Infections (viral or bacterial), head injury, disorders of blood circulation affecting the inner ear or brain, certain medications, and aging may change our balance system and result in a balance problem. Individuals who have illnesses, brain disorders, or injuries of the visual or skeletal systems, such as eye muscle imbalance and arthritis, may also experience balance difficulties. A conflict of signals to the brain about the sensation of movement can cause motion sickness (for instance, when an individual tries to read while riding in a car). Some symptoms of motion sickness are dizziness, sweating, nausea, vomiting, and generalized discomfort. Balance disorders can be due to problems in any of four areas:

• Peripheral vestibular disorder, a disturbance in the labyrinth.
  
  
• Central vestibular disorder, a problem in the brain or its connecting nerves.
  
  
• Systemic disorder, a problem of the body other than the head and brain.
  
  
• Vascular disorder, or blood flow problems.