Transient Ischaemic Attack (TIA)

1. Clinical Overview

Summary

A Transient Ischaemic Attack (TIA) is a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without acute infarction. [1] Historically defined by the 24-hour rule (symptoms resolving within 24 hours), the modern tissue-based definition emphasizes that the absence of infarction on imaging (specifically diffusion-weighted MRI) distinguishes TIA from stroke, regardless of symptom duration. [2]

TIA represents a medical emergency and a critical warning sign of impending ischaemic stroke. The risk of stroke following TIA is highest in the first 48-72 hours, with early risk ranging from 5-10% within 7 days and 10-20% within 90 days without treatment. [3,4] Urgent assessment, imaging, risk stratification, and initiation of secondary prevention measures can reduce this risk by up to 80%. [5]

The EXPRESS study demonstrated that immediate initiation of treatment (within 24 hours) reduced 90-day stroke risk from 10.3% to 2.1%, establishing the paradigm of TIA as a "stroke emergency" requiring same-day assessment and treatment. [6]

Key Clinical Facts

• Definition Evolution: The shift from time-based (24 hours) to tissue-based definition reflects that most true TIAs resolve within 60 minutes, and symptoms lasting > 1 hour frequently show DWI positivity (indicating infarction). [2]

• Amaurosis Fugax: A TIA affecting the retinal circulation, characterized by painless monocular vision loss described as a "curtain descending" over one eye. This indicates ipsilateral carotid artery disease. [7]

• Crescendo TIA: Two or more TIAs within a short period (typically within one week), representing an unstable cerebrovascular state with very high stroke risk requiring immediate hospital admission. [8]

• ABCD2 Score: A clinical risk stratification tool (Age, Blood pressure, Clinical features, Duration, Diabetes) historically used for triage. However, current NICE guidance recommends all suspected TIAs should be assessed within 24 hours regardless of score, with aspirin 300mg initiated immediately. [1]

• Driving Regulations: In the UK, patients must not drive for 1 month following TIA (DVLA Group 1 licence). Group 2 (HGV/bus) licence holders must stop driving for 1 year and inform DVLA. [9]

Clinical Pearls

Negative vs Positive Symptoms: TIA causes negative symptoms (loss of function: weakness, numbness, vision loss, dysphasia). Positive symptoms (tingling, flashing lights, jerking movements) suggest alternative diagnoses such as migraine with aura or focal seizures.

Carotid Territory vs Posterior Circulation: Carotid (anterior circulation) TIAs typically affect face and arm > leg, with or without dysphasia. Posterior circulation TIAs cause cerebellar/brainstem symptoms: diplopia, vertigo, ataxia, bilateral symptoms, or isolated homonymous hemianopia.

Limb-Shaking TIA: A rare manifestation of severe carotid stenosis causing focal involuntary limb movements precipitated by postural changes or hypotension. Often misdiagnosed as focal motor seizures. Key distinguishing feature: triggered by standing/orthostatic stress and responds to carotid revascularization, not antiepileptic drugs. [10]

Don't Miss the Leg: Pure anterior cerebral artery (ACA) territory TIAs cause leg > arm weakness. Bilateral ACA involvement (rare) causes akinetic mutism. This is easily missed if examination focuses only on face/arm.

Duration Matters for Imaging: Symptom duration > 60 minutes predicts DWI positivity in ~50% of cases, reclassifying the event as a stroke. [2] This has implications for immediate management and prognosis.

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2. Epidemiology

Incidence and Prevalence

Stroke Risk Following TIA

The cardinal importance of TIA lies in its prediction of future stroke:

The EXPRESS study (2007) demonstrated that immediate treatment within 24 hours reduced 90-day stroke risk from 10.3% to 2.1%, a relative risk reduction of 80%. [6]

Risk Factors

Risk factors for TIA mirror those for ischaemic stroke:

Modifiable Risk Factors

Non-Modifiable Risk Factors

• Age: Risk doubles per decade after age 55 [11]
• Gender: Male > Female (until age 75, then equal) [11]
• Ethnicity: Black, South Asian, Hispanic populations at higher risk [12]
• Family History: First-degree relative with stroke increases risk 1.5-2× [14]
• Genetic: CADASIL, Fabry disease, sickle cell disease [16]

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3. Aetiology and Pathophysiology

Mechanisms of Cerebral Ischaemia

TIA results from temporary disruption of cerebral blood flow, sufficient to cause neurological dysfunction but insufficient duration or severity to cause permanent infarction. The key mechanisms are:

1. Thromboembolism (70-80%)

Arterial Sources:

• Large artery atherosclerosis: Carotid bifurcation, vertebral origin, basilar artery. Artery-to-artery embolism from unstable plaque. [15]
• Aortic arch atheroma: Particularly in elderly patients, severe (> 4mm) mobile atheroma is a significant embolic source. [17]

Cardiac Sources (Cardioembolic):

• Atrial fibrillation: Most common cardiac source (50% of cardioembolic TIA). [14]
• Valvular disease: Mitral stenosis, mechanical valves, endocarditis. [17]
• Intracardiac thrombus: Left ventricular thrombus post-MI, dilated cardiomyopathy. [17]
• Patent foramen ovale (PFO): Paradoxical embolism, particularly in young patients with cryptogenic TIA. [18]
• Atrial myxoma: Rare but important cause.

2. Haemodynamic Compromise (5-10%)

Cerebral hypoperfusion in the setting of severe arterial stenosis or occlusion:

• Mechanism: Severe (> 70%) stenosis or occlusion of major vessel + systemic hypotension or arrhythmia causes critical reduction in distal perfusion. [10]
• Watershed/Border-zone Ischaemia: Affects areas between major vascular territories (ACA/MCA, MCA/PCA). [19]
• Limb-shaking TIA: Involuntary limb movements due to critical carotid stenosis with inadequate collateral flow. Symptoms triggered by orthostatic stress. [10]

3. Small Vessel Disease/Lacunar (15-20%)

• Mechanism: Lipohyalinosis or microatheroma affecting small penetrating arteries (lenticulostriate, pontine perforators). [20]
• Lacunar Syndromes: Pure motor stroke, pure sensory stroke, ataxic hemiparesis, dysarthria-clumsy hand syndrome. [20]
• Risk Factors: Hypertension, diabetes, smoking. [20]

4. Other/Uncommon Causes (less than 5%)

• Arterial Dissection: Carotid or vertebral dissection (young patients, trauma/neck manipulation). [21]
• Vasculitis: Giant cell arteritis (> 50 years + ESR/CRP elevation), primary CNS vasculitis, systemic vasculitides. [22]
• Hypercoagulable States: Antiphospholipid syndrome, protein C/S deficiency, Factor V Leiden, malignancy. [23]
• Haematological: Polycythaemia, thrombocytosis, sickle cell disease. [23]
• Substance Use: Cocaine, amphetamines (vasospasm). [24]

Molecular Pathophysiology

Exam Detail: Ischaemic Cascade in TIA:

Unlike stroke, TIA involves temporary ischaemia without progression to irreversible cellular injury:

1. Cerebral Blood Flow Reduction: Normal CBF is 50-60 mL/100g/min. Neurological dysfunction occurs when CBF drops to 15-20 mL/100g/min (ischaemic penumbra). [19]

2. Neuronal Dysfunction: Failure of ATP-dependent ion pumps → membrane depolarization → rapid symptoms (seconds to minutes).

