Resources
Glossary
The working vocabulary of positional vertigo. Inline dotted terms throughout the chapter link here.
- Apogeotropic nystagmus
- Horizontal nystagmus beating away from the ground; indicates cupulolithiasis or anterior-arm debris, and the weaker side localises the affected ear.
- Benign paroxysmal positional vertigo (BPPV)
- Brief, recurrent episodes of vertigo provoked by changes in head position relative to gravity, caused by displaced otoconia within a semicircular canal. The commonest cause of peripheral vertigo.
- Canalithiasis
- Free-floating otoconia within a semicircular canal. Movement under gravity deflects the cupula a moment after the head moves — giving the characteristic latency and brief, fatiguing nystagmus.
- Central positional vertigo / nystagmus
- Positional vertigo arising from cerebellar or brainstem pathology. Suggested by non-fatiguing nystagmus, absent latency, pure downbeat or direction-changing patterns, and accompanying neurological signs.
- Cupulolithiasis
- Otoconia adherent to the cupula, making it persistently gravity-sensitive. Produces a longer-lasting, non-fatiguing nystagmus that is more resistant to standard repositioning.
- Dix–Hallpike test
- The gold-standard provocation test for posterior-canal BPPV: from sitting with the head turned 45°, the patient is laid into head-hanging, eliciting torsional-upbeat nystagmus when positive.
- Fatigability
- Diminution of the vertigo and nystagmus on repeated positional testing, as otoconia disperse or responses habituate. Characteristic of peripheral BPPV and absent in central positional nystagmus.
- Geotropic nystagmus
- Horizontal nystagmus beating toward the ground on the supine roll test; in horizontal-canal BPPV it indicates canalithiasis, and the stronger side localises the affected ear.
- Latency
- The 1–5 second delay between reaching the provocative position and the onset of vertigo and nystagmus — the time free otoconia take to move. A hallmark of canalithiasis; central lesions lack it.
- Otoconia (otoliths) · canaliths
- Calcium-carbonate crystals normally embedded in the otolithic membrane of the utricle. When dislodged into a semicircular canal they make it gravity-sensitive and cause positional vertigo.
- Secondary BPPV
- BPPV following an identifiable cause — head trauma, vestibular neuritis, ear surgery or Ménière's disease — more often multi-canal, bilateral, or resistant to repositioning than idiopathic BPPV.
- Supine roll test (Pagnini–McClure)
- Test for horizontal-canal BPPV: supine with the head flexed ~30°, the head is rolled 90° to each side to elicit horizontal nystagmus and classify it as geotropic or apogeotropic.