ANA Discussion Forum
General Category => Inquiries => Topic started by: sharonov on June 24, 2009, 09:48:11 am
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I just posted this..........in the wrong place. Well, here it is again:
I've been reading this site more and more as I face potential (probable) surgery, and have a question. With MRI imaging showing the tumor from various angles, why do so many people say, "when they got in there they found the tumor to be xxx instead of x?" You'd think the MRI would nail it! I know, I have 0 medical training, but also, why can't they tell if the doggone thing is wrapped around another nerve before they get in?
Second question, since ANs can grow and killl you and do multiple bad things, why is it not classified as cancer? Is it because cells don't break off and go other places and just stay happily on the 8th cranial nerve and are just overgrowths of schwannoma cells? And did I just answer my own question?
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Ya, you did kind of answer your own question. Neuroma's aren't cancerous, and are only life threatening if you ignore them and let them get too big. As for you other question, I have wondered the same thing. I'm not sure why MRI's don't show the whole picture, but they don't. They had no idea my tumor was on the facial nerve and not the acoustic nerve so I was totally unprepared for total facial paralysis. Not fun. So I guess modern medicine still have a ways to go. But I'm grateful I was born now and not 100 years ago when the survival rate from this tumor was about 14%, NOT GOOD.
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On the issue of size, it is often a matter of how it is measured. For larger tumors on the CPA usually the radiologists will only report the measurements of the (almost spherical) portion that extends on the CP angle. That is, they do not count the portion that is located inside the internal auditory canal.
However, upon removal, very often the "largest" measurement is reported, which includes the portion inside the IAC. Thus the discrepancy. A tumor with say 2.5 cm in the CPA, can easily be more than 3 cm once you count the IAC portion, and this can be easily confirmed from the MRI images, by doing both measurements. So it is not a question of inaccuracy of the MRI (which can be in the range of 1-2 mm), as much as a question of how the measurement is reported.
The tricky part is that the IAC portion beeing so tiny, it does not really contribute towards the overall volume, thus in terms of volume it does not really count.
Marianna
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I've been reading this site more and more as I face potential (probable) surgery, and have a question. With MRI imaging showing the tumor from various angles, why do so many people say, "when they got in there they found the tumor to be xxx instead of x?" You'd think the MRI would nail it! I know, I have 0 medical training, but also, why can't they tell if the doggone thing is wrapped around another nerve before they get in?
head MRI's can have many different influences that affect the "size" measured, ie: there is a total margin of error on head MRI's of +/-2mm, that different technologies of MRI machines can come into play, as well as how the "slices" are done of each "view". Dr's have repeatedly noted that the only true way to determine the size of the MRI is to physically put your hands on it to measure... yet, different radiologists that read films as well as dr's that remove them each measure their own different way (side to side, angle to angle, etc).
Thus, keeping in mind the "total margin of error" of +/-2mm... many factors can make the different in the MRI measurements noted.
Hope that helps.
Phyl
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Hi there,
I am not sure that I can answer your question as now I have one myself. I think Marianna made a good point about measuring. My results showed 1.6 x 1.5 x 1.9 originating from the CPA and working downwards 8mm into the ICA. The Neuro said it was still small. But does this mean that the 8mm is part of the first equation or it's in addition. If it's in addition, it makes it's larger and the Neuro did not give my that impression, but again I was in such anxiety as well when I was there that I didn't even clarify it. The only thing I said was that I didn't want to lose the window of opportunity of radiation treatment since I am in Watch and Wait and he replied that I still had about 4mm to go. I hope I didn't confuse you more but I am definitely more confused. Hope someone clarifies further for both of us.
Vivian
Vivian
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Hmmm hard to tell, but when you see three measurements, like 1.6x1.5x1.9 they almost always refer to the "spherical" portion, in the CPA. There is a tiny tail that goes into the IAC, protruding from this, and this is usually a separate measurement (not included above). However in terms of radiation, only the first set of measurements (the ones in the CPA) matter, because they are the ones that define the total volume that needs to be radiated. So, like your doctor said you are well within the margin for radiation.
It is very difficult to make sense of all this, and I only understood it once I started doing my own measurements, because the various doctors drove me nuts with the differences they were reporting.
On the other question that Sharon had on how difficult is to differentiate the different types of tumors by MRI, the reason is that they all appear to be similar and may originate from similar locations (remember that the facial nerve runs parallel to the vestibulocochlear nerve inside the IAC). So sometimes it may be difficult to tell apart a facial from an acoustic schwannoma or even a meningioma. This can be done only upon histological examination folllowing surgery.
Marianna
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Thanks Marianna,
It looks like you have done your research. I almost started freaking out again. I'm so glad I found this support group. Imagine if we had to call the doctor everytime we had a question.
Vivian
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or remeber that the system may make an error. i had a ck dr read the radiologist's report to me and say that it has grown huge. the next day - in Neuro surgeon's office, he said that he measured it and the report was wrong. the radiologist used a tape recorder to send info to typist and the decimal was misplaced when it was typed.
just a sleepless night - and a few bucks out of the pocket - oh well ... i bet that it did not botehr the dr a bit!!!!
carter
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since ANs can grow and kill you and do multiple bad things, why is it not classified as cancer? Is it because cells don't break off and go other places and just stay happily on the 8th cranial nerve and are just overgrowths of schwannoma cells? And did I just answer my own question?
Sharon ~
You've posed good questions and this post may be redundant art this late date but Webster's defines a 'cancer' as "a malignant tumor of potentially unlimited growth that expands locally by invasion and systemically by metastasis". The latter part of the definition is what separates an acoustic neuroma from a cancerous tumor. It is not malignant and does not metastasize. But you knew that. ;)
The size issue has been credibly answered by others. I will note, however, that, an MRI does have it's limitations. Nerves are very thin and the MRI cannot 'see' every inch of our skull from infinite angles (you don't move during the MRI scan) which is why, on occasion, some things are a 'surprise' to the surgeon when he actually sees the tumor (such as it being attached to one or more nerves). This is strictly anecdotal - the radiologist's report stated that my AN was 4.5 cm but my neurosurgeon said it was much closer to 5 cm when he got to it. Go figure! :)
Jim