Clinical Approach to Sudden Focal Neurologic Deficit
Comprehensive Practical Framework1. Symptom Overview
Understanding the clinical significance and classification of sudden focal neurologic deficit
Sudden focal neurologic deficit represents one of the most time-critical presentations in medicine. Stroke affects approximately 795,000 people annually in the United States, making it the fifth leading cause of death and the leading cause of long-term disability. Globally, stroke accounts for approximately 11% of all deaths. Every minute of untreated large vessel occlusion results in the loss of approximately 1.9 million neurons, underscoring the urgency of the “time is brain” principle. Approximately 87% of strokes are ischemic, while 13% are hemorrhagic, but the clinical presentation of sudden focal neurologic deficit extends beyond stroke to include stroke mimics, which account for up to 30% of initial stroke alerts.
Definition
A sudden focal neurologic deficit is the acute onset of neurological symptoms or signs that can be localized to a specific region of the central nervous system. This includes motor weakness, sensory loss, visual disturbances, speech abnormalities, or coordination deficits that develop within seconds to minutes and reflect dysfunction of a discrete neuroanatomical structure or vascular territory.
Classification by Duration
| Category | Duration | Common Causes | Clinical Significance |
|---|---|---|---|
| Transient (Transient Ischemic Attack) | Typically less than 1 hour; by definition, no infarction on imaging | Thromboembolism, large vessel stenosis, cardioembolic source | High short-term stroke risk (up to 10-15% at 90 days without treatment); urgent evaluation required |
| Acute Stroke | Persistent deficit with confirmed infarction or hemorrhage | Large vessel occlusion, small vessel disease, cardioembolism, intracerebral hemorrhage | Time-critical emergency; thrombolysis window up to 4.5 hours, thrombectomy up to 24 hours in select patients |
| Stroke Mimic | Variable; may be transient or persistent | Seizure with postictal paralysis, migraine with aura, hypoglycemia, functional disorder | Accounts for 20-30% of stroke alerts; requires careful differentiation to avoid unnecessary thrombolysis |
Classification by Mechanism
Ischemic (87% of strokes)
Large vessel atherosclerosis: Approximately 15-20% of ischemic strokes; involves carotid or intracranial stenosis with artery-to-artery embolism or hypoperfusion.
Cardioembolism: Approximately 20-30%; atrial fibrillation is the most common source, followed by valvular disease, recent myocardial infarction, and patent foramen ovale.
Small vessel occlusion (lacunar): Approximately 20-25%; affects penetrating arteries, associated with hypertension and diabetes.
Other determined cause: Approximately 5%; includes dissection, vasculitis, hypercoagulable states, and moyamoya disease.
Cryptogenic: Approximately 25-30%; no identified cause despite complete workup.
Hemorrhagic (13% of strokes)
Intracerebral hemorrhage: Approximately 10% of all strokes; most commonly from hypertensive arteriopathy affecting deep structures (basal ganglia, thalamus, pons, cerebellum) or cerebral amyloid angiopathy affecting lobar regions.
Subarachnoid hemorrhage: Approximately 3% of all strokes; most commonly from ruptured saccular aneurysm; presents with sudden severe headache (“thunderclap”) often with focal deficits.
Key distinction: Cannot reliably differentiate ischemic from hemorrhagic stroke clinically; neuroimaging is mandatory before treatment decisions.
Classification by Vascular Territory
| Vascular Territory | Typical Deficits | Classic Syndromes |
|---|---|---|
| Anterior Cerebral Artery | Contralateral leg weakness greater than arm, abulia, urinary incontinence, alien hand syndrome | Medial frontal syndrome |
| Middle Cerebral Artery | Contralateral face and arm weakness greater than leg, hemisensory loss, homonymous hemianopia, aphasia (dominant) or neglect (non-dominant) | Most common stroke territory; malignant MCA syndrome in large infarcts |
| Posterior Cerebral Artery | Homonymous hemianopia with macular sparing, visual agnosia, memory impairment, alexia without agraphia (dominant) | Anton syndrome (cortical blindness with denial) |
| Vertebrobasilar System | Vertigo, diplopia, dysarthria, dysphagia, ataxia, crossed deficits (ipsilateral cranial nerve, contralateral body) | Wallenberg syndrome (lateral medullary), locked-in syndrome (basilar), top of the basilar syndrome |
| Lacunar (Small Vessel) | Pure motor hemiparesis, pure sensory stroke, ataxic hemiparesis, dysarthria-clumsy hand syndrome | Classically no cortical signs (no aphasia, neglect, or visual field cut) |
Classification by Onset Pattern
| Pattern | Description | Suggests |
|---|---|---|
| Sudden maximal onset | Deficit is maximal at onset with no progression | Embolic stroke (cardiogenic or artery-to-artery), hemorrhage |
| Stuttering or fluctuating | Waxing and waning symptoms over minutes to hours | Large vessel stenosis with hypoperfusion, growing thrombus |
| Stepwise progression | Distinct episodes of worsening with stable periods between | Recurrent embolism, propagating thrombus |
| Gradual progression | Steadily worsening over hours | Expanding hemorrhage, cerebral edema, stroke in evolution |
| Wake-up stroke | Patient awakens with deficit; last known well is bedtime | Time of onset unknown; may still be candidate for intervention based on imaging |
Key Concept: “Time Is Brain”
In acute ischemic stroke with large vessel occlusion, approximately 1.9 million neurons, 14 billion synapses, and 12 kilometers of myelinated fibers are lost per minute of untreated ischemia. This translates to the brain aging 3.6 years for every hour of untreated stroke. The treatment windows are: intravenous thrombolysis (alteplase or tenecteplase) up to 4.5 hours from last known well in eligible patients, and mechanical thrombectomy up to 24 hours in select patients with favorable imaging profiles.
2. Pathophysiology and Mechanisms
Understanding the underlying mechanisms of sudden focal neurologic deficit
Understanding the pathophysiology of sudden focal neurologic deficit requires knowledge of cerebral blood flow regulation, the ischemic cascade, and the concept of the ischemic penumbra. The brain, despite comprising only 2% of body weight, receives approximately 15% of cardiac output and consumes 20% of total body oxygen. Normal cerebral blood flow is approximately 50-55 mL per 100 grams of brain tissue per minute. When blood flow falls below critical thresholds, a predictable sequence of cellular dysfunction and death occurs.
The Ischemic Cascade
| Stage | Cerebral Blood Flow | Cellular Events | Clinical Correlation |
|---|---|---|---|
| Normal perfusion | 50-55 mL/100g/min | Normal neuronal function and metabolism | No symptoms |
| Oligemia | 22-50 mL/100g/min | Compensatory increase in oxygen extraction fraction; protein synthesis suppressed | May be asymptomatic; represents at-risk tissue |
| Ischemic penumbra | 12-22 mL/100g/min | Electrical failure; neurons cease firing but remain structurally intact; potentially salvageable | Clinical deficit present; this is the target of reperfusion therapy |
| Infarct core | Less than 10-12 mL/100g/min | Membrane failure; irreversible cell death within minutes; excitotoxicity, oxidative stress, inflammation | Irreversible deficit; not salvageable even with reperfusion |
Mechanisms of Ischemic Stroke
Large Vessel Atherosclerosis
Location: Extracranial carotid bifurcation, intracranial large arteries (middle cerebral artery M1, basilar artery)
Mechanism: Plaque rupture with artery-to-artery thromboembolism; in-situ thrombosis; or hypoperfusion from critical stenosis
Clinical relevance: Often preceded by transient ischemic attacks; may benefit from carotid revascularization
Cardioembolism
Sources: Atrial fibrillation (most common), mechanical valves, recent myocardial infarction with mural thrombus, infective endocarditis, patent foramen ovale with venous thrombus
Mechanism: Cardiac thrombus dislodges and travels to cerebral circulation; typically lodges at branch points
Clinical relevance: Often maximal at onset; higher risk of hemorrhagic transformation; requires anticoagulation for secondary prevention
Small Vessel Disease (Lacunar)
Location: Penetrating arteries to basal ganglia, thalamus, internal capsule, pons, corona radiata
Mechanism: Lipohyalinosis and microatheroma from chronic hypertension and diabetes; vessel wall thickening with luminal narrowing
Clinical relevance: Classic lacunar syndromes; absence of cortical signs; best prevention is blood pressure control
Mechanisms of Hemorrhagic Stroke
| Type | Typical Location | Mechanism | Risk Factors |
|---|---|---|---|
| Hypertensive intracerebral hemorrhage | Deep structures: putamen (35-50%), thalamus (10-15%), pons (5-10%), cerebellum (5-10%) | Chronic hypertension causes lipohyalinosis and Charcot-Bouchard microaneurysms in small penetrating arteries; rupture leads to parenchymal hemorrhage | Chronic poorly controlled hypertension, especially with acute spikes |
| Cerebral amyloid angiopathy | Lobar (cortical-subcortical); often occipital or parietal | Beta-amyloid deposition weakens walls of small and medium cortical vessels; leads to recurrent lobar hemorrhages | Age greater than 65, dementia, prior lobar hemorrhage, APOE ε4 allele |
| Aneurysmal subarachnoid hemorrhage | Subarachnoid space; most common at anterior communicating artery, posterior communicating artery, middle cerebral artery bifurcation | Saccular aneurysm at vessel bifurcation ruptures; blood enters subarachnoid space; may cause vasospasm and delayed cerebral ischemia | Smoking, hypertension, family history, polycystic kidney disease, connective tissue disorders |
| Hemorrhagic transformation of ischemic stroke | Within territory of ischemic infarct | Reperfusion of infarcted tissue leads to bleeding through damaged blood-brain barrier; ranges from petechial to parenchymal hematoma | Large infarct size, thrombolysis, anticoagulation, hyperglycemia |
The Ischemic Penumbra: Target of Acute Therapy
Core Concept: The ischemic penumbra is functionally impaired but structurally intact brain tissue surrounding the irreversibly damaged infarct core. This tissue is the target of all acute stroke therapies.
