How is tinnitus classified?

Updated: Feb 27, 2020
  • Author: Aaron G Benson, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Answer

Tinnitus is classified in many cases into 2 categories. Tinnitus is either objective (ie, audible to anyone in addition to the affected individual) or subjective (ie, audible only to the affected individual). Even though this classification system is used quite frequently, focusing on the etiology of tinnitus is often more useful. The classification is discussed, and then this article focuses primarily on the various etiologies of tinnitus and their respective therapies.

Objective tinnitus is relatively rare. It is sound created somewhere in the body, usually in the ear, head, or neck, and has a muscular or vascular etiology. Muscular tinnitus is observed in several degenerative diseases of the head and neck, including amyotrophic lateral sclerosis. In this entity, the neuromuscular control over the muscles in the ear occasionally deteriorates in an individual with perfect sensory perception. Occasionally, the loss of control results in a repetitive flutter or myoclonus of either the stapedius or tensor tympani muscles. The result is an observable and audible flutter coming from the ear.

Lysis of the tensor or stapedius muscle via a tympanotomy incision is uniformly successful in relieving the symptoms in these cases. However, attention must be paid to the contralateral side. Often, the problem is bilateral, but attention is directed to the louder side. If in fact contralateral problems are present, both muscles should be cut at the same time. This is one of the few cases in otology where operating on both sides at the same time may be considered, decreasing the anesthesia risk and attendant logistic problems for the patient who frequently has problems with anxiety.

Palatal myoclonus is a rare cause of muscular-induced clicking tinnitus. It results from rhythmic discharges from the inferior olivary nucleus by a lesion in the triangle of the Guillain-Mollaret (brainstem). The lesion is usually due to stroke, trauma, encephalitis, multiple sclerosis (MS), or degenerative disease. Some success has been reported with botulinum toxin injection therapy.

The other disturbance that is more frequently observed is an aberrance or abnormality of the carotid artery. Aberrances of the carotid artery are documented multiple times in the literature. The carotid artery can also become ectatic as a person ages or as operations are performed on the carotid. The end result is an artery that often takes a tortuous route through the neck and the ear to reach the brain. Such tortuosity produces turbulent flow in the artery, which can be auscultated by the examiner with each heartbeat.

Similarly, the jugular bulb and the jugular vein can produce a type of tinnitus that is characterized as a venous hum. Often described by the patient as a vibration or a low-pitched sound rather than as a ringing, these sounds seem to be slightly more frequent than the other 2 types of objective tinnitus. Many operations have been described for the treatment of venous hum tinnitus and carotid arterial tinnitus; all of these operations have initially met with success but limited long-term control of the symptom.


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