Rotation tests

Besides ENG (electronystagmography), rotation tests are another way of evaluating how well the eyes and inner ear work together. The inner ear sends signals about head movement to the brain, causing signals to be sent to the muscles of the eyes via the vestibulo-ocular reflex (VOR). For every head movement in one direction, there is eye movement in the opposite direction.

With rotation tests (which employ the same type of sticky-patch electrodes or goggles used for ENG), the examiner can record eye movements while the head is moving at various speeds. This provides additional information, beyond the ENG, about how well the balance organs are functioning, along with their connections to the eye muscles. Not all people in the diagnosis phase will need rotation tests.

There are two kinds of computerized rotation tests: auto head rotation and rotary chair. In auto head rotation tests, the person being tested is asked to look at a fixed target and move his/her head back and forth or up and down for short periods of time. During rotary-chair tests, the computerized chair moves for the person being tested. For safety, a harness is worn and the head is restrained against a headrest.

Rotary-chair testing usually takes place in a darkened room. A microphone and speaker in the testing room allow voice contact with the examiner, who is seated at a computer console just outside the door. As in ENG testing, while the eye movements are recorded, the person being tested will be asked a series of simple questions that are meant to keep the mind busy and alert during the tests.

Not all rotation testing is computerized. In some cases a swivel chair is used, or the doctor or other examiner simply moves the person's head with his or her hands while observing the eye movements.