Bit · Neuro
Stroke Syndromes by Vessel — MCA, ACA, PCA, PICA, Lacunar
Eight stroke syndromes mapped to specific arteries. The vessel determines which territory dies and which deficit follows.
Mechanism
Knowing the territory each artery supplies maps directly onto the neurologic exam findings:
- MCA (middle cerebral artery) — lateral cortex, motor strip arm + face, language (dominant), neglect (non-dominant).
- ACA (anterior cerebral) — medial frontal cortex; motor strip leg.
- PCA (posterior cerebral) — occipital cortex (vision) + medial temporal lobe.
- Lenticulostriate (deep MCA branches) — internal capsule, basal ganglia → pure motor lacune.
- Basilar artery — pons, midbrain → locked-in syndrome if extensive.
- PICA (lateral medullary, Wallenberg) — lateral medulla.
- AICA (lateral pontine) — lateral pons.
- Anterior spinal — medial medulla (medial medullary syndrome).
Differentiator Table
| Artery | Territory | Deficits | Distinguishing features |
|---|---|---|---|
| MCA | Lateral cortex | Contralateral face + arm > leg weakness/sensory loss; aphasia (dominant L); neglect (non-dominant R) | Dominant: Broca (motor, frontal) vs Wernicke (receptive, temporal) |
| ACA | Medial frontal | Contralateral leg > arm weakness/sensory loss; urinary incontinence; abulia | Leg dominates because medial motor strip is leg homunculus |
| PCA | Occipital + medial temporal | Contralateral homonymous hemianopia with macular sparing; alexia without agraphia (dominant) | Macular sparing because of dual blood supply |
| Lenticulostriate | Internal capsule / basal ganglia | Pure motor lacune (face + arm + leg, no cortical signs) | HTN-related; multiple lacunes → vascular dementia |
| Basilar | Pons/midbrain | Quadriplegia, dysarthria, dysphagia, eye-movement palsies; consciousness preserved | Locked-in syndrome if pontine pontine; eye blinks/vertical gaze intact |
| PICA (Wallenberg) | Lateral medulla | Ipsilateral facial sensory loss + Horner; CONTRAlateral body sensory loss; dysphagia; vertigo; ataxia | 'Don't Pick a Horse that can't eat' |
| AICA | Lateral pons | Similar to PICA + IPSILATERAL facial PARALYSIS + ipsilateral hearing loss | |
| Anterior spinal | Medial medulla | Contralateral arm + leg weakness; contralateral medial-lemniscus sensory loss; IPSILATERAL tongue deviation (CN XII) |
The Pivot
Three steps to localize any stroke:
- Cortical or subcortical? Aphasia/neglect/visual field cut/sensory loss → cortical. Pure motor or pure sensory → lacunar (subcortical).
- Which limb is weaker? Face + arm > leg → MCA. Leg > arm → ACA.
- Posterior circulation? Vertigo, diplopia, dysarthria, dysphagia, ataxia → vertebrobasilar. Cranial nerve findings localize.
NBME-Style Stem
A 68-year-old man with atrial fibrillation suddenly develops vertigo, hoarseness, and difficulty swallowing. Examination shows loss of pain and temperature sensation on the LEFT side of the face and the RIGHT side of the body, an ipsilateral Horner syndrome, and a left-beating nystagmus. Which artery is most likely occluded?
Concept Anchor
Each cerebral artery owns a specific territory of brain — and the deficit you find on exam tells you which artery just stopped flowing. Cortical signs put it cortically; pure motor/sensory deficits put it deep; brainstem signs put it posterior.