3. Ischaemic Penumbra: Tissue at risk of infarction but still viable. In TIA, reperfusion occurs before irreversible damage (typically less than 10 minutes of critical ischaemia). [19]

4. Reperfusion: Spontaneous recanalization (clot lysis/fragmentation) or collateral flow restoration → rapid symptom resolution.

5. No Infarction: Unlike stroke, no progression to necrosis/apoptosis. DWI-MRI remains negative (or shows only small infarcts that were likely asymptomatic). [2]

Why Does Reperfusion Occur in TIA?

• Small embolic burden (spontaneous fragmentation/lysis)
• Robust collateral circulation (Circle of Willis)
• Favourable rheology (good cardiac output, normal blood pressure)
• Endogenous fibrinolysis

TOAST Classification

The TOAST (Trial of Org 10172 in Acute Stroke Treatment) classification categorizes ischaemic cerebrovascular events:

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4. Clinical Presentation

Symptoms and Signs

TIA presents with sudden onset focal neurological deficits corresponding to a specific vascular territory. Symptoms are characteristically:

• Negative (loss of function) rather than positive
• Focal rather than global
• Maximal at onset (not progressive/fluctuating in real-time)
• Brief duration: Most resolve within 60 minutes; less than 24 hours by definition

Anterior Circulation (Carotid Territory) TIAs

Internal Carotid/Middle Cerebral Artery (ICA/MCA):

Amaurosis Fugax (Retinal/Ophthalmic Artery):

• Presentation: Painless, transient monocular vision loss described as a "curtain descending" or "shade being pulled down" over one eye.
• Duration: Typically seconds to minutes (rarely > 15 minutes).
• Mechanism: Embolic occlusion of ophthalmic or central retinal artery from ipsilateral carotid stenosis. [7]
• Clinical Significance: Indicates severe ipsilateral ICA disease; mandates urgent carotid imaging. [7]

Anterior Cerebral Artery (ACA):

• Classic: Contralateral leg > arm weakness/numbness.
• Rare: Bilateral ACA involvement (e.g., anterior communicating artery territory) causes akinetic mutism, abulia. [26]

Posterior Circulation (Vertebrobasilar) TIAs

Vertebral/Basilar Arteries:

Important: Isolated vertigo, isolated diplopia, or isolated dysphagia are rarely due to TIA and should prompt consideration of alternative diagnoses (peripheral vestibular, ocular, or local pharyngeal causes). [27]

Atypical Presentations and Mimics

Symptoms that are NOT typical of TIA:

Differential Diagnosis

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5. Risk Stratification: ABCD2 Score

The ABCD2 Score

Developed to predict stroke risk following TIA, the ABCD2 score assigns points based on five clinical features: [4]

Risk Stratification

Modern Clinical Application

Important Limitations:

1. Limited Sensitivity: ABCD2 score was developed before widespread MRI use and does not incorporate imaging findings (e.g., DWI positivity, carotid stenosis). [36]

2. Cannot Rule Out High-Risk Features: A low ABCD2 score does not exclude high-risk features such as:

   • Atrial fibrillation
   • Symptomatic carotid stenosis > 50%
   • Crescendo TIA
   • DWI-positive lesions

3. Current NICE Guidance (NG128): Recommends that all patients with suspected TIA should:

   • Receive aspirin 300mg immediately (unless contraindicated)
   • Be assessed by a specialist within 24 hours
   • Have urgent brain imaging (MRI preferred) and carotid imaging
   • The ABCD2 score is not used to delay assessment or treatment. [1]

Clinical Utility:

The ABCD2 score retains value for:

• Prognostic counselling: Explaining stroke risk to patients
• Research stratification: Clinical trial enrollment
• Resource allocation: In systems where same-day assessment is not universally available (though this is not best practice)

Exam Detail: EXPRESS Study Impact:

The EXPRESS study (2007) fundamentally changed TIA management by demonstrating that immediate treatment (within 24 hours) reduced 90-day stroke risk from 10.3% to 2.1%. [6] This shifted the paradigm from "risk stratification for delayed assessment" to "all TIAs are emergencies requiring immediate treatment."

As a result, guidelines (NICE, AHA/ASA) now recommend:

• Same-day or next-day assessment for all TIAs
• Immediate aspirin 300mg
• Imaging and specialist review within 24 hours

The ABCD2 score is therefore no longer used to triage TIA patients for delayed assessment, but remains a validated prognostic tool.

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6. Investigations

Immediate Bedside Investigations

All patients with suspected TIA require immediate assessment to:

1. Confirm the diagnosis (exclude TIA mimics)
2. Identify mechanism/aetiology
3. Stratify stroke risk
4. Initiate secondary prevention

Laboratory Investigations

Brain Imaging

MRI Brain (Diffusion-Weighted Imaging - DWI):

• Gold Standard: DWI detects acute ischaemia within minutes of onset and is far superior to CT. [2]

• Timing: Perform within 24 hours of symptom onset (NICE NG128). [1]
• Sensitivity: DWI is positive in 30-50% of clinically diagnosed TIAs, particularly if symptoms lasted > 60 minutes. [2]

CT Head:

• Role: Less sensitive than MRI; mainly used to exclude haemorrhage if MRI unavailable or contraindicated, or if urgent anticoagulation planned. [1]
• Limitations: Poor sensitivity for acute small infarcts, posterior fossa lesions. [39]
• When Sufficient: If MRI unavailable and clinical confidence in TIA diagnosis is high, CT can exclude major structural lesions/haemorrhage.

Vascular Imaging

Carotid Doppler Ultrasound:

• Indication: Mandatory for all anterior circulation (carotid territory) TIAs. [1]

• Timing: Within 24 hours if patient is a candidate for carotid intervention. [1]

• Measurement: Stenosis is quantified using NASCET criteria (North American Symptomatic Carotid Endarterectomy Trial):

  NASCET % Stenosis = [(1 - D_stenosis / D_{normal distal ICA}) × 100]

• Limitations: Operator-dependent; may overestimate or underestimate stenosis; calcification can obscure accurate measurement.

