Stroke - Comprehensive Exam Review

1. Definition & Epidemiology

2. Classification

3. Pathophysiology of Ischemic Stroke

1. Embolism - a thrombus from the heart (AF, mural thrombus, valve disease) or from an atherosclerotic plaque (carotid bifurcation, aortic arch) travels distally and occludes an intracranial vessel.
2. In situ thrombosis - typically affects small penetrating arteries, producing lacunar infarcts in the basal ganglia, thalamus, internal capsule, and pons.
3. Hypoperfusion - flow-limiting stenosis of a major extracranial vessel (e.g., internal carotid) produces "watershed" ischemia between arterial territories.

4. Etiology of Ischemic Stroke - High-Yield Table

5. Risk Factors

6. Clinical Features by Vessel Territory

Anterior Circulation (ICA/MCA/ACA)

• Contralateral face and arm > leg weakness and sensory loss (arm-face predominance)
• Dysphasia/aphasia (dominant hemisphere - usually left): Broca's = non-fluent; Wernicke's = fluent, incomprehensible
• Neglect, anosognosia, constructional apraxia (non-dominant hemisphere)
• Contralateral homonymous hemianopia
• Ipsilateral gaze deviation ("eyes look toward the lesion")
• Limb ataxia if large

• Contralateral leg > arm weakness/sensory loss (leg predominance, reversed from MCA)
• Urinary incontinence
• Abulia, kinetic mutism (bilateral ACA occlusion)
• Contralateral grasp reflex

• Amaurosis fugax (monocular visual loss) - ischemia of ipsilateral retina via ophthalmic artery
• If circle of Willis is competent, may be asymptomatic
• Massive infarction (MCA + ACA territories) if circle of Willis is incompetent

Posterior Circulation (Vertebrobasilar)

• Ipsilateral: facial pain/temp loss, Horner's, dysarthria, dysphagia, ataxia
• Contralateral: limb/trunk pain/temp loss (spinothalamic)
• Preserved motor power (corticospinal tract spared)
• Vertigo, nausea, hiccups

• Bilateral pontine signs, "locked-in" syndrome
• High mortality if complete

• Contralateral homonymous hemianopia with macular sparing
• Alexia without agraphia (dominant hemisphere)
• Thalamic sensory loss

7. Lacunar Syndromes (Small Vessel Disease)

8. Transient Ischemic Attack (TIA)

ABCD² Score (risk of stroke after TIA)

• Score 0-3 = Low risk (1% stroke at 48h)
• Score 4-5 = Moderate risk (4.1% at 48h)
• Score ≥6 = High risk (8% at 48h; 22% at 3 months for score 7)

9. Diagnosis & Imaging

Noncontrast Head CT - First-line in Acute Stroke

• Primary role: Exclude hemorrhage before thrombolysis
• Findings in ischemic stroke: Hyperdense MCA sign (acute clot), loss of gray-white differentiation, subtle edema; frank hypodensity appears in 6-24h
• Findings in hemorrhagic stroke: Hyperdensity (bright white) of blood immediately

CT Angiography (CTA)

• Images entire arterial system from arch to vertex in one study
• Identifies large vessel occlusion (LVO) amenable to thrombectomy

CT Perfusion (CTP)

• Distinguishes infarct core (irreversibly damaged) from ischemic penumbra (salvageable)
• Critical for selecting thrombectomy candidates in the 6-24h window (DAWN/DEFUSE-3 trials)

MRI

• DWI (diffusion-weighted imaging): shows infarction within minutes of onset - most sensitive early
• FLAIR: shows infarction from days to years
• MRA: detects vessel stenosis/occlusion
• Superior to CT for posterior fossa infarcts (CT has poor sensitivity there)

10. Acute Management of Ischemic Stroke

Step-by-Step Pathway

IV Thrombolysis (tPA / Alteplase)

• Dose: 0.9 mg/kg IV (max 90 mg); 10% as bolus, rest over 60 min
• Window: Within 4.5 hours of symptom onset (or last seen well time)
• Alternative agent: Tenecteplase (single IV bolus) is now preferred at many centers for its convenience
• Contraindications to IV tPA:
  • Hemorrhage on CT
  • Prior stroke or head trauma in last 3 months
  • Major surgery within 14 days
  • Active internal bleeding
  • BP >185/110 (must treat first)
  • Platelet count <100,000; INR >1.7
  • Blood glucose <50 or >400 mg/dL
  • Improving symptoms (TIA) - relative contraindication

Mechanical Thrombectomy (Endovascular)

