Is Your Metal Implant MRI Safe? There's a Website for That...

Although one could always contact the manufacturer or surgeon who performed your metal implantation directly to determine whether it is MRI safe or not, there's also a website that contains a comprehensive database of metal implants and how compatible they are with MRI scans.

Who knew that certain metal implants are compatible with MRI scans up to a certain strength?

Who knew a metal implant that may not necessarily be compatible with MRI, but given enough time after implantation (usually 6 weeks), it is still safe to get an MRI scan?

Check this website www.MRIsafety.com out!

The actual searchable list of implants is here.

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Bruce Jenner of the Kardashians with Hearing Loss Brain Tumor Scare

Image by jla0379 from Wikipedia

This past weekend, fans of the TV show Keeping Up with the Kardashians found out that Bruce Jenner had what most likely was an asymmetric nerve hearing loss in his high frequencies when he had a hearing test done that lead to a brain tumor scare.

What this means is that his ability to hear was much worse in one ear compared with the other... and it was due to nerve damage rather than earwax or fluid in the ears.

Whenever there is this type of nerve hearing discrepancy between the right and left ears, there is concern for the possibility of a benign brain growth called an acoustic neuroma. As this tumor gets larger, it compresses the hearing nerve causing progressive hearing loss on just one side.

Whenever a significant difference in nerve hearing is found on a hearing test, an MRI scan of the internal auditory canal is performed to look for this or other related tumor. Statistically, there is only a 5-10% risk of an acoustic neuroma with the presence of an asymmetric nerve hearing loss.

Fortunately for Bruce Jenner, no tumor was found and hearing aid placement was pursued.

Now, is it absolutely necessary that an MRI be performed? No, though it is the BEST test to further evaluate.

Alternatively, one can perform serial hearing tests every 6-12 months to monitor for any progressive hearing loss... and if present, than pursue an MRI scan.

One can also get a specialized test called an auditory brainstem response (ABR) which measures how quickly a sound gets transmitted to the brain. If a tumor is present, the signal is delayed whereas if no tumor is compressing the hearing nerve, the signal reaches the brain at a normal speed.

Of course, if the ABR comes back abnormal, than an MRI scan would be recommended as the next step.

Read more about asymmetric hearing loss.

Source:
‘KUWTK’ Recap: Bruce Jenner Might Have A Brain Tumor. Charter 6/24/13

BRUCE JENNER FEARS BRAIN TUMOR IN HEARING LOSS WOES—WATCH THE NEW KARDASHIANS CLIP. E Online 6/20/13.

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How Much Radiation Exposure Occurs with a CT Scan? X-ray? Sunlight?

A common concern now is how much radiation exposure occurs with common radiological testing such as x-rays and CT scans, especially given the small increased risk of cancer with accumulated exposure over years.

Of note, ultrasounds and MRI scans do not emit radiation. MRI scans use magnets while ultrasounds use sound waves in order to obtain imaging information.

So, here's a chart comparing such tests with common environmental radiation exposure such as sunlight. Information taken from www.X-RayRisk.com:

Radiation	Amount
Sunlight (high-altitude city)	6 mSv per year
Sunlight (sea-level city)	3.1 mSv per year
Frequent Flyer	1 - 6.7 mSv
Single Airflight coast-to-coast	0.01 - 0.03 mSv
Smoke 20 cigarettes per day	53 mSv
CT Chest	7 mSv
CT Head	2 mSv
Nuclear Stress Test (Technicium)	9.4 mSv
Nuclear Stress Test (Thallium)	40.7 mSv
Barium Swallow	5 mSv
Mammogram	0.4 mSv
Chest X-ray	0.1 mSv
Dental X-ray (Bitewing)	0.02 mSv

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Sinus Mass Chance Finding (Incidentaloma)

The New York Times published a great story on the dreaded incidentaloma on Jan 17, 2013. An incidentaloma is essentially a chance finding of a mass most likely benign, that was incidentally discovered on a CT or MRI scan ordered for a completely different reason.

With such incidentalomas, it leads to patient anxiety causing physicians and surgeons to order even more tests and procedures (which themselves may lead to other incidentalomas). The vast majority of such incidentalomas are "nothings" without any significance, but hard to persuade patients otherwise at times.

