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Stroke — overview

TL;DR — Stroke is acute brain injury from infarction or hemorrhage and remains a top global cause of death and disability: 12.2 million incident events and 6.55 million deaths were estimated in 2019 (GBD 2019 Stroke Collaborators 2021, PMID 34487721). Treatment is time- and mechanism-dependent: rapid imaging separates ischemia from hemorrhage; alteplase and tenecteplase are thrombolytic options, and endovascular thrombectomy has transformed large-vessel-occlusion care (NINDS 1995, PMID 7477192; Menon 2022, PMID 35779553; Goyal 2016, PMID 26898852). Selected patients benefit from thrombectomy as late as 24 hours when clinical–imaging mismatch indicates viable tissue (Nogueira 2018, PMID 29129157; Albers 2018, PMID 29364767). Organized stroke-unit care, rehabilitation, and cause-specific secondary prevention are as important as reperfusion (Langhorne 2020, PMID 32324916; Kleindorfer 2021, PMID 34024117). The central unresolved problems are equitable access, treatment of large established infarcts and hemorrhage, and biologically targeted recovery.

Definition and diagnostic anchors

  • Stroke is a clinical syndrome of sudden focal neurological dysfunction attributable to cerebral, spinal, or retinal infarction or to non-traumatic intracranial hemorrhage.
  • The first branching decision is ischemic versus hemorrhagic stroke, established by urgent non-contrast CT or MRI; vascular imaging then identifies large-vessel occlusion and perfusion imaging can estimate core and salvageable tissue.
  • A transient ischemic attack is transient neurological dysfunction caused by focal ischemia without acute infarction; it is a warning phenotype, not a benign diagnosis.
  • Ischemic mechanisms include large-artery atherosclerosis, cardioembolism, small-vessel occlusion, other determined causes, and cryptogenic/undetermined stroke; cerebral small-vessel disease is itself a heterogeneous arteriolar disorder linked to lacunes, white-matter lesions, microbleeds, gait and cognitive decline (Wardlaw 2019, PMID 31097385; Chojdak-Łukasiewicz 2021, PMID 33768739).
  • Intracerebral hemorrhage requires immediate attention to anticoagulant reversal, blood pressure, hydrocephalus, mass effect and neurosurgical indications (Greenberg 2022, PMID 35579034).

Headline epidemiology

2019 global estimate Value Source
Incident strokes 12.2 million (GBD 2019 Stroke Collaborators 2021, PMID 34487721)
People living after stroke 101 million (GBD 2019 Stroke Collaborators 2021, PMID 34487721)
Stroke deaths 6.55 million (GBD 2019 Stroke Collaborators 2021, PMID 34487721)
Stroke DALYs 143 million (GBD 2019 Stroke Collaborators 2021, PMID 34487721)
Deaths in low- and lower-middle-income countries 86% (GBD 2019 Stroke Collaborators 2021, PMID 34487721)
  • Age-standardized rates declined globally from 1990 to 2019, but absolute counts rose with population growth and aging (GBD 2019 Stroke Collaborators 2021, PMID 34487721).
  • High systolic blood pressure is the dominant modifiable population risk; smoking, high body-mass index, high fasting glucose, ambient particulate pollution, and diet contribute substantially (GBD 2019 Stroke Collaborators 2021, PMID 34487721).
  • Premature stroke creates distinct diagnostic and lifetime-burden problems; contemporary reviews emphasize increasing exposure to conventional vascular risks alongside uncommon arteriopathies and thrombophilias (Potter 2022, PMID 36374365).

Mechanism sketch

Ischemia

Arterial occlusion abruptly reduces blood flow. The irreversibly injured core expands into electrically silent but potentially viable penumbra according to collateral supply, metabolic demand, temperature, glucose and time. This biology explains why treatment effect decays with delay and why imaging can identify late-window patients whose tissue clock is slower than their wall clock (Emberson 2014, PMID 25106063; Nogueira 2018, PMID 29129157; Albers 2018, PMID 29364767).

Reperfusion can rescue penumbra but may also produce edema, hemorrhagic transformation and inflammatory injury. Decades of neuroprotection trials have not produced an adjunct with the effect size and reproducibility of reperfusion, despite extensive preclinical candidates (Paul 2021, PMID 33144066).

