What is Vertebral Basilar Insufficiency (VBI)?

Vertebral Basilar Insufficiency (VBI) in Layman's Terms

Vertebrobasilar insufficiency (VBI) is a condition where there is reduced blood flow to the back part of your brain due to narrowing or blockage of the vertebral and basilar arteries, causing temporary episodes of dizziness, vertigo, and other neurological symptoms that are often triggered by specific head movements. 1

What Causes VBI?

Vertebrobasilar insufficiency affects the posterior circulation of your brain, which is supplied by the vertebral and basilar arteries. These blood vessels provide oxygen and nutrients to critical brain structures including:

• The brainstem (controls basic life functions)
• The cerebellum (coordinates movement and balance)
• Parts of the occipital lobes (vision centers)

Common causes include:

• Atherosclerosis - The most frequent cause, where fatty deposits narrow the arteries 2
• Mechanical compression - When the vertebral arteries are compressed by:
  • Bone spurs (osteophytes) in the neck 3
  • Head rotation or extension that pinches the arteries 4
  • Overgrowth of the transverse process of a vertebra 2
• Blood clots - Forming in or traveling to these vessels
• Dissection - Tearing of the arterial wall 1

Common Symptoms

VBI typically causes transient (temporary) symptoms that may include:

• Dizziness and vertigo (spinning sensation)
• Headaches
• Double vision (diplopia)
• Blurred vision or temporary blindness
• Numbness around the mouth (perioral numbness)
• Ringing in the ears (tinnitus)
• Poor coordination and unsteady walking (ataxia)
• Weakness on both sides of the body
• Fainting or near-fainting (syncope) 2, 5

What makes VBI distinctive is that symptoms:

• Often occur when turning or extending the head
• Typically resolve when returning to a normal head position
• May be accompanied by other neurological symptoms 1

How VBI Is Diagnosed

Diagnosing VBI involves several approaches:

1. Medical history - Focusing on symptoms triggered by head position changes

2. Imaging tests:

   • MRA (Magnetic Resonance Angiography) - Recommended as first-line imaging with 94% sensitivity and 95% specificity 1
   • CTA (Computed Tomography Angiography) - Also highly effective for visualizing the vertebral arteries 2
   • Transcranial Doppler ultrasound - Can detect blood flow changes during head movements, though less sensitive (70%) than MRA/CTA 1, 6

3. Positional testing - Observing symptoms when the head is placed in different positions 6

How VBI Differs From Other Conditions

VBI is often confused with:

• Benign Paroxysmal Positional Vertigo (BPPV) - Both cause positional dizziness, but BPPV typically shows characteristic nystagmus (eye movements) on the Dix-Hallpike maneuver and doesn't have other neurological symptoms 2
• Migraine-associated vertigo - Includes headache and sensitivity to light/sound 2
• Inner ear disorders - Usually don't have other neurological symptoms
• Cardiac problems - Such as arrhythmias that can cause dizziness 2

Treatment Options

Treatment for VBI focuses on:

1. Medical management:

   • Antiplatelet therapy - Aspirin plus dipyridamole to prevent blood clots 1
   • Risk factor modification - Controlling blood pressure, cholesterol, diabetes, and smoking cessation 1

2. For severe cases:

   • Revascularization - Surgical procedures to improve blood flow 7
   • Anticoagulation - For acute cases with blood clots 1

3. Conservative approaches:

   • Avoiding extreme head positions that trigger symptoms 4
   • Physical therapy to improve neck mobility without compromising blood flow

When to Seek Immediate Medical Attention

Seek emergency care if you experience:

• Sudden severe dizziness with other neurological symptoms
• Vision changes
• Difficulty speaking
• Weakness on one or both sides of the body
• Loss of coordination

These could indicate a stroke rather than temporary VBI symptoms and require immediate medical attention.