At NDBC clinics, we utilize the very sophisticated Neurokinetics rotational chair used by medical research faculties across the world like the Mayo Clinics, John Hopkins University Medical System, and other premier medical systems.

The purpose of rotational chair testing is to determine if the vestibular (inner ear) or the neurological system is the cause of a balance disorder. When someone is turning their head, the vestibular system sends continuous signals to the brain updating it on the heads position. This causes additional signals to be sent to the muscles of the eyes via the vestibular ocular reflex (VOR). For every head movement in one direction, there is eye movement in the opposite direction. This phenomena is the basis for the rotational chair testing.

Rotational chair testing can be very helpful in detecting bilateral loss (no function in both ears) of vestibular function or if there are cerebellar ocular motor abnormalities. In recent studies, many people with neurological problems or vestibular ocular reflex (VOR) have been diagnosed with the use of the rotary chair very successfully.

Rotational chair testing is usually ordered in addition to ENG/VNG (caloric) testing to confirm a specific diagnosis and increase accuracy. This allows a physician to see precisely what head movement speeds are effected by the inner ear disturbance if a one is noted during the ENG/VNG testing exam. This cannot be achieved with any other testing procedure, and ensures the physician and accurate diagnosis specific to the problem within the vestibular system.

For More Information About Rotational Chair Testing, Watch the Video Below:

Rotational Chair Testing

The Rotational Chair Testing Procedure

Rotational chair testing is conducted in a round enclosed room with a chair in the middle that rotates back and forth in an arc. This motion is precisely controlled by a computer, which records your eye movements during the test using infrared video goggles. These tests both determine if the the semi-circular canals of the inner ear are functioning properly, where 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.

NeuroKinetics Rotational Chair