Hemorrhage

In intracerebral hemorrhage, primary mechanical tissue disruption is followed by hematoma expansion, perihematomal edema, inflammatory toxicity, intraventricular extension and raised intracranial pressure. Rapid blood-pressure lowering in INTERACT2 was safe and improved ordinal functional outcome, although it did not significantly reduce the primary dichotomous endpoint (Anderson 2013, PMID 23713578); the 2022 AHA/ASA guideline places this evidence within broader reversal and surgical pathways (Greenberg 2022, PMID 35579034).

Acute treatment landscape

Intravenous thrombolysis

  • The NINDS trial established intravenous alteplase within 3 hours despite increased symptomatic intracranial hemorrhage, with more patients having minimal or no disability at 3 months (NINDS 1995, PMID 7477192).
  • ECASS III extended evidence to 3–4.5 hours in selected patients (Hacke 2008, PMID 18815396).
  • Individual-patient meta-analysis showed benefit falls continuously with treatment delay: speed remains critical even within an authorized window (Emberson 2014, PMID 25106063; Lees 2010, PMID 20472172).
  • The pragmatic Canadian AcT trial found tenecteplase non-inferior to alteplase, supporting a simpler single-bolus alternative in eligible acute ischemic stroke (Menon 2022, PMID 35779553).

Mechanical thrombectomy

  • MR CLEAN was the first positive modern randomized trial of intra-arterial treatment for proximal anterior-circulation occlusion (Berkhemer 2015, PMID 25517348).
  • HERMES individual-patient meta-analysis across five trials found a common odds ratio of 2.49 for reduced disability; benefit extended across prespecified subgroups, with treatment speed remaining decisive (Goyal 2016, PMID 26898852).
  • DAWN selected patients 6–24 hours after last known well using a clinical-core mismatch; DEFUSE 3 selected 6–16 hours using perfusion mismatch, establishing late-window thrombectomy for tissue-selected patients (Nogueira 2018, PMID 29129157; Albers 2018, PMID 29364767).

Organized care and rehabilitation

Stroke-unit care reduces death or dependency compared with alternative inpatient models and should not be treated as a logistical extra (Langhorne 2020, PMID 32324916). Rehabilitation begins with prevention of complications, swallowing and mobility assessment, then task-specific motor, language, cognitive and participation work; the 2026 AHA/ASA adult rehabilitation guideline replaces its 2016 predecessor (Richards 2026, PMID 42657476; Winstein 2016, PMID 27145936). Recovery research still lacks uniform time points and biomarkers, motivating consensus definitions from the Stroke Recovery and Rehabilitation Roundtable (Bernhardt 2017, PMID 28697708).

Secondary prevention

  • A perindopril-based blood-pressure regimen reduced recurrent stroke in 6,105 people with prior stroke or TIA in PROGRESS (PROGRESS Collaborative Group 2001, PMID 11589932).
  • Short-course dual antiplatelet therapy after minor non-cardioembolic stroke or high-risk TIA reduces early ischemic recurrence but increases bleeding with longer exposure; CHANCE and POINT define the evidence boundary (Wang 2013, PMID 23803136; Johnston 2018, PMID 29766750; Pan 2019, PMID 31424481).
  • For atrial fibrillation, anticoagulation rather than antiplatelet therapy addresses cardioembolic risk; apixaban was superior to warfarin for stroke/systemic embolism with less bleeding in ARISTOTLE (Granger 2011, PMID 21870978).
  • Symptomatic carotid stenosis can warrant endarterectomy, with benefit strongly dependent on stenosis severity, timing and operative risk (ECST 1998, PMID 9593407).
  • Patent-foramen-ovale closure is appropriate only in selected younger patients after exclusion of competing causes; DEFENSE-PFO focused on high-risk anatomical features (Lee 2018, PMID 29544871).
  • The 2021 AHA/ASA guideline integrates risk-factor control and mechanism-specific antithrombotic and procedural choices (Kleindorfer 2021, PMID 34024117).

Research frontier

  • Extending thrombectomy to larger cores, distal/medium vessels and resource-limited systems while preserving net benefit.
  • Making tenecteplase selection and dosing uniform across pre-thrombectomy and non-thrombectomy populations (Menon 2022, PMID 35779553).
  • Preventing hematoma expansion and improving functional outcome after ICH, where blood-pressure treatment has a smaller effect than reperfusion has in ischemia (Anderson 2013, PMID 23713578; Greenberg 2022, PMID 35579034).
  • Developing valid recovery biomarkers and treatment-dose standards that transfer across trials (Bernhardt 2017, PMID 28697708).
  • Closing the disproportionate mortality and access burden in lower-income settings (GBD 2019 Stroke Collaborators 2021, PMID 34487721).

