The purpose of this study is to evaluate the safety of OTO-104 in subjects with unilateral Meniere's disease. The effectiveness of OTO-104 to reduce the symptoms of Meniere's disease will also be evaluated.

Meniere's disease is a debilitating disorder of the inner ear which includes symptoms such as vertigo, tinnitus, hearing loss and aural fullness. Meniere's disease may result from an imbalance of fluid in the inner ear. Several studies have shown that corticosteroids may help manage this imbalance yet the effect does not last very long. OTO-104 is a longer lasting corticosteroid which could provide significant benefit to patients with Meniere's disease.

Inclusion Criteria:

1. Subject has a diagnosis of unilateral Meniere's disease by 1995 American Academy of Otolaryngology - Head and Neck Surgery (AAOHNS) criteria and reports active vertigo for the 2 months prior to the study lead-in period.
2. Subject has experienced active vertigo during the lead-in period.
3. Subject has asymmetric low frequency sensorineural hearing loss.
4. Subject agrees to maintain their current treatments for Meniere's disease while on-study.
5. Subjects not currently on a low-salt diet or diuretic should have a medical history of having used one or both of these treatments for at least 1 month without relief of symptoms.
6. Subjects currently on a low-salt diet and/or diuretic at the time of screening agree to continue this treatment throughout the study.

Exclusion Criteria:

1. Subject has an infection in the ear, sinuses, or upper respiratory system.
2. Subject is pregnant or lactating.
3. Subject has a history of immunodeficiency disease.
4. Subject has a history of previous endolymphatic sac surgery.
5. Subject has a history of previous use of intratympanic (IT) gentamicin in the affected ear.
6. Subject has a history of tympanostomy tubes with evidence of perforation or lack of closure.
7. Subject has experienced an adverse reaction to IT injection of steroids.
8. Subject has used an investigational drug or device in the 3 months prior to screening.
9. Subject has had a duration of Meniere's disease of >20 years.