In the ENT world, incidentalomas are very common when CT and MRI scans are performed of the head for a headache, stroke, eye pain, dizziness, or some other non-sinus related complaint.

In the report, there is the statement of:

"There is an opacified mass inside the right maxillary sinus cavity [or some other sinus cavity] two centimeters [or larger] in size."

Compare the above CT scan (red arrow pointing to the mass) with a normal CT scan of the sinuses below:

IF symptoms are localized to the corresponding mass on the CT/MRI scan, than further management which may include surgery can be pursued.

However, the vast majority of patients have absolutely NO symptoms localized to the corresponding abnormality. Radiologists and ENTs report that such a mass is most likely a benign mucosal inclusion cyst for which there is no significance and nothing more needs to be done.

However, some patients due to cancer concerns, even insist on having surgery to get it removed, even in spite of the risks associated with surgery including brain fluid leakage, eye damage, etc.

I personally usually insist a patient get a 2nd opinion prior to any surgical intervention for an incidentaloma if I'm pressured to "do something" when my gut feeling is to "do nothing."

Source:
The Fallout of a Chance Medical Finding. New York Times 1/17/13

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What is Asymmetric Nerve Hearing Loss

Given my last blog article regarding an ENT who got sued for not doing an MRI after audiogram showing an asymmetric hearing loss, the question that should be on everybody's mind is what IS asymmetric nerve hearing loss on a hearing test?

I am sad to report that there is no clear consensus on what is asymmetric nerve hearing loss.

First of all, at its most basic definition, asymmetric nerve hearing loss is when hearing is worse in one ear when compared with the opposite ear due to nerve damage.

Technically, hearing should decrease equally on both sides over time, but when one side gets worse faster than the other, it can cause concern because:

1) A tumor can be pressing against the nerve causing it to slowly fail faster than the other ear's nerve which is not compressed.
2) There is a loud noise history with asymmetric exposure to the ears. One example is hunting with a rifle where the left ear would repetitively get noise-induced damage from the gunshot in a right-handed shooter.
3) Bad luck

The conflict is at what point is an asymmetry considered significant enough to warrant a workup which may include an MRI scan of the head and/or auditory brainstem response (ABR)? Also, for a given patient history, a physician/patient may elect to recheck hearing bi-annually to monitor for asymmetric progression rather than pursue workup immediately (further studies being pursued only if asymmetry progresses over time).

Is asymmetry defined as 1 decibel difference between ears? Is it 50 decibel difference?

Even if the decibel difference is agreed upon, than over what frequencies? All of them or just a few of the frequencies?

So for the purposes of a "medically" significant asymmetric nerve hearing loss, the definition must define not only HOW big the difference in hearing loss is present between ears but also at what frequencies.

In one paper, it is 15 decibels at just 3000 Hz.

In another paper, it is 20 decibels at any two adjoining frequencies (or 15 decibels at two adjoining frequencies between 2000 and 8000 Hz).

Get this... even when criteria is defined, one study found substantial disagreement among five expert judges on what hearing tests they considered showed asymmetry.

Even insurance companies are jumping into the fray in what they considered significant enough to warrant covering the MRI scan. At one point when I ordered an MRI scan of the head for what I thought was a significant asymmetry found in one patient's hearing test, the insurance company denied the test citing "that there needed to be other neurological deficits PLUS the asymmetry seen on hearing test before MRI scan would be authorized".

I personally pursue further workup using the 20 decibel difference at two adjoining frequencies OR 30 decibel at one frequency.

Assuming medically significant asymmetric hearing loss has been defined and is present...

What are the chances of something bad going on (i.e., tumor) when an MRI scan of the head is ordered for asymmetry found on hearing test?

Less than 10% (depending on study, can be as low as 1-4%).

Given such a low positive yield on testing, why even pursue a MRI scan?

Because of defensive medicine to avoid being named in a lawsuit if the affected patient just happens to be within that 10% found to have an acoustic neuroma.

Indeed, in one study, 40% of ENTs stated medico-legal concerns factored into their decision to get an MRI scan of the head.

