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Author Topic: What are the effects of MRI or CT Scan on an Ear Implant?  (Read 2982 times)

Offline Teakhat

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I've had a left stapedectomy...the stapes (or stirrup) has been replaced with a teflon-coated platinum one. I had this done at 61...I'm 64 now and the acuity is astonishing. But I was told...no, WARNED not to get an MRI done. I'm afraid...say...of being found unconscious (fall, car wreck, who knows) and someone would examine me, electronically. I asked what would happen and was told "You won't like it!" Since then, I've had visions of a sparkler going off in my head!!! Okay...what's up with that? Should I be getting a Medic Alert bracelet saying "Don't examine my head?" (BTW: my wife says they'd find nothing, anyway...)  ???
« Last Edit: 02/03/2015 16:57:25 by Georgia »


 

Offline alancalverd

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Re: MRI or CT Scan Effects on Ear Implant
« Reply #1 on: 25/02/2015 10:57:43 »
No problem with a CT, which is preferable for acute trauma anyway, but an MRI could cause problems. A platinum implant won't move in the static primary magnetic field but the gradient and RF fields will induce currents in a conductor, which can produce movement (induction motor) or heating (induction cooker).

We don't get particularly excited by large, secure implants like hips (though they spoil the image), but little things that can move in the head are bad news.

Definitely worth talking to your audiologist and getting a MedicAlert bracelet.
 

Offline Teakhat

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Re: MRI or CT Scan Effects on Ear Implant
« Reply #2 on: 25/02/2015 11:29:49 »
But no sparks??? (Kidding... ;D)

BTW: I was misdiagnosed many, many times as to my hearing loss until someone hit a bull's eye. As a pro musician...the obvious detriment to my hearing made work almost impossible. Subsequent databasing showed my acuity as being on par with a 12 year old percentile. Eh...worth some sparks, I bet. But I didn't realise it might move around a bit. I have no idea of what it would do, to be honest. The innovative...and newest...operation paradigm was no fun to begin with...(akin to a corkscrew being ripped out of your ear, I guess) nor was the six month rebound to "normal" Hz recognition by my brain...

Ok. Medic Alert bracelet makes sense...
 

Offline alancalverd

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Re: MRI or CT Scan Effects on Ear Implant
« Reply #3 on: 26/02/2015 20:08:38 »
Pro medical physicist, amateur musician - hence much sympathy and understanding! Best of luck with your continued rehabilitation.
 

Offline Teakhat

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Re: MRI or CT Scan Effects on Ear Implant
« Reply #4 on: 27/02/2015 03:53:36 »
Thanks for that reply, matey. But there was a VERY weird side effect that I didn't realise having to do with the perception of sound in the "new ear". Once all the cotton wadding gets removed after perhaps a week...hearing is immediate...but odd. In quiet moments, I could swear there was that high pitched bugle made by a mosquito as it hovers close to your ear. It only occurred as other speaking was being carried on. What was happening was the new stapes was functioning properly...but my brain was still used to augmenting the sound from the old and heavier (from plaque) natural stapes. Over the next six weeks, this sound crept lower and lower until it matched the reality of what I was hearing. Oddly...and wonderfully...when my ears were exact intervals apart...like going through an upper 5th on one side...it was actually awesome!!! But in between exact intervals was like scraping a fork on a dinner plate. My best hearing moments were when a container vessel blasted a basso profundo note that was a 3rd out...and uhnttumy sandals slapping up at my heels in an echoey parking garage...up a 5th.

On a serious note...if anyone has one-sided hearing loss...talk to an ENT surgeon that is up to speed with the pioneering work done by Professor Bruce Black in Brisbane. You will hear again. Amazing........
 

Offline alancalverd

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Re: MRI or CT Scan Effects on Ear Implant
« Reply #5 on: 27/02/2015 08:22:59 »
Now that's really fascinating. I wonder if there's a form of tinnitus, or even "voices in the head", that is due to the brain compensating for a failing ear? And Oz is deffo the place for the deaf - most cochlear implant technology seems to originate Down Under.
 

Offline evan_au

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Re: MRI or CT Scan Effects on Ear Implant
« Reply #6 on: 27/02/2015 10:44:47 »
Quote
I didn't realise [the stapes] might move around a bit

The stapes is one of a chain of three tiny bones in the ear, which conduct sound from the eardrum to the inner ear. It performs an impedance-matching function from the air to the fluid-filled cochlea, allowing more efficient transfer of sound (the bell on a trumpet performs a similar impedance-matching function; this is one reason a trumpet sounds louder than a flute...).

The stapes must move to conduct sound.

The stapes is very light, so rapidly changing magnetic fields will induce a current in the metal prosthesis, and cause it to oscillate like a loudspeaker. This will feed loud sounds directly into the cochlea.

There is a muscle in the middle ear that can break the chain of conduction through these bones, blocking sudden loud sounds. However, this muscle gets tired very quickly, so it can't protect you for very long.
 

Offline Teakhat

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Re: MRI or CT Scan Effects on Ear Implant
« Reply #7 on: 28/02/2015 05:31:57 »
Thanks for that. I'm afraid that I know very little of "what's in there"...nor do I want to look!

I had TEN years of one bad diagnosis after another UNTIL one GP simply said "I don't know...but let's find out." First...I went to an ENT guy where an anaesthetic was sprayed up into my eustachian tube (AKA: pharyngotympanic tube) from the inside of my mouth. Next, a camera went in and there was no sign of any pathogens in the middle ear. Next...to an audiologist to test my nerves, bone conduction and how "floppy" my ear drums were. Again...no problems. This narrowed it down to the hammer/anvil/stirrup. But there are statistics that correlate all those other audiology tests to whether or not it was the stapes...and, indeed, it was. There is a two-day hospital stay to have the procedure done. The pain...for some...is minimal afterwards. Me? I would have preferred death to the ache that followed...until they gave me heavy pain relief. Like I said...imagine a cork screw being screwed in...then ripped out of your ear!!! But that lasted only a day. Next trip was a week later to get the cotton taken out. Geez...how they got a whole box of cotton in there still stumps me! The surgeon uses a few instruments to go around your eardrum and shove it to where it belongs. (More opiates recommended!) But there it was: SOUND! I could HEAR! Awesome..........

BTW: this problem is the MOST mis-diagnosed of hearing loss...and one that will bring hearing acuity back to like when you were a kid!!! The innovations developed by Professor Bruce Black (Brisbane)...who actually did my own surgery...gives him a free pass at The Pearly Gates.  ;)

Indeed...many medical advances are Australian. I'm an expat American...and can say that life on "Earth's Second Moon" is a wonder every day.........

God Save The Queen
 

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Re: MRI or CT Scan Effects on Ear Implant
« Reply #7 on: 28/02/2015 05:31:57 »

 

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