Question
A
62-year-old man with
hypertension and atrial fibrillation is brought to the emergency department because of sudden onset visual changes. He stopped taking all of his medications
2 months ago. Blood pressure is
170/90 mm Hg and pulse is
108/min. He is alert and oriented to person but
does not follow commands. His speech is
fluent with normal cadence, but he uses frequent
non-existent words and the
content of his speech is nonsensical. He appears unaware of his speech impairment. He is unable to read a text out loud. Peripheral vision is diminished in the
right upper visual fields bilaterally. This patient’s presentation is most consistent with injury to which of the following labeled areas?
Show Answer
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Correct Answer � E
Explanation
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This patient’s receptive aphasia, right upper homonymous quadrantanopsia, and CVA risk factors are concerning for stroke secondary to occlusion of the inferior division of the left MCA.
Region A corresponds with the hippocampus, which is involved in the limbic system and is important for memory formation; it is supplied by the posterior cerebral artery and is particularly vulnerable to ischemia. Ischemic stroke involving the hippocampus would result in anterograde amnesia rather than the fluent aphasia and visual field defects seen in this patient.
Region B corresponds with the internal capsule and is a common site of lacunar infarcts, which classically present with contralateral hemiparesis or hemiplegia; dysarthria and dysphagia may also be present. This patient has significant risk factors for a lacunar infarct (e.g., age and unmanaged hypertension), but his receptive aphasia and right upper homonymous quadrantanopsia are not consistent with an internal capsule infarct.
Region C corresponds with the insula, a complex structure involved in perception, somatosensory processing, visceromotor functions, and cognition. Ischemic injury to this region is extremely rare and can have variable presentation, including vestibular, motor, somatosensory, speech, and/or cardiac conduction abnormalities. Insular strokes are most commonly associated with nonfluent aphasia; the combination of a fluent, receptive aphasia and right upper homonymous quadrantanopsia in this patient is not consistent with an insular stroke.
Region D corresponds with the inferior frontal gyrus, which is an important region for language and comprehension and is supplied by the superior division of the MCA. Ischemic stroke involving the inferior frontal gyrus classically presents with Broca aphasia, which is characterized by nonfluent speech deficits and relative sparing of comprehension. This patient has evidence of fluent aphasia, making injury to the inferior frontal gyrus unlikely.
The patient’s presentation of Wernicke aphasia and right upper homonymous quadrantanopsia is most consistent with an ischemic injury to the superior temporal gyrus (region E) due to an ischemic stroke involving the inferior division of the left MCA. His visual field deficits are the result of the involvement of the inferior fascicle of the left optic radiations (Meyer loop) in the temporal lobe. His atrial fibrillation and medical noncompliance suggest a thromboembolic stroke as the underlying cause.
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