Vertigo, a symptom of a balance disorder, is the illusion of movement when no movement is present. This can be caused by a problem of the inner ear balance mechanisms, or by a problem in the brain. While usually harmless, vertigo can be a sign of a serious condition if accompanied by difficulty in speaking or walking, severe headaches, or double vision. Even when no other symptoms are present, it is always a good idea to consult a doctor. The same is true if the episodes worsen over time or if new symptoms appear.