Are all stroke symptoms unilateral?

Are All Stroke Symptoms Unilateral?

No, not all stroke symptoms are unilateral, though unilateral symptoms such as weakness and sensory changes are common and considered high-risk indicators of stroke.

Common Stroke Presentations

Unilateral Symptoms

• Unilateral weakness (face, arm, and/or leg) is one of the most recognized and highest risk symptoms of stroke 1
• Unilateral sensory changes (numbness, tingling) affecting one side of the body 1
• Unilateral visual field defects (hemianopia) affecting vision on one side 1

Bilateral or Non-Lateralizing Symptoms

• Speech disturbances (aphasia, dysarthria) can occur without lateralizing motor symptoms 1
• Binocular diplopia (double vision) 1
• Ataxia (coordination problems) 1
• Vertigo with other brainstem symptoms 1
• Bilateral hearing loss (rare, typically from vertebrobasilar strokes) 1
• Dysarthria and dysphagia can occur without lateralizing weakness 1

Anatomical Considerations

Vascular Territory Correlation

• Unilateral symptoms typically result from contralateral hemisphere lesions due to the crossing of motor and sensory pathways 2, 3
• Bilateral symptoms may occur with:
  • Vertebrobasilar circulation strokes affecting the brainstem 1
  • Bilateral cortical strokes (rare) 1
  • Large territory strokes affecting multiple regions 3

Rare Exceptions

• In extremely rare cases, ipsilateral weakness can occur following stroke, usually in patients with previous brain injuries where neuroplasticity has led to reorganization of motor pathways 4

Clinical Significance and Recognition

Stroke Risk Stratification

The Canadian Stroke Best Practice Guidelines categorize stroke risk based on symptom presentation 1:

• Very high risk (within 48 hours):

  • Transient, fluctuating, or persistent unilateral weakness
  • Transient, fluctuating, or persistent speech disturbance

• High risk (48 hours to 2 weeks):

  • Same symptoms as above but with longer time from onset

• Moderate risk (48 hours to 2 weeks):

  • Symptoms without unilateral motor weakness or speech disturbance (e.g., sensory symptoms, visual changes, ataxia)

Recognition Challenges

• Right hemispheric strokes may be less frequently recognized than left hemispheric strokes 5
• This recognition disparity may be due to:
  • Left hemisphere strokes often causing more obvious language deficits
  • Right hemisphere symptoms sometimes being more subtle or misattributed to other causes
  • Patient awareness of symptoms differing between hemispheres

Clinical Implications

Diagnostic Approach

• All patients with suspected stroke should receive urgent brain imaging (CT or MRI) and vascular imaging 1, 6
• The presence of non-unilateral symptoms should not delay stroke evaluation, as these may still represent stroke 1, 6

Treatment Considerations

• Both unilateral and non-unilateral stroke symptoms may qualify for acute interventions like thrombolysis or thrombectomy when appropriate 6
• Rehabilitation approaches may differ based on symptom presentation, with specialized approaches needed for certain deficits like unilateral spatial neglect 1

Key Pitfalls to Avoid

• Assuming bilateral symptoms exclude stroke - vertebrobasilar strokes can present with bilateral or non-lateralizing symptoms 1
• Overlooking right hemisphere strokes - these may present with less obvious symptoms but still require urgent evaluation 5
• Delaying evaluation of non-classic symptoms - symptoms without unilateral weakness still warrant urgent assessment 1
• Failing to recognize rare presentations - unusual presentations like bilateral hearing loss can rarely be stroke symptoms 1

In summary, while unilateral symptoms (particularly weakness) are classic and high-risk indicators of stroke, clinicians must remain vigilant for the full spectrum of stroke presentations, including those that are bilateral or non-lateralizing.