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ENT Sued for Malpractice for Hearing Loss Due to Acoustic Neuroma

A patient has sued an ENT for failing to workup an asymmetric sensorineural hearing loss (nerve hearing loss greater in one ear compared to the opposite ear) that allegedly deviated from standard of care that ultimately led to permanent hearing damage and facial paralysis.

Since January 2008, the plaintiff saw the defendant ENT who performed 3 audiograms that revealed an asymmetric sensorineural hearing loss. In 2010, the plaintiff suffered a sudden sensorineural hearing loss at which time an MRI scan of the head was performed revealing a "large" acoustic neuroma (benign tumor of the hearing nerve).

Resection of this tumor resulted in a visible facial droop, permanent hearing loss, and cognitive deficits due to partial removal of brain tissue.

According to plaintiff, had the ENT performed MRI scan when asymmetric sensorineural hearing loss was first detected (presumably back in 2008), he never would have suffered from these defects.

Read about the case here.

Normally, if and when asymmetric sensorineural hearing loss is first detected, some type of workup is typically performed (auditory brainstem response and/or MRI scan of the head) unless there are extenuating factors present in the history. Such extenuating factors include old age and/or significant loud noise history that may lead to asymmetric hearing loss such as shooting (which often causes left greater than right nerve damaged hearing loss in right-handed shooters).

Apparently THREE audiograms were performed over time. If there was progressive worsening of the asymmetric sensorineural hearing loss, than MRI should have been performed and/or at the very least an auditory brainstem response testing (ABR). IF the audiograms showed stable asymmetry over time, it can be argued that absolutely no further workup is needed.

The key question in this case is had the defendant ENT obtained an MRI in 2008 when asymmetric sensorineural hearing loss was first detected, the acoustic neuroma would have been discovered earlier thereby preventing the permanent hearing loss he later suffered in 2010 along with facial paralysis and cognitive defects that occurred after surgical resection.

A couple problems with this line of reasoning from a purely medical perspective:

1) Acoustic neuromas grow at a rate of 1mm per year on average. As such, if the acoustic neuroma was large in 2010... it most certainly was large in 2008 being only 2mm smaller.
2) As such, surgical resection of the "large" acoustic neuroma had it been performed in 2008 probably would have resulted in the same outcome of permanent hearing loss, facial paralysis, and cognitive defects.

Hypothetically, had the MRI been performed back in 2008 revealing the large tumor, the options that would have been presented to the defendant patient would be:

1) Surgery
2) Radiation
3) Observe

Given it is established that the acoustic neuroma was large even in 2008, any type of intervention whether surgery or radiation, most certainly would put at risk the facial nerve which runs alongside the acoustic neuroma. Permanent facial paralysis and hearing loss most certainly is not an uncommon outcome after intervention.

One could even argue that in all likelihood, ALL the defendants current complaints would have occurred 2 years more quickly had the MRI scan of the head and subsequent intervention been performed.

Observation would have only lead to the current sequence of events.

As such, did malpractice occur?

Given the same outcome would probably have occurred, the defendant physician may argue that malpractice did not occur.

Should the defendant ENT have ordered the MRI scan of the head back in 2008 when an audiogram he obtained showed the asymmetric sensorineural hearing loss?

Probably though this might be debatable depending on patient's prior noise history and exact audiogram findings. Most definitely if the audiograms revealed a progressive worsening of the asymmetry over time. Most likely not if the audiograms remained the same over time.

Would knowing there was an acoustic neuroma present in 2008 have changed the patient's ultimate outcome?

Probably not given the large size.

Source:
Couple sues physician for medical malpractice. The West Virginia Record 7/10/12

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Head MRI and CT Scans Explained!

@ENTHouse brought to my attention a FANTASTIC website that literally identifies and goes through all anatomic structures on every slice of a CT or MRI scan of the head.

Sinus cavities, blood vessels, nerves, bone, suture lines, etc...

Wish I thought of doing it first...

It may be a bit confusing for a layperson, but if you have a copy of your CT/MRI scan and wonder where the maxillary sinus or optic nerve is located on your scan, check this website out and you probably can figure it out!

headneckbrainspine.com

Check it out!

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