concise notes on: Stroke vs Stroke Mimics ( most commons and important ones) What step by step history and physical exam , investigation findings to elicit in the emergency to rule out each one and treat each differentials accordingly and effectively In the emergency give relevant mnemonics wherever possible and necessary. According to my mrcp and fcps part 2 exam ( long cases) , and ER dealing
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stroke vs stroke mimics emergency diagnosis MRCP FCPS clinical features investigations 2024
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https://pmc.ncbi.nlm.nih.gov/articles/PMC7939567
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I now have rich, comprehensive material. Let me compile the full, exam-grade notes.
STROKE vs STROKE MIMICS: Complete Emergency Notes
For MRCP / FCPS Part 2 Long Cases & ER Management
QUICK ORIENTATION MNEMONIC
"MIMIC FACTS" = the 8 most important stroke mimics:
Migraine with aura | Intracranial mass (tumor/abscess) | Metabolic (hypoglycemia, hyperglycemia, HE, Wernicke) | Infection (septic encephalopathy, meningitis/encephalitis) | Conversion disorder / functional | Functional / psychiatric | Arterial dissection (mimic TIA) | Cerebral venous thrombosis | Todd's postictal paralysis / Seizure | Subdural hematoma / SAH
PART 1 - RECOGNISING ACUTE STROKE IN THE ER
FAST Screening (prehospital/triage)
Face droop | Arm drift | Speech abnormal | Time = call code stroke
Extended: BE-FAST = Balance, Eyes (sudden visual loss), Face, Arm, Speech, Time
History - Step by Step
Mnemonic: "STROKE NOW"
| Letter | What to Ask |
|---|---|
| S | Sudden onset? - Stroke is typically maximal at onset; embolic = instantaneous, thrombotic = stuttering/stepwise |
| T | Time of last seen well - The single most important question (tPA window 4.5h, thrombectomy 6-24h) |
| R | Risk factors - HTN, DM, AF, dyslipidemia, smoking, prior stroke/TIA, carotid disease, coagulopathy |
| O | Other symptoms? - Headache (SAH, CVT, dissection), vomiting (raised ICP, posterior stroke), fever (infection), chest pain (aortic dissection) |
| K | Known history - Prior epilepsy, migraine, tumour, depression, conversion disorder |
| E | Events leading up - Trauma (subdural), exertion (dissection), neck manipulation, recent surgery |
| N | Neurological baseline - Establishes deficits are new |
| O | On medications - Anticoagulants (INR, DOAC), antiepileptics, insulin, immunosuppressants |
| W | Witness account - Was there seizure activity? Tongue biting? Incontinence? LOC? |
Physical Examination - Step by Step
Mnemonic: "VITAL NEURO"
-
V - Vitals: BP (both arms - difference >20 suggests dissection), HR (irregular = AF), SpO2, temp (fever = sepsis/encephalitis mimic), BGL at bedside immediately
-
I - Inspect: LOC (GCS), tongue bite marks, incontinence (seizure), meningism (SAH/meningitis)
-
T - Targeted NIHSS (see below)
-
A - Atrial fibrillation check: Pulse irregularity, ECG strip
-
L - Laterality: True stroke is almost always unilateral cortical deficits; bilateral = metabolic/brainstem
-
N - NIHSS (11 domains): LOC, LOC questions, LOC commands, Gaze, Visual fields, Facial palsy, Motor arm (R+L), Motor leg (R+L), Limb ataxia, Sensory, Best language, Dysarthria, Extinction
- Score 0-42; >15 = severe; >25 = very severe
-
E - Eye examination: Gaze deviation (ipsilateral to lesion in MCA stroke; away from lesion in pontine hemorrhage), nystagmus (posterior circulation), fundoscopy (papilledema = mass/CVT)
-
U - Upper motor signs: Pronator drift (arm outstretched 45 degrees, 10 sec), Babinski, hyperreflexia, UMN facial palsy (spares forehead)
-
R - Romberg/Coordination: Finger-nose, heel-shin, gait (cerebellar stroke)
-
O - Other systems: Carotid bruit, cardiac murmur, peripheral emboli (endocarditis), skin lesions (vasculitis)