- Time dependency: The penumbra progressively converts to infarct over time; without reperfusion, most penumbra becomes core within 6-24 hours
- Collateral circulation: Patients with good collateral blood supply maintain larger penumbras for longer; this is why some patients benefit from thrombectomy up to 24 hours
- Imaging identification: Perfusion imaging (CT perfusion or MR perfusion) can identify penumbra as the “mismatch” between the area of low blood flow (at risk) and the area of irreversible damage (core)
How Conditions Cause Sudden Focal Neurologic Deficit
| Condition | Mechanism | Treatment Implication |
|---|---|---|
| Atrial fibrillation with cardioembolism | Stasis in left atrial appendage leads to thrombus formation; embolization to cerebral vessels causes sudden occlusion | Acute: reperfusion therapy if eligible. Secondary prevention: oral anticoagulation, not antiplatelet alone |
| Carotid artery dissection | Intimal tear creates false lumen; can cause thromboembolism from exposed subendothelium or hemodynamic compromise from stenosis | Antithrombotic therapy (antiplatelet or anticoagulation); endovascular intervention rarely needed |
| Seizure with postictal (Todd’s) paralysis | Neuronal exhaustion and cortical inhibition following seizure activity; causes transient focal weakness lasting minutes to hours | Not a stroke; treatment directed at underlying seizure disorder; avoid unnecessary thrombolysis |
| Hypoglycemia | Glucose is primary neuronal fuel; hypoglycemia causes focal neurological dysfunction mimicking stroke, often with hemiparesis | Check fingerstick glucose immediately in all stroke alerts; symptoms resolve rapidly with glucose correction |
| Migraine with aura (hemiplegic migraine) | Cortical spreading depression causes transient neurological symptoms; typically visual followed by sensory then motor symptoms over 20-60 minutes | Gradual “march” of symptoms distinguishes from stroke; history of similar events; avoid unnecessary thrombolysis |
| Intracerebral hemorrhage | Vessel rupture leads to parenchymal hematoma; direct tissue destruction plus mass effect and elevated intracranial pressure | Thrombolysis absolutely contraindicated; requires blood pressure management, reversal of anticoagulation, consideration of surgical evacuation |
Often Overlooked Mechanism: Paradoxical Embolism
In patients with cryptogenic stroke, particularly those under age 60, patent foramen ovale (present in approximately 25% of the population) may allow venous thrombus to cross to the arterial circulation, bypassing the pulmonary filter. Key features suggesting paradoxical embolism include: stroke upon waking or after Valsalva maneuver (straining, coughing), recent prolonged immobility or travel, presence of deep vein thrombosis, and cortical infarct pattern without other identified source. In selected patients, patent foramen ovale closure significantly reduces recurrent stroke risk.
Cerebral Autoregulation and Its Failure
Normal Autoregulation
Cerebral blood flow is maintained constant across a wide range of mean arterial pressures (approximately 60-150 mmHg) through arteriolar vasoconstriction and vasodilation. This protects the brain from both hypoperfusion and hyperperfusion.
Impaired Autoregulation in Stroke
In acute stroke, autoregulation is impaired in ischemic tissue. Blood flow becomes passively dependent on blood pressure. This is why aggressive blood pressure lowering is avoided in acute ischemic stroke (except before thrombolysis) — it may worsen penumbral perfusion. Conversely, in hemorrhagic stroke, elevated blood pressure worsens bleeding.
3. History Taking
A comprehensive approach to eliciting the history in sudden focal neurologic deficit
Red Flags — Require Emergent Evaluation
- Sudden severe headache (“thunderclap”) — Subarachnoid hemorrhage until proven otherwise
- Decreased level of consciousness — Large hemispheric stroke, brainstem involvement, or elevated intracranial pressure
- Neck pain with focal deficit — Cervical artery dissection
- Recent head or neck trauma — Traumatic dissection or traumatic intracranial hemorrhage
- Known anticoagulant use — Higher risk of hemorrhagic stroke; affects treatment decisions
- Recent surgery or invasive procedure — May contraindicate thrombolysis
- Symptoms in a young patient (under 50) — Consider dissection, paradoxical embolism, hypercoagulable state, vasculitis
- Fever with focal deficit — Infective endocarditis with septic embolism, meningitis, brain abscess
The Most Important Question: “When was the patient last known to be at their neurological baseline?”
This establishes the “last known well” (LKW) time, which determines eligibility for time-sensitive treatments. Do not accept “when symptoms started” — you need the last time the patient was definitely normal. For wake-up strokes, LKW is when the patient went to sleep. Document this time precisely (hour and minute if possible).
Systematic History: The “STROKE” Approach
Use the mnemonic “STROKE” to ensure comprehensive history taking:
- S — Sudden onset and Sequence: Was onset truly sudden (seconds) or gradual? Did symptoms start together or in sequence? What was the patient doing at onset?
- T — Time of last known well: The critical question for treatment eligibility. Not “when did symptoms start” but “when was the patient last definitely normal?”
- R — Risk factors and Recent events: Vascular risk factors (hypertension, diabetes, smoking, atrial fibrillation); recent procedures, trauma, or illness
- O — Other symptoms: Headache, neck pain, seizure activity, chest pain, palpitations, fever, recent infections
- K — Known medical history: Prior stroke or transient ischemic attack, cardiac disease, bleeding history, cancer, hypercoagulable states
- E — Exclusions for thrombolysis: Recent surgery, active bleeding, known intracranial pathology, current anticoagulation, severe uncontrolled hypertension
Targeted Questions by Suspected Cause
| Suspected Cause | Key Features | Ask This Question |
|---|---|---|
| Cardioembolic stroke (atrial fibrillation) | Sudden maximal deficit, cortical involvement, history of palpitations | “Have you ever been told you have an irregular heartbeat? Do you ever feel your heart racing or fluttering?” |
| Large vessel atherosclerosis | Preceding transient ischemic attacks (especially stereotyped), known carotid disease | “Have you had any brief episodes of weakness, numbness, or vision loss in recent weeks that resolved on their own?” |
| Cervical artery dissection | Neck pain, recent trauma or chiropractic manipulation, younger patient | “Have you had any neck pain or headache? Any recent injury to your head or neck, even minor? Any chiropractic treatments?” |
| Subarachnoid hemorrhage | Thunderclap headache, neck stiffness, brief loss of consciousness at onset | “Did you have a sudden severe headache — the worst of your life — at the moment this started?” |
| Intracerebral hemorrhage | Headache, vomiting, progressive deterioration, severe hypertension | “Did you have a headache or vomiting when this started? Have symptoms gotten worse since they began?” |
| Seizure with postictal (Todd’s) paralysis | Witnessed convulsive activity, tongue bite, incontinence, gradual improvement | “Did anyone witness shaking or jerking movements? Any tongue biting or loss of bladder control? Are symptoms improving?” |
| Hypoglycemia | Diabetic on insulin or sulfonylureas, missed meal, confusion with focal signs | “Do you have diabetes? Did you take your insulin or diabetes medication? When did you last eat?” |
| Migraine with aura (hemiplegic migraine) | History of similar episodes, gradual march of symptoms, younger patient, subsequent headache | “Have you ever had similar episodes before that resolved? Do you get migraines? Did symptoms spread gradually over minutes?” |
| Infective endocarditis | Fever, new murmur, risk factors (intravenous drug use, prosthetic valve, recent dental procedure) | “Have you had fevers, chills, or night sweats? Do you use intravenous drugs? Have you had any dental work recently?” |
| Paradoxical embolism (patent foramen ovale) | Younger patient, cryptogenic stroke, Valsalva at onset, recent immobility | “Were you straining, coughing, or bearing down when this started? Have you had recent prolonged travel or bed rest? Any history of blood clots in your legs?” |
Essential Questions for Thrombolysis Eligibility
Screen for Contraindications
Ask specifically about each of the following — these affect thrombolysis eligibility:
- Recent major surgery or serious trauma (within 14 days)
- Recent gastrointestinal or urinary tract bleeding (within 21 days)
- Recent lumbar puncture, arterial puncture at non-compressible site
- Current use of anticoagulants (name, dose, last taken)
- History of intracranial hemorrhage at any time
- Known brain tumor, arteriovenous malformation, or aneurysm
- Recent stroke (within 3 months)
- Recent myocardial infarction (within 3 months)
- Pregnancy or recent delivery
- Known bleeding disorder or very low platelet count
Medication and Social History
Critical Medications to Document
- Anticoagulants — Warfarin (check INR), direct oral anticoagulants (apixaban, rivaroxaban, dabigatran, edoxaban) — dose and time of last intake
- Antiplatelet agents — Aspirin, clopidogrel, ticagrelor, prasugrel
- Antihypertensives — Type and compliance; recent changes
- Insulin and oral hypoglycemics — Type, dose, timing
- Oral contraceptives or hormone replacement — Thrombotic risk
- Recreational drugs — Cocaine and amphetamines cause vasoconstriction and hemorrhage; intravenous drug use raises concern for endocarditis
Social and Occupational History
- Smoking: Current or past; quantify pack-years; major modifiable risk factor
- Alcohol: Heavy use increases hemorrhagic stroke risk and atrial fibrillation
- Illicit drug use: Cocaine causes both ischemic and hemorrhagic stroke; intravenous drug use raises endocarditis risk
- Functional baseline: Pre-stroke independence (modified Rankin Scale) affects treatment decisions and goals
- Living situation: Who can provide history? Who will assist with recovery?
