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Examination technique — Head Impulse, Nystagmus, Test of Skew

0:00Stand facing the patient at arm's length. Ask the patient to fixate on your nose and to relax their neck muscles. Place your hands on either side of the head, just above the ears.
0:22For the horizontal head impulse, tilt the head thirty degrees forward to bring the horizontal semicircular canals into the plane of testing. Apply a small, rapid, unpredictable head turn.
0:45Amplitude is approximately ten to twenty degrees, with a peak velocity of about 150 to 250 degrees per second.
1:00If the VOR is intact, the eyes stay locked on your nose throughout the head turn. If the VOR is impaired on the side of the head rotation, the eyes are dragged with the head and the patient generates a visible corrective saccade back to your nose at the end of the movement.
1:30The corrective saccade is the positive finding.
1:40For nystagmus, assess in primary gaze and in eccentric gaze — left, right, up, and down. Note the direction of the fast phase, whether it changes with gaze direction, and whether it has vertical or pure torsional components.
2:10Peripheral pattern: unidirectional, horizontal-torsional, fast phase beating away from the affected ear, suppressed by visual fixation.
2:30Central pattern: direction-changing on lateral gaze, vertical, pure torsional, or not suppressed by fixation.
2:48For the test of skew, have the patient fixate on your nose. Alternately cover one eye, then the other, releasing each cover for about a second before switching.
3:10Watch the uncovered eye as it takes up fixation. A vertical refixation movement, even a small one, is a positive skew — and a central red flag in acute vestibular syndrome.
3:35Finally, add HINTS-plus: assess for new unilateral hearing loss. New auditory loss in the setting of an otherwise peripheral HINTS pattern is the AICA-with-labyrinthine-artery stroke pitfall and warrants posterior fossa imaging.

Head Impulse

Head velocity Eye velocity Corrective saccade

VOR gain: 0.40 · abnormal — corrective saccade present (peripheral pattern)

VOR gain0.40

Peak head velocity200°/s

Drag the gain slider below 0.8 to produce the corrective saccade — the positive head-impulse finding. Bedside HINTS detects this saccade visually; vHIT measures it on a velocity trace like the one above.

Stand facing the patient at arm's length. Ask the patient to fixate on your nose and to relax their neck muscles. Place your hands on either side of the head, just above the ears. Tilt the head 30° forward to bring the horizontal semicircular canals into the plane of testing. Apply a small, rapid, unpredictable head turn of approximately 10–20° amplitude with a peak velocity of about 150–250°/s — small enough to avoid neck injury, fast enough to outpace smooth pursuit and visual fixation.

Watch the eyes during the impulse. If the VOR is intact, the eyes stay locked on your nose throughout the head turn. If the VOR is impaired on the side of the head rotation, the eyes are dragged with the head and the patient generates a visible corrective saccade back to your nose at the end of the movement. The corrective saccade is the positive finding².

Nystagmus

Switch patterns and toggle fixation to observe how peripheral nystagmus is suppressed by visual fixation, whereas central nystagmus is not. The direction-changing pattern reverses its fast phase as simulated gaze moves from left to right.

Assess spontaneous nystagmus in primary gaze and in eccentric gaze (left, right, up, down). Note the direction of the fast phase, whether it changes with gaze direction, and whether it has vertical or pure torsional components.

Peripheral pattern — unidirectional, horizontal-torsional, fast phase beats away from the affected ear, suppressed by visual fixation, enhanced by Frenzel lenses or removing fixation.
Central pattern — direction-changing on lateral gaze (fast phase reverses), vertical, pure torsional, or not suppressed by fixation.

Test of Skew

Vertical deviation: 2.0° · refixation amplitude 2.0° — positive skew (central red flag in AVS)

Vertical deviation2.0°

The cover alternates every 2 seconds. The covered eye drifts to its skew position; when the cover swaps, the newly uncovered eye makes a vertical refixation back to the target. Set deviation to zero to see no refixation — the normal finding.

Have the patient fixate on your nose. Alternately cover one eye, then the other, releasing each cover for about a second before switching. Watch the uncovered eye as it takes up fixation. A vertical refixation movement — even a small one — is a positive skew, and a central red flag in acute vestibular syndrome.

Trainee

Pitfalls and quality control

Predictable impulses. If you cue the patient with a slow ramp before each turn, smooth pursuit and visual fixation compensate; you will miss positive head impulses. Vary the timing and direction.
Insufficient velocity. Below ~100°/s the VOR is not fully challenged. Practise on healthy subjects to calibrate.
Covert saccades. Some corrective saccades happen during the impulse and can be missed at the bedside. Video head impulse testing (vHIT) captures these⁸.
Fixation suppression. Always observe nystagmus with and without fixation. Frenzel lenses, an ophthalmoscope to remove fixation in one eye, or video-Frenzel goggles are useful.

Clinician

HINTS-plus and audiometric testing

HINTS-plus adds new hearing loss as a central red flag — the rationale being that AICA territory infarction can involve the labyrinthine artery and present with peripheral-pattern HINTS but acute sensorineural hearing loss. In the setting of acute vestibular syndrome, new audiometric loss should prompt urgent posterior fossa imaging even when the three core HINTS findings look peripheral^10,1.