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The Consumer Handbook on Tinnitus

Chapter 1
Normal Operation of the Balance System in Daily Activities

Neil T. Shepard, PhD

    Professor of Otorhinolaryngology
    University of Pennsylvania Medical School

The sensation of dizziness, whether that is a spinning of your world, lightheaded feeling, imbalance or a combination of these symptoms constitutes a significant public health problem in the United States and elsewhere. Estimates of the number of persons in the U.S. seeking medical care for dizziness range as high as 7 million per year. Approximately 30 percent of the U.S. population has experienced episodes of dizziness by age 65. There are no indications that the problems of dizziness and imbalance are diminishing, particularly as the population ages. Having an understanding of the daily function of the balance system is important in the comprehension of what causes symptoms of dizziness and imbalance. This knowledge also helps in the understanding of how patients with these complaints are evaluated and treated. This chapter presents information about how the normal balance system is supposed to function. It is intended to support your reading of the remaining chapters that discuss specific disorders of balance and dizziness and techniques for evaluation and management of those conditions.

What is the Balance System?

No single structure makes up or controls balance system function. Rather, the balance system consists of three structures that gather information about how we are moving, oriented to gravity (standing on our feet or our head) and how the world around us is moving. These three input (sensory) structures are:

  • the balance organ portion of the inner ear, called the vestibular endorgan (the other portion of the inner ear is involved with hearing);
  • our eyes; and
  • information from the soles of our feet and our joints (especially the ankle, knee, hip and neck) called proprioception.

The input information is brought together at a level in the back of the brain in two specific structures called the brainstem and the cerebellum. The input information results in routine responses for eye movement, maintaining upright stance and perceptions about how you are moving.
When considering function of the balance system, it’s helpful to look at the major purposes that the system attempts to accomplish. You can view these purposes as three distinct areas:

Perceptions of how we are oriented in a gravitational field (standing on our feet or our head), the direction and speed of movement and when a change in the movement occurs. Being able to . . .