Stroke

Stroke – High-Yield Study Guide for Medical Students

Definition

Stroke is a sudden onset of focal (or occasionally global) neurological deficit lasting >24 hours (or causing death) due to a disturbance in cerebral blood flow from either ischemia or hemorrhage. Acute ischemic stroke (AIS) accounts for ~80–85% of cases and results from vascular occlusion, whereas hemorrhagic stroke (intracerebral or subarachnoid hemorrhage) results from rupture of a cerebral vessel.

Epidemiology

Stroke is a leading cause of adult disability and one of the top causes of death worldwide, with substantial socioeconomic burden from mortality, loss of productivity, and long-term care needs. Epidemiologic data from multiple regions show that stroke incidence and case fatality remain high, with significant knowledge gaps about stroke risk factors and warning symptoms even among young adults and university students, underscoring the need for public and professional education.^[1][2]

• Prevalence: Millions of survivors worldwide; prevalence rises sharply with age.
• Type distribution:
  • Ischemic stroke: ~80–85%
  • Intracerebral hemorrhage (ICH): ~10–15%
  • Subarachnoid hemorrhage (SAH): ~5%
• Major modifiable risk factors: Hypertension, atrial fibrillation, diabetes, dyslipidemia, smoking, obesity, physical inactivity, and unhealthy diet.
• Non-modifiable risk factors: Age, male sex (younger ages), family history, race/ethnicity, genetic and congenital vasculopathies.

Pathophysiology

Ischemic Stroke

Ischemic stroke results from reduced cerebral blood flow below the threshold required for neuronal viability, usually due to arterial occlusion. Mechanisms include large-artery atherosclerosis and thrombosis, cardioembolism (e.g., atrial fibrillation), small vessel lipohyalinosis causing lacunar infarcts, and less common causes such as arterial dissection, vasculitis, and hypercoagulable states.^[3]

• Ischemic core: Area of critically reduced blood flow leading to rapid, irreversible cell death.
• Ischemic penumbra: Surrounding region with functionally impaired but structurally viable tissue that is potentially salvageable with timely reperfusion.
• Cellular events:
  • Energy failure from ATP depletion
  • Loss of ionic gradients → cytotoxic edema
  • Excess glutamate release → excitotoxicity
  • Calcium influx → activation of degradative enzymes and free radical injury
  • Inflammatory cascade and breakdown of the blood–brain barrier

Systemic stress response involves activation of the hypothalamic–pituitary–adrenal axis, elevating serum cortisol, which correlates with stroke severity and worse functional outcome in AIS, reflecting the interplay of neuroendocrine stress, metabolic derangement, and inflammation.^[4]

Hemorrhagic Stroke

Intracerebral hemorrhage typically results from rupture of small penetrating arteries due to chronic hypertension or cerebral amyloid angiopathy. Bleeding causes mass effect, increased intracranial pressure, and damage from blood breakdown products. Subarachnoid hemorrhage is most often due to rupture of a saccular (berry) aneurysm, leading to diffuse meningeal irritation and risk of vasospasm.

Clinical Presentation

Stroke classically presents with sudden-onset focal neurological deficits. Symptoms depend on the vascular territory, size of lesion, and whether the process is ischemic or hemorrhagic.

• Common general features:
  • Sudden onset of symptoms (seconds to minutes)
  • Focal neurological deficits corresponding to a vascular territory
  • Negative symptoms (loss of function) more typical than positive phenomena
• Typical symptoms and signs:
  • Unilateral weakness or numbness of face, arm, and/or leg
  • Facial droop
  • Dysarthria or aphasia (expressive, receptive, or global)
  • Visual field deficits (e.g., homonymous hemianopia)
  • Diplopia, vertigo, ataxia, or dysmetria (posterior circulation)
  • Gaze deviation, neglect, or visual–spatial deficits
  • Sudden severe headache (”thunderclap”) more suggestive of SAH
  • Altered level of consciousness, more common in large strokes and hemorrhage

Large registry studies of reperfusion-eligible AIS patients highlight that baseline stroke severity (e.g., higher NIHSS), age, comorbidities, and onset-to-treatment time are closely related to functional outcomes, emphasizing the importance of rapid recognition and assessment of clinical presentation.^[5]

