Photo credit: liz west licensed under CC BY 2.0
by Daniel Fink, MD, Chair, The Quiet Coalition
MRI noise is in the news in two recent reports.
People magazine reported the story of a woman who suffered permanent auditory damage from an MRI, developing hyperacusis (a sensitivity to noise, which causes pain) and tinnitus. The Quiet Coalition’s Bryan Pollard, an expert on hyperacusis, is quoted in the article.
And researchers from SUNY Buffalo and China wrote about MRI noise in The Hearing Journal.
Standard MRIs produce noise in the 110-115 decibel range, and newer more powerful MRIs are even louder. Knowing this, I have several quibbles with the information in The Hearing Journal article. Namely, the article cites occupational noise exposure standards, but these use A-weighted decibels (dBA) to reflect the frequencies of human speech. MRI noise is low frequency noise, so occupational noise limits may not protect hearing adequately. And occupational standards are not safe standards for the public. At least 25% of workers exposed to sound at occupational noise exposure standards will develop hearing loss.
Most importantly, for many people the auditory damage caused by MRI noise isn’t hearing loss but tinnitus and hyperacusis, as in the People magazine article. Exactly how noise causes tinnitus and hyperacusis isn’t yet known, but the mechanisms are likely different from cochlear hair cell damage causing noise-induced hearing loss.
Finally, the authors talk about temporary auditory damage, but many researchers think that any temporary auditory changes indicate that permanent damage has been done.
I can’t find any large-scale studies of auditory problems after MRIs–the equipment manufacturers wouldn’t be excited about funding such a study, and radiologists are interested in the image, not in the patient’s hearing–but anecdotal reports from audiologists indicate that this is a problem for too many people undergoing diagnostic MRIs.
So if you need an MRI, be sure to ask for “dual protection”– ear plugs and ear muffs. NIOSH recommends dual protection for noise exposure over 100 dBA.
And if you suffer auditory damage from an MRI, be sure to file a report with the FDA. That’s the only way the government will be induced to issue appropriate patient safety regulations.
