Reference
Glossary
Searchable terminology with aliases and cross-references.
- Subjective Visual Vertical (SVV)(SVV, visual vertical)
- The angle a person perceives as upright when adjusting a luminous line in an otherwise dark environment. Reflects central integration of otolith (graviceptive) input, ocular counter-roll, and visual cues. Normal range in healthy adults is roughly ±2° from true earth-vertical.
- Subjective Visual Horizontal (SVH)(SVH)
- Same paradigm as SVV but with the perceived horizontal axis. Test–retest reliability and disease sensitivity are comparable to SVV; the two are typically orthogonal and used interchangeably in most labs.
- Utricle
- Horizontally-oriented otolith organ that senses linear acceleration in the earth-horizontal plane and head tilt in the roll plane. The dominant graviceptor in upright stance; SVV tilt after unilateral vestibular loss is largely a utricular signal.
- Saccule
- Vertically-oriented otolith organ sensing vertical linear acceleration (e.g., gravity along the long axis of the body). Primary afferent target for cVEMP. Contributes less to SVV than the utricle.
- Ocular Tilt Reaction (OTR)(OTR)
- Triad of head tilt, skew deviation, and ocular counter-roll, all toward the same side. Indicates a lesion of the graviceptive pathway from the utricle to the interstitial nucleus of Cajal. SVV tilts toward the lower (hypotropic) eye in peripheral and pontomedullary lesions; tilts to the contralesional side in pontomesencephalic lesions above the decussation.
- Skew deviation
- Vertical misalignment of the eyes arising from imbalance of otolith input. One eye is hypertropic, the other hypotropic. Part of the ocular tilt reaction.
- Interstitial nucleus of Cajal (INC)(INC)
- Midbrain integrator for vertical and torsional eye position, located in the rostral midbrain near the rostral interstitial nucleus of the medial longitudinal fasciculus. Lesions cause contraversive OTR and SVV tilt.
- Graviception
- The neural sense of gravity. Combines otolith afferents, somatosensory cues (truncal graviceptors), and visual cues; integrated in the brainstem, cerebellum, thalamus, and parieto-insular vestibular cortex.
- Bucket test
- Low-cost SVV paradigm: the patient looks into a bucket with a vertical line drawn inside the rim, eliminating external visual cues. The examiner rotates the bucket from a tilted starting position until the patient calls the line vertical. Validated against laboratory SVV with ~1° agreement.
- Vestibular Evoked Myogenic Potential (VEMP)(VEMP, cVEMP, oVEMP)
- Short-latency myogenic reflex to high-intensity sound or vibration; cVEMP probes saccule→inferior vestibular nerve→SCM, oVEMP probes utricle→superior vestibular nerve→inferior oblique. Companion test to SVV for otolith function.
- Wallenberg syndrome(lateral medullary syndrome)
- Lateral medullary stroke producing ipsiversive OTR and ipsilesional SVV tilt (often large, 5–15°). Classic localiser for vestibular nuclei involvement.
See also: Subjective Visual Horizontal (SVH), Ocular Tilt Reaction (OTR), Utricle
See also: Subjective Visual Vertical (SVV)
See also: Saccule, Ocular Tilt Reaction (OTR), Subjective Visual Vertical (SVV)
See also: Utricle, Vestibular Evoked Myogenic Potential (VEMP)
See also: Subjective Visual Vertical (SVV), Interstitial nucleus of Cajal (INC), Skew deviation
See also: Ocular Tilt Reaction (OTR)
See also: Ocular Tilt Reaction (OTR)
See also: Subjective Visual Vertical (SVV), Utricle
See also: Subjective Visual Vertical (SVV)
See also: Ocular Tilt Reaction (OTR), Subjective Visual Vertical (SVV)