Stroke Syndromes by Vascular Territory

• Middle cerebral artery (MCA):
  • Contralateral weakness and sensory loss (face > arm > leg)
  • Aphasia if dominant hemisphere; neglect and anosognosia if non-dominant
  • Gaze preference toward side of lesion; homonymous hemianopia
• Anterior cerebral artery (ACA):
  • Contralateral leg > arm weakness and sensory loss
  • Abulia, akinetic mutism, urinary incontinence, frontal lobe behavioral changes
• Posterior cerebral artery (PCA):
  • Contralateral homonymous hemianopia
  • Alexia without agraphia (dominant occipital involvement)
  • Thalamic syndromes (sensory loss, pain) if thalamus involved
• Vertebrobasilar/posterior circulation:
  • Vertigo, ataxia, nystagmus
  • Dysphagia, dysarthria
  • Crossed signs: ipsilateral cranial nerve deficits with contralateral motor/sensory deficits
  • Locked-in syndrome with pontine lesions
• Lacunar strokes (small vessel):
  • Pure motor hemiparesis
  • Pure sensory stroke
  • Ataxic hemiparesis
  • Dysarthria–clumsy hand syndrome

Diagnosis

Stroke diagnosis is primarily clinical, supported by neuroimaging and vascular studies. Time of last known well is critical for therapeutic decisions, particularly reperfusion eligibility.

Initial Assessment

• Rapid ABC stabilization and assessment of vital signs.
• Determine onset time (or last known well), stroke risk factors, current medications (especially anticoagulants/antiplatelets), and comorbidities.
• Focused neurological examination including NIH Stroke Scale (NIHSS) to quantify severity.
• Point-of-care glucose to exclude hypoglycemia as a mimic.

Neuroimaging

• Non-contrast CT (NCCT):
  • First-line imaging to rapidly exclude intracranial hemorrhage.
  • May be normal early in AIS; early signs include loss of grey–white differentiation, sulcal effacement, and hyperdense vessel sign.
• CT angiography (CTA):
  • Assesses intracranial and extracranial vessels for large vessel occlusion (LVO), stenosis, and dissection.
  • Useful to triage patients for mechanical thrombectomy.
• CT perfusion (CTP) or MR perfusion:
  • Demonstrates ischemic core vs penumbra; widely used in extended window thrombolysis and thrombectomy selection.
• MRI brain with DWI/FLAIR:
  • Highly sensitive for acute infarction; DWI/FLAIR mismatch can identify patients with unknown onset who may benefit from reperfusion.

Recent systematic review and meta-analysis of intravenous alteplase administered beyond the conventional 4.5-hour window emphasizes that imaging-based selection (e.g., perfusion, core/penumbra mismatch) is central to safely extending thrombolysis to selected patients by identifying viable tissue at risk rather than relying solely on time from onset.^[6][7]

Laboratory Evaluation

• Basic labs: CBC, electrolytes, renal function, glucose, coagulation profile (PT/INR, aPTT), lipid profile, HbA1c.
• Cardiac markers and ECG to screen for myocardial ischemia and atrial fibrillation.
• Toxicology and pregnancy testing when indicated.
• Targeted hypercoagulable workup in cryptogenic stroke or young patients without clear etiology (e.g., antiphospholipid antibodies, thrombophilia panels), guided by clinical context and timing, as indiscriminate testing can yield low diagnostic yield and false positives.^[3]

Vascular and Cardiac Workup

• Carotid duplex ultrasound or CTA/MRA neck for extracranial carotid disease.
• Transthoracic or transesophageal echocardiography for cardioembolic sources (e.g., atrial thrombus, PFO, valvular lesions).
• Prolonged cardiac monitoring for paroxysmal atrial fibrillation in cryptogenic stroke.

Management

Stroke management includes hyperacute reperfusion therapies, acute supportive care, secondary prevention, and rehabilitation. Timely recognition and organized systems of care significantly improve outcomes, as demonstrated in large reperfusion registries where onset-to-treatment times and recanalization strategies are major determinants of functional recovery.^[5]

Initial Stabilization

• Ensure airway protection; consider intubation if impaired consciousness or inability to protect airway.
• Maintain oxygen saturation >94% and avoid routine supplemental oxygen if not hypoxic.
• Manage blood pressure according to stroke type and treatment plans (permissive hypertension in AIS not receiving thrombolysis; stricter control for hemorrhagic stroke or before/after reperfusion as per guideline thresholds).
• Correct hypoglycemia and avoid hyperglycemia; treat fever aggressively.
• Head of bed at ~30 degrees to reduce aspiration risk while balancing cerebral perfusion.

Reperfusion Therapy in Acute Ischemic Stroke

Intravenous Thrombolysis (IVT)

IV alteplase (rt-PA) has been the standard pharmacologic reperfusion therapy within 4.5 hours of symptom onset in eligible AIS patients. Standard dosing is 0.9 mg/kg (maximum 90 mg) with 10% as bolus over 1 minute and the remainder over 60 minutes. The decision to administer IVT is based on clinical deficits, time from onset, imaging to exclude hemorrhage, and absence of major contraindications (e.g., recent intracranial hemorrhage, uncontrolled hypertension, active bleeding).

