What is tinnitus?
Tinnitus is an abnormal perception of sound which is reported by patients and unrelated to an external source of sound stimulation. Tinnitus is a very common disorder.
It may be intermittent, constant, or fluctuant, mild or severe, and may vary from a low roaring sensation to a high pitched type of sound. It may or may not be associated with a hearing loss. It is also classified further into subjective tinnitus (a noise perceived by the patient alone) or objective tinnitus (a noise perceived by the patient as well as by another listener). Subjective tinnitus is very common, while objective tinnitus is relatively uncommon. The site of tinnitus may be localized to one or both ears, or described as occurring in the head.
Tinnitus is a symptom much like a headache, pain, or vertigo. With tinnitus, the reported distress is usually subjective and difficult to record and appreciate by others. Some people are minimally affected by the tinnitus and only seem to notice the noise when in a quiet situation. On the other extreme, some can be very disturbed by the perceived noise, describing variable alteration in sleep patterns, poor concentrating abilities, and overall affects on their quality of life, with associated anxiety and distress.
The quality of tinnitus refers to the description by the patient of the tinnitus: it may be a ringing, buzzing, cricket, ocean, musical noise, etc., type sound. The quality may be multiple sounds or a singular sound.
Tinnitus may be produced in one or more locations, referred to as its site of lesion. The cause of tinnitus may be singular or multiple. A peripheral site of lesion (i.e. auditory nerve or cochlea) refers to dysfunction produced within the auditory system anywhere that extends from the ear up to, but not involving, the brainstem. A central site of lesion refers to involvement of the central auditory pathways, beginning at the brainstem and involving other portions of the central nervous system (brain).
Tinnitus is a symptom of neurotologic disease. It may occur with other symptoms of the ear including hearing loss, vertigo, and feelings of ear pressure, or it may occur alone. Patients are often surprised to learn that hearing loss greatly increases one’s chances of experiencing tinnitus. In fact, many times the cause of the tinnitus is attributable to the hearing loss itself. A person’s mood can change the quality or level of disturbance caused by the tinnitus. We find that tinnitus can increase when a person is anxious or under increased levels of stress.
A neurotologic examination and complete inner ear and auditory pathway evaluation is necessary in all patients complaining of tinnitus. The test battery is used to attempt to establish the site of lesion and to rule out any significant pathology, which may require further treatment. There are many causes of tinnitus related directly to the ear, such as simple ear wax. Middle ear abnormalities can also be responsible, including otosclerosis (fixation of the stapes bone in the middle ear), ear infections, and fluid in the middle ear. Inner ear causes include Meniere’s disease, exposure to excessively loud sounds, or sensorineural hearing loss. Tumors of the hearing nerve or middle ear, or other problems in the brainstem or central nervous system, may also cause tinnitus. Finally, vascular abnormalities in the neck, ear, or base of the skull may result in tinnitus.
Since tinnitus often has a high pitch, frequency judgments in this region normally are poor. Frequency discrimination up to approximately 16,000 Hz (which is the upper limit of hearing) is far less exacting than the middle frequency region. In addition, patients suffering from high-pitched tinnitus often have a high frequency hearing loss, which may impair their frequency discrimination. Therefore, test-retest reliability in matching the frequencies of audiometer tones to the pitch of tinnitus may be poor. An attempt may be made, however, to do pitch matching and loudness-matching. In addition, an attempt may be made to determine the maskability of the tinnitus and to measure residual inhibition (i.e., the period of time that tinnitus remains temporarily reduced after a masking sound has been turned off).