Stroke Syndromes (anatomical localisation)
| Territory | Classic Features |
|---|---|
| MCA (dominant) | Contralateral hemiplegia (arm > leg), hemisensory loss, aphasia (Broca's/Wernicke's), contralateral gaze deviation, homonymous hemianopia |
| MCA (non-dominant) | Contralateral hemiplegia, hemisensory loss, neglect, constructional apraxia |
| ACA | Contralateral leg > arm weakness, abulia, urinary incontinence, frontal release signs |
| PCA | Homonymous hemianopia, alexia without agraphia, memory disturbance, contralateral hemisensory loss |
| Vertebrobasilar/Posterior | "5 Ds": Dizziness, Diplopia, Dysarthria, Dysphagia, Drop attacks + crossed signs (ipsilateral cranial nerve palsy + contralateral hemiplegia) |
| Lacunar | Pure motor hemiplegia, pure sensory, sensorimotor, ataxic hemiparesis, clumsy hand-dysarthria |
Lacunar mnemonic "PPSA+C": Pure Motor, Pure Sensory, Sensorimotor, Ataxic hemiparesis, Clumsy hand-dysarthria
PART 2 - INVESTIGATIONS IN THE ER (Time-Critical)
"BLOOD SUGAR CT" = First 30 minutes
| Test | Purpose |
|---|---|
| Blood glucose | #1 priority - exclude hypoglycemia immediately |
| LFTs + electrolytes + U&E | Metabolic encephalopathy, hyponatremia |
| Oximetry + ABG | Hypoxia, CO poisoning |
| Osmolality + ammonia | Hyperosmolar state, hepatic encephalopathy |
| Diphtheria/Toxin screen | Only if suspected |
| Septix screen: FBC, CRP, cultures, lactate | Septic encephalopathy, endocarditis |
| Urine dip | UTI as metabolic precipitant in elderly |
| Glucose (repeat) | |
| APT / INR / platelet count | Coagulopathy, thrombolysis eligibility |
| Renal (creatinine) + TFTs | |
| CT brain without contrast | FIRST imaging: excludes hemorrhage, mass |
| Troponin + ECG | AF, MI triggering stroke |
CT Brain Interpretation (Non-contrast)
Ischemic stroke signs (early, within 3-6h):
- Hyperdense MCA sign (clot in vessel)
- Loss of grey-white differentiation (lenticular nucleus, insular ribbon)
- Sulcal effacement
ASPECTS score (for MCA territory): 10 = normal, score ≥6 = suitable for thrombolysis/thrombectomy
Hemorrhagic stroke: Hyperdense area (white on CT)
When to do MRI DWI?
- Within 4.5h window to confirm ischemic stroke when CT normal but high suspicion
- Posterior fossa / brainstem events (CT insensitive)
- DWI bright + ADC dark = acute ischemic infarct (water diffusion restricted)
PART 3 - STROKE MIMICS (The Critical Differentials)
Overview
20-50% of "code stroke" activations are ultimately NOT strokes. Distinguishing them matters enormously - thrombolysing a mimic can be harmful; missing a true stroke is catastrophic.
Red flags AGAINST stroke (favoring mimic):
- Age <50 without vascular risk factors
- LOC/syncope at onset (unusual for stroke)
- Gradual onset (not sudden maximal deficit)
- Normal BGL + normal CT yet atypical deficit
- History of epilepsy, migraine, psychiatric disease
- Symptoms fluctuate and improve without treatment
- Positive symptoms (visual sparkles, paraesthesias radiating = migraine) vs. negative (loss of function = stroke)
- No gaze deviation despite severe apparent hemiplegia
- "Arm drift without pronation" (functional)
MIMIC 1: HYPOGLYCEMIA ⭐⭐⭐ (Most Common Reversible Mimic)
Features: Focal neurological deficits (hemiplegia, aphasia) + BGL <3.0 mmol/L. Can mimic stroke for hours-days.
| Step | Action |
|---|---|
| History | Diabetic on insulin/sulphonylurea, skipped meal, vomiting, alcohol |
| Exam | Sweating, tachycardia, focal neuro signs, GCS depression |
| Investigation | Bedside BGL immediately. If BGL <3.0 mmol/L, treat before imaging |
| Treatment | IV dextrose 50 mL of 50% (or 150 mL of 10%) glucose; recheck BGL every 15 min |
| Caveat | If deficit persists after correction of BGL, consider concurrent true stroke |
Rule: Check glucose BEFORE everything else - it takes 10 seconds and can save a thrombolysis.
