The vestibular system

Abstract

The vestibular system developed in order to facilitate an organism's movement through its environment. The functional organization of this system is a remarkable network of reflexes and behaviors that allow for the stabilization of visual cues during movement, the establishment of posture during resting states (e.g., sitting or standing), and the maintenance of body balance while in motion. This arrangement necessitates interactions among vestibular structures of the inner ear (the semicircular canals and otolith organs), the ocular motor system, the visual system, the motor control system, as well as proprioceptive input regarding position and movement of the body and limbs. The interplay of these systems allows the individual to accomplish actions ranging from those as seemingly simple as standing still to those as intricately controlled as figure skating or gymnastics, and everything in-between. Disturbances of vestibular function may lead to vertigo, ataxia, and falling. These are among the most common symptoms encountered in clinical medicine, with nearly 40% of all people in the United States experiencing at least one of these symptoms by age 65 years. Although a vestibular disorder can occur at any age, a majority of people in the United States over age 70 years report symptoms of dizziness, imbalance, or falling. Fall-related injuries and the quality-of-life impact of vestibular disorders are the bitter concerns of these patients, as well as their family members. Dizziness and balance disorders constitute significant public health issues, particularly as people are living longer and enjoying good health well into their eighties. The careful assessment of vestibular function is imperative for effective management of the balance-disordered patient.