CT Angiography (CTA) or MR Angiography (MRA):

• Indication: If carotid ultrasound is inconclusive, or to assess intracranial circulation/posterior circulation. [1]
• CTA: Fast, widely available; requires IV contrast; excellent for visualising stenosis, occlusion, dissection. [40]
• MRA: No radiation or iodinated contrast; good for intracranial vessels; can be combined with brain MRI. [40]
• Use in Posterior Circulation TIA: MRA/CTA of vertebrobasilar system if posterior circulation symptoms. [1]

Cardiac Investigations

12-Lead ECG:

• Immediate: Detect atrial fibrillation (present in 10-20% of TIA patients). [14]

24-48 Hour Holter Monitoring:

• Indication: If ECG normal but suspicion of paroxysmal AF (cryptogenic TIA, embolic pattern on imaging, elderly patient). [41]
• Yield: Detects paroxysmal AF in 5-10% of patients with normal baseline ECG. [41]

Transthoracic Echocardiography (TTE):

• Indication: Suspected cardioembolic source (AF, heart failure, valvular disease, recent MI). [1]
• Findings: LV thrombus, valve vegetations/stenosis, reduced ejection fraction, regional wall motion abnormalities. [17]

Transoesophageal Echocardiography (TOE):

• Indication: Young patient (less than 60) with cryptogenic TIA to detect:

  • "Patent Foramen Ovale (PFO): Present in 25% of population; paradoxical embolism. [18]"
  • "Atrial Septal Aneurysm: Associated with PFO and increased stroke risk. [18]"
  • "Left Atrial Appendage Thrombus: In AF patients. [42]"
  • "Aortic Arch Atheroma: > 4mm thickness is embolic source. [17]"

• Bubble Study: Agitated saline injection to detect right-to-left shunt (PFO). [18]

Summary Investigation Pathway

SUSPECTED TIA
      ↓
IMMEDIATE (Within 1 hour):
- Blood glucose
- BP measurement
- ECG
- Aspirin 300mg
      ↓
URGENT (Within 24 hours):
- MRI Brain (DWI)
- Carotid Doppler (if anterior circulation)
- Blood tests (FBC, U&E, Lipids, HbA1c, ESR if > 50 years)
      ↓
SPECIALIST ASSESSMENT:
- TIA Clinic review
- Risk stratification
- Initiate secondary prevention
      ↓
FURTHER WORKUP (as indicated):
- 24h Holter (if no AF on ECG)
- Echocardiography (TTE ± TOE)
- CT/MR Angiography (if carotid US inconclusive)
- Thrombophilia screen (young, cryptogenic, recurrent)

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7. Management

Acute Management (Within 24 Hours)

The EXPRESS study established that immediate initiation of secondary prevention within 24 hours of TIA reduces 90-day stroke risk by 80% (from 10.3% to 2.1%). [6] Current management reflects this urgency.

1. Immediate Antiplatelet Therapy

Aspirin 300mg Stat Dose:

• Give immediately on diagnosis of suspected TIA (pre-hospital, ED, or primary care). [1]
• Contraindications: Active bleeding, anticoagulation already in situ, known aspirin allergy.
• Evidence: Aspirin reduces early stroke recurrence by ~30% when started within 48 hours. [43]
• Duration: Continue 300mg daily for 14 days, then step down to long-term antiplatelet (see below).

Dual Antiplatelet Therapy (DAPT):

Recent trials (CHANCE, POINT) have investigated short-term DAPT (aspirin + clopidogrel) for high-risk TIA/minor stroke:

Current NICE Guidance (NG128):

• NICE does not routinely recommend DAPT for TIA. [1]
• Aspirin 300mg for 14 days, then long-term clopidogrel monotherapy is standard. [1]

When to Consider DAPT:

Some specialist centres use short-term DAPT (21 days) for:

• High-risk TIA (ABCD2 ≥4, large artery stenosis, recurrent events)
• Minor stroke (NIHSS ≤3) with imaging evidence

This is not universal UK practice; discuss with local stroke team.

2. Urgent Referral and Assessment

TIA Clinic/Stroke Service:

• All patients should be assessed by a specialist within 24 hours. [1]
• Crescendo TIA (recurrent events within a week) requires immediate hospital admission. [8]

Specialist Assessment Includes:

• Confirm diagnosis (exclude mimics)
• Review imaging (MRI brain, carotid Doppler)
• Identify stroke mechanism (TOAST classification)
• Initiate/optimize secondary prevention
• Arrange further investigations (Holter, echo)
• Provide patient education and driving advice

Secondary Prevention (Long-Term)

1. Antiplatelet Therapy

Clopidogrel 75mg Once Daily (First-Line):

• Evidence: CAPRIE trial showed clopidogrel superior to aspirin for secondary prevention of vascular events (relative risk reduction 8.7%). [46]
• Duration: Lifelong.
• Alternative: If clopidogrel intolerant or contraindicated, use aspirin 75mg + dipyridamole MR 200mg BD. [1]

Aspirin + Dipyridamole:

• Evidence: ESPRIT and ESPS-2 trials showed combination superior to aspirin alone (relative risk reduction ~20%). [47]
• Limitation: Dipyridamole poorly tolerated (headache, flushing, GI upset in 25-30%). [47]

Aspirin Monotherapy:

• 75-100mg daily: Only if clopidogrel and aspirin+dipyridamole are both contraindicated/intolerant. [1]

2. Anticoagulation (for Atrial Fibrillation)

If AF is detected (permanent, persistent, or paroxysmal), anticoagulation is indicated:

Direct Oral Anticoagulants (DOACs) - First-Line:

Warfarin:

• Target INR 2-3 for non-valvular AF. [1]
• Use if: DOAC contraindicated, severe renal impairment (CrCl less than 15), mechanical heart valve, rheumatic mitral stenosis. [1]

Timing of Anticoagulation Initiation:

• After imaging excludes haemorrhage: Immediate if DWI-negative or small infarct. [1]
• Large infarct: Delay 1-2 weeks due to haemorrhagic transformation risk. [52]

CHA2DS2-VASc Score:

Risk stratification for stroke in AF (though treatment threshold is ≥1 for men, ≥2 for women): [14]

Score ≥2: Anticoagulation indicated (men); ≥3 (women). [14]

3. Lipid Management

Atorvastatin 80mg Once Daily:

• All patients with TIA should receive high-intensity statin therapy regardless of baseline cholesterol. [1]
• Evidence: SPARCL trial showed atorvastatin 80mg reduced stroke recurrence by 16% in patients with recent stroke/TIA. [53]
• Target: Not treat-to-target; "fire and forget" approach. [1]
• Monitoring: Check lipids and LFTs at 3 months; only adjust if intolerant.