Relevant Family History
| Family History Finding | Clinical Implication |
|---|---|
| Early stroke (before age 55) | Consider genetic or hypercoagulable causes; increased personal risk |
| Subarachnoid hemorrhage | First-degree relative with aneurysmal subarachnoid hemorrhage increases personal aneurysm risk; may warrant screening |
| Cardiomyopathy or sudden cardiac death | May suggest inherited cardiac disease predisposing to thromboembolism |
| Blood clotting disorders | Consider inherited thrombophilia (Factor V Leiden, prothrombin gene mutation) |
| Polycystic kidney disease | Associated with intracranial aneurysms |
4. Physical Examination
A systematic approach for sudden focal neurologic deficit
Dual Purpose of Examination: In acute stroke, the physical examination serves two purposes: (1) to localize the lesion within the nervous system and predict the affected vascular territory, and (2) to identify the underlying etiology (cardiac source, vascular disease, systemic illness). The examination must be rapid but thorough — every minute counts.
General Inspection
- Level of consciousness: Alert, drowsy, stuporous, comatose — decreasing consciousness suggests large hemispheric stroke, brainstem involvement, or elevated intracranial pressure
- Respiratory pattern: Cheyne-Stokes respiration (bilateral hemispheric or diencephalic), central neurogenic hyperventilation (midbrain), ataxic breathing (medulla)
- Posture: Spontaneous movement asymmetry, decorticate or decerebrate posturing (indicates severe dysfunction)
- Facial asymmetry: Central facial weakness (forehead spared) versus peripheral facial weakness (forehead involved — suggests Bell’s palsy, not stroke)
- Speech: Dysarthria (slurred speech with intact language) versus aphasia (language impairment); naming and repetition abnormalities
- Neglect: Patient ignoring one side of space; may not acknowledge affected limbs
Vital Signs
| Vital Sign | What to Look For | Clinical Significance |
|---|---|---|
| Blood Pressure | Severe hypertension (systolic greater than 220 or diastolic greater than 120); hypotension (systolic less than 90) | Severe hypertension suggests intracerebral hemorrhage or may require treatment before thrombolysis (goal less than 185/110). Hypotension is atypical for stroke — consider aortic dissection, sepsis, or cardiac cause |
| Heart Rate and Rhythm | Irregular rhythm; bradycardia; tachycardia | Irregular rhythm suggests atrial fibrillation (cardioembolic source). Bradycardia may indicate elevated intracranial pressure (Cushing reflex). Tachycardia may suggest sepsis, hyperthyroidism, or pain |
| Temperature | Fever (greater than 38°C) or hypothermia | Fever raises concern for infective endocarditis, meningitis, or aspiration pneumonia. Fever also worsens stroke outcomes |
| Respiratory Rate | Tachypnea, abnormal patterns | Tachypnea may indicate aspiration, pneumonia, or metabolic compensation. Irregular patterns suggest brainstem dysfunction |
| Oxygen Saturation | Hypoxemia (less than 94%) | May indicate aspiration, pulmonary embolism, or pneumonia. Hypoxemia worsens stroke outcomes — correct promptly |
| Fingerstick Glucose | Hypoglycemia (less than 60 mg/dL) or severe hyperglycemia (greater than 400 mg/dL) | Hypoglycemia can perfectly mimic stroke — must check in all patients. Hyperglycemia worsens stroke outcomes |
Neurological Examination: The NIH Stroke Scale
The National Institutes of Health Stroke Scale (NIHSS) is a standardized, validated tool for quantifying stroke severity. Scores range from 0 (no deficit) to 42 (maximum deficit). The NIHSS should be performed on all suspected stroke patients.
| NIHSS Component | What Is Tested | Scoring | Localizing Value |
|---|---|---|---|
| 1a. Level of Consciousness | Alertness | 0 = Alert; 1 = Drowsy; 2 = Stuporous; 3 = Coma | Large hemispheric stroke, brainstem, or elevated intracranial pressure |
| 1b. Level of Consciousness Questions | Month and age | 0 = Both correct; 1 = One correct; 2 = Neither correct | Dominant hemisphere involvement or global impairment |
| 1c. Level of Consciousness Commands | Open/close eyes, grip/release | 0 = Both correct; 1 = One correct; 2 = Neither correct | Tests comprehension and motor function |
| 2. Best Gaze | Horizontal eye movements | 0 = Normal; 1 = Partial gaze palsy; 2 = Forced deviation | Frontal eye field (gaze toward lesion) or brainstem (gaze away from lesion) |
| 3. Visual Fields | Visual field confrontation | 0 = Normal; 1 = Partial hemianopia; 2 = Complete hemianopia; 3 = Bilateral blindness | Optic radiation (parietal or temporal) or occipital cortex |
| 4. Facial Palsy | Facial symmetry, movement | 0 = Normal; 1 = Minor; 2 = Partial; 3 = Complete | Central (forehead spared) = hemispheric; Peripheral (forehead involved) = not stroke |
| 5. Motor Arm | Arm drift (tested separately for each arm) | 0 = No drift; 1 = Drift; 2 = Some effort against gravity; 3 = No effort against gravity; 4 = No movement | Motor cortex or corticospinal tract; arm more affected suggests middle cerebral artery territory |
| 6. Motor Leg | Leg drift (tested separately for each leg) | 0 = No drift; 1 = Drift; 2 = Some effort against gravity; 3 = No effort against gravity; 4 = No movement | Motor cortex or corticospinal tract; leg more affected suggests anterior cerebral artery territory |
| 7. Limb Ataxia | Finger-nose-finger, heel-shin | 0 = Absent; 1 = Present in one limb; 2 = Present in two limbs | Cerebellum or cerebellar connections |
| 8. Sensory | Pinprick sensation | 0 = Normal; 1 = Mild-moderate loss; 2 = Severe or total loss | Sensory cortex (parietal) or thalamus |
| 9. Best Language | Naming, reading, describing picture | 0 = Normal; 1 = Mild-moderate aphasia; 2 = Severe aphasia; 3 = Mute or global aphasia | Dominant hemisphere (usually left); Broca’s (frontal), Wernicke’s (temporal), or global |
| 10. Dysarthria | Speech clarity | 0 = Normal; 1 = Mild-moderate; 2 = Severe or unintelligible | Motor speech areas, brainstem, or cranial nerves |
| 11. Extinction and Inattention | Double simultaneous stimulation (visual and tactile) | 0 = Normal; 1 = One modality; 2 = Profound (both modalities) | Non-dominant hemisphere (usually right parietal) |
NIHSS Score Interpretation:
- 0: No stroke symptoms
- 1-4: Minor stroke
- 5-15: Moderate stroke
- 16-20: Moderate to severe stroke
- 21-42: Severe stroke
NIHSS greater than or equal to 6 with large vessel occlusion generally indicates thrombectomy candidacy. However, the NIHSS underestimates posterior circulation strokes, which may have devastating deficits with relatively low scores.
