What type of stroke causes dizziness?

Posterior Circulation Stroke is the Primary Cause of Dizziness in Stroke

Posterior circulation strokes involving the vertebrobasilar system are the main type of stroke that causes dizziness or vertigo. These strokes account for approximately 20% of all strokes and represent a significant cause of acute vestibular syndrome 1.

Vertebrobasilar System and Dizziness

Anatomy and Pathophysiology

• The vertebral arteries arise from the subclavian arteries (in 95% of people) and have four segments (V₁-V₄) 1
• Atherosclerotic stenosis commonly affects the first portion of the vertebral arteries or extends from plaques at their origin 1
• Vertebrobasilar insufficiency can cause symptoms through:
  • Compromised blood flow to the brainstem and cerebellum
  • Atheroembolism causing brainstem or cerebellar infarction 1

Clinical Presentation

Posterior circulation strokes present with distinctive symptoms:

• Common vestibular symptoms:

  • Dizziness/vertigo (most common symptom) 2
  • Imbalance and ataxia
  • Nystagmus

• Associated symptoms that may occur:

  • Diplopia (double vision)
  • Cranial nerve deficits
  • Visual field loss
  • Slurred speech
  • Unilateral extremity weakness 1
  • Perioral numbness
  • Tinnitus 1

Isolated Vestibular Syndromes in Stroke

Isolated Vertigo in Posterior Circulation Stroke

• Up to 25% of Acute Vestibular Syndrome cases may be due to stroke 3
• Approximately 11% of patients with isolated cerebellar infarction present with isolated vertigo, nystagmus, and postural unsteadiness that mimics peripheral vestibular disorders 4
• Small infarcts in specific areas can cause isolated vertigo without other neurological symptoms:
  • Dorsal brainstem (containing vestibular nucleus)
  • Cerebellum (flocculus, tonsil, nodulus)
  • Cerebellar peduncle 5

Cortical Involvement

• The prevalence of vertigo in acute cortical strokes is approximately 9% 6
• Right hemispheric strokes may be more likely to cause vestibular symptoms than left hemispheric strokes 6

Diagnostic Approach for Suspected Stroke-Related Vertigo

Key Clinical Assessments

• HINTS examination (Head Impulse, Nystagmus, Test of Skew) is highly sensitive for detecting stroke in acute vestibular syndrome 3

  • An abnormal HINTS exam strongly suggests central vertigo
  • Has 100% sensitivity compared to early MRI (46%) when performed by trained practitioners

• VAIN triad (Vertigo-Ataxia, Incessant, or Non-positional) has 100% sensitivity for central vertigo 3

• Warning features of stroke-related vertigo:

  • Sudden onset
  • Constant symptoms not changing with head movement
  • Gait instability
  • Subtle neurological findings 3

Imaging Recommendations

• MRI brain is the preferred imaging modality for suspected central vertigo 3
  • CT head is often inadequate and may miss posterior fossa strokes
  • MRA Head and Neck is indicated when vertebrobasilar insufficiency is suspected

Management Considerations

• Patients with posterior circulation TIAs presenting with dizziness have a high risk of recurrent events 7
• Management includes:
  • Antiplatelet therapy
  • Statin use
  • Vascular risk factor modification 7
  • Evaluation of both intracranial and extracranial vertebral arteries

Clinical Pearls and Pitfalls

• Pitfall: Posterior circulation strokes can mimic peripheral vestibular disorders, leading to misdiagnosis
• Pitfall: The NIHSS has limitations in posterior circulation strokes as it focuses on limb and speech impairments with less emphasis on cranial nerve lesions 1
• Pearl: Patients with posterior circulation stroke can have an NIHSS score of 0, presenting only with headache, vertigo, and nausea 1
• Pearl: One-third to two-thirds of patients with posterior circulation stroke may lack focal neurologic signs 3

Remember that dizziness is the most common symptom of transient ischemia within the vertebrobasilar system, and isolated attacks of vertigo can occur even without other neurological symptoms 2. Maintain a high index of clinical suspicion, especially in patients with vascular risk factors.