How do you determine if Benign Paroxysmal Positional Vertigo (BPPV) is bilateral or unilateral?

Determining if BPPV is Bilateral or Unilateral

To determine if Benign Paroxysmal Positional Vertigo (BPPV) is bilateral or unilateral, perform the Dix-Hallpike maneuver bilaterally and observe the pattern of nystagmus in each position, as a positive test on both sides with appropriate nystagmus indicates bilateral involvement.

Diagnostic Testing Approach

Dix-Hallpike Maneuver (Gold Standard for Posterior Canal BPPV)

• Position the patient seated upright on the examination table
• Turn the patient's head 45 degrees to the side being tested
• Quickly move the patient from sitting to supine position with the head extended approximately 20 degrees below horizontal
• Observe for characteristic nystagmus and vertigo symptoms
• Return the patient to sitting position
• Repeat on the opposite side

The test must be performed bilaterally to determine if one or both ears are affected 1.

Interpretation of Dix-Hallpike Results

• Unilateral BPPV: Positive test (characteristic nystagmus) on only one side
• Bilateral BPPV: Positive test with correspondingly appropriate nystagmus elicited for each ear in the dependent position 2
• A positive test for posterior canal BPPV shows torsional, upbeating nystagmus with a latency period and crescendo-decrescendo pattern lasting less than 60 seconds 1

Supine Roll Test (For Lateral Canal BPPV)

If Dix-Hallpike shows horizontal or no nystagmus, perform the supine roll test:

1. Position patient supine with head in neutral position
2. Quickly rotate the head 90° to one side
3. Observe for nystagmus
4. Return head to neutral position
5. Rotate head 90° to the opposite side
6. Observe for nystagmus 2

Distinguishing Bilateral from Unilateral BPPV

Key Indicators of True Bilateral BPPV

• Positive Dix-Hallpike test on both sides with appropriate directional nystagmus for each side
• Bilateral posterior canal BPPV is more likely to be encountered after head trauma 2, 3
• Accounts for approximately 10% of BPPV cases 3

Ruling Out False Bilateral Positivity

Some cases of apparent bilateral BPPV may actually be unilateral BPPV with misleading test results:

• Inappropriate head positioning during testing in unilateral BPPV can cause otolith debris in the uppermost ear to move toward the cupula, resulting in an inhibitory nystagmus that mimics bilateral BPPV 3
• In cases with torsional up-beating geotropic nystagmus on one side and down-beating nystagmus on the other side, have the patient sit up with head down at 30 degrees for half an hour before repeating the Dix-Hallpike maneuver. If the down-beating nystagmus disappears on repeat testing, this confirms unilateral posterior canal BPPV 4

Additional Diagnostic Methods

Bow and Lean Test

For lateral canal BPPV, this test can help determine the affected ear:

• Bowing position (face down): In geotropic form, nystagmus beats toward the affected ear; in apogeotropic form, nystagmus beats away from the affected ear
• Leaning position (face up): In geotropic form, nystagmus beats away from the affected ear; in apogeotropic form, nystagmus beats toward the affected ear 2

Lying-Down Nystagmus

When moving from sitting to straight supine facing up:

• In geotropic lateral canal BPPV: Nystagmus beats away from the affected ear
• In apogeotropic lateral canal BPPV: Nystagmus beats toward the affected ear 2

Clinical Pearls and Pitfalls

Important Considerations

• The Dix-Hallpike maneuver may need to be repeated at a separate visit to confirm the diagnosis and avoid false-negative results 2
• Factors affecting diagnostic accuracy include speed of head movements, time of day, and angle of the occipital plane during the maneuver 2
• Exercise caution when performing these maneuvers in patients with cervical stenosis, severe kyphoscoliosis, limited cervical range of motion, Down's syndrome, severe rheumatoid arthritis, cervical radiculopathies, Paget's disease, ankylosing spondylitis, low back dysfunction, spinal cord injuries, and morbid obesity 2, 1

Common Pitfalls

• Failure to perform the Dix-Hallpike maneuver bilaterally, which is essential for determining if BPPV is unilateral or bilateral
• Misinterpreting nystagmus patterns due to incorrect positioning or technique
• Not considering the possibility of multi-canal involvement or mixed BPPV types
• Overlooking the higher prevalence of right-sided BPPV (right labyrinth is affected 1.41 times more often than the left) 5

By systematically performing and interpreting these diagnostic maneuvers, clinicians can accurately determine whether BPPV is unilateral or bilateral, which is crucial for appropriate treatment planning.