What it measures:
Gold standard to confirm the diagnosis of BPPV and identify the semicircular canal (SCC) involvement, particularly posterior SCC involvement.
People with benign paroxysmal positional vertigo (BPPV)
Use in Patient Classification
BPPV is classified according to:
- The SCC involved (posterior, anterior, horizontal)
- Location of the displaced otoconia-inside the canal (canalithiasis), or adhering to the cupula (cupuloithiasis)
These classifications guide intervention.
The involved SCC is determined based on the observation that nystagmus occurs when the patient is in the provoking position. The nystagmus elicited in BPPV takes the form of a jerk nystagmus-a slow drift toward one direction and then a fast corrective saccade back the other way. The nystagmus is named for the direction of the fast component. All eye movement directions are named with respect to the patient, not the observer.
The Dix-Hallpike Test can elicit vertigo and nystagmus associated with BPPV involving any of the SCCs but most often the posterior or anterior SCC. For posterior and anterior SCC involvement, the nystagmus is named for the direction of the fast phase of the eye in the orbit (upbeating, downbeating, rightward and leftward torsional).
Both the Dix-Hallpike Test and the side-lying test can be used to identify anterior SCC BPPV. In both tests, the contralateral anterior SCC is in the plane of the pull of gravity. The anterior SCC of the ipsilateral (downside) ear also is in a dependent position, and, if the head is sufficiently below the horizontal, the maneuver may trigger vertigo due to anterior SCC involvement of the ipsilateral ear. With both tests, therefore, identification of the involved side in anterior SCC has to be based on the direction of the torsional component of the nystagmus.
Several other tests have been described as being useful for identifying anterior SCC BPPV. The evidence is limited, however, to descriptions of case series, and none of the studies report sensitivity or specificity. Only one test is mentioned in several articles.4-7 Observation of downbeating and torsional nystagmus is performed when the patient lays straight back and the head is hanging between 30 and 60 degrees. The 4 articles reported on only a total of 22 cases.
Anterior SCC BPPV: Both tests can be used to identify anterior SCC BPPV. With both tests, identification of the involved side in anterior SCC has to be based on the direction of the torsional component of the nystagmus. There are other tests that might be useful, but evidence to support them is limited to case series, with no reports of sensitivity or specificity.
Posterior and anterior SCC BPPV: In anterior and posterior SCC BPPV, vertigo and nystagmus occur when the head is in the provoking position and reverse when the patient returns to sitting. In both tests, for posterior SCC BPPV, the affected side is the typically the "down-side" ear. More important, for both posterior and anterior SCC BPPV, the direction of the torsional component of the nystagmus will always be toward the affected ear in the initial provoking position.
In canalithiasis, the initial nystagmus will subside, and there may be a secondary nystagmus that is in the opposite direction of the initial nystagmus (reversal period). The clinician needs to be careful not to determine canal involvement on the appearance of nystagmus during the reversal period when the patient is in the provoking position.
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