• Indication: Large vessel occlusion (ICA terminus, M1/M2 MCA, basilar artery)
• Window: Within 24 hours of onset, if favorable perfusion imaging (selected by CTP/MR perfusion)
• Patients in the 0-6h window can get both IV tPA + thrombectomy ("bridging")
• Patients in 6-24h window: thrombectomy only (no IV tPA); selection based on perfusion mismatch (DAWN/DEFUSE-3 criteria)
• Source: Harrison's 22E, Bradley's Neurology in Clinical Practice

Blood Pressure Management in Acute Ischemic Stroke

• If giving IV tPA: Target BP <185/110 before and maintain <180/105 during infusion
• If NOT giving tPA: Permissive hypertension - treat only if BP >220/120 (collateral flow depends on elevated BP)
• Long-term: Target systolic <120 mmHg

Antiplatelet Therapy (Ischemic Stroke)

• Aspirin 325 mg should be started within 24-48h of stroke onset (not within 24h of tPA)
• Dual antiplatelet (aspirin + clopidogrel) for 21 days after minor stroke/high-risk TIA (POINT + CHANCE trials)
• Reduces early recurrence; major hemorrhage risk increased (0.2% → 0.9%)

Anticoagulation

• Atrial fibrillation: Start oral anticoagulation (apixaban preferred); timing depends on infarct size
• NOT recommended for routine atherothrombotic stroke (no benefit over aspirin; increased hemorrhage)
• May be used for dural sinus thrombosis, arterial dissection (limited evidence)

11. Hemorrhagic Stroke

Intracerebral Hemorrhage (ICH)

• Sudden onset of focal deficit + severe headache + elevated BP
• Progressive worsening over minutes to hours (unlike embolic = maximal at onset)
• Signs of raised ICP: vomiting, decreased consciousness, Cushing's response

1. Putamen (55%)
2. Thalamus (20%)
3. Pons (10%)
4. Cerebellum (10%)
5. Lobar (5% - more often amyloid angiopathy)

• Reverse anticoagulation urgently (vitamin K + PCC for warfarin; idarucizumab for dabigatran; andexanet alfa for factor Xa inhibitors)
• Target BP ≤140/90 mmHg (INTERACT2, ATACH-II trials)
• No routine corticosteroids (do NOT use for cerebral edema in ICH)
• Surgical evacuation: cerebellum >3cm; superficial lobar; herniation
• ICP monitoring if GCS ≤8; osmotherapy (mannitol) for raised ICP

Subarachnoid Hemorrhage (SAH)

• "Thunderclap headache" - worst headache of life, sudden onset
• Meningism (neck stiffness, photophobia)
• +/- third nerve palsy (posterior communicating artery aneurysm)

• CT head (sensitive 98% within 12h, decreases after)
• If CT negative + clinical suspicion: Lumbar puncture for xanthochromia (yellow CSF) - gold standard if CT negative
• CTA or DSA angiography to identify aneurysm

• Rebleeding (highest risk first 24h; ~20% in 2 weeks)
• Vasospasm (days 3-14; treat with nimodipine, triple-H therapy historically)
• Hydrocephalus
• Hyponatremia (SIADH or cerebral salt wasting)

• Nimodipine 60 mg q4h for 21 days (reduces vasospasm and improves neurological outcome)
• Surgical clipping or endovascular coiling of aneurysm

12. Secondary Prevention

13. Rehabilitation

• Stroke unit care reduces mortality and improves neurological outcomes significantly
• Early physical, occupational, and speech therapy
• Prevent complications: pneumonia (pneumatic compression/early mobilization), DVT (pneumatic compression stockings), pressure sores, contractures
• Constrained movement therapy (immobilizing the unaffected side) improves hemiparesis even years post-stroke - evidence for neural plasticity
• Selective serotonin reuptake inhibitors (SSRIs) may help post-stroke depression; motor benefit controversial
• Source: Harrison's 22E

14. High-Yield Exam Points

• FAST acronym: Face drooping, Arm weakness, Speech difficulty, Time to call emergency services
• "Time is brain": 1.9 million neurons lost per minute
• First investigation: Non-contrast CT head (to exclude hemorrhage)
• IV tPA window: 4.5 hours; dose 0.9 mg/kg
• Thrombectomy window: Up to 24 hours if perfusion imaging favourable
• Do not give tPA if: hemorrhage on CT, BP >185/110 (treat first), INR >1.7, or symptoms are improving
• Lacunar infarcts = small vessel; hypertension; pure motor/pure sensory most common
• Wallenberg = lateral medulla = PICA = crossed deficits, Horner's, dysphagia, no motor loss
• PCA = homonymous hemianopia with macular sparing
• ICH #1 cause = hypertension; #1 site = putamen
• SAH = worst headache of life; xanthochromia on LP; nimodipine prevents vasospasm
• TIA management = dual antiplatelet (aspirin + clopidogrel) × 21 days
• AF-related stroke = anticoagulation (DOAC first line)
• No heparin for routine atherothrombotic stroke