One condition, several distinct treatment logics

Problem Immediate biological target Dominant evidence strategy Main residual gap
Arterial occlusion Restore macrovascular and tissue flow Thrombolysis/thrombectomy RCTs Distal occlusion, large core, no-reflow
Intracerebral hemorrhage Limit expansion and secondary injury BP, reversal, surgery, care-bundle trials Large functional effect remains elusive
Aneurysmal SAH Prevent rebleeding and delayed ischemia Aneurysm occlusion and complication prevention Early brain injury and individualized DCI prevention
Recurrent ischemia Treat causal vascular mechanism Risk-factor and mechanism-specific trials Competing causes and adherence
Disability Drive restitution, compensation, and participation Rehabilitation trials and organized care Dose, timing, phenotyping, long-term support

This separation matters because an intervention beneficial for one branch can be harmful in another: anticoagulation prevents AF-related ischemia but worsens active bleeding; higher perfusion pressure may support collateral ischemic flow but aggravate hematoma expansion. Urgent imaging is therefore not merely confirmatory—it determines the initial therapeutic logic (Greenberg 2022, PMID 35579034; Sacco 2013, PMID 23652265).

Burden beyond the 90-day endpoint

The global counts capture death and disability but incompletely represent aphasia, fatigue, cognition, mood, work loss, caregiver health, and participation. In a systematic review of long-term surveys, an average 73.8% of stroke survivors reported at least one unmet need, with wide between-study variation (Chen 2019, PMID 31110106). Organized stroke-unit care produces durable survival and independence benefit—poor-outcome OR 0.77 (95% CI 0.69–0.87)—yet support frequently contracts after discharge (Langhorne 2020, PMID 32324916).

Layer of outcome Typical measure What can remain hidden
Neurological impairment NIHSS Cognition, fatigue, participation, posterior deficits
Global disability mRS Which activity or role is lost
Basic daily function Barthel Index Complex domestic, social, and vocational tasks
Health utility EQ-5D/utility-weighted mRS Communication and caregiver spillover
Social recovery Return to work/home/roles Sustainability and accommodations

This is why outcomes and prognostication, rehabilitation and recovery, and patient experience and advocacy are separate canonical pages rather than an afterthought to acute treatment.

Equity as an effect modifier

In 2019, age-standardized stroke mortality and DALY rates were respectively 3.6 and 3.7 times higher in low-income than high-income countries (GBD 2019 Stroke Collaborators 2021, PMID 34487721). Access determines whether trial efficacy can become population effectiveness: recognition, transport, imaging, thrombolytic availability, thrombectomy transfer, stroke-unit beds, rehabilitation, medication affordability, and surveillance all lie on the causal path (Pandian 2017, PMID 28848165).

The evidence base itself is uneven. Highly selected imaging-rich trials answer whether an intervention can work in eligible participants; implementation studies must establish how selection and delivery perform where scanners, specialists, transport, and follow-up differ.

Open questions

  • How far can thrombectomy eligibility expand beyond the mismatch-selected DAWN/DEFUSE-3 populations without unacceptable hemorrhage or futile reperfusion? (Nogueira 2018, PMID 29129157; Albers 2018, PMID 29364767)
  • Which adjunct can protect brain tissue while reperfusion is arranged, given repeated translational failure of neuroprotection? (Paul 2021, PMID 33144066)
  • What combination of hemostasis, blood-pressure control and surgery materially improves disability after ICH rather than only intermediate endpoints? (Anderson 2013, PMID 23713578; Greenberg 2022, PMID 35579034)
  • Can standardized biological and behavioral measures predict individual recovery well enough to allocate rehabilitation dose? (Bernhardt 2017, PMID 28697708)
  • Which system redesign most reduces the 86% concentration of stroke deaths in lower-income countries? (GBD 2019 Stroke Collaborators 2021, PMID 34487721)