MIMIC 2: TODD'S PARALYSIS / SEIZURE ⭐⭐⭐
Features: Focal motor weakness (hemiplegia, aphasia) following a seizure. Lasts minutes to hours (occasionally 24-48h).
| Step | Action |
|---|---|
| History | Witnessed convulsions, tongue biting, incontinence, known epilepsy, postictal confusion; prior stroke focus can generate seizures |
| Exam | Flaccid weakness that is resolving over time; normal or only mildly abnormal neuro exam; drowsiness disproportionate to deficits |
| Investigation | EEG if suspected; CT to exclude structural cause; glucose; LP if meningitis suspected |
| Treatment | Benzodiazepine (lorazepam IV 4mg) for active seizure; anti-epileptic loading if indicated; treat precipitant |
| Caveat | Seizure can occur at onset of true stroke - always image if deficit persists |
Clue: "Symptoms improving over time" = Todd's; "Symptoms maximal at onset and stable/worsening" = stroke.
MIMIC 3: MIGRAINE WITH AURA (Hemiplegic Migraine) ⭐⭐
Features: Focal neuro deficits (visual aura, sensorimotor, speech) + headache (may be absent in "acephalgic migraine").
| Step | Action |
|---|---|
| History | Previous identical episodes, young patient, female, family history of hemiplegic migraine, triggers (stress, menses, cheese), positive sensory phenomena (sparkles, spreading tingling - "march") |
| Exam | Aura that migrates or "marches" (unlike stroke which is maximal at onset), headache phase follows aura |
| Investigation | CT normal; MRI may show cortical spreading depression or transient perfusion reduction. DWI occasionally positive (reversible) |
| Treatment | Avoid triptans in hemiplegic migraine (vasoconstriction risk). IV fluids, antiemetics (metoclopramide 10mg IV), analgesia (paracetamol, NSAIDs), dark quiet room |
| Caveat | 15% of strokes in patients <45 years are migraine-related. Exclude by imaging. |
Clue: "Positive symptoms, gradual spread, march across body, history of similar episodes = migraine." Negative focal deficit maximal at onset = stroke.
MIMIC 4: BRAIN TUMOUR / ABSCESS / SUBDURAL ⭐⭐
Features: Gradual progressive deficit, but may present acutely (hemorrhage into tumour, or rapid edema).
| Step | Action |
|---|---|
| History | Weeks-months of progressive headache, cognitive decline, focal weakness; fever + immunocompromised (abscess); head trauma + elderly/alcoholic/anticoagulated (subdural) |
| Exam | Papilledema (raised ICP), bilateral neurological signs, altered cognition, fever (abscess), scalp/skull tenderness |
| Investigation | CT brain (may show ring-enhancing lesion, midline shift, surrounding edema, hypodense subdural collection); LP CONTRAINDICATED if raised ICP; MRI with gadolinium |
| Treatment | Dexamethasone 10mg IV (cerebral edema); Neurosurgical referral; Broad-spectrum antibiotics + antifungals (abscess); Surgical drainage (subdural); Do NOT give tPA |
Subdural clue: Crescent-shaped hypodense (chronic) or hyperdense (acute) collection following brain contour on CT.
MIMIC 5: METABOLIC ENCEPHALOPATHY ⭐⭐ (Wernicke, HE, Hyponatremia)
Wernicke Encephalopathy:
- Triad: "COA" = Confusion + Ophthalmoplegia + Ataxia (only all 3 in 10-30%)
- History: Alcoholism, malnutrition, hyperemesis, bariatric surgery
- CT often normal; MRI: mamillary body/periaqueductal changes
- Treatment: Thiamine 500mg IV TDS x 2 days BEFORE any glucose (glucose precipitates Wernicke)
Hepatic Encephalopathy:
- History: Liver disease, precipitant (infection, GIB, constipation, diuretics, TIPSS)
- Exam: Jaundice, asterixis, fetor hepaticus, altered consciousness - NOT focal
- NH3 level elevated; EEG triphasic waves
- Treatment: Lactulose, rifaximin, treat precipitant
Hyponatremia (Na <125):
- Focal or diffuse neuro signs; Na on U&E
- Correct slowly: 0.5-1 mmol/L/h (avoid central pontine myelinolysis)
MIMIC 6: HYPERTENSIVE ENCEPHALOPATHY ⭐⭐
Features: Severe BP (>180/120) + confusion + headache + visual disturbance (PRES). Focal deficits rare - diffuse more common.
| Step | Action |
|---|---|
| History | Known hypertension, non-compliance with medications, eclampsia |
| Exam | BP markedly elevated, papilledema, retinal changes, NO dense focal deficit |
| Investigation | MRI FLAIR: posterior white matter hyperintensity (occipital/parietal = PRES); CT often normal |
| Treatment | Gradual BP lowering: aim 25% reduction over first hour with IV labetalol or nicardipine. DO NOT drop BP rapidly in true stroke (may extend infarct) |
Key distinction: In true stroke, rapidly lowering BP is harmful (unless >220/120 without thrombolysis). In hypertensive encephalopathy/PRES, lowering BP is the treatment.
