[Differential diagnosis of tinnitus and vertigo. A review].
Tinnitus and vertigo, two common neurological complaints, often challenge the physician's ability with respect to possible etiology. Objective tinnitus can result from an abnormally patent eustachian tube, from tetanic contractions of the muscles of the soft palate, or from vascular abnormalities within the head or neck. Subjective tinnitus refers to lesions involving the external ear canal, tympanic membrane, ossicles, cochlea, auditory nerve, brainstem, and cortex. As many as 50% of patients with tinnitus do not exhibit associated hearing loss; in these patients, the cause of the tinnitus is rarely identified. An illusion of movement is specific for vestibular system disease--a peripheral or central location depending upon associated audiologic and neurologic symptoms, respectively. However, a presyncopal, light-headed sensation is most commonly associated with diffuse cerebral ischemia: in the young patient, this may be caused by a hyperventilation syndrome; in the aged individual, this can result from diffuse atherosclerotic cerebrovascular disease and decreased cardiac output. Postural and gait imbalance associated with acute vertigo indicates a unilateral peripheral vestibular or a central vestibular lesion; if vertigo is absent, either a cerebellar, proprioceptive, or bilateral peripheral vestibular lesion is likely. Transient oscillopsia suggests unilateral peripheral vestibular lesions. Permanent oscillopsia indicates a bilateral peripheral vestibular lesion or--in the absence of severe vertigo--brainstem or cerebellar damage.