Additional Neurological Examination Elements
Pupillary Examination
Size: Anisocoria (unequal pupils) — dilated unreactive pupil suggests uncal herniation with third nerve compression
Reactivity: Bilateral fixed pupils suggests severe brainstem dysfunction
Horner syndrome: Miosis, ptosis, anhidrosis — suggests carotid dissection or lateral medullary stroke
Cerebellar Examination
Finger-nose-finger: Intention tremor, past-pointing
Heel-shin: Dysmetria on sliding heel down shin
Gait: Wide-based, ataxic (if patient can walk safely)
Key point: Cerebellar stroke can deteriorate rapidly due to posterior fossa swelling — monitor closely
Brainstem Signs
| Finding | Localization | Associated Syndrome |
|---|---|---|
| Crossed deficits (ipsilateral face, contralateral body) | Brainstem | Multiple brainstem syndromes |
| Ipsilateral Horner syndrome + contralateral pain/temperature loss | Lateral medulla | Wallenberg syndrome (lateral medullary syndrome) |
| Quadriplegia with preserved consciousness and vertical eye movement | Ventral pons | Locked-in syndrome |
| Internuclear ophthalmoplegia | Medial longitudinal fasciculus | Brainstem stroke or multiple sclerosis |
| Nystagmus + vertigo + ataxia without hearing loss | Cerebellum or brainstem vestibular nuclei | Posterior circulation stroke (distinguish from peripheral vertigo) |
Cardiovascular Examination
Cardiac Auscultation
- Irregular rhythm: Atrial fibrillation — most common cardiac embolic source
- Murmurs: New murmur raises concern for endocarditis (especially with fever) or valvular disease
- Third heart sound (S3): May indicate cardiomyopathy with risk of left ventricular thrombus
Vascular Examination
- Carotid bruits: May indicate carotid stenosis (though absence does not exclude it)
- Blood pressure in both arms: Greater than 20 mmHg difference suggests subclavian stenosis or aortic dissection
- Peripheral pulses: Asymmetric or absent pulses raise concern for systemic atherosclerosis or aortic dissection
Examination Clues to Stroke Etiology
| Physical Finding | Suggested Etiology | Next Step |
|---|---|---|
| Irregularly irregular pulse | Atrial fibrillation (cardioembolism) | ECG, echocardiography, long-term cardiac monitoring |
| Carotid bruit | Carotid stenosis (large vessel atherosclerosis) | Carotid ultrasound or CT angiography |
| Horner syndrome + neck pain | Carotid dissection | CT angiography or MR angiography of neck |
| Fever + new murmur + splinter hemorrhages | Infective endocarditis with septic embolism | Blood cultures, echocardiography (transesophageal preferred) |
| Livedo reticularis + renal dysfunction | Cholesterol embolism syndrome | Consider recent vascular procedure; may see eosinophilia |
| Track marks (intravenous drug use) | Endocarditis (right-sided initially, but can embolize paradoxically) | Blood cultures, echocardiography, consider paradoxical embolism |
| Xanthomas, arcus corneae | Hyperlipidemia with accelerated atherosclerosis | Lipid panel, vascular imaging |
| Marfanoid habitus | Connective tissue disorder predisposing to dissection | Vascular imaging, genetics consultation |
Expected Findings by Vascular Territory
| Vascular Territory | Motor Findings | Sensory Findings | Other Key Findings |
|---|---|---|---|
| Middle Cerebral Artery (MCA) | Face and arm weakness greater than leg (contralateral) | Face and arm sensory loss greater than leg | Aphasia (dominant), neglect (non-dominant), gaze deviation toward lesion, homonymous hemianopia |
| Anterior Cerebral Artery (ACA) | Leg weakness greater than arm (contralateral) | Leg sensory loss greater than arm | Abulia, urinary incontinence, alien hand syndrome, grasp reflex |
| Posterior Cerebral Artery (PCA) | Usually minimal motor deficit | Contralateral hemisensory loss (thalamic involvement) | Homonymous hemianopia with macular sparing, visual agnosia, alexia without agraphia (dominant) |
| Basilar Artery | Quadriparesis (ventral pons) or variable | Variable bilateral sensory involvement | Cranial nerve palsies, coma, locked-in syndrome, “top of the basilar” syndrome with somnolence and visual deficits |
| Lateral Medullary (Wallenberg) | Ipsilateral ataxia; no limb weakness | Ipsilateral face + contralateral body pain/temperature loss | Ipsilateral Horner syndrome, dysphagia, dysarthria, vertigo, nystagmus |
| Lacunar (Small Vessel) | Pure motor hemiparesis (internal capsule) or ataxic hemiparesis | Pure sensory stroke (thalamus) or sensorimotor stroke | No cortical signs (no aphasia, no neglect, no visual field cut, no altered consciousness) |
Important Teaching Point
Posterior circulation strokes are frequently missed. The “5 D’s” of vertebrobasilar stroke — Dizziness, Diplopia, Dysarthria, Dysphagia, and Dystaxia (ataxia) — may be subtle and overlooked, especially when presenting as isolated vertigo. Key distinguishing features of central (stroke) versus peripheral (benign) vertigo include: direction-changing nystagmus, inability to walk, negative head impulse test, vertical or torsional nystagmus, and new neurological signs. When in doubt, imaging is essential.
5. Differential Diagnosis
Systematic approach organized by probability and clinical features
The differential diagnosis of sudden focal neurologic deficit extends beyond stroke to include numerous “stroke mimics” that account for 20-30% of acute stroke alerts. Accurate differentiation is critical because thrombolytic therapy carries bleeding risk and should not be administered for non-ischemic conditions. However, the time-sensitive nature of true stroke means that diagnostic uncertainty should not delay treatment when clinical suspicion is high and imaging supports the diagnosis.
True Stroke versus Stroke Mimics
| Category | Condition | Approximate Frequency | Key Distinguishing Features |
|---|---|---|---|
| TRUE STROKE (70-80% of stroke alerts) | Ischemic stroke | 60-65% | Sudden onset, deficit corresponds to vascular territory, CT shows early ischemic changes or is normal, MRI shows restricted diffusion |
| Intracerebral hemorrhage | 10-12% | Often more headache and vomiting, progressive deterioration, CT shows hyperdense blood | |
| Subarachnoid hemorrhage | 2-3% | Thunderclap headache predominates, neck stiffness, CT shows subarachnoid blood | |
| STROKE MIMICS (20-30% of stroke alerts) | Seizure with postictal (Todd’s) paralysis | 5-8% | Witnessed seizure activity, symptoms improving, history of epilepsy, tongue bite, incontinence |
| Migraine with aura (complex or hemiplegic) | 3-5% | Gradual march of symptoms over 20-60 minutes, history of similar events, subsequent headache, younger patient | |
| Hypoglycemia | 2-4% | Diabetic patient, low fingerstick glucose, rapid resolution with glucose administration | |
| Functional (psychogenic) neurological disorder | 2-4% | Inconsistent examination, give-way weakness, positive Hoover sign, symptoms not conforming to neuroanatomy | |
| Toxic-metabolic encephalopathy | 2-3% | Confusion predominates, often bilateral findings, abnormal metabolic panel (hyponatremia, uremia, hepatic encephalopathy) | |
| Brain tumor (new presentation or with seizure) | 1-2% | May have subacute symptoms preceding acute event, mass effect on imaging |
Ischemic Stroke: Differential by Mechanism (TOAST Classification)
Step-by-Step Approach to Ischemic Stroke Etiology:
- Step 1: Confirm ischemic stroke — exclude hemorrhage with CT, confirm infarct with MRI diffusion-weighted imaging
- Step 2: Assess stroke pattern — single territory (embolic or local thrombosis) versus watershed (hypoperfusion) versus multiple territories (proximal embolic source)
- Step 3: Evaluate large vessels — carotid and intracranial arterial imaging
- Step 4: Evaluate cardiac sources — ECG, echocardiography, prolonged cardiac monitoring
- Step 5: Consider less common causes — especially in young patients or those without traditional risk factors
| Mechanism | Approximate Frequency | Key Features | Diagnostic Criteria |
|---|---|---|---|
| Large Artery Atherosclerosis | 15-20% | Preceding transient ischemic attacks (often stereotyped), cortical or large subcortical infarct, vascular risk factors | Greater than 50% stenosis of relevant extracranial or intracranial artery; or less than 50% with ulcerated plaque |
| Cardioembolism | 20-30% | Sudden maximal onset, cortical infarct, multiple vascular territories, known cardiac source | High-risk cardiac source identified (atrial fibrillation, mechanical valve, recent myocardial infarction with thrombus, infective endocarditis) |
| Small Vessel Occlusion (Lacunar) | 20-25% | Classic lacunar syndrome, small deep infarct (less than 1.5 cm), no cortical signs, hypertension and diabetes | One of classic lacunar syndromes, small subcortical infarct on imaging, no cardiac source or large vessel disease |
| Other Determined Cause | 5% | Younger patient, no traditional risk factors, specific clinical features | Identified cause: dissection, vasculitis, hypercoagulable state, moyamoya, and others |
| Cryptogenic (Undetermined) | 25-30% | Complete workup negative, or multiple competing causes, or incomplete evaluation | No identified etiology despite standard workup; consider extended cardiac monitoring and patent foramen ovale evaluation |
Hemorrhagic Stroke: Differential by Cause
| Probability | Condition | Typical Patient and Location | Key Features |
|---|---|---|---|
| COMMON | Hypertensive intracerebral hemorrhage | Older patient with chronic hypertension; deep locations (putamen, thalamus, pons, cerebellum) | Severely elevated blood pressure, gradual progression over minutes to hours, deep location on CT |
| COMMON | Cerebral amyloid angiopathy | Elderly patient (usually greater than 65 years); lobar (cortical-subcortical) location | Recurrent lobar hemorrhages, associated dementia, microbleeds on MRI gradient echo |
| LESS COMMON | Anticoagulation-related hemorrhage | Any patient on anticoagulation; any location | On warfarin with elevated INR, or on direct oral anticoagulant; may expand rapidly; requires reversal |