4. Blood Pressure Management

Target BP: less than 130/80 mmHg:

• All TIA patients benefit from BP lowering (even if not hypertensive). [54]
• Timing: Do not lower BP acutely (first 24-48 hours) unless hypertensive emergency; allow permissive hypertension to maintain cerebral perfusion. [1]
• Chronic Management: Start/optimize antihypertensives after acute period (usually 1-2 weeks). [54]

Preferred Agents:

• ACE Inhibitor (e.g., ramipril 10mg) or ARB (e.g., candesartan 32mg): PROGRESS trial showed perindopril + indapamide reduced stroke recurrence by 28%. [54]
• Thiazide Diuretic (e.g., indapamide 2.5mg SR): Often used in combination.
• Calcium Channel Blocker (e.g., amlodipine 10mg): Alternative or additional agent.

5. Glycaemic Control

• Target HbA1c: ≤53 mmol/mol (7%) in diabetic patients. [1]
• Avoid Hypoglycaemia: Tight control (HbA1c less than 48) not shown to reduce stroke risk and increases hypoglycaemia. [55]

6. Lifestyle Modification

• Smoking Cessation: Mandatory; reduces stroke risk by 50% within 2-5 years. [56]
• Alcohol Reduction: Limit to ≤14 units per week. [1]
• Diet: Mediterranean diet; reduce saturated fat, increase fruit/vegetables. [1]
• Exercise: ≥150 minutes moderate-intensity per week. [1]
• Weight Management: Target BMI 18.5-24.9 kg/m². [1]

Carotid Intervention

Carotid Endarterectomy (CEA):

Surgical removal of atherosclerotic plaque from the carotid bifurcation to prevent recurrent stroke.

Indications

NASCET/ECST Trials:

NICE Recommendations:

• Symptomatic stenosis 50-99%: Offer CEA. [1]
• Timing: Within 2 weeks of symptom onset (ideally 1 week). [1]
• Rationale: Stroke risk highest in first 2 weeks; early surgery maximally reduces recurrence. [57]

Carotid Artery Stenting (CAS)

• Alternative to CEA: For patients at high surgical risk (hostile neck, previous neck surgery/radiation, severe cardiac/pulmonary disease). [58]
• Evidence: CREST trial showed CAS non-inferior to CEA for long-term stroke prevention, but higher periprocedural stroke risk. [58]
• Current Practice: CEA remains first-line; CAS reserved for specific cases. [1]

Perioperative Risk

• Acceptable combined stroke/death rate: less than 6% for symptomatic stenosis. [1]
• Complications: Stroke (2-3%), MI (1-2%), cranial nerve injury (5-7%, usually temporary), haematoma. [59]

Management Algorithm

SUSPECTED TIA (Focal symptoms, less than 24h)
              ↓
      ASPIRIN 300mg STAT
   (unless on anticoagulation)
              ↓
    URGENT TIA CLINIC (less than 24h)
              ↓
     ┌────────┴────────┐
     ↓                 ↓
MRI BRAIN (DWI)   CAROTID DOPPLER
     ↓                 ↓
CONFIRM TIA       ASSESS STENOSIS
(DWI-negative)         ↓
     ↓           ┌─────┴─────┐
     ↓           ↓           ↓
ANTIPLATELET  50-99%      less than 50%
(Clopidogrel   Stenosis   Stenosis
75mg OD)          ↓           ↓
     ↓        CEA within   Medical
STATIN        2 weeks      Only
(Atorvastatin ↓            ↓
80mg)      Clopidogrel  Clopidogrel
     ↓      + Statin     + Statin
BP CONTROL    ↓            ↓
(less than 130/80)     └────┬───────┘
     ↓             ↓
     └──────┬──────┘
            ↓
    ATRIAL FIBRILLATION?
            ↓
       ┌────┴────┐
       ↓         ↓
      YES        NO
       ↓         ↓
ANTICOAGULATION Continue
(DOAC preferred) Antiplatelet
       ↓         ↓
       └────┬────┘
            ↓
    LIFESTYLE MODIFICATION
    - Smoking cessation
    - Alcohol reduction
    - Exercise, diet
    - Driving advice

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8. Complications

1. Recurrent Stroke

• Risk: Highest complication; 10-20% within 90 days if untreated. [3,4]
• Prevention: Urgent antiplatelet/anticoagulation, risk factor modification, carotid intervention if indicated. [6]
• Prognosis: Early treatment reduces risk by 80%. [6]

2. Silent Cerebral Infarction

• Prevalence: 30-50% of TIA patients have DWI-positive lesions (small infarcts) despite symptom resolution. [2]
• Significance: Cumulative cognitive decline; increased dementia risk. [38]
• Management: Aggressive secondary prevention.

3. Vascular Dementia

• Mechanism: Recurrent subclinical infarcts, white matter disease, strategic infarcts (thalamus). [60]
• Risk: Increases with each recurrent event and uncontrolled vascular risk factors. [60]
• Prevention: Secondary prevention, BP control, avoid recurrent strokes. [60]

4. Perioperative Complications of CEA

• Stroke/Death: 2-3% risk (acceptable threshold less than 6%). [59]
• Myocardial Infarction: 1-2%. [59]
• Cranial Nerve Injury: 5-7% (hypoglossal, vagus, facial); usually temporary. [59]
• Haematoma: May require re-operation if compromises airway. [59]

5. Bleeding Complications

• Antiplatelet Therapy: GI bleeding, intracranial haemorrhage (0.1-0.3% per year). [46]
• Anticoagulation: Major bleeding 2-3% per year on DOACs, 3-4% on warfarin. [48]
• Mitigation: PPI for GI protection; careful patient selection; avoid DAPT if not indicated.

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9. Prognosis and Outcomes

Stroke Risk Without Treatment

Stroke Risk With Optimal Treatment

Prognostic Factors (Worse Prognosis)

• High ABCD2 Score (6-7): 8-12% stroke risk within 7 days. [4]
• DWI-Positive Lesions: 5-6× increased stroke risk compared to DWI-negative. [2]
• Symptomatic Carotid Stenosis > 50%: High recurrence without intervention. [15]
• Atrial Fibrillation: 5-7× stroke risk if not anticoagulated. [14]
• Multiple Vascular Risk Factors: Diabetes, hypertension, smoking. [14]
• Recurrent/Crescendo TIA: Indicates unstable plaque or critical stenosis. [8]

Functional Outcomes

• TIA Itself: By definition, no residual deficit.
• Subsequent Stroke: 30-40% of strokes following TIA are disabling. [13]
• Cognitive Decline: Silent infarcts contribute to vascular cognitive impairment over time. [60]

Mortality

• 1-Year Mortality: 5-10% (predominantly cardiovascular causes). [13]
• 5-Year Mortality: 20-30%. [13]
• Cause: Myocardial infarction, recurrent stroke, other vascular events. [13]

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10. Evidence and Guidelines

Key Guidelines

Landmark Studies

1. NASCET & ECST (1991-1998)

Topic: Carotid Endarterectomy for Symptomatic Stenosis

• NASCET: North American Symptomatic Carotid Endarterectomy Trial
• ECST: European Carotid Surgery Trial

Key Findings:

• 70-99% stenosis: CEA reduced 2-year stroke risk from 26% to 9% (ARR 17%, NNT 6). [15]
• 50-69% stenosis: CEA reduced 5-year stroke risk from 22.2% to 15.7% (ARR 6.5%, NNT 15). [15]
• less than 50% stenosis: No benefit from CEA. [15]

Impact: Established stenosis thresholds for surgical intervention; CEA remains standard of care for symptomatic high-grade stenosis.

