Resources
Glossary
The working vocabulary of bilateral vestibulopathy. Inline dotted terms throughout the chapter link here.
- Aminoglycoside ototoxicity
- Vestibular hair-cell damage from aminoglycoside antibiotics (notably gentamicin), one of the commonest identifiable causes of BVP; it is typically bilateral, may spare hearing, and can appear after apparently safe serum levels.
- Bilateral vestibulopathy (BVP) · bilateral vestibular hypofunction · bilateral vestibular loss
- A chronic syndrome of reduced or absent vestibular function on both sides, producing unsteadiness that worsens in the dark or on uneven ground, and oscillopsia (visual blurring) during head movement.
- Bithermal caloric test
- Irrigation of each ear with warm and cool water or air to drive the horizontal canal at low (~0.003 Hz) frequency. The Bárány criterion for BVP is a reduced caloric response with the sum of the maximum slow-phase velocities below 6°/s per ear.
- CANVAS
- Cerebellar Ataxia, Neuropathy and Vestibular Areflexia Syndrome — a slowly progressive degeneration (often RFC1-related) in which bilateral vestibulopathy coexists with cerebellar ataxia and a sensory neuropathy.
- Dandy's syndrome
- The historical eponym for the symptom complex of bilateral vestibular loss — oscillopsia and imbalance — described in patients after bilateral surgical vestibular nerve section.
- Dynamic visual acuity (DVA)
- The drop in measured visual acuity during head movement compared with the head still — a functional, bedside-to-laboratory marker of how much the failing VOR degrades vision.
- Gaze-stabilisation exercises
- Vestibular-rehabilitation exercises (e.g. ×1 and ×2 viewing) that drive adaptation and substitution to reduce oscillopsia and improve gaze stability when VOR function is reduced.
- Oscillopsia
- The illusion that the stationary visual world is jumping or bouncing during head movement — the hallmark symptom of a failing vestibulo-ocular reflex, classically while walking or in a moving vehicle.
- Romberg test
- Standing with feet together and eyes closed; marked worsening of sway when vision is removed is typical of bilateral vestibular (and proprioceptive) loss.
- Rotational chair test
- Sinusoidal whole-body rotation in darkness that quantifies VOR gain and phase across mid frequencies. Low gain with a short time constant / abnormal phase at 0.1 Hz is part of the Bárány criteria.
- Sensory substitution
- Rehabilitation strategy that trains greater use of vision and proprioception, plus saccadic and pursuit strategies, to compensate for absent vestibular input — central to managing severe BVP.
- Velocity storage
- A brainstem mechanism that prolongs and integrates vestibular signals, reflected in the rotational-chair time constant. It is shortened in bilateral peripheral loss.
- Vestibular areflexia
- Complete absence of a measurable vestibular response (e.g. no caloric response and absent vHIT VOR) — the severe end of the bilateral-vestibulopathy spectrum.
- Vestibular implant
- An investigational neuroprosthesis that delivers motion-modulated electrical stimulation to the vestibular nerve, aiming to restore a functionally useful VOR in severe bilateral loss.
- Vestibulo-ocular reflex (VOR)
- The reflex that rotates the eyes opposite to head movement to keep gaze stable on a target. Its bilateral failure is what produces oscillopsia and a positive head impulse test.
- Video head impulse test (vHIT)
- A goggle-based measurement of VOR gain and catch-up saccades during rapid, small head rotations — testing the canals at high (functional) frequency. Bilaterally reduced gain supports BVP.
- VOR gain
- The ratio of eye velocity to head velocity during a head impulse. A normal horizontal-canal gain is near 1.0; bilateral vestibulopathy is defined in part by a vHIT gain below 0.6 on both sides.