Which vascular territory is most likely affected in a stroke presenting with contralateral leg weakness greater than arm weakness and incontinence?

Which vascular territory is most likely affected in a stroke presenting with contralateral leg weakness greater than arm weakness and incontinence?

• A. Anterior cerebral artery
• B. Middle cerebral artery
• C. Posterior cerebral artery
• D. Vertebrobasilar arteries

Answer: (A)

The main concept being tested is how stroke deficits map to vascular territories. When weakness is stronger in the contralateral leg than in the arm, and incontinence is present, the most likely culprit is an infarct in the medial motor cortex supplied by the anterior cerebral artery. The medial portion of the primary motor cortex (the paracentral lobule) controls movements of the opposite leg, so an ACA stroke tends to produce leg-dominant weakness. Disruption of the medial frontal circuits can also affect bladder control, leading to incontinence. By comparison, a stroke in the middle cerebral artery classically causes stronger weakness of the face and arm and may involve language deficits if the dominant hemisphere is affected; a posterior cerebral artery stroke often presents with visual field loss rather than leg-dominant weakness; and vertebrobasilar territory strokes produce brainstem or cerebellar signs rather than isolated leg weakness.

The main concept being tested is how stroke deficits map to vascular territories. When weakness is stronger in the contralateral leg than in the arm, and incontinence is present, the most likely culprit is an infarct in the medial motor cortex supplied by the anterior cerebral artery. The medial portion of the primary motor cortex (the paracentral lobule) controls movements of the opposite leg, so an ACA stroke tends to produce leg-dominant weakness. Disruption of the medial frontal circuits can also affect bladder control, leading to incontinence.

By comparison, a stroke in the middle cerebral artery classically causes stronger weakness of the face and arm and may involve language deficits if the dominant hemisphere is affected; a posterior cerebral artery stroke often presents with visual field loss rather than leg-dominant weakness; and vertebrobasilar territory strokes produce brainstem or cerebellar signs rather than isolated leg weakness.