It is important to keep in mind that the majority of ENG tests are normal. Stockwell recently reported results from a series of 2,584 ENGs performed at a wide range of private and hospital-based laboratories. Normal results were obtained in 61 percent, and another 10 percent had only non-localizing findings. The majority of balance patients require advanced testing in addition to the core ENG battery. Since most ENG laboratories do not have rotation or CDP available, patients should be referred to a full-service balance center for these tests.
Rotation investigates the vestibular response across a wide range of frequencies and intensities.
Caloric unilateral weakness only. Rotation extends the search for evidence of lack of compensation. Can't do or trust calorics. Weak or absent caloric response. Caloric responses are too variable to be a reliable measure of bilateral hypofunction.