In the setting of a stroke affecting the dominant hemisphere, aphasia is most likely due to occlusion of which artery?

• A. Anterior cerebral artery
• B. Middle cerebral artery
• C. Posterior cerebral artery
• D. Basilar artery

Answer: (B)

Language centers are located in the dominant hemisphere, and the blood supply to those lateral language areas comes mainly from the middle cerebral artery. When the MCA is occluded in the dominant hemisphere, the regions around Broca’s area (speech production) and Wernicke’s area (language comprehension) are deprived of blood, leading to aphasia. Most people have language dominance in the left hemisphere, so a left MCA stroke is a common cause of aphasia. In contrast, occlusion of the anterior cerebral artery tends to affect medial frontal regions and leg-related function rather than language, posterior cerebral artery occlusion affects visual areas, and the basilar artery supplies brainstem and cerebellar structures with different syndromes. Therefore, the artery most likely responsible for aphasia in a stroke affecting the dominant hemisphere is the middle cerebral artery.