Somatic Tinnitus

When the quality of tinnitus is nonspecific (such as buzzing, tonal, hissing, humming, ringing, roaring, rushing, whistling and whooshing, crickets), establishing a cause for the tinnitus is a challenging problem. An experienced clinician has observed, “If the probability is assessed as being over 50% that a particular condition is causing the tinnitus, ...most cases of tinnitus would have to be classified as ‘unknown’” (ie, idiopathic).1 Among the reasons why establishing the cause for nonspecific tinnitus is so difficult is the fact that tinnitus is common in the general population presumably because it can be a normal physiologic phenomenon. At one extreme is the study by Heller and Bergman, who found that 94% of people they studied had tinnitus.2 A more recent study found that although 19% of adults, when questioned, reported tinnitus, when the same individuals were then taken to a quiet room, another 28% described some tinnitus, so that a total of 47% described nonspecific tinnitus.3 Another reason contributing to the difficulty in establishing a cause for nonspecific tinnitus is that for any pathologic process associated with tinnitus, not all subjects with this diagnosis will, in fact, develop tinnitus. An extreme case is individuals who are deaf; 80% have tinnitus, but 20% have no tinnitus.4 Hence, the presence of tinnitus and the existence of a pathologic process by themselves do not imply that the two are related. Another consideration in attempting to establish a diagnosis to account for a patient’s tinnitus is that the cause of the tinnitus may be multifactorial. A closely related idea is that tinnitus can be considered a threshold phenomenon,5 such that whereas any one factor, such as chronic progressive hearing loss, may not be sufficient to elicit a tinnitus complaint, two or more factors may synergistically lead to the tinnitus becoming symptomatic. For example, it is well established that the prevalence of tinnitus increases with C H A P T E R 9