Execution
- 1Position the patient sitting with fixation removed when possible using Frenzel lenses or video goggles.
- 2Flex the head forward about 30° to bring the horizontal canals closer to the test plane.
- 3Oscillate the head horizontally for about 20 cycles or approximately 15 to 20 seconds.
- 4Stop the movement abruptly and ask the patient to keep the eyes open.
- 5Observe for direction, duration, and suppression of post-head-shaking nystagmus.
Positive outcome
A clear post-head-shaking nystagmus is positive and suggests dynamic vestibular asymmetry. Unidirectional horizontal nystagmus often supports peripheral vestibular imbalance, while vertical, direction-changing, or poorly suppressible nystagmus raises central concern. Absence of nystagmus does not rule out vestibular disease.
Studies
| Study | Reliability | Sn | Sp | LR+ | LR− |
|---|---|---|---|---|---|
| Jacobson et al. (1990) | diagnostic study | 46 | 75 | 1.84 | 0.72 |
| Vazquez et al. (2005) | caloric comparison study | 48.8 | 95 | 9.76 | 0.54 |
CommentHead-shaking nystagmus is useful as a vestibular asymmetry screen but has variable sensitivity. Fixation suppression can hide findings, so the test is stronger with fixation removed. Direction and context matter more than simply labeling it positive.
Moderate Clinical Value