Quick Reference Card
Videonystagmography in one page
For clinic. Not a substitute for the full atlas.
Normal values
| Spontaneous nystagmus SPV | < 6°/s |
| VOR gain (vHIT) | ≥ 0.8 |
| Unilateral weakness | < 25% |
| Directional preponderance | < 30% |
| Fixation index (peripheral) | < 0.5 |
| Saccade peak velocity (20°) | > 300°/s |
| Saccade latency | ~200 ms |
| Smooth pursuit gain (< 0.4 Hz) | > 0.8 |
Jongkees formulas
Unilateral weakness (UW)
|(RW + RC) − (LW + LC)|
÷ (RW + RC + LW + LC) × 100
Threshold ≥ 25%. Tells you which ear is weak.÷ (RW + RC + LW + LC) × 100
Directional preponderance (DP)
|(RW + LC) − (RC + LW)|
÷ (RW + RC + LW + LC) × 100
Threshold ~30%. Asymmetry of direction, less specific.÷ (RW + RC + LW + LC) × 100
Caloric mnemonics
COWS
Cold Opposite, Warm Same
(refers to fast-phase direction)
(refers to fast-phase direction)
Body position
Supine, head elevated 30°
(horizontal canal vertical)
(horizontal canal vertical)
Frequencies tested
Caloric ≈ 0.003 Hz
Rotational chair ≈ 0.01–0.6 Hz
vHIT ≈ 5 Hz
Rotational chair ≈ 0.01–0.6 Hz
vHIT ≈ 5 Hz
HINTS exam — acute vestibular syndrome
| Component | Peripheral pattern | Central pattern (HINTS+) |
|---|---|---|
| Head Impulse | Positive (corrective saccade on affected side) | Normal (no saccade) |
| Nystagmus | Direction-fixed (Alexander's law) | Direction-changing with gaze |
| Test of Skew | Absent | Skew present |
One central feature is enough to require imaging. HINTS+ is more sensitive than early MRI for posterior circulation stroke. Requires acute, persistent vertigo and competent examination technique.
Slow-phase shape → localisation
| Slow phase shape | Suggests | Classic associations |
|---|---|---|
| Decreasing-velocity (decelerating) | Acute peripheral | Vestibular neuritis, labyrinthitis |
| Linear | Compensated peripheral or central | Check fixation suppression |
| Increasing-velocity (accelerating) | Ocular-motor / congenital | Infantile nystagmus syndrome (INS) |
| Envelope (crescendo-decrescendo) | BPPV canalithiasis | Posterior canal > horizontal canal |
| Sustained, no latency | BPPV cupulolithiasis | Treat with Semont liberatory |
| Pendular (sinusoidal) | Congenital or central | MS, brainstem stroke, oculopalatal myoclonus |
| Periodic reversal (~90–120 s) | Central — vestibulocerebellum | PAN. Often baclofen-responsive |
BPPV at a glance
| Feature | Canalithiasis | Cupulolithiasis |
|---|---|---|
| Latency | 1–5 s | None |
| Duration | < 60 s, crescendo-decrescendo | Sustained while in position |
| Fatigue | Yes, with repetition | No |
| Treatment | Epley (posterior) · BBQ roll (horizontal) | Semont liberatory |
Posterior canal ≈ 85–90% of BPPV. Horizontal canal ≈ 10%. Anterior canal < 2%.
Episodic vertigo — timing & clues
| Duration | Best fit | Key clue |
|---|---|---|
| < 1 min | BPPV | Triggered by position change |
| Minutes | Vestibular paroxysmia · TIA | Sudden, brief, recurrent |
| 20 min – 24 h | Ménière disease | Low-freq SNHL, fullness, tinnitus |
| 5 min – 72 h | Vestibular migraine | Photophobia/phonophobia, migraine hx |
| Days–weeks | Vestibular neuritis · stroke | Acute, persistent → HINTS |
Red flags — image first
- Pure vertical or pure torsional nystagmus in primary gaze
- Nystagmus that does not suppress with fixation (FI ≥ 0.7)
- Direction-changing nystagmus with gaze
- Skew deviation or vertical misalignment
- Normal head-impulse + acute persistent vertigo
- Down-beat nystagmus in primary gaze
- Up-beat nystagmus + altered mental status (suspect Wernicke)
- Acute vertigo + new neurological deficit
- Sudden onset in patient with vascular risk factors
- Pendular nystagmus in an adult (acquired)
Distilled from McCaslin (2013), Leigh & Zee (2006), Jongkees (1962), Bhattacharyya et al. (2017).
For educational use only. Not a clinical decision aid. Clinicians retain full responsibility for interpretation, diagnosis, and management.
For educational use only. Not a clinical decision aid. Clinicians retain full responsibility for interpretation, diagnosis, and management.