DOI: 10.1056/NEJM199108153250701

2. EXPRESS Study (2007)

Topic: Early vs Delayed Treatment After TIA

Design: Before-and-after comparison of TIA management at a single UK centre.

Intervention:

• Before: Standard care (clinic assessment within 1-2 weeks)
• After: Immediate assessment and treatment within 24 hours (aspirin, statin, BP control, imaging, CEA if indicated)

Results:

• 90-day stroke risk: Reduced from 10.3% to 2.1% (ARR 8.2%, relative risk reduction 80%).
• Early stroke risk (first 7 days) reduced from 5.9% to 0.9%.

Impact: Transformed TIA management paradigm; led to NICE recommendation for less than 24h assessment. [6]

DOI: 10.1016/S0140-6736(07)61450-4

3. CHANCE Trial (2013)

Topic: Dual Antiplatelet Therapy (DAPT) in Minor Stroke/High-Risk TIA

Population: Chinese patients with minor stroke (NIHSS ≤3) or high-risk TIA (ABCD2 ≥4) within 24 hours of onset.

Intervention: Aspirin + clopidogrel for 21 days vs aspirin alone.

Results:

• 90-day stroke risk: 8.2% (DAPT) vs 11.7% (aspirin) (HR 0.68, pless than 0.001).
• Moderate/severe bleeding: 0.3% vs 0.0% (p=0.01, but very low absolute rate).

Limitations: Chinese population; may not generalize to other ethnicities.

Impact: Supported use of short-term DAPT for high-risk TIA; not universally adopted in UK (NICE does not recommend). [44]

DOI: 10.1056/NEJMoa1215340

4. POINT Trial (2018)

Topic: Dual Antiplatelet Therapy in Minor Stroke/High-Risk TIA

Population: International, minor stroke/TIA within 12 hours of onset.

Intervention: Aspirin + clopidogrel for 90 days vs aspirin alone.

Results:

• 90-day stroke risk: 5.0% (DAPT) vs 6.5% (aspirin) (HR 0.75, p=0.02).
• Major haemorrhage: 0.9% (DAPT) vs 0.4% (aspirin) (HR 2.32, p=0.02).

Impact: Confirmed benefit of DAPT but highlighted bleeding risk; supports shorter duration (21 days) rather than 90 days. [45]

DOI: 10.1056/NEJMoa1800410

5. SPARCL Trial (2006)

Topic: Atorvastatin for Stroke Prevention in Stroke/TIA Patients

Population: Patients with stroke/TIA in previous 6 months, no known CHD.

Intervention: Atorvastatin 80mg vs placebo.

Results:

• 5-year stroke risk: 11.2% (atorvastatin) vs 13.1% (placebo) (ARR 1.9%, RRR 16%, p=0.03).
• Haemorrhagic stroke: Slightly increased with atorvastatin (2.3% vs 1.4%).

Impact: Established high-dose statin as standard for secondary prevention post-TIA/stroke. [53]

DOI: 10.1056/NEJMoa061894

6. CAPRIE Trial (1996)

Topic: Clopidogrel vs Aspirin for Secondary Prevention

Population: Patients with recent stroke, MI, or PAD.

Intervention: Clopidogrel 75mg vs aspirin 325mg.

Results:

• Annual risk of vascular events: 5.32% (clopidogrel) vs 5.83% (aspirin) (RRR 8.7%, p=0.043).
• Benefit greatest in PAD subgroup, but significant overall.

Impact: Established clopidogrel as preferred antiplatelet for secondary prevention. [46]

DOI: 10.1016/S0140-6736(96)09457-3

7. PROGRESS Trial (2001)

Topic: Blood Pressure Lowering for Stroke Prevention

Population: Patients with stroke/TIA.

Intervention: Perindopril (ACE inhibitor) + indapamide (diuretic) vs placebo.

Results:

• 4-year stroke risk: Reduced by 28% (HR 0.72, pless than 0.0001).
• Combination therapy: Greater benefit than perindopril alone (43% vs 5% RRR).

Impact: Established BP lowering (combination ACE inhibitor + diuretic) as key secondary prevention strategy. [54]

DOI: 10.1016/S0140-6736(01)06178-5

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11. Patient and Layperson Explanation

What is a TIA?

A Transient Ischaemic Attack (TIA), often called a "mini-stroke," happens when a blood clot temporarily blocks an artery in your brain. This causes sudden symptoms like weakness on one side of your body, difficulty speaking, or loss of vision.

The key difference from a stroke is that in a TIA, the blockage clears on its own (usually within minutes to an hour), and the symptoms go away completely. There is no permanent damage to the brain.

Why is it serious?

Even though the symptoms go away, a TIA is a major warning sign. It means you have conditions (like narrowed arteries or blood clots from the heart) that put you at high risk of having a full stroke in the near future.

Without treatment, 1 in 10 people who have a TIA will have a major stroke within the next few days or weeks.

What causes a TIA?

The most common causes are:

1. Narrowed arteries in the neck (carotid arteries) due to fatty plaques (atherosclerosis). Small pieces of plaque can break off and travel to the brain.
2. Irregular heartbeat (atrial fibrillation) that allows clots to form in the heart and travel to the brain.
3. High blood pressure, diabetes, high cholesterol, and smoking all increase your risk.

What are the symptoms?

Remember FAST:

• Face: Drooping on one side, difficulty smiling
• Arms: Weakness or numbness in one arm
• Speech: Slurred speech or difficulty finding words
• Time: Call 999 immediately if you see any of these signs

Other symptoms include:

• Loss of vision in one eye (like a curtain coming down)
• Dizziness, loss of balance, or difficulty walking
• Sudden confusion

Important: Symptoms come on suddenly and usually go away within an hour.

What tests will I need?

• Brain scan (MRI): To check for any damage and rule out a stroke.
• Ultrasound of your neck arteries: To see if they are narrowed.
• Heart tracing (ECG): To check for irregular heartbeat.
• Blood tests: To check cholesterol, blood sugar, and other risk factors.

What is the treatment?

Immediate treatment (within 24 hours):

• Aspirin: A "blood-thinning" tablet to prevent clots.
• Urgent assessment by a stroke specialist.

