Clinical Signs of Acute Stroke
The cardinal signs of acute stroke are sudden unilateral weakness (face, arm, or leg), speech disturbance, and facial droop—captured by the FAST mnemonic (Face, Arm, Speech, Time)—which are present in 88% of all strokes and TIAs 1.
Primary Stroke Signs (Highest Recognition Priority)
The most critical signs to recognize immediately include:
- Unilateral limb weakness (82% of cases) - affecting face, arm, and/or leg on one side 2
- Speech deficits (24-48% of cases) - including dysarthria (slurred speech) or aphasia (language disturbance) 2, 3
- Facial weakness - unilateral facial droop or asymmetry 1
These three signs form the core of the FAST assessment and should trigger immediate 9-1-1 activation 1, 2.
Additional Common Signs
Beyond the FAST criteria, clinicians should recognize:
Motor and Sensory Signs:
- Central facial or lingual palsy (61% of cases) 4
- Unilateral sensory loss or paresthesias (31-45% of cases) 3, 4
- Ataxia or gait disturbance (30% of cases) 4
Visual Signs:
- Hemianopia (visual field loss) - 15% of cases 5
- Diplopia (double vision) - 5-9% of cases 5, 3
- Monocular vision loss 2
Altered Mental Status:
- Nonalert mental status or decreased level of consciousness 6
- This finding increases likelihood of cortical stroke significantly (OR = 4.50) 6
Posterior Circulation Stroke Signs
Posterior circulation strokes present differently and require heightened awareness 5:
- Gait ataxia (70% in cerebellar strokes) 5
- Vertigo/dizziness (41-50% of cases) 5
- Dysarthria (48% of cases) 5
- Nausea/vomiting (41% of cases) 5
- Binocular diplopia, dysphagia 2
Critical caveat: Isolated vertigo is rare (only 1.4% of cases), and crossed paralysis occurs in less than 3% 4. The complexity of posterior circulation presentations makes diagnosis challenging, but predominant brainstem symptoms should raise suspicion 4.
Hemorrhagic Stroke Distinguishing Features
While imaging is required for definitive differentiation, certain signs suggest hemorrhagic rather than ischemic stroke:
- Severe sudden headache (56% vs 22% in ischemic stroke) 3
- Convulsions (11% vs 3% in ischemic stroke) 3
- Altered consciousness more prominent 7
High-Risk Presentations Requiring Immediate Action
Patients presenting within 48 hours with any of these signs are at VERY HIGH risk and require immediate ED transport with stroke capability 2:
- Transient, fluctuating, or persistent unilateral weakness
- Any language/speech disturbance
- Hemibody sensory symptoms
- Visual field defects
- Posterior circulation symptoms (diplopia, dysarthria, dysphagia, ataxia)
Important Clinical Pitfalls
Absence of cortical signs does not exclude cortical stroke: 19.4% of cortical strokes present without obvious cortical deficits like aphasia, neglect, or hemianopia on initial examination 6. This underscores why any sudden focal neurologic deficit warrants stroke evaluation.
Risk factors that increase likelihood of cortical stroke include atrial fibrillation (OR = 4.77), recent hospitalization (OR = 4.51), and possible cardioembolic conditions 6. These should heighten suspicion even when cortical signs are subtle.
The "5 Suddens" remain valid: sudden weakness, sudden speech difficulty, sudden visual loss, sudden dizziness, and sudden severe headache 1. The abrupt onset is the hallmark—awakening with or experiencing sudden focal deficits distinguishes stroke from mimics 7.
Stroke Mimics to Consider
The most common conditions mimicking stroke are seizure, conversion disorder, migraine with aura, and hypoglycemia 7. However, when stroke is suspected, the priority is immediate activation of emergency services rather than attempting to exclude mimics in the field or primary care setting 1, 2.