Stroke 

Definition

Stroke is a sudden onset of focal or global neurological deficit lasting >24 hours or leading to death, due to a vascular cause.

Evidence of brain, spinal cord, or retinal infarction/hemorrhage due to vascular pathology.

• 80–85% → Ischemic
• 15–20% → Hemorrhagic

 Types of Stroke

Ischemic Stroke (Most common)

• Thrombosis (atherosclerosis)
• Embolism (cardioembolic → AF most common)
• Lacunar infarcts (small vessel disease)

 TOAST(Trial of Org 10172 in Acute Stroke Treatment) Classification

Hemorrhagic Stroke

 Types

• Intracerebral hemorrhage (ICH)
• Subarachnoid hemorrhage (SAH)

 Causes

• HTN (most common ICH)
• Amyloid angiopathy (elderly)
• Aneurysm rupture (SAH)
• AV malformations
• Anticoagulants

DIFFERENTIATING STROKE TYPES CLINICALLY

BUT: Clinical differentiation is unreliable → Imaging mandatory

 STROKE MIMICS 

Clinical Features

• Abrupt onset
• Focal deficits (not diffuse, unlike metabolic encephalopathy)
• Negative symptoms predominate (loss of function > positive phenomena)

 NEGATIVE vs POSITIVE SYMPTOMS 

BEFAST CRITERIA (STROKE RECOGNITION TOOL)

CORE CLINICAL FEATURES 

 A. MOTOR DEFICITS

Hemiparesis / Hemiplegia

• Most common presentation
• Contralateral weakness (due to corticospinal tract involvement)
• Distribution:
• Face + arm > leg → MCA stroke
• Leg > arm → ACA stroke

UMN signs

• Hyperreflexia
• Spasticity (late)
• Babinski positive

Facial weakness

• UMN facial palsy
• Lower face affected
• Forehead spared

 B. SENSORY DEFICITS

• Contralateral:
• Loss of pain, temperature, touch
• Cortical sensory deficits:
• Astereognosis
• Agraphesthesia
• Pure sensory stroke → classically thalamic infarct

 C. SPEECH & LANGUAGE (DOMINANT HEMISPHERE)

Aphasia (dominant hemisphere, usually left)

Dysarthria

• Slurred speech (motor problem, not language)

D. VISUAL DEFICITS

• Homonymous hemianopia (most common)
• Quadrantanopia:
• “Pie in the sky” → temporal lobe
• “Pie on the floor” → parietal lobe
• Cortical blindness → bilateral occipital

E. COORDINATION & CEREBELLAR SIGNS

• Ataxia
• Dysmetria
• Intention tremor
• Nystagmus
• Vertigo (posterior circulation stroke)

F. CRANIAL NERVE DEFICITS (BRAINSTEM STROKE)

“Crossed findings” 

• Ipsilateral cranial nerve deficit
• Contralateral body weakness/sensory loss

Examples

• Diplopia
• Dysphagia
• Dysarthria
• Facial numbness

 G. COGNITIVE & HIGHER FUNCTION DEFICITS

• Neglect (non-dominant parietal lobe)
• Apraxia
• Agnosia
• Memory impairment (temporal lobe)

 FEATURES BASED ON VASCULAR TERRITORY 

A. Middle Cerebral Artery (MCA)

7

• Face + arm weakness > leg
• Aphasia (dominant)
• Neglect (non-dominant)
• Homonymous hemianopia

 B. Anterior Cerebral Artery (ACA)

6

• Leg > arm weakness
• Abulia (lack of initiative)
• Urinary incontinence

C. Posterior Cerebral Artery (PCA)

6

• Visual field defects
• Cortical blindness
• Memory deficits
• Alexia without agraphia

D. LACUNAR STROKES

• Pure motor stroke
• Pure sensory stroke
• Ataxic hemiparesis
• Dysarthria–clumsy hand

E. POSTERIOR CIRCULATION STROKE

• Vertigo
• Ataxia
• Diplopia
• Dysphagia
• Altered consciousness

WARNING SYMPTOMS (TIA / EVOLVING STROKE)

• Transient weakness
• Speech difficulty
• Amaurosis fugax (monocular vision loss)

RED FLAGS  SUGGESTING HEMORRHAGIC STROKE

• Severe headache (“thunderclap”)
• Vomiting
• Rapid decline in consciousness
• Seizures

Diagnosis 

 Only 2 tests are truly mandatory and should NOT delay therapy:

1. NCCT Head
2. Blood Glucose

✔ Others should not delay thrombolysis unless specific suspicion exists (as per American Heart Association / American Stroke Association)

1. Imaging (First step)

 FIRST-LINE: Non-Contrast CT (NCCT Brain)

• Exclude hemorrhage (absolute contraindication to thrombolysis)
• Detect early ischemic changes
• Assess extent of infarction

NCCT FINDINGS

 Early Ischemic Signs (subtle, within hours)

• Loss of gray-white differentiation
• Loss of insular ribbon
• Obscuration of lentiform nucleus
• Sulcal effacement

 Hyperdense Artery Sign

• e.g., Hyperdense MCA sign
• Indicates large vessel occlusion (LVO)

 2. ASPECTS SCORE 

Used on NCCT to quantify early ischemic changes in MCA territory.

• ASPECTS ≥6 → thrombectomy benefit

3. CT ANGIOGRAPHY (CTA)

• Detect large vessel occlusion (LVO)
• Plan thrombectomy

CTA Findings

• MCA, ICA, basilar artery occlusion
• Tandem lesions
• Collateral circulation

 Role:

• Mandatory before mechanical thrombectomy
• Should not delay thrombolysis if already eligible

4. CT PERFUSION (CTP)

Differentiates:

• Infarct core (irreversible)
• Penumbra (salvageable tissue)

Parameters:

CTP Maps Mismatch Concept: Mismatch

• Penumbra > Core → salvageable brain

Used in:

• Extended window thrombectomy (6–24 hrs)
• Trials:
• DAWN trial
• DEFUSE 3 trial

5. MRI IN STROKE

• 
  DWI positivity = earliest sign of infarction
• Sensitivity: >95% for acute ischemic stroke

 Pathophysiology:

• Energy failure → Na⁺/K⁺ pump failure → cytotoxic edema → ↓ diffusion

 DWI–FLAIR Mismatch (Wake-Up Stroke)

• DWI positive + FLAIR negative → stroke <4.5 hours

Clinical Importance:

• Basis of WAKE-UP trial
• Allows IV thrombolysis even when onset unknown

 MRI for Penumbra (Tissue at Risk)

PWI–DWI Mismatch Concept

• DWI lesion = infarct core
• PWI deficit > DWI lesion = salvageable penumbra

Clinical Use:

• Selection for thrombectomy beyond 6 hours
• Based on trials like:
• DAWN trial
• DEFUSE 3 trial
• MRI (or CT perfusion) used for extended window (6–24 hr) thrombectomy selection