Long-term treatment (to prevent a stroke):

1. Antiplatelet medication: Clopidogrel (or aspirin) every day to stop clots forming.
2. Cholesterol-lowering medication: Atorvastatin (a "statin") to reduce fatty plaques.
3. Blood pressure control: Medications to keep your blood pressure below 130/80.
4. Blood thinners (if you have atrial fibrillation): Such as apixaban or rivaroxaban.
5. Surgery on neck arteries (if severely narrowed): Called carotid endarterectomy, performed within 2 weeks to clean out the plaque.

Lifestyle changes:

• Stop smoking (the single most important thing you can do)
• Eat a healthy diet (Mediterranean-style: lots of vegetables, fish, olive oil)
• Exercise regularly (at least 150 minutes per week)
• Lose weight if overweight
• Reduce alcohol intake

Can I drive?

No, not for 1 month. You must not drive for at least 4 weeks after a TIA. You do not need to tell the DVLA unless you still have symptoms after 1 month, or if you drive a bus or lorry.

What is the outlook?

With prompt treatment and lifestyle changes, your risk of having a stroke can be reduced by up to 80%. Most people who have a TIA go on to live normal, healthy lives—but only if they take their medications and make necessary lifestyle changes.

Key message: A TIA is your body's warning. Take it seriously, take your medications, and make healthy changes to prevent a stroke.

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12. References

Primary Sources

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10. Persoon S, Kappelle LJ, Klijn CJ. Limb-shaking transient ischaemic attacks in patients with internal carotid artery occlusion: a case-control study. Brain. 2010;133(Pt 3):915-922. DOI: 10.1093/brain/awp331

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15. Barnett HJM, Taylor DW, Haynes RB, et al. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators. N Engl J Med. 1991;325(7):445-453. DOI: 10.1056/NEJM199108153250701

16. Markus HS. Cerebral small vessel disease: mechanisms and clinical implications. Lancet Neurol. 2019;18(7):684-696. DOI: 10.1016/S1474-4422(19)30079-1

17. Pearson AC, Labovitz AJ, Tatineni S, Gomez CR. Superiority of transesophageal echocardiography in detecting cardiac source of embolism in patients with cerebral ischemia of uncertain etiology. J Am Coll Cardiol. 1991;17(1):66-72. DOI: 10.1016/0735-1097(91)90705-3

18. Hagen PT, Scholz DG, Edwards WD. Incidence and size of patent foramen ovale during the first 10 decades of life: an autopsy study of 965 normal hearts. Mayo Clin Proc. 1984;59(1):17-20. DOI: 10.1016/S0025-6196(12)60336-X

19. Baron JC, Bousser MG, Rey A, Guillard A, Comar D, Castaigne P. Reversal of focal "misery-perfusion syndrome" by extra-intracranial arterial bypass in hemodynamic cerebral ischemia. Stroke. 1981;12(4):454-459. DOI: 10.1161/01.STR.12.4.454

20. Fisher CM. Lacunar strokes and infarcts: a review. Neurology. 1982;32(8):871-876. DOI: 10.1212/WNL.32.8.871

21. Debette S, Leys D. Cervical-artery dissections: predisposing factors, diagnosis, and outcome. Lancet Neurol. 2009;8(7):668-678. DOI: 10.1016/S1474-4422(09)70084-5

22. Salvarani C, Cantini F, Hunder GG. Polymyalgia rheumatica and giant-cell arteritis. Lancet. 2008;372(9634):234-245. DOI: 10.1016/S0140-6736(08)61077-6

23. Bick RL. Antiphospholipid thrombosis syndromes. Hematol Oncol Clin North Am. 2003;17(1):115-147. DOI: 10.1016/S0889-8588(02)00069-8

24. Westover AN, McBride S, Haley RW. Stroke in young adults who abuse amphetamines or cocaine: a population-based study of hospitalized patients. Arch Gen Psychiatry. 2007;64(4):495-502. DOI: 10.1001/archpsyc.64.4.495

25. Adams HP Jr, Bendixen BH, Kappelle LJ, et al. Classification of subtype of acute ischemic stroke. Definitions for use in a multicenter clinical trial. TOAST. Trial of Org 10172 in Acute Stroke Treatment. Stroke. 1993;24(1):35-41. DOI: 10.1161/01.STR.24.1.35

26. Caplan LR. Posterior circulation ischemia: then, now, and tomorrow. The Thomas Willis Lecture-2000. Stroke. 2000;31(8):2011-2023. DOI: 10.1161/01.STR.31.8.2011

27. Kerber KA, Brown DL, Lisabeth LD, Smith MA, Morgenstern LB. Stroke among patients with dizziness, vertigo, and imbalance in the emergency department: a population-based study. Stroke. 2006;37(10):2484-2487. DOI: 10.1161/01.STR.0000240329.48263.0d

28. Fisher CM. Late-life migraine accompaniments as a cause of unexplained transient ischemic attacks. Can J Neurol Sci. 1980;7(1):9-17. DOI: 10.1017/S0317167100022927

29. Rumbach L, Sablot D, Berger E, Tatu L, Vuillier F, Moulin T. Status epilepticus in stroke: report on a hospital-based stroke cohort. Neurology. 2000;54(2):350-354. DOI: 10.1212/WNL.54.2.350

30. Malouf R, Brust JC. Hypoglycemia: causes, neurological manifestations, and outcome. Ann Neurol. 1985;17(5):421-430. DOI: 10.1002/ana.410170502

31. Kapoor WN. Syncope. N Engl J Med. 2000;343(25):1856-1862. DOI: 10.1056/NEJM200012213432507

32. Hodges JR, Warlow CP. Syndromes of transient amnesia: towards a classification. A study of 153 cases. J Neurol Neurosurg Psychiatry. 1990;53(10):834-843. DOI: 10.1136/jnnp.53.10.834

33. Stone J, Carson A, Duncan R, et al. Who is referred to neurology clinics?—the diagnoses made in 3781 new patients. Clin Neurol Neurosurg. 2010;112(9):747-751. DOI: 10.1016/j.clineuro.2010.05.011

34. Polman CH, Reingold SC, Banwell B, et al. Diagnostic criteria for multiple sclerosis: 2010 revisions to the McDonald criteria. Ann Neurol. 2011;69(2):292-302. DOI: 10.1002/ana.22366

35. Ay H, Buonanno FS, Rordorf G, et al. Normal diffusion-weighted MRI during stroke-like deficits. Neurology. 1999;52(9):1784-1792. DOI: 10.1212/WNL.52.9.1784

36. Giles MF, Rothwell PM. Systematic review and pooled analysis of published and unpublished validations of the ABCD and ABCD2 transient ischemic attack risk scores. Stroke. 2010;41(4):667-673. DOI: 10.1161/STROKEAHA.109.571174

37. Ovbiagele B, Saver JL. Cerebral white matter hyperintensities on MRI: current concepts and therapeutic implications. Cerebrovasc Dis. 2006;22(2-3):83-90. DOI: 10.1159/000093235

