Vestibular Autorotation Test & Rotary Chair Testing Rotary Testing Vestibular Autorotation Test & Rotary Chair Testing

Passive and Active Rotation Passive– pt is moved (head or whole body) by examiner. Halmagyi Head Thrust Rotary Chair tests Active—pt is asked to turn their own head. Head Shake VAT

Passive Tests Sinusoidal Acceleration Test: Velocity Step Tests: Oscillating (left-right) in rotary chair Freqs from 0.01 to 0.64 Hz Peak angular velocities 50° per sec Velocity Step Tests: Sudden Accelerations (to left or right) Of 100° per sec for 1 second Responses recorded for following minute, or so.

Vestibular Autorotation Test (VAT) “no” & “yes” gestures in time with metronome Frequencies from 0.5 to 6 Hz over 18 seconds While pt. fixates visually Head motion recorded by accelerometer Eye motion recorded via video or electrodes

Head Shaking Test Pt shakes head for 20 seconds With Frenzel lenses in dark room Look for post-shaking nystagmus

Measures from Rotational Tests Gain: Ratio of eye velocity to head velocity Phase: (in SAT/VAT) lag between head and eye movements (away from 180°) Symmetry: Ratio of rightward to leftward eye velocity. Time Constant: (in Vel. Step) time taken for eye velocity to decline to 37% of peak value.

VAT Gain and Phase Measures

Dynamic Visual Acuity Test Visual Acuity—discrimination of shapes of different sizes during active head movement. Packaged systems / Snellen Chart