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January 22, 2016

Where Does Tinnitus Come From? Ear or Brain?

It is invariable that when a patient comes to an ENT office complaining of tinnitus or ringing of the ears that only they can hear, that they feel this problem stems from purely an inner ear problem. However, the truth is WAY more complicated in that this phantom ringing actually comes more from the brain rather than the ear and as such, treatment (if any possible) is geared more towards the brain rather than the ear.

The analogy I often use to explain this phenomenon is phantom limb pain... For example, when a person gets their leg cut off for one reason or another, it is not unusual for that patient to experience phantom limb pain... i.e., suffer an itch of a foot they no longer have.

The implication being that phantom limb pain is not a problem of the missing leg itself... but rather the brain that still thinks you have a leg... as well as an itch on the foot you no longer have.

Similarly, tinnitus is when the brain thinks you are hearing a sound that doesn't exist in reality. Think of it as phantom limb "noise".


To further prove that tinnitus is actually more a brain problem than an ear problem... studies have been performed to see if the tinnitus persists even when the inner ear or hearing nerve is surgically destroyed or removed (due to tumor, disease, etc). After all, if the tinnitus truly is an ear problem, than removing the inner ear or hearing nerve should resolve the tinnitus, right? But that's not what happens.

In a 1981 published article, the researchers reported that when the hearing nerve itself was removed in 414 patients, only 40% reported improvement in their tinnitus. Of 68 patients whose hearing nerve was cut, improvement in tinnitus occurred in 45%, while 55% reported the condition to be the same or worse. In patients undergoing middle cranial fossa section of the vestibular nerve for vertigo or dizziness, most reported the tinnitus to be the same but a significant number felt that it was worse.

A literature search performed in 2002 identified 18 papers mentioning tinnitus status after vestibular nerve section, describing the experiences of a total of 1318 patients. They found that tinnitus worsened after surgery in about 16.4% (standard deviation 14.0). Tinnitus remained unchanged in 17% to 72% (mean 38.5%, standard deviation 15.6), and tinnitus improved in 6% to 61% (mean 37.2%, standard deviation 15.2).

Clearly, the ear is not the sole culprit when it comes to chronic tinnitus. Though the ear may have played a role in the initiation, the brain potentially plays a much more dominant role in tinnitus persistence.


References:
Tinnitus: surgical treatment. Ciba Found Symp. 1981;85:204-16.

The effect of vestibular nerve section upon tinnitus. Clin Otolaryngol Allied Sci. 2002 Aug;27(4):219-26.
Fauquier blog
Fauquier ENT

Dr. Christopher Chang is a private practice otolaryngology, head & neck surgeon specializing in the treatment of problems related to the ear, nose, and throat. Located in Warrenton, VA about 45 minutes west of Washington DC, he also provides inhalant allergy testing/treatment, hearing tests, and dispenses hearing aids. Google+ Christopher Chang, MD Bio

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