Evidence increasingly supports imaging-based selection to extend thrombolysis beyond 4.5 hours in carefully selected patients using modalities like CT/MR perfusion and DWI/FLAIR mismatch to identify salvageable tissue, with systematic review and meta-analysis data evaluating efficacy and safety of alteplase in the extended time window.^[6][7]

Endovascular Therapy (Mechanical Thrombectomy)

• Indicated for anterior circulation large vessel occlusions (ICA, proximal MCA) in patients with significant neurological deficit, within specific time windows (generally up to 6 hours, and up to 24 hours in selected cases based on imaging).
• Performed via catheter-based retrieval or aspiration of thrombus; can be used with or without IVT depending on eligibility and timing.
• Registry data show that successful reperfusion and shorter onset-to-groin puncture times are associated with improved functional outcomes.^[5]

Management of Hemorrhagic Stroke

• Intracerebral hemorrhage:
  • Rapid blood pressure lowering to guideline targets (e.g., systolic <140 mmHg in many patients) if no contraindications.
  • Reversal of anticoagulation (vitamin K, PCC for warfarin; specific reversal agents for DOACs as available).
  • Management of increased intracranial pressure: head elevation, hyperosmolar therapy, neurosurgical evaluation for selected cases (e.g., large cerebellar hemorrhage).
• Subarachnoid hemorrhage (aneurysmal):
  • Secure aneurysm via surgical clipping or endovascular coiling.
  • Prevent vasospasm (e.g., nimodipine) and manage hydrocephalus (e.g., external ventricular drain).

Secondary Prevention

• Antithrombotic therapy:
  • Antiplatelets (e.g., aspirin, clopidogrel, or short-term dual antiplatelet therapy in specific minor stroke/TIA scenarios).
  • Oral anticoagulation for cardioembolic stroke from atrial fibrillation (warfarin or DOACs) after appropriate timing post-stroke.
• Risk factor control:
  • Blood pressure control (typically <130/80 mmHg where tolerated).
  • High-intensity statin therapy and lipid optimization.
  • Glycemic control in diabetes.
  • Smoking cessation and limitation of alcohol.
  • Dietary modification (e.g., Mediterranean-style diet) and regular physical activity.
• Carotid revascularization:
  • Carotid endarterectomy or stenting in selected patients with symptomatic high-grade carotid stenosis.

Rehabilitation and Long-Term Care

• Early mobilization and multidisciplinary rehabilitation (physiotherapy, occupational therapy, speech and language therapy) to improve functional recovery.
• Focused management of spasticity, contractures, swallowing dysfunction, communication deficits, and cognitive/behavioral changes.
• Assessment of driving, occupational capacity, and psychosocial support for patient and caregivers.

Key Clinical Pearls for Exams and Practice

• Time is brain: Neurons die rapidly during ischemia; every minute of untreated large vessel stroke leads to an enormous loss of neurons, so rapid triage and imaging are critical.
• Differentiate ischemic vs hemorrhagic stroke with urgent non-contrast CT before initiating thrombolysis.
• Last known well time is the anchor for reperfusion eligibility; if onset is unwitnessed (e.g., wake-up stroke), imaging-based criteria (DWI/FLAIR or perfusion) may guide treatment selection.
• Consider stroke mimics such as seizures with post-ictal deficits, hypoglycemia, migraine with aura, functional neurological disorders, and toxic-metabolic encephalopathies, but prioritize rapid imaging when stroke is suspected.
• Use stroke scales such as NIHSS to quantify severity and monitor progress; higher baseline NIHSS correlates with worse outcomes and is often used in reperfusion decisions and registries.^[5]
• Hypercoagulable testing should be targeted, especially in younger patients with cryptogenic stroke or when clinical features suggest an underlying thrombophilia; indiscriminate testing can be low-yield and misleading.^[3]
• Extended-window thrombolysis and thrombectomy rely more on tissue-based (imaging) than purely time-based criteria; understanding perfusion imaging and core–penumbra concepts is increasingly critical for modern stroke care.^[6][7]
• Neuroendocrine response (e.g., elevated cortisol) is associated with greater stroke severity and poorer outcomes, reflecting the interaction between brain injury, systemic stress, metabolic dysregulation, and inflammation.^[4]
• Public and professional education on stroke warning signs (e.g., FAST: Face drooping, Arm weakness, Speech difficulty, Time to call emergency services) remains suboptimal even among university students, reinforcing the role of medical students and clinicians as educators.^[1][2]

Summary

Stroke is a common, time-critical neurologic emergency with high morbidity and mortality. For medical students, mastery of stroke syndromes, rapid diagnostic pathways, and current reperfusion and secondary prevention strategies is essential. Contemporary practice increasingly uses imaging-based selection for reperfusion beyond traditional time windows, and large registry and observational data continue to refine risk stratification, hypercoagulable evaluation, and prognostic markers like cortisol and advanced imaging patterns in acute ischemic stroke.^[6][4][5]