What are the symptoms of Vertebrobasilar (VBI) insufficiency?

Symptoms of Vertebrobasilar Insufficiency (VBI)

Vertebrobasilar insufficiency presents with dizziness, vertigo, diplopia, perioral numbness, blurred vision, tinnitus, ataxia, bilateral sensory deficits, and syncope as its primary symptoms. 1

Primary Symptoms

• Dizziness and vertigo - Most common manifestations, often transient and may precede stroke by weeks or months 2, 1
• Visual disturbances - Including:
  • Diplopia (double vision)
  • Blurred vision
  • Bilateral vision loss in severe cases
• Sensory symptoms:
  • Perioral numbness
  • Bilateral sensory deficits
• Balance problems:
  • Ataxia
  • Imbalance
• Other neurological symptoms:
  • Tinnitus
  • Syncope (fainting)
  • Weakness in both sides of the body 1, 3

Key Distinguishing Features

The attacks of vertigo in VBI typically:

• Last less than 30 minutes 2
• Have no associated hearing loss
• Are often provoked by head turning or extension 1
• Resolve with position change 1
• Are associated with other brainstem neurological deficits 1

Differentiating from BPPV

VBI can be distinguished from Benign Paroxysmal Positional Vertigo (BPPV) by:

1. Presence of additional neurological signs
2. Type of nystagmus (typically gaze-evoked in VBI vs. rotational in BPPV)
3. Severity of postural instability
4. Nystagmus in VBI does not fatigue
5. Nystagmus is not easily suppressed by gaze fixation 2

Clinical Presentation Patterns

Isolated episodes of dizziness may be the initial and only symptom of VBI, potentially preceding a stroke in the vertebrobasilar artery by weeks or months 2, 4. Research suggests that isolated dizziness in VBI likely results from transient ischemia in territories supplied by the anterior inferior cerebellar artery 4.

Pathophysiology and Triggers

Symptoms are commonly triggered by:

• Head turning (particularly when vertebral artery compression occurs from osteophytes) 2
• Mechanical compression from overgrowth of the transverse process of a vertebra 1
• Atherosclerotic narrowing (most common cause) 1, 3
• Blood clots forming in or traveling to the vertebral and basilar arteries 1

Clinical Pitfalls to Avoid

1. Misdiagnosis: VBI symptoms can mimic other conditions like BPPV, vestibular neuritis, Meniere's disease, and cardiac arrhythmias 2, 1
2. Incomplete evaluation: Failure to recognize that isolated dizziness can be the sole presenting symptom of VBI 2, 4
3. Delayed diagnosis: Not recognizing that VBI symptoms may precede a stroke by weeks or months 2
4. Inadequate imaging: Relying solely on ultrasound, which has lower sensitivity (70%) compared to CTA/MRA (94% sensitivity, 95% specificity) 1

When to Suspect VBI

Consider VBI when:

• Vertigo occurs with other neurological symptoms
• Symptoms are provoked by head turning
• Patient has vascular risk factors
• Nystagmus does not fatigue and is not suppressed by fixation
• Patient fails to respond to treatments for peripheral vestibular disorders 2, 1

The presence of multiple neurological symptoms affecting the posterior circulation territory strongly suggests VBI rather than a peripheral vestibular disorder. Prompt recognition of these symptoms is crucial as they may herald an impending stroke in the vertebrobasilar territory.