38. Vermeer SE, Longstreth WT Jr, Koudstaal PJ. Silent brain infarcts: a systematic review. Lancet Neurol. 2007;6(7):611-619. DOI: 10.1016/S1474-4422(07)70170-9

39. Chalela JA, Kidwell CS, Nentwich LM, et al. Magnetic resonance imaging and computed tomography in emergency assessment of patients with suspected acute stroke: a prospective comparison. Lancet. 2007;369(9558):293-298. DOI: 10.1016/S0140-6736(07)60151-2

40. Bash S, Villablanca JP, Jahan R, et al. Intracranial vascular stenosis and occlusive disease: evaluation with CT angiography, MR angiography, and digital subtraction angiography. AJNR Am J Neuroradiol. 2005;26(5):1012-1021. PMID: 15891154

41. Gladstone DJ, Spring M, Dorian P, et al. Atrial fibrillation in patients with cryptogenic stroke. N Engl J Med. 2014;370(26):2467-2477. DOI: 10.1056/NEJMoa1311376

42. Stoddard MF, Dawkins PR, Prince CR, Ammash NM. Left atrial appendage thrombus is not uncommon in patients with acute atrial fibrillation and a recent embolic event: a transesophageal echocardiographic study. J Am Coll Cardiol. 1995;25(2):452-459. DOI: 10.1016/0735-1097(94)00396-8

43. Rothwell PM, Algra A, Chen Z, Diener HC, Norrving B, Mehta Z. Effects of aspirin on risk and severity of early recurrent stroke after transient ischaemic attack and ischaemic stroke: time-course analysis of randomised trials. Lancet. 2016;388(10042):365-375. DOI: 10.1016/S0140-6736(16)30468-8

44. Wang Y, Wang Y, Zhao X, et al. Clopidogrel with aspirin in acute minor stroke or transient ischemic attack (CHANCE). N Engl J Med. 2013;369(1):11-19. DOI: 10.1056/NEJMoa1215340

45. Johnston SC, Easton JD, Farrant M, et al. Clopidogrel and aspirin in acute ischemic stroke and high-risk TIA (POINT). N Engl J Med. 2018;379(3):215-225. DOI: 10.1056/NEJMoa1800410

46. CAPRIE Steering Committee. A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). Lancet. 1996;348(9038):1329-1339. DOI: 10.1016/S0140-6736(96)09457-3

47. Halkes PH, van Gijn J, Kappelle LJ, Koudstaal PJ, Algra A; ESPRIT Study Group. Aspirin plus dipyridamole versus aspirin alone after cerebral ischaemia of arterial origin (ESPRIT): randomised controlled trial. Lancet. 2006;367(9523):1665-1673. DOI: 10.1016/S0140-6736(06)68734-5

48. Granger CB, Alexander JH, McMurray JJ, et al. Apixaban versus warfarin in patients with atrial fibrillation. N Engl J Med. 2011;365(11):981-992. DOI: 10.1056/NEJMoa1107039

49. Patel MR, Mahaffey KW, Garg J, et al. Rivaroxaban versus warfarin in nonvalvular atrial fibrillation. N Engl J Med. 2011;365(10):883-891. DOI: 10.1056/NEJMoa1009638

50. Giugliano RP, Ruff CT, Braunwald E, et al. Edoxaban versus warfarin in patients with atrial fibrillation. N Engl J Med. 2013;369(22):2093-2104. DOI: 10.1056/NEJMoa1310907

51. Connolly SJ, Ezekowitz MD, Yusuf S, et al. Dabigatran versus warfarin in patients with atrial fibrillation. N Engl J Med. 2009;361(12):1139-1151. DOI: 10.1056/NEJMoa0905561

52. Sandercock PA, Counsell C, Kane EJ. Anticoagulants for acute ischaemic stroke. Cochrane Database Syst Rev. 2015;2015(3):CD000024. DOI: 10.1002/14651858.CD000024.pub4

53. Amarenco P, Bogousslavsky J, Callahan A 3rd, et al. High-dose atorvastatin after stroke or transient ischemic attack (SPARCL). N Engl J Med. 2006;355(6):549-559. DOI: 10.1056/NEJMoa061894

54. PROGRESS Collaborative Group. Randomised trial of a perindopril-based blood-pressure-lowering regimen among 6,105 individuals with previous stroke or transient ischaemic attack. Lancet. 2001;358(9287):1033-1041. DOI: 10.1016/S0140-6736(01)06178-5

55. ACCORD Study Group. Effects of intensive glucose lowering in type 2 diabetes. N Engl J Med. 2008;358(24):2545-2559. DOI: 10.1056/NEJMoa0802743

56. Wolf PA, D'Agostino RB, Kannel WB, Bonita R, Belanger AJ. Cigarette smoking as a risk factor for stroke. The Framingham Study. JAMA. 1988;259(7):1025-1029. DOI: 10.1001/jama.1988.03720070025028

57. Rothwell PM, Eliasziw M, Gutnikov SA, et al. Endarterectomy for symptomatic carotid stenosis in relation to clinical subgroups and timing of surgery. Lancet. 2004;363(9413):915-924. DOI: 10.1016/S0140-6736(04)15785-1

58. Brott TG, Hobson RW 2nd, Howard G, et al. Stenting versus endarterectomy for treatment of carotid-artery stenosis (CREST). N Engl J Med. 2010;363(1):11-23. DOI: 10.1056/NEJMoa0912321

59. Bond R, Rerkasem K, Rothwell PM. Systematic review of the risks of carotid endarterectomy in relation to the clinical indication for and timing of surgery. Stroke. 2003;34(9):2290-2301. DOI: 10.1161/01.STR.0000087785.18566.1A

60. O'Brien JT, Thomas A. Vascular dementia. Lancet. 2015;386(10004):1698-1706. DOI: 10.1016/S0140-6736(15)00463-8

61. Royal College of Physicians. National clinical guideline for stroke, 5th edition. 2016. Available at: https://www.strokeaudit.org/Guideline/Full-Guideline.aspx

62. Kleindorfer DO, Towfighi A, Chaturvedi S, et al. 2021 Guideline for the prevention of stroke in patients with stroke and transient ischemic attack: a guideline from the American Heart Association/American Stroke Association. Stroke. 2021;52(7):e364-e467. DOI: 10.1161/STR.0000000000000375

63. Berge E, Whiteley W, Audebert H, et al. European Stroke Organisation (ESO) guidelines on intravenous thrombolysis for acute ischaemic stroke. Eur Stroke J. 2021;6(1):I-LXII. DOI: 10.1177/2396987321989865

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13. Examination Focus

Common MRCP/Neurology Exam Scenarios

Scenario 1: Immediate Management of Suspected TIA

Question: A 68-year-old man presents to ED with a 20-minute episode of right arm weakness and slurred speech that has now completely resolved. He has a history of hypertension. What is the most appropriate immediate management?

