What causes vasovagal dizziness and how is it treated?

Vasovagal Dizziness: Causes and Treatment

Vasovagal dizziness is primarily caused by a reflex resulting in hypotension and bradycardia, triggered by prolonged standing, emotional stress, pain, or medical procedures, and treatment should focus on patient education, trigger avoidance, physical counterpressure maneuvers, and volume expansion strategies. 1

Causes of Vasovagal Dizziness

Vasovagal dizziness (also called presyncope) is the prodrome of syncope that may include:

• Lightheadedness or dizziness
• Blurry or tunnel vision
• Nausea and sensation of warmth
• Diaphoresis (sweating) and pallor 1

The underlying pathophysiology involves:

1. Neural reflex mechanism: A reflex causing hypotension and bradycardia
2. Triggering factors:
   • Prolonged standing
   • Emotional stress or fear
   • Pain
   • Medical procedures (e.g., venipuncture)
   • Hot, crowded environments
   • Volume depletion 1

Treatment Approach

Immediate Management During an Episode

1. Safe positioning:

   • Maintain or assume a safe position such as assisted sitting or lying down
   • Elevate legs if possible 1

2. Physical counterpressure maneuvers (PCMs):

   • Lower-body PCMs (preferred):
     • Leg crossing with tensing of leg, abdominal, and buttock muscles
     • Squatting with muscle tensing
   • Upper-body PCMs:
     • Arm tensing (gripping opposing hands and pulling)
     • Isometric handgrip (clenching fist with maximum contraction)
     • Neck flexion (touching chin to chest) 1

3. Activate emergency services if:

   • No improvement within 1-2 minutes
   • Syncope occurs
   • Symptoms worsen or recur
   • Symptoms of heart attack or stroke accompany presyncope 1

Long-Term Management

1. Patient education and reassurance:

   • Explain the benign nature of the condition
   • Review typical prodromal symptoms
   • Teach recognition of impending episodes 1, 2

2. Trigger avoidance:

   • Avoid prolonged standing
   • Minimize exposure to hot, crowded environments
   • Prevent volume depletion
   • Avoid venipuncture when possible
   • Discontinue or reduce vasodilator medications if applicable 1, 2

3. Volume expansion strategies:

   • Increased dietary salt intake (unless contraindicated by hypertension)
   • Adequate fluid intake (2-2.5 liters per day)
   • Consider "sport" drinks or salt tablets
   • Head-up tilt sleeping (>10°) 1, 2, 3

4. Physical conditioning:

   • Moderate exercise training
   • Tilt training (progressively prolonged periods of enforced upright posture) for highly motivated patients 1

5. Pharmacological options (for refractory cases):

   • Midodrine: First-line therapy for patients with frequent episodes or brief/no prodromes
     • Avoid in patients with hypertension, heart failure, or urinary retention 1, 3
   • Fludrocortisone: Low dose (0.1-0.2 mg daily) for refractory cases 1, 2
   • Not recommended: Beta-blockers (may worsen bradycardia in cardioinhibitory cases) 1, 2

Special Considerations

• High-risk settings: More aggressive treatment for patients in high-risk occupations (commercial vehicle drivers, machine operators, pilots) 1, 2

• Single episode: Treatment not necessary for patients who have experienced only one episode and are not in a high-risk setting 1

• Elderly patients: More cautious approach to volume expansion if cardiovascular comorbidities exist 2

• Cardiac pacing: Reserved for cardioinhibitory or mixed carotid sinus syndrome, or cardioinhibitory vasovagal syncope with >5 attacks per year or severe physical injury and age >40 1

Treatment Algorithm

1. First-line approach (for all patients):

   • Patient education and reassurance
   • Trigger avoidance
   • Teaching physical counterpressure maneuvers
   • Volume expansion (increased salt and fluid intake)

2. Second-line approach (for patients with frequent episodes):

   • Midodrine (if no contraindications)
   • Tilt training (for motivated patients)

3. Third-line approach (for refractory cases):

   • Fludrocortisone
   • Consider cardiac pacing only for specific indications

Pitfalls and Caveats

• Do not routinely treat with vestibular suppressant medications (antihistamines or benzodiazepines) 1
• Beta-blockers may worsen symptoms in cardioinhibitory cases 1, 2
• Always rule out cardiac causes of syncope before assuming vasovagal etiology
• Physical counterpressure maneuvers are not recommended when symptoms of heart attack or stroke accompany presyncope 1
• Recognize that vasovagal syncope is generally benign but can lead to injuries from falls 1, 4