How do you diagnose and treat peripheral vertigo, including identifying the affected canal and laterality?

Diagnosis of Laterality and Canal Identification in Peripheral Vertigo

The diagnosis of peripheral vertigo requires systematic positional testing to identify both the affected canal and laterality, with the Dix-Hallpike maneuver for posterior canal BPPV and the supine roll test for lateral canal BPPV being the gold standard diagnostic procedures. 1

Diagnostic Algorithm for Canal Identification

Step 1: Posterior Canal Assessment (Most Common)

• Perform the Dix-Hallpike maneuver by bringing the patient from upright to supine position with the head turned 45° to one side and neck extended 20° 1
• Positive diagnosis when vertigo with torsional, upbeating nystagmus is provoked with:
  • Latency period (typically 5-20 seconds)
  • Nystagmus and vertigo resolving within 60 seconds 1
• If initial test is negative, repeat for the opposite side 1
• Sensitivity of 82% and specificity of 71% for posterior canal BPPV 1

Step 2: Lateral Canal Assessment

• If posterior canal testing is negative or if horizontal nystagmus is observed, perform the supine roll test 1
• Position patient supine with head in neutral position, then quickly rotate head 90° to one side 1
• Return to neutral position after nystagmus subsides, then rotate 90° to opposite side 1
• Observe for two possible nystagmus patterns:
  • Geotropic: Nystagmus beats toward the ground (more common)
  • Apogeotropic: Nystagmus beats away from the ground 1

Determining Laterality (Affected Ear)

For Posterior Canal BPPV

• The affected ear is the one facing downward during the positive Dix-Hallpike maneuver 1

For Lateral Canal BPPV (Multiple Methods)

• Supine roll test intensity comparison:

  • Geotropic form: The side with stronger nystagmus is the affected ear
  • Apogeotropic form: The side opposite the stronger nystagmus is the affected ear 1

• Lying-down nystagmus test:

  • Move patient from sitting to straight supine position
  • Geotropic: Nystagmus beats away from affected ear
  • Apogeotropic: Nystagmus beats toward affected ear 1

• Head pitch test (in supine position):

  • Patient sits up with head bent down
  • Geotropic: Nystagmus usually beats toward affected ear
  • Apogeotropic: Nystagmus beats away from affected ear 1

• Bow and lean test:

  • Observe nystagmus when patient bends head forward (bowing) and backward (leaning)
  • Geotropic form:
    • Bowing: Nystagmus beats toward affected ear
    • Leaning: Nystagmus beats away from affected ear
  • Apogeotropic form:
    • Bowing: Nystagmus beats away from affected ear
    • Leaning: Nystagmus beats toward affected ear 1

Treatment Based on Canal Identification

Posterior Canal BPPV

• Treat with canalith repositioning procedure (Epley maneuver) 1, 2
• Success rate of 70-90% with proper technique 3

Lateral Canal BPPV

• Use either:
  • Rolling maneuver of 270-360° ("barbecue maneuver")
  • "Forced prolonged position" technique
  • Gufoni maneuver 3, 2
• Success rate approximately 70% after a few maneuvers 3

Important Clinical Considerations

• Repeated testing may be necessary - if initial Dix-Hallpike is negative, repeating the test can increase diagnostic yield 4, 5
• BPPV fatigue phenomenon: Repeated testing may cause diminished response that typically resolves within 30 minutes 2
• Differentiate BPPV from other causes of vertigo including Ménière's disease, vestibular neuritis, vestibular migraine, and central causes 1
• Avoid routine use of vestibular suppressant medications like meclizine for BPPV, as they may delay recovery and cause drowsiness 1, 6
• Patients with suspected horizontal or anterior canal BPPV should be examined by a neurologist to rule out central causes, particularly when downbeat nystagmus is present 3

Common Pitfalls to Avoid

• Failing to repeat the Dix-Hallpike test if initially negative 5
• Not testing for lateral canal BPPV when posterior canal testing is negative 1, 5
• Misinterpreting apogeotropic nystagmus (less common form) 1
• Overlooking conversion from posterior to lateral canal BPPV during treatment (canal switch) 1
• Recommending unnecessary post-procedural restrictions after repositioning maneuvers 1
• Ordering unnecessary imaging or vestibular testing when diagnostic criteria for BPPV are met 1

By systematically following this diagnostic approach, clinicians can accurately identify both the affected canal and laterality in peripheral vertigo, leading to appropriate treatment selection and improved patient outcomes.