ENG/VNG is the most commonly used test to evaluate the vestibular system (balance portions of the inner ear, nerve, and brain). When the head is in motion, the inner-ear balance (vestibular) organs send signals to the eye muscles to keep vision in focus. Therefore, eye movements can be used to evaluate the balance system. Patients are asked to follow a moving light with their eyes and sit and lie in different positions while their eye movements are monitored with infrared goggles. Each ear canal is also irrigated with small amounts of warm and cool water (caloric test) as the patient lies on an examination table. The water causes a temperature change that creates eye movements (nystagmus) that can be measured and compared for each ear. VNG takes approximately 1 – 2 hours.