What measurement of AN counts?

[ellieopp]

I am new to this board and very confused. I was first diagnosed in 2009 with  AN 6.6 x 6.1 mm. Six months later the size was unchanged. In Mar. 2012 I went to a different radiologist with my previous MRI Cd's and the written reports. This time the overall measurements including both intra and extra canalicular components was 1.8 cm transvers 0.3 AP and 0.5 cm CC along the rxtra canalicular components. The ENT doctor sent me to a neurosurgeon because it "tripled in size." The neurosurgeon suggested Gamma Knife surgery but when I said does he think it will continue to grow  at this rate at my age 75, he said it really didn't triple in size. If I want I can wait another 6 months and get another MRI.
This got me to thinking since the recent MRI mentioned nothing about the change in size over the 3 year period. When I called the radiologist's office I was told that somehow the doctor writing the report did not see my previous MRI's. I brought them back and the report was amended to indicate that the vestibular schwannoma is without interval change.
So this means that it did not grow in three years and I'm 75 years old and my only symptom is lessened hearing in my left ear for which I wear a hearing aid to help with word discrimination. All of you give the measurements of your AN's and now my question is what's the size of mine .6 cm or 1.8 cm? I am planning to watch and wait and will see the ENT doctor in a few months, have the audiologist check my hearing and get another MRI when the ENT doctors orders it.

[CHD63]

Hi ellieopp and welcome to this forum .....

I am not a doctor, but from my journey in the AN World it is my understanding that acoustic neuromas typically start growing on the vestibular portion of the auditory nerve that runs through the internal auditory canal (IAC) from the cochlea to the brain stem.  The canal is longer than it is wide, hence the growing tumor expands within this confined space (larger ANs grow out of the canal and toward the brain stem, often taking on a mushroom-shaped appearance).  The dimensions given by radiologists vary considerably.  It is my understanding that the length of the AN is the measurement they watch the most closely.

The important thing for you is the fact that it is apparently not growing perceptibly.  This is good news as it allows you to wait and watch.  If your symptoms are essentially unchanging and MRIs demonstrate no growth, that is a good thing.

If it would make you feel better, you can always send copies of all of your MRI CDs and your audiograms to House Ear Clinic (see:  http://www.houseearclinic.com/consultation/acousticneuroma ) for a free consultation with no obligation to go there for treatment.  Stanford University, UPMC (Pittsburgh, PA), and several other medical facilities around the country will do the same.  I would strongly urge you to do that for your own peace of mind.

Best thoughts.  Clarice

[ellieopp]

Thanks for your reply Clarice.
I guess that I'm a 1.8 cm AN when I compare my size on these boards.
It's just a matter of thinking and at my age I'm not rushing to do anything drastic. My hearing won't get better anyway.

[Mickey]

Hi Ellieopp! There is a big difference between .6cm and 1.8cm (3X). In any case what's the most important factor at your age (75) is if it has "stabilized" There  is a bigger chance they have with minimal symptoms and hopefully not presenting any danger. Keep up the monitoring and stay informed. Best wishes, Mickey

[mk]

ANs may be confined completely inside the internal auditory canal (IAC) or may have a portion inside the IAC and extend into the CPA (cerebellopontine angle). Think of an ice-cream cone shape for the latter.

The big differences in the size reported by various doctors/ radiologists depend on whether they count the linear portion that extends inside IAC (i.e. the cone), or if they consider just the spherical portion extending into the CPA (i.e. the ice cream).  Just to give you an idea:
A reading of say 2 cm (TR) x 1.8 cm (AP) x 1.9 cm (CC) (i.e. similar lengths in all dimensions), is most likely a representation of the spherical portion only.
A reading of 2.8 cm (TR) x 1.8 cm (AP) x 1.9 cm (CC) (i.e. the tranverse direction is much larger than the others), will typically contain the portion that extends into the IAC. In terms of volume (which is what really matters) there is not much difference, as the volume of the spherical portion is much larger.  But it can be quite significant in terms of scaring you out with statements that "it has doubled or tripled".
Note also that the transverse reading (i.e. dimension from side to side), is the most important, as it will determine whether there is compression on the brainstem etc. Your neurosurgeon is of course the most qualified person to judge this.

Marianna