Glucocorticosteroid Treatment in Acute Unilateral Vestibulopathy (Vestibular Neuronitis)

Inclusion Criteria: Medical History : * severe and prolonged rotatory vertigo; * acute onset, subacute, within 3 days; * nausea ; * imbalance. Physical examination : * spontaneous nystagmus beating towards the healthy ear (fast phase); * no evidence of central vestibular lesion; * Head impulse test abnormal, at least for the lateral semicircular canal (in some cases, the sign is only detectable for the 2 vertical semicircular canals with specific equipment, mostly not available in current practice); * areflexia or hyporeflexia (asymetry \> 70% calculated according to the classical Jongkees formula \[slow phase velocity of the nystagmus in response to caloric stimulation at (right at 30°C + right at 44°C) - ( left at 30°C + left at 44°C ) / (right 30°C + left 30°C + right 44°C + left at 44°C) x 100\], in the caloric test (10 cc in 20 s, at 30 and 44° C) Exclusion Criteria: * history of vestibular disorders other than benign paroxysmal positionning vertigo (BPPV); * symptoms lasting more than 3 days; * cochlear symptoms (deafness before, during or after vertigo); * central oculomotor dysfunction; * central vestibular dysfunction; * signs of brain dysfunction (e.g. epilepsy); * MRI (if done) abnormal central vestibular pathways; * psychiatric disease (history of psychiatric disease); * glaucoma ; * acute infection (herpes simplex, herpes zoster, corneal herpes, chicken pox, tuberculosis); * patients already on corticosteroids; * severe diabetes (fasting blood glucose \> 7 mmol/l); * Severe hypertension (systolic \>180; diastolic \> 110); * contraindications to glucocorticoids (peptic ulceration, osteoporosis confirmed by bone density tests or pathological fractures); * allergy to glucocorticoids or mannitol * malignant disease; * cardiac disease (recent myocardial infarction, heart failure); * liver dysfunction (cirrhosis) * renal insufficiency; * Pregnancy or breastfeeding.