| LESS COMMON | Aneurysmal subarachnoid hemorrhage | Often younger (40-60 years); subarachnoid space, often with intraventricular extension | Thunderclap headache, meningismus, CT shows subarachnoid blood, angiography confirms aneurysm |
| UNCOMMON | Arteriovenous malformation rupture | Younger patient (20-40 years); lobar or deep location | May have prior seizures or headaches; angiography shows nidus and feeding vessels |
| UNCOMMON | Hemorrhagic transformation of ischemic stroke | Within territory of prior ischemic infarct | Recent ischemic stroke (especially cardioembolic), post-thrombolysis, or spontaneous reperfusion |
| UNCOMMON | Cerebral venous thrombosis with hemorrhagic infarct | Young woman, peripartum, hypercoagulable state; does not conform to arterial territory | Headache predominates, may have seizures, hemorrhage crosses arterial boundaries, “cord sign” on CT |
| UNCOMMON | Hemorrhage into brain tumor | History of cancer (especially melanoma, renal cell, choriocarcinoma, lung, thyroid) | Surrounding edema disproportionate to hemorrhage size, irregular margins, multiple lesions |
Anatomical Approach to Sudden Focal Deficit
Anterior Circulation — Cortical
Middle cerebral artery stroke (most common)
Anterior cerebral artery stroke
Carotid dissection with embolism
Cerebral venous thrombosis
Cortical vein thrombosis
Lobar hemorrhage (amyloid angiopathy)
Anterior Circulation — Subcortical
Lacunar infarcts (internal capsule, corona radiata)
Hypertensive hemorrhage (putamen, caudate)
Thalamic infarct or hemorrhage
Lenticulostriate artery occlusion
Deep middle cerebral artery territory stroke
Posterior Circulation — Brainstem
Basilar artery occlusion
Lateral medullary (Wallenberg) syndrome
Medial medullary syndrome
Pontine stroke (lacunar or large vessel)
Midbrain stroke
Vertebral artery dissection
Posterior Circulation — Cerebellar and Occipital
Posterior cerebral artery stroke
Cerebellar infarct (posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery)
Cerebellar hemorrhage
Top of the basilar syndrome
Posterior reversible encephalopathy syndrome
Stroke Mimics: Detailed Differential
| Condition | Mechanism | Key Distinguishing Features | Diagnostic Approach |
|---|---|---|---|
| Seizure with postictal (Todd’s) paralysis | Cortical exhaustion and transient inhibition following ictal activity | Witnessed convulsive activity, tongue bite, incontinence, gradual improvement over minutes to hours, history of epilepsy | Observe for improvement; EEG if unclear; MRI may show no acute changes or periictal changes |
| Migraine with aura (hemiplegic migraine) | Cortical spreading depression causing transient neuronal dysfunction | Gradual “march” of symptoms over 20-60 minutes (visual → sensory → motor), history of similar events, subsequent headache, younger patient | Clinical diagnosis based on history; MRI negative for infarct; may show perfusion changes during aura |
| Hypoglycemia | Insufficient glucose for neuronal metabolism; focal deficits may occur with blood glucose less than 50 mg/dL | Diabetic on insulin or sulfonylureas, altered consciousness, diaphoresis, rapid resolution with glucose | Fingerstick glucose (must check in ALL stroke alerts); response to glucose administration |
| Functional (psychogenic) neurological disorder | Functional disruption of neural networks without structural damage | Positive signs: Hoover sign, give-way weakness, inconsistent examination, symptoms not conforming to neuroanatomy, distractibility | Positive functional signs on examination; normal imaging; diagnosis of inclusion, not exclusion |
| Toxic-metabolic encephalopathy | Global brain dysfunction from metabolic derangement | Confusion and altered consciousness predominate; often bilateral or fluctuating signs; identifiable metabolic cause | Comprehensive metabolic panel, ammonia, drug screen; treat underlying cause |
| Brain tumor | Mass effect, edema, seizure, or hemorrhage into tumor | May have subacute prodrome (headaches, cognitive change); seizure at presentation; mass with edema on imaging | CT shows mass with edema; MRI for characterization; biopsy for diagnosis |
| Subdural hematoma | Mass effect from extra-axial blood collection | History of trauma (may be minor in elderly on anticoagulation); fluctuating symptoms; crescent-shaped collection on CT | CT shows extra-axial collection; may require surgical evacuation |
| Multiple sclerosis (acute relapse) | Inflammatory demyelination of central nervous system | Younger patient, symptoms evolving over hours to days (not seconds), prior episodes, MRI shows white matter lesions | MRI with contrast shows enhancing lesions; lumbar puncture shows oligoclonal bands |
| Peripheral vestibular disorder (presenting as “posterior circulation stroke”) | Inner ear or vestibular nerve dysfunction | Isolated vertigo, positive head impulse test, unidirectional nystagmus suppressed by fixation, no other neurological signs | HINTS examination (Head Impulse, Nystagmus, Test of Skew); MRI if any central features |
| Wernicke encephalopathy | Thiamine deficiency affecting mammillary bodies, thalami, periaqueductal gray | Triad of confusion, ataxia, ophthalmoplegia; history of alcohol use disorder or malnutrition | Clinical diagnosis; treat empirically with thiamine; MRI may show characteristic changes |
Drug-Induced and Iatrogenic Causes of Sudden Focal Deficit
| Drug or Situation | Mechanism | Characteristics | Management |
|---|---|---|---|
| Cocaine | Vasoconstriction, vasospasm, accelerated atherosclerosis, cardioembolism (cocaine-induced cardiomyopathy) | Both ischemic and hemorrhagic stroke; often in young patients; may have chest pain | Avoid beta-blockers (unopposed alpha); treat hypertension with benzodiazepines, calcium channel blockers |
| Amphetamines and methamphetamine | Hypertensive crisis, vasculitis, cardiomyopathy | Intracerebral hemorrhage more common; may occur during or shortly after use | Blood pressure control; supportive care; evaluate for underlying vascular abnormality |
| Oral contraceptives and hormone replacement | Hypercoagulable state; increased risk of cerebral venous thrombosis and arterial ischemic stroke | Young women; risk increased with smoking, migraine with aura, or underlying thrombophilia | Discontinue; anticoagulation if venous thrombosis; consider thrombophilia workup |
| Anticoagulants (warfarin, direct oral anticoagulants) | Bleeding diathesis leading to intracerebral hemorrhage | Hemorrhagic stroke; may expand rapidly; warfarin: elevated INR; direct oral anticoagulants: recent dose | Reversal agents: vitamin K and prothrombin complex concentrate for warfarin; idarucizumab for dabigatran; andexanet alfa for factor Xa inhibitors |
| Thrombolytic therapy (tissue plasminogen activator) | Hemorrhagic transformation of ischemic infarct or systemic bleeding | Symptomatic intracerebral hemorrhage in 2-7% of treated patients; neurological deterioration during or after infusion | Stop infusion immediately; emergent CT; cryoprecipitate and tranexamic acid; blood pressure control |
| Post-procedural (cardiac catheterization, carotid stenting) | Embolism of air, thrombus, or plaque debris; dissection; hypotension | Onset during or shortly after procedure; distribution depends on embolic source | Immediate vascular imaging; thrombectomy if large vessel occlusion; supportive care |
| Chemotherapy agents (L-asparaginase, bevacizumab) | Hypercoagulable state (L-asparaginase); hemorrhage or posterior reversible encephalopathy syndrome (bevacizumab) | Cancer patients on active therapy; may have atypical presentations | Hold offending agent; standard stroke management; oncology consultation |
Quick Reference: “If You See This, Think This”
| Clinical Clue | Think This First | Next Step |
|---|---|---|
| Thunderclap headache with focal deficit | Subarachnoid hemorrhage | Emergent non-contrast CT head; if negative, lumbar puncture |
| Neck pain preceding or with focal deficit in young patient | Cervical artery dissection | CT angiography or MR angiography of head and neck |
| Irregular pulse with sudden maximal deficit | Cardioembolic stroke from atrial fibrillation | ECG, echocardiography, anticoagulation for secondary prevention |
| Crossed deficits (ipsilateral face, contralateral body) | Brainstem stroke | MRI with diffusion-weighted imaging (CT often misses brainstem strokes) |
| Vertigo, ataxia, dysarthria, and diplopia | Posterior circulation stroke | MRI; do not dismiss as “peripheral vertigo” without thorough evaluation |
| Witnessed seizure followed by weakness | Postictal (Todd’s) paralysis | Observe for improvement; EEG; MRI to rule out underlying lesion |
| Diabetic patient with focal deficit and altered consciousness | Hypoglycemia | Immediate fingerstick glucose; treat if low |
| Gradual march of symptoms over 20-60 minutes with subsequent headache | Migraine with aura (hemiplegic migraine) | History of similar events; MRI to exclude stroke if first episode |
| Young woman with headache, papilledema, and seizures | Cerebral venous thrombosis | CT venography or MR venography |
| Fever, new murmur, and multifocal deficits | Infective endocarditis with septic emboli | Blood cultures, transesophageal echocardiography |
| Cocaine use with severe headache and focal deficit | Cocaine-induced hemorrhagic or ischemic stroke | CT head (often hemorrhagic); avoid beta-blockers |
| Give-way weakness, Hoover sign positive, inconsistent examination | Functional neurological disorder | Document positive functional signs; MRI to exclude structural cause; neurology and psychiatry consultation |
6. Diagnostic Investigations
A stepwise, time-sensitive approach guided by clinical suspicion
Key Principle: In acute stroke, investigations must be performed rapidly without delaying treatment. The only test required before thrombolysis is non-contrast CT head (to exclude hemorrhage). Fingerstick glucose should be checked, but a full metabolic panel should not delay treatment. Other investigations can proceed in parallel or after acute treatment.
