Summary

What it measures:

Used to confirm diagnosis of benign paroxysmal positional vertigo (BPPV) and identify the involved semicircular canal (SCC), most commonly the horizontal SCC.

Target Population:

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.

Horizontal SCC: In patients with horizontal SCC BPPV, the Hallpike-Dix Test and side-lying test might not provoke vertigo and nystagmus because the horizontal SCC is not placed in the plane of the pull of gravity. In the roll test, the patient is supine and the head is rolled 90 degrees to the right and left in the plane of the horizontal SCC.^3-5

The direction of the nystagmus elicited (geotropic versus apogeotropic)-as well as duration of nystagmus-are used to identify the canalithiasis versus cupulolithiasis form of horizontal SCC BPPV.

Guidance:
The determination of whether a person has the canalithiasis or the cupulolithiasis form of horizontal SCC BPPV is based on the direction of nystagmus; however, clinicians need to aware that horizontal SCC canalithiasis typically presents as geotropic nystagmus that is brief, and cupulolithiasis as apogeotropic nystagmus that is prolonged. Nystagmus that is geotropic and prolonged is not typical of BPPV and more likely is from a migraine equivalent event. It is recommended, therefore, that clinicians note both the direction of the nystagmus and the duration of the nystagmus as criteria for distinguishing between horizontal SCC canalithiasis and cupulolithiasis.

Using the roll test, in canalithiasis, the affected side is believed to be the side that is most symptomatic.⁶ In cupulolithiasis, nystagmus and patient reports of vertigo are believed to be worse toward the unaffected ear during the roll test.⁷ Side of involvement can be clarified using the Bow and Lean test.