References

  1. GBD 2019 Stroke Collaborators. Global, regional, and national burden of stroke and its risk factors, 1990–2019. Lancet Neurol. 2021. PMID 34487721
  2. National Institute of Neurological Disorders and Stroke rt-PA Stroke Study Group. Tissue plasminogen activator for acute ischemic stroke. N Engl J Med. 1995. PMID 7477192
  3. Emberson J, et al. Effect of treatment delay, age, and stroke severity on intravenous alteplase outcomes. Lancet. 2014. PMID 25106063
  4. Hacke W, et al. Thrombolysis with alteplase 3 to 4.5 hours after acute ischemic stroke. N Engl J Med. 2008. PMID 18815396
  5. Lees KR, et al. Time to treatment with intravenous alteplase and outcome in stroke. Lancet. 2010. PMID 20472172
  6. Menon BK, et al. Intravenous tenecteplase compared with alteplase for acute ischaemic stroke in Canada. Lancet. 2022. PMID 35779553
  7. Berkhemer OA, et al. A randomized trial of intraarterial treatment for acute ischemic stroke. N Engl J Med. 2015. PMID 25517348
  8. Goyal M, et al. Endovascular thrombectomy after large-vessel ischaemic stroke. Lancet. 2016. PMID 26898852
  9. Nogueira RG, et al. Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct. N Engl J Med. 2018. PMID 29129157
  10. Albers GW, et al. Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging. N Engl J Med. 2018. PMID 29364767
  11. Langhorne P, et al. Organised inpatient (stroke unit) care for stroke. Cochrane Database Syst Rev. 2020. PMID 32324916
  12. Greenberg SM, et al. 2022 guideline for spontaneous intracerebral hemorrhage. Stroke. 2022. PMID 35579034
  13. Anderson CS, et al. Rapid blood-pressure lowering in acute intracerebral hemorrhage. N Engl J Med. 2013. PMID 23713578
  14. Kleindorfer DO, et al. 2021 guideline for prevention of stroke after stroke or TIA. Stroke. 2021. PMID 34024117
  15. PROGRESS Collaborative Group. Perindopril-based blood-pressure lowering after stroke or TIA. Lancet. 2001. PMID 11589932
  16. Wang Y, et al. Clopidogrel with aspirin in acute minor stroke or transient ischemic attack. N Engl J Med. 2013. PMID 23803136
  17. Johnston SC, et al. Clopidogrel and aspirin in acute ischemic stroke and high-risk TIA. N Engl J Med. 2018. PMID 29766750
  18. Pan Y, et al. Pooled CHANCE and POINT analysis. JAMA Neurol. 2019. PMID 31424481
  19. Granger CB, et al. Apixaban versus warfarin in patients with atrial fibrillation. N Engl J Med. 2011. PMID 21870978
  20. European Carotid Surgery Trialists. Randomised trial of endarterectomy for recently symptomatic carotid stenosis. Lancet. 1998. PMID 9593407
  21. Lee PH, et al. Cryptogenic stroke and high-risk patent foramen ovale: DEFENSE-PFO. J Am Coll Cardiol. 2018. PMID 29544871
  22. Winstein CJ, et al. Guidelines for adult stroke rehabilitation and recovery. Stroke. 2016. PMID 27145936 22a. Richards LG, et al. 2026 Guideline for Adult Stroke Rehabilitation and Recovery. Stroke. 2026. PMID 42657476
  23. Bernhardt J, et al. Agreed definitions and standards in stroke recovery research. Int J Stroke. 2017. PMID 28697708
  24. Wardlaw JM, et al. Small vessel disease: mechanisms and clinical implications. Lancet Neurol. 2019. PMID 31097385
  25. Chojdak-Łukasiewicz J, et al. Cerebral small vessel disease: a review. Adv Clin Exp Med. 2021. PMID 33768739
  26. Paul S, et al. Emerging neuroprotective strategies for ischemic stroke. Brain Sci. 2021. PMID 33144066
  27. Potter TBH, et al. Epidemiology, risk factors, etiology and outcomes of premature stroke. Curr Atheroscler Rep. 2022. PMID 36374365
  28. Sacco RL, et al. An updated definition of stroke for the 21st century. Stroke. 2013. PMID 23652265
  29. Chen T, et al. Long-term unmet needs after stroke: systematic review. BMJ Open. 2019. PMID 31110106
  30. Pandian JD, et al. Strategies to improve stroke care services in low- and middle-income countries. Neuroepidemiology. 2017. PMID 28848165