Mastering Medical
USMLE Step 1 · Neurology

MCA stroke vs ACA and PCA strokes

How to tell MCA stroke and ACA and PCA strokes apart when a board question makes them look alike.

Fastest separator

MCA: face and arm weakness with aphasia or neglect; ACA: leg weakness; PCA: homonymous hemianopia with macular sparing.

Side by side

MCA strokeACA and PCA strokes
Key clue

Middle cerebral artery stroke causes contralateral face/arm weakness and sensory loss, aphasia if dominant hemisphere, neglect if nondominant, and possible homonymous hemianopia.

Anterior cerebral artery stroke causes contralateral leg-predominant weakness/sensory loss, abulia, or urinary incontinence; posterior cerebral artery stroke causes contralateral homonymous hemianopia with possible macular sparing.

Mechanism

MCA supplies lateral frontal, parietal, and temporal cortex including face/arm motor-sensory areas and language cortex in the dominant hemisphere.

ACA supplies medial frontal/parietal cortex including leg area; PCA supplies occipital cortex and inferior temporal/thalamic regions.

Labs and tests

Face-arm greater than leg deficits, aphasia, neglect, or gaze preference supports MCA territory stroke.

Leg greater than arm deficits support ACA; isolated visual field loss or cortical blindness supports PCA.

The trap

All are cortical strokes, so body-region emphasis and cortical function localize the artery.

Watch it explained

Test it now

The repair move

Map the deficit to the territory in three steps: (1) face and arm dominant deficit with cortical signs equals MCA; (2) leg-dominant deficit with frontal behavior or incontinence equals ACA; (3) isolated visual field loss or cortical blindness equals PCA. Any crossed deficit (ipsilateral cranial nerve plus contralateral body) is brainstem, never cortical territory.

Try a free question

Core

A right-handed patient has sudden right face and arm weakness greater than leg weakness plus expressive aphasia. Which artery territory is most likely affected?

Show answer and explanation

Answer: A. Left MCA. Dominant MCA stroke causes aphasia with contralateral face/arm-predominant deficits.

Why the other choices are tempting

  • B. ACA stroke causes leg-predominant deficits.
  • C. PCA stroke causes visual field deficits more than face/arm aphasia pattern.
  • D. Right PCA would not cause dominant aphasia in a right-handed patient.
  • E. Basilar artery stroke causes brainstem findings, not isolated dominant MCA cortex signs.

Flashcards

Tap a card to flip it.

What motor pattern points to MCA stroke?

Face and arm weakness greater than leg weakness points to MCA stroke.

What dominant-hemisphere clue points to MCA stroke?

Aphasia points to dominant MCA territory.

Quick answers

What is the fastest way to tell MCA stroke from ACA and PCA strokes?

MCA: face and arm weakness with aphasia or neglect; ACA: leg weakness; PCA: homonymous hemianopia with macular sparing.

What is the key clue for MCA stroke?

Middle cerebral artery stroke causes contralateral face/arm weakness and sensory loss, aphasia if dominant hemisphere, neglect if nondominant, and possible homonymous hemianopia.

What is the key clue for ACA and PCA strokes?

Anterior cerebral artery stroke causes contralateral leg-predominant weakness/sensory loss, abulia, or urinary incontinence; posterior cerebral artery stroke causes contralateral homonymous hemianopia with possible macular sparing.

What is the common trap with MCA stroke vs ACA and PCA strokes?

All are cortical strokes, so body-region emphasis and cortical function localize the artery.