<prompt> The following test is useful for diagnosis ofUnsafe CSOMMenieres diseaseGradenigo syndromeCholesteatoma  <response>: Ans. b Menieres disease. The image shows performance of the caloric stimulation test. Irrigation of the external meatus with water 7deg above and later 7deg below body temperature sets up convection currents of the endolymph in the semi-circular canals. This causes nystagmus, and the duration of the nystagmus gives an index of the activity of the labyrinth. The nystagmus can be directly observed or recorded electrically electronystagmography. This test is particularly valuable in the diagnosis of Menieres disease and acoustic neuroma. A reduced or absent nystagmus is found canal paresis. 