artery distribution includes the lateral convexity of the frontal, parietal, and temporal lobes. It also supplies deep subcortical structures, such as the internal capsule and basal ganglia. Ischemic stroke occurs most frequently within this region, causing contralateral motor and sensory deficits involving the upper and lower extremities and face. Educational objective: The posterior cerebral artery branches off the basilar artery and supplies cranial nerves III and IV and other structures in the midbrain. It also supplies the thalamus, medial temporal lobe, splenium of the corpus callosum, and occipital lobe. The most common finding with posterior cerebral artery stroke is contralateral homonymous hemianopia, often with macular sparing. __________ References: Ischemic posterior circulation stroke: a review of anatomy, clinical presentations, diagnosis, and current management. (http://www.ncbi.nlm.nih.gov/pubmed/24778625)

A 70-Year-Old Right-Handed Woman Comes to the Emergency Department with Left-Sided