Emergent Investigations (Required Before Thrombolysis)
| Investigation | Purpose | What to Look For | Critical Points |
|---|---|---|---|
| Non-contrast CT head | Exclude intracranial hemorrhage; identify early ischemic changes | Hyperdense blood (hemorrhage); hypodense changes, loss of gray-white differentiation, sulcal effacement (early ischemia); hyperdense vessel sign (thrombus) | MUST be obtained before thrombolysis. May be normal in early ischemic stroke. Door-to-CT time goal: less than 25 minutes |
| Fingerstick glucose | Exclude hypoglycemia (stroke mimic) | Hypoglycemia (less than 60 mg/dL) can mimic stroke and must be corrected | Required before thrombolysis. Hyperglycemia (greater than 180 mg/dL) worsens outcomes and should be treated |
| ECG | Identify atrial fibrillation; detect concurrent myocardial infarction | Atrial fibrillation (cardioembolic source); ST changes (concurrent acute coronary syndrome or demand ischemia) | Should not delay thrombolysis, but obtain as soon as practical |
Do NOT Delay Thrombolysis For:
- Complete blood count results (unless clinical suspicion of thrombocytopenia or bleeding disorder)
- Coagulation studies (unless patient is on anticoagulation)
- Comprehensive metabolic panel
- Chest radiograph
- Lumbar puncture (unless subarachnoid hemorrhage suspected with negative CT)
These tests should be sent but results awaited only if there is specific clinical concern.
Advanced Imaging for Treatment Decisions
| Investigation | Purpose | Key Findings | When to Order |
|---|---|---|---|
| CT angiography (CTA) of head and neck | Identify large vessel occlusion for thrombectomy; detect cervical artery dissection or stenosis | Intracranial large vessel occlusion (internal carotid artery terminus, M1, M2 middle cerebral artery, basilar artery); carotid or vertebral stenosis or dissection | All patients being considered for thrombectomy; ideally performed with initial non-contrast CT |
| CT perfusion (CTP) | Identify salvageable penumbra versus irreversible core; guide thrombectomy in extended time window | Core (severely reduced cerebral blood flow and cerebral blood volume); Penumbra (reduced blood flow but preserved blood volume); Mismatch ratio guides treatment | Patients presenting 6-24 hours from last known well; wake-up stroke with unknown onset time |
| MRI with diffusion-weighted imaging (DWI) | Confirm acute ischemic stroke; detect strokes missed on CT (especially brainstem, small cortical) | Restricted diffusion (bright on DWI, dark on ADC) confirms acute infarct within minutes of onset | Diagnostic uncertainty; suspected posterior circulation stroke; CT-negative but high clinical suspicion |
| MR angiography (MRA) | Non-invasive vascular imaging; alternative to CTA | Similar to CTA for detecting stenosis, occlusion, dissection | Renal insufficiency (avoid contrast); allergy to iodinated contrast; outpatient evaluation |
Laboratory Investigations
Baseline Laboratory Panel for All Stroke Patients
| Test | Purpose | Key Abnormalities | Clinical Implications |
|---|---|---|---|
| Complete blood count | Detect anemia, thrombocytopenia, polycythemia, leukocytosis | Platelets less than 100,000: relative contraindication to thrombolysis; Elevated white blood cell count: infection | Polycythemia and thrombocytosis increase stroke risk; anemia may worsen outcomes |
| Basic metabolic panel | Detect electrolyte abnormalities, renal function, glucose | Hyponatremia: may cause altered mental status; Hyperglycemia: worsens outcomes; Renal insufficiency: affects contrast use | Correct severe abnormalities; adjust contrast dosing for renal function |
| Coagulation studies (PT/INR, aPTT) | Assess anticoagulation status | INR greater than 1.7: contraindication to thrombolysis (relative); Elevated aPTT: may indicate heparin effect or coagulopathy | Required if patient on warfarin or heparin; direct oral anticoagulant levels if available |
| Troponin | Detect concurrent myocardial infarction or demand ischemia | Elevated troponin common in stroke (cardiac source or demand ischemia) | May indicate cardiac source of embolism; guides cardiac workup and monitoring |
| Lipid panel (fasting) | Assess cardiovascular risk; guide secondary prevention | Elevated LDL-cholesterol; low HDL-cholesterol | High-intensity statin therapy indicated for most ischemic stroke patients |
| Hemoglobin A1c | Assess glycemic control; screen for diabetes | HbA1c greater than or equal to 6.5% indicates diabetes; 5.7-6.4% indicates prediabetes | Diabetes is major modifiable risk factor; optimize glycemic control for secondary prevention |
Targeted Investigations by Suspected Etiology
If Suspecting Cardioembolic Stroke
First-Line Tests
- 12-lead ECG: Atrial fibrillation present in approximately 25% of cardioembolic strokes
- Transthoracic echocardiography: Left atrial enlargement, valvular abnormalities, wall motion abnormalities, left ventricular thrombus
- Telemetry monitoring: At least 24 hours; detects paroxysmal atrial fibrillation in additional 5-10%
Second-Line Tests
- Transesophageal echocardiography: Superior for left atrial appendage thrombus, patent foramen ovale, atrial septal aneurysm, aortic arch atheroma
- Extended cardiac monitoring (14-30 days): Implantable loop recorder detects atrial fibrillation in additional 10-20% of cryptogenic strokes
- Bubble study: Detects right-to-left shunt (patent foramen ovale)
If Suspecting Large Vessel Atherosclerosis
First-Line Tests
- CTA head and neck: Gold standard for detecting stenosis, occlusion, plaque morphology
- Carotid ultrasound: Non-invasive assessment of extracranial carotid stenosis; operator-dependent
Second-Line Tests
- MRA head and neck: Alternative to CTA; may overestimate stenosis
- Transcranial Doppler: Intracranial stenosis, microembolic signals, vasospasm monitoring
- Digital subtraction angiography: Gold standard but invasive; reserved for intervention planning or diagnostic uncertainty
If Suspecting Cervical Artery Dissection
Imaging of Choice
- CTA head and neck: Detects intimal flap, luminal stenosis, intramural hematoma, pseudoaneurysm
- MRA with fat-suppressed T1 sequences: Excellent for detecting intramural hematoma (crescent sign)
Additional Considerations
- Conventional angiography: Rarely needed; consider if diagnosis uncertain
- Consider connective tissue disorder workup if spontaneous dissection in young patient (Ehlers-Danlos syndrome, Marfan syndrome)
If Suspecting Subarachnoid Hemorrhage
First-Line Tests
- Non-contrast CT head: Sensitivity greater than 98% within 6 hours; decreases over time
- CTA head: Identifies aneurysm in majority of cases; can be done immediately after non-contrast CT
Second-Line Tests
- Lumbar puncture: If CT negative but clinical suspicion high; look for xanthochromia (yellowish discoloration from bilirubin), elevated red blood cell count that does not clear
- Digital subtraction angiography: Gold standard for aneurysm detection if CTA negative; may need to repeat if initial study negative
If Suspecting Cerebral Venous Thrombosis
Imaging
- CT venography: Filling defect in venous sinuses; “empty delta sign” in superior sagittal sinus
- MR venography: Absence of flow signal in affected sinus; preferred for follow-up
Additional Workup
- Thrombophilia panel: Factor V Leiden, prothrombin gene mutation, protein C, protein S, antithrombin, antiphospholipid antibodies (test after acute phase)
- Consider underlying cause: Pregnancy, oral contraceptives, dehydration, infection (mastoiditis, meningitis), malignancy
Extended Workup for Young Patients (Under Age 50) or Cryptogenic Stroke
Consider Additional Testing
- Hypercoagulable panel: Factor V Leiden, prothrombin G20210A mutation, protein C, protein S, antithrombin III, antiphospholipid antibodies (lupus anticoagulant, anticardiolipin, anti-beta-2 glycoprotein) — test at least 2-4 weeks after acute event and off anticoagulation for most accurate results
- Transesophageal echocardiography with bubble study: Patent foramen ovale with atrial septal aneurysm; aortic arch atheroma
- Extended cardiac monitoring: Implantable loop recorder for up to 3 years to detect paroxysmal atrial fibrillation
- Inflammatory markers: ESR, CRP, ANA — if suspecting vasculitis
- Vasculitis workup: ANCA, complement levels, infectious serologies (HIV, syphilis, hepatitis), cerebrospinal fluid analysis if primary central nervous system vasculitis suspected
- Genetic testing: CADASIL (NOTCH3 mutation) if multiple strokes with white matter disease and family history; Fabry disease (alpha-galactosidase A deficiency) if appropriate clinical features
- Toxicology screen: Cocaine, amphetamines — can cause both ischemic and hemorrhagic stroke
Investigations for Intracerebral Hemorrhage
| Investigation | Purpose | When to Order |
|---|---|---|
| Non-contrast CT head | Confirm hemorrhage location, size, presence of intraventricular extension, mass effect, hydrocephalus | All patients — this is the primary diagnostic test |
| CTA head (spot sign protocol) | Identify contrast extravasation (“spot sign”) predicting hematoma expansion; detect underlying vascular malformation | All patients with intracerebral hemorrhage; especially if young or atypical location |
| Coagulation studies (PT/INR, aPTT) | Identify coagulopathy requiring reversal | All patients — especially if on anticoagulation |
| Drug screen | Identify cocaine or amphetamine-related hemorrhage | Young patients; patients without hypertension; clinical suspicion of drug use |
| MRI with gradient echo or susceptibility-weighted imaging | Detect microbleeds suggesting cerebral amyloid angiopathy or hypertensive microangiopathy; identify underlying tumor | After acute phase stabilization; especially if lobar hemorrhage or recurrent hemorrhage |
| Digital subtraction angiography | Detect aneurysm, arteriovenous malformation, dural fistula not seen on CTA | Young patient with lobar hemorrhage; atypical location; negative CTA with high suspicion |
7. Pattern Recognition and Clinical Decision-Making
Practical algorithms and decision pathways for acute stroke management
Clinical decision-making in acute stroke is uniquely time-sensitive. The phrase “time is brain” reflects the narrow therapeutic windows for reperfusion therapy. This section provides practical algorithms to guide rapid assessment, treatment eligibility determination, and appropriate triage.
