The cause of Ménière's disease is unclear but likely involves both genetic and environmental factors. A number of theories exist for why it occurs including constrictions in blood vessels, viral infections, and autoimmune reactions. About 10% of cases run in families. Symptoms are believed to occur as the result of increased fluid build up in the labyrinth of the inner ear. Diagnosis is based on the symptoms and, frequently, a hearing test. Other conditions that may produce similar symptoms include vestibular migraine and transient ischemic attack.