Vertigo and nystagmus
Benign paroxysmal positional vertigo (BPPV) is a common cause of vertigo with episodes that typically last seconds to minutes when turning over in bed. It is caused by otoliths in the vestibular semi-circular canals (usually posterior canal). The Dix-Hallpike manoeuvre is a test for BPPV and should reveal a rotatory geotropic nystagmus. It is important, however, to also be aware of the other types of nystagmus that can be observed in patients and to differentiate between those with a more sinister central cause and those with a peripheral (vestibular) cause.
A helpful mnemonic for this is “HINTS”:
- (1) Head Impulse (no saccades observed in central-cause vertigo and the non-vertiginous patient)
- (2) Nystagmus (vertical and gaze-induced nystagmus are both linked to a central cause)
- (3) Test of Skew (in an alternate eye cover test the uncovered eye will demonstrate quick vertical gaze corrections if a central cause is present)