Step 1: Is This an Emergency?
| Clinical Scenario | Urgency Level | Immediate Action |
|---|---|---|
| Acute focal deficit within 4.5 hours of last known well | EMERGENT — Minutes matter | Activate stroke code; CT immediately; evaluate for intravenous thrombolysis; notify interventional team |
| Acute focal deficit 4.5-24 hours or wake-up stroke | EMERGENT | CT and CTA immediately; CT perfusion for extended window thrombectomy eligibility; may still qualify for intervention |
| Thunderclap headache with or without focal deficit | EMERGENT | Assume subarachnoid hemorrhage until proven otherwise; emergent CT; if negative, lumbar puncture |
| Rapidly deteriorating level of consciousness | EMERGENT | Airway protection; emergent CT; consider large hemorrhage, basilar occlusion, or herniation; neurosurgery consultation |
| Cerebellar stroke with deterioration | EMERGENT | Risk of rapid herniation; immediate neurosurgery consultation; may need emergent decompression |
| Transient symptoms fully resolved, within 24-48 hours | URGENT | Admit for expedited workup; high short-term stroke risk (ABCD2 score); initiate secondary prevention |
| Transient symptoms resolved more than 48 hours ago | URGENT OUTPATIENT | Expedited outpatient workup within 24-72 hours; start antiplatelet therapy; risk factor modification |
Step 2: Determine Treatment Eligibility by Time Window
0-4.5 Hours
Intravenous thrombolysis window
Alteplase or tenecteplase eligible if no contraindications
Door-to-needle goal: less than 60 minutes
0-24 Hours
Mechanical thrombectomy window
For large vessel occlusion with favorable imaging
CT perfusion guides selection in extended window
Beyond 24 Hours
Secondary prevention focus
Complete etiological workup
Initiate appropriate antithrombotic and risk factor management
Step 3: Intravenous Thrombolysis Decision Algorithm
Key Inclusion Criteria for Intravenous Alteplase/Tenecteplase:
- Clinical diagnosis of ischemic stroke causing measurable neurological deficit
- Symptom onset (or last known well) within 4.5 hours
- Age 18 years or older
- CT excludes intracranial hemorrhage
| Contraindication Category | Absolute Contraindications | Relative Contraindications (Weigh Risk-Benefit) |
|---|---|---|
| Hemorrhage Risk | Intracranial hemorrhage on CT; known intracranial neoplasm, aneurysm, or arteriovenous malformation; recent intracranial or spinal surgery | Recent major surgery (14 days); recent gastrointestinal or genitourinary hemorrhage (21 days); recent arterial puncture at non-compressible site (7 days) |
| Coagulation | Current anticoagulation with INR greater than 1.7; heparin within 48 hours with elevated aPTT; direct oral anticoagulant within 48 hours (unless specific assays negative); platelets less than 100,000 | INR 1.5-1.7 (may consider with careful risk-benefit); unknown coagulation status in patient not on anticoagulation (do not delay) |
| Blood Pressure | Blood pressure greater than 185/110 mmHg despite treatment | Blood pressure initially elevated but controlled with treatment to less than 185/110 |
| Blood Glucose | Blood glucose less than 50 mg/dL (treat hypoglycemia first; symptoms may resolve) | Severe hyperglycemia (greater than 400 mg/dL) — associated with worse outcomes but not absolute contraindication |
| Stroke Severity | None absolute | Minor or rapidly improving symptoms (but do not withhold if deficits persist and are disabling); severe stroke with NIHSS greater than 25 (higher hemorrhage risk but still may benefit) |
| Recent Stroke | Ischemic stroke within past 3 months (0-3 hour window); any stroke within 3 months for 3-4.5 hour window | Prior stroke with residual deficit — consider current deficit severity and disability |
| 3-4.5 Hour Window Additional | Age greater than 80 years combined with prior stroke and diabetes; oral anticoagulant use regardless of INR (per original trials, though often treated in practice) | Age greater than 80 alone is not a contraindication; severe stroke (NIHSS greater than 25) |
Step 4: Mechanical Thrombectomy Decision Algorithm
| Time Window | Eligibility Criteria | Key Imaging Requirements |
|---|---|---|
| 0-6 hours from last known well | Large vessel occlusion (internal carotid artery, M1 middle cerebral artery, proximal M2); NIHSS generally 6 or greater; pre-stroke modified Rankin Scale 0-1 | CTA confirms large vessel occlusion; CT shows no large established infarct (ASPECTS 6 or greater) |
| 6-24 hours from last known well (DAWN/DEFUSE 3 criteria) | Large vessel occlusion; clinical-core mismatch (significant deficit with small infarct core); pre-stroke modified Rankin Scale 0-1 | CT perfusion or MRI perfusion required; infarct core less than 70 mL (DAWN) or less than 70 mL with mismatch ratio greater than 1.8 (DEFUSE 3) |
| Basilar artery occlusion (ATTENTION/BAOCHE trials) | Basilar artery occlusion confirmed on CTA; within 24 hours; NIHSS 10 or greater | CTA confirms basilar occlusion; consider posterior circulation ASPECTS (pc-ASPECTS) |
Thrombectomy Does NOT Replace Thrombolysis
Patients eligible for both intravenous thrombolysis and mechanical thrombectomy should receive both. Thrombolysis should be given as soon as possible and should not be delayed for transfer or thrombectomy preparation. “Drip and ship” protocols allow thrombolysis at non-thrombectomy centers before transfer. Recent trials suggest tenecteplase may be superior to alteplase before thrombectomy.