MIMIC 7: MENINGITIS / ENCEPHALITIS / CEREBRAL ABSCESS ⭐⭐
Features: Fever + focal neuro signs + meningism.
| Step | Action |
|---|---|
| History | Fever, neck stiffness, photophobia, rash (meningococcal), HSV exposure, immunocompromised status |
| Exam | Kernig's sign, Brudzinski's sign, petechial/purpuric rash, photophobia |
| Investigation | CT before LP (exclude raised ICP/mass). LP: opening pressure, cells, protein, glucose (CSF:serum ratio <0.5 = bacterial), Gram stain, culture, HSV PCR, India ink |
| Treatment | Do NOT delay antibiotics while awaiting CT. Ceftriaxone 2g IV + Dexamethasone 10mg IV immediately; add Aciclovir 10mg/kg IV if HSV encephalitis suspected |
"Don't delay antibiotics for LP" - especially in meningococcal meningitis (mortality rises per hour).
MIMIC 8: FUNCTIONAL NEUROLOGICAL DISORDER (Conversion) ⭐
Features: Motor weakness, sensory loss, speech change without anatomical basis.
| Clue | Functional Finding |
|---|---|
| Hoover's sign | Hip extension weakness "converts" to normal when contralateral hip is flexed against resistance |
| Arm drift | Falls without pronation (stroke droops AND pronates) |
| Tubular vision | Field defects that don't conform to visual anatomy |
| La belle indifference | Apparent lack of concern about deficits |
| Inconsistency | Deficits vary, improve with distraction |
| Gaze | Follows examiner with eyes even with "gaze deviation" |
Investigation: Normal CT/MRI; Normal EEG; All bloods normal.
Treatment: Reassurance, neuropsychiatric referral, avoid unnecessary thrombolysis.
MIMIC 9: CEREBRAL VENOUS THROMBOSIS (CVT) ⭐⭐
Features: Headache (can be thunderclap) + focal deficit + seizure + raised ICP. Often young women on OCP.
| Step | Action |
|---|---|
| History | Young female, OCP, pregnancy/puerperium, dehydration, thrombophilia, malignancy |
| Exam | Papilledema, focal or bilateral deficits, seizure |
| CT | May be normal; "Dense sinus sign" (hyperdense superior sagittal sinus); "Empty delta sign" (filling defect in sinus after contrast) |
| Investigation | MRV (MR venography) = gold standard |
| Treatment | Anticoagulation (LMWH or heparin) even if hemorrhagic infarct present - reverses the venous thrombosis. Anticonvulsants if seizures. |
MIMIC 10: AORTIC DISSECTION ⭐ (Do NOT thrombolyse)
Features: Severe tearing chest/back pain + focal neuro deficit (carotid or vertebral artery origin involvement).
| Key Point | Detail |
|---|---|
| History | Hypertension, Marfan's, trauma, cocaine use |
| Exam | BP difference >20mmHg between arms, aortic regurgitation murmur, absent pulses |
| Investigation | CXR (wide mediastinum), CT aortogram |
| Treatment | Emergency cardiothoracic surgery. tPA is ABSOLUTELY CONTRAINDICATED |
PART 4 - THE ER MANAGEMENT ALGORITHM (True Stroke)
Time Targets ("D2N" = Door to Needle)
| Target | Time |
|---|---|
| Door to doctor | 10 min |
| Door to CT completion | 25 min |
| Door to CT read | 45 min |
| Door to needle (tPA) | 60 min |
| Neurology expertise available | 15 min |
IV tPA (Alteplase) Protocol
Indication: Ischemic stroke, last known well within 4.5 hours, no contraindications
Dose: 0.9 mg/kg IV (max 90 mg); 10% as bolus over 1 min, remainder over 60 min
Alternatives: Tenecteplase 0.25 mg/kg IV single bolus (max 25 mg) - simpler, non-inferior
Key Contraindications mnemonic "BALD HEAD":
Bleeding (active / history of intracranial hemorrhage) | Anticoagulated (INR >1.7 or DOAC within 48h) | Low platelets <100,000 | Dissection (aortic) | Hemorrhage on CT | Extreme hypertension (BP >185/110 at time of treatment) | Abdominal/Retroperitoneal surgery within 14 days | Door-to-needle >4.5h
BP threshold before tPA: Must be <185/110; treat with labetalol 10-20mg IV or nicardipine infusion
Endovascular Thrombectomy (EVT)
