The inner ear functions not only in hearing, but also in the equilibrium of the vestibular system. A disturbance of the inner ear may thus be a source of vertigo or dizziness, a sense of disequilibrium and the feeling that the surroundings or one's own body are rotating. Among the causes of vestibular syndrome of the inner ear (as the cause may also stem from the central nervous system), the most frequent is the presence of lithiasis in the ear canals, which are small crystals in the inner ear. Bouts of vertigo are initiated primarily through changes in the body's position, exacerbated by violent or sudden position changes, or by movements of the head, but with a spontaneous resolution. They may have a serious impact on an individual's life, and are treatable by a doctor or a physiotherapist. Causes may include infections, inflammation or a tumor of the vestibular nerve, and localized injuries.