Discovery of the Caloric Reflex Test

The caloric reflex test checks the vestibulo-ocular reflex by irrigating cold or warm water or air into the external auditory canal. The method was developed by the Austrian-born otologist Robert Bárány, who received the 1914 Nobel Prize in Physiology or Medicine for this work. Bárány noticed in his Vienna practice that a patient whose ear was syringed with fluid that was too cold developed vertigo and nystagmus, and that when he warmed the fluid the nystagmus ran in the opposite direction. He reasoned that the endolymph sinks when it is cool and rises when it is warm, so the direction of its flow gives the proprioceptive signal to the vestibular organ. Physicians and audiologists still use calorics to confirm asymmetric function in the peripheral vestibular system, and the test is one of several used when brain stem death is being assessed. The research that came from the observation made surgical treatment of vestibular organ diseases possible.