Caloric testing involves irrigation with which substances to test the vestibular system?

• A. Rotational testing
• B. Caloric testing
• C. Oculocephalic testing
• D. Vestibular evoked myogenic potentials

Answer: (B)

Caloric testing uses temperature-driven stimulation of the horizontal semicircular canal by irrigating the ear canal with warm and cold substances. Introducing warm water (or warm air) and cold water (or cold air) creates convection currents in the endolymph, activating the vestibular nerve on the treated side and producing a measurable vestibulo-ocular response. The resulting nystagmus follows the COWS rule: warm irrigation evokes quick eye movements toward the irrigated ear, while cold irrigation evokes quick movements away from the irrigated ear. This method specifically assesses horizontal canal function and unilateral vestibular integrity. Other tests rely on different stimuli—rotational testing uses head/body movement, oculocephalic testing checks brainstem pathways, and vestibular evoked myogenic potentials use loud sounds to probe additional vestibular connections.