<prompt> Glycerol test is done inOtosclerosisLateral sinus thrombosisMenieres diseaseNone of the above  <response>: Glycerol is a dehydrating agent. When given orally, it reduces endolymph pressure and thus causes an improvement in hearing. It is diagnostic of Menieres disease. The patient is given glycerol1.5mlkg with an equal amount of water and a little flavouring agent or lemon juice. Audiogram and speech discrimination scores are recorded before and 1-2 hr after ingestion of glycerol. An improvement of 10db in two or more adjacent octaves or gain of 10 co in discrimination score makes the test positive. There is also improvement in tinnitus and in the sense of fullness in the ear. The test has a diagnostic and prognostic value. These days, the glycerol test is combined with electrocochleography. Ref: Diseases of EAR, NOSE and THROAT by PL Dhingra 7th Edition page no.113 