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Anesthesia

Side effects of anesthesia

12/19/2006

Question:

About a week after surgery to repair my hernia, I started hearing a high pitched ringing in my left ear. The ringing has been continuous for almost 3 months now. I have been examined by an ear, nose, throat specialist and all appears normal so far based on hearing test results and his examinations. A friend who is a nurse indicated that the ringing could be a side effect of the anesthetic. Is this a possibilty, and if so, will the ringing eventually go away? Thank you.

Answer:

The continuous ringing noise is known as "tinnitus". There are many possible causes, but often no cause is found. Tinnitus can be an extremely annoying or even disabling condition. You do not say what kind of anesthesia you had for your hernia repair. Hearing loss after spinal anesthesia has been described. Sometimes, along with the hearing loss tinnitus may be experienced. Although this phenomenon of hearing loss after spinal anesthesia is generally felt to be uncommon, studies in which hearing have been accurately measured by audiometry suggest an incidence of between 0.2 and 8%. The hearing loss is usually mild, and probably unnoticed in the majority of cases, which get better on their own.

There is no link between general anesthesia and tinnitus that I am aware of. Local anesthetics, if absorbed into the bloodstream quickly or in large amounts, can cause transient (temporary) tinnitus. When I say transient, I mean nor more than a few seconds or minutes. Whenever epidural anesthesia is administered, a "test" dose is given and we inquire about tinnitus to make sure that the anesthetic is not accidentally being injected into a blood vessel.

Whenever new symptoms develop after a person has had anesthesia there is a natural tendency to believe that the anesthesia is somehow linked to, or a cause of, the new problems. Let's look at your example. Tinnitus occurs in the general population with a prevalence of 1 in 10 to 1 in 20 persons. So, in America, more than 30 million people have, or have had, tinnitus! About 40 million people have surgical procedures in America each year. Without doing the actual math, you can probably see that the chances of one of the 40 million people by chance developing tinnitus after anesthesia is not that small. To sort this issue out scientifically we would have to take a random sample of the population and compare them to a similar random sample of people who undergo anesthesia, then follow them to see how many develop tinnitus.

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Response by:

Gareth S Kantor, MD Gareth S Kantor, MD
Assistant Professor of Anesthesiology
School of Medicine
Case Western Reserve University