Elsewhere on the Internet there is a discussion about various indications for undergoing an MRI to rule out an acoustic neuroma in people with tinnitus. I feel that this issue is an important one, and I disagree with some of the (well-intended) posts in that thread. I will explain why below.
There are two indications for ordering an MRI in patients with tinnitus.
The first is the presence of asymmetrical tinnitus with or without asymmetrical hearing loss in the absence of a reasonable explanation for the asymmetry. (A right-handed hunter who does not use ear protection and develops tinnitus in his left ear after shooting would not need an MRI because that is the ear closest to the barrel of the gun.) A couple of the participants in the above-referenced discussion feel that the asymmetrical tinnitus needs to be gradually increasing over time (presumably indicating “growth of the tumor”) – otherwise there is no reason to suspect an acoustic neuroma. In my opinion this logic is faulty for two reasons. The first is that the loudness of tinnitus is not a measure of size of the tumor. That is, acoustic neuromas can, and often do, grow in size without a change in tinnitus. The second is that the smaller the acoustic neuroma at the time it is first diagnosed, the greater the number of therapeutic options and the lower the complication rate. The last thing a physician should be doing is taking the risk of delaying the diagnosis of a tumor immediately adjacent to the brain, thereby decreasing therapeutic options and increasing morbidity! Consequently, it would be highly irresponsible for a physician not to order an MRI in a person with unexplained asymmetrical tinnitus on the basis that the tinnitus is not gradually getting worse.
The second indication for ordering an MRI in a person with tinnitus is if that person is worried and anxious about the possibility of an acoustic neuroma even though the tinnitus is symmetrical. Certainly the doctor should try to reassure such patients without ordering an MRI, but if that fails, refusing to order an MRI because the tinnitus “is not bad enough” (or some such thing) is irresponsible for two reasons. The first is that one of the keys to habituation of tinnitus is the patient’s recognition that the tinnitus does not somehow represent a threat. And sometimes the patient simply needs the reassurance afforded by an MRI that the tinnitus is not caused by a “brain tumor” in order to stop seeing it as a threat. The second reason it would be wrong to withhold an MRI in a worried and anxious patient who cannot otherwise be reassured is because physicians are supposed to address the basic psychological needs of their patients as well as the physical needs. To do otherwise is simply cruel!
Fortunately Medicare and most carriers in the US will cover the cost of an MRI if the physician writes “tinnitus” as the reason for the test. (I presume that government entities like the NHS in the UK will do the same.) And it is absolutely not an overuse of medical resources for a physician to order an MRI for either of the indications in the two preceding paragraphs.
Once a decision is made to order an MRI in a person with tinnitus, the proper test for the physician to order is “MRI of the brain and IAC’s (internal auditory canals) with and without gadolinium to rule out acoustic neuroma.” Of course ear protection should be used during the exam because the MRI machine is typically quite noisy.