Rotational chair testing was first introduced by Bárány in 1907. He initially designed the chair for VOR testing with impulsive rotation in mind. His first test consisted of manual rotating the chair 10 times over 20 seconds followed by a sudden stop of the chair to analyze the postrotary nystagmus of the patient.

Rotational chair testing has undergone numerous changes since that time and now has additional applications, including testing of visual-vestibular interaction, optokinetic after-nystagmus (OKAN), high-velocity sinusoidal testing, and off-vertical axis rotation (OVAR).

The purpose of rotational chair testing is to determine whether or not dizziness may be due to a disorder of inner ear or brain. This tests measures the dizziness (nystagmus) while slowly being turned in a chair that rotates back and forth. Rotational chair testing is usually ordered in addition to ENG/VNG (caloric) testing to confirm a diagnosis and increase accuracy.

These tests both determine if the the semi-circular canals of the inner ear are functioning properly, but ENG/VNG tests by themselves may be falsely positive or falsely negative if not administered properly. ENG/VNG are usually falsely positive because ear wax can sometimes block one of the ear canals. Rotary chair testing is not affected by mechanical obstructions of the ear like ear wax. ENG/VNG can be falsely negative particularly in situations where there is damage to each ear that has not been accounted for.

The Three Parts of Rotational Chair Testing:
1. The Rotational Chair Testing Procedure
2. The Optokinetic Test
3. The Fixation Test

1. Rotational Chair Testing Procedure
The rotational chair testing procedure objectively measures the semicircular canals at a higher (and more physiologic) frequency than with caloric testing. The test is an integration of responses from both the right and left vestibular systems, unlike caloric testing which tests them independantly. This test measures dizziness by recording the eye movements (nystagmus) while the chair is being rotated. The computer controls the movement of the testing cylinder and compares the nystagmus movements with the movement of the testing cylinder looking for any discrepancies. As a general rule, patients with inner ear diseases become less dizzy than do normal persons because of their vestibular deficient.

The patient is rotated in a chair at a velocity of from .01 to 1.28 Hz. The slow component of the physiologically induced nystagmus is analyzed in terms of phase, gain, and symmetry of eye movement. Symmetry between vestibular systems is measured by comparing the peak slow-wave velocities between left and right rotations of the patient. In acute vestibular lesions, the symmetry measure shows weakness on the affected side, though confounding factors such as compensation, labyrinthine irritation, and cerebellar lesions may render the symmetry test unreliable. Rotatory chair testing is generally more palatable to patients than caloric testing (especially pediatric patients). It is useful in monitoring changes in vestibular function over time, in monitoring compensation after acute injury, and in monitoring residual labyrinthine function in patients with no response during caloric testing.

2. The Optokinetic Testing Procedure
The optokinetic testing procedure measures the dizziness caused by the subject looking at different strips of lights that appear on the wall of the testing cylinder. The eyes will follow a stripe and then make a quick (movement) saccade to catch up with the next stripe, resulting in the pattern of optokinetic nystagmus. Lesions responsible for abnormalities in the slow phase of the nystagmus are similar to those responsible for smooth pursuit system defects. This test is also performed using ENG/VNG equipment, but performing this test in the testing cylinder enables for a true 360 degree visual field for more complete data. Optokinetic testing is sometimes useful in diagnosis of bilateral vestibular loss and central conditions.

3. The Fixation Testing Procedure
The fixation test measures nystagmus while a person is being rotated in the cylinder while looking at a dot of light that is rotating with them. This would be similar to concentrating on your finger while holding it in front of your eyes, and spinning yourself in circles. This confuses the vestibular system and nystagmus can be measured. The ability to suppress fixation on the dot is impaired by central nervous system conditions and improved by bilateral vestibular loss.