A 70-year-old, right-handed woman comes to the emergency department with a daylong history of vision disturbance and bumping into objects on the left side. She also has had a mild headache over the past several hours. Medical history includes hypertension, hyperlipidemia, and type 2 diabetes mellitus. Physical examination shows left homonymous hemianopia with macular sparing. Noncontrast CT of the head demonstrates an area of focal parenchymal hypoattenuation consistent with ischemic infarction, as shown in the image below:
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Which of the following additional examination findings is most likely to be present in this patient?
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This patient's CT findings are consistent with an ischemic stroke impacting the occipital cortex and thalamus, areas supplied by the posterior cerebral artery (PCA). The following are the most common deficits that occur with PCA strokes:
Homonymous hemianopia (± visual neglect), which occurs contralateral to the site of the lesion: The macula is often spared because of collateral circulation from the middle cerebral artery.
Paresthesia and hemisensory loss: The PCA supplies the lateral thalamus, in addition to the cortex. Damage to this area leads to contralateral hemisensory loss of the face, trunk, and limbs, impacting all sensory modalities (eg, touch, pinprick, vibration, proprioception).
A variety of cortical symptoms can also occur. These include alexia, visual agnosia (eg, impaired visual recognition of objects), and prosopagnosia (eg, inability to recognize faces).
(Choice A) Fluent aphasia is classically caused by lesions that impact Wernicke area, which is supplied by the inferior division of the middle cerebral artery.
(Choice C) Although hypotonia is most often associated with lower motor deficits, it can also be seen with lesions of the lateral cerebellar hemisphere because the cerebellum helps regulate baseline posture and muscle tone. This occurs ipsilateral to the side of the lesion.
(Choice D) Right-left disorientation can occur with damage to the dominant (usually left) parietal lobe. It most classically develops as a part of Gerstmann syndrome, which results from injury involving the angular gyrus.
(Choice E) Dysmetria (overshooting or undershooting during the finger-nose-finger test) is a neurologic examination sign of limb ataxia that localizes to the cerebellum. Deficits due to cerebellar dysfunction are typically ipsilateral to the site of the lesion.
Educational objective:
The most common findings with posterior cerebral artery stroke are contralateral homonymous hemianopia with macular sparing due to damage to the occipital cortex and contralateral hemisensory loss due to damage to the thalamus.