Resources
Glossary
The working vocabulary of positional vertigo and its treatment. Inline dotted terms throughout the chapter link here; click any chapter marker to jump to its definition.
- Acute vestibular syndrome (AVS)
- Rapid-onset, continuous vertigo with nausea, nystagmus and gait instability lasting days. Unlike BPPV it is not positional and triggered; central causes (stroke) must be excluded.
- Apogeotropic nystagmus
- Horizontal nystagmus that beats away from the ground (toward the uppermost ear) on the supine roll test. In horizontal-canal BPPV it indicates cupulolithiasis or anterior-arm debris; the less intense 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 most common cause of peripheral vertigo.
- Canal conversion (canal switch)
- Iatrogenic migration of otoconia from one semicircular canal into another during a repositioning manoeuvre — most often posterior-to-horizontal — producing a new pattern of positional nystagmus.
- Canalith repositioning procedure (CRP) · repositioning manoeuvre · particle repositioning
- A sequence of head and trunk positions that uses gravity to roll dislodged otoconia out of a semicircular canal back into the utricle, where they no longer provoke vertigo.
- Canalithiasis
- Otoconia floating freely within the lumen of a semicircular canal. Movement of the debris under gravity deflects the cupula a moment after the head moves — giving the characteristic latency and brief, fatiguing nystagmus.
- Common crus
- The shared bony channel where the posterior and superior (anterior) semicircular canals join before entering the vestibule. Repositioning manoeuvres aim to carry debris through it back into the utricle.
- Cupulolithiasis
- Otoconia adherent to the cupula itself, making it persistently gravity-sensitive. Produces a longer-lasting, less fatiguing nystagmus and underlies the apogeotropic form of horizontal-canal BPPV.
- Dix–Hallpike test
- The gold-standard positional test for posterior-canal BPPV: from sitting, the head is turned 45° and the patient laid back into head-hanging, provoking a torsional-upbeat nystagmus when positive.
- Geotropic nystagmus
- Horizontal nystagmus that beats toward the ground (the lowermost ear) on the supine roll test. In horizontal-canal BPPV it indicates canalithiasis; the more intense side localises the affected ear.
- HINTS examination · Head Impulse–Nystagmus–Test of Skew
- A three-step bedside oculomotor battery used in acute vestibular syndrome to separate peripheral from central causes; a 'central' pattern is more sensitive than early MRI for posterior-circulation stroke.
- Otoconia (otoliths) · canaliths · otoconial debris
- Calcium-carbonate crystals normally embedded in the otolithic membrane of the utricle and saccule. When dislodged into a semicircular canal they make it gravity-sensitive, producing positional vertigo.
- Supine roll test (Pagnini–McClure)
- Diagnostic test for horizontal-canal BPPV: with the patient supine, the head is rolled 90° to each side to elicit horizontal nystagmus and classify it as geotropic or apogeotropic.
- Utricle
- The otolith organ that senses horizontal linear acceleration and is the origin and intended destination of canalith debris during repositioning.