MCA stroke
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"middle cerebral artery" AND "ischemic stroke"
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Middle Cerebral Artery (MCA) Stroke
Anatomy & Territory
The MCA is the most common vessel involved in stroke. Its main trunk (M1 segment) arises from the internal carotid artery and divides into two main divisions (M2 segments) - superior and inferior - within the Sylvian fissure. Some patients have a trifurcation.
Cortical supply (via superficial branches):
- Lateral frontal lobe - motor areas 4 and 6, Broca's area (dominant hemisphere), frontal eye fields
- Parietal lobe - primary sensory cortex, supramarginal and angular gyri
- Superior temporal lobe and insula - Wernicke's area (dominant hemisphere)
Deep supply (via lenticulostriate/penetrating branches):
- Putamen, head and body of caudate nucleus
- Posterior limb of internal capsule
- Outer globus pallidus
- Deep white matter / corona radiata
MCA territory - lateral view showing superior and inferior divisions, Broca's area, Wernicke's area, motor/sensory cortex, and visual radiation (Adams & Victor's Principles of Neurology, 12th Ed.)
Coronal section: MCA deep territory (green) includes the internal capsule, putamen, caudate, and corona radiata (Adams & Victor's, 12th Ed.)
Clinical Syndromes by Territory
MCA Stem (M1) Occlusion - Most Severe
Total M1 occlusion produces a combination of all elements below:
| Feature | Mechanism |
|---|---|
| Contralateral hemiplegia (face + arm + leg) | Posterior limb of internal capsule infarction |
| Contralateral hemianesthesia | Sensory cortex + thalamic radiations |
| Homonymous hemianopia | Lateral geniculate body / optic radiations |
| Ipsilateral head and eye deviation | Damage to frontal eye fields (drives eyes toward lesion) |
| Global aphasia (left hemisphere) | Combined Broca + Wernicke damage |
| Anosognosia + hemineglect (right hemisphere) | Non-dominant parietal involvement |
| Initial drowsiness | Widespread neuronal dysfunction |
Cause: Almost always embolic (Fisher, 1975; Caplan, 1989). Atherosclerotic thrombosis is less common but more prevalent in Asian populations (with diabetes and hypertension as key risk factors).
MCA Branch Occlusions (Partial Syndromes)
| Location | Deficits |
|---|---|
| Left MCA superior division | Right face + arm weakness (UMN type), Broca's (non-fluent) aphasia; may have right arm cortical sensory loss; leg relatively spared |
| Left MCA inferior division | Wernicke's (fluent) aphasia + right visual field deficit; motor findings usually absent; patient may appear confused or psychotic |
| Right MCA superior division | Left face + arm weakness (UMN type), left hemineglect (variable) |
| Right MCA inferior division | Profound left hemineglect, left visual and somatosensory deficits; motor findings often absent or subtle |
| Left MCA deep territory | Right pure motor hemiparesis (UMN); larger infarcts may produce aphasia as well |
| Right MCA deep territory | Left pure motor hemiparesis; larger infarcts may produce hemineglect |
Key clinical pearls:
- Face and arm > leg in MCA strokes (leg spared because ACA territory supplies the leg motor strip)
- Dominant hemisphere (left) occlusion: aphasia is the hallmark language finding
- Non-dominant hemisphere (right) occlusion: neglect, anosognosia, constructional apraxia, dysarthria without aphasia
Deep MCA Infarcts (Striatocapsular)
Infarction of lenticulostriate territory produces larger-than-lacunar but smaller-than-cortical syndromes. The most common pattern: partial hemiparesis + limited Broca-type aphasia (often short-lived) or hemineglect. These are typically embolic (M1 embolus lodges and then moves distally, leaving deep structures infarcted with a patent MCA on imaging).
Etiology
- Embolism (cardiac sources: atrial fibrillation, valvular disease, low EF; or artery-to-artery from ICA plaque) - the dominant cause
- In situ atherosclerosis - more common in Asian, diabetic, hypertensive patients
- Lacunar / small vessel disease - affects only penetrating branches
- Hypercoagulable states - protein C/S deficiency, Factor V Leiden, antiphospholipid syndrome, malignancy, sickle cell
Risk factors: hypertension, diabetes, hypercholesterolemia, smoking, obesity, atrial fibrillation, prior stroke/TIA.
