What is the best initial diagnostic and treatment approach to localize and lateralize a stroke in an adult patient with potential risk factors such as hypertension or diabetes?

Localizing and Lateralizing Stroke: Diagnostic Approach

Immediately perform non-contrast CT or MRI brain imaging within 30 minutes of arrival to definitively localize the stroke lesion, as clinical examination alone is insufficient for accurate anatomic localization. 1

Immediate Diagnostic Protocol

Activate the stroke protocol immediately upon suspicion, regardless of clinical uncertainty, as objective testing is required to confirm and localize cerebrovascular events. 1

Time-Critical Initial Assessment (Within 10 Minutes)

• Establish exact time of symptom onset - defined as when the patient was last known to be at baseline or symptom-free, as this determines treatment eligibility 2
• Apply FAST assessment (Face, Arm, Speech, Time) to rapidly identify focal neurological deficits 1
• Perform NIHSS (National Institutes of Health Stroke Scale) to quantify stroke severity and provide prognostic information that influences acute treatment decisions 2

Neurological Examination for Localization

Eight clinical features independently predict stroke and assist with localization: 3

• Exact time of onset (not gradual or vague) 3
• Definite focal symptoms (not diffuse or non-specific) 3
• Abnormal vascular findings on examination 3
• Presence of objective neurological signs (not just subjective complaints) 3
• Ability to lateralize signs to left or right hemisphere - this is the key to lateralization 3
• Ability to determine clinical stroke subclassification (anterior vs. posterior circulation) 3
• Absence of cognitive impairment alone (which suggests mimic) 3
• Absence of abnormal signs in other organ systems (which suggests alternative diagnosis) 3

Clinical localization skills enable rapid identification of affected arterial territories by associating presenting disabilities with specific brain regions. 4

Essential Imaging for Anatomic Localization (Within 30 Minutes)

Brain imaging is mandatory and must not be delayed - it is the only definitive method to localize the lesion and differentiate ischemic from hemorrhagic stroke. 2, 1

Primary Imaging

• Non-contrast CT scan remains the most practical initial brain imaging at most institutions for emergency stroke evaluation 2
• MRI with diffusion-weighted imaging provides superior sensitivity for acute ischemia and precise anatomic localization, though less widely available emergently 2
• A physician skilled in neuroimaging interpretation must evaluate the scan immediately for early ischemic changes and hemorrhage 2

Vascular Imaging for Localization

CT angiography or MR angiography from aortic arch to vertex within 24 hours to identify the specific occluded vessel and determine anterior vs. posterior circulation involvement 5

• Transcranial Doppler ultrasonography can detect intracranial vessel occlusions and monitor thrombolysis effects 2
• Carotid duplex sonography identifies extracranial large vessel disease 2
• Vascular imaging is necessary for endovascular interventions but should not delay intravenous thrombolysis in patients presenting within 3 hours 2

Lateralization: Right vs. Left Hemisphere

The ability to lateralize neurological signs to the left or right side of the brain is one of the strongest clinical predictors distinguishing true stroke from mimics. 3

Key Lateralizing Features

• Unilateral motor weakness (face, arm, leg) indicates contralateral hemisphere involvement 4
• Unilateral sensory loss localizes to contralateral hemisphere 4
• Visual field defects (homonymous hemianopia) indicate contralateral occipital or optic radiation involvement 4
• Language dysfunction (aphasia) typically indicates left (dominant) hemisphere stroke in right-handed patients 3
• Spatial neglect and perceptual deficits more commonly indicate right (non-dominant) hemisphere involvement 6

Right hemisphere strokes demonstrate faster rehabilitation progression and better ambulation outcomes compared to left hemisphere strokes. 6

Mandatory Ancillary Tests for Complete Evaluation

Complete the following tests within 60 minutes of arrival to exclude stroke mimics and identify stroke mechanism: 2

• 12-lead ECG immediately to detect atrial fibrillation (5-fold stroke risk) and acute myocardial infarction 2, 5
• Blood glucose immediately to exclude hypoglycemia, a common stroke mimic presenting with focal deficits 1
• Complete blood count, electrolytes, renal function 1
• Coagulation studies (PT/INR, aPTT) before any antithrombotic therapy 1
• Cardiac enzymes (troponin) as acute MI can cause stroke and stroke can cause myocardial ischemia 2, 5
• Continuous cardiac monitoring for ≥24 hours to detect paroxysmal atrial fibrillation 5

Critical Pitfalls in Localization

Do not rely on clinical examination alone to localize stroke - imaging confirmation is mandatory. 1

• Do not assume stroke type or location based on severity alone - substantial overlap exists between presentations 1
• Do not delay imaging to obtain additional history - the 30-minute door-to-imaging target takes priority 1
• Do not administer thrombolytics until hemorrhage is definitively excluded by imaging, regardless of how typical the clinical presentation appears 1
• Do not skip vascular imaging in patients being considered for endovascular therapy - knowing the specific occluded vessel is essential 2

Stroke Mimics That Confound Localization

Common conditions presenting with focal neurological deficits that mimic stroke localization: 1

• Hypoglycemia - check glucose immediately in all patients 1
• Post-ictal Todd's paralysis following seizure 1
• Complicated migraine with aura causing transient focal symptoms 1
• Subdural hematoma or brain tumor causing progressive deficits 1
• Metabolic encephalopathy (hepatic, uremic) 1

Risk Factor Context for Patients with Hypertension and Diabetes

Hypertension increases stroke risk 2-fold, while diabetes increases risk 2.5-4.1 fold in men and 3.6-5.8 fold in women. 2, 7

• These patients require the same immediate diagnostic approach - do not delay imaging or alter the localization protocol based on risk factors alone 2
• Blood pressure management differs in acute stroke - do not aggressively lower BP unless >220/120 mmHg (or >185/110 if considering thrombolysis) 2
• Hyperglycemia in acute stroke worsens outcomes - treat glucose >200 mg/dL targeting 140-180 mg/dL 2