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| Ear
and head noises, the most common complaints presented to the audiologist
or otolaryngologist, are frequently seen by the neurologist. As many
as 32% of the adult population have tinnitus, with 20% of the population
rating their condition as severe (Vernon 1994). Tinnitus may be
considered a significant symptom when its intensity so overrides normal
environmental sounds that it invades the consciousness. The patient
experiencing tinnitus may describe the sound as ringing, roaring,
hissing, whistling, chirping, rustling, clicking or buzzing, or other
descriptors. Although most patients report the presence of tinnitus to
be constant, others report it to be intermittent, fluctuating, or
pulsating. Tinnitus may be perceived as a high - or low - pitched tone,
a band of noise, or some combination of such sounds.
The perceived loudness of tinnitus in any patient may be intense enough to be highly debilitating. Most patients with sensorineural hearing loss report tinnitus to be a high-frequency tone, but tinnitus associated with conductive hearing loss tends to be low in frequency. However, knowledge of the pitch of the tinnitus is of little diagnostic benefit other than allowing for the gross dichotomy of conductive versus neural pathology. The majority of tinnitus sufferers have a concomitant loss of hearing, which may be either conductive or sensorineural. Only a minority of tinnitus patients have audiometrically hearing sensitivity. Tinnitus may precede or follow the onset of a loss in hearing, or the two may occur simultaneously. Tinnitus is a symptom of an underlying disease or specific lesion when it is perceived above the intensity levels of environmental sounds. It may be the first symptom that brings the patient to a neurologist. The complaint may be an early symptom of a tumor in the internal auditory meatus or in the cerebellopontine angle, a glomus tumor, or a vascular abnormality in the temporal bone or skull. Because tinnitus may be a characteristic symptom of a number of disorders, a complete medical and audiological evaluation is an important initial step in the management process. Subjective tinnitus is a auditory sensation heard only by the patient. It may be present in one or both ears or localized within the head. For most patients, tinnitus is a subjective sensation. This type of tinnitus can result from a lesion involving the external ear canal, tympanic membrane, ossicles, cochlea, auditory nerve, brainstem, and cortex. The most common cause is cochlear disease. Tinnitus associated with Meniere's syndrome is often low-pitched and continuous, and is described as a hollow seashell sound or very loud roaring. Tinnitus with otosclerosis is also low-pitched, is described as a buzzing or roaring sound, and may be continuous or intermittent. Continuous bilateral or unilateral high-pitched tinnitus often accompanies chronic noise-induced hearing loss, presbycusis, and hearing loss due to ototoxic drugs. A number of drugs such as aminoglycosides, quinidine, salicylates, indomethacin, carbamazepine, propranolol, levodopa, aminophylline, and caffeine, may produce tinnitus with or without associated hearing loss (Baloh 1984). Objective tinnitus is far less frequent than subjective tinnitus. It is perceived not only by the patient, but by the examiner as well. Objective tinnitus may be vascular (an arteriovenous malformation or fistula) or mechanical in origin. Objective mechanical tinnitus is due to abnormal muscular contraction of the nasopharynx or middle ear, as may occur in palatal myoclonus. Objective tinnitus of vascular origin may also be a referred bruit from stenosis in the carotid or vertebrobasilar system. Tinnitus may be classified as mild, moderate, or severe. Mild tinnitus is usually noticed only in quiet environments or at bedtime. It is usually not very disturbing, and the patient can easily be distracted from the tinnitus by other stimuli. Moderate tinnitus is more intense and is constantly present; the patient is conscious of the tinnitus when attempting to concentrate or when trying to sleep. Severe tinnitus may disable individuals to the extent that they are is unable to concentrate on little other than the tinnitus itself.
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