Rotatory Chair Testing

Rotatory chair testing is a key diagnostic tool used to evaluate the vestibular system—the part of the inner ear and brain that helps control balance and eye movements. This test is often performed in patients with dizziness, vertigo, or unexplained balance disorders. The procedure involves securely seating the patient in a motorized chair that rotates gently at controlled speeds while sensors monitor eye movements (electronystagmography or videonystagmography).

How Rotatory Chair Testing Works

The chair rotates in a darkened room, and the patient’s eyes are tracked to measure the vestibulo-ocular reflex (VOR). The VOR is responsible for stabilizing vision during head movements. By analyzing how the eyes respond to different speeds and directions of rotation, clinicians can pinpoint abnormalities in the inner ear or central nervous system. Common parameters measured include gain (the ratio of eye movement to head movement), phase (timing of the response), and symmetry (equal response from both ears).

Key Phases of the Test

Pre-rotatory baseline: The patient is positioned and calibrated to ensure accurate eye tracking.
Constant velocity rotation: The chair rotates at a steady speed (e.g., 60°/s) to assess the VOR response.
Sinusoidal harmonic acceleration (SHA): The chair oscillates back and forth at varying frequencies (0.01–0.64 Hz) to test the system’s adaptability.
Step velocity test: The chair suddenly accelerates or decelerates to evaluate the response to rapid changes.
Post-rotatory nystagmus: After stopping, the persistent eye movements (nystagmus) are measured to assess recovery.

Clinical Applications and Benefits

Rotatory chair testing is highly valuable for diagnosing conditions such as bilateral vestibular loss, Meniere’s disease, superior semicircular canal dehiscence, and central vestibular disorders. It is also used to monitor recovery after vestibular neuritis or traumatic brain injury. The test is non-invasive, well-tolerated, and provides objective data that complements other methods like caloric testing and video head impulse test (vHIT).

What to Expect During the Test

You will be asked to wear goggles or electrodes to record eye movements. The room will be dark or dimly lit to reduce visual fixation. You will remain seated and alert, often counting backward or performing mental tasks to keep the eyes from suppressing the reflex. The entire session typically lasts 20–45 minutes. There may be mild dizziness during rotation, but serious discomfort is rare.

Interpreting Results

Normal results show well-synchronized eye movements relative to chair rotation, with appropriate gain and minimal asymmetry. Abnormal findings can indicate:

Low gain: suggests peripheral or central vestibular impairment
Large phase lead: often seen in compensated or chronic lesions
Asymmetry: points to a unilateral weakness
Prolonged nystagmus: may indicate a central lesion

These results help guide treatment, including vestibular rehabilitation, medication, or surgical interventions.

Conclusion