Model Answer:

1. Give aspirin 300mg immediately (unless on anticoagulation or contraindicated).
2. Check blood glucose to exclude hypoglycaemia.
3. Perform 12-lead ECG to detect atrial fibrillation.
4. Urgent referral to TIA clinic for assessment within 24 hours.
5. MRI brain (DWI sequence) and carotid Doppler to be arranged urgently.
6. Do not admit unless crescendo TIA, ongoing symptoms, or patient on anticoagulation requiring imaging to exclude bleed.

Key Points:

• EXPRESS study: Immediate treatment reduces 90-day stroke risk by 80%.
• NICE NG128: All suspected TIAs should be seen within 24 hours.
• Aspirin 300mg is first-line acute antiplatelet.

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Scenario 2: Carotid Stenosis and Surgery Timing

Question: A 72-year-old woman had a TIA 5 days ago (left hand weakness for 10 minutes). Carotid Doppler shows 85% stenosis of the right internal carotid artery. She is on aspirin 300mg. What is the next step?

Model Answer:

1. Carotid endarterectomy (CEA) within 2 weeks of symptom onset (ideally within 1 week).
2. Stenosis 70-99% (NASCET criteria) has high benefit from CEA (NNT = 6 to prevent one stroke over 2 years).
3. Early surgery (within 2 weeks) maximally reduces stroke risk during the highest-risk period.
4. Continue aspirin perioperatively.
5. After CEA, start long-term clopidogrel 75mg + atorvastatin 80mg + BP control.

Key Points:

• NASCET trial: CEA highly beneficial for symptomatic 70-99% stenosis.
• Timing is critical: stroke risk highest in first 2 weeks.
• 100% occlusion is a contraindication to surgery (no flow to restore).

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Scenario 3: Amaurosis Fugax

Question: A 65-year-old man describes a 5-minute episode of painless loss of vision in his right eye, like "a curtain coming down." Examination is normal. What is the diagnosis and investigation?

Model Answer:

• Diagnosis: Amaurosis fugax (transient monocular vision loss) due to embolism to the right retinal or ophthalmic artery.
• Localisation: Indicates ipsilateral (right) internal carotid artery disease.
• Investigations:
  1. Urgent carotid Doppler of right ICA (within 24 hours).
  2. MRI brain (DWI) to assess for silent infarcts.
  3. ECG to detect AF.
  4. Fundoscopy: May see Hollenhorst plaque (cholesterol emboli) or retinal artery occlusion.
• Management: Aspirin 300mg immediately; consider CEA if 50-99% stenosis.

Key Points:

• Amaurosis fugax = retinal TIA.
• Urgent carotid imaging is mandatory (high-risk feature).
• Painless monocular vision loss; ipsilateral carotid pathology.

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Scenario 4: Atrial Fibrillation and Anticoagulation

Question: A 70-year-old woman with a TIA 2 days ago is found to be in atrial fibrillation on ECG. MRI brain shows no infarction. What anticoagulation strategy should you use?

Model Answer:

1. Start DOAC (e.g., apixaban 5mg BD or rivaroxaban 20mg OD) immediately, now that imaging has excluded haemorrhage and shown no large infarct.
2. Stop aspirin once anticoagulation is therapeutic (DOACs are therapeutic within hours).
3. Continue atorvastatin 80mg and optimize BP control.
4. Calculate CHA2DS2-VASc score (she scores ≥2 with TIA + age + female = at least 4, indicating high stroke risk without anticoagulation).
5. Assess bleeding risk (HAS-BLED score), but in most cases, benefit of anticoagulation outweighs bleeding risk in AF with TIA/stroke.

Key Points:

• AF is present in 10-20% of TIA patients.
• DOACs preferred over warfarin (non-inferior/superior efficacy, lower intracranial haemorrhage risk).
• Safe to start anticoagulation immediately if imaging shows no haemorrhage or large infarct.

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Scenario 5: Limb-Shaking TIA

Question: A 60-year-old man reports recurrent brief episodes of involuntary shaking of the left arm, lasting 30 seconds, triggered by standing up. He has been treated for epilepsy without benefit. What is the likely diagnosis?

Model Answer:

• Diagnosis: Limb-shaking TIA due to critical right carotid stenosis.
• Mechanism: Severe stenosis/occlusion causes hypoperfusion when BP drops (orthostatic stress). Involuntary movements are due to ischaemia of motor cortex/subcortical areas.
• Key Distinguishing Features:
  • Triggered by postural change (standing, exertion).
  • No post-ictal confusion (unlike seizure).
  • Focal (one limb, contralateral to stenosis).
  • Refractory to antiepileptic drugs.
• Investigations: Urgent carotid Doppler (will show high-grade stenosis or occlusion).
• Management: Carotid endarterectomy if 50-99% stenosis; often curative.

Key Points:

• Rare presentation; easily misdiagnosed as focal seizures.
• Think of limb-shaking TIA in patients with "seizures" triggered by standing.
• Responds to revascularization, not AEDs.

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Viva Questions and Model Answers

Q1: How do you differentiate TIA from migraine aura?

Answer:

• TIA: Sudden onset, negative symptoms (loss of power, numbness, vision loss), brief duration (less than 60 min), older age, vascular risk factors, no headache.
• Migraine aura: Gradual onset ("march" over 5-20 minutes), positive symptoms (scintillations, fortifications, tingling), followed by headache, younger age, history of migraine.

Q2: What is the modern tissue-based definition of TIA?

Answer:

• TIA is a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without acute infarction (DWI-negative MRI).
• The old time-based definition (less than 24 hours) is outdated; symptoms lasting > 60 minutes often show DWI positivity (stroke, not TIA).

Q3: What are the NASCET criteria for measuring carotid stenosis?

Answer:

• NASCET % stenosis = (1 - [diameter at stenosis / diameter of normal distal ICA]) × 100.
• 50-69%: Moderate benefit from CEA.
• 70-99%: High benefit from CEA (NNT = 6).
• 100%: Occlusion; CEA contraindicated.

Q4: When would you consider dual antiplatelet therapy (aspirin + clopidogrel) in TIA?

Answer:

• NICE does not routinely recommend DAPT for TIA.
• However, based on CHANCE and POINT trials, some centres use short-term DAPT (21 days) for high-risk TIA (ABCD2 ≥4, large artery stenosis, recurrent events) or minor stroke (NIHSS ≤3).
• Balance benefit (25-32% stroke reduction) against bleeding risk (increased major haemorrhage 0.5-0.9%).

Q5: Why must patients not drive for 1 month after TIA?

Answer:

• DVLA regulation: Group 1 (car) licence holders must not drive for 1 month after TIA.
• Rationale: Stroke risk highest in first 7-30 days; sudden recurrence while driving poses danger.
• Group 2 (HGV/bus): Must not drive for 1 year and inform DVLA.

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Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists and follow local guidelines.