Workup
Immediate:
- Non-contrast head CT - performed within 20 minutes of arrival to exclude hemorrhage before giving thrombolytics
- CT Angiography (CTA) - identifies large vessel occlusion (LVO) at M1/M2
- CT Perfusion or MRI DWI/PWI - identifies ischemic core vs. salvageable penumbra; guides thrombectomy eligibility
- Blood: CBC, BMP, coagulation (PT/INR/aPTT), glucose, type and screen
- ECG (detect AFib), cardiac monitoring, echocardiography (TTE/TEE)
- NIHSS score - standard neurological severity assessment
Diagnostic workup for etiology:
- 24-72 hour cardiac monitoring (paroxysmal AFib)
- Carotid duplex / MRA for ICA stenosis
- Hypercoagulability panel if indicated (young patient, no clear cause)
Acute Management
Reperfusion Therapies
1. IV Alteplase (tPA)
- Indicated within 4.5 hours of symptom onset (earlier = better outcomes)
- Dose: 0.9 mg/kg IV (max 90 mg), 10% as bolus, rest over 60 minutes
- Key contraindications: hemorrhage on CT, BP >185/110 mmHg (uncontrolled), active bleeding, recent major surgery (<2 weeks), platelets <100,000, INR >1.7
- IV tenecteplase has been compared favorably to alteplase and is an emerging alternative
- Time pressure is paramount: "door-to-needle" <30 minutes strongly reduces disability at 3 months
2. Endovascular Mechanical Thrombectomy (MT)
- Indicated for large vessel occlusion (ICA, M1, proximal M2) with significant NIHSS deficits
- Time window: up to 6 hours from onset (selected patients to 24 hours with favorable perfusion imaging)
- MR-CLEAN (2015) and 4 concurrent trials (ESCAPE, SWIFT PRIME, EXTEND-IA, REVASCAT) demonstrated dramatically superior 90-day outcomes - trials terminated early for benefit
- tPA remains the standard first-line therapy even in those who will undergo MT (bridging therapy)
- Advantages over tPA: fewer exclusion criteria, works for large clot burden, effective where tPA achieves <20% recanalization
A 2025 meta-analysis of RCTs (Lin et al., PMID 40245084) confirmed benefit of thrombectomy even in patients with large ischemic cores, expanding the eligible population.
General Supportive Care
- BP management: Permissive hypertension (allow up to 220/120 mmHg pre-thrombolysis; maintain <185/110 for tPA candidates). For those not receiving reperfusion, target systolic <220 mmHg unless hypertensive emergency. Post-thrombectomy or tPA: target <180 mmHg.
- IV fluids: Normal saline (isotonic), no glucose-containing solutions (glucose worsens ischemic injury via osmotic shifts)
- Normovolemia, normothermia, normoglycemia
- Admit to dedicated stroke unit / ICU; frequent neurological checks
- Aspirin 325 mg within 24-48 hours (if no thrombolytics given) for antiplatelet effect
Malignant MCA Syndrome
Large MCA territory infarctions (typically >50% of MCA territory) cause massive cerebral edema, typically peaking at 3-5 days post-stroke. This can cause:
- Midline shift
- Transtentorial herniation
- Death or severe disability
Decompressive hemicraniectomy is a life-saving option in selected patients (younger age, dominant-hemisphere involvement controversial). Studies show favorable mortality reduction, though functional outcome is still poor in many (less than half return home after rehabilitation). Shared decision-making with family regarding quality of life expectations is essential.
Secondary Prevention
| Category | Intervention |
|---|---|
| Non-cardioembolic stroke | Antiplatelet therapy (aspirin, clopidogrel, or aspirin+dipyridamole) |
| Cardioembolic (AFib) | Anticoagulation (DOACs preferred over warfarin) |
| ICA stenosis >70% | Carotid endarterectomy (CEA) or stenting |
| Intracranial atherosclerosis | Aggressive medical management (aspirin, statins, BP control); angioplasty/stenting in refractory cases |
| All patients | Statin therapy, BP control (<130/80), lifestyle modification |
Summary
The MCA supplies the largest portion of the cerebral hemisphere. Its occlusion at different levels produces predictable but variable deficits - from global aphasia + hemiplegia in M1 occlusion, to isolated fluent aphasia with inferior division occlusion, to pure motor deficits with deep territory involvement. Time-sensitive reperfusion with IV tPA and/or mechanical thrombectomy is the cornerstone of acute treatment. Malignant MCA stroke may require hemicraniectomy. Long-term management targets the underlying etiology (AFib, atherosclerosis, hypercoagulability).
Sources: Adams & Victor's Principles of Neurology 12th Ed., Neuroanatomy Through Clinical Cases 3rd Ed., Tintinalli's Emergency Medicine, Schwartz's Principles of Surgery 11th Ed. | PMID 40245084 (2025 meta-analysis, thrombectomy in large ischemic core)
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