- Indication: Large vessel occlusion (ICA, proximal MCA M1), NIHSS ≥6, ASPECTS ≥6, within 6h (up to 24h with penumbra imaging)
- Get CT Angiography (CTA) head and neck for all thrombolysis candidates
BP Management (Ischemic Stroke, No Thrombolysis)
- Do NOT treat unless BP >220/120 or specific indication (MI, aortic dissection, hypertensive encephalopathy)
- Reason: Autoregulation lost - brain depends on perfusion pressure
Hemorrhagic Stroke Management
ICH Score (predicts 30-day mortality):
- GCS 3-4 = 2 pts; GCS 5-12 = 1 pt; GCS 13-15 = 0 pt
- ICH volume >30mL = 1 pt; Intraventricular blood = 1 pt; Infratentorial location = 1 pt; Age >80 = 1 pt
- Score 0 = 0% mortality; Score 5-6 = 100% mortality
Management:
- Reverse anticoagulation immediately (Vit K + PCC for warfarin; specific reversal agents for DOACs)
- Lower BP to <140mmHg (IV labetalol/nicardipine) - reduces hematoma expansion
- Neurosurgery referral (hydrocephalus, large/accessible hematoma, cerebellar bleed >3cm)
- No tPA, no aspirin acutely
PART 5 - COMPARISON TABLE: Stroke vs Top Mimics
| Feature | True Stroke | Hypoglycemia | Todd's Palsy | Migraine | Tumour/SDH | CVT | Conversion |
|---|---|---|---|---|---|---|---|
| Onset | Sudden, maximal | Sudden | Post-ictal | Gradual (aura), then headache | Gradual (weeks) | Gradual-subacute | Variable |
| Headache | Uncommon (unless SAH/ICH) | Rare | Rare | Hallmark | Yes (raised ICP) | Severe | Rare |
| Fever | No | No | No | No | Yes (abscess) | No | No |
| LOC | Rare | Yes (severe) | Yes (postictal) | Rare | Late | Late | May mimic |
| BGL | Normal | Low | Normal | Normal | Normal | Normal | Normal |
| CT | +/- hyperdense artery or ischemia | Normal | Normal | Normal | Mass / ring-enhancing | Normal or sinus sign | Normal |
| Key test | CT/MRI DWI | BGL | EEG / time | MRI | CT/MRI Gad | MRV | Clinical exam |
| tPA | YES (if eligible) | NO | NO | NO | NO | NO | NO |
PART 6 - HIGH-YIELD EXAM MNEMONICS SUMMARY
| Mnemonic | Meaning |
|---|---|
| BE-FAST | Balance, Eyes, Face, Arm, Speech, Time |
| STROKE NOW | History pillars: Sudden, Time, Risk factors, Other symptoms, Known hx, Events, Neuro baseline, On medications, Witnessed |
| VITAL NEURO | Exam structure in ER |
| BLOOD SUGAR CT | First ER investigations |
| MIMIC FACTS | 8 key mimics |
| PPSA+C | Lacunar syndromes |
| COA | Wernicke triad |
| BALD HEAD | tPA contraindications |
| "Positive symptoms = Mimic" | Migraine/conversion have positive (extra) symptoms; stroke causes loss (negative symptoms) |
| "Time is Brain" | 1.9 million neurons die per minute of untreated stroke |
PART 7 - EXAM LONG CASE APPROACH (MRCP/FCPS)
Presenting a Stroke Mimic Case:
-
"This patient presented with sudden focal neurological deficit suggesting a stroke syndrome. However, several features suggest a possible stroke mimic..."
-
Then systematically address:
- Onset (gradual vs. sudden)
- Age and vascular risk profile
- Preceding history (epilepsy, migraine, DM, liver disease, malignancy)
- Exam findings inconsistent with anatomy (bilateral, fluctuating, Hoover positive)
- Bedside glucose result
- CT findings
-
Management approach:
- "I would stabilise the patient (ABC), check BGL, establish IV access, and perform CT brain as priority"
- "If BGL <3.0, treat hypoglycemia first and reassess"
- "If CT shows no hemorrhage and within 4.5h, proceed with thrombolysis workup"
- "If any features suggesting mimic (post-ictal state, metabolic cause, raised ICP on CT), withhold tPA"
Sources: Rosen's Emergency Medicine (9780323757898), Goldman-Cecil Medicine (9780323930345), Plum & Posner (9780190208875), Adams & Victor's Neurology (9781264264520); PMC stroke mimics review; EMOttawa: Identifying stroke mimics
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