How do we determine which ear is affected in benign paroxysmal positional vertigo?

Determining the Affected Ear in BPPV

The affected ear in BPPV is determined by the side that produces characteristic nystagmus during specific positional testing: for posterior canal BPPV, the affected ear is the one facing downward during a positive Dix-Hallpike maneuver; for lateral canal BPPV, the affected ear is the side producing the most intense nystagmus in geotropic variants or the opposite side in apogeotropic variants. 1, 2

Posterior Canal BPPV (85-95% of cases)

Perform the Dix-Hallpike maneuver bilaterally to identify the affected side 1:

• Turn the patient's head 45° toward the suspected side while seated, then rapidly lower them supine with head extended 20° below horizontal 1
• The affected ear is whichever side is down when you elicit the characteristic response 2
• A positive test shows torsional upbeating nystagmus with 5-20 second latency, crescendo-decrescendo pattern, and resolution within 60 seconds 1, 2

Critical pitfall: If you only test one side and it's negative, you must test the opposite side—the affected ear is simply the one that triggers the response 1

Lateral Canal BPPV (10-15% of cases)

Perform the supine roll test when Dix-Hallpike is negative but BPPV is suspected 1, 3:

• Position patient supine with head neutral, then rapidly rotate head 90° to one side, observe for horizontal nystagmus, return to neutral, then rotate 90° to opposite side 4, 3

Geotropic Type (Most Common)

• The side producing the most intense horizontal nystagmus beating toward the ground is the affected ear 4, 1, 3
• Both sides will show geotropic nystagmus (beating toward the undermost ear), but the affected side produces stronger nystagmus 4, 3

Apogeotropic Type (Less Common)

• Horizontal nystagmus beats toward the uppermost ear on both sides 4
• The affected ear is the side opposite to where the strongest nystagmus occurs 1
• This variant occurs when debris is adherent to or near the ampulla rather than free-floating in the canal 1

Practical Algorithm

1. Start with bilateral Dix-Hallpike testing for posterior canal involvement 1
2. If negative but clinical suspicion remains high, proceed immediately to supine roll test for lateral canal BPPV 1, 3
3. Compare nystagmus intensity between sides—the stronger response localizes the affected ear in most cases 4, 1
4. If initial treatment fails after 2-4 attempts, repeat complete positional testing as canal conversion occurs in up to 6% of cases 1

Common Diagnostic Pitfalls

• Never skip the supine roll test—lateral canal BPPV accounts for 10-15% of cases and is frequently missed when clinicians only perform Dix-Hallpike 1, 3
• CNS adaptation may cause spontaneous nystagmus direction changes without repositioning, which can confuse lateralization 4, 1
• Approximately 20% of lateral canal cases remain unclear for lateralization despite proper testing 1
• Multiple canal involvement occurs in 4.6-6.8% of cases, most commonly ipsilateral posterior and lateral canals, which may only become evident after treating the first canal 1

Safety Precautions

Exercise caution in patients with cervical stenosis, severe kyphoscoliosis, limited cervical range of motion, Down syndrome, severe rheumatoid arthritis, cervical radiculopathies, Paget's disease, ankylosing spondylitis, low back dysfunction, spinal cord injuries, or morbid obesity 4, 2, 3