Step 5: Intracerebral Hemorrhage Management Decisions
| Decision Point | Criteria | Action |
|---|---|---|
| Blood pressure management | Systolic blood pressure greater than 150 mmHg; presenting within 6 hours | Target systolic blood pressure 130-140 mmHg (avoid below 130); use intravenous labetalol or nicardipine; maintain adequate cerebral perfusion |
| Anticoagulation reversal | On warfarin with elevated INR; on direct oral anticoagulant; on heparin | Warfarin: 4-factor prothrombin complex concentrate plus vitamin K; Dabigatran: idarucizumab; Factor Xa inhibitors: andexanet alfa or 4-factor prothrombin complex concentrate; Heparin: protamine |
| Surgical evacuation consideration | Cerebellar hemorrhage greater than 3 cm or with brainstem compression or hydrocephalus; lobar hemorrhage greater than 30 mL within 1 cm of surface in deteriorating patient | Emergent neurosurgery consultation; cerebellar hemorrhage with deterioration is surgical emergency |
| External ventricular drain | Hydrocephalus with intraventricular hemorrhage and declining level of consciousness | Neurosurgery consultation for external ventricular drain placement |
| Goals of care discussion | Large hemorrhage with poor prognosis; patient’s prior wishes unknown | Early palliative care involvement; avoid premature withdrawal of care — prognosis difficult to determine in first 24-48 hours |
“What Do I Do If…” Decision Reference
| Clinical Situation | Immediate Action | Next Step |
|---|---|---|
| Patient arrives at 3 hours, blood pressure 200/115 | Treat blood pressure to less than 185/110 before thrombolysis (labetalol or nicardipine) | If controlled within 15-20 minutes, proceed with thrombolysis; if refractory, thrombolysis contraindicated but consider thrombectomy |
| Patient on warfarin with INR 1.5 | INR less than 1.7 is generally acceptable for thrombolysis | Proceed with thrombolysis if otherwise eligible; have reversal agents available |
| Patient on apixaban, last dose 10 hours ago | Direct oral anticoagulant within 48 hours is relative contraindication; check anti-Xa level if available rapidly | If anti-Xa level less than 30 ng/mL, may consider thrombolysis; if unavailable or elevated, proceed directly to thrombectomy if large vessel occlusion; otherwise, supportive care |
| Symptoms rapidly improving during evaluation | Document serial NIHSS; assess if residual deficit is disabling | If deficit is disabling (cannot use hand, cannot walk), treat; if truly minor and non-disabling, may observe but ensure complete workup |
| Wake-up stroke with unknown time of onset | Obtain CT and CTA immediately; add CT perfusion for extended window evaluation | If favorable perfusion mismatch (small core, large penumbra), thrombectomy eligible up to 24 hours; consider thrombolysis if MRI shows DWI-FLAIR mismatch |
| Large vessel occlusion but outside thrombolysis window | Proceed directly to thrombectomy evaluation; obtain CT perfusion | Thrombectomy alone (without thrombolysis) if favorable imaging within 24-hour window |
| Neurological deterioration after thrombolysis | Stop infusion immediately; emergent CT to evaluate for hemorrhage | If hemorrhage: cryoprecipitate, tranexamic acid, blood pressure control, neurosurgery consultation; if no hemorrhage: consider reocclusion, edema, or other cause |
| Suspected posterior circulation stroke with vertigo | Do not dismiss as peripheral vertigo without thorough evaluation | HINTS examination; if any central features, MRI (CT often misses posterior fossa strokes); CTA to evaluate basilar artery |
| Young patient with stroke and neck pain | High suspicion for cervical artery dissection | CTA or MRA head and neck; antithrombotic therapy (antiplatelet or anticoagulation); avoid thrombolysis if dissection confirmed with large extracranial component |
| Stroke mimic suspected but not certain | When in doubt, treat as stroke — risk of untreated stroke outweighs thrombolysis risk in most cases | Thrombolysis complication rate in mimics is low (approximately 1%); MRI can help if available rapidly without delaying treatment |
Troubleshooting: Refractory or Worsening Deficits
Ask These Questions When Patient Is Not Improving or Worsening
- Was recanalization achieved? Check vascular imaging — persistent occlusion may warrant additional intervention
- Is there hemorrhagic transformation? Repeat CT if any deterioration after thrombolysis
- Is there cerebral edema or mass effect? Large infarcts develop edema peaking at 3-5 days; may need osmotic therapy or decompressive surgery
- Is there recurrent stroke or stroke extension? New vascular territory involvement suggests new embolism or propagating thrombus
- Are there metabolic derangements? Hypoxia, hyperglycemia, fever all worsen outcomes — correct aggressively
- Is the diagnosis correct? Reconsider stroke mimics if course is atypical
- Is there seizure activity? Subclinical seizures can cause neurological worsening; consider EEG monitoring
8. Clinical Pearls and Pitfalls
Practical wisdom — learn from successes and avoid common mistakes
Must-Know Clinical Pearls
Last known well, not symptom onset: Always establish when the patient was last definitely at their neurological baseline, not when symptoms were first noticed. For wake-up strokes, last known well is bedtime.
Fingerstick glucose on every stroke alert: Hypoglycemia can perfectly mimic stroke and is rapidly reversible. Check glucose before or during initial assessment — do not wait for laboratory results.
CT can be normal in early ischemic stroke: A normal CT does not exclude ischemic stroke — it excludes hemorrhage. Early ischemic changes may be subtle or absent in the first 6-12 hours. MRI diffusion-weighted imaging is positive within minutes of onset.
Do not let perfect be the enemy of good: When in doubt about stroke versus mimic, treating a mimic with thrombolysis is safer than missing a treatable stroke. Symptomatic hemorrhage rate in mimics is approximately 1%.
Posterior circulation strokes are frequently missed: Vertigo, nausea, and ataxia may be dismissed as peripheral vestibular disease. Use the HINTS examination (Head Impulse, Nystagmus, Test of Skew) — a negative head impulse test with acute vertigo suggests central cause.
The NIHSS underestimates posterior circulation strokes: A patient with basilar occlusion may have a relatively low NIHSS despite devastating brainstem involvement. Do not use NIHSS alone to determine thrombectomy eligibility for posterior circulation.
Atrial fibrillation may be paroxysmal: A single ECG and 24-hour monitoring miss up to 20-30% of paroxysmal atrial fibrillation. Extended cardiac monitoring (14-30 days or implantable loop recorder) should be considered in cryptogenic stroke.
Young stroke requires extended workup: Patients under 50 without traditional risk factors need evaluation for dissection, patent foramen ovale, hypercoagulable states, and rare causes (vasculitis, CADASIL, Fabry disease).
Critical Pitfalls to Avoid
Waiting for laboratory results before thrombolysis: The only test required before thrombolysis is non-contrast CT to exclude hemorrhage. Do not wait for complete blood count, coagulation studies, or metabolic panel unless there is specific clinical concern (known anticoagulation, bleeding disorder, thrombocytopenia).
Dismissing “minor” or “improving” symptoms: A patient whose symptoms are improving but who still has a disabling deficit (cannot use hand, cannot walk) should be treated. “Minor” strokes can cause major disability, and early improvement does not guarantee continued improvement.
Aggressive blood pressure lowering in acute ischemic stroke: Do not lower blood pressure below 185/110 unless giving thrombolysis. The ischemic penumbra depends on collateral perfusion, which is blood pressure dependent. Exception: blood pressure greater than 220/120 or evidence of end-organ damage.
Assuming elderly patients are not thrombectomy candidates: Age alone is not a contraindication to thrombectomy. Trials have shown benefit in patients over 80 years. Functional status before stroke (modified Rankin Scale) is more important than chronological age.
Giving aspirin before excluding hemorrhage: Never give antiplatelet or anticoagulant therapy before neuroimaging has excluded hemorrhage. Aspirin in intracerebral hemorrhage increases bleeding risk.
Delaying transfer for thrombolysis at non-thrombectomy center: “Drip and ship” — give thrombolysis at the presenting hospital while arranging transfer. Do not delay thrombolysis to transfer to a comprehensive stroke center, but do transfer for thrombectomy evaluation.
Premature prognostication in hemorrhagic stroke: Early withdrawal of care in intracerebral hemorrhage leads to self-fulfilling prophecy. Accurate prognosis is difficult in the first 24-48 hours. Provide aggressive supportive care initially and reassess after 48-72 hours.
Missing cervical dissection in young patients: Neck pain or headache preceding or accompanying stroke in a young patient should raise suspicion for carotid or vertebral dissection. Ask specifically about recent trauma, even minor (sports, chiropractic manipulation).
Key Takeaways
- Time is brain: Every minute of untreated large vessel occlusion results in loss of approximately 1.9 million neurons. Door-to-needle time for thrombolysis should be less than 60 minutes.
- Hemorrhage must be excluded before treatment: Non-contrast CT is the only required test before thrombolysis. A normal CT does not exclude ischemic stroke but does exclude hemorrhage.
- Stroke mimics account for 20-30% of stroke alerts: Hypoglycemia, seizure with postictal paralysis, and migraine with aura are common mimics. Always check fingerstick glucose.
- Thrombolysis window is 4.5 hours; thrombectomy window extends to 24 hours: Patients with large vessel occlusion and favorable perfusion imaging may benefit from thrombectomy up to 24 hours from last known well.
- NIHSS quantifies stroke severity but has limitations: It underestimates posterior circulation strokes and does not capture all disabling deficits. Clinical judgment remains essential.
- Complete etiological workup is essential for secondary prevention: Identify the stroke mechanism (large vessel, cardioembolic, small vessel, other, cryptogenic) to guide appropriate antithrombotic therapy and risk factor modification.
- Extended cardiac monitoring detects occult atrial fibrillation: Consider implantable loop recorder in cryptogenic stroke, especially embolic stroke of undetermined source.
- Posterior circulation strokes are dangerous and frequently missed: Isolated vertigo may be the only presenting symptom of posterior inferior cerebellar artery territory stroke. Use HINTS examination and have a low threshold for MRI.
- Secondary prevention reduces recurrence by up to 80%: Antiplatelet or anticoagulant therapy, statin therapy, blood pressure control, and lifestyle modification are all evidence-based interventions.
- Multidisciplinary care improves outcomes: Stroke unit care, early rehabilitation, speech and language therapy, occupational therapy, and physical therapy all contribute to improved functional outcomes.
Quick Reference Algorithm
Systematic Approach to Sudden Focal Neurologic Deficit:
- Activate stroke protocol: Time is brain — mobilize resources immediately
- Establish last known well: Determines treatment eligibility
- Check fingerstick glucose: Exclude hypoglycemia (stroke mimic)
- Perform rapid neurological assessment: NIHSS for severity quantification
- Obtain emergent non-contrast CT: Exclude hemorrhage — only required test before thrombolysis
- Determine thrombolysis eligibility: Within 4.5 hours, no contraindications, blood pressure controlled
- Obtain CTA: Identify large vessel occlusion for thrombectomy consideration
- Administer thrombolysis if eligible: Do not delay for thrombectomy preparation or transfer
- Proceed to thrombectomy if indicated: Large vessel occlusion with favorable imaging up to 24 hours
- Admit to stroke unit: Complete etiological workup, initiate secondary prevention, begin rehabilitation